JR( )OS

15-112

REPUBLIC OF INDONESIA

REPUBLIC OF INDONESIA

PREPARATORY SURVEYON

NORTH SUMATRAMINI HYDROPOWER PROJECT

(PPP INFRASTRUCTURE PROJECT)

FINAL REPORT

JANUARY 2016

JAPAN INTERNATIONAL COOPERATION AGENCY

NIPPON KOEI CO., LTD.

REPUBLIC OF INDONESIA

REPUBLIC OF INDONESIA

PREPARATORY SURVEYON

NORTH SUMATRAMINI HYDROPOWER PROJECT

(PPP INFRASTRUCTURE PROJECT)

FINAL REPORT

JANUARY 2016

JAPAN INTERNATIONAL COOPERATION AGENCY

NIPPON KOEI CO., LTD.

Source: SRTM DEM Data (http://srtm.csi.cgiar.org)

Figure I Location Map

Source: JICA Survey Team

Figure II Project Layout

Poring-1:Intake-1

Poring-1: Powerhouse-1

Poring-1: Waterway-1

Poring-2: Waterway-2

Poring-2: Powerhouse-2

Jakarta

Medan

Project Location

Table I Principle Features of Hydropower Formulation Key Item Poring-1 Small Hydropower Poring-2 Small Hydropower

Hyd

rolo

gica

l Fea

ture

s

River (River System)

Poring River (Sibundong River System)

Poring River (Sibundong River System)

Catchment Area 87.45 km2 91.02 km2 River Runoff Max. 14.79 35-day 9.97

95-day 8.09 185-day 6.61 275-day 5.67 355-day 4.58

Min. 4.35 Mean 7.10

Max. 15.40 35-day 10.3895-day 8.42 185-day 6.88 275-day 5.91 355-day 4.76

Min. 4.52 Mean 7.39

Address of the Project Desa Siantar Naipospos Kecamatan Adian Koting Kabupaten Tapanuli Utara Provinsi Sumatera Utara

Desa Siantar Naipospos Kecamatan Adian Koting Kabupaten Tapanuli Utara Provinsi Sumatera Utara

Ope

ratio

n F

eatu

res

Type of Hydropower Run-of-River Type Run-of-River Type Full Supply Level at Intake EL. 646.50 m EL. 441.60 m Tail Water Level EL. 441.50 m EL. 192.70 m Gross Head 205.40 m 249.30 m Effective Head Max. 197.50 m Max. 240.40 m Plant Discharge Max. 6.00 m3/s Max. 5.00 m3/s Installed Capacity 2 × 4,850 kW 2 ×4,850 kW Annual Power Generation 69.1 GWh/year 75.3 GWh/year

Fac

ilit

y O

utli

nes

Intake Weir Type Concrete Gravity Type Nil Height 7.00 m

Crest Length 44.50 m Power Intake Free Flow Conduit, 7.00~4.00 m

(W), 3.50 m (H), 16.40 m (L) Nil

Sand Trap Basin Open Type with Side Spillway, 2-Bay, 3.00 m (W), 4.00~7.50 m

(H), 34.4 m (L) Nil

Headrace Free Flow Conduit and Channel, 1.70 m (W), 2.00~2.15 m (H), 2,471

m (L)

Free Flow Conduit and Channel, 1.60 m (W), 1.90~2.15 m (H), 2,581

m (L) Head Tank Open Type with Side Spillway,

1.70~6.00 m (W), 3.00~5.00 m (H), 25.20 m (L)

Open Type with Side Spillway, 1.60~5.00 m (W), 3.00~5.00 m (H),

24.00 m (L) Penstock Exposed Type, 1-Lane, φ1.35~1.00

m, 431.63 m (L), Steel (SM400) Exposed Type, 1-Lane, φ1.25~0.90

m, 858.87 m (L), Steel (SM400) Pipe Spillway Exposed Type, 1-Lane, φ0.95 m,

431.06 m (L), Steel Pipe (SM400)Exposed Type, 1-Lane, φ1.25 m,

854.90 m (L), Steel Pipe (SM400)Tailrace Free Flow Conduit, 4.00~2.00 m

(W), 3.10~1.00 m (H), 33.10 m(L)Free Flow Channel, 3.00 m (W),

3.10~1.00 m (H), 9.00 m (L) Powerhouse Above-ground Type Above-ground Type Hydro Turbine Type Horizontal Francis, 2-unit Horizontal Francis, 2-unit Type of Generator 3-Phase Synchronous, 2-unit 3-Phase Synchronous, 2-unit

Riv

er U

tili

zati

on

Environmental Discharge 0.31 m3/sec Nil Flow Utilization Factor 69.8% 66.0% Capacity Factor 82.7% 89.8% Plant Factor 82.1% 89.6%

Source: JICA Study Team

Table II Facility Features of Hydropower Project Key Item Poring-1 Small Hydropower Poring-2 Small Hydropower

[MAJOR STRUCTURAL FEATURES] Intake Weir Type Concrete Gravity Type

Nil Dimensions 7.0 m (H), 33.00 m (W), Crest Length 44.50 m

(W) Sand Flush Steel Roller Gate, 1-No, 2.00m (W), 2.00m (H)

Power Intake

Type Free Flow RC Conduit Nil Dimensions 7.00~4.00 m (W), 3.50 m (H), 16.40 m (L)

Screen 2-No, 3.00 m (W), 2.00 m (H) Gate Steel Roller Gate, 2-No, 2.00m(W), 2.00m(H) Steel Roller Gate, 1-No, 2.00m(W), 2.00m(H)

Sand Trap Basin

Type Free Flow RC Channel

Nil

Dimensions 2-No, 2.00 m (W), 4.00~7.50 m (H), 31.90 m (L), Side Spillway Crest 18.00 m (W), Invert

Slope 1:10 Sand Flush Gate Steel Roller Gate, 2-No, 1.00 m(W), 1.00 m(H)Screen 2-No, 2.00 m (W), 3.50 m (H)

Headrace Type Free Flow RC Conduit and Channel Free Flow RC Conduit and Channel Dimensions 1.7 m (W), 2.00~2.15 m (H), 2,471 m (L),

Invert Slope 1/500 1.6 m (W), 1.90~2.15 m (H), 2,581 m (L),

Invert Slope 1/500 Head Tank Type Free Flow RC Channel Free Flow RC Channel

Dimensions 1.70~6.00 m(W), 3.00~5.00 m(H), 25.20 m(L) 1.60~5.00 m(W), 3.00~5.00 m(H), 24.00m(L)Screen 1-No, 6.00 m (W), 3.50 m (H) 1-No, 5.00 m (W), 3.50 m (H)

Penstock Type, Lane Exposed Type with Saddle Support, 1 Lane Exposed Type with Saddle Support, 1 LaneMaterial SM400 SM400 Inner Diameter 1.35 ~ 1.00 m 1.25 ~ 0.90 m Steel Thickness 6~18 mm 6~20 mm Length 431.63 m 858.87 m Anchor Block 7-No 11-No Support Type Saddle Support, 59-No, Max. Span 6.00 m Saddle Support, 122-No, Max. Span 6.00 m

Pipe Spillway

Type, Lane Exposed Type with Saddle Support, 1 Lane Exposed Type with Saddle Support, 1 LaneMaterial SM400 SM400 Inner Diameter 0.95 m 1.25 m Steel Thickness 6 mm 6 mm Length 431.06 m 854.90 m Anchor Block 7-No 9-No Support Type Saddle Support, 60-No, Max Span 6.00 m Saddle Support, 123-No, Max Span 6.00 m

Tailrace Channel

Type Free Flow Conduit Free Flow Channel Dimensions 4.00~2.00 m(W), 3.10~1.00 m(H), 33.10 m(L) 3.00 m (W), 3.10~1.00 m (H), 9.00 m (L)

Tailrace Outlet

Type Side Overflow Type Free Flow RC Channel Dimensions Crest Length 14.00 m (W) 3.00 m (W), 1.40 m (H)

Powerhouse

Type Above-ground, RC type Above-ground, RC type Dimensions 10.8 m (W), 38.0 m (L), 9.0 m (H) 10.8 m (W), 38.0 m (L), 9.0 m (H)

Turbine Type Horizontal Francis Type Horizontal Francis Type Output, No 5,000 kW, 2-No 5,000 kW, 2-No Rotation 750 rpm 750 rpm Specific Speed 73.8 mkW 58.7 mkW Inlet Valve Through Flow Butterfly Type Through Flow Butterfly Type

Generator Type 3-Phase Synchronous Type 3-Phase Synchronous Type Capacity, No 5,380 kVA, 2-No 5,380 kVA, 2-No Voltage 6,600 V 6,600 V Rotation 750 rpm 750 rpm Frequency 50 Hz 50 Hz

Transmission Line 3-Phase, 33 kV, 2-Circuits with 1 pole arrangement, 33.8 km (L)

3-Phase, 33 kV, 2-Circuits with 1 pole arrangement, 36.7 km (L)

Access Road 4.47 km (L) × 4.0 m (W) including 1.0 m (W) Shoulder

4.14 km (L) × 4.0 m (W) including 1.0 m (W) Shoulder

Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini i Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Executive Summary

1. Background and Necessity of the Project

(1) Government Policy on Power Sector in Indonesia

The government of Indonesia has been promoting new power development through the first Crash

Programme in year 2006, and the second Crash Programme in 2010 to cope with the rapid growth of

electricity demand in Indonesia. Both of the Crash Programme aimed to encourage private investment

into Indonesian power sector to increase power generation capacity. The second Crash Programme in

2010 is focused on acceleration of the renewable energy development especially for small hydropower to

harness Indonesian’s abundant hydropower potential. However, as it is difficult for PLN to arrange all of

the necessary power development investment, the government of Indonesia introduced Feed-in Tariff

(FIT) system to small scale renewable energy development to fill the investment gap for renewable

energy development by the private sector.

(2) Small Hydropower Development in Indonesia

Under these circumstances, the number of private companies interested to small hydro IPPs has been

increasing significantly, although actual physical construction has not been progressing smoothly.

According to RUPTL 2013-2022, the small hydropower potential in Indonesia was estimated to

7,500MW but only 86.1MW of the potential had been developed so far. The developed capacity is just

over 1% of its potential in the country. In May 2014, in order to accelerate the small hydropower

development, the government of Indonesia increased tariff for 40% and simplify the licensing procedure.

In July 2015, the tariff was again increased and the new tariff was linked to USD currency.

(3) Situation of Power Supply and Small Hydropower Development in North Sumatra

According to the latest RUPTL 2015-2024, installed capacity of North Sumatra is estimated to 2,487 MW,

however the effective installed capacity, which deducts halted generators due to breakdown or

overhauling, is estimated to 1,872 MW. While, the peak power demand of the region is recorded 1,450

MW and the reserve margin of power supply is calculated to 23% which is lower than the PLN’s target of

35%. The growth rate of power electricity demand for next 10 years is estimated to 13.1% and it

necessitates generation capacity expansion of over 500 MW per year. Alleviation of stringent tight power

supply demand balance by investment of power supply facilities are of the important issues in Indonesia.

According to the “Project for the Master Plan Study of Hydropower Development in Indonesia” which

was conducted by JICA in 2011, the un-developed hydropower potential was estimated to 435 MW and it

is expected the power development harnessing abundant hydropower potential in North Sumatra.

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Preparatory Survey on North Sumatra Mini ii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(4) Development of the Mini Hydropower Development in North Sumatra by the Indonesian Private

Company

The subject North Sumatra mini hydropower project has been planned to apply FIT, and the project’s

development permits has been by special purpose company (PT. JDG, hereinafter referred to as JDG).

The project is the two mini hydropower development using water flow of the Poring river that flow

through North Tapanuli regency in North Sumatra Province in Sumatra. JDG has conducted

pre-feasibility study in 2013 and Nippon Koei Co., Ltd. (hereinafter referred to as Nippon Koei) has

conducted review of the pre-feasibility study. The project viability was confirmed in the two studies,

and JDG has decided to promote the project under support of Nippon Koei.

2. Objectives of this Survey

JICA Survey Team conducted the survey to develop detailed plan of this Project for expected JICA’s

Private Sector Investment Fund (PSIF) application. The survey includes current status of power sector,

project scope, project cost, funding for the project, project schedule, construction method, project

implementation system, operation and maintenance system, natural and social environmental

consideration, financial analysis, project scheme and risk analysis.

3. Outlines of the Survey

3.1 Hydrology

(1) Collection of Hydrological Data and Hydrological Monitoring

The hydrological data is collected from the existing seven rainfall gauging stations and five water level

gauging stations near the Poring River basin. The Survey Team visited the rainfall gauging stations and

confirmed the observation method, and conducted verification of the collected data. The water level

monitoring of the Poring River and neighboring Pargaringan River has been conducted since December

2014, and July 2014, respectively. The rainfall monitoring has been conducted since December 2014 to

September 2015.

(2) Low Flow Analysis

The rainfall analysis is conducted and calculates the annual basin rainfall of the Poring site to 4,889

mm/year. The figure is considered adequate since neighboring rainfall monitoring station recorded annual

average of 4,714 mm/year. The continuous long-term duration daily stream flow at Poring-1 intake site is

estimated for 10 years duration. The ten years duration data is prepared by adopting stream flow

monitoring data of the Poring River, converting from neighboring station, and estimated by hydrological

model. As the result, the average discharge from January 2005 to September 2015 is estimated to 7.5

m3/s.

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Preparatory Survey on North Sumatra Mini iii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(3) Flood Analysis

For calculation of the flood peak discharge at project site, the probable rainfall is calculated from the

observed rainfall data at Hobuan rainfall gauging station, where is located close to the project site. The

flood peak discharge is calculated for 100 years return period, and the peak discharge of Poring-1 and

Poring-2 planned intake site are 680 m3/s and 710 m3/s, respectively.

3.2 Geology

Based on the geological surface investigation, 11 holes 150 m in total core drilling were carried out for

major structures. Geological and geotechnical conditions were evaluated from the results of standard

penetration test (SPT), penetration test, in-situ tests.

The basement of proposed structures in the project area, mainly consists of hard granite (the Sibolga

Granite Complex), locally of soft welded tuff (Toba Tuff). Accordingly, it was confirmed the stability

of structural foundation.

3.3 Layout Study

(1) Waterway Layout

1) The layout of Intake Weir and Headrace, the layout of Penstock and Powerhouse is determined by

optimization of construction cost and energy loss as well as geological condition, environment, etc.

2) The waterway alignment is designed to go through the terrain obtained in the topographic survey in

this Project. Available gross head for hydropower generation is 205.4 m for Poring-1 and 249.3 m

for Poring-2.

(2) Maximum Plant Discharge

1) Maximum plant discharge is selected comparing the benefit and cost from 10 alternative installed

capacities between 6 and 15 MW. The installed capacity 10 MW is the most optimum for both

Projects due to the highest IRR, and the maximum plant discharge is set at 6.0 m3/s for Poring-1 and

5.0 m3/s for Poring-2,

2) Based on the maximum plant discharge, the maximum effective head is 197.50 m for Poring-1 and

240.40 m for Poring-2 as well as the installed capacity is 10 MW.

3) Accordingly, the annual energy generation is simulated to be 69.1 GWh for Poring-1 and 75.3 GWh

for Poring-2.

3.4 Basic Design of Major Facilities

(1) Poring-1 Small Hydropower Project

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Preparatory Survey on North Sumatra Mini iv Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The major civil facilities are composed of; 1) Intake Weir, 2) Headrace, 3) Head Tank, 4) Penstock and Pipe

Spillway, 5) Powerhouse and 6) Tailrace.

(2) Poring-2 Small Hydropower Project

The major civil facilities are composed of; 1) Headrace, 2) Head Tank, 3) Penstock and Pipe Spillway, 4)

Powerhouse and 5) Tailrace.

As a result of geological investigation, it was revealed that the Intake Weir for Poring-2 is located on the thick

and weak talus deposit. Therefore, the Intake Weir was cancelled and designed to directly intake the power

discharge from Poring-1.

3.5 Basic Design of Electro-Mechanical Equipment and Transmission Line

Installed turbine capacity will be 2 units × 5,000 kW, installed generator capacity will be 2 units × 5,380

kVA and the capacity of main transformer will be 1 unit × 11,000 kVA for both hydropower plants.

Generated electricity shall be transmitted to the existing Tarutung Substation by 33 kV transmission line

with 35 km long four circuits with two pole arrangement along the existing road to Tarutung. The 33 kV

voltage of transmission line was selected due to the optimization study comparing the cost and transient

analysis of 20 kV, 33 kV and 150 kV. At the end of transmission line, the electricity shall step-down to

20 kV and hand over to PLN at the Tarutung Substation.

3.6 Construction Plan and Cost Estimates

Construction period for preparatory access road work is 6 months, and Main work is 36 months, by the

planning of method statement and quantities which is made from basic condition. Each commissioning

test at construction schedule was estimated for Poring-1 mini hydropower project at 27 months and

Poring-2 mini hydro project at 36 months including 4 month allowance. The critical path of the Project

will be on the construction of both Headraces.

3.7 Environmental Considerations

(1) Initial Environmental Examination (IEE)

After conducting the IEE in examining available data, hearing from stakeholders, carrying out site

reconnaissance, conducting site survey and laboratory analysis, it is concluded that impact resulting from

the Project will be not significant. The predicted impacts could be avoided or minimized in applying

countermeasures.

(2) Impact on Social Environment

Effort was made to avoid any resettlement due to constructing project facilities. Consequently, there will

be no resettlement from constructing the Project facilities. The compensation for about 40 ha of

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Preparatory Survey on North Sumatra Mini v Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

acquired land shall be disbursed appropriately based on the prepared land acquisition plan (LAP). It is

highly recommended to provide assistances to the affected community continuously in an operation

phase.

(3) Impact on Natural Environment

No particular impact on natural environment such as fish and fishery for the recession section between

Intake Weir and Poring-2 Powerhouse, since the environmental flow is designed to discharge 0.31 m3/s

uniformly from Intake Weir.

(4) Environmental Permissions

Developer have already obtained the Environmental monitoring/management permission (UKL-UPL) for

hydropower facility area and under the process of the UKL-UPL for Transmission Lines.

3.8 Law

The legal bases of this IPP project is Electricity Law (Law No.30/2009). In Indonesia, many IPP projects

has been done already and there are no major legal obstacle. The Feed in Tariff (FIT) regulation was

amended at the end of Jun, 2015 (MEMR Regulation No.19/2015) and the currency basis was shifted

from Indonesian Rupiah (IDR) to US Dollar (USD). The FIT in North Sumatra shall be 13.2 cents/kWh

from year 1 to year 8 and 8.25 cents/kWh from year 9 to year 20. Foreign investment in Indonesia is

regulated and limited by sector basis (Presidential Regulation No.39/2014, “Negative List”) and the

maximum investment ratio of foreign investor for this project is 49%.

Final Report

Preparatory Survey on North Sumatra Mini vi Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(Blank page)

Final Report

Preparatory Survey on North Sumatra Mini i Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

REPUBLIC OF INDONESIA

PREPARATORY SURVEY ON NORTH SUMATRA MINI HYDROPOWER PROJECT (PPP INFRASTRUCTURE PROJECT)

FINAL REPORT

TABLE OF CONTENTS

Figure I Location Map

Figure II Project Layout

Table I Principle Features of Hydropower Formulation

Table II Facility Features of Hydropower Project

Executive Summary

Page

CHAPTER 1 BACKGROUND AND PURPOSE OF THE SURVEY ........................................ 1-1

1.1 Background ............................................................................................................................. 1-1

1.2 Outline of the Project .............................................................................................................. 1-2

1.3 Purpose of the Survey .............................................................................................................. 1-4

1.4 Project Area ............................................................................................................................. 1-4

1.5 Indonesian Concerned Authority ............................................................................................. 1-4

CHAPTER 2 POWER SECTOR SURVEY .................................................................................. 2-1

2.1 Socioeconomic Status .............................................................................................................. 2-1

2.1.1 Socioeconomic Status of Indonesia ........................................................................... 2-1

2.1.2 Socioeconomic Status of North Sumatra ................................................................... 2-3

2.1.3 Economic Development Policy of Indonesia ............................................................. 2-6

2.2 Overview of the Policies and Institutions of the Indonesian Government .............................. 2-8

2.2.1 Policy and Institutions on Electric Power Development ........................................... 2-8

2.2.2 Electric Power Development System......................................................................... 2-9

2.2.3 Power Development Plan ........................................................................................... 2-9

2.2.4 Electricity Tariff ....................................................................................................... 2-12

2.2.5 Budget and Financial Sources .................................................................................. 2-14

2.2.6 Acceleration of Private Investment and Development ............................................ 2-15

2.3 Current Status of Development Policy for Promotion of Private Sector Participation on

Small Hydropower Business ................................................................................................. 2-18

2.3.1 Regulation of the Ministry of Energy and Mineral Resources ................................ 2-18

2.3.2 PPA and Power Tariff ............................................................................................... 2-20

2.3.3 Revision of PPA ....................................................................................................... 2-22

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Preparatory Survey on North Sumatra Mini ii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

2.3.4 Permission/License Required for Small Hydropower Business ............................... 2-22

2.3.5 Development Status of Small Hydropower ............................................................. 2-23

2.3.6 Issues on Small Hydropower Development ............................................................. 2-25

2.4 Status of Power Supply and Power Development Plan in North Sumatra ............................ 2-26

2.4.1 Current Status of Power Supply in North Sumatra .................................................. 2-26

2.4.2 Power Demand Projection of North Sumatra .......................................................... 2-31

2.4.3 Generation Expansion Plan in North Sumatra ......................................................... 2-32

2.4.4 Issue of Power Supply and Demand Balance in North Sumatra .............................. 2-34

2.5 Significance of The Project in North Sumatra ....................................................................... 2-34

2.5.1 Effect of The Project to Power Supply and Demand Balance in North Sumatra ..... 2-34

2.5.2 Significance of the Project to the Power System in North Sumtra .......................... 2-35

CHAPTER 3 SITE CONDITIONS ............................................................................................... 3-1

3.1 Site Conditions ........................................................................................................................ 3-1

3.2 Access to the Site .................................................................................................................... 3-2

3.3 Topography .............................................................................................................................. 3-3

3.3.1 Topography of the Site ............................................................................................... 3-3

3.3.2 Topographic Survey ................................................................................................... 3-4

3.4 Hydrology ................................................................................................................................ 3-7

3.4.1 Study Area ................................................................................................................. 3-7

3.4.2 Available Hydrological Data ...................................................................................... 3-9

3.4.3 Rainfall Data ............................................................................................................ 3-12

3.4.4 Runoff Data ............................................................................................................. 3-16

3.4.5 Low Flow Analysis .................................................................................................. 3-18

3.4.6 Flood Analysis ......................................................................................................... 3-27

3.5 Geology ................................................................................................................................. 3-41

3.5.1 Regional Geology .................................................................................................... 3-41

3.5.2 Geological Investigation .......................................................................................... 3-42

3.5.3 General Geology around the Proposed Structure ..................................................... 3-43

3.5.4 Site Geology and Evaluation ................................................................................... 3-45

3.5.5 Construction Materials ............................................................................................. 3-63

3.5.6 Seismic Risk Study .................................................................................................. 3-63

CHAPTER 4 OPTIMIZATION OF DEVELOPMENT PLAN .................................................. 4-1

4.1 Optimization of Development Plan ......................................................................................... 4-1

4.1.1 Limitations of Development Plan .............................................................................. 4-1

4.1.2 Optimization of Development Plan ........................................................................... 4-1

4.2 Installed Capacity .................................................................................................................... 4-2

4.3 Optimization of Layout ........................................................................................................... 4-3

4.3.1 Layout Study of Poring-1 Intake Weir and Headrace ................................................ 4-3

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Preparatory Survey on North Sumatra Mini iii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

4.3.2 Layout Study of Poring-2 Intake Weir and Headrace ................................................ 4-5

4.3.3 Layout Study of Poring-1 Penstock and Powerhouse ................................................ 4-7

4.3.4 Layout Study for Poring-2 Penstock and Powerhouse ............................................... 4-9

4.4 Head Loss and Effective Head .............................................................................................. 4-10

4.4.1 Effective Head ......................................................................................................... 4-10

4.4.2 Type and Efficiency of Turbine and Generator ........................................................ 4-11

4.5 Plant Discharge ...................................................................................................................... 4-13

4.6 Annual Energy ....................................................................................................................... 4-15

CHAPTER 5 BASIC DESIGN ....................................................................................................... 5-1

5.1 Basic Design of Civil Works ................................................................................................... 5-1

5.1.1 Poring-1 Intake Weir .................................................................................................. 5-1

5.1.2 Poring-1 Headrace Channel ....................................................................................... 5-7

5.1.3 Poring-1 Head Tank ................................................................................................. 5-10

5.1.4 Poring-1 Penstock .................................................................................................... 5-13

5.1.5 Poring-1 Head Tank Spillway .................................................................................. 5-16

5.1.6 Poring-1 Powerhouse ............................................................................................... 5-18

5.1.7 Poring-2 Power Intake ............................................................................................. 5-21

5.1.8 Poring-2 Headrace ................................................................................................... 5-22

5.1.9 Poring-2 Head Tank ................................................................................................. 5-25

5.1.10 Poring-2 Penstock .................................................................................................... 5-27

5.1.11 Poring-2 Head Tank Spillway .................................................................................. 5-31

5.1.12 Poring-2 Powerhouse ............................................................................................... 5-32

5.2 Basic Design of Hydro-Mechanical Works ........................................................................... 5-35

5.2.1 General ..................................................................................................................... 5-35

5.2.2 Sand Flush Gate and Hoist ....................................................................................... 5-35

5.2.3 Sand Flush Gate stoplog .......................................................................................... 5-36

5.2.4 Power Intake Trashrack ........................................................................................... 5-37

5.2.5 Power Intake Gate and Hoist ................................................................................... 5-37

5.2.6 Power Intake Stoplog ............................................................................................... 5-38

5.2.7 Sand Drain Gate and Hoist at Sand Trap ................................................................. 5-39

5.2.8 Sand Trap Trashrack ................................................................................................ 5-39

5.2.9 Sand Drain Gate and Hoist at Head Tank ................................................................ 5-40

5.2.10 Head Tank Trashrack ............................................................................................... 5-40

5.2.11 Penstock and Spillway Pipe ..................................................................................... 5-41

5.3 Basic Design of Electro-Mechanical Works .......................................................................... 5-43

5.3.1 Basic Design Conditions .......................................................................................... 5-43

5.3.2 Hydraulic Turbines .................................................................................................. 5-43

5.3.3 Generators ................................................................................................................ 5-47

5.3.4 Main Transformers ................................................................................................... 5-48

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Preparatory Survey on North Sumatra Mini iv Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.3.5 Basic Electrical Connection in Power Station ......................................................... 5-49

5.3.6 Powerhouse Crane ................................................................................................... 5-50

CHAPTER 6 CONSTRUCTION PLAN ....................................................................................... 6-1

6.1 Construction Plan .................................................................................................................... 6-1

6.1.1 Basic condition .......................................................................................................... 6-1

6.1.2 Construction Schedule ............................................................................................... 6-2

6.1.3 Preparatory Access Road Work .................................................................................. 6-5

6.1.4 Temporary Facility Plan ............................................................................................. 6-5

6.1.5 Spoil Bank ................................................................................................................. 6-6

6.1.6 Poring-1 Main Construction Works ........................................................................... 6-7

6.1.7 Poring-2 Main Construction Works ......................................................................... 6-13

CHAPTER 7 NATURAL AND SOCIAL ENVIRONMENTAL CONSIDERATION ............... 7-1

7.1 Project Components with Potential Impacts on the Environment ........................................... 7-1

7.2 Present Conditions in the Project Area .................................................................................... 7-2

7.2.1 Natural Environment ................................................................................................. 7-2

7.2.2 Social Environment ................................................................................................... 7-5

7.3 Legal and Institutional Framework ....................................................................................... 7-22

7.3.1 Legislation on Natural and Social Environmental Considerations .......................... 7-22

7.3.2 Institutional Framework ........................................................................................... 7-26

7.4 Alternatives ........................................................................................................................... 7-27

7.5 Scoping .................................................................................................................................. 7-28

7.6 Initial Environmental Examination (IEE) .............................................................................. 7-32

7.6.1 Terms of Reference (TOR) of the IEE ..................................................................... 7-32

7.6.2 Results of the IEE .................................................................................................... 7-34

7.7 Environmental Management ................................................................................................. 7-50

7.7.1 Institutional Arrangement ........................................................................................ 7-50

7.7.2 Mitigation Measures and Monitoring Plan .............................................................. 7-51

7.7.3 Implementation Schedule ........................................................................................ 7-57

7.8 Stakeholder Meeting .............................................................................................................. 7-59

7.9 Estimation of Reduction of Greenhouse Gas ........................................................................ 7-62

7.10 Conclusions and Recommendations ...................................................................................... 7-63

7.10.1 Conclusions.............................................................................................................. 7-63

7.10.2 Recommendations .................................................................................................... 7-63

Final Report

Preparatory Survey on North Sumatra Mini v Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

List of Tables

Page

Table 1.2.1 Features of the Project ............................................................................................... 1-3

Table 2.1.1 Population of Indonesia ............................................................................................. 2-2

Table 2.1.2 Principal Economy Index of Indonesia ...................................................................... 2-2

Table 2.1.3 Ratios of the Principal Industries of Indonesia to GDP ............................................. 2-3

Table 2.1.4 Trend of the Regional GDP of North Sumatra ........................................................... 2-3

Table 2.1.5 Percentage of Major Industries to the Regional GDP of North Sumatra ................... 2-4

Table 2.1.6 Population of Regencies in North Sumatra Province ................................................. 2-5

Table 2.1.7 Poverty Ratio of North Sumatra Province ................................................................. 2-5

Table 2.1.8 Indonesia Economic Policies ..................................................................................... 2-6

Table 2.2.1 Outline of Crash Program ....................................................................................... 2-11

Table 2.2.2 35 GW Power Development Plan (2015-2019) ....................................................... 2-11

Table 2.2.3 Share of Each Region under the 35 GW Power Development Plan (2015-2019) ... 2-11

Table 2.2.4 Share of Each Source under the 35 GW Power Development Plan (2015-2019) .... 2-12

Table 2.2.5 Electricity Tariff of PLN (1/2) ................................................................................. 2-13

Table 2.2.5 Electricity Tariff of PLN (2/2) ................................................................................. 2-14

Table 2.2.6 Subsidy from the Government to PLN .................................................................... 2-15

Table 2.2.7 Power Generation Cost by Sources ......................................................................... 2-15

Table 2.3.1 Power Purchase Price for Small Hydropower Project ............................................. 2-20

Table 2.3.2 Power Purchase Price for Small Hydropower Project Utilizing Existing

Structures ................................................................................................................. 2-20

Table 2.3.3 Power Purchase Price for Small Hydropower Project Under Operation or

Already Contracted PPA .......................................................................................... 2-21

Table 2.3.4 Permission/License for Small Hydropower Business .............................................. 2-22

Table 2.3.5 Renewable Energy Potentials .................................................................................. 2-23

Table 2.3.6 Development Plan of Renewable Energy ................................................................ 2-23

Table 2.3.7 Status of Small Hydropower Development (As of February 2015) ......................... 2-25

Table 2.4.1 Electric Energy Consumption by Type of Users in North Sumatra in 2014 ............ 2-29

Table 2.4.2 Power Stations Currently Operated in North Sumatra ............................................. 2-30

Table 2.4.3 Abbreviation of Generation Type Used by PLN ...................................................... 2-31

Table 2.4.4 Power Demand Projection in North Sumatra ........................................................... 2-31

Table 2.4.5 Necessary Expansion for Generation Capacity, Transmission, and Substations

between 2015 and 2024 ........................................................................................... 2-32

Table 2.4.6 Generation Expansion Plan of North Sumatra ......................................................... 2-33

Table 2.4.7 Necessary Investment of Generation Capacity from 2015 to 2024 ......................... 2-33

Table 3.3.1 Available Topographic Data ....................................................................................... 3-4

Table 3.3.2 Scope of New Topographical Survey and Mapping .................................................. 3-5

Table 3.3.3 National Benchmark for the Topographic Survey ..................................................... 3-6

Table 3.3.4 Coordinates of Project Benchmarks........................................................................... 3-6

Final Report

Preparatory Survey on North Sumatra Mini vi Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 3.4.1 Mean Monthly and Annual Rainfall around the Poring River Basin ......................... 3-8

Table 3.4.2 Mean Daily Evaporation around the Poring River Basin .......................................... 3-9

Table 3.4.3 Availability of Daily Rainfall and Daily Discharge / Water Level Data .................. 3-10

Table 3.4.4 Availability of Monthly Rainfall Data ..................................................................... 3-10

Table 3.4.5 Observation of Hydrological Data by the JICA Survey Team ................................. 3-12

Table 3.4.6 Equation of Regression Line and Correlation Coefficient ....................................... 3-14

Table 3.4.7 Estimated Basin Rainfall at Poring-1 Intake Site..................................................... 3-15

Table 3.4.8 Estimated Basin Rainfall at the Kolang Water Level Gauging Station .................... 3-16

Table 3.4.9 Summary of Discharge Data around the Poring River Basin .................................. 3-17

Table 3.4.10 Comparison of Hydrological and Geological Features ............................................ 3-20

Table 3.4.11 Runoff Coefficient Estimated by Observed Data in 2014-2015 .............................. 3-23

Table 3.4.12 Reference of the Poring-1 Intake Site Daily Flow ................................................... 3-26

Table 3.4.13 Monthly Average Discharge at the Poring-1 Intake Site .......................................... 3-27

Table 3.4.14 Annual Maximum Daily Rainfall at the Hobuan Gauging Station .......................... 3-29

Table 3.4.15 Probable Maximum Daily Point Rainfall at Hobuan ............................................... 3-30

Table 3.4.16 Probable Basin Mean Rainfall for the Poring River Basin ...................................... 3-31

Table 3.4.17 Runoff Coefficient Depending on the Catchment’s Feature .................................... 3-34

Table 3.4.18 Peak Flood Discharge at the Proposed Intake Sites by SCS Method ....................... 3-34

Table 3.4.19 Peak 100-year Discharge Estimated by Rational Formula ...................................... 3-35

Table 3.4.20 Comparison of Peak Flood Discharges .................................................................... 3-36

Table 3.4.21 Maximum Daily Rainfall during January-July at the Hobuan Gauging Station ...... 3-38

Table 3.4.22 Probable Maximum Daily Point Rainfall for the Dry Season in Hobuan ................ 3-39

Table 3.4.23 Peak Flood Discharge at the Proposed Intake Sites in the Dry Season .................... 3-40

Table 3.5.1 PGA and Probability of Earthquake in the Project Area .......................................... 3-64

Table 3.5.2 Design Peak Ground Acceleration for the Project ................................................... 3-65

Table 3.5.3 Classification of the Site for Ground Surface .......................................................... 3-65

Table 3.5.4 Design Earthquake Coefficient ................................................................................ 3-65

Table 4.4.1 Head Loss and Discharge......................................................................................... 4-11

Table 4.4.2 Design Water Level .................................................................................................. 4-11

Table 4.5.1 Plant Discharge and Installed Capacity of Poring-1 and Poring-2 ........................... 4-14

Table 4.6.1 Annual Energy for Poring-1 and Poring-2 ............................................................... 4-15

Table 5.1.1 Relationship of Slope of Stream Bed and Design Water Depth ................................. 5-3

Table 5.1.2 Non-uniform Flow Calculation Result of Headrace Channel-1 ................................. 5-9

Table 5.1.3 Target Water Levels for Poring-1 Head Tank .......................................................... 5-12

Table 5.1.4 Water Hammer Analysis and Penstock Steel Thickness for Poring-1 ...................... 5-15

Table 5.1.5 Non-Uniform Flow Analysis for Overflow Spillway Pipe for Poring-1 .................. 5-17

Table 5.1.6 Poring-1 Powerhouse Setting Level......................................................................... 5-19

Table 5.1.7 Non-uniform Flow Calculation Result of Headrace Channel-2 ............................... 5-23

Table 5.1.8 Target Water Levels in Poring-2 Head Tank ............................................................ 5-26

Table 5.1.9 Water Hammer Analysis and Poring-2 Penstock Steel Thickness ........................... 5-30

Final Report

Preparatory Survey on North Sumatra Mini vii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 5.1.10 Non-Uniform Flow Analysis for Overflow Spillway Pipe for Poring-2 .................. 5-31

Table 5.1.11 Poring-2 Powerhouse Setting Level......................................................................... 5-33

Table 5.2.1 Equipment List of Hydro-Mechanical Works .......................................................... 5-35

Table 5.2.2 Specification of Sand Flush Gate ............................................................................. 5-36

Table 5.2.3 Specification of Sand Flush Gate Stoplog ............................................................... 5-37

Table 5.2.4 Specification of Power Intake Trashrack ................................................................. 5-37

Table 5.2.5 Specification of Power Intake Gate ......................................................................... 5-38

Table 5.2.6 Specification of Power Intake Gate Stoplog ............................................................ 5-38

Table 5.2.7 Specification of Sand Drain Gate at Sand Trap Basin ............................................. 5-39

Table 5.2.8 Specification of Sand Trap Trashrack ...................................................................... 5-39

Table 5.2.9 Specification of Sand Drain Gate at Head Tank ...................................................... 5-40

Table 5.2.10 Specification of Head Tank Trashrack ..................................................................... 5-40

Table 5.2.11 Material Comparison between Steel and FRP ......................................................... 5-41

Table 5.2.12 Specification of Penstock ......................................................................................... 5-42

Table 5.2.13 Specification of Head Pond Spillway Pipe .............................................................. 5-42

Table 5.3.1 Operating Water Level Conditions .......................................................................... 5-43

Table 5.3.2 Turbine Output ......................................................................................................... 5-44

Table 5.3.3 Specific Speed (Ns) ................................................................................................. 5-45

Table 5.3.4 Turbine Setting Level .............................................................................................. 5-45

Table 5.3.5 Maximum Runaway Speed ...................................................................................... 5-45

Table 5.3.6 Comparison of Performance of Inlet Valves ............................................................ 5-46

Table 5.3.7 Types and Ratings of Drainage Pumps .................................................................... 5-46

Table 5.3.8 Power Output of Generator ...................................................................................... 5-47

Table 5.3.9 Fly Wheel of Turbine and Generator ....................................................................... 5-48

Table 5.3.10 Necessary Fly Wheel of Turbine and Generator ...................................................... 5-48

Table 5.3.11 Outline Specification for Powerhouse Crane ........................................................... 5-50

Table 6.1.1 Quantities of Access Road Work ............................................................................... 6-1

Table 6.1.2 Quantities of Main Work ........................................................................................... 6-1

Table 6.1.3 Quantities of Access Road Work ............................................................................... 6-5

Table 7.1.1 Project Component .................................................................................................... 7-1

Table 7.2.1 Maximum and Minimum Temperatures in North Sumatra ........................................ 7-2

Table 7.2.2 Population, Ethnicity, Language, and Religion .......................................................... 7-5

Table 7.2.3 Income ....................................................................................................................... 7-6

Table 7.2.4 Main Income Source .................................................................................................. 7-7

Table 7.2.5 Vulnerable Households in Total Affected Households .............................................. 7-8

Table 7.2.6 Rice Production ......................................................................................................... 7-9

Table 7.2.7 Rice Sufficiency ....................................................................................................... 7-10

Table 7.2.8 Rice Shortage Management (Ranking) .................................................................... 7-10

Table 7.2.9 Type of Trees and Area for Plantation (ha) .............................................................. 7-11

Table 7.2.10 Literacy Rate ............................................................................................................ 7-12

Final Report

Preparatory Survey on North Sumatra Mini viii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.11 School Enrolment .................................................................................................... 7-13

Table 7.2.12 Education Infrastructure .......................................................................................... 7-14

Table 7.2.13 Health Infrastructure (Distance to Village) .............................................................. 7-15

Table 7.2.14 Access from the Village to the Main Road .............................................................. 7-16

Table 7.2.15 Electrification Rate .................................................................................................. 7-17

Table 7.2.16 Source of Water........................................................................................................ 7-18

Table 7.2.17 Sources of Energy for Cooking................................................................................ 7-19

Table 7.2.18 Means of Transportation .......................................................................................... 7-20

Table 7.2.19 Places for Medical Treatment .................................................................................. 7-21

Table 7.2.20 Number of Cases and Deaths within 12 Months...................................................... 7-22

Table 7.3.1 Summary of Statutory Order in Indonesia ............................................................... 7-23

Table 7.3.2 Key Legislations Regarding Environmental Impact Assessment ............................ 7-23

Table 7.3.3 Contents of UKL-UPL ............................................................................................. 7-24

Table 7.3.4 State of Environmental Procedure and Further Requirements ................................. 7-25

Table 7.3.5 Governmental Administrative Bodies Relevant to the Project ................................ 7-26

Table 7.4.1 Alternatives .............................................................................................................. 7-27

Table 7.5.1 Anticipated Impact on Component 1 (Hydropower Plants) ..................................... 7-28

Table 7.5.2 Anticipated Impact on Component 2 (Transmission Lines) .................................... 7-30

Table 7.6.1 TOR of the IEE ........................................................................................................ 7-32

Table 7.6.2 IEE Results .............................................................................................................. 7-35

Table 7.6.3 Summary of the Survey Result ................................................................................ 7-41

Table 7.6.4 Location of Fish Species Survey ............................................................................. 7-42

Table 7.6.5 Result of Identified Fish Species ............................................................................. 7-42

Table 7.6.6 Type of Fish, Volume of Catch, and Economic Value .............................................. 7-44

Table 7.6.7 Location of the Water Sampling .............................................................................. 7-45

Table 7.6.8 Results of the Water Sampling ................................................................................. 7-45

Table 7.6.9 Summary of Affected Area, Households and Assets ................................................ 7-47

Table 7.6.10 Entitlement Matrix ................................................................................................... 7-49

Table 7.7.1 Roles and Responsibilities of Institutions Concerned in the Pre-construction /

Construction Phase .................................................................................................. 7-50

Table 7.7.2 Proposed Roles and Responsibilities for CSR Activity during the Operation

Phase ....................................................................................................................... 7-51

Table 7.7.3 Mitigation Measures and Monitoring Plan .............................................................. 7-51

Table 7.8.1 Summary of Focused Group Meeting ...................................................................... 7-59

Table 7.8.2 Summary of Public Consultation Meetings ............................................................. 7-60

List of Figures

Page

Figure 2.1.1 Economic Corridors Set in MP3EI ............................................................................ 2-7

Figure 2.2.1 BKPM One Stop Service Related to Power Generation Business ...................... 2-17

Final Report

Preparatory Survey on North Sumatra Mini ix Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Figure 2.3.1 Procedure for Small Hydropower Development ...................................................... 2-19

Figure 2.3.2 Planned Accumulated Renewable Energy Generation Capacity.............................. 2-24

Figure 2.4.1 Power Grid and Existing and Planned Power Stations ............................................ 2-27

Figure 2.4.2 Power Sector in North Sumatra Generation Unit..................................................... 2-28

Figure 3.1.1 River Profile of the Poring River ............................................................................... 3-1

Figure 3.2.1 Location Map of the Project ...................................................................................... 3-3

Figure 3.2.2 Conditions of the Existing Public Road ..................................................................... 3-3

Figure 3.3.1 Location Map of the Survey and Mapping Area ........................................................ 3-5

Figure 3.4.1 Watershed Area of Poring River ................................................................................ 3-7

Figure 3.4.2 Climate Patterns in Hutaraya near the Poring River Basin ........................................ 3-8

Figure 3.4.3 Mean Monthly Rainfall around the Poring River Basin ............................................ 3-9

Figure 3.4.4 Gauging Stations around the Poring River Basin .................................................... 3-11

Figure 3.4.5 Water Level Monitoring Stations at Kolang, Poring Bridge, and Pargaringan

Bridge ...................................................................................................................... 3-12

Figure 3.4.6 Double Mass Curve for Each of the Rainfall Gauging Station ................................ 3-13

Figure 3.4.7 Thiessen Polygon for Poring-1 Intake Site and Kolang Water Level Observatory .. 3-15

Figure 3.4.8 Monthly and Annual Basin Mean Rainfall of Poring-1 Intake Site ......................... 3-16

Figure 3.4.9 Monthly and Annual Basin Rainfall at the Kolang Water Level Gauging Station ... 3-16

Figure 3.4.10 Duration Curves of Collected Discharge Data ......................................................... 3-17

Figure 3.4.11 Daily Water Level at the Kolang Water Level Gauging Station .............................. 3-18

Figure 3.4.12 Outline of Low Flow Analysis ................................................................................. 3-19

Figure 3.4.13 Scatter Plot of Stream Flow Measured at Poring Bridge and Kolang

Observatories (June 2015 to July 2015) .................................................................. 3-21

Figure 3.4.14 Discharge Data Measured by BWS Sumatera II and Revised H-Q Curve .............. 3-22

Figure 3.4.15 H-Q Rating Curves at Discharge Measurement Points ............................................ 3-23

Figure 3.4.16 Daily Rainfall and Discharge at the Intake Sites ..................................................... 3-23

Figure 3.4.17 Tank Model Parameter for the Runoff at the Poring Bridge .................................... 3-25

Figure 3.4.18 Discharge Hydrograph of Simulated and Observed Discharge of the Poring River

at the Poring Bridge from 2014 to 2015 .................................................................. 3-25

Figure 3.4.19 Comparison of Flow Duration Curve of the Simulated and Observed Stream

Flow Discharge of the Poring River at the Poring Bridge ....................................... 3-26

Figure 3.4.20 Flow Duration Curve at the Poring-1 Intake Site from January 2005 to

September 2015 ....................................................................................................... 3-27

Figure 3.4.21 Area-Adjustment of Point Rainfall .......................................................................... 3-29

Figure 3.4.22 Annual Maximum Daily Rainfall with Different Distribution Types ...................... 3-30

Figure 3.4.23 Standard Dimensionless Hydrograph by SCS ......................................................... 3-31

Figure 3.4.24 Hydrograph for 20-year, 100-year, and 200-year Floods at the Intake Sites ........... 3-34

Figure 3.4.25 Topographical Measurement Points for Rational Formula Method ......................... 3-35

Figure 3.4.26 Comparison with 20-year Floods under Various Schemes in Sumatra .................... 3-37

Figure 3.4.27 Comparison with 100-year Floods under Various Schemes in Sumatra .................. 3-38

Final Report

Preparatory Survey on North Sumatra Mini x Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Figure 3.4.28 Comparison with 200-year Floods under Various Schemes in Sumatra .................. 3-38

Figure 3.4.29 Hourly Rainfall and Discharge in Poring in the Dry Season ................................... 3-39

Figure 3.4.30 Dry Season’s Flood Hydrographs for the Maximum Runoff Coefficients .............. 3-40

Figure 3.5.1 Geological Map of North Sumatera ......................................................................... 3-41

Figure 3.5.2 Location Map of Drilling Sites ................................................................................ 3-42

Figure 3.5.3 Geological Image of the Project Site ....................................................................... 3-45

Figure 3.5.4 Geological Map around Poring-1 Intake Weir ......................................................... 3-47

Figure 3.5.5 Geological Section along the Poring-1 Intake Weir Axis ........................................ 3-47

Figure 3.5.6 Geological Map around Poring-1 Head Tank .......................................................... 3-49

Figure 3.5.7 Poring-1 Head Tank Profile along the Penstock Alignment .................................... 3-49

Figure 3.5.8 Geological Map around Poring-1 Penstock ............................................................. 3-50

Figure 3.5.9 Geological Profile along Poring-1 Penstock ............................................................ 3-50

Figure 3.5.10 Geological Map around Poring-1 Powerhouse ........................................................ 3-52

Figure 3.5.11 Geological Profile along Poring-1 Powerhouse ....................................................... 3-52

Figure 3.5.12 Geological Condition around Poring-2 Intake ......................................................... 3-55

Figure 3.5.13 Geological Section along Poring-2 Intake Weir Axis .............................................. 3-55

Figure 3.5.14 Geological Map around Poring-2 Head Tank .......................................................... 3-58

Figure 3.5.15 Geological Profile along Poring-2 Head Tank ......................................................... 3-59

Figure 3.5.16 Geological Map around Poring-2 Penstock ............................................................. 3-60

Figure 3.5.17 Geological Profile along Poring-2 Penstock ............................................................ 3-61

Figure 3.5.18 Geological Map around Poring-2 Powerhous .......................................................... 3-62

Figure 3.5.19 Geological Profile along Poring-2 Powerhouse ....................................................... 3-62

Figure 3.5.20 Indonesia Earthquake Hazard Map .......................................................................... 3-63

Figure 3.5.21 Correlation between PGA and Annual Probability of Exceedance .......................... 3-64

Figure 4.1.1 Flowchart of Optimization of Dvelopment Plan ........................................................ 4-2

Figure 4.3.1 Alternative Location of Poring-1 Intake Weir ........................................................... 4-4

Figure 4.3.2 Alternative Layout of Poring-1 Intake Weir and Headrace ........................................ 4-4

Figure 4.3.3 Alternative Location of Poring-2 Intake Weir ........................................................... 4-6

Figure 4.3.4 Alternative Layout of Poring-2 Intake Weir and Headrace ........................................ 4-7

Figure 4.3.5 Alternative Location of Poring-1 Powerhouse .......................................................... 4-8

Figure 4.3.6 Alternative Layout of Poring-1 Penstock and Powerhouse ....................................... 4-8

Figure 4.3.7 Alternative Location of Poring-2 Powerhouse .......................................................... 4-9

Figure 4.3.8 Alternative Layout of Poring-2 Penstock and Powerhouse ..................................... 4-10

Figure 4.4.1 Turbine Selection Chart ........................................................................................... 4-12

Figure 4.4.2 Efficiency of Turbine and Generator ....................................................................... 4-13

Figure 4.5.1 Plant Discharge for Poring-1 ................................................................................... 4-15

Figure 4.5.2 Plant Discharge for Poring-2 ................................................................................... 4-15

Figure 4.6.1 Dependable Output and Energy for Poring-1 .......................................................... 4-16

Figure 4.6.2 Dependable Output and Energy for Poring-2 .......................................................... 4-16

Figure 5.1.1 H-Q Curve at Poring-1 Intake Weir Site .................................................................... 5-2

Final Report

Preparatory Survey on North Sumatra Mini xi Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Figure 5.1.2 Location of Poring-1 Intake Weir Axis ...................................................................... 5-2

Figure 5.1.3 Location of Poring-1 Intake Weir Site ....................................................................... 5-2

Figure 5.1.4 Flood Discharge Rating Curve at Intake Weir ........................................................... 5-3

Figure 5.1.5 Location of Counter Dam .......................................................................................... 5-4

Figure 5.1.6 Front View of Main Dam ........................................................................................... 5-5

Figure 5.1.7 Plan of Intake -1 ......................................................................................................... 5-5

Figure 5.1.8 Profile of Intake -1 Portal .......................................................................................... 5-5

Figure 5.1.9 Profile of Poring-1 Power Intake and Sand Trap Basin ............................................. 5-6

Figure 5.1.10 Suspended Sediments of Poring River ....................................................................... 5-7

Figure 5.1.11 Typical Section of Poring-1 Headrace ....................................................................... 5-8

Figure 5.1.12 Locations of River Crossings for Poring-1 .............................................................. 5-10

Figure 5.1.13 Typical Section of River Crossings .......................................................................... 5-10

Figure 5.1.14 Longitudinal Profile of Poring-1 Head Tank ........................................................... 5-12

Figure 5.1.15 Plan and Profile of Poring-1 Penstock ..................................................................... 5-13

Figure 5.1.16 Optimum Closing Time of Turbine and Generator .................................................. 5-14

Figure 5.1.17 Comparison of Pipe Spillway .................................................................................. 5-16

Figure 5.1.18 Type Selection Chart of Energy Dissipater .............................................................. 5-17

Figure 5.1.19 An Example of Impact Type Energy Dissipater ...................................................... 5-17

Figure 5.1.20 Typical Dimensions of Impact Type Energy Dissipater ........................................... 5-18

Figure 5.1.21 H-Q Curve at Powerhouse-1 Site ............................................................................. 5-19

Figure 5.1.22 Plan of Poring-1 Powerhouse .................................................................................. 5-20

Figure 5.1.23 Profile of Poring-1 Powerhouse ............................................................................... 5-20

Figure 5.1.24 Longitudinal Profile between Poring-1 Tailrace and Poring-2 Power Intake .......... 5-21

Figure 5.1.25 Typical Section of Poring-2 Headrace ..................................................................... 5-22

Figure 5.1.26 Layout of Headrace Channel Crossing the Village .................................................. 5-23

Figure 5.1.27 Typical Section of Village Crossing ......................................................................... 5-24

Figure 5.1.28 Locations of River Crossings ................................................................................... 5-24

Figure 5.1.29 Typical Section of River Crossings .......................................................................... 5-25

Figure 5.1.30 Longitudinal Profile of Poring-2 Head Tank ........................................................... 5-26

Figure 5.1.31 Plan and Profile of Poring-2 Penstock ..................................................................... 5-28

Figure 5.1.32 Optimum Closure Time of Turbine and Generator .................................................. 5-29

Figure 5.1.33 H-Q Curve at Powerhouse-2 Site ............................................................................. 5-32

Figure 5.1.34 Plan of Poring-2 Powerhouse .................................................................................. 5-33

Figure 5.1.35 Profile of Poring-2 Powerhouse ............................................................................... 5-34

Figure 5.3.1 Selection Chart for Turbine Type ............................................................................. 5-44

Figure 6.1.1 Preparatory Access Road Work .................................................................................. 6-3

Figure 6.1.2 Main Work Schedule .................................................................................................. 6-4

Figure 6.1.3 Concrete Pouring Schedule ........................................................................................ 6-5

Figure 6.1.4 Schedule for Number of Generator on Site ................................................................ 6-6

Figure 6.1.5 Layout of Project Road and Temporary Access Road ............................................... 6-8

Final Report

Preparatory Survey on North Sumatra Mini xii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Figure 6.1.6 Figure 3.4.19 Flow Duration Curve at Poring-1 Intake Site ...................................... 6-9

Figure 6.1.7 Layout of Project Road and Temporary Access Road ............................................... 6-9

Figure 6.1.8 Typical Section of Diversion Work 1st Stage .......................................................... 6-10

Figure 6.1.9 Typical Section of Diversion Work 2nd Stage ......................................................... 6-10

Figure 6.1.10 Drainage Capacity of Diversion Work 2nd Stage .................................................... 6-11

Figure 7.2.1 Maximum and Minimum Temperatures in North Sumatra ........................................ 7-2

Figure 7.2.2 National Park in Sumatra Island ................................................................................ 7-3

Figure 7.2.3 Land Usage ................................................................................................................ 7-4

Figure 7.2.4 Public Water Supply Space ...................................................................................... 7-18

Figure 7.4.1 Original Layout and Alternative Layout for Headrace Channel .............................. 7-27

Figure 7.7.1 Implementation Schedule ........................................................................................ 7-58

Final Report

Preparatory Survey on North Sumatra Mini xiii Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Abbreviations

(1) Organization

JICA Japan International Cooperation Agency

IIF Indonesia Infrastructure Finance

PLN PT. PLN (Persero)

PU Department of Public Works

Samuel PT. Samuel International

JDG PT. Jaya Dinamika Hydroenergi

NK Nippon Koei Co., Ltd.

NEF New Energy Foundation

(2) Measurement

mm millimeter

cm centimeter

m meter

km kilometer

km2 square kilometer

m3 cubic meter

m3/s cubic meter per second

kV kilovolt

kW kilowatt

MW megawatt

kWh kilowatt hour

GWh gigawatt hour

kVA kilovolt ampere

kg kilogram

ton metric ton

sec, s second

min minute

hr hour

yr year

IDR Indonesian Rupiah

US$ US Dollar

US¢ US Cent

¥ Japanese Yen

(3) Elevation

EL. Elevation above sea level

WL Water Level

FSL Full Supply Water Level

FWL Flood Water Level

TWL Tail Water Level

RWL Rated Water Level

(4) Economy and Finance

IRR Internal Rate of Return

EIRR Economic Internal Rate of Return

FIRR Financial Internal Rate of Return

ROE Return of Equity

FC Foreign Currency

LC Local Currency

LS Lump Sum

(5) Others

Pre-FS Pre Feasibility Study

FS Feasibility Study

BD Basic Design

DD Detailed Design

CS Construction Supervision

IPP Independent Power Producer

BOT Build, Operate and Transfer

CW Civil Works

MW Metal Works

E&M Electrical and Mechanical Works

SS Sub-station

TL Transmission Line

(6) Exchange Rate as at October 2015

US$ 1.00 = IDR 13,300

¥ 1.00 = IDR

Final Report

Preparatory Survey on North Sumatra Mini xiv Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

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Final Report

Preparatory Survey on North Sumatra Mini 1-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 1 BACKGROUND AND PURPOSE OF THE SURVEY

1.1 BACKGROUND

(1) Current Situation and Issues on the Power Sector in Indonesia

According to the PT. PLN (Persero) Electricity Supply and Business Plan from 2015 to 2024 (RUPTL

2015-2024), the peak load demand of Indonesia is 33,157 MW, while the generation capacity of the

country is 43,457 MW. The reserve margin of the power supply is 31%, which is lower than the target of

35% according to PLN policy. The electric demand of the country from 2009 to 2013 has kept increasing

with an annual growth rate of 7.8% and the electric demand is deemed to continue with high annual

growth rate of approximately 8%. This tight power supply and demand balance in the country becomes an

imminent issue in Indonesia’s power sector. Especially, as the Sumatra power system expected the rapid

increase of peak power demand, the peak power demand of 5,017 MW in 2014 is expected to be 13,141

MW by 2024. The existing generating capacity of the Sumatra power supply is 6,116 MW; therefore,

power development is urgently needed in the Sumatra Region.

(2) Government Policy on Power Sector in Indonesia

In order to cope with the rapid growth of electric demand, the Government of Indonesia has been

promoting new power development through the first Crash Program in 2006, and the second Crash

Program in 2010. Both of these Crash Programs aimed to encourage private investment into Indonesia’s

power sector to increase power generation capacity. The second Crash Program in 2010 is focused on

acceleration of renewable energy development especially for small hydropower to harness Indonesia’s

abundant hydropower potential. However, as it is difficult for PLN to arrange all of the necessary power

development investment, the Government of Indonesia introduced the Feed-in Tariff (FIT) system for

small-scale renewable energy development to fill the investment gap of renewable energy development

by the private sector.

(3) Small Hydropower Development in Indonesia

Under these circumstances, private companies tend to be interested in small hydro development and the

number of such companies has been increasing significantly, although actual physical construction has

not been progressing smoothly. According to RUPTL 2013-2022, the small hydropower potential in

Indonesia was estimated at 7,500 MW but only 86.1 MW of the potential had been developed so far. The

developed capacity is just over 1% of its potential in the country. In May 2014, in order to accelerate

small hydropower development, the Government of Indonesia increased its tariff by 40% and simplify the

licensing procedure. In July 2015, the tariff was again increased and the new tariff was linked to

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Preparatory Survey on North Sumatra Mini 1-2 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

US$ currency.

(4) Situation of Power Supply and Small Hydropower Development in North Sumatra

According to the latest RUPTL 2015-2024, the installed capacity of North Sumatra is estimated to be

2,487 MW; however, the effective installed capacity, which deducts halted generators due to breakdown

or overhauling, is estimated at 1,872 MW. Meanwhile, the peak power demand of the region is recorded

at 1,450 MW and the reserve margin of power supply is calculated to be 29% which is lower than the

PLN’s target of 35%. The growth rate of power electricity demand for the next ten years is estimated at

13.1% and it necessitates generation capacity expansion of over 500 MW per year. According to the

“Project for the Master Plan Study of Hydropower Development in Indonesia” (JICA 2011), the

undeveloped hydropower potential was estimated at 435 MW and an increase in power development is

expected by harnessing the abundant hydropower potential in North Sumatra.

(5) Mini Hydropower Development in North Sumatra by Indonesian Private Company

The North Sumatra Mini Hydropower Project has been planned to apply FIT, and the project’s

development permits have been secured by the special purpose company (PT. Jaya Dinamika

Hydroenergi hereinafter referred to as JDG). The project is the development of two mini hydropower

stations using water flow of the Poring River that originates in the mountain range of North Tapanuli

Regency in North Sumatra Province, Sumatra, and flows to the Indian Ocean. JDG has conducted a

pre-feasibility study in 2013 and Nippon Koei Co., Ltd. (hereinafter referred to as Nippon Koei) has

conducted a review of the pre-feasibility study. Project viability was confirmed in these two studies, and

JDG has decided to promote the project under the support of Nippon Koei.

1.2 OUTLINE OF THE PROJECT

(1) Purpose of the Project

The purpose of the project is to supply electricity to North Sumatra through the development of mini

hydropower plants, which are supposed to have less environmental impact compared with large- to

medium-scale hydropower plants. The project aims at contributing to the regional and national economic

development as well as improving the living standard of the people in and around the project area.

(2) Project Site/Names of Places

The project consists of the two project sites below. These are located in the western part of Tapanuli Utara

Regency (Kabupaten) of North Sumatra Province. The project area is about 10 to 20 km away westward

from Tartung, the capital town of Tapanuli Utara Regency.

・Poring-1 Mini Hydropower Station

・Poring-2 Mini Hydropower Station

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(3) Outline of the Project

The project will construct two mini hydropower stations (Poring-1 and Poring-2) on the Poring River.

These power stations will take water from the Poring River and generate 19,400 kW of electricity, in

total.

Table 1.2.1 Features of the Project

Poring-1

Mini Hydropower PlantPoring-2

Mini Hydropower Plant

Basin Area (km2) 88.1 91.5

Annual Precipitation (mm) 4,889 4,889 Annual Average River Discharge (m3/s)

7.53 -

Maximum Plant Discharge (m3/s)

6.0 5.0

Effective Head (m) 197.5 240.4

Installed Capacity (kW) 9,700 kW

（4,850 kW x 2 units）9,700 kW

（4,850 kW x 2 units） Annual Electrical Energy (GWh)

69.1 75.3

Source: Nippon Koei Co., Ltd.

(4) Implementation of the Project

i. Project Implementation, Operation and Maintenance (both Public and Private)

Upon completion of this study, and after confirmation of the financial and environmental viability,

Nippon Koei will plan to participate in the equity portion of the special purpose company (SPC).

The SPC is already established for each of the mini hydropower projects, namely, Poring-1 and

Poring-2 mini hydropower projects. The construction, operation and maintenance of the project

will be managed by the SPC, and the SPC will obtain necessary permits and licenses from PLN,

and the central/local government.

ii. Operation and Management Plan

The project will yield profit by selling electricity under the FIT price system, and the revenue of

selling electricity will cover the cost of the project such as construction cost, and operation and

maintenance cost.

(5) Project Implementation Schedule

Calendar Year 2014 2015 2016 2017 2018 ・・・ 2040

Schedule

Application for Licenses and Loan

D/D, Bid

Construction 2 years

Operation 20 years

F/S Survey

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(6) Project Effect

i. Expected Quantitative Effect

Expected quantitative effects of the two mini hydropower projects are as follows:

Poring-1 Mini Hydropower Project : Annual Energy 69.1 GWh (equivalent to 47,400

households electricity demand）

Poring-2 Mini Hydropower Project : Annual Energy 75.3 GWh (equivalent to 51,600

households electricity demand）

ii. Expected Qualitative Effect

Poring-1 and Poring-2 will improve the tight electricity demand and supply balance and

contribute to economic growth. Additionally, the project fits the national policy since it will

expedite the usage of renewable energy.

1.3 PURPOSE OF THE SURVEY

The JICA Survey Team (hereinafter referred to as the JICA Survey Team) will conduct a survey to

develop a detailed plan of the North Sumatra Mini Hydropower Project expected for JICA’s Private

Sector Investment Fund (PSIF) application. The survey includes the current status of the power sector,

project scope, project cost, funding for the project, project schedule, construction method, project

implementation system, operation and maintenance system, natural and social environmental

consideration, financial analysis, project scheme, and risk analysis.

1.4 PROJECT AREA

In and around North Tapanuli Regency in North Sumatra Province, Indonesia.

1.5 INDONESIAN CONCERNED AUTHORITY

The JICA Survey Team conducted the preparatory survey on North Sumatra Mini Hydropower Project in

the Republic of Indonesia under the cooperation of local partner companies, namely, PT. Samuel

International (Samuel) and JDG.

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CHAPTER 2 POWER SECTOR SURVEY

2.1 SOCIOECONOMIC STATUS

2.1.1 SOCIOECONOMIC STATUS OF INDONESIA

(1) Indonesia Economy Outlook

Indonesia retains its rank as the largest economy among the member countries of the Association of

Southeast Asian Nations (ASEAN), and the 16th largest worldwide in terms of gross domestic product

(GDP). The country has maintained a strong GDP growth rate of 6.0% from 2006 to 2012 except during

the global financial crisis in 2009, but the stable economic development has made significant strides in

reducing the incidence of poverty1. Although the economic growth rates after 2011 tend to slow down,

the country’s presence as the economic giant in the ASEAN region will stay unchanged.

In order to seek Indonesia’s further economic development, the Government of Indonesia announced the

Masterplan for Acceleration and Expansion of Indonesia's Economic Development (abbreviated as

MP3EI) in May 2011. By utilizing MP3EI, Indonesia aims to earn its place as one of the world’s

developed countries by 2025 with six times nominal GDP of its figure in 2010. President Joko Widodo

was inaugurated in 2014 and promulgated the policies, stated as election promises, which include

strengthening infrastructure investment in the rural areas, maritime infrastructure, and expediting private

investment. The new National Medium-term Development Plan (Rencana Pembangunan Jangka

Menengah Nasional: RPJMN 2015-2019) involves these election promises targeting to strengthen the

national identity as a maritime nation, as well as food security, energy security, and rural development.

(2) Population

The population of Indonesia has steadily increased to 253 million in 2014. The growth rate of the

population was kept around 1.4% until the early 2000s, but this number tends to go down in the recent

five years; it was recorded at 1.17% in 2014. Indonesia’s labor population with age range from 15 to 64

was 66.2% in 2014; this figure is higher than the figure of Japan (61%2). The chronological changes of the

Indonesian population are shown in Table 2.1.1.

1 “Asian Development Bank and Indonesia, Fact Sheet”, Asian Development Bank, 2014 2 Statistics published by the Statistics Bureau of the Ministry of Internal Affairs and Communications in Japan

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Table 2.1.1 Population of Indonesia

Source: World Bank

(3) Economy Index

The Indonesia economy index for the recent ten years is shown in Table 2.1.2. As shown in the table, the

average GDP growth rate in the past ten years is 5.72% and the figure varies around 6% except during the

global financial crisis in 2009. This stable growth contributes in the improvement of the poverty ratio3

from 16% in 2005 to 11.30% in 2014, and the unemployment ratio to the labor population is improved

from 11.20% in 2005 to 6.3% in 2013. These facts indicate that the stable economic growth contributes in

the improvement of poverty reduction and unemployment rate.

Table 2.1.2 Principal Economy Index of Indonesia

Source: World Bank

(4) Industry

The major industries in Indonesia are the manufacturing (motorbike), forest and fishery (e.g., palm oil/

rubber tree plantation), commercial/hotel/restaurant, and mining. The ratios of these industries to the

3 According to the Statistics Agency of Indonesia, poverty line is defined as the food and non-food poverty line. The food poverty line refers to the daily minimum requirement of 2,100 kcal per capita per day. The non-food poverty line refers to the minimum requirement for household necessities such as clothing, education, health, and other basic individual needs.

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Population 106 persons 224 228 231 234 237 241 244 247 250 253 239

Population Growth % 1.43 1.43 1.42 1.41 1.38 1.33 1.29 1.25 1.21 1.17 1.33

Population ages

between 15 ‐ 64% 65.13 65.10 65.06 65.04 65.06 65.16 65.34 65.60 65.89 66.22 65.36

Life Expectancy at

BirthYears 68.85 69.15 69.42 69.69 69.93 70.17 70.39 70.61 70.82 ‐ 69.89

YearAverageItem Unit

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Gross Domestic

Productmillion USD* 285,869 364,571 432,217 510,229 539,580 755,094 892,969 917,870 910,479 888,538 649,741

GDP Growth % 5.69 5.50 6.35 6.01 4.63 6.22 6.17 6.03 5.58 5.02 5.72

Consumer Price

Index (2010 = 100)68.68 77.69 82.67 90.75 95.12 100.00 105.36 109.86 116.91 124.39 97.14

Inflation, GDP

deflator% 14.33 14.09 11.26 18.15 8.27 15.26 7.47 3.75 4.71 5.39 10.27

Exchange Rate IDR per USD 9,705 9,159 9,141 9,699 10,390 9,090 8,770 9,387 10,461 11,865 9,766.79

Poverty Ratio % 16.00 17.80 16.60 15.40 14.20 13.30 12.50 12.00 11.40 11.30 14.05

Unemployment

Ratio% 11.20 10.30 9.10 8.40 7.90 7.10 6.60 6.10 6.30 ‐ 8.11

Foreign direct

investment, net

inflows

million USD 8,336 4,914 6,928 9,318 4,877 15,292 20,565 21,201 23,344 ‐ 12,753

*Dollar figures for GDP are converted from domestic currencies using single year official exchange rates. 

Item UnitYear

Average

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nation’s GDP from 2010 to 2013 are shown in Table 2.1.3.

Table 2.1.3 Ratios of the Principal Industries of Indonesia to GDP

Source: “Statistical Yearbook of Indonesia, 2014” Statistics Agency of Indonesia

2.1.2 SOCIOECONOMIC STATUS OF NORTH SUMATRA

North Sumatra Province, whose capital is Medan, is where the subject mini hydropower project is located.

The province has a land area of 71,681 km2, which is equivalent to 3.8% of the country, and has a

population of 13.33 million in 2013, which is 5.3% of Indonesia’s population. The economic growth rate

of North Sumatra is around 6% which is the same as the national figure. The major industries of the

province are agriculture (palm oil and rubber), manufacturing (food processing), trading, and

hotel/restaurant. The regional GDP of North Sumatra is Rp351,090 billion (equivalent to US$37.4

billion); this figure is 5.2% of the national GDP.

(1) Economy

The regional GDP of North Sumatra is the fifth largest among the 33 provinces in Indonesia, and the

figure is one-third of the value of the largest province which is the Special Capital Region of Jakarta. The

trend of the regional GDP of North Sumatra, which is published by the Statistics Agency of Indonesia is

shown in Table 2.1.4.

Table 2.1.4 Trend of the Regional GDP of North Sumatra

Source: 1) “Statistical Yearbook of Indonesia 2014” and “Statistical Yearbook of Indonesia 2013”, Badan Pusat Satistik (BPS) Indonesia, 2) World Bank, 3) “Sumatera Utara in Figures, 2014” and “Sumatera Utara in Figures, 2013”, BPS Statistics of Sumatera Utara Province

2010 2011 2012 2013

Agriculture, Livestock, Forestry, and Fishery 15.3% 14.7% 14.5% 14.4%

Mining and Quarrying 11.2% 11.8% 11.8% 11.2%

Manufacturing Industry 24.8% 24.3% 24.0% 1.7%

Electricity, Gas, and Water Supply 0.8% 0.8% 0.8% 0.8%

Construction 10.3% 10.2% 10.3% 10.0%

Trade, Hotel, and Restaurant 13.7% 13.8% 14.0% 14.3%

Transport and Communication 6.6% 6.6% 6.7% 7.0%

Financial, Real Estate, and Business Services 7.2% 7.2% 7.3% 7.5%

Services 10.2% 10.6% 10.8% 11.0%

YearIndustry

Province Unit 2009 2010 2011 2012 2013

Gross Regional Domestic Product 1) billion IDR 236,354 275,057 314,372 351,090 403,933

Exchange Rate (IDR to USD)  2) IDR/USD 10,390 9,090 8,770 9,387 10,461

Gross Regional Domestic Product million USD 22,748 30,258 35,845 37,403 38,612

Economic Growth Rate3) % 5.1% 6.4% 6.63% 6.22% 6.01%

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(2) Industry

The major industries of the province are agriculture (palm oil and rubber), manufacturing (food

processing), trading, and hotel/restaurant. The ratio of these industries to the regional GDP of North

Sumatra is around 20%. The percentage of these industries in the regional GDP is shown in Table 2.1.5.

Table 2.1.5 Percentage of Major Industries to the Regional GDP of North Sumatra

Source: “Statistik Daerah Provinsi Sumatera Utara 2014”, BPS Statistics of Sumatera Utara Province

In North Sumatra, agriculture and manufacturing are the principal industries. Major agriculture crops in

North Sumatra are rubber tree, palm, coconuts, cacao, and coffee. For manufacturing, food processing,

rubber, plastic factory, and timber processing are the major activities.

(3) Population

According to the Statistics Agency of Indonesia, the population of North Sumatra in 2013 was estimated

in the census conducted in 2010, with a population growth rate of 1.22%. The estimated populations of

the regencies in North Sumatra Province are shown in Table 2.1.6.

Industry 2011 2012 2013

1. Agriculture 22.5% 21.9% 21.3%

2. Mining and Quarrying 1.4% 1.3% 1.3%

3. Manufacturing 22.5% 22.1% 21.6%

4. Electricity , Gas & Water Supply 0.9% 0.9% 0.8%

5. Construction 6.4% 6.7% 6.9%

6. Trade, Hotel & Restaurant 19.2% 19.1% 19.3%

7. Transportation & Communication 9.2% 9.4% 9.5%

8. Financial Intermediaries, Insurance,Real Estate

& Ownerships of Dwelling Business Service7.0% 7.5% 7.7%

9. Social Community & Personal Service 10.9% 11.1% 11.5%

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Table 2.1.6 Population of Regencies in North Sumatra Province

Source: “Statistik Daerah Provinsi Sumatera Utara 2014”, BPS Statistics of Sumatera Utara Province

The population of North Tapanuli Regency, where the project is located, is estimated at 286,000 persons.

(4) Poverty Ratio

The poverty ratio of North Sumatra Province is shown in Table 2.1.7. As shown in the table, the poverty

ratio of the province decreased from 15.66% in 2006 to 10.06% in 2013. The poverty ratio of the province

is slightly lower than that of the national average as shown in Table 2.1.2.

Table 2.1.7 Poverty Ratio of North Sumatra Province

Source: “Statistik Daerah Provinsi Sumatera Utara 2014”, BPS Statistics of Sumatera Utara Province

According to statistics, the poverty ratio of North Tapanuli Regency in 2013 was 11.68% and the figure is

higher than that of the provincial average.

Total Area Number of Population Population Density

(km2) (person) (km

2)

01. Nias 98,032 133,388 136

02. Mandailing Natal 662,070 413,475 62

03. Tapanuli Selatan 4,353 268,824 62

04. Tapanuli Tengah 2,158 324,006 150

05. Tapanuli Utara 3,765 286,118 76

06. Toba Samosir 2,352 175,069 74

07. Labuhanbatu 2,561 430,718 168

08. Asaha n 3,676 681,794 185

09. Simalungun 4,369 833,251 191

10. Dairi 1,928 276,238 143

11. Karo 2,127 363,755 171

12. DeliSerdang 248,614 1,886,388 759

13. Langkat 6,263 978,734 156

14. Nias Selatan 1,626 295,968 182

15. Humbang Hasundutan 229,720 176,429 77

16. Pakpak Bharat 1,218 42,144 35

17. Samosir 243,350 121,924 50

18. Serdang Bedagai 1,913 605,583 317

19. Batu Bara 90,496 382,960 423

20. Padang Lawas Utara 3,918 232,746 59

21. Padang Lawas 389,274 237,259 61

22. Labuhanbatu Selatan 311,600 289,655 93

23. Labuhanbatu Utara 3,546 337,404 95

24. Nias Utara 1,502 129,053 86

25. Nias Barat Kota/City 54,409 82,854 152

71. Sib olg a 1,077 85,981 7983

72. Tanjungbalai 6,152 158,599 2578

73. Pematangsiantar 7,997 237,434 2969

74. Tebing Tinggi 3,844 149,065 3878

75. M ed an 26,510 2,123,210 8009

76. Bin j a i 9,024 252,263 2795

77. Padangsidimpuan 11,465 204,615 1785

78. Gunungsitoli 46,936 129,403 276

Sumatera Utara 71,681 13,326,307 186

Regency /City

Year 2005 2006 2007 2008 2009 2010 2011 2012 2013

% 14.68 15.66 13.9 12.55 11.51 11.31 11.33 10.67 10.06

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2.1.3 ECONOMIC DEVELOPMENT POLICY OF INDONESIA

Indonesia’s economic policy is composed of the nation’s long-term plan entitled the National Long-term

Development Plan (Rencana Pembangunan Jangka Panjang Nasional: RPJPN 2005-2025) and

short-term implementation plan entitled the National Medium-term Development Plan (Rencana

Pembangunan Jangka Menengah Nasional: RPJMN). RPJPN 2005–2025 serves as the basis for

development programs for 20 years commencing from 2005 to 2025. In addition, RPJPN 2005-2025 also

serves as a guideline for the preparation of the National Medium-term Development Plan (RPJMN),

which is the development program for the next five years. The government formulates and enacts the

annual government action plan (Rencana Kerja Pemerintah: RKP). These economic policies formulated

by the central government are further segmented to sectoral midterm strategic plan (Renstra KL) and

implementation plan (Renja KL). The structure of the economic development plan of the country is

shown in Table 2.1.8.

Table 2.1.8 Indonesia Economic Policies

National Level Development Plan Regional (Province, Regency, City) Level

Development Plan Sectoral

Development Plan General

Development PlanSectoral

Development PlanGeneral

Development PlanLong-term Plan

(20 years) National Long-term

Development Plan (RPJP Nasional)

Regional Long-term development plan

(RPJP Daerah) Mid-term Plan

(5 years) Central Government

Strategic Plan (Renstra KL)

National Medium-term

Development Plan (RPJM Nasional)

Regional Sectoral Strategic Plan

(Renstra SKPD)

Reginoal Medium-term

Development Plan (RPJM Daerah)

Implementation Plan (1 year)

Central Government Implementation Plan (Renja KL)

National Implementation

Plan (RKP)

Regional Sectoral Implementation

Plan (Renja SKPD)

Regional gov. Implementation

plan (RKP Daerah)Source: “Outline of World Land Policy”, Ministry of Land, Infrastructure, Transportation and Tourism

(1) National Medium-term Development Plan (RPJMN)

The Government of Indonesia formulated the National Long-term Development Plan (RPJPN 2005-2025)

with the vision and mission of (i) development and self-sustainability, (ii) justice and democracy, and (iii)

peace and unity. Under these visions and missions, the main objectives of the RPJPN 2005-2025 are set

to strengthen the competitiveness of agriculture and industry by reinforcing production efficiency,

targeting annual household income of US$60,000 by 2025, and improving food self-sufficiency. The

National Medium-term Development Plan (RPJMN) was formulated every five years following the

context of the RPJPN 2005-2025. The current medium-term plan is in the third phase of the planning

horizon (2015-2019), and was enacted in January 2015. RPJPN 2005-2025 assigned the following four

standards as national development norms, and set the priority development policy, which includes human

development, development of prioritized industry, rectifying regional disparities, and fair development:

a. Improvement of quality of life for society and individual;

b. Improved efforts for welfare, prosperity, and productivity should not create widened inequality;

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c. Special attention is given to lower and middle income people to improve their productivity without blocking, inhibiting, shrinking, and reducing their flexibility as major actors and continue to be agents of growth; and

d. Development activities must not impair or reduce the carrying capacity of the environment and the balance of the ecosystem.

RPJMN prioritizes infrastructure development in the sectors of energy and electricity, road, railway,

airport, marine port, water supply, and sewage. The necessary investment for these infrastructure

developments in five years is estimated to be US$45.80 billion, 50% of which (US$23 billion) needs to

be funded from non-governmental institutes such as the private sector.

(2) Master Plan for Acceleration and Expansion of Indonesia's Economic Development (MP3EI)

In May 2011, the Government of Indonesia announced the MP3EI as the center of the long-term plan

from 2010 to 2025. The plan aims to sextuplicate the current nominal GDP and for the country to be

ranked 10th in terms of GDP scale around the world by 2025. MP3EI adopts the basic vision of

development by creating a self-sufficient, advanced, just, and prosperous Indonesia; and the infrastructure

is focused on energy/electricity development, road construction, and railway construction, among others.

MP3EI sets six economic corridors, and assigns development targets for each corridor that aim to harness

the competitive advantages that are uniquely inherent in each of the six chosen corridors.

Source: KP3EI

Figure 2.1.1 Economic Corridors Set in MP3EI

The North Sumatra Mini Hydropower Project is located in North Sumatra Province and belongs to the

proposed Sumatra Economic Corridor in MP3EI. The development target of the corridor is to be a center

for production and processing of natural resources and as the nation’s energy reserve.

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2.2 OVERVIEW OF THE POLICIES AND INSTITUTIONS OF THE INDONESIAN GOVERNMENT

2.2.1 POLICY AND INSTITUTIONS ON ELECTRIC POWER DEVELOPMENT

Indonesia's energy policy is established based on the National Energy Policy (Kebijakan Energi Nasional:

KEN) and the National Energy Total Plan (Rencana Umum Energi Nasional: RUEN). Under these

policies, the National Electric Power General Plan (Rencana Umum Ketenagalistrikan Nasional: RUKN)

and Electric Power Implementation Plan (Rencana Umum Penyediaan Tenaga Listrik: RUPTL) are

prepared as implementation plans of these energy policies. The National Energy Policy (KEN) was

revised in January 2014 and the target values for each electric power energy resource were set as follows:

- Oil: less than 25% by 2015 and less than 20% by 2050.

- Natural gas: more than 22% by 2025 and more than 24% by 2050.

- Coal: less than 30% by 2025 and less than 25% by 2050.

- Renewable energy: more than 23% by 2025 and more than 31% by 2050.

In addition, the electrification rate was targeted at 85% by 2015 and nearly 100% by 2020. Domestic

primary energy was planned to be utilized for domestic purposes as much as possible. As for a related

policy, the National Energy Management Blueprint (Blueprint Pengelolaan Energi Nasional: BP-PEN)

2006-2025 was established and national targets related to energy were set. Based on the policy stated in

KEN, the Ministry of Energy and Mineral Resources (MEMR) established the National Electric Power

General Plan (RUKN) for electric power sector, then PLN which is the Indonesian government-owned

corporation prepares the Electric Power Implementation Plan (RUPTL), and PLN is principal entity to

implement it. The RUPTL envisions ten years horizon; however, it is revised annually.

The laws on energy and power sector in Indonesia include: 1) Energy Law (2007), 2) Electric Power Law

(2009), 3) Decree on Save Energy (2009), and 4) Geothermal Power Law (2003). The Energy Law of

2007 prescribes the management and usage of all energy resources such as 1) management of energy

resources by the government, 2) achievement of stable energy supply, 3) acceleration of resources

development, 4) formulation of national energy policy and energy plan, and 5) promotion of renewable

energy use. The new power law (2009) is a revision of the old energy law enacted in 1985. The Power

Law stated that the government is responsible for power supply. However, the law enables public

enterprises, private enterprises, cooperatives, and civic groups to participate in the power generation

business aiming to improve power supply ability. RUKN and the revision of power tariff require

parliament approval. The decree on energy-saving regulates that energy saving is imposed on large

energy consumers. The geothermal law allows private investors to participate development of geothermal

projects including steam development and supply, and power generation through geothermal development.

The processes of getting permits and licenses in each phase of geothermal energy development have

become clear by the law.

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Preparatory Survey on North Sumatra Mini 2-9 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

2.2.2 ELECTRIC POWER DEVELOPMENT SYSTEM

As the administrative organization for the electricity sector, the formulation of the overall policy for the

development and use of energy is done by the National Energy Board ((Dewan Energi Nasional: DEN).

The Ministry of National Planning and Development (Badan Perencanaan Pembangunan Nasional:

BAPPENAS) manages the national project development policy and coordination. The MEMR is the

administrative organization for the entire energy sector including the power sector. The PLN and

state-owned enterprises are under the control of the Ministry of State-Owned Enterprise (MSOE), while

the Ministry of Finance (MOF) manages the budget.

The MEMR is the supervisory institution for the energy sector and performs management and regulation

of state-owned energy companies in addition to policy planning. The Directorate of Electricity in MEMR

acts as the electric power administrator of the electricity sector and plays the role of regulation and

supervision, including coordination of the formulation of policy, procedures, and standards. It is

responsible for the formulation of the National Electric Power General Plan (RUKN).

In 2010, MEMR has organized the Directorate of New and Renewable Energy and Save Energy

(DGNREEC) for the development of renewable energy. The geothermal section of the Directorate of

Minerals, Coal and Geothermal, and renewable section of the Directorate of Electricity were integrated

into the DGNREEC. In the power generation business in Indonesia, PT. PLN and its subsidiary

companies and independent power producers (IPPs) are carrying out power generation. For transmission

and distribution of electricity, PLN has monopoly.

The Java-Bali system has larger scale power generation and supply. Power generation is being undertaken

by PLN, its subsidiary companies such as Indonesia Power (IP), Pumbankit Jawa Bali (PJB), and IPPs.

Transmission and distribution of the Java-Bali system are managed by the Power Transmission and

Distribution Center (P3B Jawa Bali) and five distribution offices. In Sumatra, two generation units

supervise regional power generation. As for the transmission and distribution, the Sumatra Power

Transmission and Distribution Center (P3B Sumatra) and seven regional offices are doing these tasks. In

other areas, the regional branch offices are carrying out integrated operation of power generation,

transmission, and distribution.

Sumatra generation unit consists of the North Sumatra generation unit (abbreviated as Sumbagut or

KITSBU) and South Sumatra generation unit (abbreviated as Sumbagsel or KITSBS). These generation

units were established in 2004 as part of the reorganization of PLN generation and distribution unit.

Sumbagut’s service area covers Ache, North Sumatra, and Riau provinces, while that of Sumbagsel

covers West Sumatra, Jambi, Bengkulu, South Sumatra, and Lampung provinces. In 2014, net installed

capacity of Sumbagut was 1,463 MW and that of Sumbagsel was 2,127 MW.

2.2.3 POWER DEVELOPMENT PLAN

Based on the national energy policy, the MEMR established RUKN and consequently, the RUPTL is

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Preparatory Survey on North Sumatra Mini 2-10 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

prepared, and power development is carried out by PLN. The RUKN describes major development

policies as shown below.

(1) Power supply planning policy

• Support MP3EI (2011-2025 in the Indonesian accelerated and enlarged economic development master plan);

• Avoidance of lack of power supply;

• Sufficient energy reserves;

• Development of peak load power plants by gas, pumped storage power plant; and

• Competitive electricity tariff structure.

(2) Diversification of power source

• Enhancement in the use of new and renewable energy;

• Establishment of sustainable power supply system for various energy power sources; and

• Support of gas supply for gas power generation and storage of coal for coal-fired power generation as a reduction measure for oil-dependency of fuel.

The RUPTL is a ten-year plan, but due to actual delays of the plan and changes in conditions, it is

updated every year. It is a power development plan prepared based on the present situation. The power

development plan is established to satisfy the electricity demand which is forecasted with considering

future economic and population growths. Construction of the transmission and distribution networks is

planned in order to harmonize with the power development plan. Further, the required construction costs

for these electric power development and fuel costs required for operation are estimated.

(3) Crash Program

In order to overcome the power shortage, the Government of Indonesia formulated the power plant

expansion plan (first Crash Program) in July 2006, focusing on coal-fired steam power plant

development. In January 2010, the second Crash Program was formulated replacing the first Crash

Program. The second Crash Program is more focused on power source diversification and introducing

renewable energy rather than coal-fired power plant development. The projects listed in the first and

second Crash Programs are called as fast-track program (FTP) I and FTP II, respectively, and those

projects were regarded as high priority projects in the country. The outline of the first and second Crash

Programs is shown in Table 2.2.1.

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Table 2.2.1 Outline of Crash Program Item First Crash Program Second Crash Program

Development Plan Period (Initial)

2006-2009 2010-2014

Developer PLN: 100% PLN: 37.4%, IPP: 62.6% Developed Capacity 10,000 MW

10,000 MW Review in 2012 and 2013, with 18,000 MW as the target.

Purpose Emergency power development in Java-Bali system mainly - Reduction in dependence on oil

Emergency power supply development - Power source diversification - Utilization of renewable energy

Power Supply Configuration

Coal: 100% Renewable energy: 54% (Geothermal: 41%, Hydro: 13%) Fossil fuel: 46% (Coal: 36%, Gas: 1%, Combined Cycle: 9%)

Progress in 2014 Completed: 7,368 MW In progress: 2,439 MW

Completed: 55 MW In progress: 17,403 MW

Legal Basis Presidential Decree No.71/2006 Presidential Decree No.04/2010 Source: PLN

Both of these Crash Programs are experiencing significant delays, main reasons for which are delays in

land acquisition and numerous licensing/permission procedures. Projects in the first Crash Program were

mainly contracted with Chinese companies. However, many problems such as lack of cash for

construction have been reported. Moreover, there were many defective and insufficient rated output of

power generation equipment, even if they were completed.

Furthermore, the new 2014 president, Mr. Jokowi, announced his ambitious plan to develop a 35 GW

power plant over the next five years. The shares of each region and power source under the 35 GW

Power Development Plan are shown in Table 2.2.3 and Table 2.2.4, respectively.

Table 2.2.2 35 GW Power Development Plan (2015-2019)

No. Status of Process Owner Total

Capacity PLN IPP

1 Construction 4.2 3.2 7.4

2 Committed 2.9 4.3 7.2

3 Procurement 2.2 11.3 13.6

4 Plan 5.1 9.6 14.7

Total (incl. Construction) 14.4 28.5 42.9

(excl. Construction) 10.2 25.2 35.5 Source: PLN

Table 2.2.3 Share of Each Region under the 35 GW Power Development Plan (2015-2019) (Unit: GW)

Sumatra Jawa-Bali

Kaliman tan

Sulawesi MalukuNusa

Tenggara Papua Total

PLN 1.1 5 0.9 2 0.3 0.7 0.2 10.2

IPP 7.6 15.9 1 0.7 0 0 0.1 25.3

Total 8.7 20.9 1.9 2.7 0.3 0.7 0.3 35.5Source: PLN

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Table 2.2.4 Share of Each Source under the 35 GW Power Development Plan (2015-2019) (Unit: GW)

Steam

Steam (Mine

Mouth)

Gas/ Combined

Hydro Geo-

thermal Others Total

PLN 5.6 - 7.2 1.4 0.1 0.1 14.4

Extension 5.2 - - - - - 5.2

IPP 12.3 1.6 6.2 0.2 1.1 0.7 22.1

Captive - 1.2 - - - - 1.2

Total 23.1 2.8 13.4 1.6 1.2 0.8 42.9*)Source: PLN

2.2.4 ELECTRICITY TARIFF

Indonesia's electricity tariff has been kept low by government subsidies. However, in order to mitigate the

financial burden of the government, an increase in electricity tariff and reduction of subsidies were

approved by the parliament in 2013. The increase in electricity tariff is done gradually. The power cost

deficit, which cannot be covered by PLN’s income from electricity sales, is made up by government

subsidies. Government subsidies are calculated by the Ministry of Finance. By these subsidies, electricity

tariff has been kept to a low and stable level without the effect of fuel costs. Government subsidies were

Rp3-4 trillion in the early 2000s. After then, due to the rise in oil prices, the power generation fuel price

has also increased. Finally, government subsidies were increased to Rp101 trillion in 2013. In 2013,

although the average generation cost was Rp1,207/kWh, the average sold electric price is Rp818.4/kWh.

Electrical tariff was increased by about 15% in October 2013. In addition, electricity tariffs for industrial

use (large-demand customer) were changed from 01 May 2013. Tariff for the customer with contract

capacity of more than 200 kVA increased by 38.9% but this was implemented at 8.6% every two

months. For contract of more than 30,000 kVA, tariff increase is 64.7%, but was implemented at 13.3%

every two months. In November 2014, another price increase was conducted.

The revised tariffs are as follows:

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Preparatory Survey on North Sumatra Mini 2-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.2.5 Electricity Tariff of PLN (1/2)

Source : PLN

Basic Tariff

(Rp./kVA/month) Condition before2013 Oct.2013 Nov.2014

Social

S‐1/TR 220 VA (per month) 14800 14800 14800

Block I : 0 ‐ 30 kWh 123 123 123

Block II : 30 ‐ 60 kWh 265 265 265

Block III : > 60 kWh 360 360 360

Block I : 0 ‐ 20 kWh 200 200 200

Block II : 20 ‐ 60 kWh 295 295 295

Block III : > 60 kWh 360 360 360

S‐2/TR 1,300 VA 605 708 708

S‐2/TR 2,200 VA 650 760 760

S‐2/TR 3,500 VA‐200 kVA 755 900 900

Peak K x P x 605 K x P x 735 K x P x 735

Off peak P x 605 P x 735 P x 735

kVArh ‐ 925 925

Residential

Block I : 0 ‐ 30 kWh 169 169 169

Block II : 30 ‐ 60 kWh 360 360 360

Block III : > 60 kWh 495 495 495

Block I : 0 ‐ 20 kWh 275 275 275

Block II : 20 ‐ 60 kWh 445 445 445

Block III : > 60 kWh 495 495 495

R‐1/TR 1,300 VA 790 979 1352

R‐1/TR 2,200 VA 795 1004 1352

R‐2/TR 3,500 VA‐5,500 VA 890 1145 1352

Block I H1 x 890

Block II H2 x 1,380

Business

Block I : 0 ‐ 30 kWh 254 254 254

Block II : > 30 kWh 420 420 420

Block I : 0 ‐ 108 kWh 420 420 420

Block II : > 108 kWh 465 465 465

B‐1/TR 1,300 VA 790 966 966

B‐1/TR 2,200 VA‐5,500 VA 905 1100 1100

Block I H1 x 900

Block II H2 x 1,380 1352 1352

Peak K x 800 K x P x 1,020 K x P x 1,020

Off peak 800 P x 1,020 P x 1,020

kVArh ‐ 1117 1117

13521352

900 VA 26500

23500450 VA

B‐3/TM more than 200 kVA

Customer/

CategoryContract Voltage

Usage Tariff(Rp./kWh)

450 VA 10000

900 VA

B‐1/TR

B‐1/TR

B‐2/TR 6,600 VA‐200 kVA

R‐1/TR

R‐3/TR more than 6,600 VA

900 VA 20000

S‐3/TM more than 200 kVA

R‐1/TR 11000less than 450 VA

S‐2/TR

S‐2/TR 15000

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Preparatory Survey on North Sumatra Mini 2-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.2.5 Electricity Tariff of PLN (2/2)

Notes, 1) K : Factor for cost between peak and off-peak in each system (region) decided by PLN (1.4 < K < 2.0)

2) P : Factor for social building, (Pure social building : 1.0, General social building : 1.3 ) 3) kVArh : If monthly average power factor is less than 85%, electric tariff for kVarh is added. 4) H1 : National average % saving on Lighting Time x Connected Power (kVA) 5) H2 : Energy consumption - H1 6) Q : Factor depending on commercial use and non-commercial use decided by PLN (08 < Q < 2.0)

Source: PLN

2.2.5 BUDGET AND FINANCIAL SOURCES

Budget for electric power business basically depends on PLN as the national executing agency and IPP

as the private investor. Income of PLN is composed of electricity sales and government subsidy, and

expenditure is composed of the purchase cost of electricity from IPP, fuel costs, maintenance costs, labor

costs, and depreciation cost. The electricity tariffs are decided by MEMR and should obtain the approval

Condition before 2013 Oct.2013 Nov.2014

Industry

Block I : 0 ‐ 30 kWh 160 160 160

Block II : > 30 kWh 395 395 395

Block I : 0 ‐ 72 kWh 315 315 315

Block II : > 72 kWh 405 405 405

I‐1/TR 1,300 VA 790 930 930

I‐1/TR 2,200 VA 905 960 960

I‐1/TR 3,500 VA‐14 kVA 915 1112 1112

Peak K x 800 K x P x 972 K x P x 972

Off peak 800 P x 972 P x 972

kVArh ‐ 1057 1057

Peak K x 680 K x P x 803 K x P x 1,115

Off peak 680 P x 803 P x 1,115

kVArh ‐ 864 1200

Peak & Off Peak 605 723 1191

kVArh ‐ 723 1191

Government Office & Public Use

P‐1/TR 450 VA 20000 575 575 575

P‐1/TR 900 VA 24600 600 600 600

P‐1/TR 1,300 VA 880 1049 1049

P‐1/TR 2,200 VA‐5,500 VA 885 1076 1076

H1 x 885

H2 x 1,380 1352 1352

Peak K x P x 750 K x P x 947 K x P x 1,115

Off peak P x 750 P x 947 P x 1,115

kVArh ‐ 1026 1200

P‐3/TR 997 1352

Railway

Peak K x 390 K x 483 K x 483

Off peak 390 483 483

kVArh ‐ 808 808

Bulk Use for Large Custome r

Peak & Off Peak K x 445 Q x 707 Q x 707

kVArh 445 Q x 707 Q x 707

Emergency/Multipurpos e

L/TR, TM, TT 1450 1650 1650

Contract　VoltageCustomer/

Category

UsageTariff(Rp./kWh)

26000450 VAI‐1/TR

31500

Basic Tariff

(Rp./kVA/month)

6,600 VA‐200  kVAP‐1/TR

P‐2/TM more than 200 kVA

900 VAI‐1/TR

14 kVA‐200  kVAI‐2/TR

I‐4/TT more than 30 MVA

more than 200 kVAI‐3/TM

23,000 (30,950

after 2013)

T/TM more than 200 kV

more than 200 kVC/TM 30000 ( 0 after

2013)

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Preparatory Survey on North Sumatra Mini 2-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

of the parliament.

IPP investors invest in the construction and operating costs and its return to investment is through the

selling price to PLN. To cope with the rapid growth of electricity demand, the construction costs of the

power plants, transmission lines, and distribution grids are covered by official funds as bilateral/

multilateral aid funds or official development assistance (ODA) funds through the Indonesian

government, funds of the Government of Indonesia, and PLN’s own funds. However, because of the lack

of official funds, use of private funds like IPP development such as export credit prepared by the

contractor/supplier and finance from banks has increased.

Government subsidies are compensating the deficit amount not covered by the income from the PLN

electricity fee. Subsidy amount is calculated based on the decree of the Ministry of Finance. If the

electricity sales price is lower than the generation cost in each category, PLN can receive the difference

in the amount as subsidy. The stable electric tariffs are being realized by this system without relation to

the fluctuation of fuel cost. However, progressively revising the electrical tariff to mitigate the financial

burden is aimed at reducing subsidies. Subsidy amount from 2008 to 2013 is shown in Table 2.2.6 below.

Table 2.2.6 Subsidy from the Government to PLN Year 2008 2009 2010 2011 2012 2013

Subsidy (Rp10^12) 78.6 53.7 58.1 93.2 103.3 101.2 Source：PLN Statistics 2013

As reference, generation costs of each power source are shown in Table 2.2.7.

Table 2.2.7 Power Generation Cost by Sources

Source：PLN Statistics 2013

2.2.6 ACCELERATION OF PRIVATE INVESTMENT AND DEVELOPMENT

As described above, in order to cope with the rapid growth in electricity demand, construction of power

plants is necessary; however, there is a limitation of official funds to cover the said costs. Investment

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Preparatory Survey on North Sumatra Mini 2-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

and development in the power sector through private funds are being enhanced. In 2013, about 24%

of electric power was supplied through IPPs. In the second Crash Program, which is currently in

progress, out of the 79 projects in total, with a capacity of 17,918 MW, 59 projects with 12,169 MW

capacity are IPP projects. Also, of the 35 GW power scheduled for completion by 2019, about 25.3 GW

are from IPP projects.

In order to enhance the development of small hydropower plants with less than 10 MW by private

investors, the Indonesian government provided the FIT system and set the electricity price somewhat

higher. Due to the requested large amount of equity and fund for small hydropower plant, IPPs and

numerous private investors showed interest and submitted IPP proposals to PLN. On the other hand, for

medium and large power projects of more than 10 MW, MEMR indicated the standard purchase prices

from IPP in the ministry decree for enhancement of private investment. In addition, due to complaints

received from the investors on the complicated and needed steps to get permits and licenses, the

Government of Indonesia opened and launched a one-window process system named as Pelayanan

Terpadu Satu Pintu (PTSP) PUSAT in the Investment Coordinating Board (Badan Koordinasi

Penanaman Modal: BKPM) in January 2015. Its purpose is to mitigate and speed up the process of

investment. As shown in Figure 2.2.1, application and acquisition of various permissions and licenses

such as Izin Lokasi (permission of land acquisition) by local government, electricity business license (Izin

Usaha Penyedia Tenaga Listrik: IUPTL) by MEMR, and power purchase agreement (PPA) by PLN are to

be done at BKPM.

The Government of Indonesia has put in place several incentive policy programs in order to promote

renewable energy development, which include the following:

• Income Tax：Developers can obtain 5% reduction in the income tax rate of its investment each year for a period of six years.

• Accelerated Depreciation：Depreciation of fixed assets can be completed within ten years; hence, reduce the income tax.

• Incentives for Foreign Companies：Income tax on dividends of foreign investors can be 10%.

• Import Duty：The import duty is exempted for equipment and machinery that cannot be procured in Indonesia.

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Preparatory Survey on North Sumatra Mini 2-17 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: BKPM

Figure 2.2.1 BKPM One Stop Service Related to Power Generation Business

One Stop Service Centeral  Level

BKPM

PLN

MEMR

Min. of Finance

National Land Agency

One Stop Service Provincial 

One Stop Service

Regency Level

1. Principle Permit/IUPL2. APIP (Inatrade)3. Import Duty Facility (DBC)*4. NIK (DBC)*5. Business Permits for Electricity Provision (IUPTL)6. Operation Permits7. Establishment of Business Area*on‐line by investor

1. RUPTL2. Procurement (Bidding, Direct Selection & Direct Appointment)3. PPA4. Financial Date

1. Registration SLO (Certificate Feasibility Operations) online

1. Letter of guarantee of feasibility

1. Technical Considerations2. Procurement of land (implementation stage)3. Certification

Min. of Forest & 

Environment

Min. of transportation

Min. of Economy

MIn. of Manpower

Min. of PublicWorks

1. IPKH2. AMDAL

1. Permit Special Terminal2. Permits Navigation3. Permit Railroad Crossing

1. Persetujuan PKLN

1. IMTA2. Boiler Operator License3. Permission transport aircraft4. Permit Lightning5. Health and Safety at Work Permit PLN

1. Permission Dam2. Construction Permit 

Local Govenment

1. Letters of support from local government* If the location of cross‐district / city permit required provincial level Locations

Local Govenment

1. IMB (Regency / City)                3. Permit Location (Regency / City)        5. TDP2. Environmental Permit              4. Permit Disorders

INVESTO

R

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2.3 CURRENT STATUS OF DEVELOPMENT POLICY FOR PROMOTION OF PRIVATE SECTOR PARTICIPATION ON SMALL HYDROPOWER BUSINESS

2.3.1 REGULATION OF THE MINISTRY OF ENERGY AND MINERAL RESOURCES

(1) Procedures for Small Hydropower Development

Indonesia is currently promoting private sector investment for small hydropower development through the

FIT system. The legal basis for this policy is the Regulation of the Minister of Energy and Mineral

Resources of Indonesia –Number 12 of 2014 (2 May 2014).

Private companies that apply for generation business through the FIT system need to submit the

following documents with their application prior to business commencement:

a. Overview of the company;

b. License documents based on laws and regulations from the government and local government;

c. Result of the pre-FS study confirmed by PLN;

d. Expected total investment amount;

e. Construction schedule until the commercial operation date (CoD);

f. Documents showing that land is available for the project;

g. Confirmation letter to make a deposit of 5% of the total investment amount within 30 business days after the decision of the business owner;

h. Document confirming the implementation of PPA issued by PLN; and

i. Confirmation letter that accepts the above conditions.

The project will follow the appraisal and approval processes based on these documents. This process

aimed to sort out the problematic projects and promote moving projects. The procedure for the

development process is presented in Figure 2.3.1:

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Source: Nippon Koei

Figure 2.3.1 Procedure for Small Hydropower Development

(2) Negative List

The latest version of the Investment Negative List, which entered into effect on 24 April 2014,

clarifies the situation regarding foreign direct investment (FDI) in the mini hydro sector. Under the

previous version of the list, such investment was stated as being 100% open to FDIs subject to a

“partnership arrangement” with a local firm.

However, as it was unclear what precisely was meant by a “partnership arrangement,” this tended to

discourage foreign investors. By contrast, the regulation states that the small hydro sector is now open up

to 49% FDI.

(3) Issues on Process of Appraisal and Approval

The current issues on the process of appraisal and approval for small hydro IPPs can be identified as

follows:

・ When a developer has an issue on debt financing, the developer recognizes that the period from the agreement of PPA to financial closure is short.

・ When the viability of a project has an issue on revenue and power tariff, the schedule for the feasibility study may be delayed.

・ A developer identified the need for PLN and MEMR to strengthen their coordination in providing a clear direction for the application of the regulations such as PPA.

years years

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2.3.2 PPA AND POWER TARIFF

In 2012, the MEMR issued t h e Ministry Decree No.4/2012 and fixed the purchase price of renewable

energy, which is aimed to enhance the development of renewable energy. Further, in 2014, a revision on

the portions of small hydropower was made through the Ministry Decree No.12/2014, and PLN has to

purchase power at a fixed price from small-scale IPPs having less than 10 MW. The Ministry Decree

No.12/2014 clearly shows procedures necessary for implementing small hydropower projects such as

required documents, permits, approvals, and necessary period. The fixed purchase price was increased in

the Ministry Decree No.12/2014, and the price was again raised in the Ministry Decree No.22/2014. In

the Ministry Decree No.22/2014, the fixed price was newly set for the project that harnesses existing

weir/dam facilities for small hydropower development.

In July 2015, the Ministry Decree No.19/2015 was issued and the FIT fixed price was again increased and

linked to US dollars. Now, the FIT fixed price is set to US dollars and the payment is made by Indonesian

rupiah. The fixed purchase price is US¢12.00/kWh for the first eight years and US¢7.5/kWh for the

succeeding period up to 20 years. These fixed prices shall be multiplied by the regional coefficient. The

fixed purchase prices are shown in Table 2.3.1 below.

Table 2.3.1 Power Purchase Price for Small Hydropower Project

Voltage/Capacity Feed-In-Tariff (US¢/kWh)

F Factor, depending on the location General Small Hydro Projects

Medium Voltage

(up to 10 MW)

Year 1 - 8 : 12.00 x F Java, Bali and Madura: 1.0 Sumatra: 1.1 Kalimantan and Sulawesi: 1.2 West and East Nusa Tenggara: 1.25 Maluku and North Maluku: 1.3 Papua and West Papua: 1.6

Year 9 - 20 : 7.50 x F

Low Voltage

(up to 250 kW)

Year 1 - 8 : 14.40 x F

Year 9 - 20 : 9.00 x F Source: Regulation of the Minister of Energy and Mineral Resources of Indonesia No. 19/2015

Table 2.3.2 below summarizes the FIT currently applicable to small hydropower projects utilizing

existing structures.

Table 2.3.2 Power Purchase Price for Small Hydropower Project Utilizing

Existing Structures

Voltage/Capacity

Feed-In-Tariff (US¢/kWh)

F Factor, depending on the location Small Hydro Projects Utilizing

Multipurpose Dams and/or Irrigation

Medium Voltage

(up to 10 MW)

Year 1 - 8 : 10.80 x F Java, Bali and Madura: 1.0 Sumatra: 1.1 Kalimantan and Sulawesi: 1.2 West and East Nusa Tenggara: 1.25 Maluku and North Maluku: 1.3 Papua and West Papua: 1.6

Year 9 - 20 : 6.75 x F

Low Voltage

(up to 250 kW)

Year 1 - 8 : 13.00 x F

Year 9 - 20 : 8.10 x F Source: Regulation of the Minister of Energy and Mineral Resources of Indonesia No. 19/2015

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Small hydropower projects under operation or the projects that have already concluded their contracts can

apply the tariff shown in Table 2.3.3.

Table 2.3.3 Power Purchase Price for Small Hydropower Project Under Operation or

Already Contracted PPA

Voltage/Capacity Feed-In-Tariff (US¢/kWh)

F Factor, depending on the location General Small Hydro Projects

Medium Voltage

(up to 10 MW) Year 1 - 20 : 9.30 x F

Java, Bali and Madura: 1.0 Sumatra: 1.1 Kalimantan and Sulawesi: 1.2 West and East Nusa Tenggara: 1.25 Maluku and North Maluku: 1.3 Papua and West Papua: 1.6

Low Voltage

(up to 250 kW) Year 1 - 20 : 11.00 x F

Source: Regulation of the Minister of Energy and Mineral Resources of Indonesia No. 19/2015

The salient features of the power tariff can be described as follows:

(1) No Escalation

The FIT regulation explicitly states that the prescribed FIT prices, as set out above, are not subject to any

escalation. The existence of this provision will prohibit parties to agree on any tariff escalation/indexation

in the PPA. Consistent with this restriction, the standard PPA as published by PLN does not provide for

any escalation mechanism. However, as the FIT price is on US dollar basis, the escalation risk becomes

less than that of the rupiah-based tariff.

(2) Transmission

The FIT price needs to include the costs of procuring the transmission lines connecting the plant to the

PLN grid. Accordingly, hydro plants that are located close to an adjacent grid will be at a significant cost

advantage. On the other hand, if the transmission line is long, a project has more exposure to land

acquisition risks and will be less competitive.

(3) Transitional Arrangement

Prices agreed for power supplied by small hydro plants prior to the coming into effect of the regulation

will continue to be governed by MEMR’s Regulation No.04/2012, No.12/2014, and No.19/2015.

However, prices may be adjusted upwards (except in the case of a plant that has reached the

commissioning stage) provided the project sponsor first secures a designation by the directorate as

hydropower producer. Such adjustment will be based on an agreement between PLN and the project

sponsor, but may not be higher than the weighted average price set out in the regulation, which is adjusted

based on voltage and location. The new price is fixed and must be directly set out in a PPA. It remains valid

for the duration of the PPA. The price adjustment process must be completed within 90 working days

upon the designation of the project sponsor as a hydropower producer. The adjusted price must also be

approved by the minister.

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Preparatory Survey on North Sumatra Mini 2-22 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(4) Hydropower Plants of More than 10 MW

The power tariff from hydropower plants of more than 10 MW is stipulated in the MEMR’s Regulation

No.03/2015. The power tariff is charged at a maximum of US¢9.00/kWh for 10 MW to 50 MW,

US¢8.50/kWh for 50 MW to 100 MW, and US¢8.00/kWh for more than 100 MW. The purchase price

is subject to the agreement between PLN and the developer.

2.3.3 REVISION OF PPA

PLN is currently revising the template of the PPA. The contents appear to be slightly modified compared

with the previous version. Out of the 315 projects that submitted their application, approximately half of

them have already signed the PPA. The major points can be identified and reviewed as follows:

(1) Termination of Agreement

The clause stipulates the conditions for contract termination. It raises the event when the buyer (PLN)

fails to make payment for three months. On the other hand, the penalty payment for PPA termination is

not mentioned. The event can be covered by the Civil Law of Indonesia (Clause No.1243), which

stipulates the claim for damages due to non-fulfillment of obligation.

(2) Supplemental Document

The PPA requires a certificate of cash deposit of 30% of the paid-in owned capital. This condition would

raise the hurdle for developers, and the developers may wish to discuss the condition.

2.3.4 PERMISSION/LICENSE REQUIRED FOR SMALL HYDROPOWER BUSINESS

In addition to the establishment of a special purpose company (SPC), the permissions and licenses

required for small hydropower business are as follows:

Table 2.3.4 Permission/License for Small Hydropower Business

No. Name Type Licenser

1 Izin Princip Development permission Local government

2 UKL and UPL Environmental permission Local government

3 Izin Lokasi Land acquisition license Local government

4 HGB Land register Local government

5 IMB Construction permission Local government

6 HO Obstacle permission Local government

7 SIPTPP River use permission River administrator

8 SIPPA Water use permission River administrator

9 HPO*) (Hydropower Operation License) Hydropower plan permission MEMR (EBTKE)

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Preparatory Survey on North Sumatra Mini 2-23 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

10 IUPTLS Provisional electricity license MEMR (Kelistrikan)

11 IUPTL Electricity business license MEMR (Kelistrikan)

*) Tentative name because there is no official name Source: ESDM

• No.1 to No.8 can be processed in parallel and the period is estimated to be around nine months.

• No.2 (UKL and UPL) is usually prepared during the pre-FS stage.

• After No.3 (Izin Lokasi), land acquisition is carried out and then HGB is obtained.

• For application of No.9 (HPO), No.1, pre-FS report and No.3-N.8 are required.

In case that the project area includes public forest, Izin Penggunaan Kawasan Hutan (Forest Use

Permission) from the Ministry of Forest is required.

2.3.5 DEVELOPMENT STATUS OF SMALL HYDROPOWER

(1) Hydropower Potential

In 1999, World Bank conducted a study4 to identify the hydropower potential in Indonesia. In the study,

hydropower potential amounting to 22.0 GW passed the third screening including planning and

implementation. Furthermore, the Indonesia Hydropower Master Plan in 2011 estimated that a potential

capacity of 14.6 GW will be implemented until 2027. According to RUPTL (2015-2024), the potential of

renewable energy is as follows:

Table 2.3.5 Renewable Energy Potentials

No. New and Renewable

Energy Potential

1 Geothermal 29,164 MW

2 Hydro 75,000 MW

3 Biomass 49,810 MW

4 Solar Power 4.80 kWh/m2/day

5 Wind Power 3-6 m/s

6 Ocean 49 GWSource：RUPTL 2015-2024

Table 2.3.6 Development Plan of Renewable Energy

*Megawatt Peak: Watt value under the standard condition Source: RUPTL 2015-2024

4 World Bank: “Hydro Inventory and Pre-Feasibility Study”, 1999

No Power Type Unit 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Total

1 Mini Hydro MW 67 40 156 172 123 135 272 297 130 150 1,542

2 Solar MWp* 6 20 25 30 35 35 35 40 45 50 321

3 Wind MW ‐             40 40 40 40 40 50 50 50 50 400

4 Biomass MW 15 30 40 50 50 50 50 50 50 50 435

5 Ocean MW ‐             1 1 3 3 5 5 5 5 10 38

Total MW 88 131 262 295 251 265 412 442 280 310 2,736

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Preparatory Survey on North Sumatra Mini 2-24 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The accumulated planned generating capacity for each generation type is shown in Figure 2.3.2. As

shown in the figure, the small hydropower has important role for renewable energy development as it has

56% of the planned renewable energy development.

Source: RUPTL 2015-2024

Figure 2.3.2 Planned Accumulated Renewable Energy Generation Capacity

In the JICA study, namely, “Survey for Enhancement of Private Sector Investment on Small Hydropower

IPP Projects in Indonesia”(2015), it was reported that there were 318 small hydropower projects that

submitted their application for selling electricity with the FIT price system. The status of the 318 projects

is as follows: 49 projects are under operation, 49 projects are under construction, and 220 projects are at

the stage before financial closure.

0

500

1,000

1,500

2,000

2,500

3,000

2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

Accumulative

 Additional Capacity 

(MW)

Year

Ocean

Biomass

Wind

Solar

Mini Hydro

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Preparatory Survey on North Sumatra Mini 2-25 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.3.7 Status of Small Hydropower Development (As of February 2015)

Source: PLN

2.3.6 ISSUES ON SMALL HYDROPOWER DEVELOPMENT

As a result of the introduction of FIT for small hydropower sector, and further increasing FIT fixed price

linked to US dollar, small hydropower development becomes an attractive business for small hydropower

developers. On the other hand, it is recognized that small hydropower business promotion is always

associated with various risks such as construction risk. According to the JICA study on the “Survey for

Enhancement of Private Sector Investment on Small Hydropower IPP Projects in Indonesia” (2015), the

following risks are described for small hydropower development:

(1) Construction Risk

The construction risk, which may have the most significant impact on the profitability of the project, is

affected by the initial capital expenditure (CAPEX) for the construction of the IPP facilities because the

revenue side of the cash flow is practically assured under the FIT system. It should be noted that

insufficiency in feasibility study (FS), basic/detailed design, and capability of contractor cause serious

problems of cost overrun of the construction. Particularly in Indonesia, this risk is relatively higher than

in the developed countries. Well prepared FS and basic/detailed design, and careful selection of high

quality contractor are indeed important to mitigate the risk.

For the contract form, the lender generally prefers the EPC full turnkey contract as this type of contract

transfers all risks of cost and construction time to the contractor and does not allow the contractor to

recover cost overrun and modify the completion date.

Status Number Capacity (kW)

Indonesia Timur 84 305,720

Operation 21 59,840

Construction 11 39,700

Financing Proces 7 32,700

PPA Process 21 88,330

Proposal 24 85,150

Jawa Bali 114 413,885

Operation 17 17,870

Construction 15 60,070

Financing Proces 10 62,620

PPA Process 33 111,206

Proposal 39 162,119

Sumatera 120 713,730

Operation 11 37,625

Construction 23 156,458

Financing Proces 26 162,948

PPA Process 27 185,700

Proposal 33 170,999

Grand Total 318 1,433,335

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Preparatory Survey on North Sumatra Mini 2-26 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

However, as private sector infrastructure projects are financed through corporate finance scheme, and the

construction contract is generally a unit price contract, payment is made by the actual quantity with unit

price. The JICA Survey Team interviewed the contractors in Indonesia, and it was found out that the EPC

contract in Indonesia is generally a unit price contract although it is stated as an EPC contract.

(2) Drought, Flood, and Discharge Risks

In order to ensure the revenue in the cash flow projection, it is important to take into account the drought,

flood, and other discharge risks in small hydropower IPP projects. Sometimes, sufficient discharge data

may not be available in small rivers for small hydropower IPPs, and practical treatment should be made

on a case-by-case basis by referring to similar projects. Engineering analysis with regard to the discharge

risks is important, but it is also worth considering a financial solution such as increasing the provision for

the debt service reserve account in order to cover the drought risk for one or two years.

(3) Other Risks

Other risks associated with the small hydropower development are as follows:

- Risks related to PPA to be signed with PLN;

- Sponsor risks of the developers;

- Legal risks for real estate-related contract, water utilization and other licenses including those by the local government;

- Environmental and social risks; and

- Ability to properly respond to an accident or natural disaster.

2.4 STATUS OF POWER SUPPLY AND POWER DEVELOPMENT PLAN IN NORTH SUMATRA

2.4.1 CURRENT STATUS OF POWER SUPPLY IN NORTH SUMATRA

(1) Outlook of Power Supply and Demand in North Sumatra

The current power grid of North Sumatra, which consists of 150 kV and 275 kV transmission lines, is

connected to the neighboring provinces of Ache and Riau via the 150 kV transmission line. The power

grid and existing and planned power stations are shown in Figure 2.4.1.

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Preparatory Survey on North Sumatra Mini 2-27 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: RUPTL 2015-2024

Figure 2.4.1 Power Grid and Existing and Planned Power Stations

PLN’s power stations in North Sumatra are under the control of North Sumatra Generation Unit

(Sumbagut). The power supply system of Sumbagut is divided into six power sectors, where four of them

cover the power supply for North Sumatra. The power sector in North Sumatra Generation Unit is shown

in Figure 2.4.2.

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Preparatory Survey on North Sumatra Mini 2-28 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: Website of PT PLN (Persero) Pembangkitan Sumatera Bagian Utara

http://www.pln.co.id/kitsbu/wilayah-kerja/

Figure 2.4.2 Power Sector in North Sumatra Generation Unit

The power sectors that cover North Sumatra are Belwan, Medan, Pandan, and Labuhan Angin. The

capital of North Sumatra is Medan, and the population of the city is ranked fourth in the entire Indonesia.

The city consumes 60% of the total electricity demand in North Sumatra. According to RUPTL, the rapid

demand growth of Medan leads to power supply deficit in the region, and PLN has to limit the number of

new demand connections to suppress the demand growth. RUPTL 2015-2025 describes another issue of

power supply that there is a problem of low quality of electricity supply due to voltage drop. RUPTL

explained that the length of the distribution line is too long to stabilize the voltage.

In order to overcome these situations, RUPTL explained that urgent power station construction is

necessary to catch up with the growing demand and by constructing 150 kV line to stabilize the voltage.

(2) Power Demand in North Sumatra

According to RUPTL 2015-2024, the peak electricity demand in North Sumatra reaches to 1,450 MW and

the power is supplied by power stations controlled by the four power sectors as well as interchange from

Ache and the private sector such as PT. Inarum. Small hydropower stations, geothermal IPPs, and other

small-scale IPPs supply electricity through the distribution line (22 kV).

According to PLN statistics, the electric energy consumption in North Sumatra in 2014 is estimated to be

8,271 GWh, and the electric energy consumption by type of users is shown in Table 2.4.1.

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Preparatory Survey on North Sumatra Mini 2-29 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.4.1 Electric Energy Consumption by Type of Users in North Sumatra in 2014

Source: PLN Statistics 2014

(3) Power Supply Capacity in North Sumatra

Power stations that are currently being operated in North Sumatra are shown in Table 2.4.2. As shown in

the table, the installed capacity of the power stations in North Sumatra is 2,487.2 MW, but the net

capacity, which is effective capacity for power supply, is reduced to 1,872.4 MW. Considering that the

peak demand in 2014 was 1,450 MW and net power supply capacity was 1,872.4 MW, the reserve margin

is calculated at 29%. According to RUPTL 2015-2024, PLN targets the Loss of Load Probability (LOLP)

at 0.274% and this requires 35% of reserve margin. The current reserve margin of 29% does not satisfy

the PLN target and securing reserve capacity is also an issue on the PLN’s power generation expansion

plan.

Residential Industrial Business SocialGov. Office

Building

Public Street

LightsTotal

Energy Consumption

(GWh)4,177 2,094 1,252 255 97 396 8,271

Ratio (%) 50.5% 25.3% 15.1% 3.1% 1.2% 4.8% 100%

50.5%

25.3%

15.1%

3.1% 1.2% 4.8%

Residential

Industrial

Business

Social

Gov. Office Building

Public Street Lights

Energy Consumption by  Type of Customer

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Preparatory Survey on North Sumatra Mini 2-30 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.4.2 Power Stations Currently Operated in North Sumatra

Source: RUPTL 2015-2024

Powerstations Type Type OwnerInstalled Capacity

(MW)

Net Capacity

(MW)

I BELAWAN SECTOR 1527.3 1092.4

1 PLTU Belawan #1 PLTU HSD PLN 65 40

2 PLTU Belawan #2 PLTU HSD PLN 65 32.5

3 PLTU Belawan #3 PLTU HSD PLN 65 33.5

4 PLTU Belawan #4 PLTU HSD PLN 65 44.4

5 PLTGU Belawan GT 1.1 PLTGU HSD PLN 117 81

6 PLTGU Belawan GT 1.2 PLTGU HSD PLN 128.8 81

7 PLTGU Belawan ST 1.0 PLTGU HSD PLN 149 50

8 PLTGU Belawan GT 2.1 PLTGU HSD PLN 130 118

9 PLTGU Belawan GT 2.2 PLTGU HSD PLN 130 100

10 PLTGU Belawan ST 2.0 PLTGU HSD PLN 162.5 112

11 PLTG Belawan (TTF) PLTG HSD PLN 120 70

12 PLTMG Belawan PLTG HSD Lease 40 40

13 PLTD Sewa Belawan MFO PLTD MFO Lease 120 120

14 PLTD Sewa Tersebar 150 MW (BIO FUEL) PLTD HSD Lease 150 150

15 PLTD Sewa Glugur 20 MW PLTD HSD Lease 20 20

II MEDAN  SECTOR 225.8 192.2

1 PLTG Glugur (TTF) PLTG HSD PLN 11.9 11

2 PLTG Paya Pasir #7 (TTF) PLTG HSD PLN 34.1 34

3 PLTD Titi Kuning #1 PLTD HSD PLN 4.1 2.5

4 PLTD Titi Kuning #2 PLTD HSD PLN 4.1 2

5 PLTD Titi Kuning #3 PLTD HSD PLN 4.1 2.5

6 PLTD Titi Kuning #4 PLTD HSD PLN 4.1 3

7 PLTD Titi Kuning #5 PLTD HSD PLN 4.1 2.5

8 PLTD Titi Kuning #6 PLTD HSD PLN 4.1 2.7

9 PLTD Sewa Paya Pasir (Arti Duta) PLTD HSD rent 30 11

10 PLTD Sewa Paya Pasir #2 (BGP) PLTD HSD rent 40 40

11 PLTD Sewa Paya Pasir #3 (BUGARAWA) PLTD HSD rent 20 16

12 PLTD Sewa Belawan (AKE) PLTD HSD rent 65 65

III PANDAN  SECTOR 139.6 125

1 PLTMH Total PLTA Air PLN 7.6 5

2 PLTA Sipansihaporas #1 PLTA Air PLN 33 33

3 PLTA Sipansihaporas #2 PLTA Air PLN 17 17

4 PLTA Lau Renun #1 PLTA Air PLN 41 30

5 PLTA Lau Renun #2 PLTA Air PLN 41 40

IV LABUHAN ANGIN  SECTOR 230 120

1 LABUHAN ANGIN # 1 PLTU Batubara PLN 115 50

2 LABUHAN ANGIN # 2 PLTU Batubara PLN 115 70

V IPP 180 170

1 Asahan I.1 PLTA Air IPP 90 85

2 Asahan I.2 PLTA Air IPP 90 85

VI Lease from Inalum and Excess Power 184.5 172.8

1 INALUM PLTA Air rent 90 90

2 PLTP SIBAYAK PLTP GEO rent 10 3

3 PLTMH Parlilitan PLTA Air rent 7.5 8

4 PLTMH Sei Silau 2 PLTA Air rent 8 8.8

5 PLTMH Parluasan PLTA Air rent 5 5

6 PLTMH Hutaraja PLTA Air rent 5 5

7 PLTMH KARAI 13 PLTA Air rent 5 5

8 PT GSI‐1 (Excess Power) PLTD HSD rent 6 ‐

9 PT GSI‐2 (Excess Power) PLTD HSD rent 9 9

10 PT Pertumbuhan Asia (Excess Power) #1 PLTD HSD rent 10 10

11 PT Pertumbuhan Asia (Excess Power) #2 PLTD HSD rent 10 10

12 PT Inalum Porsea (Excess Power 2 MW) PLTD HSD rent 2 2

13 PT Nubika (Excess Power GI R. Prapat) PLTD HSD rent 6 6

14 PT Victorindo (Excess Power GI Sidempuan) PLTD HSD rent 5 5

15 PT Harkat Sejahtera (GI P.SIANTAR) PLTD HSD rent 1 1

16 PTPN III Sei Mangkai (GI KISARAN) PLTD HSD rent 3 3

17 PT Evergreen (Excess Power GI T. Morawa) PLTD HSD rent 2 2

Total 2487.2 1872.4

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Preparatory Survey on North Sumatra Mini 2-31 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The abbreviations of power generation type shown in Table 2.4.3 are as follows:

Table 2.4.3 Abbreviation of Generation Type Used by PLN

Source: RUPTL 2015-2024

2.4.2 POWER DEMAND PROJECTION OF NORTH SUMATRA

In RUPTL 2015-2024, the power demand in North Sumatra is projected based on the economic growth

and population growth. The projected power demand in North Sumatra presented in RUPTL 2015-2024 is

shown in Table 2.4.4.

Table 2.4.4 Power Demand Projection in North Sumatra

Year  Energy SalesEnergy 

Production Peak Load 

  (GWh) (GWh)  (MW) 

2015 9,293 10,244 1,886

2016 10,374 11,426 2,054

2017 11,597 12,754 2,189

2018 13,002 14,283 2,398

2019 14,623 16,046 2,636

2020 16,445 18,031 2,899

2021 18,674 20,465 3,222

2022 21,321 23,351 3,602

2023 24,436 26,746 4,125

2024 28,090 30,728 4,676

Growth Rate  13.10% 13.00% 10.60%

Source: RUPTL 2015-2024

As shown in the table, the power demand of North Sumatra is projected with high annual growth rate of

13.0%. According to RUPTL 2015-2024, the power demand projection of Indonesia is estimated between

8.4% and 9.0%, and that of Sumatra is in the range from 11.7% to 12.2 %. This fact indicates that North

Sumatra has faster growth rate of power demand than that of other provinces in Sumatra and the average

of Indonesia.

According to RUPTL, residential use has the largest electricity consumption as it shares around 60% of

the total demand of Sumatra. Other major consumption of electricity is business, industry, and public use.

Abbr. Full name English

PLTA  : Pusat Listrik Tenaga Air  Hydropower (middle and large scale)

PLTB : Pusat Listrik Tenaga Bayu  Wind power

PLTD : Pusat Listrik Tenaga Diesel Diesel

PLTG  : Pusat Listrik Tenaga Gas Gas turbine

PLTGU : Pusat Listrik Tenaga Gas & Uap Combined cycle

PLTM/MH : Pusat Listrik Tenaga Mini/Mikro Hidro Mini/Micro Hydrp

PLTMG  : Pusat Listrik Tenaga Mesin Gas Gas Engine

PLTN : Pusat Listrik Tenaga Nuklir Nuclear

PLTP  : Pusat Listrik Tenaga Panas Bumi Geothermal

PLTS : Pusat Listrik Tenaga Surya Solar Power

PLTU : Pusat Listrik Tenaga Uap Steam

PTMPD : Pembangkit Termal Modular Pengganti Diesel Modular Replacement Diesel

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Preparatory Survey on North Sumatra Mini 2-32 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The details of the type of use for the projected power demand of North Sumatra are not shown in RUPTL.

2.4.3 GENERATION EXPANSION PLAN IN NORTH SUMATRA

According to RUPTL 2015-2024, North Sumatra has abundant substation natural resources for power

generation, especially for hydropower and geothermal power. RUPTL 2015-2024 explains about the

necessary expansion plan of generating capacity, substation, and transmission line, and necessary

investment cost.

Table 2.4.5 Necessary Expansion for Generation Capacity, Transmission, and Substations

between 2015 and 2024

Source: RUPTL 2015-2024

As shown in the table, North Sumatra needs an additional 5,186 MW in ten years from 2015. PLN

formulates the generation expansion plan of North Sumatra based on the planned facilities investment as

shown in Table 2.4.6.

YearAdding

CapacitySub Station

Tranmission

Line

Investment

Cost

(MW) (MVA) (km) (106 USD)

2015 231 1,700 1,154 6592016 441 840 976 5872017 272 1,140 395 8092018 970 880 596 1,6812019 914 310 226 1,1492020 100 840 890 6632021 250 240 162 6062022 688 480 44 1,1352023 910 680 150 1,5142024 410 700 ‐ 711

Total 5,186 7,810 4,593 9,514

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Preparatory Survey on North Sumatra Mini 2-33 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 2.4.6 Generation Expansion Plan of North Sumatra

Source: RUPTL 2015-2024

As shown in the table, the planned PLN generation capacity is 3,304 MW and this indicates that the PLN

planned capacity is not able to cover the required capacity of 5,186 MW. Generation expansion by IPPs is

indispensable for generation expansion in North Sumatra. The planned generation expansion for each

power generation type is shown in Table 2.4.7.

Table 2.4.7 Necessary Investment of Generation Capacity from 2015 to 2024

Source: RUPTL 2015-2024

As shown in the table, majority of generation expansions are large-scale hydropower and steam power

plants such as coal-fired power plant. Then, geothermal and combined cycle and gas turbine power

No Project Type OwnerCapacity

(MW)COD

1 Pangkalan Susu #2 (FTP1) PLTU PLN 440 2015

2 PLTMH Tersebar Sumut PLTM IPP 10.9 2015

3 Truck Mounted Sumut PLTG/MG PLN 100 2016

4 Barge Mounted Sumut PLTG/MG PLN 250 2016

5 Mobile PP Nias PLTG/MG PLN 25 2016

6 Nias (FTP2) PLTU PLN 7 2016

7 Wampu (FTP2) PLTA IPP 45 2016

8 PLTMH Tersebar Sumut PLTM IPP 63 2017

9 PLTMH Tersebar Sumut PLTM IPP 98.7 2017

10 Sarulla I (FTP2) PLTP IPP 330 2017‐2018

11 Pangkalan Susu #4 (FTP2) PLTU PLN 200 2018

12 Sumbagut‐1 Peaker PLTGU/MGU PLN 250 2018

13 Sumut‐1 PLTU IPP 300 2018

14 Asahan III (FTP2) PLTA PLN 174 2019

15 Hasang (FTP2) PLTA IPP 40 2019

16 Pangkalan Susu #3 (FTP2) PLTU PLN 200 2019

17 Sumbagut‐3 Peaker PLTGU/MGU PLN 250 2019

18 Sumbagut‐4 Peaker PLTGU/MGU PLN 250 2019

19 Nias PLTMG PLN 20 2020

20 Sorik Marapi (FTP2) PLTP IPP 240 2020‐2021

21 Simonggo‐2 PLTA PLN 90 2021

22 Batang Toru (Tapsel) PLTA IPP 500 2022

23 Kumbih‐3 PLTA PLN 48 2022

24 Sibundong‐4 PLTA IPP 120 2022

25 Sipoholon Ria‐Ria (FTP2) PLTP IPP 20 2022

26 Simbolon Samosir (FTP2) PLTP IPP 110 2023

27 Sumatera Pump Storage‐1 PLTA PLN 500 2023

28 Sumut‐2 PLTU IPP 600 2023 ‐ 2024

29 Sarulla II (FTP2) PLTP IPP 110 2024

30 Sumatera Pump Storage‐2 PLTA PLN 500 2024

PLN Total 3,304

IPP Total 2,588

PLN + IPP Total 5,892

Generation Type Capacity (MW)

Hydropower PLTA 2,017

Geothermal PLTP 810

Gas turbine PLTG/MG 395

Combined cycle PLTGU/MGU 750

Steam PLTU 1,747

Mini Hydro PLTM 173

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Preparatory Survey on North Sumatra Mini 2-34 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

stations follow.

2.4.4 ISSUE OF POWER SUPPLY AND DEMAND BALANCE IN NORTH SUMATRA

As described in the preceding chapter, the ten year electricity demand projection of North Sumatra from

2015 is estimated at an annual growth rate of 13.0% of electric energy consumption, and 10.6% of peak

power demand, and these figures are higher than those of other provinces in Indonesia. In order to catch

up with this rapid growth of electricity demand, additional generation capacity of 5,186 MW is needed for

ten years from 2015. This requires large-scale 500 MW power plants to be constructed every year.

Meanwhile, the South Sumatra Generation Unit (Sumbagsel) has power supply surplus against the power

demand in the service area; however, only limited amount of surplus electricity can be transferred to

North Sumatra due to constraints in the transmission line capacity. Therefore, power deficit is worsening

and the rapid growth of electricity demand in North Sumatra should be addressed by the expansion of

generation capacity of the North Sumatra Generation Unit and IPPs.

Currently, as the power supply capacity cannot fulfill the demand in North Sumatra, PLN limits the

number of new connections of electricity users. In 2014, the number of applicants who are waiting for

connection to PLN power supply was 14,346 and 70.6 MVA is needed; hence, these numbers are

increasing annually. Under these circumstances, North Sumatra needs additional generation capacity as

soon as possible to solve the issue of power deficit and catch up with the rapid demand growth.

2.5 SIGNIFICANCE OF THE PROJECT IN NORTH SUMATRA

2.5.1 EFFECT OF THE PROJECT TO POWER SUPPLY AND DEMAND BALANCE IN NORTH SUMATRA

The combined capacity of the two mini hydropower projects in North Sumatra is approximately 20 MW.

This accounts to just 1% of the total necessary additional generation capacity of 5,892 MW and 11.6% of

the planned additional mini hydropower generating capacity of 173 MW.

The estimated electrical energy production of the two mini hydropower projects is 144.4 GWh.

According to the statistics of North Sumatra, the electrical energy consumption per household is 1,458.8

kWh/year. This means that the project can afford to supply electricity to around 99,000 households

(around 425,700 persons, calculated from the average of 4.3 person per household in North Sumatra). The

population of North Tapanuli Regency is 286,000 persons, and the neighboring Central Tapanuli Regency

has a population of 268,000. Therefore, the project can serve electricity to 78% of the two regencies

combined.

It can be concluded that although the impact of the project to the power supply system in North Sumatra

is limited, the impact to the distribution level, where the projects will connect to, is significant as the

project can supply electricity to almost 80% of the population of the two regencies.

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Preparatory Survey on North Sumatra Mini 2-35 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

2.5.2 SIGNIFICANCE OF THE PROJECT TO THE POWER SYSTEM IN NORTH SUMTRA

As described in the previous chapter, the project will have a large positive impact to the region as the

project can serve almost 80% of the population of the two regencies. As North Sumatra has abundant

hydropower potential, developing small hydropower by harnessing rich hydropower potential will

contribute to reinforcing the power supply in the project area. This will finally contribute to the economic

development in the region.

Moreover, power development through small hydropower conforms to the national policy of expediting

renewable energy as clean energy with low carbon dioxide emissions.

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Preparatory Survey on North Sumatra Mini 2-36 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(Blank Page)

Final Report

Preparatory Survey on North Sumatra Mini 3-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 3 SITE CONDITIONS

3.1 SITE CONDITIONS

The Project is located in the province of North Sumatra, which stretches across the island of Sumatra

between the Indian Ocean and the Strait of Malacca. It borders Aceh Province in the northwest and Riau

and West Sumatra provinces in the southeast. The province contains a broad and low plain along the

Strait of Malacca Coast, the provincial capital, Medan, is located in the north coastal plain. In the south

and west, the land rises to the mountain range that runs the length of Sumatra; the mountains are

dominated by Lake Toba, formed by the caldera of an ancient volcano. The province of North Sumatra

has a land area of 71,680 km2. Pattern of land use in this province is characterized by relatively large area

for agricultural sector (mostly plantation), followed by forest.

The project area is located in North Sumatra Province, and mostly mountainous area covered by

production forests. Rubber plantation fields are also sparsely located on the flatter slope lands along the

existing roads and villages. The existing power line is available along the existing public roads between

Kolang and Pargaringan and between Tarutung and Pancurbatu, but the project area is unelectrified area

and no grid connection to the existing power line.

The Poring River originates from the mountainous area in southwest Tarutung, which elevation ranges

between 1,100-1,200 meters above sea level (masl), and flows along a gorge and meets the Sibundong

River at a length of about 20 km from the sources. Then, the Sibundong River flows into the Indian

Ocean at a length of about 42 km.

Source: JICA Survey Team

Figure 3.1.1 River Profile of the Poring River

Intake-1EL.646.5

Head Tank-1EL.641.0

Powerhouse-1EL.442.0

(Intake-2)EL.441.6

Head Tank-2EL.436.5

Powerhouse-2EL.192.1

Footpath Bridge

EL.675.0

Poring BridgeEL.350.0

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600

700

800

-1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000

Elev. (m)

River Station starting from Footpath Bridge (m)

Poring River Profile

Hydropower Facility

Poring-1 Small Hydro Project Poring-2 Small Hydro Project

SibundongRiver

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Preparatory Survey on North Sumatra Mini 3-2 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The project aims to generate hydropower energy by utilizing the difference of the river elevation of 450 m

in the 5-km long section of the Poring River before the confluence to the Sibundong River. Cascade

waterfalls start from the Poring-1 Intake to the confluence of the Sibundong River. According to the

counter map from satellite, the elevation of the river is 645 m in Poring-1 Intake, 442 m in Poring-1

Powerhouse, 442 m in Poring-2 Intake and 192 m in Poring-2 Powerhouse.

3.2 ACCESS TO THE SITE

The project is located in North Tapanuli Regency in North Sumatra Province, 20 km westward of

Tarutung, which is the regency capital of Tapanuli Utara, and 25 km northward of Sibolga, which is the

regency capital of Central Tapanuli. The following two accesses are currently available to reach the

project site:

Route-1: Sibolga – Kolang – Project Site: 40 km (2.0 hours drive by 4WD car)

The road from Sibolga to Kolang (25 km long) is a provincial road and paved in an excellent condition.

Then, the road branches in Kolang to the project site with regional road about 3.0 m wide, which is paved

but potholed. The road condition, particularly in the last 5.0 km close to the project site, is extremely

steep and poor and hard for driving without using a 4WD vehicle.

Route-2: Tarutung – Pancurbatu – Project Site: 30 km (3.0 hours drive by motorbike)

The road from Tarutung to Hutaraja (3 km long) is also a provincial road and paved in an excellent

condition. Then the road branches in Hutaraja to Pancurbatu (8 km long) which is a regional road,

partly potholed but still in good condition. The remaining road to the project site (20 km long) is only

passable by motorbikes (mostly unpaved road but partly paved by stone pitching and asphalt).

It is noted that this road was originally planned by the PU regional office and started the excavation

works in 2000 but was not completed because of budget shortage according to the village people.

Therefore, this route will also be accessible to the project site by improving the steep longitudinal profile

and narrow cross sections.

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Preparatory Survey on North Sumatra Mini 3-3 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 3.2.1 Location Map of the Project

Route-1 Existing Public Road near the Project Area Route-2 Existing Bike Road near Tarutung Source: JICA Survey Team

Figure 3.2.2 Conditions of the Existing Public Road

3.3 TOPOGRAPHY

3.3.1 TOPOGRAPHY OF THE SITE

North Tapanuli Regency is located in the North Sumatra highlands at an altitude between 300-1500 masl.

Topography and terrain of North Tapanuli District is relatively flat variegated (3.16%), ramps (26.86%),

oblique (25.63%), and steep (44.35%).

In the geographic coordinate system, North Tapanuli is in the position of 1 ° 20 '- 2 ° 41' north latitude

and 98 ° 05'm - 99 ° 16' east longitude. As for the geographical location, North Tapanuli District is

flanked or directly adjacent to five districts, namely, in the north bordering the Toba Samosir Regency, in

the east by Labuhan Batu District, in the south by South Tapanuli District, and in the west by the District

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Preparatory Survey on North Sumatra Mini 3-4 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Humbang Hasundutan and Central Tapanuli.

3.3.2 TOPOGRAPHIC SURVEY

(1) Available Topographic Data

1) Background of Additional Survey

In the course of the study, the topographic survey and mapping were carried out to obtain the topographic

data/information and survey products as topographic maps required for the Project not only on the overall

project area but also on each structure, i.e., intake weir site, headrace channel, head tank, penstock,

powerhouse, access roads, temporary construction yard, and transmission line.

The topographic survey and mapping were conducted by PT. Geomarinedex (Subcontractor) under the

supervision of the JICA Survey Team. The survey and mapping works started on 26 March 2015 and

were completed on 29 June 2015 after receiving their final report.

2) Topographic Information and Data

During the study period, the JICA Survey Team collected the available topographic data related to the

project area as shown in Table 3.3.1 below, which were used for site reconnaissance and preliminary

design.

Table 3.3.1 Available Topographic Data

Data Scale Remark

1 Topographic map with 25 m contour interval 1/50,000 Covers the whole project area

2 Digital elevation model (DEM) from ALOS1 1/25,000 Covers the whole project area Source: JICA Survey Team

(2) Topographic Survey

1) Scope of the Topographic Survey

The scope of work for the new topographic survey and mapping are shown in the table below:

The Subcontractor executed the topographic survey and mapping for the following areas:

a. All Hydropower Facility Site: 1/1,000 scale map

b. Major Facility Site, 1:100 scale map: Intake Weir-1, Head Tank-1, Powerhouse-1, Intake Weir-2, Head Tank-2, and Powerhouse-2

c. Existing Public Road Improvement Site (Preparatory Works): 1/1,000 scale map

d. River Cross Section Survey: 4-No for Intake Weir-1, 5-No for Powerhouse-1, 4-No for Intake Weir-2, and 5-No for Powerhouse-2

1 ALOS (Advanced Land Observing Satellite / Daichi) is a Japanese Earth-observation satellite, developed by the Japan

Aerospace Exploration Agency (JAXA), to obtain a data with sufficient resolution to be able to generate 1:25,000 scale maps, but

unables to observe land surface conditions by penetrating vegetation such as forests.

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The locations of the above survey and mapping areas are shown in the following figure.

Table 3.3.2 Scope of New Topographical Survey and Mapping Item Unit Quantity Scale Remarks

Poring-1 Intake ha 1.5 1/100 Head Tank ha 1 1/100 Powerhouse ha 1 1/100 Intake ha 14.5 1/1,000 Waterway ha 22.5 1/1,000 Head Tank and Penstock ha 18 1/1,000 Powerhouse ha 4 1/1,000 Excluding 8 ha for Poring-2 Intake

Poring-2 Intake ha 2.5 1/100 Head Tank ha 1 1/100 Powerhouse ha 1 1/100

Intake ha 8 1/1,000 Excl. 4 ha for Poring-1

Powerhouse Waterway ha 23.5 1/1,000

Head Tank, Penstock, Powerhouse

ha 39.5 1/1,000

Total Area of Topographic Survey ha 138 - 8 ha (1/100 scale), 130 ha (1/1,000)Access Road

Route Survey km 23 - Cross Section Survey No 1,150 - Current road width, every 20 m,

River Cross Section Survey No 18 - 9 Nos (Poring-1), 9 Nos (Poring-2)Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.3.1 Location Map of the Survey and Mapping Area

2) Benchmarks

The national benchmark obtained from the National Survey Mapping Agency (Badan Informasi

Geospasial: BIG) isshown in Table 3.3.3. The benchmark is located in the yard of Post Office (Kantor

Pos & Giro) Pandan, about 9 km in the southwest side of Sibolga City, Jalan Padang Sidempuan- Sibolga

km 78+500.

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Table 3.3.3 National Benchmark for the Topographic Survey

ID Geodetic Coordinates (WGS84 Datum) UTM Coordinates, Zone 48 South Elevation

Latitude Longitude E. Height East (X) North (Y) Scale Factor MSL Datum

N.1045/

TTG-864

1°41’

13.7520”N

98°49’

07.7021”E

-9.631 m 479,846.309

m

186,482.616

m

0.999605 3.042 m

Source: National Survey Mapping Agency (Badan Informasi Geospasial: BIG)

Six project benchmarks were established within the project area with reference to the national benchmark.

Their XYZ coordinates were surveyed by using geodetic global positioning system (GPS) receiver with

static baseline measurements by means of tied survey to determine the coordinate horizontal and vertical

control points. Furthermore, 12 project benchmarks were additionally established along the 17-km access

road from Tarutung in the same method.

Table 3.3.4 Coordinates of Project Benchmarks

ID UTM, Zone 47 North TTG

ID UTM, Zone 47 North TTG

Northing (m) Easting (m) MSL Datum Northing (m) Easting (m) MSL Datum

PR-01 216,777.224 474,452.337 413.337 PR-10 217,519.345 481,228.617 848.520

PR-02 216,818.588 474,480.567 420.460 PR-11 216,498.255 484,901.095 1,031.491

PR-03 217,087.808 475,603.194 693.662 PR-12 216,504.325 484,959.293 1,024.679

PR-04 217,796.596 475,416.754 459.084 PR-13 216,351.030 489,091.094 1,030.869

PR-05 217,917.492 477,468.628 703.308 PR-14 216,394.104 489,175.650 1,042.057

PR-06 217,891.129 477,536.105 716.995 PR-15 218,525.678 491,731.220 1,190.784

PR-07 216,823.227 473,393.303 209.703 PR-16 218,600.085 491,767.843 1,189.924

PR-08 216,739.282 473,359.957 194.543 PR-17 220,014.447 495,182.559 1,058.197

PR-09 217,492.780 481,193.449 848.150 PR-18 220,119.610 495,223.714 1,060.799 Source: Topographic Survey Report by PT. Geomarindex

The benchmarks were surveyed by traversing and levelling survey measurements. The traversing survey

measurement was done by using a total station to distribute the deviation of horizontal angle within the

specified standard for both inside and outside angles. The levelling survey measurement was by automatic

levelling equipment to make a closed loop or tied at both ends to satisfy the standard.

3) Topographic Map

Data processing was carried out to draw the contour maps below by using AutoCAD Civil 3D for the data

of GPS measurement, traversing, leveling, and detailed topographic spot height. Data verification was

also performed to review the quality and accuracy to comply with the tolerance specified in the typical

standard.

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Preparatory Survey on North Sumatra Mini 3-7 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

3.4 HYDROLOGY

3.4.1 STUDY AREA

(1) River Basin Characteristics

As shown in the location map in Figure 3.4.1, the Poring

River and its longest tributary, the Batutunggal River,

originate from the peaks of Mt. Tor Tunjul at El.1,534 m

and Mt. DK. Siborboron at El.1,480 m, about 5 km west

of Tarutung Town, and flow from the east to southwest

through forest and mountainous areas. Joined by the

Batutunggal River at El.750 m, the Poring River enters

into the gorge at around El.625 m where the proposed

project site near Siantar Naipospos Village exists and

merges with the Sibundong River, which eventually

flows to the Indian Ocean.

Its total river lengths to the proposed intake sites of Poring-1 and Poring-2 are about 20 km and 22 km,

respectively, with total height differences of 855 m and 1,093 m between the proposed intake sites and the

top of Mt. DK. Siborboron, which provides the longest stream length. Catchment areas at the proposed

intake sites of Poring-1 and Poring-2 are 87 km2 and 91 km2, respectively.

Source: JICA Survey Team

Figure 3.4.1 Watershed Area of Poring River

(2) Climate Conditions

The project site is located in a tropical rainforest climate (Af) area where the climate is characterized by

two vague rainy seasons from March to April and October to December as shown in Figure 3.4.2.

Photo taken by the JICA Survey Team

Poring River near the Proposed Intake Site

Poring River

Batutunggal River

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Although air temperatures vary by altitude, the mean monthly air temperature in Hutaraya, which is close

to the project site and located at similar altitude, is about 23.7 ºC, which is stable for the whole year.

Average Rain Days, Precipitation and Sunshine %

Average Temperatures

Note: The above graphs are based on the data over the last 20 years in Hutaraya, North Sumatra, Indonesia. Source: Chinci World Atlas, http://www.chinci.com/

Figure 3.4.2 Climate Patterns in Hutaraya near the Poring River Basin

Mean annual rainfall at each gauging station around the project site largely varies from area to area as

shown in Table 3.4.1 and Figure 3.4.3. Mean daily evaporation at surrounding stations, which is

computed by the Indonesian Agency for Meteorology (Badan Meteorologi, Klimatologi, dan Geofisika:

BMKG)2, is summarized in Table 3.4.2. These stations are shown in Figure 3.4.4 later.

Table 3.4.1 Mean Monthly and Annual Rainfall around the Poring River Basin

2 Badan Meteorologi, Klimatologi, dan Geofisika (Indonesian Agency for Meteorology)

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Temperatures (°C)

Maximum Temp.Minimum Temp.Mean Temp.

(Unit: mm)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 Tarutung 1954~2000 BMKG 167 185 146 275 132 66 85 87 143 167 225 199 1,878

2 Bandara Silangit 2008~2015 BMKG 199 140 204 249 247 92 104 175 190 242 280 282 1,920

3 Pinangsori 2002~2015 BMKG 333 300 361 353 289 198 311 428 404 524 607 464 4,588

4 Hutaraya 1954~1999 BMKG 174 171 228 243 141 98 106 118 166 216 255 245 2,160

5 Adian Koting 2002~2011 BMKG 240 238 270 265 214 158 135 181 270 310 353 277 2,911

6 Hobuan 2005~2014 BWS S‐II*1 238 228 291 249 213 130 134 303 237 426 487 316 3,252

7 Sarulla 2001~2014 BWS S‐II*1 366 347 422 485 265 187 156 402 331 525 562 492 4,540

8 Sibolga 2002~2014 BWS S‐II*1 231 314 320 364 276 143 230 371 306 382 512 368 3,816

Note: *1 Balai  Wilayah Sungai  Sumatera II (Regional  Office of the Ministry of Public Works)

Annual

Mean

Mean Monthly RainfallNo. Station Name

Data

PeriodSource

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Source: BMKG, BWS S‐II 

Figure 3.4.3 Mean Monthly Rainfall around the Poring River Basin

Table 3.4.2 Mean Daily Evaporation around the Poring River Basin

(3) Target Survey

In this survey, the project is designed to take river water only at Poring-1 Intake. The Poring-2 Mini

Hydropower plans to directly utilize the power discharge of Poring-1, as described in Chapter 4. This

means that the stream flow of the Poring River is diverted at Poring-1 Intake site only. Therefore, the low

flow analysis focuses on the estimation of continuous long-term stream flow at Poring-1 Intake site. As

for flood analysis, since the flood peak discharge is necessary to determine the height of structures for

Poring-1 and Poring-2, therefore, the flood peak discharge is estimated for both sites.

3.4.2 AVAILABLE HYDROLOGICAL DATA

(1) Collection of Existing Hydrological Data

The availability of collected daily hydrological data is summarized in Table 3.4.3. Besides, monthly

rainfall data was collected from the pre-FS review report3 as shown in Table 3.4.4. The locations of

respective stations are shown in Figure 3.4.4. As seen in the tables below, many of the stations have had

interruption of observations over a long period.

3 Review of Hydrology Analysis in the Pre-Feasibility Study Reports for Mini Hydro Power Projects in North Sumatra, Indonesia, January 2014, Nippon Koei Co., Ltd.

0

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400

500

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700

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Mean

 Monthly Rainfall 

(mm/m

onth)

Sarulla

Sibolga

Hobuan

Adian Koting

Hutaraya

Tarutung

Pinangsori

Bandara Silangit

(Unit: mm/day)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 Tarutung 2005~2014 BMKG 2.39 2.12 2.21 2.09 2.47 2.35 2.25 2.24 2.18 2.00 1.77 3.04 2.26

2 Sibolga 2005~2014 BMKG 5.27 4.35 5.03 5.55 4.89 4.60 4.70 4.48 4.90 4.12 4.44 4.44 4.73

Source: BMKG

No.Station

Name

Data

PeriodSource

Mean Daily Evaporation Annual

Mean

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Table 3.4.3 Availability of Daily Rainfall and Daily Discharge / Water Level Data

Table 3.4.4 Availability of Monthly Rainfall Data

Unfortunately, there is no existing rainfall gauging station in the Poring River basin. The JICA Survey

Team collected daily rainfall data observed at the rainfall gauging stations near the Poring River basin

from BMKG and the Regional Office of the Ministry of Public Works (Balai Wilayah Sungai: BWS)

Sumatera II4. However, since the observation system as well as data management of BWS is poor, daily

rainfall data in the northern side of the project area is not available for this study.

Furthermore, the Poring River had no water level gauging station before the commencement of this

preparatory survey. For this reason, the Kolang River basin, one of the neighboring basins around the

project site, is selected as an alternative basin for estimating long-term discharge at the project site. The

following subsections will therefore focus on the Kolang River basin as well. The detailed process of

selecting the Kolang River basin is described in Clause 3.4.5 (2) later.

4 Regional Office of the Ministry of Public Works, Indonesia, for river basin management in the Sumatra II Region

YearMonth

Station NameRainfall

PinangsoriBandara SilangitSarullaSibolgaHura BalangHobuanPengkolanPoring Bridge

Source: BMKG (for Pinangsori and Bandara Silangit), JDG (for Poring Bridge), BWS Sumatera II (for the others)Legend: Month Availability : Complete Data : Incomplete Data : No Data9 10 11 121 2 3 4 5 6 7 8

2013 20142007 2008 2009 2010 2011 20122001 2002 2003 2004 2005 2006

YearMonth

Station NameDischarge

Pasar SirongitDolok SanggleMaradeKolangHapesong Baru

Water LevelKolang

Source: BWS Sumatera IILegend: Month Availability : Complete Data : Incomplete Data : No Data

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

1 2 3 4 5 6 7 8 9 10 11 12

Year

Station NameSegala *1Batang Toru *1Aek Pahu *1Tarutung *1Hutaraya *1Barus *1 *2Siborong-borong *1Dolok Sanggul *1Gugur Balige *1Adian Koting *3

Legend: : Complete Monthly Data : Incomplete Monthly Data : No DataNote: *1: (Monthly data) Hydroinventory and prefeasibility studies, Nippon Koei Co. Ltd., 1999

*2: (Monthly data) Project for the Master Plan Study of Hydropower Development in Indonesia, Nippon Koei Co. Ltd., 2011*3: (10-day data) Pargaringan Pre-FS, PT. Jaya Dinamika Geohidroenergi, 2012. Reliability of data is questionable.

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Source: JICA Survey Team

Figure 3.4.4 Gauging Stations around the Poring River Basin

(2) Confirmation of Rainfall Observation System

In order to confirm that the rainfall data was obtained through appropriate manner of measurement, the JICA

Survey Team visited rainfall gauging stations and interviewed the gauge keepers for their measuring method.

The JICA Survey Team was able to contact the gauge keepers of the following stations:

- Pinangsori (BMKG)

- Bandra Silangit (BMKG)

- Hutabalang (BWS)

- Sibolga (BWS)

- Sarulla (BWS)

According to the result of the hearing, it was confirmed that all the stations use proper measuring instruments

such as rainfall collector and measuring cylinder. However, it was found that some of the rainfall gauging

stations run by BWS do not measure the rainfall at the designated time. Besides, tall trees are planted close to

the rainfall collector and some leaves cover it, especially in Sarulla and Sibolga. Therefore, data observed at

such stations are considered not reliable.

(3) Observation of Hydrological Data by the Survey Team

In order to know the hydrological relationship between the Poring River basin and the neighboring basins,

the following hydrological monitoring has been conducted in and around the Poring River basin. For the

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Preparatory Survey on North Sumatra Mini 3-12 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Poring River basin, the water level is monitored at the bridge located 1.1 km downstream from the

proposed Poring-1 Powerhouse site, and a rainfall collector is placed and monitored at a flat area close to

the bridge. Since the watershed of the Pargaringan River is quite similar to the Poring River in terms of

geological and topographical features, it is expected that their hydrological behaviors are alike. The water

level of the Pargaringan River is also monitored at the bridge over the Pargaringan River located 2 km

southward from the Poring Bridge.

Source: JICA Survey Team

Figure 3.4.5 Water Level Monitoring Stations at Kolang, Poring Bridge, and

Pargaringan Bridge

Table 3.4.5 Observation of Hydrological Data by the JICA Survey Team No. Data Item Interval Period Location Method

1 Rainfall Daily 15 June – 30 November 2014 Pargaringan Bridge *1 Manual

2 Hourly 5 Dec. 2014 – 11 Sept. 2015 Poring Bridge *2 Automatic

3 Water Level Daily (twice/day) 17 June – 30 November 2014 Pargaringan Bridge *1 Manual

4 Hourly 9 Dec. 2014–12 May 2015 *3 Poring Bridge *2 Automatic

5 Daily (twice/day) 25 April – 18 Sept. 2015 Poring Bridge *2 Manual

6 Pargaringan Bridge *1 Manual

7 Discharge Biweekly 16 May– 19 Sept. 2015 Poring Bridge *2 Using a current meter

8 Pargaringan Bridge *1 Note: *1 The Pargaringan Bridge is located along the Pargaringan River, an adjacent river to the Poring River. (CA = 76.5 km2)

*2 The Poring Bridge is 1.1 km downstream of the Poring-2 Intake site. (CA = 91.5 km2) *3 The gauge sensor had a serious malfunction since 13 May 2015. *4 The gauge sensor had a serious malfunction since 11 September 2015.

Source: JICA Survey Team

3.4.3 RAINFALL DATA

(1) Daily Rainfall of the Respective Rainfall Gauging Stations

The locations of rainfall gauging stations around the Poring River basin are shown in Figure 3.4.4 above.

The double mass curves (DMC) were prepared by using available raw data only as shown in Figure 3.4.6

to see the relationship of the monthly rainfall between each of the two gauging stations. Although DMC is

usually prepared by using annual rainfall data, this report presents DMCs of monthly data because annual

data is not calculable in many years due to a lot of missing data. The DMCs revealed that there are some

significant deviations among the data of the rainfall gauging stations in Sallura and it may be caused by

Kolang

Pargaringan Br.

Poring-1 Poring-2 Poring Br. Poring River

Pargaringan River

Kolang River

Final Report

Preparatory Survey on North Sumatra Mini 3-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

the inappropriate manner of measurement as aforementioned. For DMCs of Pengkolan and Hobuan, there

are some deviations observed around some extreme torrential rainfall events of more than 1,000

mm/month such as in October-November 2008.

Source: JICA Survey Team

Figure 3.4.6 Double Mass Curve for Each of the Rainfall Gauging Station

For estimation of long-term basin mean rainfall between 2005 and 2014, missing daily rainfall data is

filled by applying linear regression lines. The linear regression lines are used to generate the data

according to the level of correlation, i.e., the missing data is synthesized from the highest correlated data.

However, as some of the rainfall monitoring stations run by BWS do not correctly measure the rainfall,

the priority of such data is arbitrarily lowered. Besides the data where the correlation coefficient to the

target station is less than 0.4 is not considered for synthesizing the missin data. The regression equation

lines as well as correlation coefficients between each rainfall station are presented in Table 3.4.6.

Bandara Silangit Poring Bridge

Pin

an

g S

ori

Sa

rulla

Sib

olg

a

Pinang Sori Sarulla Sibolga Hura Balang Kolang / Hobuan Pengkolan

Hu

ra B

ala

ng

Ko

lan

g /

Ho

bu

an

Pe

ng

kola

nB

an

da

ra S

ilan

git

Po

rin

g B

rid

ge

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(1,000mm0

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(1,000mm)

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(1,000mm)

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(1,000mm

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(1,000mm)

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(1,000mm

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(1,000mm)

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(1,000mm)

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R5  (1,000mm

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R5  (1,000mm

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R5  (1,000mm

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R5  (1,000mm

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(1,000mm)

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(1,000mm

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(1,000mm)

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(1,000m

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(1,000m

R7

(1,000mm

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(1,000mm)

R7

(1,000mm

0

1

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0 1 2 3

R2

(1,000mm)

R7

(1,000mm

0

1

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3

4

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0 2 4 6

R1

(1,000mm)

R7  

(1,000mm

0

1

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2

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0 1 2 3

R3

(1,000mm)

R7

(1,000mm)

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0 2 4 6

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(1,000mm)

R7

(1,000mm

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(1,000m

R7

(1,000mm

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(1,000mm)

R7

(1,000mm

DataNot Available

DataNot Available

Final Report

Preparatory Survey on North Sumatra Mini 3-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 3.4.6 Equation of Regression Line and Correlation Coefficient

Source: JICA Survey Team

(2) Basin Mean Rainfall

The basin mean rainfall for the Poring Intake site and Kolang Water Level Gauging Station is obtained by

Thiessen method. Thiessen’s polygons made over the Poring and Kolang River basins are shown in

Figure 3.4.7. As the number of rainfall stations near the Poring River basin is limited, the basin rainfall

for the Poring Intake site is only covered by the data at the Poring Bridge. For the Kolang River basin, the

basin rainfall is calculated by the data of Hobuan (Thiessen’s coefficient: 18.0%), Poring Bridge (80.1%),

and Pinangsori (1.9%) stations.

Base Station Coefficient of Observation

No. Target Station Priority No. Station Name Correlation Condition Station y = a * ( Station x )

(y) (x) (x) ( R2) (z)

1 Pinangsori 1 Poring Bridge 0.600 Good Pinangsori = 0.811 * ( Poring Bridge )

2 Huta Balang 0.795 Fair Pinangsori = 1.043 * ( Huta Balang )

3 Bandara Silangit 0.455 Good Pinangsori = 1.583 * ( Bandara Silangit )

2 Sarulla 1 Poring Bridge 0.872 Good Sarulla = 0.724 * ( Poring Bridge )

2 Bandara Silangit 0.453 Good Sarulla = 1.546 * ( Bandara Silangit )

3 Pengkolan 0.584 Fair Sarulla = 1.306 * ( Pengkolan )

3 Sibolga 1 Poring Bridge 0.836 Good Sibolga = 0.990 * ( Poring Bridge )

2 Pinangsori 0.533 Good Sibolga = 0.793 * ( Pinangsori )

3 Huta Balang 0.619 Fair Sibolga = 0.870 * ( Huta Balang )

4 Huta Balang 1 Pinangsori 0.795 Good Huta Balang = 0.894 * ( Pinangsori )

2 Poring Bridge 0.617 Good Huta Balang = 0.878 * ( Poring Bridge )

3 Sibolga 0.619 Fair Huta Balang = 1.000 * ( Sibolga )

4 Bandara Silangit 0.421 Good Huta Balang = 1.498 * ( Bandara Silangit )

5 Hobuan 1 Bandara Silangit 0.602 Good Hobuan = 2.309 * ( Bandara Silangit )

2 Pengkolan 0.701 Fair Hobuan = 1.441 * ( Pengkolan )

3 Pinangsori 0.404 Good Hobuan = 0.708 * ( Pinangsori )6 Pengkolan 1 Poring Bridge 0.592 Good Pengkolan = 0.575 * ( Poring Bridge )

2 Pinangsori 0.510 Good Pengkolan = 0.615 * ( Pinangsori )3 Bandara Silangit 0.506 Good Pengkolan = 1.345 * ( Bandara Silangit )4 Hobuan 0.701 Fair Pengkolan = 0.576 * ( Hobuan )

7 Bandara Silangit 1 Poring Bridge 0.783 Good Bandara Silangit = 0.437 * ( Poring Bridge )2 Pinangsori 0.455 Good Bandara Silangit = 0.501 * ( Pinangsori )3 Hobuan 0.602 Fair Bandara Silangit = 0.311 * ( Hobuan )

8 Poring Bridge 1 Bandara Silangit 0.783 Good Poring Bridge = 2.038 * ( Bandara Silangit )2 Pinangsori 0.600 Good Poring Bridge = 1.077 * ( Pinangsori )3 Sibolga 0.836 Fair Poring Bridge = 0.938 * ( Sibolga )4 Huta Balang 0.617 Fair Poring Bridge = 0.987 * ( Huta Balang )5 Pengkolan 0.592 Fair Poring Bridge = 1.466 * ( Pengkolan )

Regression Equation Line : y = ax

Final Report

Preparatory Survey on North Sumatra Mini 3-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 3.4.7 Thiessen Polygon for Poring-1 Intake Site and Kolang Water Level Observatory

The calculated basin mean rainfall for Poring-1 Intake site and the Kolang water level gauging stations

are shown in Table 3.4.7, Figure 3.4.8, Table 3.4.8, and Figure 3.4.9. As shown in the figure and table,

ten-year average of annual basin mean rainfall of Poring-1 Intake site and Kolang stations are 4,889

mm/year and 4,714 mm/year, respectively. The basin rainfall for the Kolang stations by BMKG’s isohyet

map is calculated at 3,448 mm/year, therefore, the calculated basin mean rainfall by Thiessen method is

higher by around 1,000 mm/year than that is estimated by BMKG’s isohyet map. The annual rainfall at

Pinangsori rainfall gauging station, which is located close to the project site, recorded 4,588 mm/year

from 2002 to 2015, and therefore, the basin rainfall given by Thiessen method is not far deviated from the

actual record.

Table 3.4.7 Estimated Basin Rainfall at Poring-1 Intake Site

Source: JICA Survey Team

(unit: mm)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total2005 236 206 296 186 100 189 374 789 335 1,038 603 485 4,8382006 418 523 392 519 206 200 245 383 606 735 522 597 5,3472007 444 420 367 260 301 226 684 243 552 1,018 688 378 5,5812008 321 337 110 183 304 204 311 603 323 476 590 473 4,2342009 300 321 726 121 224 87 202 227 567 438 501 338 4,0522010 626 460 738 381 445 457 391 434 525 383 830 356 6,0272011 325 351 450 529 222 158 249 444 348 671 887 1,032 5,6652012 121 418 348 484 211 209 491 388 274 335 708 735 4,7222013 389 677 234 404 333 121 145 348 301 362 269 817 4,4002014 218 98 137 538 503 269 179 418 191 378 803 294 4,0242015 502 408 434 671 218 286 287 279 454 ‐ ‐ ‐ ‐

Minimum 121 98 110 121 100 87 145 227 191 335 269 294 4,024Maximum 626 677 738 671 503 457 684 789 606 1,038 887 1,032 6,027Average 355 383 385 389 279 219 323 414 407 583 640 550 4,889

Note: "-" denotes no data

Poring-1 Intake Catchment

Kolang Catchment Hobuan

Poring Br.

Pinangsori

Final Report

Preparatory Survey on North Sumatra Mini 3-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 3.4.8 Monthly and Annual Basin Mean Rainfall of Poring-1 Intake Site

Table 3.4.8 Estimated Basin Rainfall at the Kolang Water Level Gauging Station

Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.4.9 Monthly and Annual Basin Rainfall at the Kolang Water Level Gauging Station

3.4.4 RUNOFF DATA

(1) Daily Discharge Data

Initially, the runoff data around the Poring River basin were collected from BWS Sumatera II in the form

of discharge data as summarized in Table 3.4.9. The specific discharges per catchment area of 100 km2

range from 2.6 to 8.2 m3/s/100 km2 except Sipansihaporas. According to the collected data, runoffs for

Dolok Sanggle and Marade are relatively high considering the isohyetal lines between 1,500 and 2,500

mm/year as shown in Figure 3.4.4.

0 

100 

200 

300 

400 

500 

600 

700 

Jan

Feb

Mar

Apr

May Jun

Jul

Aug

Sep Oct

Nov

Dec

Average

 Monthly Rainfall 

(mm/m

onth)

Year: 2005‐2015  (Sep.)

0 

1,000 

2,000 

3,000 

4,000 

5,000 

6,000 

7,000 

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

Maxim

um Monthly Rainfall 

(mm/year)

Average: 4,889 mm/year

Year: 2005‐2015  (Sep.)

(unit: mm)

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total2005 226 204 305 191 128 195 349 746 313 929 604 441 4,6322006 386 501 388 496 201 190 250 367 570 685 486 556 5,0762007 420 381 354 248 285 221 590 219 486 909 624 352 5,0902008 311 310 178 220 285 193 321 585 343 579 695 488 4,5082009 282 329 627 144 224 127 194 276 513 387 469 312 3,8832010 564 437 666 372 451 395 346 395 482 442 776 329 5,6552011 322 355 427 492 236 175 230 458 339 614 812 941 5,4012012 113 392 326 453 198 196 461 385 247 317 663 688 4,4402013 357 598 214 384 317 142 135 336 271 328 353 782 4,2162014 210 85 132 537 535 271 168 496 229 411 830 333 4,2372015 513 339 431 643 261 261 280 282 469 ‐ ‐ ‐ ‐

Minimum 113 85 132 144 128 127 135 219 229 317 353 312 3,883Maximum 564 598 666 643 535 395 590 746 570 929 830 941 5,655Average 337 357 368 380 284 215 302 413 388 560 631 522 4,714

Note: "-" denotes no data

0 

100 

200 

300 

400 

500 

600 

700 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Average

 Monthly Rainfall 

(mm/m

onth)

Year: 2005‐2015  (Sep.)

0 

1,000 

2,000 

3,000 

4,000 

5,000 

6,000 

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

Maxim

um Monthly Rainfall 

(mm/year)

Average: 4,714 mm/year

Year: 2005‐2015  (Sep.)

Final Report

Preparatory Survey on North Sumatra Mini 3-17 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 3.4.9 Summary of Discharge Data around the Poring River Basin

Source: BWS Sumatera II

While, there is a hydropower project, namely: Sipansihaporas Hydroelectric Power Project near Sibolga.

The project was constructed with the assistance of Japanese official development assistance (ODA) loan,

and the site is located around 30 km toward the southeast from the Poring 1 and Poring 2 project sites.

The project is designed along the Sibuluan River flowing to the Indian Ocean. According to the feasibility

study on the Sipansihaporas project5, the specific discharge of the Sipansihaporas Hydroelectric Power

Project was calculated at 10.0 m3/s/100 km2 which is larger than any other neighboring basin. However,

according to a technical article6 published in 2008, the catchment area of the project is revised to 240 km2.

With this figure of 240 km2, the specific discharge of the Sipansihaporas project is calculated at 8.2

m3/s/100 km2 which is the same value as that of Kolang Water Level Gauging Station.

Figure 3.4.10 presents the comparison of duration curves of collected discharge data between the above

five stations except Sipansihaporas. Only the years 2009 and 2011 provide a series of complete data for

the stations. The graphs also express that the specific discharge of Marade is larger than the others.

However, the other gauging stations show similar trends of specific discharge and gradual decrease rate

particularly in the low flow part.

Source: BWS Sumatera II

Figure 3.4.10 Duration Curves of Collected Discharge Data

5 JICA, “Feasibility Study on Sipansihaporas Hydroelectric Power Development Project” July 1990, Japan. 6 Nishiguchi, et al, “Issues and Countermeasures for Construction of Sipansihaporas Hydroelectric Power Project in Indonesia ” 37th Symposium for Rock-Mechanics, Japan Society of Civil Engineering, January, 2008 (translated from Japanese)

Catchment Area Average  Discharge Speci fic Discharge Runoff

Year Months [ km2] [ m

3/s  ] [ m

3/s/100km

2 ] [ mm/year ]

Pasar Si rongi t Aek Sigeaon 1992~2013 178 350.6 12.7 3.6 1,142

Dolok Sanggle Aek Sibundong 2001~2013 149 50 2.6 5.2 1,629

Marade Aek Si lang 2000~2013 153 163.8 8.1 5.0 1,564

Kolang Aek Kolang 2005~2013 80 464.4 38.0 8.2 2,577

Hapesong Baru Aek Batang Toru 1992~2013 183 2773 73.3 2.6 834

Sipans ihaporas Aek Sibuluan 1978~1985 96 196 19.7 10.0 3,163

Avai labi l i tyStation Name River Name

0

5

10

15

20

25

30

35

40

45

50

0 30 60 90 120 150 180 210 240 270 300 330 360

Specific Discharge

 (m3/s/100km

2)

Day

Pasar Sirongit (350.6 km2)Dolok Sanggle (50 km2)Marade (163.8 km2)Kolang (464.4 km2)Hepsong Baru (2773 km2)

Year: 2009

0

5

10

15

20

25

30

35

40

45

50

0 30 60 90 120 150 180 210 240 270 300 330 360

Specific Discharge

 (m3/s/100km

2)

Day

Pasar Sirongit (350.6 km2)Dolok Sanggle (50 km2)Marade (163.8 km2)Kolang (464.4 km2)Hepsong Baru (2773 km2)

Year: 2011

Final Report

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(2) Water Level Records at Poring Bridge Water Level Observatory

The water level monitoring of the Poring River at the Poring Bridge has been conducted since December

2014, and the water level of the Pargaringan River has been monitored since July 2014. From May to

September 2015, the JICA Survey Team conducted discharge measurements at the Poring Bridge and

Pargaringan Bridge. The water level data until August 2015 was adopted in this hydrological analysis.

The result and discussion of the discharge measurement are described in Section 3.4.5 (5).

(3) Water Level Records at Kolang Water Level Observatory

The daily water level records at the Kolang Gauging Station were collected as shown in Figure 3.4.11

below. According to BWS Sumatera II, large-scale water utilization including irrigation scheme is neither

implemented nor planned in the Kolang watershed at present as is the case with the Poring watershed.

Source: BWS Sumatera II

Figure 3.4.11 Daily Water Level at the Kolang Water Level Gauging Station

Besides, although the water level data for 2014 are collected as expressed in the above graph, it was

found through the field reconnaissance that the 2014 data is unreliable because it was measured by means

of a movable gauge after the fixed gauge was flushed away by flood in early 2014. Thus, the water level

data for 2014 is not used in the following analysis. In June 2015, a new water level gauge was installed

and fixed to the foundation at Kolang Water Level Gauging Station.

3.4.5 LOW FLOW ANALYSIS

(1) General Approach

The continuous long-term runoff data for a time period of more than ten years at the proposed intake weir

site is normally required for evaluating an optimum development scale of the project through power

output computation. Further, it is highly expected that the runoff data should be of high accuracy because

measurement on economic viability of project is highly dependent on the reliability of available runoff

records. On the Poring-1 and Poring-2 MHPP, daily runoff data are required because the type of

hydropower development scheme is run-of-river type. However, as stated in Section 3.4.1 (3), river water

is taken only at the Poring-1 Intake Weir and the water is used for the power generation of both Poring-1

and Poring-2, therefore, the long-term low flow is estimated only at the proposed Poring-1 Intake site.

In the low flow analysis, water level of the Kolang River is measured at the Kolang Water Level Gauging

Station for the duration of 6.6 years, that is from 2005 to 2015 except 2008, 2013, and 2014. Out of the

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

05 06 07 08 09 10 11 12 13 14

Daily W

ater Level (m)

Year

no use in analysis due to inaccurate measurement

Final Report

Preparatory Survey on North Sumatra Mini 3-19 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

period of which the Kolang River discharge data is not available, the water level records measured at the

Poring Bridge and the Pargaringan Bridge are used. The period where is no stream flow record at Poring

Bridge and Pargaringan Bridge is not available, stream flow during such period is estimated by the

hydrological model which can simulate hydrologic behavior of rainfall to runoff of the Poring River at the

Poring Intake site. For simulation by the hydrological model, the input is the estimated basin rainfall as

described in Section 3.4.3, and daily runoff is estimated through the model.

The outline of low flow analysis is summarized in Figure 3.4.12.

As for the hydrological model, the Tank Model Method (Sugawara, 1956) was adopted for this low flow

analysis. Whereas, hydropower projects in Indonesia usually use i) FJ Mock, ii) National Rural Electric

Cooperative Association (NRECA), or iii) Tank Model, however, the said models i) and ii) are able to

assess only monthly discharge. Since this analysis requires estimating daily discharge, iii) Tank Model

was adopted.

Source: JICA Survey Team

Figure 3.4.12 Outline of Low Flow Analysis

(2) Selection of an Alternative River Basin

Since no stream flow measurement for the Poring River had been conducted until this preparatory survey,

it is necessary to select an alternative basin which is located close to the project area and has long-term

stream flow data available. The hydrological and geological features of the neighboring river basins were

compared as shown in Table 3.4.10. Although it is desirable to select a similar basin to the Poring River

basin from every point of view, the respective neighboring basins indicate both merits and demerits.

Collection of Existing Daily Runoff Records around Poring River

Selection of Alternative River Basin  (A) 

Conversion of Runoff Data from the Basin (A) into the Poring Basin

Reliability Check of Runoff Records at the Basin (A) 

Synthesizing Lacked Data

CorrelationAnalysis  of Alternative Basin  (A) and the Poring River

Test of Consistency of Rainfall  Records

CorrelationAnalysis  of Rainfall  Records

Estimation of Daily Rainfall

Collection of Rainfall  Data

Confirmation of Measurement Condition

Observation of Rainfall&Runoff  Data  in the Poring Basin

Development of Rainfall‐RunoffSimulation Model (Tank Model)

Estimation of Long‐term Runoff at the Poring Intake Sites

Synthesizing Data by Tank Model Simulation

Runoff Analysis Development of HydrologicalModel Rainfall Analysis

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Table 3.4.10 Comparison of Hydrological and Geological Features No. River Basin Catchment Area Isohyetal Line Runoff Data Availability*1 Major Geology*2 Remarks

1 Poring-1 87.5 km2

2,500~3,000 mm 2014 to date MPisl, Tmvo Study Area Poring-2 91.0 km2

2 Pasar Sirongit 350.6 km2 1,500~2,000 mm 1991~2013 Qvt, Tmvo

3 Dolok Sanggle 50 km2 1,500~2,500 mm 2001~2013 Qvt

4 Marade 163.8 km2 1,500~2,500 mm 2000~2013 Qvt

5 Kolang 464.4 km2 2,500~4,000 mm 2007~2013 MPisl, Tmba

6 Hapesong Baru 2,773 km2 1,500~4,000 mm 1992~2013 Qvt, Tmvo

7 Sipansihaporas 196.0 km2 3,500~4,000 mm Not obtainable Qvt, Tmba Existing HPP

Note: *1: Out of available years, only the first and last years are shown. *2: MPisl = Sibolga Granite Complex (granodiorites, granites and diorites), Tmvo = Toru Volcanic Formation (andesites, agglomerates, and breccias), Qvt = Toba Tuff (rhyodacitic ignimbrites), Tmba = Barus Formation (coarse to fine sandstones sometimes arkosic and/or micaceous, carbonaceous shales, and coals)

Source: BWS Sumatera II, BMKG, and Geological Research and Development Centre, Indonesia

Under these circumstances, the following river basins were excluded from the alternative subject area

with different reasons.

a) The catchment area of Pasar Sirongit has been already developed and therefore its land use situation is quite different from the Poring River basin. It will be necessary to consider the impact of water utilization to the discharge data. Actually, the average discharge is decreasing in recent years from 18.20 m3/s (1992~1998) to 11.03 m3/s (2006~2013).

b) The discharge data of Dolok Sanggle is not reliable because the same H-Q curve is used even after the gauging station was moved to 5 km downstream in the mid-2000s. Pre-FS review report also pointed out that its runoff coefficient is over 100%.

c) The Silang River that has the Marade Gauging Station flows into the Straits of Malacca side, although the Poring River flows to the Indian Ocean. Besides, since its watershed is located at high ground, the topographic condition is different from the Poring watershed.

d) Hapesong Baru has a too-large catchment area compared with the Poring catchment. Also, the watershed has various geological features due to its large area. This makes hydrological simulation complex and uncertain.

e) The discharge data of Sipansihaporas were not provided by PLN despite the repeated request by the JICA Survey Team.

The only remaining alternative is the Kolang River basin. Actually, its catchment area is almost five times

larger than the Poring-1 intake catchment, however the geological and topographical conditions are

similar to the Poring River as shown in Table 3.4.10. The Kolang River originates from the same

mountain range as the Poring River and flows into the Indian Ocean. Besides, the Kolang River basin has

not developed yet and therefore it is covered mostly by forest as is the case with the Poring River basin.

Therefore, the Kolang River basin was selected as an alternative basin.

1) Correlation of the Stream Flow between Poring Bridge and Kolang Stations

As described in Section 3.4.5 (3), a new water level gauge is installed and fixed to the foundation at

Kolang Water Level Gauging Station in July 2015.

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Figure 3.4.13 shows the scatter plot of concurrent

observed stream flow data at Poring Bridge and

Kolang Station from June 2015 to July 2015. It is

noted that the old rating curve that converts water

level to discharge, is tentatively used to estimate

the discharge of the Kolang River since the rating

curve for the new water level gauge has not been

updated yet. As shown in the figure, the data is

spotted close to the regression line. And the

correlation coefficient is calculated at 0.82, which

is high enough to say they are well correlated.

Accordingly, it is adequate to select the Kolang

River basin as the alternative basin for the Poring

River.

(3) Review of H-Q Curve (Water Level – Discharge Rating Curve)

Figure 3.4.14 (A) presents three kinds of H-Q curve as well as the plots of discharge data measured by

BWS Sumatera II (BWS) at the Kolang Gauging Station between 1986 and 2014. According to BWS, the

discharge data of Kolang is calculated by using these H-Q curves, which were developed by Puslitbang

SDA7. Since the trend of measured discharge largely changed from 1990 to 2000, and there are large gaps

in the water level record between the discharge measurement and water level monitoring record before

2010, it was determined that only 2010 data is used in this study. Accordingly, the H-Q curve is

constructed using discharge measurement data after 2010 as shown in Figure 3.4.14 (B).

7 Pusat Penelitian dan Pengembangan Sumber Daya Air (Center for Research and Development of Water Resources)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0.0 20.0 40.0 60.0

Poring Bridge

 Discharge

 (m3/s) 

Korang Discharge  (m3/s)

Source: JICA Survey Team

Figure 3.4.13 Scatter Plot of Stream Flow Measured at Poring Bridge and Kolang Observatories (June 2015 to July 2015)

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(A) Measured Discharge Data and H‐Q Curve of BWS Sumatera II (B) Revised H‐Q Curve 

Source: BWS Sumatera II, the JICA Survey Team

Figure 3.4.14 Discharge Data Measured by BWS Sumatera II and Revised H-Q Curve

By using the discharge measurement data since 2010, the following H-Q rating curve was obtained.

Q = 4.928 x (H + 2.139)2

where, Q: discharge (m3/s),

H: water level (m)

(4) Converting Discharge at Kolang Gauging Station to the Proposed Poring-1 Intake Site

The discharge of the Kolang Station is converted to the discharge at the proposed Poring-1 Intake site by

using the following formula.

Where, QPoring(y, m, d) : daily discharge at the proposed Poring-1 Intake site on day d, month m, and year

y (d/m/y) (m3/s)

QKolang(y, m, d) : daily discharge at Kolang Station on d/m/y (m3/s)

RainPoring(y, m) : monthly basin rainfall at the proposed Poring-1 Intake site on m/y (mm/month)

RainKolang(y,m) : monthly basin rainfall at Kolang Station on m/y (mm/month)

C.A.Poring : catchment area of the proposed Poring-1 Intake (km2)

C.A.Kolang : catchment area of the Kolang Station (km2)

As shown in the equation, the discharge at Kolang Station is converted by the ratio of basin mean rainfall

and ratio of catchment area. By using the above equation, 6.6-year data from 2005 to 2015 except the

missing period is estimated.

(5) Discharge Measurement of the Poring River at the Poring Bridge

1) Discharge Measurement at Poring Bridge and Pargaringan Bridge

After May 2015, discharge measurement was conducted 10 times at the Poring Bridge and the

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60

Water Level (m)

Discharge (m3/s)

1986/11/171992/8/301992/10/131992/10/171993/1/241993/6/291993/10/131993/12/51994/5/51994/5/291995/1/312002/4/162007/7/192008/10/142009/6/82010/6/192010/10/82011/3/262011/9/232013/5/52014/5/72014/10/72014/12/10HQ 2007HQ 2009‐11,13HQ 2012

Year

2007 Q= 99.7 (H‐ 0 ) 2.8

2008

2009 Q= 41.65 (H‐ 0.1 ) 1.375

2010 Q= 41.65 (H‐ 0.1 ) 1.375

2011 Q= 41.65 (H‐ 0.1 ) 1.375

2012 Q= 45.5 (H+ 0.02 ) 2.15

2013 Q= 41.65 (H‐ 0.1 ) 1.375

1990‐2011

1991‐2011

1990‐2008

no information

‐‐‐

H‐Q Curve

no water level  record

Base  Discharge

1986‐1996

1986‐1996

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0.0 20.0 40.0 60.0 80.0 100.0

Gau

ge Heigh

t (m

)

Discharge (m3/s)

H‐Q Rating Curve at Kolang WL .Gauge 

Station

H‐Q Curve

Observed Discharge 

(2010 ‐ 2014)

Kolang

Poring

Kolang

PoringKolangPoring AC

AC

myRain

myRaindmyQdmyQ

..

..

,

,,,,,

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Pargaringan Bridge, respectively. The Pargaringan Bridge is located along the Pargaringan River, an

adjacent river to the Poring River, and more accessible by car compared with the Poring Bridge. By using

the measurement results, H-Q rating curves are prepared as shown in Figure 3.4.15.

Poring Bridge (C.A.= 91.5 km2)  Pargaringan Bridge (C.A.= 76.5 km2) 

Source: JICA Survey Team

Figure 3.4.15 H-Q Rating Curves at Discharge Measurement Points

2) Observed Runoff Data

By using the above H-Q curves and daily water level records from June 2014 to September 2015, daily

discharge is computed as shown in Figure 3.4.16. Since water level records from June to November 2014

are available only at Pargaringan Bridge, the discharge at Pargaringan Bridge is converted to the planned

intake sites of Poring-1 and Poring-2 with the respective catchment area ratios. Thus, more than one year

continuous runoff data is obtained. The runoff coefficient of one year from September 2014 to August

2015 is estimated at 68.3% as shown in Table 3.4.11.

Table 3.4.11 Runoff Coefficient Estimated by Observed Data in 2014-2015 Rainfall at Poring Bridge (1-year: 1 September 2014 ~ 31 August 2015) 4,605 mm

Runoff at Poring Intake Sites (1-year: 1 September 2014 ~ 31 August 2015) 3,147 mm Runoff Coefficient 68.3%

Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.4.16 Daily Rainfall and Discharge at the Intake Sites

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

0 5 10 15 20

Gauge

 Height (m

)

Discharge (m3/s)

H‐Q Curve

Obs.Q

Q = 13.84* (H + 0.357 )^2

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

0 5 10 15 20

Gauge

 Height (m

)

Discharge (m3/s)

H‐Q Curve

Obs.Q

Q = 15.21 * (H ‐ 0.282 )^2

0

20

40

60

80

100

120

140

1600

10

20

30

40

50

60

70

80

Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Daily Rainfall (m

m/day)

Daily Average

 Discharge

 (m

3/s)

Rainfall

Poring Bridge

Discharge Measurement (Poring Bridge)

Converted from Pargaringan Data

Year: 2014 Year: 2015

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(6) Daily Stream Flow Simulation by Tank Model

For the period where the Kolang discharge data is not available, the stream flow at the proposed Poring-1

Intake site is directly estimated by hydrological model, and “Tank Model” was selected as the

hydrological model.

The parameter of the tank model is determined to minimize the square root of the sum of the square of the

difference between the calculated and observed discharge as shown in the following equation:

Min ∑ , , . , ,

Where, Qobs(y, m, d) : observed daily discharge at the Poring Bridge on d/m/y (m3/s)

Qcalc.(y, m, d) : calculated daily discharge of the Poring River at the Poring Bridge on d/m/y (m3/s)

N : number of data

For minimization of above equation, an optimization program is applied to search the Tank Model

parameters. There are several studies to apply the optimization program for determining Tank Model

parameter such as Tanakamaru 8 , and recently the tank model parameter is sought by applying

metaheuristic optimization techniques. In this survey, particle swarm optimization9,10 is used as a

metaheuristic optimization method and tank model parameters are determined so as to minimize the

deviation between observed and calculated expressed by the equation above.

The tank model parameter determined by the optimization program is shown in Figure 3.4.17. Figure

3.4.18 shows the hydrograph of simulated and observed discharge at the Poring Bridge. The duration

curve of the simulated and observed discharge at the Poring Bridge is shown in Figure 3.4.19.

8 H.Tanakamaru, “Parameter Estimation for the Tank Model using Global Optimization”, Journal of Agricultural Engineering No.178, pp103-112, 1995. 9 T. Tada, “Optimization of Runoff Model Parameter by PSO Algorithm”, Journal of Hydrology and Water Resources, Vol 20, No.5 September 2007. (Original article is written in Japanese.) 10 C.A.G.Santos et al. “Application of a Particle Swarm Optimization to the Tank Model”, Risk in Water Resources Management (Proceedings of Symposium H03 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 347, 2011).

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Source: JICA Survey Team

Figure 3.4.17 Tank Model Parameter for the Runoff at the Poring Bridge

Source: JICA Survey Team

Figure 3.4.18 Discharge Hydrograph of Simulated and Observed Discharge of the Poring River

at the Poring Bridge from 2014 to 2015

As seen in Figure 3.4.19, the simulation results of low flow discharge indicate relatively acceptable

correspondence with the observed discharges, and therefore, it is supposed to be accurate enough to

estimate low flow to be used for the design of hydropower facilities.

0.00 

20.00 

40.00 

60.00 

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100.00 

120.00 

140.00 

160.00 

180.00 0.00 

5.00 

10.00 

15.00 

20.00 

25.00 

30.00 

35.00 

40.00 

45.00 

50.00 

2014/Jul 2014/Aug 2014/Sep 2014/Oct 2014/Nov 2014/Dec 2015/Jan 2015/Feb 2015/Mar 2015/Apr 2015/May 2015/Jun 2015/Jul 2015/Aug

Rainfall (m

m)

Discharge

 (m3/s)

Year/Month

Rainfall

Observed

Calculated

h1, 3

h1,2 h1,1

h2, 2

h2,1

wl1

d1, 4

d1,3

d1,2

d1,1

d2,1

d2,2 wl2

wl4

wl3 d3,1

h3, 1

h4, 1 d4,1

Inf.1

Inf.2

Inf.3

Inf.4

Abbr. Tank Col‐1

Initial depth wl1 20

No. of lateral hole 3 3

Height of hole 1 h1,1 117.972

Size of hole 1 d1,1 0.214

Height of hole 2 h1,2 68.306

Size of hole 2 d1,2 0.075

Height of hole 3 h1,3 0.047

Size of hole 3 d1,3 0.000

Height of infil. Hole d1,4 1.920

Size of infil. hole Inf.1 0.524Initial depth wl2 30

No. of lateral hole 2 2

Height of hole 1 h2,1 20.000

Size of hole 1 d2,1 0.099

Height of hole 2 h2,2 0.012

Size of hole 2 d2,2 0.001

Size of infil. hole Inf.2 0.525

Initial depth wl3 50

No. of lateral hole 1 1

Height of hole 1 h3,1 5.000

Size of hole 1 d3,1 0.050

Size of infil. hole Inf.3 0.492

Initial depth wl4 500

No. of lateral hole 1 1

Height of hole 1 h4,1 0.162

Size of hole 1 d4,1 0.007

Size of infil. hole Inf.4 0.003

Top Tank

2nd Tank

3rd Tank

4th Tank

Parameter of Tank Model Parameter Identification Found by Optimization Model

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Source: JICA Survey Team

Figure 3.4.19 Comparison of Flow Duration Curve of the Simulated and Observed Stream

Flow Discharge of the Poring River at the Poring Bridge

(7) Compilation of the Result of Low Flow Analysis

As the result of the above low flow analysis, the continuous long-term daily flow of the Poring River at the

Poring-1 Intake site is estimated for approximately ten-year duration from January 2005 to August 2015. For

the preparation of the daily flow data, 79 months data is estimated from the Kolang River discharge data, five

months data is converted from the Pargaringan River, nine months duration is taken from the Poring River

stream flow monitoring result. The rest of 35 months duration data is estimated by the Tank Model. The

reference of the data for estimation of the daily flow at Poring-1 Intake site is shown in Table 3.4.12.

Table 3.4.12 Reference of the Poring-1 Intake Site Daily Flow

Source: JICA Survey Team

The monthly average of the estimated stream flow of the Poring River at the Poring Bridge is shown in Table

3.4.13, and flow duration curve is shown in Figure 3.4.20.

According to the result, the standard deviation of the annual average of the Poring River discharge at the

Poring Bridge is 0.87 m3/s, and this value corresponds to 11.5% of the average flow. Thus, the yearly

fluctuation of annual average is judged to be small.

0

5

10

15

20

25

30

35

40

45

50

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Discharge

 (m3/s)  [ Full Scale ]

Exceedance Probability  in Percent (%)

Comparison of Calculated Q and Obserbed Q  at Poring.

Calculated Daily Dsicharge

Observed Daily Dsicharge

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

2005 K K K K K K K K K K K K

2006 K K K K K K K K K K K T2007 K K K K K K K K K K K K2008 T T T T T T T T T T T T2009 K K K K K K K K K K K K2010 K K K K K K K K K K K K2011 K K K K K K K K K K K K2012 T T T K K K K K K K K T2013 T T T T T T T T T T T T2014 T T T T T T Parg. Parg. Parg. Parg. Parg. Po2015 Po Po Po Po Po Po Po Po

"K": Estimated from the Kolang River discharge"T": Estimated by tank model"Parg.": Measured record at the Pargaringan bridge"Po": Measured record at the Poring bridge

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Table 3.4.13 shows that the site has no distinct wet and dry season, and the difference of the monthly average

discharge of the wettest month (December) and the driest month (July) is around 3 m3/s and the minimum

monthly flow is over 4.4 m3/s as shown in the table.

Table 3.4.13 Monthly Average Discharge at the Poring-1 Intake Site

Source: JICA Survey Team

Figure 3.4.20 Flow Duration Curve at the Poring-1 Intake Site from January 2005 to

September 2015

3.4.6 FLOOD ANALYSIS

(1) General Approach

The data related to the flood discharge at the project site is extremely limited, and long-term hourly

rainfall records are not available in and around the project area. Therefore, the following methods were

applied to obtain a comprehensive solution for the flood discharges through comparison:

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average

2005 6.25 6.27 6.05 6.14 6.72 5.95 6.11 5.98 6.26 6.47 6.91 6.53 6.30

2006 6.87 6.18 7.25 6.22 6.17 6.14 7.13 8.25 8.44 8.37 8.32 12.11 7.622007 6.52 6.05 6.79 6.23 6.39 6.23 6.30 6.72 7.57 6.43 6.35 6.47 6.502008 8.41 10.05 6.23 5.38 5.00 5.86 5.24 8.16 7.15 8.79 9.70 10.41 7.532009 10.54 7.96 8.20 6.60 5.90 6.21 7.48 6.65 6.24 7.62 8.36 6.63 7.372010 7.46 8.90 7.82 8.78 8.09 6.06 6.13 5.92 6.40 7.52 6.89 6.36 7.192011 7.34 6.47 6.24 6.68 6.60 5.99 6.06 6.66 7.18 7.44 9.11 10.96 7.232012 10.42 9.75 9.63 6.65 6.13 6.20 6.52 7.38 8.98 9.43 16.73 11.80 9.142013 10.35 12.39 10.07 9.73 8.95 6.14 5.32 5.49 6.99 6.14 5.47 10.84 8.162014 7.93 5.50 4.40 6.98 8.06 7.37 5.18 6.13 6.38 6.33 12.87 8.76 7.162015 8.39 8.69 9.46 9.80 10.54 8.80 7.37 7.41 8.81

Average 8.23 8.02 7.47 7.20 7.14 6.45 6.26 6.80 7.16 7.45 9.07 9.09 7.53

Stand. Dev. 1.58 2.16 1.76 1.52 1.60 0.88 0.82 0.91 0.94 1.13 3.40 2.40 0.87Maximum 10.54 12.39 10.07 9.80 10.54 8.80 7.48 8.25 8.98 9.43 16.73 12.11 9.14Minimum 6.25 5.50 4.40 5.38 5.00 5.86 5.18 5.49 6.24 6.14 5.47 6.36 6.30

0

10

20

30

40

50

60

70

0% 20% 40% 60% 80% 100%

Discharge

 (m3/s)

Exceedance Probability  in Percent

Discharge

(m3/s )

Discharge  95‐day 25% 8.1

Discharge  185‐day 50% 6.7

Discharge  275‐day 75% 5.9

Discharge  292‐day 80% 5.7

Discharge  328‐day 90% 5.4

Discharge  355‐day 97% 4.5

Maximum 61.9

Minimum 3.3

Average 7.5

Standard Deviation 3.0

Duration

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Synthetic Unit Hydrograph Method of U.S. Soil Conservation Service (SCS)11

Rational Formula Method to estimate peak flood discharge

Checking using the Creager’s Curve

(2) Rainfall Analysis

1) Depth-Area-Duration (DAD) Analysis

1-a) Depth-Duration (DD) Analysis

Generally, heavy rainfall occurs intensively in a short duration and sporadically in a limited area.

Although it is desirable to take into account the actual rainfall patterns that occurred in the target area

in the past, enough hourly rainfall data is not available in and around the Poring River basin.

Therefore, the design rainfall curve is determined as a centralized type of hyetograph.

1-b) Depth-Area (DA) Analysis

Considering the abovementioned particularity of heavy rainfall occurrence, the average depth of

storm rainfall (basin mean rainfall) is likely to be smaller than the point depth of storm rainfall. To

estimate the basin mean rainfall from the point rainfall, the area reduction factor showing the ratio of

basin mean rainfall to point rainfall is introduced as expressed below.

Pb = fa x P0

where, Pb : Basin mean rainfall [mm] P0 : Point rainfall [mm] fa : Area reduction factor

The area reduction factor (fa) was decided according to the criteria. As shown in Figure 3.4.21, the

area reduction factor of both Poring-1 and Poring-2 was estimated at 0.96

11 Former name of Natural Resources Conservation Service (NRCS), U.S. Department of Agriculture

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Source: Department of the Army, United States Army Corps of Engineers, Engineer Manual “Flood – Runoff Analysis”

Figure 3.4.21 Area-Adjustment of Point Rainfall

2) Probable Point Rainfall

The Hobuan Rainfall Gauging Station is used for flood analysis because it provides the longest term of

annual maximum rainfall record and also it is the nearest station to the project area. The annual maximum

daily rainfall at Hobuan Station for 21 years in total between 1984 and 2014 are enumerated in Table

3.4.14.

Table 3.4.14 Annual Maximum Daily Rainfall at the Hobuan Gauging Station Year 1984 1985 1986 1987 1988 1989 1991 1992 1993 1994 1997

Date 26-Feb 19-Aug 1-Nov 1-May 5-Mar 11-Nov 27-Nov 6-May 22-Apr 24-Aug 23-Aug

Rainfall (mm/day) 130.9 77.0 180.5 97.5 94.0 59.4 97.5 94.2 90.0 70.2 40.0

Year 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 ---

Date 24-Aug 6-Sep 5-Nov 7-Nov 21-Jun 15-May 4-Nov 26-Aug 10-Dec 14-May ---

Rainfall (mm/day) 200.0 137.0 150.0 220.0 210.0 200.0 145.5 99.3 190.4 130.0 ---

Note: The data of the years 1990, 1995, 1996 and 1998 to 2004 were not obtainable.

Source: BWS Sumatera II

The frequency curves of maximum daily point rainfall at the Hobuan Rainfall Gauging Station is given in

Figure 3.4.22. Different distribution types of curves are plotted on a lognormal probability paper. Besides,

the probable maximum daily rainfalls estimated for the respective return periods with the respective

distribution types are summarized in Table 3.4.15.

≈96  

Poring1 : 87.4 km2 (33.75 mi2)  

Poring‐2 : 91.0 km2 (35.14 mi2)  

96.3 

96.0 

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Lognormal Probability Paper 

Legend: Exp  =  Exponential distribution Gumbel  = Gumbel distribution SqrtEt  =  SQRT‐wxponential type maximum 

distribution Gev  = Generalized extreme value distribution LP3Rs  =  Log Pearson type III distribution   

(real number space method) LogP3  =  Log Pearson type III distribution   

(logarithmic space method) Iwai  =  Iwai distribution  Note: The graph is created by the hydrological statistics program developed by Japan Institute of Country‐ology and Engineering.

Source: JICA Survey Team

Figure 3.4.22 Annual Maximum Daily Rainfall with Different Distribution Types

Table 3.4.15 Probable Maximum Daily Point Rainfall at Hobuan Distribution Type Exp Gumbel SqrtEt Gev LP3Rs LogP3 Iwai

SLSC (99%) 0.075 0.051 0.058 0.046 0.04 0.035 0.04 Return Period (yrs) Daily Point Rainfall (mm/day)

100 354.7 310.7 391.6 277.3 222.7 273.7 283.4 50 311.3 279.2 336.4 257.9 217.5 255.3 260.4 20 254.0 237.2 268.8 229.0 207.1 227.6 228.2 10 210.7 204.7 221.2 203.8 194.7 203.2 201.9 5 167.3 170.8 176.1 174.7 175.9 174.4 172.7 2 110.0 119.7 116.5 124.4 130.8 123.9 123.8

Note: The rainfall was computed by the hydrological statistics program developed by the Japan Institute of Country-ology and Engineering. Source: JICA Survey Team

As seen in the figure, appropriate plots for judging the compatibility of 100-year probable rainfall were

not obtained from the limited data of 21 years.

In general, the distribution types of Gumbel, SqrtEt, or Gev should be preferentially selected rather than

the others if their SLSC12 values are less than 0.04, which is a criterion value for the selection of

distribution type, because the said three types are based on the extremal theory, while the other types are

determined by specific regional characteristics13.

In this study, the SLSC values of Gumbel, SqrtEt, and Gev are 0.051, 0.058, and 0.046, respectively.

12 SLSC value is an index to estimate compatibility with observed data. It is obtained by indexing the difference of probable rainfalls between “when the observed data are aligned by a plotting position formula” and “when estimated by probability distributions”. The compatibility is better as a SLSC value is small. 13 Draft Handbook on Planning for Small and Mideun-sized Rivers (September 1999, Japan Institute of Country-ology and Engineering)

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Only the Log Pearson type III, logarithmic space method (LogP3) provides an acceptable SLSC value of

0.035, which is lower than 0.04. Furthermore, even compared with Gev, which is the second-best

distribution type in term of adaptability and reliability, the differences of daily point rainfall for each

return period between LogP3 and Gev are less than 2%, and also both distribution curves are quite similar

particularly in the range of high probable scales including 100-year and 200-year. Thus, LogP3 is adopted

as a distribution type for this study.

3) Probable Basin Mean Rainfall

Applying the design area reduction factor of 0.96, the probable basin mean one-day rainfall with various

return periods at the intake sites of Poring-1 and Poring-2 are estimated as follows:

Table 3.4.16 Probable Basin Mean Rainfall for the Poring River Basin Return Period [year] 2 5 10 20 50 100 200 400

Probable Daily Basin Rainfall [mm/day] 119 167 195 218 245 263 279 293

Source: JICA Survey Team

(3) Design Flood

1) SCS Unit Hydrograph

A flood hydrograph is required for the planning of intake weirs. The unit hydrograph method established

by the U.S. Soil Conservation Service (SCS), which has been employed for various water resource

development projects to date, was applied to estimate the flood hydrograph simply from the probable

rainfalls. Originally, the SCS suggested that this method is applied to the catchment area not exceeding 20

ml2 (= 51.8 km2). However, even the lower Poring River basin represents the characteristic of

mountainous river, and thus, there is no significant difference in catchment characteristics between upper

and lower catchments even if the entire catchment of about 90 km2 is devided into two parts. Therefore, it

was determined in this study that the SCS method is applied to the entire catchment collectively. The

standard dimensionless unit hydrograph given by the SCS synthetic method is shown in Figure 3.4.23

Source: US Soil Conservation Service

Figure 3.4.23 Standard Dimensionless Hydrograph by SCS

The calculation procedures to determine the SCS unit hydrograph are described below.

0.00.10.20.30.40.50.60.70.80.91.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Q/Q

p

T/Tp

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SCS Unit Hydrograph Poring-1 Poring-2 Qp = 0.208 * A * Q / tp (US Soil Conservation Service Unit Hydrograph)

Qp : Peak discharge [m3/sec] 9.1 9.5 [m3/sec/mm]A : Catchment area [km2] 87 91 [km2] Q : Total volume of the unit graph (= 1 mm) 1 1 [mm] tp : Time to peak [hours] 2.00 2.00 [hours]

Time to Peak tp = 2 * tc / 3 2.0 2.0 [hours]

1.73 1.73 [hours] Rainfall Duration

D = 0.133 * tc 1.0 1.0 [hours] 0.35 0.35 [hours]

Flood Concentration Time tc = 3.97 * L0.77 * S-0.385 (Kirpich's formula) 2.6 2.6 [hours]

tc : Flood concentration time [min] 156 157 [min] L : Maximum length of travel of water [km] 19.7 22.2 [km] S : Average slope (= H/L) 0.028 0.035 H : Difference in elevation between the remote point in the basin and the outlet 550 788 [m]

The SCS unit hydrograph is derived based on the flood concentration time and mean rainfall in the unit

basin. The unit hydrograph is constructed for a unit rainfall of 1.0 mm. The peak discharge of the unit

hydrograph is calculated as follows:

pp t

QAQ 208.0

where, Qp : Peak discharge [m3/sec]

A : Catchment area [km2]

Q : Total volume of the unit graph (= 1 mm)

tp : Time to peak [hours]

The relationship of the time to peak (tp), and rainfall duration (D) with the time to concentration (tc) is

given below.

32 c

p

tt

0.133

Flood Concentration Time

Flood concentration time is defined as the traveling time from the most remote point in the catchment to

the forecast point, is given by the following formula.

385.077.097.3 SLtc (Kirpich's formula)

where, tc : Flood concentration time [min]

L : Maximum length of travel of water [km]

S : Average slope (= H/L)

H : Difference in elevation between the remote point in the basin and the outlet

The calculation results for Poring-1 and Poring-2 are respectively as follows:

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Poring-1 Poring-2

tc = 156 minutes (= 2.6 hours), 157 minutes (= 2.6 hours)

Qp = 9.1 m3/sec/mm, 9.5 m3/sec/mm

tp = 2.0 hours, 2.0 hours

D = 1.0 hour, 1.0 hour

Design Hyetograph

As there are no hourly rainfall data available in/around the project site, the design rainfall pattern

hyetograph was assumed using the following formula:

[Mononobe's Formula] 3

2

24 24

24

t

Rrt

[mm/hr] (for 24 hours)

where, rt : Average rainfall intensity in flood duration [mm/hr]

R24 : Probable daily rainfall [mm/day]

t : Time of concentration of runoff [hour]

A type of rainfall intensity pattern, namely, central concentration pattern in 24 hours is assumed for the

hyetograph for the reasons set forth below.

i) In general, the central concentration pattern is stochastically highly-reproducible compared with the forwards or backwards concentration patterns.

ii) The average of 48 rainfall patterns created based on the recorded hourly rainfall data in other areas in Indonesia became a central concentration pattern in terms of results.

Base Flow

In order to estimate the direct flood runoff, the base flow should be separated from the hydrograph. Based

on the observed discharge of the Poring River from January 2015 to May 2015, the base flow in both of

the Poring-1 and Poring-2 River basins during rainy season was estimated at 9 m3/s.

Direct Runoff Coefficient

In order to estimate the flood hydrograph by mean of unit-graph, it is required to compute the excess

rainfall by separating effective rainfall from storm rainfall, which generally includes losses from

interception, depression, soil moisture change, evaporation, and transpiration. Based on the observed

discharge and rainfall of the Poring River from January 2015 to May 2015, the maximum direct runoff

coefficient is 0.5 among floods which have hourly rainfall intensity of more than 20 mm. In this study,

the direct runoff coefficient for the proposed intake sites was assumed at 0.625 from the empirical runoff

coefficients provided in the Japanese Investigation Manual. This value is the average of the runoff

coefficients for the appropriate topographic features for the project site, as shown in Table 3.4.17.

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Table 3.4.17 Runoff Coefficient Depending on the Catchment’s Feature Topography or River Runoff Coefficient f Adopted Features

Steep mountains 0.75~0.90 - Tertiary mountains or hills 0.70~0.80 - Gently undulating lands and forest 0.50~0.75 0.625 Flat cultivated fields 0.45~0.60 - Paddy field under irrigation 0.70~0.80 - Mountainous river 0.75~0.85 - Small river in flat land 0.45~0.75 - Large river in flat land 0.50~0.75 -

Source: Technical Criteria for River Works: Practical Guide for Investigation (Ministry of Land, Infrastructure, Transport and Tourism, Japan)

Design Flood Hydrographs

The design flood hydrographs were obtained using the SCS unit hydrograph. Figure 3.4.24 shows the

hydrographs for 20-year, 100-year, and 200-year probable floods as well as their hyetographs. The peak

discharge for each flood is summarized in Table 3.4.18.

Poring‐1  Poring‐2 Source: JICA Survey Team

Figure 3.4.24 Hydrograph for 20-year, 100-year, and 200-year Floods at the Intake Sites

Table 3.4.18 Peak Flood Discharge at the Proposed Intake Sites by SCS Method Return Period

Daily Point Rainfall

Area Reduction Factor

Daily Basin Rainfall R24

Direct Runoff

Coefficient

Base Flow (assumed)

Flood Peak Discharge

R24 Poring-1 Poring-2 Poring-1 Poring-2 Poring-1 Poring-2[Year] [mm] [%] [%] [mm] [mm] (assumed) [m3/sec] [m3/sec] [m3/sec]

2 123.9 96 96 119 119 0.625 9.0 320 330 5 174.4 96 96 167 167 0.625 9.0 440 460

10 203.2 96 96 195 195 0.625 9.0 510 540 20 227.6 96 96 218 218 0.625 9.0 570 600 50 255.3 96 96 245 245 0.625 9.0 640 670

100 273.7 96 96 263 263 0.625 9.0 680 710 Source: JICA Survey Team

2) Rational Formula

Flood peak discharges for 100-year return period at the intake sites of Poring-1 and Poring-2 are

estimated at 887 m3/s and 866 m3/s, respectively, by means of the rational formula method as shown in

Table 3.4.19 below. They are about 1.30 and 1.22 times as large as the 100-year flood discharge

estimated by SCS Method. The details are described below.

0

20

40

60

800

200

400

600

800

1,000

0 12 24 36 48 60 72

Effective Rainfall [m

m/hour]

Discharge

 [m3/sec]

Time [hours]

Rainfall: 200‐yrRainfall: 100‐yrRainfall: 20‐yrDischarge: 200‐yrDiischarge: 100‐yrDischarge: 20‐yr

0

20

40

60

800

200

400

600

800

1,000

0 12 24 36 48 60 72

Effective Rainfall [m

m/hour]

Discharge

 [m3/sec]

Time [hours]

Rainfall: 200‐yrRainfall: 100‐yrRainfall: 20‐yrDischarge: 200‐yrDischarge: 100‐yrDischarge: 20‐yr

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Table 3.4.19 Peak 100-year Discharge Estimated by Rational Formula Description Poring-1 Poring-2 Unit Remarks

Catchment Area at the Intake Site A 87.4 91.0 km2 Map 1:50,000

Runoff Coefficient f 0.625 0.625 --- Gently undulating lands and forest

Inflow Time from the Most Upstream Area T1 0.38 0.38 hr 1.18 km2 shown in Figure 3.4.26

Elevation at (U) shown in Figure 3.4.26 HU 1,175 1,175 El.m Map 1:50,000

Elevation at (D) shown in Figure 3.4.26 HD 625 387.5 El.m Map 1:50,000

Distance between (U) and (D) L 19,744 22,189 m Map 1:50,000

Slope of River: I = (HU-HD) / L I 0.0279 0.0355 --- = 1 / 37, 1 / 29

Flood Propagation Velocity W 3.5 3.5 m/s I = 1/100 or more

River Flow Time: T = (1/3,600) x (L/W) T2 1.57 1.76 hr Kraven’s formula

Flood Concentration Time: T = T1 + T2 T 1.95 2.14 hr ---

Daily Basin Rainfall R24 263 263 mm/day 100-yr rainfall

Average Rainfall Intensity: RT = (R24/24) x (24/T)2/3 RT 58.4 54.8 mm/hr Mononobe's formula

Peak Runoff Discharge: Qp = (1/3.6) x f x RT x A Qp 887 866 m3/s Rational formula

Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.4.25 Topographical Measurement Points for Rational Formula Method

Rational Formula

[Rational Formula] ARfQ Tp 6.3

1 [m3/s]

where, Qp : Peak runoff discharge [m3/s]

f : Runoff coefficient

RT : Rainfall intensity of time duration [mm/hour]

A : Catchment area [km2]

Runoff Coefficient

The runoff coefficient was set as 0.625 for the same reason as the case of SCS unit hydrograph method as

mentioned above.

Flood Concentration Time

The flood concentration time was estimated as the total values of i) necessary inflow time to the most

upstream point of river and ii) necessary flowing time from the most upstream (U/S) point to the most

HU

HD‐1HD‐2

Poring‐1 Intake

Poring‐2 Intake

Most upstream area of 1.18 km2

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downstream (D/S) point of river, which is the intake site in this case.

i) Necessary inflow time to the most upstream point of river In general, in the case of mountainous area, 30 minutes (0.5 hrs) are required for flowing into the most upstream point of river from its catchment area of 2 km2. In the Poring River basin, the time is 0.38 hours computed by multiplying 0.5 hours by a square root of the catchment area ratio (1.18/2.0).

ii) Necessary flowing time from the most U/S point to the most D/S point of the river The flowing time is estimated by Kraven’s formula

[Kraven’s Formula] W

LT

600,3

1 [hr]

I >1/100 1/100 - 1/200 <1/200

W 3.5 m/s 3.0 m/s 2.1 m/s

where, T : Total concentration time [hour]

L : Length of river [m]

W : Flood velocity [m/sec]

I : River slope

Rainfall Intensity

The rainfall intensity was estimated by using a common method of Mononobe’s Formula.

[Mononobe’s Formula] 3

2

24 24

24

T

RRT

[mm/hour]

where, RT : Rainfall intensity of time duration [mm/hour]

R24 : Daily rainfall [mm/day]

T : Total concentration time [hour]

3) Comparison of Design Flood by Various Methods

The peak flood discharges estimated by the SCS unit hydrograph method and the Rational Formula are

summarized in Table 3.4.20 for comparison. There are no definite reasons to justify the design flood

because of the limited availability of the flood records and hourly rainfall. However, the discharges

estimated by the SCS method almost fall within the acceptable range of Creager’s Curve, while each of

Rational Formula is considerably out of the range. It is therefore judged that the SCS method could be

applied for the study. The details of Creager’s Curve are described in the following clause.

Table 3.4.20 Comparison of Peak Flood Discharges

Return Period

Daily Basin Rainfall (LogP3 Distribution)

Flood Peak Discharge SCS Method Rational Formula Creager’s Curve

Poring-1 Poring-2 Poring-1 Poring-2 Poring-1 Poring-2 Poring-1 Poring-2 [year] [mm/day] [mm/day] [m3/sec] [m3/sec] [m3/sec] [m3/sec] [m3/sec] [m3/sec]

2 119 119 320 330 401 392 --- --- 5 167 167 440 460 563 550 --- ---

10 195 195 510 540 657 642 --- --- 20 218 218 570 600 735 718 186~371 190~381 50 245 245 640 670 826 807 --- ---

100 263 263 680 710 887 866 371~557 381~571 Source: JICA Survey Team

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(4) Creager's Curve

The peak discharges of 20-year, 100-year, and 200-year probable floods were examined by plotting them

on the Creager’s Curve, which provides a comprehensive range of the regional characteristics of floods,

together with the discharges of other schemes in Sumatra Island as shown in Figures 3.4.26 to 28.

Flood peak discharges for the return periods of 20-year, 100-year, and 200-year in Sumatra Island are

supposed to be plotted on the Creager’s Curve with C = 10~20, 20~30, and 20~4014, respectively. The

Creager’s curve is computed by the following equations:

[Creager’s Curve] ap ACQ )3861.0()02832.046(

048.0)3861.0(894.0 Aa

where, Qp : Peak discharge of probable flood [m3/sec]

A : Catchment area [km2]

C : Creager's coefficient

Although the Creager’s Curve may provide only a rough indication, Figures 3.4.26 to 28 below indicates

that the 20-year, 100-year, and 200-year flood discharges estimated by SCS Method at the proposed

intake sites are within reasonable ranges as compared with the other projects in the region.

Source: JICA Survey Team

Figure 3.4.26 Comparison with 20-year Floods under Various Schemes in Sumatra

14 Hydroinventory and prefeasibility studies, Nippon Koei Co. Ltd., 1999

570

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐1

Other Schemes (20‐yr)C= 20C= 10Poring‐1

C=10

C=20

600

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐2

Other Schemes (20‐yr)C= 20C= 10Poring‐2

C=10

C=20

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Source: JICA Survey Team

Figure 3.4.27 Comparison with 100-year Floods under Various Schemes in Sumatra

Source: JICA Survey Team

Figure 3.4.28 Comparison with 200-year Floods under Various Schemes in Sumatra

(5) Estimation of Probable Flood during Dry Season

The peak discharges of small-scale probable floods during the dry season from January to July are

estimated for the purpose of construction planning. The annual maximum daily rainfalls limited to the dry

season are enumerated in Table 3.4.21.

Table 3.4.21 Maximum Daily Rainfall during January-July at the Hobuan Gauging Station Year 1984 1987 1988 1991 1992 1993 1994 1997 2005 Date 26-Feb 1-May 5-Mar 13-Feb 6-May 22-Apr 12-Feb 17-May 2-Mar

Rainfall (mm/day) 130.9 97.5 94.0 60.4 94.2 90.0 51.2 40.0 118.0 Year 2006 2007 2008 2009 2010 2011 2012 2013 2014 Date 12-Mar 18-Feb 17-Mar 21-Jun 15-May 29-Mar 24-Jul 27-Feb 14-May

Rainfall (mm/day) 81.0 89.0 130.0 210.0 200.0 130.0 97.3 78.2 130.0 Note: The data of the years 1985, 1986, 1989, 1990, 1995, 1996 and 1998 to 2004 were not obtainable. Source: BWS Sumatera II

Although the SLSC values of all distribution types exceed 0.04, the LogP3 type provides the lowest value

of 0.042. The LogP3 type is therefore adopted as a distribution type for the dry season as well. The

probable maximum daily point rainfalls estimated with LogP3 are summarized in Table 3.4.22.

680

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐1

Other Schemes (100‐yr)C= 30C= 20Poring‐1

C=20

C=30

710

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐2

Other Schemes (100‐yr)C= 30C= 20Poring‐2

C=20

C=30

720

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐1

Other Schemes (200‐yr)C= 40C= 20Poring‐1

C=20

C=40

760

10 

100 

1,000 

10,000 

1  10  100  1,000  10,000 

Discharge (m

3/s)

Catchment Area (km2)

Poring‐2

Other Schemes (200‐yr)C= 40C= 20Poring‐2

C=20

C=40

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Table 3.4.22 Probable Maximum Daily Point Rainfall for the Dry Season in Hobuan Return Period (yrs) 400 200 150 100 80 50 30 20 10 5 3 2 Rainfall (mm/day) 277.8 258.5 250.3 238.5 232.0 218.0 202.2 189.4 166.2 140.9 119.9 100.5

Note: The rainfall was computed by the hydrological statistics program developed by the Japan Institute of Country-ology and Engineering. Source: JICA Survey Team

Basically, the flood discharges are estimated by the SCS unit hydrograph method in the same way as the

above design flood. However, a runoff coefficient for the dry season is determined with a different

viewpoint. A runoff coefficient in the dry season is usually considered lower than the rainy season

because unsaturated soil absorb rain water particularly at the beginning of rainfall event, and therefore,

runoff becomes small compared with the case of rainy season. In this study, a runoff coefficient is

estimated by using hourly rainfall and hourly discharge data observed from January to May 2014 as

shown in Figure 3.4.29. The maximum hourly discharge during this period at the intakes of Poring-1 and

Poring-2 are estimated at 48 m3/s and 50 m3/s, respectively.

Note: Hourly discharge data between February 9 and 23 is missing. Source: JICA Survey Team

Figure 3.4.29 Hourly Rainfall and Discharge in Poring in the Dry Season

Since this rainfall is point rainfall, in some cases, the rainfall pattern does not directly correspond to the

discharge fluctuation. According to the observations of several hydrograph curves that produce favorable

response to hourly rainfall exceeding 20 mm/hr, it was found that the maximum runoff coefficient is

almost 0.35. Figures 3.4.30 expresses the flood hydrographs that produce the largest and second-largest

runoff coefficients during the observation period.

0

10

20

30

40

50

60

70

80

90

1000

10

20

30

40

50

60

70

80

90

100

1‐Jan 15‐Jan 29‐Jan 12‐Feb 26‐Feb 12‐Mar 26‐Mar 9‐Apr 23‐Apr 7‐May

Hourly Rainfall (m

m/hr)

Hourly Discharge

 (m

3/s)

Rainfall Discharge: Intake‐1 Discharge: Intake‐2

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Source: JICA Survey Team

Figure 3.4.30 Dry Season’s Flood Hydrographs for the Maximum Runoff Coefficients

By using the runoff coefficients of 0.35, the peak discharges of small-scale floods are estimated in the

same manner with the above design floods as summarized in Table 3.4.23. The peak discharge of 2-year

probable flood is estimated at 150 m3/s for both Poring-1 and Poring-2. This is almost three times larger

than the maximum hourly discharge recorded during the latest dry season and therefore it is considered

reasonable and safe.

Table 3.4.23 Peak Flood Discharge at the Proposed Intake Sites in the Dry Season Return Period

Daily Point Rainfall

Area Reduction Factor

Daily Basin Rainfall R24

Direct Runoff

Coefficient

Base Flow (assumed)

Flood Peak Discharge

R24 Poring-1 Poring-2 Poring-1 Poring-2 Poring-1 Poring-2[Year] [mm] [%] [%] [mm] [mm] (assumed) [m3/sec] [m3/sec] [m3/sec]

2 100.5 96 96 96 96 0.35 6.0 150 150 5 140.9 96 96 135 135 0.35 6.0 200 210

10 166.2 96 96 160 160 0.35 6.0 240 250 20 189.4 96 96 182 182 0.35 6.0 270 280

Source: JICA Survey Team

0

10

20

30

40

50

600

10

20

30

40

50

60

15‐Apr 5:00

15‐Apr 7:00

15‐Apr 9:00

15‐Apr 11:00

15‐Apr 13:00

15‐Apr 15:00

15‐Apr 17:00

15‐Apr 19:00

15‐Apr 21:00

15‐Apr 23:00

16‐Apr 1:00

16‐Apr 3:00

Hourly Rainfall (m

m/hr)

Hourly Discharge

 (m

3/s)

Rainfall

Discharge: Intake‐1Discharge: Intake‐2

Runoff Coefficient = 0.332

0

10

20

30

40

50

600

10

20

30

40

50

60

7‐M

ay 5:00

7‐M

ay 7:00

7‐M

ay 9:00

7‐M

ay 11:00

7‐M

ay 13:00

7‐M

ay 15:00

7‐M

ay 17:00

7‐M

ay 19:00

7‐M

ay 21:00

7‐M

ay 23:00

8‐M

ay 1:00

8‐M

ay 3:00

Hourly Rainfall (m

m/hr)

Hourly Discharge

 (m

3/s)

Rainfall

Discharge: Intake‐1Discharge: Intake‐2

Runoff Coefficient = 0.352

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3.5 GEOLOGY

3.5.1 REGIONAL GEOLOGY

The geology of project site is classified as a part of the Sibolga Granite Complex. In early Permian, the

Sibolga Granite Complex intruded into the Kluet formation of Carboniferous to early Permian

meta-sediments. Outcrops of Kluet formation occur as roof pendants in the Sibolga Complex are strongly

hornfelsed.

In the late Oligocene, the earlier Palaeogene sediments were deformed and uplifted to produce an

extensive erosional unconformity. This area remained emergent until the early Miocene when a

widespread transgression occurred. In the present onshore area this resulted in the deposition of the

largely non-marine Barus formation which overstepped onto the geanticlines. Toba Tuff of the late

Pleistocene age covered the preformed valleys. Following the eruption of the Toba Tuffs, further

movements occurred. Although depressions may have existed along the faults prior to the Toba event, the

distribution of tuffs and the apparent lack of a thick ignimbrite sequence, suggest that these grabens

largely post-date this event.

Legend:

ALLUVIUM: coastal and fluviatile clays, silts, sands, and gravels, also fan deposits, landslips and in grabens some peat.

OLDER ALLUVIUM: sands, silts, and clays, minor gravels.

TOBA TUFF: rhyodacitic ignimbrites BARU FORMATION: coarse to fine sandstones sometimes arkosic and/or micaceous carbonaceous shales and coals.

KLUET FORMATION: metaarenites and argillites, often hornfelsed.

SIBOLGA GRANITE COMPLEX: granodiorites, granites and diorites

Source: Geological Map of the Padangsidempuan and Sibolga Quadrangles, Sumatra, Geological Survey Institute of Indonesia

Figure 3.5.1 Geological Map of North Sumatera

Puk

Tmba

Mpisl

Qvt

Qh Qp

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3.5.2 GEOLOGICAL INVESTIGATION

(1) Scope of Work

The geological investigation composed of core drilling

with in-situ tests and laboratory tests was carried out for

the purpose of obtaining subsurface geological data of the

structures such as intake weir, head tank, penstock, and

powerhouse sites. Investigation items and their purposes

are as mentioned below.

a) Ground Mapping (Proposed Structural Layout Area)

b) Core Drilling (11 holes, 150 m in total)

Standard Penetration Test (SPT) in Soil (9 holes, 88

nos. in total)

Permeability Test in Soil (5 holes, 7 nos. in total)

Lugeon Test in Rock (3 holes, 3 nos. in total)

c) Laboratory Test (3 holes, and boulders sampled from

riverbed)

Location of geological investigation and location of drill points are shown in Figure 3.5.2.

Note: B-3 was cancelled because of rapid river flow Source: JICA Survey Team

Figure 3.5.2 Location Map of Drilling Sites

Source: JICA Survey Team B-4 (Head Tank-1) Drilling

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(2) Results of the Investigations

The survey team received the summary of the drill-core observation with the results of in-situ tests, such

as Standard Penetration Test (SPT), Constant Head Test (CHT), and Lugeon Test.

3.5.3 GENERAL GEOLOGY AROUND THE PROPOSED STRUCTURE

The basement of the proposed structures in the project area, mainly consists of hard granite (the Sibolga

Granite Complex), locally of soft welded tuff (Toba Tuff). The geology of the project is composed of the

following:

(1) Granite (Gt)

The fresh part of base rock around the project site mainly consists of granite, which is coarse grained,

white to grey coloured, and very solid categorized in CH to CM rock grades. The preliminary joints

showing three directions are observed in 0.5-3 m unit, which are partly open and indicate high

permeability.

The thickness of weathered zone of granite increases up the slope, although fresh rock is observed around

the riverbed. From the middle to high elevation of slope, extremely weathered granite is discovered on the

surface outcrops, showing compacted sandy soil containing hard granite boulders of 1–3 m in diameter.

The layer of extremely weathered granite is assumed at 1-5 m thick in the lower slope, 15-20 m thick in

the higher slope. However, the thickness of extremely weathered layer may possibly become more than

20-30 m, locally around the landslide block and/or along the joint or fault.

(2) Tuff (Tf)

The tuff layer is distributed above the granite, especially on the ridge around the proposed Penstock-2 in

the west part of project area. The fresh part of tuff shows fine to medium grained, grey coloured, very

dense indicating 50+ of N-value, silty to sandy cores like a hardpan in drilling samples (Drill No.B-11).

Inside the project area, the tuff outcrops are not discovered with the exception of the tuff fragments on the

surface. Conversely, the large and fresh outcrops of the same tuff can be observed around the Pargaringan

Bridge, located along the Pargaringan River, at 1 km south from the Poring River.

Such no-welded to weak-welded tuff consists of relatively hard (soft rock) and soft (very dense soil)

layers. Plenty of piping holes with water flow in the soft part were observed, while some water leakages

along the columnar joints are in the hard part.

(3) Terrace Deposits 1 and 2 (tr 1 and tr 2)

Two stages of terrace plain are confirmed at least, on both banks along the Poring River, as follows:

Terrace deposit in the middle stage (tr 1): 5-10 m height from the recent river flow level in the dry

season

Terrace deposit in the low stage (tr 2) : 2-4 m height from the recent river flow level in the dry

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season

Terrace deposits of both stages consist of loose to slightly dense sandy soil, showing brown color,

containing large amount of round-shaped gravels and boulders of 1-100 cm in diameter.

(4) Talus Deposit 1 (tℓ1)

The talus deposit relatively formed in old age is covering base rock widely, especially around the low to

middle elevation of the river banks and along the creeks. This deposit basically forms convex and hilly

morphological shape, showing gentle slope covered by dense vegetation such as trees and grasses. On the

other hand, this deposit partly cannot be found from morphological information, because it was formed in

the old age and with recent morphological shape.

It was confirmed in this investigation stage that the basement elevation of some old talus deposits shows

2 m lower than the recent riverbed level in Drill No. B-6 (Poring-1 Powerhouse), and 9 m lower than the

recent riverbed level in Drill No. B-8 and B-9 (Poring-2 Intake).

The old talus deposit consists of dense partly loose gravelly to sandy soil, showing brown color, largely

containing angular- to sub-angular- shaped gravels and boulders of 1-150 cm in diameter.

(5) Talus Deposit 2 (tℓ2)

The talus deposit relatively formed in new age is distributed covering base rock, around the lower part of

river banks and along the creeks in small and narrow areas. This deposit forms concave shape, basically

shows bare ground on deposit surface without trees nor grasses.

The new talus deposit consists of loose gravelly to sandy soil, showing brown color, largely containing

angular-shaped gravels and boulders of 1 cm to 2.0 m in diameter.

(6) Landslide (Ls)

Several landslides and potential landslides were located around the project area, by field reconnaissance

after checking the morphological shapes based on the recent topographic maps and the view from

opposite bank of the river. The base geology of these landslides is thick weathered layer of granite, and

extracted landslides seem to increase up the slope.

In this investigation stage, potential landslide blocks were classified to two categories as follows, based

on the probability of the morphological landslide shapes.

a) Landslide (Ls): red solid line in the drawings CW-GEO-03 ~ 08

Landslide shape with high to medium possibility

Steps on the top and middle of the block = relatively clear

Curve of the creek on both sides of the block = relatively clear

Collapse around the end of the block = unclear, locally clear

b) Potential Landslide ((Ls)): pink dashed line in the drawings CW-GEO-03 ~ 08

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Landslide shape with medium to low possibility

Steps on the top and middle of the block = relatively unclear

Curve of the creek on both sides of the block = relatively clear

Collapse around the end of the block = unclear

(7) Riverbed Deposit (rd)

The riverbed deposit consists of loose sand, gravels, and large amount of solid granite boulders of 0.5-5.0

m in diameter. The boulders exist on the full width of the river, especially at the inner elbows of the river.

The gravel parts include very small amount of sandstone which are fine-grained and very solid. In the

Poring River area, large sand sedimentation is very rare.

An enormous number of boulders is assumed to be formed after passing the process that rapid river water

flow have eroded the base granite rock or/and the collapses from the river banks over the years.

Considering the risk of debris flow, it is judged that the big sized boulders such as more than 1 m in

diameter have not flowed down in this 30 years at least.

Figure 3.5.3 shows the geological image profile around the project site.

Source: JICA Survey Team

Figure 3.5.3 Geological Image of the Project Site

3.5.4 SITE GEOLOGY AND EVALUATION

The geotechnical evaluation is described for each proposed structure, considering surface condition by the

field reconnaissance and sub-surface condition by the drilling with in-situ tests such as standard

penetration test (SPT) and permeability test.

Left Bank

River

Gt (very hard)

Gt (highly weathered=sandy soil with boulders)

Tf (weathered, some part of ridge only)

Landslide ?

Gt (highly weathered=sandy soil)

tℓ1 (old talus)

tℓ1 (old talus)

Many hard Gt boulders

tr1 tr2

tℓ2 (new talus)

rd

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(1) Poring-1 Intake

(Surface Condition)

Proposed weir axis is located across the narrow

pass of river which is approximately 20 m in

width. Extremely solid granite outcrops are

discovered in the both bank of river.

Thickness of riverbed deposit is assumed less

than 1 m, poorly containing big sized boulders.

Both banks show steep slope without clear steps,

in which be not assumed to exist the unstable

blocks such as landslide or large talus deposit.

(Sub-surface Condition)

Drill No. B-1 (left bank, total length=10 m): The solid granite appears from the surface (d=0.00 m) to

the end of borehole (d=10.00 m), mostly with CH class in rock grade. The permeability indicates

high value, as 2.18E-03 in 1.00-5.00 m and 19.2 Lu in 5.00-10.00 m section. It is definitive evidence

for high permeability that the oxidized influx soil is observed on the surface of several joints in the

whole section of core samples.

Drill No.B-2 (right bank, total length=10 m): 0.00-0.40 m is top soil. In 0.40-1.60 m, the cracky

granite is observed categorized to CL class. 1.60-10.00 m is the solid granite categorized to

CM-CH classes. The permeability indicates high value, as 1.26E-03 in 1.00-5.00 m and 10.4 Lu in

5.00-10.00 m. It is definitive evidence for high permeability that the oxidized influx soil is

observed on the surface of several joints in the 1.00-5.00 m core samples.

(Geotechnical Evaluation)

The base rock has enough bearing capacity and shear strength for the proposed construction.

The solid rock may appear after excavation of 0.00 to 1.60 m in thickness around the river banks.

The grouting for the high permeable open-joints is required. These open-joints indicate mostly

45-85 deg., with 1-3 m unit.

Both banks seem to be stable without any landslide and large talus deposit.

The risk of debris flow is low, considering few big sized boulders around upstream area of the site.

However, the driftwoods in which diameter approximately less than 40 cm have frequently flowed

down, especially in rainy season.

Source: JICA Survey Team

Weir axis (d/s site) view from upstream side

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Source: JICA Survey Team

Figure 3.5.4 Geological Map around

Poring-1 Intake Weir

Source: JICA Survey Team

Figure 3.5.5 Geological Section along the

Poring-1 Intake Weir Axis

(2) Poring-1 Headrace

(Geotechnical Evaluation)

Foundation of proposed structure is highly weathered granite categorized to D class in rock grade.

In the most section, dense partly loose sandy soil may appear with large amount of hard gravels and

boulders which are 1-2 m in diameter. According as going up the slope, the content rate of gravels

and boulders may decrease and sandy matrix become looser.

Landslides and potential landslides are rare along the Poring-1 Headrace. Conversely, several

potential landslides are assumed to exist around the end section of Poring-1 Headrace and Head

Tank.

The proposed alignment of Poring-1 Headrace is partly passing through the large talus deposit areas.

Consideration shall be given to slope protection measures to ensure the stability of slope and the

water drainage in talus deposit areas which consist of loose sand and gravel containing hard

boulders.

The highly weathered granite may become the supply source of large amount of sandy soil.

Therefore, it is recommended that the cutting slope along the Poring-1 Headrace should be covered

by the dry laid masonry, for protecting the erosion and sediment discharge.

Source: JICA Survey Team Source: JICA Survey Team

Upstream section of Poring-1 Headrace Upstream to middle section of Poring-1 Headrace

Poring-1 Headrace

large talus deposit

Poring-1

Headrace

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Source: JICA Survey Team Source: JICA Survey Team

Middle section of Poring-1 Headrace Middle section of Poring-1 Headrace

(3) Poring-1 Head Tank

(Surface Condition)

The proposed structure is located on the gentle and

wide ridge.

Foundation of proposed structure is highly

weathered granite categorized to D class in rock

grade.

Thick highly weathered zone is assumed under

surface of the foundation, considering the lack of

any fragments and boulders around the site.

Around the proposed structure, several potential

landslides may exist, based on the morphological

analysis.

(Sub-surface Condition)

Drill No.B-4 (total length=20 m):

Base rock cannot be confirmed after

the drilling of 20 m length.

0.00-0.50 m is top soil. 0.50-20.00

m is highly weathered granite

categorized to D class, consisting of

silty sand largely containing gravels

and boulders which are 0.4-3.1 m in

diameter. Below 4.50 m seems

dense, partly remaining the granite

rock texture. Zone of N>50

appears below 4.00m in depth, while

N-value indicates 22 to 35 in the

Narrow talus deposit

Poring-1 Headrace

Poring-1

Headrace

Source: JICA Survey Team

Poring-1 Head Tank Site

Source: JICA Survey Team

Potential landslides around the Poring-1 Head Tank

* Red solid line: Landslide (probability high to medium) * Red dashed line: Potential landslide (probability medium to low)

Waterway-1 Headtank-1

Penstock-1

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depth of 14.00-16.00 m. Ground water is never seen in the borehole.

(Geotechnical Evaluation)

Foundation rock cannot be expected for the proposed structure.

Assumed bearing capacity is 300-600 kPa, considering the N-value indicating more than 50 for

dense sandy soil or dense gravelly soil, below the 4.50 m in depth.

Several potential landslides may exist around the proposed structure, based on the morphological

analysis. It should be considered the slope stability and the drainage during the construction.

Source: JICA Survey Team Source: JICA Survey Team

Figure 3.5.6 Geological Map around

Poring-1 Head Tank

Figure 3.5.7 Poring-1 Head Tank Profile

along the Penstock Alignment

(4) Poring-1 Penstock

(Surface Condition)

The proposed structure is located on the gentle and wide

ridge.

Basement of proposed structure is highly weathered

granite categorized to D class in rock grade.

In upper section of Poring-1 Penstock alignment, thick

highly weathered zone may exist under surface of the

foundation, considering the lack of any fragments and

boulders around the site.

In lower section of Poring-1 Penstock alignment, the

thickness of highly weathered zone may decrease

(assuming 5-10 m), according as going down the slope,

considering granite boulders of 1-2 m in diameter are

discovered on the ridge.

Around the proposed structure, one (1) potential

landslide may exist, based on the morphological

analysis.

Source: JICA Survey Team Drilling No.B-5 along Poring-1 Penstock

Penstock-1

Source: JICA Survey Team Lower Section of Poring-1 Penstock

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(Sub-surface Condition)

Drill No. B-5 (total length=15 m): Base rock cannot be confirmed after the drilling of 15 m length.

0.00-0.30 m is top soil. 0.30-0.70 m is soft to firm silty clay. 0.70-15.00 m is highly weathered

granite categorized to D class, consisting of silty sand largely containing gravels and boulders which

are 0.4-1.5 m in diameter. Below 0.7 m seems dense, partly remaining the granite rock texture.

Zone of N>50 appears below 5.00 m in depth. Ground water is never observed in the borehole.

(Geotechnical Evaluation)

Rock cannot be expected for the foundation of proposed structure.

Assumed bearing capacity is 300-600 kPa, considering the N-value indicating >50 for dense sandy

soil or dense gravelly soil, below 5.00 m in depth around the site of Drilling No.B-5.

One (1) potential landslide may exist around the upper section of structure alignment, based on the

morphological analysis. It should be considered the slope stability and the water drainage during

the construction.

Source: JICA Survey Team Source: JICA Survey Team

Figure 3.5.8 Geological Map

around Poring-1 Penstock

Figure 3.5.9 Geological Profile along Poring-1

Penstock

(5) Poring-1 Powerhouse

(Surface Condition)

The proposed structure is located in gentle slope at the end of ridge and beside the river. The width

of gentle slope is approximately 10-15 m.

The gentle slope is the surface of talus deposit supplied from upstream creek in which have grown

palm trees sparsely and tall grasses densely. Considering the vegetation, this talus is assumed to

have deposited within recent 10-20 years, although large deposit has not been supplied in this 1-2

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years.

In rainy season, the water from upstream creek flows

down on surface of the gentle slope, passing through

the proposed structure site.

The ridge slope upside of structure site is relatively

steep and seems stable, in which hard granite

boulders are partly observed.

(Sub-surface Condition)

Drill No. B-6 (total length=10 m): 0.00-0.20 m is top

soil. 0.20-5.00 m is talus deposit which consists of

moderately loose silty sand, largely containing

angular-shaped gravels. The bottom elevation of

talus deposit is 2 m below the recent riverbed level.

N-value indicates 40-45 (N’=33-36) in 1.00-3.50 m

and 50+ below 4.00 m. 5.00-10.00 m is slightly

weathered granite categorized CM class in rock

grade, hard with oxidized joints. Ground water

level is -5.00 m during drill-operation time.

(Geotechnical Evaluation)

The base rock (CM class) below 5.00 m in depth has

enough bearing capacity for proposed structure.

Lower part of silty sand with gravels is assumed to be old talus deposit, because the bottom elevation

of this deposit exists 2 m below the recent riverbed level. Old talus deposit around the project area

distributes so widely and deeply, that possibly appears on the cutting slope for the structure of

Powerhouse-1.

The thickness of old talus deposit around the proposed cutting slope is estimated 3-4 m in this

investigation stage, although it is difficult to presume accurately because this deposit was formed in

old age and exists not concerned with recent morphological shape.

The water drainage is required on the construction time, considering the water from upstream creek

flows down on surface of the gentle slope, passing through the proposed structure site in rainy

season.

Source: JICA Survery Team

Upside slope of Poring-1 Powerhouse

Source: JICA Survery Team

Proposed Poring-1 Powerhouse Site

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Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.5.10 Geological Map around

Poring-1 Powerhouse

Figure 3.5.11 Geological Profile along

Poring-1 Powerhouse

As an additional topic, relatively new and large talus deposit is discovered at the right bank of Poring

River around 150 m upstream of Poring-1 Powerhouse site. This deposit has been supplied from

large collapse around the off-road in high elevation of river right bank. In future, large volume

sediment might be discharged from this deposit reaching to downstream structure, such as Poring-2

Intake.

proposed powerhouse-1 site

new talus deposit

Source: JICA Survey Team

Proposed Poring-1 Powerhouse Site

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Source: JICA Survey Team

Source: JICA Survey Team

Large collapse around the off-road Large talus deposit at the end of right bank

(6) Poring-2 Intake Weir

(Surface Condition)

Proposed weir axis is located across the narrow pass of river which is approximately 20-25 m in

width.

Solid granite outcrops are discovered in the left river bank.

In left bank, the terrace plain exists at 7 m height from the recent river flow level in dry season.

Upside slope above the terrace plain seems stable containing granite boulders.

In right bank, the solid boulders of granite were observed, which cannot be judged before drilling

that are eroded base rock or floating boulders.

In right bank, unstable factors such as talus deposit or landslide are possibly distributed, considering

the condition of relatively steep slope with ups and downs. The slope stability depends on the

height of cutting slope related with unstable factors scale.

Riverbed deposit slightly contains big sized boulders around the riverbed surface.

(Sub-surface Condition)

Drill No. B-7 (left bank, total length=10 m): 0.00-0.45 m is top soil. 0.45-4.00m is terrace deposit

consists of sandy soil with large amount of round-shaped gravels and boulders of 10-20 cm in

diameter. N-value indicates more than 45 below 2.00 m in depth. In 4.00-6.00 m, cracky granite

is observed categorized to CL class in rock grade. 6.00-10.00 m is the solid granite categorized to

CM classe. The permeability indicates very high value, as 2.53E-02 in 0.00-4.00 m and 42.7 Lu in

6.50-10.00 m. It is definitive evidence for high permeability that the oxidized influx soil is

observed on the surface of joint around 7.90 m in core samples.

Drill No.B-8 (right bank, total length=15 m): 0.00-0.60 m is top soil. 0.60-5.40 m is new talus deposit,

consists of loose to moderately dense silty sand with large amount of angular-shaped gravels and boulders.

5.40-7.00 m is riverbed deposit layer of which elevation is same as recent riverbed level, consists of loose

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sandy gravels showing round-shape. 7.00-13.50 m is old talus deposit, consists of dense silty sand

largely with angular- to sub-angular-shaped gravels of granite and sandstone. 13.50-15.00 m is fresh

granite rock categorized to CH class. N-value indicates 31-45 in 1.00-2.50 m in depth, and 50+ in

8.50-9.50 m sections. The permeability shows very high value, as 4.27E-02 in 0.00-4.00 m and 3.13E-03

in 8.00-10.00 m.

Drill No.B-9 (riverbed, total length=10 m): 0.00-2.70 m is riverbed deposit, consists of loose sandy

gravels showing round-shape. 2.70-9.10 m is old talus deposit, consists of dense silty sand largely

with angular- to sub-angular-shaped gravels of granite and sandstone. 9.10-10.00 m is fresh granite

rock categorized to CH class. N-value indicates 45 in 2.00-2.50 m in depth, and 50+ in 7.00-9.10 m

sections. The permeability shows very high value, as 1.02E-02 in 0.00-4.20 m and 3.13E-03 in

8.00-10.00 m.

(Geotechnical Evaluation)

It was confirmed in this investigation that the basement elevation of old talus deposits shows 9 m

lower than recent riverbed level in Drill No. B-8 and B-9 (see Figure 3.5.13). The old talus deposit

consists of dense gravelly to sandy soil, showing brown colour, largely containing angular- to

sub-angular- shaped gravels and boulders.

Rock cannot be expected for the foundation of proposed structure, considering the excavation cost.

Alternative site was not observed around this weir site, since the old talus deposit may distribute

largely and deeply in the right bank to riverbed area.

It is recommended that alternatively constructing a floating weir. The old talus deposit seems to

have enough bearing capacity (estimate 300-600 kPa) for the small scaled intake weir, based on the

N-value analysis. In case of constructing floating weir, it should be required to consider the

treatment for protecting or decreasing the extreme erosion of sandy soil matrix in old talus deposit.

The risk of debris flow may be low, while the driftwoods in which diameter approximately less than

40 cm have frequently flowed down, especially in rainy season.

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Figure 3.5.12 Geological Condition around Poring-2 Intake

Source: JICA Survey Team

Figure 3.5.13 Geological Section along Poring-2 Intake Weir Axis

Weir axis view from left bank

Large old talus in right bank

Intake-2

old talus

50m

Source: JICA Survey Team

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(7) Poring-2 Headrace

(Geotechnical Evaluation)

Basement of proposed structure is highly weathered granite categorized to D class in rock grade. In

the most section of waterway basement, dense partly loose sandy soil may appear with large amount

of hard gravels and boulders which are 1-4 m in diameter. According as going up the slope, the

content rate of gravels and boulders may decrease and sandy matrix become looser.

Comparing to the condition along Waterway-1, landslides and assumed landslides are more

recognized along the Poring-2 Headrace. Especially, several potential landslides in small scale are

assumed to exist around the end section of Poring-2 Headrace and Head Tank.

The proposed alignment of Poring-2 Headrace is partly passing through the large talus deposit areas.

It should be considered the slope stability and the water drainage in talus deposit areas which consist

of loose sand and gravel containing hard boulders.

The highly weathered granite may become the supply source of large amount of sandy soil.

Therefore, it is recommended that the cutting slope along the Poring-2 Headrace should be covered

by the dry laid masonry, for protecting the erosion and sediment discharge.

Source: JICA Survey Team

Large collapse around the off-road in high elevation of left bank is providing large amount of

sediments to the creek (see Appendix 1). Approximately 80 m downstream point of Intake-2, the

Waterway-2 alignment is passing through this creek. At the moment (May 2015), the end of

sediments was reached to 100 m in height above the Poring-2 Headrace. It is recommended to

regularly monitor the expansion of these collapse and sediments, in consideration of the risk of

sediments influx to the Poring-2 Headrace.

Slope-cut of canal near the Poring-1 Powerhouse

Waterway-2

Downstream section of Poring-2 Headrace

Waterway-2

Middle section of Poring-2 Headrace

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Source: JICA Survey Team

(8) Poring-2 Head Tank

(Surface Condition)

The proposed structure is located on the gentle and wide ridge in high elevation closed to watershed.

Foundation of proposed structure is highly weathered granite categorized to D class in rock grade.

Highly weathered granite consists of dense to loose sandy soil with poor boulders, based on the

observation of outcrops along the off-road.

The proposed structure may be located at the upper portion of potential landslide which shows

relatively clear morphological factors such as steps on the top and middle, curve of the creek in the

both sides, and collapse around the end.

Source: JICA Survey Team Source: JICA Survey Team

Potential landslide around Poring-2 Head Tank Outcrop of Highly Weathered Granite

potential landslide

Head Tank-2

Large collapse providing sediments to the creek upside of Waterway-2

Poring-2 Headrace

End of discharged sediments

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Source: JICA Survey Team Source: JICA Survey Team

Drilling No.B-10 site Downside slope of Drilling No.B-10 site

(Sub-surface Condition)

Drill No.B-10 (total length=20 m): Bedrock can be confirmed below 17.80 m in depth. 0.00-0.30 m

is top soil. 0.30-17.80 m is highly weathered granite categorized to D class. 0.30-3.25 m is soft

clayey silt. 3.25-17.80 m consists of moderately dense sandy silt with very poor gravels, partly

remaining granite rock texture. N-value indicates 4 to 13 in depth of 1.00-5.50 m, 19 to 21 in depth

of 6.00-15.50 m, and 31 to 36 in depth of 16.00-17.50 m. Ground water was not observed in the

borehole.

(Geotechnical Evaluation)

Rock cannot be expected for the foundation of proposed structure, considering too deep (17.80 m)

excavation is necessary to reach the bedrock.

For basement of structure, it is should be judged which to choose between the layer of N>20 after

excavation of 6 m depth, and the layer of N>30 after excavation of 16 m depth.

Several potential landslides may exist around the proposed structure, based on the morphological

analysis. It should be considered the slope stability and the water drainage during the construction.

Source: JICA Survey Team

Figure 3.5.14 Geological Map around Poring-2 Head Tank

50m

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Source: JICA Survey Team

Figure 3.5.15 Geological Profile along Poring-2 Head Tank

(9) Poring-2 Penstock

(Surface Condition)

Most part of proposed Penstock-2 is located on the relatively narrow ridge.

Basement of the middle section (50 % of alignment length) is formed by tuff, with consideration that

fragments of tuff are discovered around the ridge.

In the upper and lower sections, basement of Penstock-2 is highly weathered granite categorized to D

class in rock grade.

In upper section of Penstock-2 alignment, thick highly weathered zone may exist under surface of the

foundation, considering poor distribution of fragments and boulders around the site.

In lower section closed to proposed Powerhouse-2 site, the old talus deposit is largely covered

around the concave-shaped slope. This deposit is eroded by water flow of creek in centre of the

concave- shaped slope, and forming gully erosion.

Around the proposed structure, no potential landslide may exist, based on the morphological

analysis.

(Sub-surface Condition)

Drill No.B-11 (total length=20 m): 0.00-0.20 m is top soil. 0.20-8.00 m is highly weathered tuff

categorized to D class, consisting of light-brown silty sand with poor rock fragments, indicating 5 to

38 in N-value. 8.00-20.00 m is moderately weathered tuff categorized CL class in rock grade for

soft Tertiary rock, showing fine to medium grained, grey coloured, very dense indicating 50+ of

N-value, silty to sandy cores like a hardpan. Ground water is never seen in the borehole.

(Geotechnical Evaluation)

In upper section, rock cannot be expected for the foundation of proposed structure. Assuming the

condition of the upper section is similar to the Headtank-2 situation, it is should be judged which to

choose between the layer of N>20 after excavation of approximately 6 m depth, and the layer of

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N>30 after excavation of 16 m depth.

In middle section of alignment, the moderately weathered tuff of 50+ in N-value is expected for

basement of proposed structure, appearing 8 m in depth below the surface. Allowable bearing

capacity is estimated to be 300 kPa.

Around the proposed structure, potential landslide is not existing with the exception of the high

elevation area closed to the Poring-2 Head Tank site.

In lower section closed to proposed Poring-2 Powerhouse site, the old talus deposit is largely existing

around the concave-shaped slope. It is recommended that Poring-2 Penstock alignment should be

deployed with avoid of the concave centre in which assumed to distribute the thick talus deposit. In

addition, it is required to attend with the slope stability and the treatment such as water drainage for

protecting the erosion of talus deposit.

Source: JICA Survey Team, photo taken by JICA Survey Team

Figure 3.5.16 Geological Map around Poring-2 Penstock

Middle section of Poring-2 Penstock

Penstock-2

Lower section of Poring-2 Penstock

Penstock-2

centre of old talus deposit

100m

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Source: JICA Survey Team

Figure 3.5.17 Geological Profile along Poring-2 Penstock

(10) Poring-2 Powerhouse

(Surface Condition)

Proposed structure is located on the flat plain of 15-20 m in width, which is the surface of terrace

deposit existing at 8-10 m height from the recent river flow level in dry season.

In the upside slope behind proposed Powerhouse-2, the old talus deposit is largely existing around

the concave-shaped slope, of which thickness assumed to be 5 m in maximum. While the solid

granite rock wall of 4-8 m in height is existing between this concave-shaped slope and the proposed

site.

Solid granite outcrops are continuously distributed around the river area, which is categorized to

CH-CM class in rock grade. The upper end of these outcrops reaches 4-5m in height from recent

riverbed level in both banks of river.

(Sub-surface Condition)

Drill No.B-12 (total length=10 m): 0.00-0.15 m is top soil. 0.15-1.70 m is new talus deposit which

consists of soft brown sandy silt, containing angular-shaped fragments. 1.70-5.80 m is terrace

deposit which consists of gray sandy silt containing round-shaped fragments and boulders of 40 cm

in maximum diameter. N-value indicates very low, such as 3 to 8 in 1.00-5.50m section.

5.80-10.00 m is fresh granite categorized CH class in rock grade. Ground water level is -1.80 m

during drill-operation time.

(Geotechnical Evaluation)

The base rock appearing 5.8 m in depth below the surface is very suitable for the foundation of

proposed Powerhouse-2.

Upper layer consisting of talus and terrace deposit is not suitable for the foundation of structure,

considering low N-value such as 3 to 8 in this layer.

The solid granite wall seems to be good protection from the instability of upside slope, for the

proposed structure. It is recommended to deploy the structure without the large slope-cutting as

reaching to the upside slope, if it is possible.

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The water drainage layout is required with consideration of the existence of shallow ground water

level and creek water flow.

Source: JICA Survey Team

Source: JICA Survey Team Source: JICA Survey Team

Figure 3.5.18 Geological Map

around Poring-2 Powerhous

Figure 3.5.19 Geological Profile along Poring-2

Powerhouse

Poring-2 Powerhouse Site

Solid granite wall

Solid granite around riverbed

olid granite wall

Solid granite wall protecting Poring-2 Powerhouse Site

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3.5.5 CONSTRUCTION MATERIALS

For the rock materials such as stone masonry can be obtained from the riverbed deposit. The granite

boulder is very solid and suitable for the stone masonry. For crushing the solid and massive boulder to

make rock materials of suitable size, it is recommended to use blasting.

Other construction materials such as concrete aggregate and sand are scheduled to be purchased from

Tarutung with consideration a) blasting is required for crushing, b) concrete volume is relatively small, c)

higher cost, and d) additional permission required.

3.5.6 SEISMIC RISK STUDY

Indonesia is located in a tectonically very active area at the point of convergence of the three major plates

and nine smaller plates creating a complex network of plate boundaries. The existence of interactions

between these plates puts Indonesia in an earthquake prone region.

The Government of Indonesia published the Seismic Hazard Map “Peta Zonasi Gempa Indonesia” in

2010. This is the Indonesian National Design Code and is widely used for planning and design of

earthquake resistant infrastructure. These maps includes maps of peak ground acceleration (PGA)

representing three levels of seismic hazard at 500, 1,000, and 2,500 years or have the possibility to exceed

10% in 50 years, 10% in 100 years, and 2% in 50 years as shown below.

PGA at bedrock having a probability

of exceedance of 10% in 50 years PGA at bedrock having a probability of exceedance of 10% in 100 years

PGA at bedrock having a probability of exceedance of 2% in 50 years

Source: Peta Zonasi Gempa Indonesia, PU, 2010

Figure 3.5.20 Indonesia Earthquake Hazard Map

For major facilities in hydropower projects, the design requirements shall satisfy both of the OBE15 and

MDE16 in accordance with the Earthquake Design and Evaluation of Concrete Hydraulic Structures

15 Operating Basis Earthquake (OBE) is a level of ground motion that is reasonably expected to occur within the service life of the project, that is, with a 50-percent probability of exceedance during the service life. (This corresponds to a return period of 72 years for a project with a service life of 50 years). 16 Maximum Design Earthquake (MDE) is the maximum level of ground motion for which a structure is designed or evaluated. The MDE

0.3-0.4g 0.4-0.5g 0.5-0.6g

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(EM1110-2-6053).

Furthermore, critical structures such as intake weir are the structures whose failure will result in loss of

life shall satisfy not MDE but MCE17.

On the other hand, Indonesia has a design earthquake which is defined in the national standard (SNI), and

has widely applied the 10% probability earthquake in 50 years (SNI 03-1726-2002 Standard Perencanaan

Ketahanan Gempa untuk Struktur Bangunan Gedung, Reference 2002). Thus, for a structure other than

intake weir, as the largest earthquake may be assumed to apply it instead of the MDE earthquake.

The following table summarizes the relation of PGA and its probability of earthquake in the project area.

The correlation of the PGA and probability of earthquake revealed the range of PGA at each frequency of

earthquake.

Table 3.5.1 PGA and Probability of Earthquake in the Project Area

Probability of Exceedance

(Pe, %)

Exposure Time (Te, years)

Return Period (Tr=-Te/ln(1-Pe),

years)

Annual probability of exceedance (λm=1/Tr)

“Peta Zonasi Gumpa 2010”

Remarks Minimum PGA (g)

Maximum PGA (g)

50% 50 72 0.01386 (0.18) (0.22) OBE 10% 20 190 0.00527 (0.24) (0.30) 10% 50 475 0.00211 0.30 0.40 Indonesia 10% 100 949 0.00105 0.40 0.50 MDE 2% 50 2,475 0.00040 0.50 0.60 MCE

Source: JICA Survey Team

Source: JICA Survey Team

Figure 3.5.21 Correlation between PGA and Annual Probability of Exceedance ground motion has a 10% chance of being exceeded in a 100-year period, (or a 1,000- year return period). For critical structures (part of a high hazard project and whose failure will result in loss of life), the MDE ground motion is the same as the MCE ground motion. 17 Maximum Considerable Earthquake (MCE) is defined as the largest earthquake that can reasonably be expected to occur on a specific source, based on seismological and geological evidence. Alternatively, MCE is calculated with a uniform probability of exceedance of 2% in 50 years (return period of about 2,500 years).

(0.18g)

(0.23g)

0.30g

0.40g

0.50g

(0.22g)

(0.30g)

0.40g

0.50g

0.60g

0.0001

0.0010

0.0100

0.1 1.0

An

nu

al P

rob

abil

ity

of E

xcee

dan

ce, λ

m

Peak Ground Acceleration (PGA, g)

MDE: 10% PE in 100-year (= 949-year Return Period)

OBE: 50% PE in 50-year (=72-year Return Period)

Design Earthquake: 10% PE in 50-year(=475-year Rerutn Period)

MCE: 2% PE in 50-year (=2,475-year Return Period)

10% PE in 20-year (=190-year Return Period)

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

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With the consideration of 20 years service life, the assumed PGA applied the minimum PGA.

Accordingly, the design PGA applied in this project is tablulated below.

Table 3.5.2 Design Peak Ground Acceleration for the Project

Design Earthquake OBE MDE or MCE

Intake Weir 0.18g 0.50g

Other Structures 0.18g 0.30g Source: JICA Survey Team

The peak acceleration at the ground surface can be obtained using the following equation:

PGAM = FPGA × SPGA

where, PGAM is the value at the peak ground acceleration based on the classification of the site and FPGA

is the amplification factor for the PGA.

To get the peak ground acceleration at ground surface, the classification of the site should be determined

for a layer thickness of 30 m in accordance with the definitions in the following table which are based on

the correlation of the results of the soil investigation field and laboratory.

Among the major structures in this project, intake weir and powerhouse are designed to be located on the

exposed rock (FPGA =0.8), and other major structures such as headrace, head tank, and anchor blocks for

penstock is located on the weathered rock (FPGA=1.0).

Table 3.5.3 Classification of the Site for Ground Surface

Site Classification Shear Velocity

Vs (m/sec)

N-Value Undrained Shear

Strength, Su (kPa)

PGA

≤ 0.1

PGA

= 0.2

PGA

= 0.3

PGA

= 0.4

PGA

≥ 0.5

Hard Rock (SA) Vs ≥ 1,500 N/A N/A 0.8 0.8 0.8 0.8 0.8

Rock (SB) 750 < Vs ≤ 1,500 N/A N/A 1.0 1.0 1.0 1.0 1.0

Very Solid Soil and Soft Rock (SC)

350 < Vs ≤ 750 N ≥ 50 Su ≥ 100 1.2 1.2 1.1 1.0 1.0

Medium Soil (SD) 175 < Vs ≤ 350 15 < N ≤ 50 50 < Su ≤ 100 1.6 1.4 1.2 1.1 1.0

Soft Soil (SE) Vs ≤ 175 N < 15 Su < 50 2.5 1.7 1.2 0.9 0.9

Other Soil (SF) Locations that require geotechnical investigation and analysis of specific response

SS SS SS SS SS

Note: SS=Locations that require geotechnical investigation and analysis of specific response.

Source: Peta Zonasi Gempa Indonesia, PU, 2010

As a result, the design earthquake for Poring-1 and Poring-2 is summarized below.

Table 3.5.4 Design Earthquake Coefficient

Design Earthquake OBE MDE or MCE

Intake Weir Kh=0.8×0.18=0.14 Kh=0.8×0.50=0.40

Powerhouse (Poring-1 and Poring-2) Kh=0.8×0.18=0.14 Kh=0.8×0.30=0.24

Other Structures Kh=1.0×0.18=0.18 Kh=1.0×0.30=0.30 Source: JICA Survey Team

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(Blank Page)

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Preparatory Survey on North Sumatra Mini 4-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 4 OPTIMIZATION OF DEVELOPMENT PLAN

4.1 OPTIMIZATION OF DEVELOPMENT PLAN

In undertaking this study, a review of the development plans for the project has been undertaken

considering the existing plans proposed in the pre-feasibility study, legal and other limitations imposed by

existing regulations and permit requirements, and design issues that were determined during the site visits,

additional and supplementary surveys, and analysis undertaken as part of this study. The results of the

review for the optimization of the development plans are described in this chapter.

4.1.1 LIMITATIONS OF DEVELOPMENT PLAN

To establish hydropower development plan, the project is premised on applying the FIT program, which

is in accordance with the ESDM Regulation on Purchase of Electricity for connection of Renewable

Energy Generation Plant (REGP). The following are the limitations for applying the FIT program in the

development of small hydropower facilities:

No larger than 10 MW in nameplate capacity

To be connected to PLN’s distribution system at 20 kV or lower voltage level

To study the alternative layout plan, there are limitations for the application of the location permit

(Izin Lokasi) and environmental monitoring plan (UKL/UPL), which the developer has already

obtained prior to this optimization study.

Location permit (Izin Lokasi) has been obtained from North Tapanuli Regency where the project is

located. If the project is located over two regencies, the location permit should be newly obtained

from North Sumatra Province and this will likely result in the delay of implementation,

The developer has already obtained the environmental monitoring plan (UPL/UKL) for this project.

The limitations for the UPL/UKL are that the installed capacity shall not be larger than 10 MW, the

weir height should not be greater than 15 m, and the transmission line should not be larger than 150

kV. Development plans outside of these limitations require a full environmental impact assessment

(AMDAL).

The development plans were studied taking into account the above limitations.

4.1.2 OPTIMIZATION OF DEVELOPMENT PLAN

In the course of the optimization of the development plan, the studies for the optimization of the installed

capacity, maximum plant discharge, and facilities layout were undertaken. Each parameter is a key

parameter to determine the others, so that repeated calculations are required.

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In this project, the installed capacity is the most critical parameter to apply the FIT program. Therefore,

repeated calculations were carried out based on the assumption of installed capacity (not more than 10

MW). The flowchart of the optimization is illustrated in Figure 4.1.1 below.

Source: JICA Survey Team

Figure 4.1.1 Flowchart of Optimization of Dvelopment Plan

4.2 INSTALLED CAPACITY

More river discharge is available in this project than the requirement of 10 MW, so that the installed

capacity is not determined by the maximum plant discharge, but the maximum plant discharge is

determined by the installed capacity of 10 MW under the limitation of the FIT program. Therefore, it is

determined by the optimization of the unit generation cost.

The maximum plant discharge is selected to be optimized by comparing the benefit and cost from five

alternatives not larger than 10 MW under the FIT program and from five more alternatives larger than 10

Review of the Pre-FS

Law and Permissions Review of Hydrology

Topographic Survey Geological Investigation

Layout Study

Site Reconnaissance

Selection of Intake Weir and Headrace Channel Site

Selection of Penstock and Powerhouse Site

Calculation of Effective Head

Determination of Maximum Plant Discharge

Calculation of Energy Generation

Estimate of Construction Cost and Financial Evaluation

Determination of Optimum Project Development Plan

Selection of Installed Capacity

Hydrology

Layout Study

Layout Study

Head Loss

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MW which apply the normal tariff for middle-scale hydropower plant in Indonesia. The maximum plant

discharge, optimum waterway layout, construction cost, and energy generation are studied respectively,

and compared with the net present value (discount rate, r=8.2%).

Accordingly, the installed capacity of 10 MW is selected based on the largest net present value among the

ten alternatives. Therefore, the effective head and maximum plant discharge are studied to achieve this 10

MW.

4.3 OPTIMIZATION OF LAYOUT

4.3.1 LAYOUT STUDY OF PORING-1 INTAKE WEIR AND HEADRACE

To determine the position of weir, the criteria are: 1) exposed foundation rock or shallow excavation

toward the rock, 2) low risk for erosion of the downstream river bank by flood flow, 3) easiness of river

closure and diversion during construction, 4) no impact on upstream sections due to backwater of weir,

and 5) convenience of construction and O&M of intake facilities.

Two alternative locations and headrace channel routes are shown in the following Figure 4.31. The

schematic design is studied for the alternatives, which are included for optimal arrangement in

consideration of the headrace extension.

Alternative-1 (Upstream Weir Site)

The difference of elevation of 17 m may be utilized additionally for power generation compared with

Alternative-2 (Downstream Site). The upstream intake weir site is expected to have more stable rock

slope and foundation according to the site conditions. However, a larger volume of rock excavation is

expected. It is noted that there are no impacts on the upstream cultivated land (paddy field) by the

construction of intake weir in this area.

To access the construction site, the existing bike road which is about 2.5 m wide and 1.15 km long

will be used after improvement to allow construction traffic access. No particular problems were

observed for this improvement work because the slope is relatively gentle. In comparison with the

alternative downstream weir location, the length of headrace channel-1 will be increased by 0.41 km,

but the length of the newly constructed access road will be decreased by 0.45 km.

Alternative-2 (Downstream Site)

The intake weir at the downstream location can be expected to have stable foundation based on the

known geology in the area. Also, rock excavation is expected to be smaller than Alternative-1

(Upstream Site). Existing upstream facilities will not be impacted by the intake weir construction in

this location.

For access to the construction site, the bike road of about 2.5 m width on the right bank side will be

used. In order to undertake construction of the intake weir, this road will need to be improved for a

distance of 1.15 km. In addition, new access road is required over a distance of 0.45 km.

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Alternative-1 Upstream Intake Site Alternative-2 Downstream Intake Site Source: JICA Survey Team

Figure 4.3.1 Alternative Location of Poring-1 Intake Weir

Poring-1 Headrace is designed to intake the river discharge from the full supply level of the intake weir,

and to go along almost same elevation through the relatively gentle slope on the left bank with a 2.5 km

long channel to connect to the Poring-1 Head Tank. The channel crosses several rivers on the way but the

crossing or diversion of these rivers is not considered to be a significant impediment because the rivers

have small catchment areas and small discharges. The waterway near the head tank is located in a rather

steeper and weathered area, increasing the risk for sliding. It is recommendable to apply a waterway with

box culverts.

Accordingly, the two alternative layouts for Poring-1 Intake Weir and Headrace in Figure 4.3.2 were

studied and compared.

Source: JICA Survey Team

Figure 4.3.2 Alternative Layout of Poring-1 Intake Weir and Headrace

Intake Alt.-1 U/S Site

Intake Alt.-2D/S Site

Headrace Alt.-2L=2.50 km

Headrace Alt.-1 L=2.91 km

Head Tank Alt.-1

Head Tank Alt.-2

Access RoadL=0.45 km

Poring River

Existing Bike Road L=1.15 km

Public Road

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The plant discharge used in order to ensure maximum output of 10 MW has been set. Within this

limitation, the unit construction cost is compared considering the cross section, slope, energy generation,

construction cost of intake weir and headrace channel, and construction method.

Alternative-1 has 2.6 GWh/year more annual power generation compared to Alternative-2. However, the

construction cost is higher than that of Alternative-2. Alternative-2 will be more economical. It is noted

that both alternatives for the intake weir will be constructed on hard rock, and there are no impacts on the

environment.

Therefore, Alternative-2 (donstream layout) was selected.

4.3.2 LAYOUT STUDY OF PORING-2 INTAKE WEIR AND HEADRACE

Poring-2 Intake Weir in the Pre-FS is located in the mouth of a 70 m high waterfall. Therefore, the 800 m

long section upstream toward Poring-1 Powerhouse is a candidate location of Poring-2 Intake Weir. An

alternative such as direct connection from Poring-1 Powerhouse to Poring-2 Headrace instead of

construction of Poring-2 Intake Weir was also studied for comparison.

It is designed to go through sparse rubber plantation on the left bank via a 2.5 km long channel to connect

to Poring-2 Head Tank. On the way, the headrace crosses the existing village (Siantar Naipospos Village)

and existing public road, in which around 30 houses including church and school are scattered on the

slope.

Alternative-1 Downstream Site:

The weir axis proposed in the Pre-FS is located slightly upstream of the waterfall where the Poring

River flows gently. Because of the exposed rock, the foundation is stable for constructing the weir.

The river width is enough for diversion works. However, the difference of elevation between

Poring-1 Tailrace is approximately 60 m.

Alternative-2 Upstream Site:

The river goes to the right in front of Poring-1 Powerhouse and then narrows to 20 m wide at 100 m

downstream. Poring-2 Intake Weir is designed here because: 1) this position contains fewer boulders

compared with the upper section where the river is covered with huge boulders and 2) the river flows

relatively quietly and not in supercritical flow in this section.

As a result of geological investigation, rock was exposed in the left bank but it is widely covered by

old talus deposit in the right bank. It is possible to construct a floating type weir but the

countermeasures to prevent erosion and seepage of foundation will be required.

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Alternative-2 Upstream Intake Site Alternative-1 Downstream Intake Site Source: JICA Survey Team

Figure 4.3.3 Alternative Location of Poring-2 Intake Weir

Alternative-3 Direct Connection

The alternative to cancel the Poring-2 Intake Weir and make a connection directly from Poring-1

Powerhouse to Poring-2 Headrace was studied. Diverting the power discharge through the pipe

spillway enables the operation of Poring-2 Powerhouse during the maintenance period of Poring-1

Powerhouse. At the end of the pipe spillway, additional energy dissipator is designed to release the

discharge to the tailrace.

The design and operation and maintenance concept for the direct connection is summarized below:

Bypass of discharge: Diverting the power discharge through the pipe spillway and directly

connecting to Poring-2 Headrace during the non-operation of Poring-1

Powerhouse.

Impact on tailrace: Energy dissipater is designed to reduce the discharge velocity and

release to the tailrace. To reduce the water surface fluctuation of the

tailrace channel, wider channel is designed to reduce the velocity.

Design change due to

weir cancellation:

The intake facility and sand trap basin are also cancelled in the case of

cancellation of Poring-2 Intake Weir since it is not taking river water.

It is noted that intake gate is required at the connection channel

between Poring-1 Tailrace and Poring-2 Headrace.

Additional facility: Regardless of the operation of Poring-1 Powerhouse, the discharge for

Poring-2 Powerhouse shall be controlled. To satisfy this condition,

Poring-1 Sand Trap Basin is designed to have two bays to prevent

stopping the discharge by flushing the sedimentation.

It is noted that the unforeseeable accident of Poring-1 Headrace and its

repair period are not considered in the above assumption.

Accordingly, the following three alternative layouts for Poring-2 Intake Weir and Headrace were studied

and compared.

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Source: JICA Survey Team

Figure 4.3.4 Alternative Layout of Poring-2 Intake Weir and Headrace

Accordingly, Alternative-3 (Direct Connection), which is not dominant in terms of geology, will be the

most economical and advantageous in risk mitigation and environment aspects, despite of a rather

complicated operation compared with the other alternatives.

Therefore, Alternative-3 (Direct Connection) was selected.

4.3.3 LAYOUT STUDY OF PORING-1 PENSTOCK AND POWERHOUSE

The location of powerhouse is studied together with the alignment of the penstock. The penstock

alignment shall be along the ridge line and as straight as possible to prevent sliding and rolling stones

considering easiness of construction. The powerhouse is located at the end of the penstock, which is

arranged to have the shortest length along the ridge slope. The criteria for the location of powerhouse are

generally the following: 1) stable foundation rock, 2) safe location from flood discharge, and 3) no risk

for landslide. Furthermore, Poring-1 Powerhouse shall be located in the middle of the available head

between Poring-1 and Poring-2. Accordingly, the following two layouts are considered for Poring-1

Penstock and Powerhouse.

It is noted that the further upstream alternatives are not suitable because of lower head due to continuous

cascades toward the upstream and longer distance between the head tank and the river. Furthermore, the

further downstream alternatives are not considered because of the relatively large tributary with landslides

at about 250 m downstream of the head tank.

Alternative-1 Upstream Site

Penstock alignment is on the ridge line, and the powerhouse is located on a relatively gentle slope at

the foot of the penstock slope where the Poring River is curving but the flood flow does not reach the

powerhouse yard.

Intake Alt.-2 U/S Site

Headrace Alt.-1L= 1.93 km

Headrace Alt.-3L=2.58 km Headrace Alt.-2

L=2.45 km

Head Tank Alt.-2

Head Tank Alt.-3

Public Road

Poring River

Siantar Naipospos

Head Tank Alt.-1

Intake Alt.-3 Weir Cancel

Intake Alt.-1 D/S Site

Bike Road

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Alternative-2 Downstream Site

Penstock alignment is on the ridge line but longer than in Alternative-1. Powerhouse is located on

exposed hard rock site, but the yard is on the slope and the space is limited so that the excavation is

larger.

Alternative-1 Upstream Powerhouse Site Alternative-2 Downstream Powerhouse Site Source: JICA Survey Team

Figure 4.3.5 Alternative Location of Poring-1 Powerhouse

Accordingly, the following two alternative layouts for Poring-1 Penstock and Powerhouse were studied

and compared.

Source: JICA Survey Team

Figure 4.3.6 Alternative Layout of Poring-1 Penstock and Powerhouse

Accordingly, Alternative-1 will be the most economical and it will have more available flat construction

space as well as require less excavation for the powerhouse.

Penstock Alt.-1 L=430 m

Penstock Alt.-2 L=554 m

Head Tank

Tributary with Large Landslide

Powerhouse Alt.-2 D/S Site

Powerhouse Alt.-1 U/S Site

Headrace Channel Collpased Deposit

Headrace Channel

Poring River

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Preparatory Survey on North Sumatra Mini 4-9 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Therefore, Alternative-1 (Upstream Layout) was selected.

4.3.4 LAYOUT STUDY FOR PORING-2 PENSTOCK AND POWERHOUSE

Based on the penstock alignment on the ridge line, Poring-2 Powerhouse is located on a relatively gentle

slope at the foot of the penstock slope, which is geologically stable and where the flood flow does not

reach the powerhouse yard. The following two alternative layouts are selected for comparison:

Alternative-1 Upstream Site

Penstock is aligned in the shortest route along the ridge line but the slope is steep and mostly covered

by thick talus deposit. Powerhouse is located on the exposed rock but there is no flat space along the

river. The Poring River around this site is continuously cascading. The difference of elevation is 50

m higher than in the Alternative-2 Downstream Site. The route to access this site is limited due to the

steep slope around this site. Therefore, the road construction will be longer than in Alternative-2.

Alternative-2 Downstream Site

Penstock is aligned along the narrow edge line so that the longitudinal gradient is gentle and the

length of penstock will be longer. Powerhouse is located at the edge of an alluvial fan and the

powerhouse yard will be constructed on the stable terrace of the river. The geological conditions are

sufficient for the powerhouse because rock foundation is observed at a depth of 6.0 m.

Alternative-1 Upstream Powerhouse Site Alternative-2 Downstream Powerhouse Site Source: JICA Survey Team

Figure 4.3.7 Alternative Location of Poring-2 Powerhouse

Accordingly, the following two alternative layouts for Poring-2 Penstock and Powerhouse were studied

and compared:

Final Report

Preparatory Survey on North Sumatra Mini 4-10 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 4.3.8 Alternative Layout of Poring-2 Penstock and Powerhouse

Accordingly, Alternative-2 will be more economical, has better geological conditions and shorter access

to the powerhouse. Therefore, Alternative-2 (Downstream Layout) was selected.

4.4 HEAD LOSS AND EFFECTIVE HEAD

4.4.1 EFFECTIVE HEAD

The effective head is the total water head acting on the hydraulic turbine during operation, which is the

difference of water head before and after the turbine. The effective head for Francis turbine (reaction

type) is calculated by the following equation:

He Hg HL1 HL2 HL3

Where,

Hg is the Gross Head, the difference in elevation between the water level at the intake weir and at the

tailrace site,

He is the Effective Head,

HL1 is the head loss between intake and head tank,

HL2 is the head loss between head tank and turbine,

HL3 is the head loss between draft pond and tailrace outlet, and

v22/2g： is the velocity head at the tailrace weir.

Penstock Alt.-2L=862 m

Penstock Alt.-1 L=568 m

Head Tank Public Road

Poring River

PowerhouseAlt.-2 D/S Site

Powerhouse Alt.-1 U/S Site

Poring River

Project Road to Powerhouse

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Preparatory Survey on North Sumatra Mini 4-11 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

v22/2g HL3 is calculated from critical water depth at the tailrace overflow weir crest, and the head

loss between the intake and head tank (HL1 is equivalent to the elevation difference of waterway invert

slope. The head loss between head tank and inlet of turbine (HL2 is related to the discharge and flow

velocity depending on the two-unit and one-unit operation as shown below.

Accordingly, the relationship between head loss and discharge is tabulated depending on the unit number

of operation.

Table 4.4.1 Head Loss and Discharge

Item Poring-1 Poring-2

2-unit Operation 1-unit Operation 2-unit Operation 1-unit Operation

Head Loss 6.00 m 2.00 m 11.10 m 3.30 m

Loss Coefficient 212,179 × 10-6 × Q2 222,158 × 10-6 × Q2 478,143 × 10-6 × Q2 527,907 × 10-6 × Q2

Source: JICA Survey Team

Consequently, the calculation of effective head is summarized in Table 4.4.2 below.

Table 4.4.2 Design Water Level Item Poring-1 Poring-2

Intake Water Level (at Intake Weir) Full Supply Water Level (FSL)

EL. 646.5 m

EL. 441.6 m

Intake Water Level (at Head Tank) Full Supply Water Level (FSL) Rated Water Level Minimum Operational Level (Two-unit)Minimum Operational Level (One-unit)

EL. 641.0 m EL. 641.0 m EL. 640.8 m EL. 640.6 m

EL. 436.4 m EL. 436.4 m EL. 436.2 m EL. 436.0 m

Tail Water Level Flood Water Level Water Level at Two-unit Operation Water Level at One-unit Operation Low Water Level (No-flow)

EL. 441.5 m EL. 441.8 m EL. 441.5 m EL. 441.1 m

EL. 192.7 m EL. 193.0 m EL. 192.7 m EL. 192.3 m

Head Loss Head Loss due to Two-unit Operation Head Loss due to One-unit Operation

6.0 m 2.0 m

11.1 m 3.3 m

Gross Head and Net Head Maximum Gross Head: Hg Maximum Net Head: Hmax *1 Design Head (Rated Head): Hd *2 Minimum Net Head: Hmin *3

646.5-441.1=205.4 m

641.0-441.5-2.0=197.5 m 641.0-441.8-6.0=193.2 m 640.6-441.8-6.0= 192.8 m

441.6-192.3=249.3 m

434.4-192.7-3.3=240.4 m 436.4-193.0-11.1=232.3 m436.0-193.0-11.1= 231.9 m

Note: *1=1-unit operation at rated output, *2=2-unit operation at rated output, *3=2-unit operation when guide vanes are fully opened Source: JICA Survey Team

4.4.2 TYPE AND EFFICIENCY OF TURBINE AND GENERATOR

(1) Selection of Turbine and Generator

The type of turbine is selected from the following selection chart based on a maximum plant discharge of

6.0 m3/s and rated effective head of 193.2 m for Poring-1, and maximum plant discharge of 5.0 m3/s and

Final Report

Preparatory Survey on North Sumatra Mini 4-12 Nippon Koei Co., Ltd.

Hydropower Project (PPP Infrastructure Project)

rated effective head of 232.3 m for Poring-2.

Vertical Francis, Turgo impulse, and Pelton turbines are also within the applicable range, but horizontal

Francis turbine is selected because it is the most widely applied in small- to medium-scale hydropower

plants and accordingly, the most cost effective.

Figure 4.4.1 Turbine Selection Chart

The type of generator selected is not an induction type but synchronous type, which enables the supply of

electricity independently from the transmission system.

Synchronous type generators cost more than induction type generators because they require an additional

exciter in order to synchronize voltage, frequency, and phase with the system.

(2) Number of Unit and Unit Capacity

The number of unit (turbine and generator) is normally more than two units for hydropower projects

considering the following:

Efficiency of Turbine and Generator: In case of one-unit operation, the plant discharge for power

generation is smaller in range due to larger minimum discharge, and the efficiency of turbine and

generator is smaller at low plant discharge operations,

Operation and Maintenance: More than two units enable the inspection and overhaul of the turbine

and generator one by one during the dry season so that it is more economical.

In case of 2-units × 5,000 kW, such periodic inspection is normally carried out during the dry season

when the river discharge is less and sufficient only for 1-unit operation, so that it will not affect power

Poring-1

Poring-2

1

10

100

1000

0.01 0.1 1 10 100

He (m)

Q (m3/sec)

Poring-1

Poring-2

Pelton

Turgo Impulse

Francis (H)

Francis (V)

Kaplan

Reverse Pump

Propeller (Siphone)

Crossflow

Submersible Pump

Tubular (S)

Propeller (Inline)

Source: NEF Small Hydropoewr Guidebook, 2005

Final Report

Preparatory Survey on North Sumatra Mini 4-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

generation. However, 1-unit × 10,000 kW will force to stop the operation during each inspection.

Accordingly, the number of unit and unit capacity is set at 2 units × 5,000 kW for both Poring-1 and

Poring-2.

(3) Efficiency of Turbine and Generator

The turbine efficiency is the product of the maximum turbine efficiency and the relative turbine efficiency

depending on the turbine manufacturer. Approximately, the maximum turbine efficiency is 88.6% and the

relative turbine efficiency is related to the discharge. The combined turbine efficiency is illustrated in the

following Figure 4.4.2.

The generator efficiency is the product of the maximum generator efficiency and the relative generator

efficiency. Approximately, the maximum generator efficiency is 97.0% based on the relation between

rotor pole number and installed capacity, and the relative generator efficiency is related to the load ratio.

The combined generator efficiency is illustrated in the following Figure 4.4.2.

Poring-1 Turbine and Generator Poring-2 Turbine and Generator

Source: JICA Survey Team

Figure 4.4.2 Efficiency of Turbine and Generator

4.5 PLANT DISCHARGE

Plant discharge for hydropower development includes maximum plant discharge and firm plant discharge.

The maximum plant discharge is the discharge for maximum output in the powerhouse and used for the

design of waterway, turbine, and generator. The firm plant discharge is the discharge available throughout

355 days, which is determined by the drought discharge (355-day dependable) minus water use and

maintenance discharge.

(1) Maintenance Discharge

The flow duration curve of the Poring River as described in Chapter 3.4 (Hydrology) is used to estimate

the available plant discharge. It is recommended to consider the minimum maintenance flow discharge of

the Poring River in order to maintain the existing river environment. In this project, the intake discharge

is set to satisfy the maintenance discharge and water use discharge by comprehensively considering

tributary inflows from the remaining basin area and outflow of excess discharge at Poring-1 Powerhouse.

60%

70%

80%

90%

100%

30% 40% 50% 60% 70% 80% 90% 100%110%

Eff

icie

ncy

Discharge Ratio, Q/Qmax

TurbineGeneratorCombined

Source: NEF Hydropower Guide Book

60%

70%

80%

90%

100%

30% 40% 50% 60% 70% 80% 90% 100%110%

Eff

icie

ncy

Discharge Ratio, Q/Qmax

TurbineGeneratorConbined

Source: NEF Hydropower Guide Book

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Preparatory Survey on North Sumatra Mini 4-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The maintenance discharge is the minimum discharge during drought season to conserve the natural

environment for fish, animals, and other flora and fauna1. In this study, the maintenance discharge is set at

0.35 m3/s per 100 km2, which is in reference to the natural environmental study. The maintenance

discharge of 0.35 m3/s per 100 km2 is generally applied as maintenance discharge of Japanese river

facilities.

The water use discharge is the existing discharge for irrigation and water supply. According to the site

reconnaissance, no particular activity such as irrigation intake, paddy fields, and crops was observed

between the intake weir and the powerhouse for both projects. Therefore, this water use discharge is not

applied in this study, which is in reference to the social environmental study.

Accordingly, the maintenance flow discharge requirement is calculated to be 0.31 m3/s for the 87.45 km2

catchment area of Poring-1.

(2) Plant Discharge

Determination of the maximum plant discharge is not specified by law and regulation, so that it is

normally determined by an optimization of the unit generation cost. Generally, the maximum plant

discharge is determined, based on the capacity factor (= average plant discharge/maximum plant

discharge), to be around 70%. This is assuming that the generated energy is difficult to evacuate in the

grid system. The optimization of maximum plant discharge is selected from 3-5 alternatives depending on

the capacity factor and compared with unit generation costs.

In this project more river discharge is available than the requirement of 10 MW, so that the installed

capacity is not determined by the maximum plant discharge, but the maximum plant discharge is

determined by the installed capacity of 10 MW under the limitation of the FIT program.

Accordingly, the maximum plant discharge is summarized in Table 4.5.1 below. The minimum plant

discharge for Francis type turbine is estimated at 40% of the maximum plant discharge.

Table 4.5.1 Plant Discharge and Installed Capacity of Poring-1 and Poring-2

Item Poring-1 Poring-2

Installed Capacity 10.0 MW 10.0 MW

Rated Effective Head 193.2 m 232.3 m

Maximum Plant Discharge 6.00 m3/s 5.00 m3/s

Minimum Plant Discharge 1.20 m3/s 1.00 m3/s

River Utilization Factor (Plant Factor) 69.8% (82.1%) 66.0% (89.6%) Source: JICA Survey Team

The plant discharge will cover the flow range of duration curve at each intake site as shown in the

following figures.

1 Guideline of River Maintenance Flow, Ministry of Land, Infrastructure, Transport and Tourism

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Preparatory Survey on North Sumatra Mini 4-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Figure 4.5.1 Plant Discharge for Poring-1

Figure 4.5.2 Plant Discharge for Poring-2

4.6 ANNUAL ENERGY

Power simulations are undertaken to estimate energy production using the daily discharge for the latest

ten years from January 2004 to December 2014 obtained through the low flow analysis. The basic

conditions and the simulation results are shown in the following Table 4.6.1.

Table 4.6.1 Annual Energy for Poring-1 and Poring-2

Item Poring-1 Mini Hydropower Poring-2 Mini Hydropower

Anual Energy Generation 69.1 GWh/yr 75.3 GWh/yr Source: JICA Survey Team

The following figures illustrate the average annual output and annual energy in the above simulation.

0

3

6

9

12

15

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Dis

char

ge (m

3 /se

c)

Probability

Plant Discharge

Mean Runoff m3/sec

Max. Plant Discharge m3/sec

Min. Plant Discharge m3/sec

7.10

6.00

1.20

Source: JICA Study Team

0

3

6

9

12

15

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Dis

char

ge (m

3/s

ec)

Probability

Plant Discharge

Mean Runoff m3/sec

Max. Plant Discharge m3/sec

Min. Plant Discharge m3/sec

7.39

5.00

1.00

Source: JICA Study Team

Final Report

Preparatory Survey on North Sumatra Mini 4-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 4.6.1 Dependable Output and Energy for Poring-1

Source: JICA Survey Team

Figure 4.6.2 Dependable Output and Energy for Poring-2

Annual energy generation was calculated based on the assumption of 10 MW installed capacity and

optimization of the layout, effective head, and maximum plant discharge obtained through the above

repeated calculations.

0

50

100

150

200

250

2,000

4,000

6,000

8,000

10,000

12,000

0% 20% 40% 60% 80% 100%

Dep

enda

ble

Ene

rgy

(MW

h)

Dep

enda

ble

Out

put

(kW

)

Probability

Generator Output (kW)

Turbine Output (kW)

Dependable Daily Energy (MWh)

0

50

100

150

200

250

2,000

4,000

6,000

8,000

10,000

12,000

0% 20% 40% 60% 80% 100%

Dep

enda

ble

Ene

rgy

(MW

h)

Dep

enda

ble

Out

put

(kW

)

Probability

Generator Output (kW)

Turbine Output (kW)

Dependable Daily Energy (MWh)

Final Report

Preparatory Survey on North Sumatra Mini 5-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 5 BASIC DESIGN

5.1 BASIC DESIGN OF CIVIL WORKS

5.1.1 PORING-1 INTAKE WEIR

(1) Site Conditions

The selected position of intake weir satisfies the following criteria:

The foundation should be a sound bedrock with little sediment deposit,

A relatively small excavation should reach the well consolidated layer suitable for foundation of the

structure when constructing on deep river deposit,

Scouring is not expected on the river banks and riverbed immediately downstream after the weir

construction,

Ease of river diversion and coffering works during construction,

Cross section can safely release the flood discharge despite future sedimentation, and

The intake weir is placed perpendicular to the river bank.

(2) Intake Weir Axis

The axis of the intake weir is selected as follows: 1) exposed granite foundation, 2) on a straight river

section rather than curved river section, 3) away from landslide areas on the right bank, and 4) allow

convenience of construction away from the waterfalls. Spillway for intake weir is set at 33.0 m according

to downstream river width. The design flood for Poring-1 Intake Weir is 100-year probable flood (Q=680

m3/s), so that the water depth is 6.15 m above the riverbed (EL. 645.65 m).

Below is the H-Q Curve at Poring-1 Intake Weir Site to estimate flood water level based on flood

discharge in the hydrological study and the results of river cross section survey by non-uniform flow

analysis.

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Source: JICA Survey Team

Figure 5.1.1 H-Q Curve at Poring-1 Intake Weir Site

The minimum height of the intake weir is constructed at the weir axis and the overflow crest elevation is

EL. 646.50 m as the full supply water level (FSL).

Source: JICA Survey Team

Figure 5.1.2 Location of Poring-1 Intake Weir Axis

Looking Downstream of Weir Axis Looking Upstream of Weir Axis Source: JICA Survey Team

Figure 5.1.3 Location of Poring-1 Intake Weir Site

100-yr FloodQ= 680 m3/s H= 6.15 m

0.0

2.0

4.0

6.0

8.0

0 100 200 300 400 500 600 700 800

Wat

er D

epth

(m

)

Discharge (m3/s)

Poring-1 Intake Site, Tentatively Assumed River H-Q Curve

Non-uniform Flow Analysisby River Cross Section SurveyRoughness coefficient: n=0.05

Weir Axis Weir Axis

Mouth of Waterfall

Collapsed Old Talus

Poring River

Intake Weir-1

Power Intake-1

Project Road to Intake-1 Sand Trap Basin-1

Headrace Channel-1

35m

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(3) Structure Type and Weir Height

The intake weir is a 7.0 m high non-gated concrete gravity structure to provide the full supply water level

at EL. 646.5 m. Weir shape will consider abrasion by falling gravel which downstream surface gradient of

1:0.2 is adopted, and upstream surface gradient has been set at 1:0.5 based on the stability analysis.

(4) Overflow Depth and Freeboard

The intake weir is 33.0 m wide crest to discharge 100-year flood of 680 m3/s. The flood water levels

are estimated at EL. 651.09 m for 100-year flood, which is 4.95 m above the crest elevation as shown in

the following formula. In addition, freeboard was calculated by using the slope of stream bed from the

following formula. Non-overflow section height has been set at 6.2 m (= 4.95 m + 1.25 m).

WeirofwidthSpillwayBmdepthOverflowhWhere

sm

mChBhQ

hBBgCQ

:1),(:3;

)/68068295.4)0.3377.195.471.0(

)5.0,6.0(,)77.171.0(

,23215

2

32/3

2/3313

2/3321

Source: ：Technical Criteria for River Works in Japan

Source: JICA Survey Team

Figure 5.1.4 Flood Discharge Rating Curve at Intake Weir

Table 5.1.1 Relationship of Slope of Stream Bed and Design Water Depth Slope of Stream Bed Freeboard/Design Depth

More than 1/10 0.50 1/10 to 1/30 0.40 1/30 to 1/50 0.30 1/50 to 1/70 0.25

Source: Technical Criteria for River Works in Japan

50/1:

)70.652.25.145,.651.(25.124.195.425.0

bedstreamofSlopeWhere

mELELboadFree

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(5) Location and Height of Counter Dam

Intake weir is concrete gravity dam type that does not have a spillway gate. The intake weir is designed to

be placed on the fresh granite foundation rock. The apron for overflow discharge is not provided because

there is low risk for erosion of riverbed. Drop will occur in the river channel by the construction of intake

weir. The consultant proposed a stilling basin between the main dam and counter dam. Counter dam

height and installation position are planned using the following formula:

)95.4(:3

)0.7(:1;

239.23~9.17)95.40.7(0.2~5.1

)31(0.2~5.1

mdepthOverflowh

mheightWeirHWhere

m

hHL

m

ElfoundationdamMain

ElspillwaydamCounterH

mHHWhere

mHH

75.150.63925.641

)(

)(:2

)0.7(1;

75.1~33.24/1~3/12

Source: ：Technical Criteria for River Works in Japan

Source: JICA Survey Team

Figure 5.1.5 Location of Counter Dam

(6) Stability Analysis of Weir

The section is determined so as to satisfy the following conditions:

1) no overturning, 2) no sliding, and 3) no settlement

Stability calculations are calculated for the following four locations:

- Spillway section and non-overflow section of main dam.

- Spillway section and non-overflow section of counter dam.

The dimensions of the typical section are determined to satisfy the above requirement.

Counter-dam spillway

Main-dam foundation

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Source: JICA Survey Team

Figure 5.1.6 Front View of Main Dam

Intake Weir

PowerIntake

(7) Environmental Discharge Facilities

Environmental discharge facilities are

installed in the purpose of maintaining the

normal function of the river flowing water.

Installation position of outlet valve must set

to always can flow elevation and location.

Environmental discharge will be set

Q=0.31m3/s.

Facilities are set the diameter φ300 of pipe

and discharge adjustable valve.

(8) Sand Flushing Way

The reservoir sedimentation of intake weir

will be relatively large and it will easily

get full in a short period because of rapid

river flow. Therefore, scouring way is

required to maintain the inflow discharge

and to prevent sedimentation from flowing

into the waterway.

The scouring way is located in front of the

intake on the left bank with 2.0 m width

and 2.0 m height to discharge the

sedimentation by opening the gate

particularly at the end of the flood flow.

The invert elevation of the scouring way is

designed to be lower than the invert elevation of the intake by more than 1.0 m.

(9) Power Intake

The site of power intake is selected so that

the design discharge can be taken from the

river without being affected by

sedimentation behind the weir, and it is

free from damage caused by flood flow

and drift wood. The intake is aligned at

right angle or at a slightly lesser angle to

the river.

The floor level of Poring-1 Power Intake is

set at EL. 644.2 m, which is 1.5 m above

Source: JICA Survey Team

Figure 5.1.7 Plan of Intake -1

Source: JICA Survey Team

Figure 5.1.8 Profile of Intake -1 Portal

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Hydropower Project (PPP Infrastructure Project)

that of the scouring way. The intake is designed to control velocities smaller than 0.5 m/s when the

maximum plant discharge is taken. Two sets of intake trashracks with dimensions of 3.0 m (width) and

2.0 m (height) are provided to avoid floating debris from entering the waterway. The intake gate deck is

placed at EL. 652.7 m with a freeboard of 1.0 m above the flood water level during a 100-year flood.

Source: JICA Survey Team

Figure 5.1.9 Profile of Poring-1 Power Intake and Sand Trap Basin

One of the serious risks to be considered for the design of a run-of-river scheme is excessive inflow into

the waterway during flooding, taking into account the difficulty for timely operation of the intake gate,

particularly for rivers like the Poring River where a peak flood rises quickly. An overflow depth is

estimated by low flow analysis for maximum discharge on the weir crest, and therefore, two protective

walls at the entrance and the intake gate are essential to block harmful discharge as well as floating debris

from entering the channel. Closing of the intake gate is assumed based on river discharge of 60 m3/s.

Headrace channel will be overflow to the road side which exceeding the discharge capacity of headrace

channel. Even if gate was not closed that Impact to the facilities would be small.

In addition, sand trap basin is planned in two-way lane for future maintenance. Maximum inflow

discharge to the intake from one-way operation will be Q=3.5 m3/s.

(10) Sand Trap Basin

River water contains a certain volume of suspended sediments. During flood, sediment concentration

increases substantially. In run-of-river plants, suspended sediments are deposited in the waterway, and

choke its sectional area. It is also the cause of erosion of the penstocks and turbines. To settle and flush

this sediment, it is necessary to install a sand trap basin close to the intake. The sand trap basin having

dimensions of 3.0 m (width) × 2 (lane) × 4.7 m (height) on average × 28.5 m (length) is provided between

the power intake and the headrace channel. The sand trap basin plan were considered at the sediment

depth of 1m.

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River Discharge in Dry Season River Discharge in Flood Season Source: JICA Survey Team

Figure 5.1.10 Suspended Sediments of Poring River

(11) Side Spillway

An 18.0 m long side spillway is provided with the sand trap basin to release excessive discharge. It will

be available for flood control with additional second spillway (B=13.0m) for the discharge.

(12) Emergency Closing Gate System

The gate of the intake is planned to be closed by detection system using optical fiber sensor cable for the

following measures:

- Slope collapse of the headrace channel (including penstock)

- Damage of the waterway due to natural disasters such as debris flow and falling rocks

Optical fiber cable shall be installed between Intake-1 and Powerhouse-1. Light pulse is sent to the cable

to detect strain and disconnection of the sensor cable.

5.1.2 PORING-1 HEADRACE CHANNEL

(1) Site Conditions

The headrace channel is designed to be a non-pressure

type waterway. In terms of hydraulics, the non-pressure

waterway is an open channel with free water surface.

Poring-1 Headrace passes over flat terrain to connect

Poring-1 Sand Trap Basin and Poring-1 Head Tank by

reinforced concrete (RC) channel and box culverts.

The alignment of the headrace channel is set to avoid

landslide locations, embankments, and large excavated

slopes.

The slope is to be excavated steeply to prevent the slopes

from being eroded by rainfall discharge. The channel is aligned on the relatively flat terrain of rubber

Source: JICA Survey Team

Site Condition of Poring-1 Headrace

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plantation, but partially goes through steep cliffs.

Proper slope drainage is important for open channel for future slope stability. The maintenance road and

drain ditch are provided along the channel, and crossing drainage pipe below the channel is also prepared.

Furthermore, the headrace channel passes along several local rivers and river crossing structures are

prepared at these locations.

(2) Typical Section of Headrace

Typical sections of alternative cases (wet masonry, RC concrete channel, and box culvert) were planned

for comparison.

Furthermore, applying a steeper longitudinal profile enables reduction in the concrete volume. Open

headrace channels are at risk of closure/blockage due to landslides and collapses which will result in

halting power generation. Therefore, in order to avoid this risk, covered concrete culvert may be used as

an alternative.

Therefore, headrace channel is planned not as a masonry channel but as a combination of open concrete

channel and box culvert in consideration of the stability of future excavated slope.

The criteria for selecting box culvert are excavation height of more than 6.0 m and original slope gradient

to be steeper than 30 degrees. Also, at the section of steep slopes, the possibility of falling rocks and

landslides, rain flow from the slopes, river crossings, and village crossings are considered.

Box Culvert Section

Open Channel Section Source: JICA Survey Team

Figure 5.1.11 Typical Section of Poring-1 Headrace

(3) Longitudinal Gradient of Headrace

The size of headrace channel is determined by the flow velocity which is dominated by the longitudinal

gradient. In general, steeper longitudinal gradient leads to smaller cross sections but more head loss so

that it is not always economical. Conversely, gentler longitudinal gradient requires greater flow area as

well as the risk of more sediment settlement due to smaller flow velocities.

Within these limitations, the optimum cross section to transport the maximum plant discharge is

compared considering the cross section, slope gradient, energy generation, construction cost of headrace

channel, and construction method. Headrace channel is designed so as to satisfy the following conditions.

Final Report

Preparatory Survey on North Sumatra Mini 5-9 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Headrace channel gradient adopted is i = 1/500 according to the comparison study.

(4) Typical section and freeboard

Typical section to ensure the ability to safely flow down the maximum plant discharge are used.

Optimization of headrace channel was performed by having the lowest excavation amount. The loss

calculation of the curved portion will be used for the headrcae channel curvature radius of R=4.0 m

(R/D>2). Non-uniform flow calculation provides the starting water level in the head tank.

Table 5.1.2 Non-uniform Flow Calculation Result of Headrace Channel-1

[Design Condition] Q=6.0 m3/s, i=1/500, n=0.014 Shape: 1.7 m (base) x 2.20 m (height)

Calculation Method Water Depth (m) Uniform flow 1.63 Non-uniform flow 1.68 Non-uniform flow + turning loss

2.05

The freeboard of 15 cm, even when considering

the loss of the curved portion, will safely ensure

the allowable discharge.

Source: JICA Survey Team

(5) River Crossing Structures

The headrace channels are designed to cross the local rivers at five positions for Poring-1 project area and

the crossing structures are designed to be box culverts with concrete retaining walls downstream of the

local rivers. Gabion mattress will be installed in the inlet and outlet of crossings. The surface of the river

crossing is covered with concrete pavement and the river discharges are maintained with small ditches.

Design discharge was determined by the rational formula to calculate the catchment area of the crossing

section of river. Target discharge of the facilities will be set by the 10-year probability of rainfall scale.

Edge of cross-section for the river crossing facilities are estimated from existing river width. The position

of critical depth will be occurred by the narrowed area. Cross section shape of the river crossing facilities

assumes that the critical depth occurs at the end of the crossing structure to determine the width and

height for a given discharge.

Final Report

Preparatory Survey on North Sumatra Mini 5-10 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.12 Locations of River Crossings for Poring-1

Source: JICA Survey Team

Figure 5.1.13 Typical Section of River Crossings

5.1.3 PORING-1 HEAD TANK

(1) Site Conditions

Poring-1 Head Tank is located at the top of the penstock

which is aligned perpendicular to the slope along the ridge

behind the powerhouse. The headrace channel is extended

downward as much as possible to reduce the length of the

penstock.

The head tank is located on a 30 degree steep slope, and the

surface is covered by thick weathered talus deposit.

However, the geological condition at a depth lower than 4.5

m shows an N-value of more than 50.

Accordingly, the head tank is designed to be constructed in

this area. The construction yard for the head tank will be 15 m (width) × 30 m (length), so that the large

excavated slope is to be protected from landslide and collapse.

Source: JICA Survey Team

Site Condition of Poring-1 Head Tank

Poring-1 Poring-2ST.0+247.76 ST.0+221.35ST.0+ 999.36 ST.1+267.86ST.1+625.70 ST.1+ 486.58ST.2+212.57ST.2+395.420

Final Report

Preparatory Survey on North Sumatra Mini 5-11 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Minimization of Head Tank

The head tank functions to balance the discharges between the headrace and penstock at sudden load

change at the powerhouse, e.g., to supply water at sudden load increment and to spill out the excess water

during emergency stop. Also, it functions to trap and discharge the inflow sediment before the turbines to

prevent damage.

The capacity of the head tank is normally designed to store 2-3 minutes volume of maximum plant

discharge but this is on the assumption of no inflow from the headrace. The recent trend of design is

minimizing the storage volume of the head tank assuming inflow from the headrace.

(3) Controlling Water Level

Head tank water level varies depending on operation (controlling discharge into the turbines by

adjusting the opening of guide vane depending on the head tank water level),

Required water surface area to prevent vibration of water level: A 10Qmax

Required water volume to supply discharge at the emergency water level: V 11Qmax

Overflow discharge at emergency circuit: providing spillway for safely releasing the maximum

design discharge through side spillway without increasing water level when operation is suddenly

stopped because of the emergency circuit such as transmission system accident,

Gradual transition between headrace channel and head tank so as not to cause whirl or deviation

flow,

Water depth at the inlet of penstock is twice greater than the penstock inner diameter in order to,

Not necessary to provide a gate in the head tank

(4) Sand Trap

Average flow velocity in the head tank: smaller than 0.3 m/s.

Required length to settle the suspended load: (L)：L u, where, vg: allowable settlement

velocity of sand particle (larger than 0.5-1.0 mm) which is targeted to settle (vg = 0.1 m/s), h:

average water depth of head tank, u: average velocity of head tank

Transition section at the inlet of head tank is designed to have enlarged angle smaller than 40

degrees so as not to reduce settlement function by drift or deviation of flow, otherwise providing

guide wall,

Invert slope of head tank is 1:10 for flushing the sediment same as sand trap basin,

Providing sand flush gate and channel

(5) Structural Outline

The head tank having dimensions of 6.0 m (width) × 3.5 m (height) on average × 25.4 m (length) is

provided between the waterway and the steel penstock.

Final Report

Preparatory Survey on North Sumatra Mini 5-12 Nippon Koei Co., Ltd.

Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.14 Longitudinal Profile of Poring-1 Head Tank

(6) Target Water Levels

Power operation is undertaken by monitoring the water level in the head tank to select an appropriate

operation mode: i) two-unit operation, ii) one-unit operation, or iii) suspension of operation. The head

tank is designed to have sufficient supply volume to allow reasonable period required for shifting the

operation modes by the following operation criteria:

Table 5.1.3 Target Water Levels for Poring-1 Head Tank

Design Condition 2-unit Rated

Operation

1-unit Rated

Operation

1-unit Minimum

Operation

Max. plant discharge for 2-unit operation 6.0 m3/s 3.0 m

3/s 1.2 m

3/s

Inside water surface area of head tank 131.1 m2 ( > 10 Q = 60 m

2)

Effective water volume of head tank 458.9 m3 ( >11 Q = 66 m

3)

Formation height of waterway EL. 639.27 m

Uniform depth at EP of waterway 1.63 m 0.94 m 0.46 m

Water level at EP of waterway EL. 640.90 m EL. 640.21 m EL. 639.73 m

Crest of side spillway (full supply level) EL. 641.00 m

Minimum operation level EL. 640.20 m EL. 639.70 m EL. 639.70 m

Water level for emergency closure EL. 639.70 m EL. 639.20 m

Minimum water level of head tank --- EL. 638.70 m Source: JICA Survey Team

(7) Side Spillway

A side spillway with a crest length of 12.0 m is provided for the case when the power operation is

suspended, and is designed to release the maximum plant discharge of 6.0 m3/s. The overflow discharge

flows into an open channel beside the head tank and connects to the spillway pipe along the penstock.

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Preparatory Survey on North Sumatra Mini 5-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.1.4 PORING-1 PENSTOCK

(1) Site Conditions

Penstock is designed along the ridge line of the slope

between the head tank and powerhouse to avoid the route

from crossing over the local stream to reduce the damage

and erosion of penstock foundation by flood flow, land

sliding, and rolling stones.

The ridge line is excavated along the penstock so as to

locate the steel pipe on the ground by concrete or masonry

saddle supports.

Seven anchor blocks are designed and concrete saddles

with an interval of 6.0 m will be provided to support the

penstock between anchor blocks. The excavated sides and

bottom surfaces are protected by wet stone masonry with drainage pipes and ditches for surface drainage.

The following Figure 5.1.15 shows the plan and profile as well as typical cross section.

Source: JICA Survey Team

Figure 5.1.15 Plan and Profile of Poring-1 Penstock

Source: JICA Survey Team

Site Condition of Poring-1 Penstock

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Preparatory Survey on North Sumatra Mini 5-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The alignment of Poring-1 Penstock is along the relatively narrow ridge line which is 430.9 m long and

194.4 m high. The profile is 27.3 degrees on average and the maximum angle is 41.2 degrees at the

section behind the powerhouse.

At the lower horizontal section, shortly after the last bend, the penstock connects to a Y-branch pipe, then

it will be divided into two lanes and finally connects to each unit.

(2) Optimum Penstock Diameter

The penstock diameter is determined by the flow velocity and it is normally set at 2.0-4.0 m/sec (NEF

Guide Book for Small Hydropower). The high head hydropower plants such as this Project tend to be

more advantage of cost comparison with smaller diameter and larger head loss to some extent.

Therefore, the average flow velocity is set at around 4.0 m/sec, which is widely applied in small

hydropower projects.

(3) Water Hammer and Closing Time

The closure time of turbine and generator is determined by the comparison of steel weight of penstock

and flywheel of turbine and generator. The longer the closure time, the smaller the penstock weight due to

the smaller pressure rise in the penstock, but it requires heavier weight of flywheel of turbine and

generator. Accordingly, the closure time is set at 5 s.

Source: JICA Survey Team

Figure 5.1.16 Optimum Closing Time of Turbine and Generator

(4) Optimum Thickness of Penstock

Accordingly, the dimensions of Poring-1 Penstock are summarized in the following Table 5.1.4.

Furthermore, the required thickness of steel penstock is calculated from internal pressure including static

head and water hammer, and from external pressure at empty condition. It is noted that the water hammer

analysis applies the Allievi Formula.

1.76

1.78

1.80

1.82

1.84

1.86

2.0 3.0 4.0 5.0 6.0 7.0 8.0

Pen

stoc

k +

Gen

erat

or

Cos

t (U

SD M

il.)

Closing Time (sec.)

Assumption: Unit Rate of Steel Penstock=4,000 USD/tonGenerator=1.084 M USD/2-unit for T=5.0 sec.

Final Report

Preparatory Survey on North Sumatra Mini 5-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 5.1.4 Water Hammer Analysis and Penstock Steel Thickness for Poring-1

Design Condition:

Discharge : Qmax = 6.0 m3/s

Static head : H0 = 199.00 m

Closing time of guide vane T = 5.0 s

Allievi Formula for water hammer:

.

√1.25 n . %

θ 5.463 ρ 1.013 n 0.185

No. Length (m)

Diameter (m)

Wave Velocity

(m/s)

Discharge Velocity

(m/s)

Coefficient of Allievi

Static Head (m)

t for int. pressure

(mm)

t for ext. pressure

(mm)

Thicknesst

(mm) 1 4.00 1.350 789 4.192 0.850 4.6 1.9 6.0 6 2 93.67 1.350 789 4.192 0.850 53.0 5.6 6.0 6 3 136.79 1.350 925 4.192 0.996 98.0 9.1 6.0 10 4 72.75 1.350 972 4.192 1.046 129.0 11.5 6.0 12 5 105.72 1.350 1,068 4.192 1.150 199.0 17.5 6.0 18 6 4.00 1.350 1,068 4.192 1.150 199.0 17.5 6.0 18 7 12.00 1.000 1,063 3.820 1.043 199.0 12.9 5.0 13 8 2.70 1.000 1,063 3.820 1.043 199.0 12.9 5.0 13

Total or Average

430.88 (=L0)

1.338 943 (=α)

4.179 (=V0)

1.012 (=ρ)

--- --- --- 11.6

Source: JICA Survey Team

Consequently, a closing time of 5.0 s, maximum water head of 247.3 m, and maximum pressure rise of

24.3% are applied in the design of the Poring-1 Penstock.

(5) Y-Branch and Branch Pipes

Penstock is divided into two lanes to connect hydraulic turbines at the lower horizontal section in front of

the powerhouse. Y-branch is applied to be open to 60 degrees for 12 m distance from the turbines and the

branch pipes are 1.0 m in diameter.

(6) Saddle Support

Type of intermediate support is divided into two types, i.e.: saddle support for relatively smaller diameter

penstock and ring girder support for relatively larger diameter penstock. Since the construction cost of saddle

support is generally much smaller than that of ring girder support, the saddle support is selected in this project.

(7) Anchor Blocks

At the position of no bends, the penstock is supported by concrete anchor blocks. Intermediate positions

between anchor blocks are supported by concrete saddles against vertical load. The overflow spillway

pipe is also aligned parallel to the penstock, so that the supports of the anchor blocks and saddles will

utilize the ones provided for the penstock.

The stability conditions (overturning, sliding, and bearing stabilities) are to be confirmed against each

combination of dead load, combined water pressure, deflection due to temperature change, and seismic

load.

The dimensions of anchor blocks are determined to satisfy the above requirement.

Final Report

Preparatory Survey on North Sumatra Mini 5-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.1.5 PORING-1 HEAD TANK SPILLWAY

(1) Type of Pipe Spillway

Head tank spillway is provided to discharge excess water to the river through open channel, closed

conduit, or pipeline (steel pipe, RC pipe, FRP). The overflow spillway is normally designed on steep

slope along the steel penstock with the same head and discharge so that it requires the facility with safety

discharge.

The discharge from the head tank spillway depends on the turbine emergency stop. Therefore, it is

prohibited to discharge into the recession river section between intake and powerhouse without a flood

warning system because it may be fatal to human life or to just discharge at the downstream of tailrace

outlet.

It is possible to shorten the length of head tank spillway when a local stream is available to discharge the

water. However, careful attention is required not to cause erosion of the riverbed. Moreover, in case there

is no exposed rock in the local stream, it will be higher risk for erosion, and it may cause large-scale

landslide. As there are no local streams with the required geological conditions in the area of the head

tank, the pipe spillway is designed parallel to the penstock in this project.

Particularly for Poring-1, the pipe spillway is used as a bypass waterway for Poring-2 due to elimination

of Poring-2 Intake Weir.

Source: Cianten Small Hydropower Project in Indonesia

Example of Spillway Releasing to Local StreamSource: NEF “Design Manual of Simplified Generation System”

Example of Pipe Spillway Figure 5.1.17 Comparison of Pipe Spillway

After the pipe spillway at the head tank, the excess water is discharged by side channel to the inlet of pipe

spillway. Then, an overflow weir is provided at the inlet of pipe spillway to provide smooth discharge.

The flow inside the pipe spillway is supercritical flow with high velocity so that air pipes are designed at

every bend of the pipe spillway.

An energy dissipater is also designed at the end of the pipe spillway below the erection bay of the

powerhouse because the design discharge with high head will be released. Finally, the excess discharge

connects to Poring-1 Tailrace.

Final Report

Preparatory Survey on North Sumatra Mini 5-17 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Diameter of Pipe Spillway

The flow inside the pipe spillway is supercritical flow with high velocity. It is noted to reduce curves of

pipe so as to allow smooth discharge. The higher discharge velocity allows the pipe to have a smaller

diameter and lower construction cost. However, the reduction of pipe diameter is not applied because

transition pipe is expensive and difficult to set. To maintain less than 50% of flow area ratio (=flow

area/pipe area) for safe discharge condition as shown in the following Table 5.1.5, the pipe diameter

should be 0.95 m.

Table 5.1.5 Non-Uniform Flow Analysis for Overflow Spillway Pipe for Poring-1

Source: JICA Survey Team

(3) Energy Dissipater

An energy dissipater for killing the hydraulic energy is

provided at the end of the pipe spillway for safe

release of spillout discharge.

The types of energy dissipater are 1) impact type, 2)

shaft type, and 3) hydraulic jump type. In case

Q＋P 25 Q 15m /s, P 20MW , an impact

type energy dissipater is within the applicable range.

Typical dimensions of impact type energy dissipater are shown in Figure 5.1.20 below. The width

requirement is about 4.5 m for 5~6 m3/s discharge, so that the energy dissipater will be placed below the

Length Depth Area Velocity V head Wet R Invert EL. Slope Ratio Frude

(m) h (m) A (m2) V (m/s) V^2/2g (m) P (m) R (m) (m) θ deg <50% Fr>1

Sta.0 0.0 0.200 0.213 28.19 40.6 1.5 0.1 638.125

Sta.5 4.7 0.220 0.224 26.73 36.5 1.5 0.2 635.725 27.25 31.7% 18.2

Sta.99 94.0 0.406 0.321 18.68 17.8 1.5 0.2 587.325 27.25 45.3% 9.4

Sta.236 137.5 0.457 0.346 17.37 15.4 1.5 0.2 542.325 18.13 48.7% 8.2

Sta.309 72.5 0.378 0.307 19.55 19.5 1.5 0.2 511.325 23.15 43.3% 10.2

Sta.417 108.7 0.285 0.260 23.07 27.2 1.5 0.2 438.975 33.66 36.7% 13.8

Sta.431 13.8 0.385 0.311 19.30 19.0 1.5 0.2 438.975 0.00 43.9% 9.9

Station

Source: http://www.kanapipeline.com/images/energy-dissipator.html

Figure 5.1.19 An Example of Impact Type Energy Dissipater

Source: T. Inamatsu, Standard Form Selection of Headtank Spillway and Energy Killer in Water Power Plant, 1983

Figure 5.1.18 Type Selection Chart of Energy Dissipater

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Preparatory Survey on North Sumatra Mini 5-18 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Photo taken by the JICA Survey Team

Site Conditions of Poring-1 Powerhouse

concrete slab at the erection bay of the powerhouse.

Source: Equations of Hydraulic Engineering, JSCE

Figure 5.1.20 Typical Dimensions of Impact Type Energy Dissipater

5.1.6 PORING-1 POWERHOUSE

(1) Site Conditions

The position of powerhouse was selected

as shown in the alternative layout study.

Poring-1 Powerhouse is, based on the

penstock alignment on the ridge line,

located on a relatively gentle slope at the

foot of the penstock slope.

The geological investigation revealed

that rock foundation (fresh granite) will

be exposed after 5.0 m. The concrete slab

of powerhouse will be constructed on this rock surface. The penstock slope is stable against sliding

despite being covered with talus deposit and lying 40 degrees due to angular gravel content in the talus.

However, the design is limited to the excavation of the slope toe.

Access to Poring-1 Powerhouse is along the Poring-2 Headrace Channel from Siantar Naipospos Village.

Also, the temporary construction road will be constructed by widening the existing footpath during the

construction.

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Preparatory Survey on North Sumatra Mini 5-19 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Setting Levels

The design flood for Poring-1 Powerhouse is 100-year probable flood (Q = 710 m3/s), so that the water

depth is 3.29 m above the riverbed (EL. 441.50 m).

Below is the H-Q Curve at Powerhouse-1 Site by non-uniform flow analysis.

Source: JICA Survey Team

Figure 5.1.21 H-Q Curve at Powerhouse-1 Site

The powerhouse yard elevation, EL. 442.50 m, is determined from the 100-year probable flood water

level of the Poring River with a 1.0 m freeboard based on the H-Q curve. The slab elevation is 200 mm

higher than the yard elevation to prevent rainfall discharge into the powerhouse.

Turbine center level as well as tailwater level and penstock center level are determined as explained in the

electro-mechanical design.

Table 5.1.6 Poring-1 Powerhouse Setting Level

Turbine Center Elevation EL. 443.40 m (≤ TWL + Hs*)

Surface Level of Powerhouse Concrete EL. 442.70 m (Yard Level + 0.20 m)

Powerhouse Yard Level (Yard EL) EL. 442.50 m (= FWL + freeboard (= 1.00 m)

Penstock Center Elevation (PCL) EL. 442.00 m (= Turbine Center - A*)

Tailwater Level (TWL) EL. 442.00 m (=FWL + 0.50 m)

Flood Water Level (FWL) (100-year Probable Flood) EL. 441.50 m (from H-Q Curve)

Note: Hs* and A* are explained in the design of the electro-mechanical equipment. Source: JICA Survey Team

(3) Superstructure

The superstructure of the Poring-1 Powerhouse shall incorporate two units of turbine and generator,

erection bay, and control room for operation with dimensions of 10.8 m (width) × 38.0 m (length) × 9.0 m

(height).

The superstructure of the powerhouse for ceiling and overhead crane is designed to be a steel frame

structure. The capacity of overhead crane is 20 ton and crane girder is provided.

The plan and profile of Poring-1 Powerhouse are shown below.

100-yr FloodQ= 710 m3/s H= 3.29 m

0.0

1.0

2.0

3.0

4.0

0 100 200 300 400 500 600 700 800

Wat

er D

epth

(m

)

Discharge (m3/s)

Poring-1 Powerhouse Site, Tentatively Assumed River H-Q Curve

Non-uniform Flow Analysisby River Cross Section SurveyRoughness coefficient: n=0.05

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Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.22 Plan of Poring-1 Powerhouse

Source: JICA Survey Team

Figure 5.1.23 Profile of Poring-1 Powerhouse

(4) Powerhouse Yard

Powerhouse yard is a space to accommodate the powerhouse building and tailrace culvert as well as

auxiliary facilities such as main transformer, emergency diesel, and transmission line equipment.

Powerhouse yard with dimensions of 50 m × 20 m requires relatively large excavation at the foot of the

steep slope of the penstock. To reduce the excavation volume, excavation with slope of 1:0.5 and covered

with protection is provided. The protection work is designed to be reinforced concrete frame.

(5) Type of Turbine and Generator

As described in the previous chapter, hydraulic turbine is 2 units × 5,000 kW and generator is 2 units ×

5,380 kVA.

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5.1.7 PORING-2 POWER INTAKE

The tailrace of Poring-1 Powerhouse and Poring-2 Headrace are directly connected without discharging

back to the Poring River so that the construction of Poring-2 Intake Weir was cancelled. The water level

of the draft pond varies depending on the plant discharge, but it is important to keep the water level

higher to prevent air from entering into the draft tube. To control the water level, an overflow weir is

designed at the tailrace.

The water level of the tailrace pond is determined by the turbine discharges. To prevent air from entering

into the draft tube at the minimum plant discharge, the overflow weir is designed at the end of the tailrace.

The velocity of tailrace discharge is designed to be smaller than 0.5 m/s by increasing the cross sectional

area to reduce water surface fluctuation and head loss.

When the Poring-2 is under stop operation, the plant discharge will be released back to the Poring River

via tailrace side spillway, having a 14 m wide crest, by closing the intake gate of Poring-2 Power Intake.

The power intake is designed to be equipped with one intake gate downstream of the side spillway.

Source: JICA Survey Team

Figure 5.1.24 Longitudinal Profile between Poring-1 Tailrace and Poring-2 Power Intake

EL.441.60 m

Intake Gate

TWL 442.00 mSide Spillway

Overflow Crest 441.00 m Bottom EL. 440.09 m

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5.1.8 PORING-2 HEADRACE

(1) Site Conditions

The headrace channel is designed to be a non-pressure type

waterway. In terms of hydraulics, the non-pressure waterway

is an open channel with free water surface.

Poring-2 Headrace passes over flat terrain to connect

Poring-2 Intake and Poring-2 Head Tank by RC channel and

box culvert.

The alignment of Poring-2 Headrace is set to avoid landslide

locations, embankments, and large excavated slopes.

The slope is to be excavated steeply to prevent the slopes

from being eroded by rainfall discharge and the road will be

the space to stop local collapse.

Headrace is designed to go through sparse rubber plantation on the rather gentle left bank. On the way,

the headrace crosses the existing village (Siantar Naipospos Village) and the existing village road. The

houses are scattered on the slope. Therefore, the project will be required to pay maximum consideration

to avoid the resettlement of village people.

Proper slope drainage is important for open channel for future slope stability. The maintenance road and

drain ditch are provided along the channel, and crossing drainage pipe below the channel is also prepared.

Furthermore, the headrace channel passes several local rivers; thus, river crossing structures are prepared

at these locations.

(2) Typical Section of Headrace

Similar design concepts for the selection of typical section for Poring-1 Headrace have been applied for

Poring-2. Therefore, Poring-2 Headrace is planned not as a masonry channel but as a combination of open

concrete channel and box culvert in consideration of the stability of the future excavated slope.

Box Culvert Section

Open Channel Section

Source: JICA Survey Team

Figure 5.1.25 Typical Section of Poring-2 Headrace

Source: JICA Survey Team

Site Condition of Poring-2 Headrace

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(3) Longitudinal Gradient of Headrace

Similar design concepts for the determination of longitudinal gradient for Poring-1 Headrace have been

applied for Poring-2. Headrace channel is designed so as to satisfy the conditions at the maximum plant

discharge of Q=5.0 m3/s. Accordingly, the longitudinal gradient of 1/500 was the most economical and

selected.

(4) Typical section and freeboard

Typical section to ensure the ability to safely flow down the maximum plant discharge are used.

Optimization of headrace channel was performed by having the lowest excavation amount. The loss

calculation of the curved portion will be used for the headrace channel curvature radius of R=4.0 m

(R/D>2). The result of the non-uniform flow calculation for the given starting water level in the head tank

is shown in Table 5.1.7 below.

Table 5.1.7 Non-uniform Flow Calculation Result of Headrace Channel-2 [Design Condition] Q=5.0 m3/s, i=1/500, n=0.014 Shape: 1.6 m (base) x 2.15 m (height)

Calculation Method Water Depth (m) Uniform flow 1.51 Non-uniform flow 1.55 Non-uniform flow + turning loss

1.74

The freeboard of 41 cm, even when considering

the loss of the curved portion, will safely ensure

the allowable discharge.

Source: JICA Survey Team

(5) Crossing of the

Village

Poring-2 Headrace shall be

laid out to avoid crossing the

villages and designed to

provide 1.0 m wide walkway

along the channel during the

construction. Also, staircases

will be prepared at the side

of the headrace channel to

ensure the trafficability for

the villagers.

Source: JICA Survey Team

Figure 5.1.26 Layout of Headrace Channel Crossing the Village

Final Report

Preparatory Survey on North Sumatra Mini 5-24 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.27 Typical Section of Village Crossing

(6) River Crossing

The headrace channels are designed to cross the local rivers at three positions for Poring-2 and the

crossing structures are designed to be box culverts with concrete retaining walls downstream of the local

rivers. Gabion mattress will be installed in the inlet and outlet of crossings. The surface of the river

crossing is covered with concrete pavement and the river discharges are maintained with small ditches.

Design discharge was determined by rational formula to calculate the catchment area of the crossing

section of the river. Target discharge of the facilities will be set by the 10-year probability of rainfall scale.

Edge of cross-section for the river crossing facilities are estimated from existing river width. The position

of critical depth will be occurred by the narrowed area. Cross section shape of the river crossing facilities

assumes that the critical depth occurs at the end of the crossing structure to determine the width and

height for a given discharge.

Source: JICA Survey Team

Figure 5.1.28 Locations of River Crossings

Poring-1 Poring-2ST.0+247.76 ST.0+221.35ST.0+ 999.36 ST.1+267.86ST.1+625.70 ST.1+ 486.58ST.2+212.57ST.2+395.420

Final Report

Preparatory Survey on North Sumatra Mini 5-25 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.29 Typical Section of River Crossings

5.1.9 PORING-2 HEAD TANK

(1) Site Conditions

Poring-2 Head Tank is located at the top of the penstock which

is aligned perpendicular to the slope along the ridge behind the

powerhouse. The headrace channel is extended downward as

much as possible to reduce the length of the penstock.

The existing slope of the head tank is around 25 degrees steep,

and the surface is covered by thick weathered talus deposit.

The surface geological conditions at lower than 6.0 m deep

show an N-value of more than 20.

Poring-2 Head Tank is designed to be constructed in this area by excavating the layer with N-value of less

than 20. Furthermore, precast concrete piles will be provided where required.

The construction yard for the head tank will be 15 m (width) × 30 m (length), so that the large excavated

slope is to be protected from landslide and collapse.

Similar design concepts for Poring-1 Head Tank have been applied for Poring-2 Head Tank.

Minimization of Head Tank

Controlling Water Level

Sand Trap

(2) Structural Outline

Poring-2 Head Tank, having dimensions of 5.0 m (width) × 3.5 m (height) on average × 24.5 m (length),

is provided with the above functions as illustrated below.

Source: JICA Survey Team

Site Conditions of Poring-2 Head Tank

Final Report

Preparatory Survey on North Sumatra Mini 5-26 Nippon Koei Co., Ltd.

Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 5.1.30 Longitudinal Profile of Poring-2 Head Tank

(3) Target Water Levels

Power operation is undertaken by monitoring the water level in the head tank to select an appropriate

operation mode: i) two-unit operation, ii) one-unit operation, or iii) suspension of operation. The head

tank is designed to have sufficient supply volume to allow reasonable period required for shifting the

operation modes through the following operation manners:

Table 5.1.8 Target Water Levels in Poring-2 Head Tank

Design Condition 2-unit Rated

Operation

1-unit Rated

Operation

1-unit Minimum

Operation

Max. plant discharge for 2-unit operation 5.0 m3/s 2.5 m

3/s 1.0 m

3/s

Inside water surface area of head tank 131.1 m2 ( > 10 Q = 50 m

2)

Effective water volume of head tank 458.9 m3 ( >11 Q = 55 m

3)

Formation height of waterway EL. 434.85 m

Uniform depth at EP of waterway 1.51 m 0.88 m 0.45 m

Water level at EP of waterway EL. 436.36 m EL. 435.73 m EL. 435.30 m

Crest of side spillway (full supply level) EL. 436.40 m

Minimum operation level EL. 435.80 m EL. 434.80 m EL. 434.80 m

Water level for emergency closure EL. 435.30 m EL. 434.80 m

Minimum water level of head tank --- EL. 434.30 m Source: JICA Survey Team

(4) Side Spillway

The side spillway with a crest length of 12.0 m is provided for the case when the power operation is

suspended, and is designed to release the maximum plant discharge of 5.0 m3/s. The overflow discharge

flows into an open channel beside the head tank and connects to the spillway pipe along the penstock.

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Preparatory Survey on North Sumatra Mini 5-27 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.1.10 PORING-2 PENSTOCK

(1) Site Conditions

The alignment of Poring-2 Penstock is along the relatively

narrow ridge line to connect Poring-2 Head Tank and

Poring-2 Powerhouse.

Ten anchor blocks are designed and concrete saddles with

an interval of 6.0 m will be provided to support the

penstock between anchor blocks.

The excavated sides and bottom surfaces are protected by

wet stone masonry with drainage pipes and ditches for

surface drainage.

The Poring-2 Penstock is 861.6 m long and 235.8 m high, and has gradient of 16.6 degrees on average

and with the maximum angle of 35.4 degrees at the section behind the powerhouse.

At the lower horizontal section, shortly after the last bend, the penstock will connect to a Y-branch pipe,

then it will be divided into two lanes and finally connect to each turbine unit.

The following Figure 5.1.29 shows the plan and profile as well as typical cross section of the penstock.

Source: JICA Survey Team

Site Conditions of Poring-2 Penstock

F

inal Report

Preparatory Survey on N

orth Sumatra M

ini 5-28

N

ippon Koei C

o., Ltd.

Hydropow

er Project (P

PP

Infrastructure Project)

S

ource: JICA

Survey Team

Figu

re 5.1.31 P

lan an

d P

rofile of Poring-2 P

enstock

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Preparatory Survey on North Sumatra Mini 5-29 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Optimum Penstock Diameter

The penstock diameter is determined by the flow velocity and it is normally set at 2.0-4.0 m/sec (NEF

Guide Book for Small Hydropower). The high head hydropower plants such as this Project tend to be

more advantage of cost comparison with smaller diameter and larger head loss to some extent.

Therefore, the average flow velocity is set at around 4.0 m/sec, which is widely applied in small

hydropower projects.

(3) Water Hammer and Closing Time

The closure time of turbine and generator is determined by the comparison of steel weight of penstock

and flywheel of turbine and generator. The longer the closure time is, the smaller the penstock weight is

due to the smaller pressure rise in the penstock. However, it requires heavier weight of flywheel of

turbine and generator. Accordingly, the closing time is set at 7 s.

Source: JICA Survey Team

Figure 5.1.32 Optimum Closure Time of Turbine and Generator

(4) Optimum Penstock Thickness

The dimensions of Poring-2 Penstock are summarized in the following Table 5.1.9. Furthermore, the

required thickness of steel penstock is calculated from internal pressure including static head and water

hammer, and from external pressure at empty condition. It is noted that the water hammer analysis applies

the Allievi Formula.

2.30

2.40

2.50

2.60

2.70

2.80

3.0 5.0 7.0 9.0 11.0

Pen

stoc

k +

Gen

erat

or

Cos

t (U

SD M

.)

Closing Time (sec.)

Assumed: Unit Rate of Steel Penstock=4,000 USD/tonGenerator=1.084 Mil. USD/2-unit for T=5.0 sec.

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Preparatory Survey on North Sumatra Mini 5-30 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 5.1.9 Water Hammer Analysis and Poring-2 Penstock Steel Thickness

Design Condition:

Discharge : Qmax = 5.0 m3/s

Static head : H0 = 241.80 m

Closing time of guide vane T = 7.0 s

Allievi Formula for water hammer:

.

√1.25 n . %

θ 4.034 ρ 0.854 n 0.211

No. Length (m)

Diameter (m)

Wave Velocity

(m/s)

Discharge Velocity

(m/s)

Coeff. of Allievi

Static head (m)

t for int. pressure

(mm)

t for ext. pressure

(mm)

Thicknesst

(mm) 1 4.00 1.250 810 4.074 0.697 0.0 1.5 6.0 6 2 113.05 1.250 810 4.074 0.697 45.1 4.9 6.0 6 3 90.50 1.250 851 4.074 0.733 67.1 6.5 6.0 7 4 108.69 1.250 887 4.074 0.764 78.6 7.3 6.0 8 5 103.57 1.250 887 4.074 0.764 83.1 7.7 6.0 8 6 92.24 1.250 887 4.074 0.764 87.1 8.0 6.0 8 7 84.65 1.250 945 4.074 0.814 102.1 9.1 6.0 10 8 122.68 1.250 1,044 4.074 0.900 175.1 14.5 6.0 15 9 120.49 1.250 1,107 4.074 0.954 238.9 19.9 6.0 20

10 4.00 0.900 1,107 4.074 0.954 238.9 19.9 6.0 20 11 12.00 0.900 1,116 3.930 0.927 238.9 14.3 6.0 15

Total or Average

858.87 (=L0)

1.244 937 (=α)

4.072 (=V0)

0.806 (=ρ)

--- --- --- 10.7

Source: JICA Survey Team

Consequently, closing time of 7.0 s, maximum water head of 306.9 m, and maximum pressure rise of

28.5% are applied in the design of the Poring-2 Penstock.

(5) Y-Branch and Branch Pipes

The penstock is divided into two lanes to connect hydraulic turbines at the lower horizontal section in

front of the powerhouse. Y-branch is applied to be open to 60 degrees for 12 m distance from the turbines

and the branch pipes are 0.9 m in diameter.

(6) Anchor Blocks

At the position of 10-No bends, the penstock is supported by concrete anchor blocks. Intermediate

positions between anchor blocks are supported by concrete saddles against vertical load. The overflow

spillway pipe is also aligned parallel to the penstock, so that the supports of the anchor blocks and saddles

will utilize the ones provided for the penstock.

The stability conditions (overturning, sliding, and bearing stabilities) are to be confirmed against each

combination of dead load, combined water pressure, deflection due to temperature change, and seismic

load.

The dimensions of anchor blocks are determined to satisfy the above requirement.

(7) Saddle Supports

Similarly, saddle support is selected and the intervals of support are 6 m.

Final Report

Preparatory Survey on North Sumatra Mini 5-31 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.1.11 PORING-2 HEAD TANK SPILLWAY

Similar design concept for Spillway-1 described in Section 5.1.7 has been applied for Poring-2 head tank

spillway. The head tank spillway is designed to be steel pipe in parallel with the penstock line instead of

discharging to the local river by open channel because of additional countermeasures to prevent the

erosion of channel foundation.

An overflow weir is provided at the inlet of the spillway pipe to allow smooth discharge. Also, an energy

dissipater is designed at the end of the pipe spillway below the erection bay of the powerhouse because

the design discharge with high head will be released. Then, the excess discharge will be released to the

Poring River.

(1) Diameter of Pipe Spillway

The flow inside the spillway pipe is supercritical flow with high velocity. To maintain less than 50% of

flow area ratio (=flow area/pipe are) for safe discharge condition as shown in the following Table 5.1.10,

the pipe diameter should be 1.25 m.

Table 5.1.10 Non-Uniform Flow Analysis for Overflow Spillway Pipe for Poring-2

Source: JICA Survey Team

(2) Energy Dissipater

It is noted that the impact type energy dissipater is provided below the concrete slab of erection bay in the

powerhouse.

Length Depth Area Velocity V head Wet R Invert EL. Slope Ratio Frude

(m) h (m) A (m2) V (m/s) V^2/2g (m) P (m) R (m) (m) θ deg <50% Fr>1

Sta.0 0.0 0.300 0.396 12.61 8.1 2.0 0.2 433.215 7.4

Sta.4 4.4 0.274 0.377 13.26 9.0 2.0 0.2 431.475 21.76 30.7% 8.1

Sta.118 114.0 0.174 0.294 17.03 14.8 1.9 0.2 386.375 21.58 23.9% 13.1

Sta.207 88.2 0.296 0.393 12.71 8.3 2.0 0.2 364.375 14.00 32.1% 7.5

Sta.315 108.4 0.447 0.499 10.03 5.1 2.0 0.3 352.875 6.06 40.6% 4.8

Sta.419 104.0 0.660 0.636 7.86 3.2 2.0 0.3 348.375 2.48 51.8% 3.1

Sta.512 92.5 0.636 0.620 8.06 3.3 2.0 0.3 344.375 2.48 50.5% 3.2

Sta.595 83.7 0.257 0.364 13.74 9.7 2.0 0.2 329.375 10.16 29.6% 8.7

Sta.717 122.1 0.123 0.244 20.48 21.5 1.9 0.1 256.375 30.88 19.9% 18.7

Sta.842 124.9 0.209 0.325 15.41 12.1 1.9 0.2 190.275 27.89 26.4% 10.8

Sta.855 12.7 0.288 0.387 12.90 8.5 2.0 0.2 190.275 0.00 31.6% 7.7

Station

Final Report

Preparatory Survey on North Sumatra Mini 5-32 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Site Conditions of Poring-2 Powerhouse

5.1.12 PORING-2 POWERHOUSE

(1) Site Conditions

The position of the powerhouse was

selected as shown in the alternative

layout study.

Powerhouse-2 is, based on the penstock

alignment on the ridge line, located on a

relatively gentle slope at the foot of the

penstock slope.

The geological investigation revealed

that rock foundation (fresh granite) will

be exposed after 5.0 m deep excavation.

The concrete slab of powerhouse will

be constructed on this rock surface. Turbine setting level is determined above this concrete slab to avoid

deep excavation in the rock foundation.

The access to the powerhouse is a newly constructed project road at the slope beside the penstock. The

difference of elevation from the existing village road to the powerhouse is 188 m and the length is 1,405

m.

Below is the H-Q Curve at Poring-2 Powerhouse Site to estimate flood water level based on flood

discharge in the hydrological study and the results of river cross section survey by non-uniform flow

Figure 5.1.33 H-Q Curve at Powerhouse-2 Site

Outlets are discharged directly into the Poring River from the front of the powerhouse. The tailrace water level

is required at more than 50 cm from the flood level. The design flood for Poring-2 Powerhouse is 100-year

probable flood (Q = 740 m3/s), so that the water depth is 12.55 m above the riverbed (EL. 193.2 m).

(2) Powerhouse Setting Levels

The powerhouse yard elevation of EL. 193.50 m is determined from the 100-year probable flood water

level of the Poring River with a freeboard of 1.0 m based on the H-Q curve below.

100-yr FloodQ= 740 m3/s H= 12.55 m

0.0

5.0

10.0

15.0

0 100 200 300 400 500 600 700 800

Wat

er D

epth

(m

)

Discharge (m3/s)

Poring-2 Powerhouse Site, Tentatively Assumed River H-Q Curve

Non-uniform Flow Analysisby River Cross Section SurveyRoughness coefficient: n=0.05

Source: JICA Survey Team

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The slab elevation is 20 cm higher than the yard elevation to prevent rainfall discharge into the

powerhouse.

Turbine center level as well as tail water level and penstock center level are determined as explained in

the electro-mechanical design.

Table 5.1.11 Poring-2 Powerhouse Setting Level

Turbine Center Elevation EL. 194.40 m (≤ TWL + Hs*)

Surface Level of Powerhouse Concrete EL. 193.70 m (Yard Level + 0.20 m)

Powerhouse Yard Level (Yard EL) EL. 193.50 m (= FWL + freeboard (= 1.00 m)

Penstock Center Elevation (PCL) EL. 193.00 m (= Turbine Center - A*)

Tailwater Level (TWL) EL. 193.00 m (=FWL + 0.50 m)

Flood Water Level (FWL) (100-year Probable Flood) EL. 192.50 m (from H-Q Curve)

Note: Hs* and A* are explained in the design of the electro-mechanical equipment. Source: JICA Survey Team

(3) Superstructures

The Poring-2 Powerhouse shall incorporate two units of turbine and generator, erection bay, and control

room for operation with dimensions of 10.8 m (width) × 38.0 m (length) × 9.0 m (height).

The superstructure of the powerhouse for ceiling and overhead crane is designed to be a steel frame

structure. The capacity of overhead crane is 20 ton and crane girder is provided.

The plan and profile of Poring-2 Powerhouse are shown below.

Source: JICA Survey Team

Figure 5.1.34 Plan of Poring-2 Powerhouse

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Source: JICA Survey Team

Figure 5.1.35 Profile of Poring-2 Powerhouse

(4) Powerhouse Yard

Powerhouse yard is a space to accommodate the powerhouse building and tailrace culvert as well as

auxiliary facilities such as main transformer, emergency diesel, and transmission line equipment.

Powerhouse yard with dimensions of 50 m × 20 m requires relatively large excavation at the foot of the

steep slope of penstock. To reduce the excavation volume, the excavation slope should be 1:0.5 and

covered with protection. The protection work is designed to be reinforced concrete frame.

(5) Powerhouse Yard

As described in the previous chapter, hydraulic turbine is 2 units × 5,000 kW and generator is 2 units ×

5,380 kVA.

(6) Tailrace

Poring-2 Tailrace is directly discharged to the Poring River. The water level of the draft pond varies

depending on the plant discharge, but it is important to keep the water level higher to prevent the air from

entering into the draft tube.

To control the water level, an overflow weir is designed at the tailrace. The velocity of the tailrace is

designed to be smaller than 1.0 m/s by increasing the cross sectional area to reduce water surface

fluctuation and head loss.

Final Report

Preparatory Survey on North Sumatra Mini 5-35 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.2 BASIC DESIGN OF HYDRO-MECHANICAL WORKS

5.2.1 GENERAL

The hydro-mechanical works (gates and penstock) of the project includes the work items in Table 5.2.1.

Table 5.2.1 Equipment List of Hydro-Mechanical Works

No. Major Structure Hydro-Mechanical Equipment Poring-1 Poring-2

1 Intake Weir Sand Flush Gate and Hoist 1 set Nil

Sand Flush Gate Stoplog (1 set) Nil

2 Intake Facility Power Intake Trashrack 2 sets Nil

Power Intake Gate and Hoist 2 set 1 set

Power Intake Stoplog (1 set) (1 set)

3 Sand Trap Basin Sand Drain Gate and Hoist 2 set Nil

Sand Trap Basin Trashrack 2 set Nil

4 Head Tank Sand Drain Gate and Hoist 1 set 1 set

Sand Trap Basin Trashrack 1 set 1 set

5 Penstock Steel Penstock including Bifurcation 1 lane 1 lane

6 Head Tank Spillway Steel Spillway Pipe 1 lane 1 lane Source: JICA Survey Team

The conceptual designs of the hydro-mechanical works are made based on the principal design conditions,

i.e., water levels, size, quantity, sill elevation, diameter and length of penstocks, which are determined by

the overall optimization studies for this project, as described in the other sections of this study.

This section outlines the main features of the hydro-mechanical works, i.e., type, materials, construction,

for which the project costs are estimated.

The principal and fundamental factors and requirements of the hydro-mechanical works are:

to have sufficient strength and stiffness against the expected load,

to have enough watertightness for the intended purpose,

to have easy and reliable operation,

to be durable and of robust construction for long-term use,

to have no vibration when used, and

to have easy maintenance.

5.2.2 SAND FLUSH GATE AND HOIST

One sand flush gate at the intake weir will be provided at the fixed weir for flushing the sediments

accumulated in front of the intake so as to secure water intake at any time, as well as for discharging and

controlling the excessive water during flood condition.

The size of this gate is determined to be 2.0 m wide by 2.0 m high.

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(1) Gate Leaf

The plate girder, fixed-wheel steel gate is selected for the sand flush gate, among others, because of

simple and durable construction and easy and fast manufacturing and installation.

The gate leaf is all-welded steel made of 4-edge rubber seals at the upstream side of the gate leaf.

(2) Hoist

The manually operated stationary rack type hoist is applied for this gate to reduce the lifting force because

of its relatively large lifting load.

(3) Guide Frame

The guide frame is provided to guide the gate leaf in smooth operation and to transmit the water load

acting on the gate leaf to the concrete structures, to keep the watertightness with the rubber seals of the

gate leaf. The bearing plates and sealing plates are made of corrosion-resisting steel because it is difficult

to keep paints on the plates.

Table 5.2.2 Specification of Sand Flush Gate

Item Design Data

Type Plate Girder, Fixed-wheel Steel Gate

Hoist Manual Rack Type

Water-tightness 4-edge Rubber Seals at Upstream Side of Gate

Size Clear Span of 2.0 m × Clear Height of 2.0 m

Guide Frame 11.0 m (height)

Sill EL. EL. 641.7 m

Design Water Level FWL. 651.45 m Source: JICA Survey Team

5.2.3 SAND FLUSH GATE STOPLOG

The slot of one vertical lift slide gate type stoplog will be provided at the upstream side of the sand flush

gate for the purpose of maintenance and repair of Sand Flush Gate and its guide frames.

(1) Gate Leaf

The gate leaf of the sand flush gate stoplog is not provided, because the Stoplog leaf is transported and

utilized for the sand flush gate maintenance.

(2) Hoist

Because of drare operation, permanent hoist is not provided. The Stoplog leaf is lifted up and lowered

down by using manually operated chain block, etc. For the handling of stoplog, a mobile crane will be

used when required.

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(3) Guide Frame

The concrete slot is provided at 2.0 m upstream side of the Sand Flush Gate. Guide Frames are not

provided taking operation frequency and required water-tightness into consideration.

Table 5.2.3 Specification of Sand Flush Gate Stoplog

Item Design Data

Type Plate Girder, Slide Type Steel Stoplog (common use with sand flush gate stoplog)

Hoist Manually Operated Lifting Tools (Temporary)

Water-Tightness 4-Edge Rubber Seals at Downstream Side of Gate

Slot 2.0 m wide and 11.0 m high

Sill EL. EL. 641.80 m

Design Water Level EL. 646.50 m Source: JICA Survey Team

5.2.4 POWER INTAKE TRASHRACK

Two sets of trashracks will be provided at the inlet of the power intake in order to prevent drifting foreign

material from entering into the sand trap basin. Trash caught by the trashrack will be removed manually.

The trashracks are to have sufficient strength and suitable structure to withstand the impact force, static

and all other loads and vibration phenomena which would likely occur due to the inflow of water. The

water head difference of 1.0 m is applied for the design head of the trashracks.

Table 5.2.4 Specification of Power Intake Trashrack

Item Design Data

Type Fixed Type Bar Screen

Size Clear Span of 3.0 m × Vertical Height of 2.0 m (Inclination 1:0.5)

Bar Pitch 100 mm

Sill EL. EL. 643.5 m

Design Head 1.0 m across the screen Source: JICA Survey Team

5.2.5 POWER INTAKE GATE AND HOIST

(1) Gate Leaf

Two power intake gates will be provided at the inlet of the intake channel for shutting off the water flow

to the sand trap basin. The plate girder, fixed-wheel steel gate is selected for the power intake gate.

(2) Hoist

The stationary rack type hoist is applied because the power intake gate has to have a function of shutting

off at one/both sand traps under [Q = 6.0 m3/s for 100% power generation] without electricity to protect

the waterway from fatality in the case of emergency situation. This gate will be operated frequently

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because it controls water flow with gate position. With such situation, motor driven type is applied to

reduce work load of operator. It will be controlled only with local control because the operators always

are at local control room.

(3) Guide Frame

The guide frame is provided to keep the watertightness with the rubber seals of gate leaf, to guide the gate

leaf during operation, and to transmit the water load acting on the gate leaf to the concrete structures. The

sealing frames consist of sealing plate made of corrosion-resisting steel plate and are connected to the sill

beam and front frames.

Table 5.2.5 Specification of Power Intake Gate

Item Design Data

Type Plate Girder, Fixed-wheel Steel Gate

Hoist Motorized Rack Type

Water-Tightness 4-edge Rubber Seals at Upstream Side of Gate

Quantity 2 Sets

Size Clear Span of 2.0 m × Clear Height of 2.0 m

Guide Frame 9.20 m high

Sill EL. EL. 643.50 m

Design Water Level FWL. 651.45 m Source: JICA Survey Team

5.2.6 POWER INTAKE STOPLOG

Two sets of vertical lift slide gate type stoplog will be provided at the upstream side of the power intake

gates for the purpose of maintenance and repair of the gate and its guide frames. The stoplogs have the

same functions and component of the stoplog for the sand flush gate. Because of drare operation,

permanent hoist is not provided. The Stoplog leaf is lifted up and lowered down by using manually

operated chain block, etc. For the handling of stoplog, a mobile crane will be used when required.

Table 5.2.6 Specification of Power Intake Gate Stoplog

Item Design Data

Type Plate Girder, Slide Type Steel Stoplog (common use with tailrace stoplog)

Hoist Manually Operated Lifting Tools

Water-Tightness Nil

Size Clear Span of 2.0 m × Clear Height of 2.0 m

Slot 2.00 m wide and 9.20 m high

Sill EL. EL. 643.5 m

Design Water Level FSL. 646.50 m Source: JICA Survey Team

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5.2.7 SAND DRAIN GATE AND HOIST AT SAND TRAP

Two sand drain gates will be provided in front of the starting point of the headrace channel for flushing

the sediments such as sand and mud accumulated in the sand trap. As the gate size is small, slide type

gate is selected instead of roller gates. Manual spindle type hoist will be applied for the sand drain gate

because of a few oppotunity of operation and small operating loads.

In addition, a valve for environmental maintenance will be provided at the sand trap.

Table 5.2.7 Specification of Sand Drain Gate at Sand Trap Basin

Item Design Data

Type Plate Girder, Slide Type Steel Gate

Hoist Manual Spindle Type

Water-Tightness 4-edge Rubber Seals at Upstream Side of Gate

Quantity 2 Sets

Size Clear Span of 1.0 m × Clear Height of 1.0 m

Guide Frame 7.50 m high

Sill EL. EL. 640.0 m

Design Water Level EL. 647.01 m (FWL in Sand Trap)

Type of Valve Butterfly Valve

Diameter of Valve φ300

Valve EL. EL. 642.5m Source: JICA Survey Team

5.2.8 SAND TRAP TRASHRACK

Two trashracks will be provided at the end of the de-silting basin in order to prevent drifting foreign

matters from entering into the headrace channel. The trashrack has sufficient strength, stiffness and

suitable structure to withstand the impact force, static and all other loads, and vibration phenomena which

would likely occur due to the inflow of water. Trash caught by the trashrack will be removed manually.

The water head difference of 1.0 m is applied for the design head of the trashracks.

Table 5.2.8 Specification of Sand Trap Trashrack

Item Design Data

Type Fixed Type Bar Screen

Size Clear Span of 3.0 m × Vertical Height of 3.5 m (Inclination: 1:0.5)

Quantity 2 Sets

Bar Pitch 100 mm

Sill EL. EL. 644.0 m

Design Head 1.0 m across screen Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 5-40 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.2.9 SAND DRAIN GATE AND HOIST AT HEAD TANK

One sand drain gate will be provided at each head tank for flushing the sediments such as sand and mud

accumulated in the head tank. Slide type gate is selected instead of roller gates as well as the de-silting

basin sand drain gate. Manual spindle type hoist will be applied for the sand drain gate because of few

operations and small operating loads.

Table 5.2.9 Specification of Sand Drain Gate at Head Tank

Item Poring-1 Poring-2

Type Plate Girder, Slide Type Steel Gate Plate Girder, Slide Type Steel Gate

Hoist Manual Spindle Type Manual Spindle Type

Quantity 1 Set 1 Set

Water -Tightness 4-Edge Rubber Seals at Upstream Side

of Gate

4-Edge Rubber Seals at Upstream Side

of Gate

Size Clear Span of 1.0 m × Clear Height of

1.0 m

Clear Span of 1.0 m × Clear Height of

1.0 m

Guide Frame 4.20 m high 4.20 m high

Sill EL. EL. 636.80 m EL. 432.20 m

Design Water Level EL. 641.00 m (Spillway crest level) EL. 436.40 m (Spillway crest level) Source: JICA Survey Team

5.2.10 HEAD TANK TRASHRACK

One trashrack will be provided at each inlet of the penstock in order to prevent drifting foreign material

from entering into the hydraulic turbines. The trashracks are to have sufficient strength and suitable

structure to withstand the impact force, static and all other loads, and vibration phenomena which would

likely occur due to the inflow of water. The water head difference of 1.0 m is applied for the design head

of the trashracks.

Table 5.2.10 Specification of Head Tank Trashrack

Design Conditions Poring-1 Poring-2

Type Fixed Type Bar Screen Fixed Type Bar Screen

Size Clear Span of 6.00 m × Vertical Height

of 3.50 m (Inclination of 1:0.3)

Clear Span of 5.00 m × Vertical Height

of 3.50 m (Inclination of 1:0.3)

Bar Pitch 70 mm 70 mm

Sill EL. EL. 638.50 m EL. 433.90 m

Design Head 1.0 m across screen 1.0 m across screen Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 5-41 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.2.11 PENSTOCK AND SPILLWAY PIPE

(1) Material for Penstock and Spillway Pipe

Steel has been widely used for penstock as a conventional material, but recently, fiber (fiberglass)

reinforced plastic (FRP) has been used as an alternative material for steel. The comparison study between

steel and FRP pipes to be used for penstock is shown in the following table:

Table 5.2.11 Material Comparison between Steel and FRP

Description Steel FRP

Structure

Unit steel pipes are connected by welding and form a continuous beam. There is no joint except the expansion joint provided between anchor blocks. Steel pipe is supported on saddles and fixed by anchor block.

Each unit pipe is connected with a coupling provided to each pipe, and accordingly there are joints at the respective couplings. Each unit pipe is fixed by thrust collar at each saddle support.

Design Standard Established and verified from experiences for long time

Recently established and not so long experience

Verification of Strength Conservatively verified by allowable stress method

Verified by similar allowable stress method or other method

Ease of Construction

Welding for unit pipe connection is slightly complicated.

Compared with steel pipe, as weight of FRP pipe is lighter, the handling for construction is easier than steel pipe. The connection of unit pipe is simple and easy with slip-on coupling.

Corrosion Resistance Steel tends to be corroded if no protection. Plastic is stable against chemical reaction such

as corrosion.

Abrasion Resistance Compared with plastic, steel is stable against abrasive material such as sand.

Without protection, plastic is weak against abrasive material.

Weathering Resistance

Steel will be corroded under acid environment. If properly protected, long lifetime will be expected.

If plastic is exposed under the conditions of high temperature and/or strong UV ray, it will be deteriorated in a short time.

The stability of structure is essential for the function of penstock considering safety of high pressure

waterway. Taking into account the established and verified technology of steel penstock, steel should be

adopted as the material of penstock and spillway pipe for conservative design in this stage. Because FRP

has merits during the construction stage and O&M, it might be applied to penstock and spillway pipe

provided that further study should be considered for the structural stability and durability against

abrasion/weathering resistance.

Expansion joint

Saddle supports

Steel pipe

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Preparatory Survey on North Sumatra Mini 5-42 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Steel Penstock

One complete lane of steel penstock with one bifurcation and two branches will be provided for supplying

the water from the head tank to two hydraulic turbines in the powerhouse. The diameters of penstock are

1.35 m and 1.25 m for the one lane section, and 1.0 m and 0.9 m after the two branches.

The internal pressure is the sum of static head and the pressure rises due to water hammer. The shell

thickness of the steel penstock is designed so that the shell itself have sufficient strength against the

design internal pressure without expecting any support from the surrounding concrete/rock.

Expansion joints are provided at the immediate downstream of each anchor block to absorb the

longitudinal movements due to alteration of temperature.

Ventilation pipes are provided at bend to avoid damages by negative pressure.

Y-type bifurcation is provided at the inclined bottom portion of the penstock to be encased with concrete

and backfilled in front of the powerhouse.

Table 5.2.12 Specification of Penstock

Item Poring-1 Poring-2

Diameter 1.35 m (1 lane) ~ 1.00 m (Branch pipe: 2 lanes)

1.25 m (1 lane) ~ 0.90 m (Branch pipe: 2 lanes)

Total Length 430.9 m 857.3 m

Static Head 199.5 m 243.2 m

Water Hammer 30.0% at center line of Water Turbine 30.0% at center line of Water Turbine

Thickness 6.0 mm ~ 12.0 mm 6.0 mm ~ 19.0 mm Source: JICA Survey Team

(3) Spillway Pipe

The head tank spillway steel pipe is provided in parallel to the steel penstock to safely release the excess

discharge of the head tank to the tailrace. To maintain less than 50% of flow area ratio (=flow area/pipe

area) for safety discharge condition, the pipe diameters are 0.95 m for Poring-1 and 1.25 m for Poring-2.

The design load is the deadweight of the pipe and water. The internal pressure is not applied because the

excess discharge will flow with the free water surface. Ventilation pipes will be installed at the bend to

prevent negative pressure.

Table 5.2.13 Specification of Head Pond Spillway Pipe

Item Poring-1 Poring-2

Diameter 0.95 m 1.25 m

Total Length 430.4 m 854.5 m

Thickness 6.0 mm 6.0 mm Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 5-43 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.3 BASIC DESIGN OF ELECTRO-MECHANICAL WORKS

5.3.1 BASIC DESIGN CONDITIONS

(1) Applied Standards

All electrical and electromechanical equipment are designed to comply with the latest revision of the

authorized standards of the International Electro-technical Commission (IEC) as much as applicable.

(2) Service Conditions

All electrical and electromechanical equipment are designed for satisfactory operation under the

following service conditions:

Ambient temperature : Not exceeding 40C

Water temperature : Not exceeding 28C

Altitude : Not exceeding 1,000 m

5.3.2 HYDRAULIC TURBINES

(1) Operating Water Level Conditions

Hydraulic turbines are designed to operate under the following conditions:

Table 5.3.1 Operating Water Level Conditions Item Poring-1 Poring-2

Intake Water Level (at Intake Weir) Full Supply Water Level (FSL)

EL. 646.5 m

EL. 441.6 m

Intake Water Level (at Head Tank) Full Supply Water Level (FSL) Rated Water Level Minimum Operational Level (two-unit) Minimum Operational Level (one-unit)

EL. 641.0 m EL. 641.0 m EL. 640.8 m EL. 640.6 m

EL. 436.4 m EL. 436.4 m EL. 436.2 m EL. 436.0 m

Tail Water Level Flood water level Water Level at Two-unit Operation Water Level at One-unit Operation Low Water Level (no-flow)

EL. 441.5 m EL. 441.8 m EL. 441.5 m EL. 441.1 m

EL. 192.7 m EL. 193.0 m EL. 192.7 m EL. 192.3 m

Head Loss Head Loss due to Two-unit Operation Head Loss due to One-unit Operation

6.0 m 2.0 m

11.1 m 3.3 m

Gross Head and Net Head Maximum Gross Head: Hg Maximum Net Head: Hmax *1 Design Head (Rated Head): Hd *2 Minimum Net Head: Hmin *3

646.5-441.1=205.4 m

641.0-441.5-2.0=197.5 m 641.0-441.8-6.0=193.2 m 640.6-441.8-6.0= 192.8 m

441.6-192.3=249.3 m

434.4-192.7-3.3=240.4 m 436.4-193.0-11.1=232.3 m436.0-193.0-11.1= 231.9 m

Note: *1 = 1-unit operation at rated output, *2 = 2-unit operation at rated output, *3=2-unit operation at guide vanes fully opened Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 5-44 Nippon Koei Co., Ltd.

Hydropower Project (PPP Infrastructure Project)

(2) Turbine Output

The turbine rated output is expressed by the following equation:

(kW)

where, is the turbine output (kW), is the unit discharge (m3/s), is the rated head (m), is the

turbine efficiency = 0.92.

Table 5.3.2 Turbine Output

Item Poring-1 Poring-2

Unit discharge: 6.0 / 2 = 3.0 m3/s/ 5.0 / 2 = 2.5 m

3/s

Rated head: 193.0 m 232.2 m

Turbine efficiency: 88.6% 92.4%

Turbine output: 5,000 kW 5,000 kW Source: JICA Survey Team

(3) Type of Turbine

Referring to the selection chart for turbine type, a horizontal-shaft Francis turbine is selected for the rated

output of 5,000 kW and rated heads (design head) of 193.0 m for Poring-1 and 232.2 m for Poring-2.

Figure 5.3.1 Selection Chart for Turbine Type

(4) Rated Speed and Specific Speed

In general, the larger rotational speed is proportional to the smaller size turbine and generator, which

result in an advantage of equipment cost. Due to the limitation of the specific speed, smaller than 1,000

rpm is applicable for the rotational speed.

However, the turbine and generator setting is deeper than the ground level at N=1,000 rpm because the

Poring-1

Poring-2

1

10

100

1000

0.01 0.1 1 10 100

He (m)

Q (m3/sec)

Poring-1

Poring-2

Pelton

Turgo Impulse

Francis (H)

Francis (V)

Kaplan

Reverse Pump

Propeller (Siphone)

Crossflow

Submersible Pump

Tubular (S)

Propeller (Inline)

Source: NEF Small Hydropoewr Guidebook, 2005

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Preparatory Survey on North Sumatra Mini 5-45 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

draft head (Hs) is smaller, and the turbine center is lower than the tailwater level, so that civil

construction cost will be increased by greater rock excavation as well as care of water and slope

protection during construction, higher powerhouse building, and for ease of construction. Such risks are

normally prevented particularly for horizontal axis turbine and generator. Accordingly, rated rotational

speed of N=750 rpm was selected.

Table 5.3.3 Specific Speed (Ns)

Item Poring-1 Poring-2

Limitation of Specific Speed Ns 143 mkW 128 mkW

Limitation of Rotational Speed N 1,458 rpm 1,640 rpm

Nearest Rotational Speed N 750 rpm 750 rpm

Calculated Specific Speed Ns 74 mkW 59 mkW Source: JICA Survey Team

(5) Turbine Setting Level and Runaway Speed

The turbine setting level is defined as the elevation of the centerline of turbine distributor and is

calculated from the tailrace water level at one-unit operation.

Table 5.3.4 Turbine Setting Level

Item Poring-1 Poring-2

Cavitation Coefficient, σp 0.031 0.022

Rated Head, Hd 193.00 m 232.20 m

Atmospheric Pressure at TWL, Ha 9.80 m 10.10 m

Vapour Pressure at Water Temperature T=22C, Hv 0.30 m 0.30 m

Suction Head, Hs 3.62 m 4.78 m

Distance between Turbine and Runner Centers, I 0.35 m 0.40 m

Tailrace Water Level at One-unit Full Operation, TWL EL. 441.60 m EL. 192.60 m

Maximum Turbine Center Setting Level Lower than

EL. 444.90 m

Lower than

EL. 197.00 m Source: JICA Survey Team

Table 5.3.5 Maximum Runaway Speed

Item Poring-1 Poring-2

Runaway Speed (Nr) 1,208 rpm 1,191 rpm

Maximum Runaway Speed (Nrmax) 1,218 rpm 1,206 rpm Source: JICA Survey Team

(6) Inlet Valve

The maximum static water pressure head for the inlet valve is 640.0-443.5=196.5 m for Poring-1 and

434.0-194.5= 239.5 m for Poring-2. Referring to Table 5.3.6 below, through-flow type butterfly valve is

applied to the inlet valve with maximum static head of around 200 m.

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Preparatory Survey on North Sumatra Mini 5-46 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 5.3.6 Comparison of Performance of Inlet Valves

Item Spherical Valve Butterfly Valve Through-flow Valve

Applicable head (max. static head) Above 200 m Below 200 m Below 300 m

Coefficient of head loss of inlet valve Very small Large Relatively small

Allowable leakage water from main valve Very small Large Relatively small

Price High Low Low Source: JICA Survey Team

(7) Main Water Supply System

The main water supply system designed to provide the cooling water to the turbine guide bearing,

generator thrust, and guide bearings and turbine sealing water for Poring-1 and Poring-2 is based on a

direct water supply system from the penstock. The necessary cooling water quantity will be relatively

little because the air cooling method is applied to the generater as mentioned below. By applying a direct

water supply system, pressure reducer shall be installed near the intake point in consideration of the rated

heads of Poring-1 and Poring-2.

(8) Water Drainage and Dewatering System

The water drainage system is required to discharge the water from the station sump pit to the tailrace. On

the other hand, the dewatering system is required to discharge the water in the draft tube to the tailrace

espacially during maintenace of the turbine runner. In case of Poring-1 and Poring-2, the turbine center

level will be set higher than the tailrace water levels, then the maintenance of the turbine runner can be

carried out without dewatering in the draft tube. When dewatering in the draft tube is required, once the

water in the draft tube is discharged to the station sump pit, the water is discharged to the tailrace by the

water drainage pumps.

The water drainage system will consist of two AC motor-driven drainage pumps, two water level

switches, and water piping complete with all necessary pipes and valves to discharge the water in the

station sump pit to the tailrace. Two pumps for drainage water system will be arranged for

normal/standby duty operation.

Types and ratings of the water drainage pumps are determined as shown in Table 5.3.7 below.

Table 5.3.7 Types and Ratings of Drainage Pumps

Items Specifications

(a) Type of drainage pump Submersible type

(b) Displacement volume of each pump 1.0 m3/min

(c) Pumping head 30 m Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 5-47 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

5.3.3 GENERATORS

(1) Generator Output

The generator output (Pg) is calculated from the turbine output by the following equation:

Pg Pt ∙ ηg ∙ 1/cosθ (kVA)

where, Pt is the turbine output (kW), ηg is the generator efficiency and cosθ is the power factor.

Table 5.3.8 Power Output of Generator

Item Poring-1 Poring-2

Turbine Output, Pt 5,000 kW 5,000 kW

Generator Efficiency, ηg 97.0% 97.0%

Power Factor, cosθ 0.90 0.90

Generator Output, Pg 5,380 kVA 5,380 kVA Source: JICA Survey Team

(2) Type of Generator

The generators for Poring-1 and Poring-2 are of three-phase, horizontal-shaft, synchronous alternator

type.

(3) Generator Rated Voltage

The generator rated voltage of Poring-1 and Poring-2 is selected as 6.6 kV.

(4) Generator Neutral Grounding System

The neutral point of the generator stator winding will be grounded through a neutral grounding

transformer with a secondary resistor.

(5) Synchronizing Method of Generator

The generator synchronizing will be made by the 6.6 kV circuit breaker on the generator circuit.

(6) Flywheel Effect (GD2) of Generator

Flywheel Effect of Turbine and Generator

In accordance with the USBR Standard1, the flywheel effect of the turbine (GD t) and generator (GD n

is calculated by the following equation:

GD t 3.9428 ∙ Pt/N . . (tonm2)

GD n 60 Pg/N . . (tonm2)

1 Engineering Monograph No. 20 of US Bureau of Reclamation (Revised in 1976)

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Preparatory Survey on North Sumatra Mini 5-48 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

where, Pt is the turbine output (kW), Pg is the generator output (kW), N is the rated rotational speed

(rpm).

Table 5.3.9 Fly Wheel of Turbine and Generator

Item Poring-1 Poring-2

Turbine Output, Pt 5,000 kW 5,000 kW

Generator Output, Pg 4,850 kW, 5,380 kVA 4,850 kW, 5,380 kVA

Rated Rotational Speed, N 750 rpm 750 rpm

Flywheel Effect of Turbine, GD t 0.68 tonm2 0.68 tonm2

Flywheel Effect of Generator, GD n 11.24 tonm2 11.24 tonm2 Source: JICA Survey Team

The flywheel effect of a generating unit (turbine and generator) shall be sufficient to insure prompt

response to changes in load demands.

Conditions to respond to changes in load demands: GD21

Conditions to respond to speed rise and pressure rise: GD22

The required flywheel effect of the generator (GD2r) is determined to satisfy the following relationship:

GD2r GD2u GD2t (tonm2)

where, GD is the required flywheel effect of generator, = GD and GD whichever is larger, and

GD is the required flywheel effect of turbine.

Table 5.3.10 Necessary Fly Wheel of Turbine and Generator

Item Poring-1 Poring-2

Required Flywheel Effect of Turbine, GD2t 0.68 tonm2 0.68 tonm2

Required Flywheel Effect of Generating Unit, GD2u 10.46 tonm2 15.58 tonm2

Required Flywheel Effect of Generator, GD2r 9.78 tonm2 14.90 tonm2 Source: JICA Survey Team

As studied above, the additional fly wheel will not be required for the generator in Poring-1. However, for

Poring-2, it will be necessary to install the additional fly wheel which has a weight of 32.5% of its

generator.

5.3.4 MAIN TRANSFORMERS

(1) Type and Cooling Method

The main transformers are of single-phase, oil-immersed, two-winding, outdoor installation type intended

to be connected directly to the 6.6 kV busbar in the power station. The cooling method is selected to be

natural oil circulation forced air cooling (ONAF). In case some problems occur in the cooling fans, the

main transformer is able to be operated under ONAN mode which has 70% capacity of the rated power of

the main transformer.

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Preparatory Survey on North Sumatra Mini 5-49 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Main Transformer Rated Power

The rated power of the main transformers should be 11,000 kVA for three-phase which corresponds to the

generated power of two units.

(3) Main Transfomer Rated Voltage

The rated voltage of the main transformers should be 6.6 kV at primary winding and 33 kV at secondary

winding. Main transformer is equipped with on-load tap changer of ±1.5%

5.3.5 BASIC ELECTRICAL CONNECTION IN POWER STATION

(1) Transmission System

The generated power of Poring-1 and Poring-2 power stations is evacuated to PLN’s Tarutung Substation

located approximately 35 km by two 33 kV circuits with one pole line for each power station, which will

be constructed along the existing public road and operated and maintained by the project. The above 33

kV transmission line is a branch line for power supply to the equipment and facilities at the intake weir

and head tank of Poring-1 and Poring-2, respectively.

(2) Main Circuit

Control of Generating Unit

The generating units are designed to be operated and controlled from the control room of the Poring

power stations, and remote control from the PLN substation is not required.

Synchronizing of Generator

The generator is designed to make synchronization by a generator voltage (6.6 kV) circuit breaker or a

distribution line (33 kV) circuit breaker. In case of start/stop operation of a generating unit, the

synchronization is made by a generator voltage circuit breaker to conveniently carry out changeover of

the station service.

Generator Voltage (6.6 kV) Switchgear

The generator voltage switchgear is designed for the following ratings:

(a) Rated voltage : 7.2 kV

(b) Rated normal current : 630 A

(c) Rated short-time withstand current : 25 kA

Station Service Power Supply System

The electric power to the equipment and facilities in the power station is supplied from 6.6/0.4 kV station

service transformer which is a three-phase, indoor installation and dry type transformer connected to 6.6

kV busbar. In case of shutdown of station service or black start of generator, an emergency diesel engine

generator is operated.

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Preparatory Survey on North Sumatra Mini 5-50 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

DC Power Supply System

DC 110 V supply system is required to be installed in the powerhouse for the operation voltage of the

switchgear. The stationary batteries will be designed as follows:

(a) Type : Sealed construction, valve regulated type, lead acid batteries

(b) Capacity : 300 AH at 10-hour discharge rate

(c) Number of cells : 53 cells/set

5.3.6 POWERHOUSE CRANE

(1) Lifting Capacity

The required lifting capacity of the powerhouse crane will be determined from the estimated weight of the

generator rotor.

The weight of the generator rotor will be estimated from the generator output and rotational speed using

the following formula:

Water Power and Dam Construction (Nov. 1978)

Wr = 50*(Pg/N0.5)0.74 (ton)

Wr = 50*(5.38/7500.5)0.74 (ton)

= 15.0 (ton)

Where, Wr: Rotor weight (ton), Pg: Generator output (MVA), N: Rotational Speed (rpm)

Static Data in Japan for Semi-Umbrella Type Generator

Wr = 1.5393*(Pg*1,000)0.7166*N-0.6001 (ton)

Wr = 1.5393*(5.38*1,000)0.7166*750-0.6001 (ton)

= 13.7 (ton)

As shown above, the weight of the generator rotor is calculated as 15.0 ton.

(2) Lifting Capacity

The following Table 5.3.11 shows the specification of the powerhouse crane for Poring-1 and Poring-2.

Table 5.3.11 Outline Specification for Powerhouse Crane

Powerhouse Crane Poring-1 Poring-2

Estimated weight of generator rotor 15.0 ton 15.0 ton

Estimated weight of lifting beam 2.0 ton 2.0 ton

Required lifting capacity 17.0 ton 17.0 ton

Rated lifting capacity of main hook 20 ton x 1 20 ton x 1

Span of crane rails 8.7 m 8.7 m Source: JICA Survey Team

Final Report

Preparatory Survey on North Sumatra Mini 6-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 6 CONSTRUCTION PLAN

6.1 CONSTRUCTION PLAN

6.1.1 BASIC CONDITION

Major structure in this project are shown below

- Access Road : length of refurbishment (24 km, including vertical aliment improvement 6.8 km3)

Earth work volumes of access road were estimated by the average cross-sectional method from

cross-section of the 25m interval. Earth Fill materials are used to the excavation materials.

Table 6.1.1 Quantities of Access Road Work

Unit Quantity

Excavation m3 260,000

Earth fill m3 91,000 Source: JICA Survey Team

- Poring-1 : Intake (width33.0 m ×height 7.0 m), Headrace Channel (length 2,490m, width 1.9 m

× height 2.0m), Head Tank, Penstock (length 426m, 1.35m, Spillway pipe0.95 m),

Powerhouse

- Poring 2 : Headrace Channel (length 2,581m, width1.6m × height 1.9m), Head Tank, Penstock

(length 860m, 1.25m, Spillway pipe 1.25 m), Powerhouse

The following items are Key factor which will affect the method statement and schedule. The quantities

of main construction work have been estimated from the basic design drawings.

Table 6.1.2 Quantities of Main Work

Source: JICA Survey Team

Unit Excavation Earthfill ConcreteIntake m3 13,500 816 4,524 Waterway m3 83,179 6,535 5,880 Head Tank m3 3,110 160 593 Penstock m3 48,630 480 1,430 Powerhouse m3 13,700 150 1,100 Project Road m3 24,030 9,970 ----- Waterway m3 79,057 7,091 6,637 Head Tank m3 2,550 200 402 Penstock m3 136,180 460 2,570 Powerhouse m3 8,780 150 970 Project Road m3 43,324 12,346 -----

456,039 38,358 24,106 Total

Pori

ng-2

Pori

ng-1

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Preparatory Survey on North Sumatra Mini 6-2 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(1) Weather Condition

Yearly average temperature at project area is around 24℃. Yearly average rainfall is 3,448mm. The

amount of rainfall is quit high through a year. But the trend shows the rainfall from August to December

is more than other season.

(2) Construction Material

1) Cement

Normal Portland cement will be used. The supplier will be Padang cement. The cement will be

transported by ship to Sibolga from Padang port and transported to site by truck.

2) Aggregate

Aggregate will be purchased from the supplier in Tarutung. Considering the concrete schedule, we should

plan to stock the aggregate for the concrete volume which will be used in one week period.

3) Sand

Sand will be purchased from the supplier in Tarutung. Considering the concrete schedule, we should plan

to stock the sand for the concrete volume which will be used in one week period.

4) Re-bar

Re-bar will be purchased from the supplier in Medan. Re-bar will be supplied by in-land transportation

from Medan.

5) Rock material for masonry

Rock material will be taken from rock excavation by blasting. Also, rock material will be corrected from

river around site.

(3) Workable days

For the planning of construction method, following condition will be used considering Indonesian local

situation.

- Working hours : 8:00 ～ 17:00 （no night shift）

- Workable days：monthly average 20days（earth work）, monthly average23days（concrete and

other works）

Fixed holidays are Sunday of every other week. (Hariraya holidays are excluded)

6.1.2 CONSTRUCTION SCHEDULE

Construction period for preparatory access road work is 6 months, and Main work is 36 months, by the

planning of method statement and quantities which is made from basic condition. Each commissioning

test at construction schedule were estimated for Poring-1 mini hydropower project at 27 months and

Poring-2 mini hydro project at 36 months including 4 month allowance. The construction schedule of

preparatory access road work and main work are shown below.

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Preparatory Survey on North Sumatra Mini 6-3 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 6.1.1 Preparatory Access Road Work

Access Road worksMobilization LS 1

Earth work (Excavation) cu.m 260,000Earth work (Earthfill) cu.m 92,000Pavemnt work (Gravel) sq.m 40,000Pavemnt work (Concrete) sq.m 30,000Drainage & culvert work LS 1

Demobilization LS 1

Mar.Nov. Dec.2016 2017

Unit QuantityAug. Sep. Oct. Jan. Feb.

F

inal Report

Preparatory Survey on N

orth Sumatra M

ini 6-4

N

ippon Koei C

o., Ltd.

Hydropow

er Project (P

PP

Infrastructure Project)

S

ource: JICA

Survey Team

Figu

re 6.1.2 M

ain W

ork S

ched

ule

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Preparatory Survey on North Sumatra Mini 6-5 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

6.1.3 PREPARATORY ACCESS ROAD WORK

In the road from Tarutung to project site, 24km of the road to project side should be improved. The

section to be improved is from Aek Nauli village to Siantar Naipospos village. Only motorbike can go

through the existing road. The improvement work makes the road wide enough for passing by

construction heavy equipment. And longitudinal slope should be refurbished below 14%. Earth work

volumes and each pavement quantities is indicated in the table below.

Concrete pavement work will be applied for the road surface which is more than 10% slope. Other section

surface will be aggregate pavement. The access road work will be planned to work to fulfil 6 month

construction schedule.

Table 6.1.3 Quantities of Access Road Work

Unit Quantity Excavation m3 260,000 Earth fill m3 91,000 Pavment (concrete)

m3 29,920

Pavement (Gravel)

m3 39,680

Source: JICA Survey Team

6.1.4 TEMPORARY FACILITY PLAN

(1) Concrete Plant

A batching plant with 30m3/h capacity will be planned at temporary facility yard. For the transportation of

concrete, truck mixer 5m3class:3nos, truck mixer 3m3:4nos, will be used. Aggregate and sand will be

purchased from Tarutung supplier.

Adding the batching plant, drum mixer 0.8m3class:2nos, and drum mixer 0.2m3class:4nos will be

prepared for supporting concrete work.

Source: JICA Survey Team

Figure 6.1.3 Concrete Pouring Schedule

0

50

100

150

200

250

300

0

5,000

10,000

15,000

20,000

25,000

30,000

No

v.'1

7

Dec

.'17

Jan.

'18

Feb

.'18

Mar

.'18

Ap

r.'1

8

May

'18

Jun.

'18

Jul.'

18

Aug

.'18

Sep

.'18

Oct

.'18

No

v.'1

8

Dec

.'18

Jan.

'19

Feb

.'19

Mar

.'19

Ap

r.'1

9

May

'19

Jun.

'19

Jul.'

19

Aug

.'19

Sep

.'19

Oct

.'19

No

v.'1

9

Dec

.'20

Pla

cing

vo

lime

per

day

(m3 /

day

)

Pla

cing

vo

lum

e (m

3 )

Maximum daily concrete placing volume

Average daily concrete placing volume

Accumulative concrete placing volume

Final Report

Preparatory Survey on North Sumatra Mini 6-6 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Re-bar Bending Yard

Re-bar stock yard and bending yard will be planned in temporary facility yard. All re-bar bending work

will be done in this yard and transport to each construction site.

(3) Site office and camp

Contractor’s site office and camp will be set up at temporary facility yard.

(4) Electric supply and water supply

Required electricity on site will be supplied by generator. Schedule for number of generator on site is

shown below. Water supply will be arranged at upstream of Intake and deliver to each construction site by

water truck.

Source: JICA Survey Team

Figure 6.1.4 Schedule for Number of Generator on Site

6.1.5 SPOIL BANK

Drainage during construction period should be cared adequately. Open drainage should be arranged at one

side on the spoil area when disposal work are going on. Thickness of spreading disposal material should

be 1m. Each layer should be compacted by Bulldozer. (6-8times)

If the edge of spoil bank slope is unstable, gabion mat or concrete wall should be constructed to make

stable and protect from drainage and heavy rain water. Spoil bank slope should be compacted using

backhoe bucket. After disposal work completed, drainage should be made on the spoil bank surface.

0

10

20

30

40

50

60

Nu

mb

er

15KVA

200kVA

Totalnum.

Max./month

200kVA 32 115KVA 802 54

Generator

Final Report

Preparatory Survey on North Sumatra Mini 6-7 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

6.1.6 PORING-1 MAIN CONSTRUCTION WORKS

(1) Project Road

1) Project road No, 1

Project road No, 1 is an access road from public access road to Intake. It is planned to enlarge the existing

small path. During construction period, it will be used as access to Intake and Headrace channel

construction. After construction is completed, it will be permanent access road to Intake. The

construction of Project road No, 1 will be started immediately after commencement of Poring-1 project,

the construction period is planned as 1.5months.

2) Project road No, 2

Project road No, 2 is an access road from public access road to Head Tank. During construction period, it

will be used as access to Head Tank and downstream of Headrace channel construction. After

construction is completed, it will be permanent access road to Head Tank. The construction of Project

road No, 2 will be started immediately after commencement of Poring-1 project, the construction period

is planned as 1.0months.

(2) Temporary Access Road for construction

1) Temporary Access Road No, 1

This is temporary access road from temporary facility yard to the middle point of Headrace Channel.

During construction period, it will be used as access road for excavation work and concrete work of

Headrace Cannel. The construction of Temporary Access Road No, 1 will be started immediately after

commencement of Poring-1 project, the construction period is planned as 2.0months.

2) Temporary Access Road No, 2-1,2-1,2-3

This is temporary access road from Siantar Nai-pospos village to 2 point of penstock and Powerhouse.

During construction period, it will be used as access road for excavation work and concrete work of

Penstock and Powerhouse. The construction of Temporary Access Road No, 2-1, 2-2, 2-3 will be started

immediately after commencement of Poring-1 project, the construction period is planned as 3.0months.

Final Report

Preparatory Survey on North Sumatra Mini 6-8 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 6.1.5 Layout of Project Road and Temporary Access Road

(3) Intake

1) Temporary work and excavation work

1st stage excavation work period is planned as 1.0month, and 2nd stage is 0.5month. The construction

period for diversion work is planned as 1.0month for 1st stage, and 0.5month for 2nd stage. The diversion

work should be done before excavation starting.

2) Concrete work construction period and organization

The construction work of Intake will not be a critical for the total schedule. So, the construction period

will be planned in 2018 dry season. Concrete work period is 3.5month in 1st stage, and 3month in 2nd

stage.

3) River diversion work

The construction of Intake weir and Intake will be done by 2 stage river diversion. Intake structure and left

side of Intake weir structure construction is on 1st stage. The remaining right side Intake weir structure will be

constructed on 2nd stage. Before starting excavation work of Intake and Intake Weir, River diversion work for

1st stage should be done. For excavating Intake and left side of Intake Weir area as 1st stage construction, sheet

pile wall will be constructed at middle of river. Sheet pile will be constructed from 5m upstream from Intake

weir to 5m downstream from counter dam. Upstream and downstream of the sheet pile will be connected and

filled by random material. After 1st stage concrete work is completed, up and downstream cofferdam should be

Final Report

Preparatory Survey on North Sumatra Mini 6-9 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

moved to the opposite side for 2nd stage construction work. Sheet pile will be embedded into Intake concrete

structure. The scale of diversion work has not been intended for flood conditions. Target discharge of

diversion work is estimated by the one year from construction period which is planned at maximum value

of the low flow analysis result (about Q=60m3/s). In addition, the construction status diagram is shown

in the below.

Source: JICA Survey Team

Figure 6.1.6 Figure 3.4.19 Flow Duration Curve at Poring-1 Intake Site

1st Stage River Diversion for Intake Weir 2nd Stage River Diversion for Intake Weir Source: JICA Survey Team

Figure 6.1.7 Layout of Project Road and Temporary Access Road

Final Report

Preparatory Survey on North Sumatra Mini 6-10 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

- Intake Diversion work 1st stage

The multiple-stage diversion method for the river water level by the sheet piles is determined in uniform

flow calculation water level to be added velocity head.

30.6422

2.437.641

237.641

22

gg

vWL

Source: JICA Survey Team

Figure 6.1.8 Typical Section of Diversion Work 1st Stage

- Intake Diversion work 2nd stage

Diversion work of 2nd stage is used the Intake and Sand flash. The water level of diversion work for

target discharge (Q = 60m3/s) is EL.646.92. In this case are became overflow of intake weir spillway.

Drainage capacity of the diversion work of 2nd stage is shown in the below.

- Drainage capacity of Sand flash only : Q = 25.30m3/s

- Do not overflow the Intake weir of spillway: Q = 53.3m3/s

Each facilities of discharge (sand land sand elimination gate, sediment ejection, water through the water

intake weir) are as shown in Figure 6.1.10. In addition, case of target discharge (60m3/s) will be shown in

the following formula.

Q4(Target discharge of diversion work) = Q1 (35.36) + Q2 (20.20) + Q3 (4.44) = 60m3/s.

Source: JICA Survey Team

Figure 6.1.9 Typical Section of Diversion Work 2nd Stage

Design Slope i=1/ 50.0Roughness Module n= 0.035Design Discharge Q=60m3/sWater Depth hw=1.76mVelocity V=4.20m/sMinimum Riverbed E.L 639.61Water Level E.L 641.37

Q1(Sand drain) Q2

(Sand trap basin)

Q3(Weir crerst)

Final Report

Preparatory Survey on North Sumatra Mini 6-11 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Source: JICA Survey Team

Figure 6.1.10 Drainage Capacity of Diversion Work 2nd Stage

(4) Headrace Channel

1) Temporary work and excavation work

For stating the excavation work of Headrace Channel, it is required to complete the construction of

Project road No, 1 and 2. The excavation of Headrace channel will be started at 2nd month from project

commencement. The period of Headrace Channel excavation is 7.3months.

2) Concrete work construction period and organization

Concrete work will be started after 6.5months from the commencement of excavation. Total working

period of concrete work is 14months. Only top slab concrete work is expected in last 2.5 months. For

the construction of Box type culvert, the construction of U-Type will be ahead and top slab work will be

followed. In this schedule, top slab work will be started after 3month from U-type culvert construction.

3) Headrace Channel construction cycle time

1Block is 6m. The period for U-type culvert construction of 1 block is 8days. (4days for basement, 4days

for wall) Top slab construction period for 1 block is 5days.

(5) Head Tank

1) Temporary work and excavation work

The excavation work of Head Tank will be carried out immediately after Project road No, 2completed. It

will be started after 1month from commencement of project, it will take 0.8month. The concrete work

for Head Tank will be delayed 3 month for prioritizing Headrace Channel and Penstock excavation work.

2) Concrete work construction period and organization

Concrete work start at 5th month from commencement of project. Construction period is 2.5month.

(m3/s)Q1 35.36Q2 20.20Q3 4.44Q4 60.00

Final Report

Preparatory Survey on North Sumatra Mini 6-12 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(6) Penstock

1) Temporary work and excavation work

For Penstock excavation work, it is required to complete Project road No, 2 and Temporary Access Road

No, 2-1, 2-1, 2-3. Penstock excavation work will start 4months after commencement of project. The

period of Penstock excavation is 6.0months.

2) Concrete work construction period and organization

Masonry work will start before concrete work, after 2 months from commencement of excavation work.

Masonry work will follow the section which the excavation work is completed. Construction period of

Masonry work is 5.5 months. Concrete work will start after 5 months from commencement of

excavation work. Construction period is 9.0 months.

3) Penstock construction cycle time

For Anchor block basement, 1st lift is 8 days, 2nd and 3rd lift is 6 days. Secondary concrete, after pipe

install, 1st, 2nd and 3rd lift id 6 days. For saddle support basement, 1st lift is 6days. 2nd lift is 4days.

Secondary concrete, after pipe install, is 3days.

(7) Powerhouse

1) Temporary work and excavation work

Temporary Access Road No, 2-3 will be used as access road to powerhouse at early stage. This temporary

access will be mainly used for hauling the excavated material from Penstock. After completing Poring2

Headrace channel excavation, access road along Poring2 Headrace channel will be an access road to

Powerhouse. Excavation work for powerhouse will be started after completion of Penstock excavation

and certain progress of Penstock pipe installation. (14.8months form commencement of project)

The period of excavation is 1.3months. The excavation equipment is Backhoe 1no, Bulldozer 1no, and

11tDump Truck 4nos.

2) Concrete work construction period and organization

Concrete work for Powerhouse will be started after completion of Intake concrete work. Concrete work

period is 2.0month in 1st stage, and 0.5month in 2nd stage (Secondary concrete).

3) Building work and M & E work

Following concrete work, 1.5month is scheduled for Building work including roof work and M&E work.

Then, after installation of Turbine and Generator, 1month is scheduled for Building finishing work.

4) Turbine and Generator

- Draft tube：Installation of Draft tube no1 will be started 19.5month after the commencement of

Pring1 project. Draft tube no2 will be started 0.5month after Draft tube No1.

- Turbine and Generator：Installation of Turbine No1 will be started 20.5month after the

commencement of Pring1 project. Turbine no2 will be started 0.5month after Turbine No1.

Final Report

Preparatory Survey on North Sumatra Mini 6-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Installation of Generator No1 will be started 20.8month after the commencement of Pring1

project. Generator no2 will be started 0.5month after Generator No1.

- Main transformer ： Installation of main transformer will be started 20month after the

commencement of Pring1 project.

- Support and control equipment：Installation of support equipment for Turbine will be done

following Turbine installation. Support and control equipment of Generator will be started after

the completion of installation for Generator No1 & No2. There will be various sensitive works,

such setting up the cable, adjustment of equipment, detail cabling works, etc.

- Dry and wet test：Dry test is scheduled 23month after the commencement of Pring1 project and

the test period will be 0.5month. After dry test, Wet test will be carried out continuously. It will

also take 0.5month. Commercial operation will be started after the completion of Wet test

including full load test.

6.1.7 PORING-2 MAIN CONSTRUCTION WORKS

The commencement of Poring-2 project will be 8months after the commencement of Poring-1.

(1) Project road

1) Project road No, 3

Project road No, 3 is an access road from Siantar Nai-pospos Village to the middle point of Headrace

channel. During construction period, it will be used as access to Headrace channel construction. After

construction is completed, it will be permanent access road to Powerhouse No1 and Headrace channel

upstream. The construction of Project road No, 3 will be started immediately after commencement of

Poring-2 project, the construction period is planned as 1month.

2) Project road No, 4

Project road No, 4 is an access road from public access road to Powerhouse. During construction period,

it will be used as access to Penstock and Powerhouse for excavation and concrete works. After

construction is completed, it will be permanent access road to Powerhouse. The construction of Project

road No, 4 will be started immediately after commencement of Poring-2 project, the construction period

is planned as 4.5 months.

(2) Temporary Access Road for construction

1) Temporary Access Road 3-1, 3-2

This is temporary access road from Project road No, 4 to 2 point of Penstock. During construction period,

it will be used as access road for excavation work and concrete work of Penstock. The construction of

Temporary Access Road No, 3-1, 3-2 will be started 1month after commencement of Project road No, 4,

the construction period is planned as 2.0months.

Final Report

Preparatory Survey on North Sumatra Mini 6-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(3) Headrace Channel

1) Temporary work and excavation work

For stating the excavation work of Headrace Channel, it is required to complete the construction of

Project road No, 3. The excavation of Headrace channel will be started 1month after the commencement

of Project road No, 3. Temporary Access Road No, 2-3 is necessary for starting excavation. The period of

Headrace Channel excavation is 7.5months.

2) Concrete work construction period and organization

Concrete work will be started after 7months from the commencement of excavation. Total working period

of concrete work is 14.5months. Only top slab concrete work is expected in last 1.5 months. For the

construction of Box type culvert, the construction of U-Type will be ahead and top slab work will be

followed. In this schedule, top slab work will be started after 3month from U-type culvert construction.

3) Headrace Channel construction cycle time

1Block is 6m. The period for U-type culvert construction of 1 block is 8days. (4days for basement, 4days

for wall) Top slab construction period for 1 block is 5days.

(4) Head Tank

1) Temporary work and excavation work

The excavation work of Head Tank will be carried out 2.5month after starting excavation of Headrace

channel from Public access road. The period of excavation will be 0.5month. The concrete work for

Head Tank will be delayed 3 month for prioritizing Headrace Channel and Penstock excavation work.

2) Concrete work construction period and organization

Concrete work start at 6th month from commencement of Poring2 project. Construction period is

2.5month.

(5) Penstock

1) Temporary work and excavation work

For Penstock excavation work, it is required to complete Project road No, 4 and Temporary Access Road

No, 3-1, 3-2. Penstock excavation work will start 3months after commencement of Poring2 project.

The period of Penstock excavation is 8.0months.

2) Concrete work construction period and organization

Masonry work will start before concrete work, after 3 months from commencement of excavation work.

Masonry work will follow the section which the excavation work is completed. Construction period of

Masonry work is 7.0 months. Concrete work will start after 6 months from commencement of excavation

work. Construction period is 13 months.

Final Report

Preparatory Survey on North Sumatra Mini 6-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

3) Penstock construction cycle time

For Anchor block basement, 1st lift is 8 days, 2nd and 3rd lift is 6 days. Secondary concrete, after pipe

install, 1st, 2nd and 3rd lift id 6 days. For saddle support basement, 1st lift is 6days. 2nd lift is 4days.

Secondary concrete, after pipe install, is 3days.

(6) Powerhouse

1) Temporary work and excavation work

Project road No, 4 will be used as access road to powerhouse. Excavation work for powerhouse will be

started after completion of Penstock excavation and certain progress of Penstock pipe installation.

(16month form commencement of Poring2 project) The period of excavation is 2.0months.

2) Concrete work construction period and organization

Concrete work period is 2.0month in 1st stage, and 0.5month in 2nd stage (Secondary concrete).

3) Building work and M & E work

Following concrete work, 1.5month is scheduled for Building work including roof work and M&E work.

Then, after installation of Turbine and Generator, 1month is scheduled for Building finishing work.

4) Turbine and Generator

- Draft tube：Installation of Draft tube no1 will be started 21.5month after the commencement of

Pring2 project. Draft tube no2 will be started 0.5month after Draft tube No1.

- Turbine and Generator：Installation of Turbine No1 will be started 22.5month after the

commencement of Pring2 project. Turbine no2 will be started 0.5month after Turbine No1.

Installation of Generator No1 will be started 22.8month after the commencement of Pring2

project. Generator no2 will be started 0.5month after Generator No1.

- Main transformer：Installation of main transformer will be started 22.0 month after the

commencement of Pring2 project.

- Support and control equipment：Installation of support equipment for Turbine will be done

following Turbine installation. Support and control equipment of Generator will be started after

the completion of installation for Generator No1 & No2. There will be various sensitive works,

such setting up the cable, adjustment of equipment, detail cabling works, etc.

- Dry and wet test：Dry test is scheduled 24month after the commencement of Pring2 project and

the test period will be 0.5month. After dry test, Wet test will be carried out continuously. It will

also take 0.5month. Commercial operation will be started after the completion of Wet test

including full load test.

Final Report

Preparatory Survey on North Sumatra Mini 6-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(Blank Page)

Final Report

Preparatory Survey on North Sumatra Mini 7-1 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

CHAPTER 7 NATURAL AND SOCIAL ENVIRONMENTAL CONSIDERATION

7.1 PROJECT COMPONENTS WITH POTENTIAL IMPACTS ON THE ENVIRONMENT

The project comprises of two main components, i.e., Construction of the Poring-1 and Poring-2 Mini

Hydropower Plants (Component 1: Hydropower Plants) and Construction of the Poring-1 and Poring-2

Transmission Line (Component 2: Transmission Lines).

The facilities in Component 1: Hydropower Plants and Component 2: Transmission Lines are shown in

Table 7.1.1.

Table 7.1.1 Project Component Component 1: Hydropower Plants Facilities Area (ha)Poring-1 Intake Weir 0.55

Access Road (Existing road to intake weir including improvement of existing road and new road)

3.18

Access Road (Head tank to existing road) 0.59Headrace Channel and Project Road along Headrace Channel 5.26Head Tank 0.2Penstock 1.07Powerhouse 0.3Spoil Bank 1 2.16Spoil Bank 2 0.53Spoil Bank 3 1.10Spoil Bank 4 0.53Spoil Bank 5 0.18Spoil Bank 6 0.98Contractor’s Facility 3.5Subtotal 20.13

Poring-2 Access Road (Existing road to headrace channel) 0.2Access Road (Existing road to powerhouse) 3Headrace Channel 5.37Head Tank 0.12Penstock 2.53Powerhouse 0.3Spoil Bank 7 0.95Spoil Bank 8 0.51Spoil Bank 9 0.15Spoil Bank 10 0.56Spoil Bank 11 0.19Spoil Bank 12 3.81Spoil Bank 13 0.37Spoil Bank 14 0.92Spoil Bank 15 1.1Subtotal 20.08

Total 40.21

Final Report

Preparatory Survey on North Sumatra Mini 7-2 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Component 2: Transmission Lines Facilities Area (ha) Poring-1 33.8 km transmission line from powerhouse to

Tarutung Substation 0.149

(1 m² x 1,487 including poles and guy wire)Poring-2 36.7 km transmission line from powerhouse to

Tarutung Substation 0.162

(1 m² x 1,615 including poles and guy wire)Substation for Poring-1 and Poring-2 0.073

(13 m x 56 m)Total 0.384Source: JICA Survey Team

7.2 PRESENT CONDITIONS IN THE PROJECT AREA

7.2.1 NATURAL ENVIRONMENT

(1) Temperature

The project is located in the North Sumatra area, which has a tropical climate. The warm water

surrounding the island sets a fairly constant temperature with little seasonal variation. The average

maximum temperature ranges from 24°C to 26°C and the average minimum temperature ranges from

15°C to 16°C. There is no drastic seasonal difference; however, the rainy reason starts from May to July

and restarts from November to January. The dry season starts from February to April and restarts from

August to October. Maximum and minimum temperatures in North Sumatra between 2010 and 2014 are

shown in Figure 7.2.1 and Table 7.2.1.

Source: Meteorology, Climatology and Geophysics Agency (BMKG)

Figure 7.2.1 Maximum and Minimum Temperatures in North Sumatra

15.0

17.0

19.0

21.0

23.0

25.0

27.0

29.0

1 2 3 4 5 6 7 8 9 10 11 12

20102011201220132014Ave Max20102011201220132014Ave Min

℃ Month

Final Report

Preparatory Survey on North Sumatra Mini 7-3 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.1 Maximum and Minimum Temperatures in North Sumatra Year JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

2010 24.9 25.7 25.5 25.4 26.3 25.4 25.1 25.5 25.4 25.1 24.2 24.9

2011 26.0 26.3 26.4 26.4 26.6 26.1 25.7 25.7 25.6 25.5 25.4 25.6

2012 25.2 24.9 25.2 25.0 25.8 25.1 24.9 24.3 24.4 24.0 23.9 22.8

2013 25.6 24.4 24.9 24.8 25.0 25.3 24.9 25.1 25.4 24.6 24.6 24.0

2014 26.0 26.3 26.2 28.6 26.6 26.0 25.7 25.6 25.5 25.4 25.3 25.4

Ave. Max 25.5 25.5 25.6 26.0 26.1 25.6 25.3 25.2 25.3 24.9 24.7 24.5

2010 17.5 17.3 17.5 17.1 17.3 17.6 16.8 16.1 17.2 16.2 17.8 17.0

2011 15.3 15.5 15.6 15.5 15.6 15.4 15.2 15.1 15.6 15.6 15.6 15.2

2012 16.6 17.2 16.6 17.0 16.3 17.2 16.5 16.8 16.7 15.5 15.5 15.2

2013 17.0 17.2 15.7 15.6 16.4 16.5 16.2 16.8 16.8 17.4 17.6 15.2

2014 15.4 15.6 15.7 15.6 15.6 15.5 15.3 15.1 15.7 15.5 15.5 15.2

Ave. Min 16.4 16.6 16.2 16.2 16.2 16.4 16.0 16.0 16.4 16.0 16.4 15.6 Source: Meteorology, Climatology and Geophysics Agency (BMKG)

(2) Protected Area

In Indonesia, there are 50 national parks of which 11 national parks are located in Sumatra Island. There

are two national parks, i.e., Gunung Leuser (about 270 km north from the project area) and Batan Gadis

(about 135 km south from the project area), in the North Sumatra Province; however, they are located far

from the project area. It was confirmed that there is no protected area around and in the project area.

The location of the two national parks and the project area is shown in Figure 7.2.2.

Source: JICA Survey Team

Figure 7.2.2 National Park in Sumatra Island

(3) Fauna and Flora

The result of the field survey and hearing with local authorities and villagers on fauna and flora in the

project area is shown in Chapter 7.6.2.

Project Location

Final Report

Preparatory Survey on North Sumatra Mini 7-4 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(4) Land Usage

Most of the project area is located in the area categorized as production forest whose main function is to

yield forest produces. The proposed locations for constructing the facilities of the mini hydropower plants

of Poring-1 and Poring-2 are currently used for tree plantation such as rubber tree. There is no residential

area affected by the project. The proposed locations for constructing the transmission lines for the

Poring-1 Mini Hydropower Plant and Poring-2 Mini Hydropower Plant are partly in the production forest

area used for plantation such as rubber trees and the rest of the land is used as agricultural land. There is

no residential area affected by the construction of transmission lines. Land usage map around the project

area is shown in Figure 7.2.3.

Source: Forest Usage Map, Ministry of Forestry, 2014

Figure 7.2.3 Land Usage

Sumatra Island

Project Area

: Project Area

: Protected Forest

: Limited Production Forest

: Permanent Production Forest

Final Report

Preparatory Survey on North Sumatra Mini 7-5 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

7.2.2 SOCIAL ENVIRONMENT

(1) Population, Demography and Religion

There are two villages in Component 1. In these villages, all residents belong to the Toba Batak ethnic

group and speak Batak as their mother tongue. Most of the villagers are Christians with few Muslims.

There are 11 villages in Component 2. In these villages, the Toba Batak ethnic group is dominant ranging

from 80% in Siraja Hutagalung Village to 100% in the villages of Siantar Naipospos, Pardomuan Nauli,

Pansurbatu 1, Pansurbatu 2, and Hatatoruan 1. As minor ethnic groups, Nias, Jawa, Minan, Patang,

Madailing, and Aceh were identified. The Toba Batak is a dominant subgroup of the Batak ethnic group.

The Batak ethnic group is the third biggest ethnic group in Indonesia with about 8.4 million people spread

all over Indonesia. In North Sumatra Province, the Toba Batak is the major ethnic group.

Batak is the major language in all surveyed villages. Indonesian is fairly popular in Simonagkir Julu

Village (40%) which is the closest to Tarutung Substation and in the villages of Parbubu 1 (35%) and

Siraja Hutagalung (35%) which are located next to Simonagkir Julu Village. Otherwise, all surveyed

villages speak Batak. Christianity is dominant in all surveyed villages ranging from 82% to 100%.

Population, ethnicity, language, and religion in all surveyed villages are shown in Table 7.2.2.

Table 7.2.2 Population, Ethnicity, Language, and Religion Component 1: Hydropower Plants Village Population

(Female) Households Ethnicity Language Religion

Siantar Naipospos 1,083 (500) 217 Toba Batak (100%) Batak (100%) Christian (98.6%) Muslim (1.4%)

Pardomuan Nauli 732 (400) 154 Toba Batak (100%) Batak (100%) Christian (100%) Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Population Households Ethnicity Language Religion Siantar Naipospos 1,083 (495) 217 Toba Batak (100%) Batak (100%) Christian (98.6%)

Muslim (1.4%) Pardomuan Nauli 732 (385) 154 Toba Batak (100%) Batak (100%) Christian (100%) Pansurbatu 953 (420) 168 Toba Batak (99%)

Nias, Mandailing (angkola) (1%) Batak (99%) Indonesia (1%)

Christian (100%)

Pansurbatu 2 320 (120) 60 Toba Batak (100%) Batak (99%) Indonesia (1%)

Christian (100%)

Hutatoruan VIII (Aek Nasia)

485 (260) 114 Toba Batak (99%) Nias, Simalungun (1%)

Batak (99%) Indonesia (1%)

Christian (100%)

Aek Sian Simun 1,324 (675) 309 Toba Batak (99%) Nias, Simalungun (1%)

Batak (99%) Indonesia (1%)

Christian (99.9%) Muslim (0,1%)

Hutatoruan III* 520 (220) 75 Toba Batak (99%) Jawa (1%)

Batak (85%) Indonesia (15%)

Christian (99.9%) Muslim (0.1%)

Parbubu I 1,200 (750) 286 Toba Batak (95%) Nias, Jawa (5%)

Batak (65%) Indonesia (35%)

Christian (99,9%) Muslim (0.1%)

Hutatoruan I 1,771 (897) 434 Toba Batak (100%) Batak (95%) Indonesia (5%)

Christian (99%) Muslim (1%)

Siraja Hutagalung 2,265 (1,245) 617 Toba Batak (80%) Nias, Minang, Jawa (20%)

Batak (65%) Indonesia (35%)

Christian (82%) Muslim (18%)

Simorangkir Julu 1,133 (603) 279 Toba Batak (85%) Nias, Padang, Aceh, Jawa, Mandailing (15%)

Batak (60%) Indonesia (40%)

Christian (99%) Muslim (1%)

Source: Hearing with Acting Village Heads in July 2015

Final Report

Preparatory Survey on North Sumatra Mini 7-6 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(2) Economic Status

1) Income

Income in the two surveyed villages of Component 1 is very low. It is considered that villagers in these

two villages live in self-sufficiency. In other words, income is mainly or only generated from plantation.

Other necessities such as food and fire wood are grown in their land and purveyed by themselves without

cash. The average income of the affected households (AHHs) is relatively higher than that of the two

villages. However, it is still under the average income per capita per year of North Sumatra Province.

Most of the main income is generated from plantation of AHHs.

Average income per capita per year in the surveyed villages of Component 2 ranges from Rp2,019,672 to

Rp6,000,000. All villages are below the average income in North Sumatra Province. There is a tendency

that the closer the village to the center of Tarutung City, the higher the income. Main income in the

villages of Component 2 is generated from agricultural sector ranging from 70% in Sijara Hutagalung

Village to 93% in Siantar Naipospos Village and Pardomuan Nauli Village. Income from plantation is

dominant in the villages located in the mountainous area. On the other hand, the ratio of income from

lowland rice cultivation is high among the villages located in the flat land including the villages of

Hutatoruan III, Parbubu 1, Hutatoruan 1, Siaraja Hutagalung, and Simorangkir Julu. Income in the project

area is shown in Table 7.2.3. Main income source in the project area is shown in Table 7.2.4.

Table 7.2.3 Income Component 1: Hydropower Plants

Village Average Income per Capita per

Year (Rp) Average per Poorest Income

per Year (Rp) Average per Wealthiest Income per Year (Rp)

North Sumatra Province 38,050,000* 3,749,916* N/ASiantar Naipospos 2,404,432 1,200,000 19,200,000Pardomuan Nauli 2,019,672 960,000 9,600,000Affected Households (AHHs)1 5,234,575 1,200,000 19,600,000Source:*Central Bureau of Statistics in North Sumatra Province, 2014, Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Average Income per Capita

per Year (Rp) Average per Poorest Income

per Year (Rp) Average per Wealthiest Income per Year (Rp)

Siantar Naipospos 2,404,432 1,200,000 19,200,000Pardomuan Nauli 2,019,672 960,000 9,600,000Pansurbatu 2,115,424 1,500,000 9,000,000Pansurbatu 2 2,250,000 2,100,000 9,000,000Hutatoruan VIII (Aek Nasia) 3,384,742 2,400,000 9,000,000Aek Sian Simun 3,080,664 2,100,000 15,000,000Hutatoruan III* 2,596,153 1,500,000 12,000,000Parbubu I 4,290,000 2,400,000 39,000,000Hutatoruan I 6,000,000 1,800,000 30,000,000Siraja Hutagalung 4,903,311 2,400,000 45,000,000Simorangkir Julu 5,023,477 3,000,000 24,000,000AHHs2 N/A N/A N/A Source: Central Bureau of Statistics in North Sumatra Province, 2014, Hearing with Acting Village Heads in July 2015

1 As for Component 1, 43 households were identified as affected households in which 32 households were interviewed. The remaining 11 households could not be reached as they are living outside the project area, which is under land dispute 2 As for Component 2, 431 households were identified within the area of 3 m width x proposed transmission line length (about 32 km). Among the 431 households, 175 households were interviewed. The remaining 256 could not be reached mainly as they are living outside the project area

Final Report

Preparatory Survey on North Sumatra Mini 7-7 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.4 Main Income Source Component 1: Hydropower Plants (%)

Vil

lage

Agriculture

Smal

l-sc

ale

Tra

ding

(S

hops

, Sta

lls)

Tra

nspo

rtat

ion

(Mot

orcy

cle,

Tax

i)

Gov

ernm

ent S

ervi

ce

Fac

tory

Wor

k

Lab

orin

g

Oth

ers

Tota

l

Low

land

Ric

e C

ulti

vati

on

Upl

and

Ric

e C

ulti

vati

on

Low

land

Veg

etab

le

Cul

tiva

tion

Upl

and

Veg

etab

le

Cul

tiva

tion

Pla

ntat

ion

SN 93 2 0 0 5 86 2 2 0.5 0 0 2.3PN 93 2 0 0 20 71 2 2 0.5 0 0 2.5AHHs 87.5 0 0 0 0 87.5 6.25 0 0 0 0 6.25SN: Siantar Nipospos Village, PN: Pardomuan Nauli Village Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines (%)

Vil

lage

Agriculture

Smal

l-sc

ale

Tra

ding

(S

hops

, Sta

lls)

Tra

nspo

rtat

ion

(Mot

orcy

cle,

Tax

i)

Gov

ernm

ent S

ervi

ce

Fac

tory

Wor

k

Lab

orin

g

Han

dicr

aft3

Oth

ers

Tota

l

Low

land

Ric

e C

ulti

vati

on

Upl

and

Ric

e C

ulti

vati

on

Low

land

Veg

etab

leC

ulti

vati

on

Upl

and

Veg

etab

le

Cul

tiva

tion

Pla

ntat

ion

SN 93 2 0 0 5 86 2 2 0.5 0 0 0 2.3PN 93 2 0 0 20 71 2 2 0.5 0 0 0 2.5PB 84 38 0 0 10 36 3 1 5 0 4 2 1PB1 92 40 0 1 3 48 5 1 1 0 0 1 0PB2 90 40 0 2 3 45 1 1 3 0 0 5 0HT VIII 72.5 27.5 0 2 3 40 1 0.5 1 0 0 25 0ASS 85 42 0 5 0 38 2 1 5 0 0 7 0HTIII 80 60 0 2 3 15 4.5 0.5 10 0 0 5 0PRB I 70 55 0 0 3 12 2 3 10 0 0 15 0HT I 75 62 0 3 0 10 5 5 13 0 0 0 2SHG 72 65 0 0 2 5 5 1 20 0 0 5 0SMJ 80 60 0 0 3 17 1.5 1 2.5 0 0 5 0AHHs* - - - - - - - - - - - - - SN: Siantar Nipospos Village, PN: Pardomuan Nauli Village, PB:Pansurbatu Village, PB1:Pansurbatu 1 Village, PB2:Pansurbatu 2 Village, HT VIII: Hutatoruan VIII (Aek Nasia) Village, ASS: Aek Sia Simun Village, HT III: Hutatoruan III, PRB I: Parbubu I Village, HT I: Hutatoruan I Village, SHG: Siraja Hutagalung Village, SMJ: Simorangkir Julu Village Source: Hearing with Acting Village Heads in July 2015

2) Vulnerable

The minimum wage of North Sumatra Province in 2015 is set at Rp1,653,000 per month or

Rp198,360,000 per year. In Component 1, about half of the affected households in Siantar Naipospos

Village and most of the affected households in Pardomuan Nauli Village have fallen into the category of

vulnerable. As mentioned in the section on income, unlike city dwellers, villagers in the project area are

self-sufficient in food which does not require much money. Accordingly, justification of vulnerability in

each affected household needs to take not only income but also assets into account.

In Component 2, large numbers of affected households are under the category of vulnerable households

ranging from 33% to 92%. The number of vulnerable is small near Tarutung City.

3Some women make a traditional shawl; local name is ulos. They weave it in their home using a traditional technique.

Final Report

Preparatory Survey on North Sumatra Mini 7-8 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The number of vulnerable among the affected households is shown in Table 7.2.5.

Table 7.2.5 Vulnerable Households in Total Affected Households Component 1: Hydropower Plants

Village Vulnerable Households (in Total Interviewed Affected Households) Siantar Naipospos Village 11 (26 or 42%) Pardomuan Nauli Village 5 (6 or 83%)

Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Vulnerable Households (in 175 Interviewed Affected Households) Siantar Naipospos 29 (39 or 74%) Pardomuan Nauli 57 (62 or 92%) Pansurbatu 26 (32 or 81%) Pansurbatu 2 - Hutatoruan VIII (Aek Nasia) 10 (10 or 100%) Aek Sian Simun 2 (2 or 100%) Hutatoruan III* 3 (4 or 75%) Parbubu I 2 (2 or 100%) Hutatoruan I 1 (3 or 33%) Siraja Hutagalung 6 (11 or 55%) Simorangkir Julu 5 (10 or 50%) Source: Hearing with Acting Village Heads in July 2015

(3) Agriculture Production

1) Rice Production

In the two surveyed villages of Component 1, rice is planted in wet land and dry land. Rice paddy is fed

with irrigation using spring water or rain. The cropping season for rice paddy is once in a year starting

from October/November to January/February. In between crop season, the rice paddy is used for growing

vegetables. As for upland rice, the cropping season is also once in a year starting from July/August to

November/December. Upland rice is intercropped in the plantation area together with other vegetables.

The rate of irrigated/rainfed rice and upland rice is almost the same in Siantar Naipospos Village. On the

other hand, irrigated/rainfed is largely applied (84%) in Pardomuan Nauli Village.

In the surveyed villages in Component 2, the irrigated/rainfed paddy in total village land ranges from

0.3% in Siantar Naipospos Village to 64.6% in Siraja Hutagalung Village.

Rice production in the surveyed villages is shown in Table 7.2.6.

Final Report

Preparatory Survey on North Sumatra Mini 7-9 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.6 Rice Production Component 1: Hydropower Plants

Village Total Area

(ha) Rice Production Area in

Total Agricultural Land (%)

Rice Production Area

Irrigated/Rainfed Paddy Area (%)

Irrigated/ Rainfed Paddy

Yield (ton/ha/year)

Upland Rice Area (%)

Upland Rice Yield

(ton/ha/year)

Siantar Naipospos

3,968 0.6% (Total Agricultural Land is 23 ha)

0.3 5.6 0.3 3.1

Pardomuan Nauli

4,800 1.94% (Total Agricultural Land is 92 ha)

1.6 5.6 0.3 3.1

Source: Hearing with Acting Village Heads in April 2015

Component 2: Transmission Lines

District Village Total Area (ha)

Rice Production Area in Total Agricultural

Land (%)

Rice Production Area

Irrigated/Rainfed Paddy Area (%)

Irrigated/ Rainfed Paddy

Yield (ton/ha/year)

Upland Rice Area (%)

Upland Rice Yield

(ton/ha/year)

Adian Koting

Siantar Naipospos

3,968 0.6 0.3 (13 ha) 5.6 0.3 (10 ha) 3.1

Pardomuan Nauli

4,800 1.94 1.6 (77 ha) 5.6 0.3 (15 ha) 3.1

Pansurbatu 3,642 N/A 1.9% (139 ha)* *the ratio of irrigated/ rainfed paddy area in three villages, Pansurbatu, Pansurbatu 1, and Pansurbatu 2 (7,283 ha)

5.72** N/A

3.06**

Pansurbatu 2 2,427 N/A N/A

Tarutung Hutatoruan VIII (Aek Nasia)

350 N/A 6.85% (24 ha) 5.65** N/A 3.22**

Aek Sian Simun 456 N/A 5.26% (24 ha) N/A Hutatoruan III 44 N/A 11.36% (5 ha) N/A Parbubu I 475 N/A 15 % (71 ha) N/A Hutatoruan I 200 N/A 26 % (56 ha) N/A

Siatas Barita

Siraja Hutagalung

195 N/A 64.6 % (126 ha) 5.67** N/A 3.22**

Simorangkir Julu

300 N/A 11% (33 ha) N/A

* BPS (Central Bureau of Statistics) Kecamatan Adian Koting Dalam Angka 2014. **Data at District Level in BPS (Central Bureau of Statistics) Kecamatan Adian Koting Dalam Angka 2014. Source: Hearing with Acting Village Heads in July 2015, BPS (Central Bureau of Statistics) Kecamatan Adian Koting Dalam Angka 2014. Source: Hearing with Acting Village Heads in July 2015, BPS (Central Bureau of Statistics) Kecamatan Adian Koting Dalam Angka 2014.

2) Rice Sufficiency

In the two surveyed villages of Component 1, cultivated rice for domestic consumption can last for nine

months to three months. The AHHs can grow rice lasting from six months to nine months (44%) followed

by nine months to 12 months (38%), and for three months to six months (19%). Rice shortage can be

managed by buying at the market as the first choice followed by receiving governmental assistance and

offering labor in exchange of getting rice from other villagers.

In the surveyed villages of Component 2, ratio of rice sufficiency is high among the villages located in

flat land in which lowland rice cultivation is popular. In particular, about 80% of households can grow

rice lasting for nine months to 12 months in the villages of Siraja Hutagalung and Simorangkir Julu.

Similar to Component 1, rice shortage can be managed by buying at the market as the first choice

followed by receiving governmental assistance in the surveyed villages of Component 2.

Final Report

Preparatory Survey on North Sumatra Mini 7-10 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Rice sufficiency in the surveyed villages is shown in Table 7.2.7. Rice shortage management in the

surveyed villages is shown in Table 7.2.8.

Table 7.2.7 Rice Sufficiency Component 1 Hydropower Plants HHs with Rice All

Year (%) HHs with Rice for 9-12 Months (%)

HHs with Rice for 6-9 Months (%)

HHs with Rice for 3-6 Months (%)

Siantar Naipospos Village 0 2 45 53Pardomuan Nauli Village 0 4 60 36AHHs (32 HHs) 0 37.5 43.75 18.75Source: Hearing with Acting Village Heads in April 2015

Component 2 Transmission Lines HHs with Rice All

Year (%) HHs with Rice for 9-12 Months (%)

HHs with Rice for 6-9 Months (%)

HHs with Rice for 3-6 Months (%)

Siantar Naipospos 0 2 45 53Pardomuan Nauli 0 4 60 36Pansurbatu 0 15 75 10Pansurbatu 2 0 10 75 15Hutatoruan VIII (Aek Nasia) 0 3 72 25Aek Sian Simun 1 5 60 34Hutatoruan III 1 50 34 15Parbubu I 1 50 39 10Hutatoruan I 2 - - - Siraja Hutagalung 2 80 13 5

Simorangkir Julu 2 75 18 5AHHs 1.7 13 32 53Source: Hearing with Acting Village Heads in July 2015

Table 7.2.8 Rice Shortage Management (Ranking) Component 1: Hydropower Plants

Buy Trade/

ExchangeCharitable Donation

from Community Governmental/

International Aid Labor for Another

Household Siantar Naipospos Village 1 - - 2 3 Pardomuan Nauli Village 1 - - 2 3 AHHs 1 - - 2 - Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Buy Trade/

ExchangeCharitable Donation

from Community Governmental/

International Aid Labor for Another

Household Siantar Naipospos 1 - - 2 3 Pardomuan Nauli 1 - - 2 3 Pansurbatu 1 - - 2 - Pansurbatu 2 1 - - 2 - Hutatoruan VIII (Aek Nasia) 1 - - 2 - Aek Sian Simun 1 - - 2 - Hutatoruan III 1 - - 2 - Parbubu I 1 - - 2 - Hutatoruan I 1 - - 2 - Siraja Hutagalung 1 - - 2 - Simorangkir Julu 1 - - 2 - AHHs 1 - - 2 - Source: Hearing with Acting Village Heads in July 2015

3) Plantation

In the two surveyed villages of Component 1, except in the residential area, villagers use whole forest

land for commercial tree plantation as well as dry-field farming. Vegetables such as stink-bean, fruits

such as durian, mango, and upland rice are intercropped in the plantation area. Rubber and meranti trees

Final Report

Preparatory Survey on North Sumatra Mini 7-11 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

are the dominant species in Siantar Naipospos Village. On the other hand, rubber and benzoin trees are

the dominant species in Pardomuan Nauli Village.

Type of trees and the area for plantation in the surveyed villages in Component 1 are shown in Table

7.2.9. As for Component 2, there is no data available at the village level.

Table 7.2.9 Type of Trees and Area for Plantation (ha) Component 1: Hydropower Plants

Village Rubber Palm Hairy Fruit

Frankincense /Benzoin

Kyuhutan /Meranti

Others (with intercropping/mix cropping system) Coffee, Cacao, Coconut, Durian, Duku, Rambai,

House Mango, Stink-bean, Kiwi, Jackfruit Siantar Naipospos 200 1 2 2 100-200 100-200 Pardomuan Nauli 200 0.5 0.5 100 50 100-150 Source: Hearing with Acting Village Heads in April 2015

(4) Education

1) Literacy

In the two surveyed villages of Component 1, the villagers use Batak language for communication and

Indonesian language as the second language. The literacy rate (able to read and write at daily life level in

Indonesia) is 60% and the rate of speaking Indonesian is about 80%. Only 10% of the villagers including

AHHs are able to understand official documents written in Indonesian. Although the literacy rate is nearly

100% in most of the surveyed villages of Component 2, the ratio of understanding official document

written in Indonesian remains low at about 10%. As for the AHHs, the ratio of understating official

document written in Indonesian is slightly higher at 28.5%, but it still remains low. Accordingly, it is

necessary to give considerations such as assigning a staff who is bilingual in Indonesian and Batak

language whenever there is an occasion to communicate with the villagers.

Literacy rate of the surveyed villages is shown in Table 7.2.10.

Final Report

Preparatory Survey on North Sumatra Mini 7-12 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.10 Literacy Rate Component 1: Hydropower Plants

Village Literacy (able to read and

write at daily life level) (%)

Reading/Writing Understanding Official Document

Written in Indonesian (%) Speaking (%)

Siantar Naipospos Village 60 10 80 Pardomuan Nauli Village 60 10 80 AHHs 90.6 9.4 87.5 Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Literacy (able to read and

write at daily life level) (%)

Reading/Writing Understanding Official Document

Written in Indonesian (%) Speaking (%)

Siantar Naipospos 60 10 80 Pardomuan Nauli 60 10 80 Pansurbatu 95 10 40 Pansurbatu 2 95 5 40 Hutatoruan VIII (Aek Nasia) 95 10 40 Aek Sian Simun 95 10 40 Hutatoruan III 95 10 40 Parbubu I 95 10 40 Hutatoruan I 95 10 50 Siraja Hutagalung 97 12 50 Simorangkir Julu 95 12 50 AHHs N/A 28.5 92 Source: Hearing with Acting Village Heads in July 2015

2) School Enrolment

In the two surveyed villages of Component 1, about 40% of the villagers finished primary school

followed by 20% who finished middle school (junior high school), and about 10% who finished high

school.

In the surveyed villages of Component 2, the average ratio of total villagers who finished primary school,

middle school, and high school is about 76%, ranging from 69% in Hutatoruan I Village to 89% in

Hutatoruan III Village. There is no gap on education level between female and male in all surveyed

villages. In each village, there is at least one established primary school.

Education level in the surveyed villages is shown in Table 7.2.11 and education infrastructure in the

surveyed villages is shown in Table 7.2.12.

Final Report

Preparatory Survey on North Sumatra Mini 7-13 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.11 School Enrolment Component 1: Hydropower Plants

Technical School/ College/

University (Female)

Finished High

School (Female)

Finished Middle School

(Female)

Finished Primary School

(Female)

No Schooling (Female)

No Schooling Yet (0-5

years old)

Total Female

Total Population

Siantar Naipospos Village

30 (18) 3%

120 (55) 11%

230(110)21%

420(200)39%

155(52)14%

128 (60) 12%

495 45.71%

1,083

Pardomuan NauliVillage

20 (10) 3%

70 (45) 10%

135(90)18%

317(150)43%

90(45)12%

100 (45) 14%

385 53%

732

AHHs 0 0 0 1 4 0 5 32Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Technical School/ College/

University (Female)

Finished High

School (Female)

Finished Middle School

(Female)

Finished Primary School

(Female)

No Schooling (Female)

No Schooling Yet (0-5

years old)

Total Female

Total Population

Siantar Naipospos Village

30 (18) 3%

120 (55) 11%

230(110)21%

420(200)39%

155(52)14%

128 (60) 12%

495 45.71%

1,083

Pardomuan NauliVillage

20 (10) 3%

70 (45) 10%

135(90)18%

317(150)43%

90(45)12%

100 (45) 14%

385 53%

732

Pansurbatu 14 (8)

1.47%

200 (125)

20.99%

287(154)

30.11%

342(85)

35.89%

50(23)

5.25%

60 (25)

6.29%

420 44.07%

953

Pansurbatu 2 2 (1)

0.62%

18 (9)

5.62%

55(19)

17.19%

150(53)

46.89%

50(20)

15.62%

45 (18)

14.06%

120 37.5%

320

Hutatoruan VIII (Aek Nasia)

9 (5)

1.85%

50 (28)

10.31%

102(57)

21.03%

220(130)

45.36%

61(20)

12.58%

43 (20)

8.87%

260 53.60

485

Aek Sian Simun

18 (10)

1.36%

220 (120)

16.61%

350(169)

26.43%

502(270)

37.91%

129(60)

9.75%

105 (46)

7.94%

675 50.98%

1,324

Hutatoruan III 15 (7)

2.88%

100 (40)

19.23%

165(95)

31.73%

200(60)

38.47%

30(14)

5.77%

10 (4)

1.92%

220 42.3%

520

Parbubu I 25 (15)

2.08%

201 (140)

16.75%

370(236)

30.83%

294(170)

24.5%

205(129)

17.09%

105 (60)

8.75%

750 62.5%

1,200

Hutatoruan I 124 (77) 7%

363 (187)

20.50%

401(219)

22.64%

452(207)

25.52%

242(120)

13.67%

189 (87)

10.67%

897 50.64%

1,771

Siraja Hutagalung

110 (70)

4.86%

400 (265)

17.66%

793(450)

35.01%

501(300)

22.12%

311(100)

13.73%

150 (60)

6.62%

1,245 54.97%

2,265

Simorangkir Julu

100 (65)

8.82%

210 (120)

18.53%

300(140)

26.48%

350(188)

30.90%

93(35)

8.21%

80 (55)

7.06%

603 53.22%

1,133

Source: Hearing with Acting Village Heads in July 2015

Final Report

Preparatory Survey on North Sumatra Mini 7-14 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.12 Education Infrastructure Component 1: Hydropower Plants

Village Primary School Middle School High School Technical

School/College/University

Vocational

Siantar Naipospos 2 1 0 0 0 Pardomuan Nauli 2 1 0 0 0 Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Primary School Middle School High School Technical

School/College/University

Other

Siantar Naipospos 2 1 0 0 0 Pardomuan Nauli 2 1 0 0 0 Pansurbatu 0 1 0 0 0 Pansurbatu 2 0 0 0 0 0 Hutatoruan VIII (Aek Nasia) 1 0 0 0 1 (pre-school)*Aek Sian Simun 2 0 0 0 0 Hutatoruan III 1 0 0 0 0 Parbubu I 2 0 0 0 0 Hutatoruan I 1 1 0 0 1 (pre-school)*Siraja Hutagalung 1 0 0 0 0 Simorangkir Julu 2 0 1 0 1 (pre-school)** Pre-school for children between 4 to 5 years old Source: Hearing with Acting Village Heads in July 2015

(5) Infrastructure

1) Health

There is one branch of health center (poskesdes) in each village of Component 1. In the poskesdes, one

midwife is deployed on a full time basis in each village of Component 1. Once a month, infant and baby

care service is provided at the poskesdes as part of the government program. The closest health center is

located in Kolang District (about 20 km from both villages) and the other in Adian Koting District (about

30 km from both villages). There is a hospital in Tarutung City (about 67 km from both villages) which

can provide advanced medical care; however, villagers prefer to go to the health center in Kolang or

hospital in Sibolga City (67 km from both villages) rather than in Adian Koting or Tarutung because of

better accessibility.

In the surveyed villages of Component 2, there are health facilities such as clinic, health center, or

representative of health center except in the villages of Pansurbatu and Pansurbatu 2. Baby care is

provided in all the surveyed villages except in the villages of Pansurbatu, Pansurbatu 1, and Siraja

Hutagalung.

Distance to health infrastructure from surveyed villages is shown in Table 7.2.13.

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Preparatory Survey on North Sumatra Mini 7-15 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.13 Health Infrastructure (Distance to Village) Component 1: Hydropower Plants

Village Hospital Clinic Health CenterVillage Nurse/

Doctor

Representative of Health Center (Pos

Kesehatan Desa/Poskesdes)

Baby Care (Pos Yandu/Pos

Pelayanan Tepadu)

Siantar Naipospos

67 km to a hospital in Tarutung 67 km to a hospital to Sibolga

- 32 km to Adian Koting 20 km to Kolang District

In the village (1 km from the project area) In the village (2 km from the project area)

In the village (2 km from the project area)

In the village (2 km from the project area)

Pardomuan Nauli

67 km to a hospital in Tarutung 67 km to a hospital to Sibolga

- 30 km to Adian Koting 21 km to Kolang District

In the village (2 km from the project area)

In the village (100 m from the project area)

In the village (100 m from the project area)

Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Hospital Clinic Health Center Village Nurse/ Doctor

Representative of Health Center (Pos

Kesehatan Desa/Poskesdes)

Baby Care (Pos Yandu/Pos

Pelayanan Tepadu)

Siantar Naipospos

67 km - 32 km to Adian Koting 20 km to Kolang District

1 km in Limus 2 km in Lobu Haminjon

In the village In the village

Pardomuan Nauli

67 km - 30 km to Adian Koting 21 km to Kolang District

2 km In the village In the village

Pansurbatu 57 km to Tarutung City

- 31 km to Adian Koting District

- - -

Pansurbatu 2 57.5 km to Tarutung City

- 31 km to Adian Koting District

- - In the village

Hutatoruan VIII (Aek Nasia)

8 km to Tarutung City

In the village (It is called “Poliklinik Desa” or village Polyclinic)

8km to Tarutung District - - In the village

Aek Sian Simun

2.5 km to Tarutung City

- 2 km to Tarutung District - In the village In the village

Hutatoruan III

2.2 km to Tarutung City

- 2 km to Tarutung District - In the village In the village

Parbubu I 3 km to Tarutung City

In the village (Poliklinik )

2 km to Tarutung District - - In the village

Hutatoruan I 3.5 km to Tarutung City

In the village (Poliklinik Desa)

1 km to Tarutung District - - In the village

Siraja Hutagalung

6 km to Tarutung City

- In the village (Puskesmas Pembantu)

- In the village -

Simorangkir Julu

4 km to Tarutung City

- In the village - In the village In the village

Source: Hearing with Acting Village Heads in July 2015

2) Road

The distance from the surveyed villages of Component 1 to the main road to the center of Adian Koting,

which is the administrative district of these villages located in the direction of Tarutung City, is about 41

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Preparatory Survey on North Sumatra Mini 7-16 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

km. Accessibility to the major road is very bad. In particular, the condition of the road along the 10 km

section between Bagot Nahrmop, a subvillage of Pardomuan Nauli Village, and Aek Nauli Village, where

the road is located along the proposed transmission lines from the villages of Component 1 to Tarutung

City, is unpaved and partly too narrow and steep to pass through even by motorbike. Consequently, it has

been inhabited by vehicles accessing to the villages from the Tarutung area.

In the surveyed villages of Component 2, the distance to the center of the district is far at about 30 km

from the villages of Pansurbatu, Pansurbatu 1, and Pansurbatu 2; however, most of the road is paved and

in good condition. Other villages are relatively close to the center of the district ranging from 0 km from

Simorangkir Julu Village to 8 km from Hutatoruan Village.

Accessibility from the surveyed villages to the main road is shown in Table 7.2.14.

Table 7.2.14 Access from the Village to the Main Road Component 1: Hydropower Plants Village Distance Condition Accessibility Siantar Naipospos 41 km Unpaved All year long Pardomuan Nauli 41 km Unpaved All year long Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines District Village Distance4 Condition Accessibility Adian Koting Siantar Naipospos 41 km Unpaved All year long

Pardomuan Nauli 41 km Unpaved All year long Pansurbatu 31 km - Paved : 26 km

- Unpaved: 5 km All year long

Pansurbatu 2 31 km - Paved : 26 km - Unpaved: 5 km

All year long

Tarutung Hutatoruan VIII (Aek Nasia) 8 km - Paved : 5 km - Unpaved: 3 km

All year long

Aek Sian Simun 2 km Unpaved All year long Hutatoruan III 2 km Unpaved All year long Parbubu I 2 km Unpaved All year long Hutatoruan I 1 km Unpaved All year long

Siatas Barita Siraja Hutagalung 2 km Unpaved All year long Simorangkir Julu 0 km Unpaved All year long

Source: Hearing with Acting Village Heads in July 2015

3) Electrification Rate

There is no grid connection in the two surveyed villages of Component 1. In the villages, electricity is

used mainly for lighting. Major source for lighting is from oil lamp followed by kerosene oil generator.

Cost of oil varies depending on the duration of lighting usage. Some households share the cost of oil

generator with 2 to 15 households depending on the size of the generator.

Except in Siantar Naipospos Village and Pardomuan Nauli Village, all the surveyed villages in

Component 2 are connected to the grid ranging from 96% in Panturubatu 1 Village to 100% for the

remaining eight villages. Electrification rate in the surveyed villages is shown in Table 7.2.15.

4 Distance from each village to respective district office, i.e.: Adian Koting District, Tarutung District, or Siatas Barita District.

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Preparatory Survey on North Sumatra Mini 7-17 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.15 Electrification Rate Component 1: Hydropower Plants Village Connected to

the Grid (%) Battery (%) Oil Lamp Only

(%) Oil Generator (%)

Waterwheel (%)

Cost of Oil/Month

Siantar Naipospos 0 0 60 39.9 0.1 Rp540,000 (2 liters x Rp9,000)

Pardomuan Nauli 0 0 70 30 0 Rp540,000 (2 liters x Rp9,000)

Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines Village Connected to

the Grid (%) Battery (%) Oil Lamp Only

(%) Oil Generator (%)

Waterwheel (%)

Cost of Oil/Month

Siantar Naipospos 0 0 60 39.9 0.1 Rp540,000 (2 liters x Rp9,000)

Pardomuan Nauli 0 0 70 30 0 Rp540,000 (2 liters x Rp9,000)

Pansurbatu 100 0 0 0 0 0Pansurbatu 2 100 0 0 0 0 0Hutatoruan VIII (Aek Nasia)

100 0 0 0 0 0

Aek Sian Simun 100 0 0 0 0 0Hutatoruan III 100 0 0 0 0 0Parbubu I 100 0 0 0 0 0Hutatoruan I 100 0 0 0 0 0Siraja Hutagalung 100 0 0 0 0 0Simorangkir Julu 100 0 0 0 0 0Source: Hearing with Acting Village Heads in July 2015

4) Water Supply

Major source of water is from spring and few households use rain water in the two surveyed villages of

Component 1. The spring water taken from the mountains is available at the public space or directly

connected to the private compound via plastic hose. In Siantar Naipospos Villlage, there are nine public

water supply spaces including toilet. In Pardomuan Nauli Village, there are also nine public water supply

spaces including toilet. The water is used for cooking, bathing, drinking, and washing on a daily basis.

In 5 out of the 12 surveyed villages of Component 2, the source of water is spring water ranging from

97% in Siantar Naipospos to 100% in the villages of Pansurbatu, Pansurbatu 1, and Pansurbatu 2. On the

other hand, tap water is connected to the rest of the six villages ranging from 60% in Hutatoruan VIII to

100% in the villages of Hutatoruam III and Simorangkir Julu.

Source of water in the surveyed villages is shown in Table 7.2.16. The public water supply space is

shown in Figure 7.2.4.

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Preparatory Survey on North Sumatra Mini 7-18 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.16 Source of Water Component 1: Hydropower Plants Village Tap Water (%) Well (%) Spring (%) River/Stream (%) Rain (%) Siantar Naipospos 0 0 97 0 3Pardomuan Nauli 0 0 98 0 2Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines Village Tap Water (%) Well (%) Spring (%) River/Stream (%) Rain (%) Siantar Naipospos 0 0 97 0 3Pardomuan Nauli 0 0 98 0 2Pansurbatu 0 0 100 0 0Pansurbatu 2 0 0 100 0 0Hutatoruan VIII (Aek Nasia) 60 0 38 2 0Aek Sian Simun 80 20 0 0 0Hutatoruan III 100 0 0 0 0Parbubu I 70 30 0 0 0Hutatoruan I 90 10 0 0 0Siraja Hutagalung 90 10 0 0 0Simorangkir Julu 100 0 0 0 0Source: Hearing with Acting Village Heads in July 2015

Source: USU

Figure 7.2.4 Public Water Supply Space

5) Source of Cooking Energy

In the two surveyed villages of Component 1, wood is the main source of energy for cooking. Villagers

collect wood from the surrounding area of their plantation to help save cost of buying firewood.

In the surveyed villages of Component 2, wood is the main source of energy for cooking in the

mountainous villages such as Siantar Naipospos, Pardomuan Nauli, Pansurbatu, Pansurbatu 1, and

Pansurbatu 2. On the other hand, gas and electricity are the main sources of energy for cooking in the

villages of Aek Sian Simun, Hutatoruan III, Parububu 1, Hutatoruan I, Siraja Hutagalung, and

Simorangkir Julu.

Sources of energy for cooking in the surveyed villages are shown in Table 7.2.17.

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Preparatory Survey on North Sumatra Mini 7-19 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.17 Sources of Energy for Cooking Component 1: Hydropower Plants

Village Wood (%)Charcoal

(%) Gas (%)

Electricity (%)

Kerosene Stove (%)

Wood and Kerosene Stove (%)

Wood, Gas and Kerosene Stove (%)

Siantar Naipospos 94.5 0 0 0 4 1 0.5Pardomuan Nauli 94 0 0 0 5 1 0Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Wood (%)Charcoal

(%) Gas (%)

Electricity (%)

Kerosene Stove (%)

Wood and Kerosene Stove (%)

Wood, Gas and Kerosene Stove (%)

Siantar Naipospos 94.5 0 0 0 4 1 0.5Pardomuan Nauli 94 0 0 0 5 1 0Pansurbatu 50 0 5 10 25 5 5Pansurbatu 2 50 0 5 10 30 5 0Hutatoruan VIII (Aek Nasia)

35 0 5 10 35 15 0

Aek Sian Simun 0 0 55 40 5 0 0Hutatoruan III 0 0 55 44 1 0 0Parbubu I 0 0 50 30 10 10 0Hutatoruan I 0 0 50 30 20 0 0Siraja Hutagalung 0 0 55 40 5 0 0Simorangkir Julu 0 0 50 45 5 0 0Source: Hearing with Acting Village Heads in July 2015

6) Transportation

In the two surveyed villages of Component 1, motorbike is the main means of transport followed by

bicycle. There is a motorbike rental service between the two villages and Kolang District (20 km from the

two villages). The travel cost of one round trip is Rp100,000. There is no service to the direction of Adian

Koting District (40 km from the two villages) and Tarutung City (67 km from the two villages) due to bad

road condition. The high cost of transportation, far distance to the center of the districts, or bad road

condition confine the mobility of goods and villagers. Moreover, the lack of transport vehicles in the

villages has been an obstacle in transporting agricultural produce from the villages to the big markets

outside of the villages, thus, limiting business opportunities.

In all the surveyed villages of Component 2, motorbike is the main means of transport as well.

Means of transportation in the surveyed villages are shown in Table 7.2.18.

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Preparatory Survey on North Sumatra Mini 7-20 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.18 Means of Transportation Component 1: Hydropower Plants

Village Mini-Bus Private Car Motorbike Bicycle Siantar Naipospos 0 1 50-65 20Pardomuan Nauli 0 0 40-50 10Source: Hearing with Acting Village Heads in April 2015

Component 2: Transmission Lines

Village Mini-Bus Private Car Motorbike Bicycle Siantar Naipospos 0 1 50-65 20Pardomuan Nauli 0 0 40-50 10Pansurbatu 1 0 90-115 5-8Pansurbatu 2 1 0 40-42 2-3Hutatoruan VIII (Aek Nasia) 1 1 70-82 1-2Aek Sian Simun 2 1 230-245 1-3Hutatoruan III 1 1-2 50-55 1-2Parbubu I 2 1-2 200-210 4-6Hutatoruan I 2 1-3 300-320 1-4Siraja Hutagalung 5 1-5 450-490 1-5Simorangkir Julu 5 1-5 200-220 1-4Source: Hearing with Acting Village Heads in July 2015

(6) Public Health

1) Medical Treatment

In the two surveyed villages of Component 1, 60% of the villagers prefer to be given medical treatment at

home followed by treatment at a branch of health center or at the house of a licensed midwife/nurse in the

villages (40%).

In the surveyed villages of Component 2, the ratio of villagers who prefer to be given medical treatment

at home is quite high ranging from 35% in Siraja Hutagalung Village to 60% in Pardomuan Nauli

Village.

Places for medical treatment in the surveyed villages are shown in Table 7.2.19.

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Preparatory Survey on North Sumatra Mini 7-21 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.19 Places for Medical Treatment Component 1: Hydropower Plants

Village Treat at Home (%)

Village Health Center (%) Clinic(%)

Hospital(%)

Village Nurses (Bidan/Mantri)/ Representatives of Health Center in

Village (Pos Kesehatan Dosa/Poskesdes) (%)

Traditional Healer

(Datu) (%)

Siantar Naipospos 59 0 0 0 40 1Pardomuan Nauli Village

60 0 0 0 39 1

Source: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Village Treat at Home (%)

Village Health Center (%) Clinic(%)

Hospital(%)

Village Nurses (Bidan/Mantri)/Representatives of

Health Center in Village (Pos Kesehatan Dosa/Poskesdes) (%)

Traditional Healer

(Datu) (%)

Siantar Naipospos 59 0 0 0 40 1Pardomuan Nauli 60 0 0 0 39 1Pansurbatu 50 50 (go to “Puskesmas

Pembantu” in Pansurbatu 1 Village)

0 0 0 0

Pansurbatu 2 55 45 (go to “Puskesmas Pembantu” in Pansurbatu 1 Village)

0 0 0 0

Hutatoruan VIII (Aek Nasia)

45 35 (go to “Puskesmas Pembantu” in Pansurbatu 1 Village)

20 0 0 0

Aek Sian Simun 40 0 0 0 60 0Hutatoruan III 40 0 0 0 60 0Parbubu I 45 0 30 0 25 (go to “Poskesdes” in Aek Sian

Simun Village) 0

Hutatoruan I 50 0 50 0 0 0Siraja Hutagalung 35 35 0 0 30 0Simorangkir Julu 40 30 0 0 30 0Source: Hearing with Acting Village Heads in July 2015

2) Health Issues in the Community

In all the surveyed villages, the dominant health issues in the past 12 months are fever and influenza

followed by cough and gastritis. Number of cases and death within 12 months in the surveyed villages is

shown in Table 7.2.20.

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Preparatory Survey on North Sumatra Mini 7-22 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.2.20 Number of Cases and Deaths within 12 Months Component 1: Hydropower Plants

Vil

lage

Mal

aria

Den

gue

Dia

rrhe

a

Infa

nt

Mor

tali

ty

HIV

/AID

S

Hea

rt

Att

ack

Lun

g D

isea

ses

Hig

h B

lood

P

ress

ure

Fev

er a

nd

Infl

uenz

a

Rin

gwor

m

Tin

ea

Ver

sico

lor

Scab

ies

Cou

gh

Gas

trit

is

C D C D C D C D C D C D C D C D C D C D C D C D C D C DSN 0 0 0 0 5 0 0 0 0 0 7 0 1 0 1 0 30 0 2 0 1 0 1 0 21 0 20 0PN 0 0 0 0 3 0 1 0 1 0 1 0 3 0 4 0 20 0 2 0 2 0 1 0 25 0 13 0SN:Siantar Naipospos Village, PN:Pardomuan Nauli Village, C:Cases, D:DeathsSource: Hearing with Acting Village Heads in April 2015 Component 2: Transmission Lines

Vil

lage

Mal

aria

Den

gue

Dia

rrhe

a

Infa

nt M

orta

lity

HIV

/AID

S

Hea

rt A

ttac

k

Lun

g D

isea

ses

Hig

h B

lood

P

ress

ure

Fev

er a

nd

Infl

uenz

a

Rin

gwor

m

Tin

ea V

ersi

colo

r

Sca

bies

Cou

gh

Gas

trit

is

Eld

erly

Dis

ease

(a

dis

ease

of

old

age)

Cer

ebro

vasc

ular

A

ccid

ent (

CV

A)

Dia

bete

s

Kid

ney

Dis

ease

s

C D C D C D C D C D C D C D C D C D C D C D C D C D C D C D C D C D C DSN 0 0 0 0 5 0 0 0 0 0 7 0 1 0 1 0 30 0 2 0 1 0 1 0 21 0 6 0 0 0 0 0 0 0 0 0PN 0 0 0 0 3 0 1 0 1 0 1 0 3 0 4 0 20 0 2 0 2 0 1 0 25 0 13 0 0 0 0 0 0 0 0 0PB 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 21 0 0 0 0 0 0 0 15 0 0 0 5 3 0 0 0 0 0 0PB2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 0 0 0 0 0 0 0 20 0 0 0 0 0 3 3 10 7 0 0HT VIII 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 25 0 0 0 0 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0ASS 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 0 0 0 0 0 0 0 12 0 0 0 0 0 0 0 0 0 0 0HT III 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 27 0 0 0 0 0 0 0 22 0 5 0 0 0 0 0 0 0 0 0PRB I 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 30 0 0 0 0 0 0 0 35 0 12 0 0 0 0 0 0 0 0 0HT I 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 20 0 0 0 0 0 0 0 20 0 5 0 0 0 0 0 0 0 0 0SHG 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 45 0 0 0 0 0 0 0 25 0 22 0 2 0 0 0 0 0 1 1SMJ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 50 0 0 0 0 0 0 0 30 0 30 0 2 0 0 0 0 0 0 0SN:Siantar Nipospos Village, PN: Pardomuan Nauli Village, PB:Pansurbatu Village, PB2:Pansurbatu 2 Village, HT VIII: Hutatoruan VIII (Aek Nasia) Village, ASS: Aek Sian Simun Village, HT III: Hutatoruan III Village, PRB I: Parbubu I Village, HT I: Hutatoruan I Village, SHG: Siraja Hutagalung Village, SMJ: Simorangkir Julu Village, C:Cases, D:Deaths Source: Hearing with Acting Village Heads in July 2015

7.3 LEGAL AND INSTITUTIONAL FRAMEWORK

7.3.1 LEGISLATION ON NATURAL AND SOCIAL ENVIRONMENTAL CONSIDERATIONS

(1) Legislations Regarding Environmental Assessment

The statutory order in Indonesia is summarized in Table 7.3.1.

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Preparatory Survey on North Sumatra Mini 7-23 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.3.1 Summary of Statutory Order in Indonesia Priority Jurisdiction Category Translation in English

1 National Undang Undang Dasar (UUD) Constitution 2 Undang Undang (UU) Law 3 Peraturan Pemerintah (PP) Government Regulation 4 Peraturan Menteri (PERMEN)

PERMEN LH Ministerial Regulation Environmental Ministerial Regulation

5 Keputusan Menteri (KEPMEN) KEPMEN LH MENHUT-ll

Ministerial Decree Environmental Ministerial Decree Ministry of Forestry Decree

6 Keputusan Kepala Bappedal Decree of Head of Environment Impact Control Board 7 Regional Peraturan Daerah Provincial Government Regulation 8 Keputusan Guberner Decree of Governor - - Surat Edaran Circular Source: JICA Survey Team

Environmental assessment is carried out based on the Environmental Protection and Management Law

(2009) which defines the principle, purpose, and scope of environmental management. The regulation

entitled “Type of Business and Activities that Need to Prepare Environmental Impact Assessment Report

(AMDAL)”, which was enacted in 2012, presents the definitions of the projects that need to conduct

environmental impact assessment (EIA) for preparing an AMDAL and the projects that need to conduct

initial environmental examination (IEE) for preparing the environmental management and monitoring

plan (UKL-UPL). In order to obtain an environmental permit from the environmental authority, the

project owner needs to prepare AMDAL or UKL-UPL depending on the project definition and submit it

to the environmental authority such as the Ministry of Environment or Department of Environment in the

local government based on the scale of the project.

Procedure and format of UKL-UPL are stipulated in the Guideline to Develop Environmental Document

(2012). The list of main legislations regarding the project’s environmental assessment is shown in Table

7.3.2.

Table 7.3.2 Key Legislations Regarding Environmental Impact Assessment

No. Category Title Enacted Year Code

1

Environmental Assessment

Environment Protection and Management Law 2009 UU No.32

2 Law on Environmental Management 2010 Surat Edaran No.B-5362/Dep.l-l/LH

3 Environmental Management Plan and Environmental Monitoring Plan 2010 PERMEN THN No.13

4 Requirement of Consultant for Registration 2010 PERMEN LH No.7

5 Types of Business and Activities That Need to Prepare AMDAL 2012 PERMEN LH No.5

6 Guidelines to Develop Environmental Documents 2012 PERMEN LH No.16

7 Guidelines for Community Involvement 2012 PERMEN LH No.17

8 Environmental Permit 2012 PERMEN LH No.27

9 Regulation on Water Resources Management 2008 PP No.42

10 Environmental Standards on Air Quality 1999 PP No.41

11 Air Pollution Standard Index 1997 KEPMEN LH No.45

12 Environmental Standards on Water Quality 2001 PP No.82

13 Environmental Standards on Noise 1996 PERMEN LH No.48

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14 Environmental Standards on Vibration 1996 PERMEN LH No.49

15 Environmental Standards on Odor Level 1996 KEPMEN No.50

16 Natural Environment

Regulation on River 2011 PP No.38

17 Law on Water Resources 2004 UU No.7

18 Law on the Conservation of Natural Biological Resources and Its Ecosystem 1990 UU No.5

19 Conservation of Flora and Fauna 1999 PP No.7

20 Law on Forestry 1999 UU No.41

21 Cultural Heritages

Law on Cultural Heritages 1992 UU No.5

22 Procedures at the Time of Historical/Cultural Discovery during Construction Phase 1993 PP No.10

Source: JICA Survey Team

(2) Environmental Assessment Procedures for the Project

The project is required to obtain an environmental permit, which is one of the required materials to

acquire a construction permit (IMB).

The process to obtain the environmental permit is as follows: According to the Regulation No. 5 (Types

of Business and Activities That Need to Prepare Environmental Impact Assessment Report) (Perman LH

05 Tahun, 2012), the project does not apply to the conditions stipulated in K3.1.C (transmission line

construction of more than 150 kV) or K.3.2.C (dam height of more than 15 m, reservoir size of more than

200 ha, and electricity generation capacity of more than 50 MW). Accordingly, the project is not required

to develop AMDAL but will only prepare UKL-UPL. The prepared UKL-UPL shall be submitted to the

environmental department in North Tapanuli District in order to obtain a recommendation letter. Together

with the recommendation letter, the project owner shall submit UKL-UPL to the District Head in North

Tapanuli District to obtain an environmental permit. The required content of UKL-UPL is stipulated in

Regulation No.16 (Guidelines to Develop Environmental Documents) (2012). It is considered that the

requirement of preparing UKL-UPL is much similar to that of the initial environmental examination

(IEE). The summary of the contents of UKL-UPL is shown in Table 7.3.3.

Table 7.3.3 Contents of UKL-UPL Chapter Required Contents of UKL-UPL A.

1. 2.

Project Owner’s Profile (Project’s) Owner’s name Address, phone number, fax, email

B 1. 2. 3. 4.

Project Plan and Activity Project name Location of the project/activity Scale of the project/activity Outline of the project/activity in each phase (pre-construction/construction/operation)

C. 1. 2. 3. 4.

Environmental Impact Assessment, its Mitigation Plan and Environmental Monitoring Plan Environmental Impact Environmental Mitigation Plan Environmental Monitoring Plan Institutional Arrangement for the Monitoring Plan

D. Necessary Permission to Obtain (in case of PPLH) E. Statement on the Commitment of Carrying Out the UKL-UPL by the Project Owner F. Bibliography of the UKL-UPL G. Appendices

Source: Guideline to Develop Environmental Document, PERMEN LH No.16 2012

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Preparatory Survey on North Sumatra Mini 7-25 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

The state of environmental procedure and further requirements on environmental permit in each project’s

component are summarized in Table 7.3.4. As for the small hydropower plants and related facilities of

Poring-1 and Poring-2, UKL-UPL have been certified and environmental permit have been obtained since

April 2013. The certified UKL-UPL will expire after three years from the certification date in case of no

commencement of construction activity before the expiry date. As for the transmission lines of Poring-1

and Poring-2, the UKL-UPL shall be developed and environmental permit shall be obtained.

Table 7.3.4 State of Environmental Procedure and Further Requirements Component Present State Further Requirements

UKL-UPL Environmental Permit

Poring-1 Mini Hydropower Plant and its Related Facilities

Certified on 10 April 2013

Issued on 16 April 2013

Poring-1 Mini Hydropower Plant and its Related Facilities

Poring-2 Mini Hydropower Plants and its Related Facilities

Certified on 10 April 2013

Issued on 16 April 2013

Poring-2 Mini Hydropower Plants and its Related Facilities

Transmission Line for Poring-1 Mini Hydropower Plant

Submitted in September and it has been under review

Not obtained Transmission line for Poring-1 Mini Hydropower Plant

Transmission Line for Poring-2 Mini Hydropower Plant

Submitted in September 2015 and it has been under review

Not obtained Transmission line for Poring-2 Mini Hydropower Plant

Source: JICA Study Team

(3) Land Acquisition Procedure

As for the private investment project, the project owner shall obtain location permit (Izim Lokasi) from

North Tapanuli District government. With the permit, the project owner starts acquiring land for the

project. In the case of this project, the project area consists of two types of land, i.e., forest land and

agricultural land. The land acquisition procedure in each land category is as follows:

1) Forest Land

The whole area of Component 1 and a part of Component 2 are located in the production forest under the

management of the Ministry of Forestry. Accordingly, it needs to obtain permission from the Ministry of

Forestry due to conversion of land category from forest land to private land to be used for investment.

Project owner shall make a request for land conversion to the Department of Forestry in North Tapanuli

District government. After endorsement by the Department of Forestry in North Tapanuli District

government, the request will be processed to the Ministry of Forestry with the recommendation letter

issued by the Governor of North Sumatra. Then, the permission is obtained after the Ministry of Forestry

approved the request.

2) Agricultural Land

There is no legal procedure on land acquisition for the case of private investment project. The content of

sales contract, compensation method, and any other land affairs for the affected land shall be developed

based on the agreement between the project owner and affected households.

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Preparatory Survey on North Sumatra Mini 7-26 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(4) Environmental and Social Considerations by JICA

The project is required to comply with the JICA Guidelines for Environmental and Social Considerations

(the Guidelines). Based on the Guidelines, the project was classified as a Category B project. It is

stipulated that “generally, the proposed projects are site-specific, few if any are irreversible; and in most

cases, normal mitigation measures can be designed more readily”5 . As for Category B project,

environmental and social consideration studies require the IEE level, including mitigation measures to

avoid, minimize, or compensate for adverse impact, monitoring plan, and institutional arrangement. It

also needs to analyze alternatives covering the “without project” situations. Consultations with local

stakeholders on the result of the environmental and social considerations shall be conducted for all

Category A projects and for Category B projects as needed.

7.3.2 INSTITUTIONAL FRAMEWORK

The North Tapanuli District government is the key governmental administrative body in relation to the

project’s environmental and social consideration. The governmental administrative bodies relevant to the

study are shown in Table 7.3.5.

Table 7.3.5 Governmental Administrative Bodies Relevant to the Project Institution Role

Natural Environment Dept. of the North Tapanuli District Government

Reviews the submitted UKL-UPL and issues recommendation letter after approval of the UKL-UPL

Head/Vice Head of the North Tapanuli District Government

Issues environmental permit after receipt of the recommendation letter from the Natural Environmental Office of the North Tapanuli District government

Natural Environment Dept. of the North Sumatra Province Government

Gives advice to the Natural Environment Department of the North Tapanuli District government, as necessary

Dept. of Mining and Energy of the North Tapanuli District Government

Reviews the submitted UKL-UPL and gives comments to the Natural Environment Department of the North Tapanuli District government during review period of the UKL-UPL

Dept. of Integrated Permitted Service of the North Tapanuli District Government

Reviews the submitted UKL-UPL and gives comments to the Natural Environment Department of North Tapanuli District government during review period of the UKL-UPL

Dept. of Land Affairs of the North Tapanuli District Government

Reviews the submitted UKL-UPL and gives comments to the Natural Environment Department of the North Tapanuli District government during review period of the UKL-UPL

Dept. of Forestry of the North Tapanuli District Government

Reviews the application of request for forest conversion and issues recommendation letter (approval letter) to the Governor of North Sumatra Province

Governor of North Sumatra Province

Issues recommendation letter to the Ministry of Forestry for obtaining permission of forest conversion

Ministry of Forestry Reviews the application of forest conversion request and issues permit of the conversion Reviews the application of IPPKH (permit of land development) submitted by the project owner (private investment) and issues the IPPKH

Source: JICA Survey Team

5 2.2 Categorization, JICA Guidelines for Environmental and Social Considerations, 2010

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Preparatory Survey on North Sumatra Mini 7-27 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

7.4 ALTERNATIVES

(1) Poring-1 Mini Hydropower Plant

Two alternatives were considered for the location of intake weir. For both alternatives, no impact is

anticipated on the upstream cultivation area due to the rise of the water level as a result of constructing

the intake weir. As for the required land area, almost the same area needs to be acquired for the two

alternatives. Even the conditions of the two alternatives are almost the same, Alternative 2 is selected.

Because Alternative 2 contributes in the increase in access to the Poring River through the construction of

access road, which is to be used not only by the construction vehicles but also by the villagers. Opening

the new access road to the Poring River gives an opportunity for creating a new fishing site and

compensates the decrease of fishing opportunity due to diversion of water from the Poring River to the

headrace channel of Poring-1 after constructing the Poring-1 Intake Weir. The comparison table of

alternatives is shown in Table 7.4.1.

Table 7.4.1 Alternatives

Alternatives Impact to Upstream

Cultivation Area Land Acquisition Evaluation

Alternative 1 No impact: no cultivation area to be impacted due to the water level rise

Length of headrace channel: 2.91 km No need to construct access road

Alternative 2 is selected Reason: Although almost the same area needs to be acquired for Alternative 1 and Alternative 2, Alternative 2 contributes in the increase in access for the villagers to the Poring River through the construction of the access road.

Alternative 2 No impact: no cultivation area to be impacted due to the water level rise

Length of headrace channel: 2.5 km About 0.45 km of access road to the intake needs to be constructed

Source: JICA Survey Team

(2) Poring-2 Mini Hydropower Plant

After confirming that the headrace channel of Poring-2 would affect the public graveyard, primary school,

and church, an alternative location for the headrace channel was considered to avoid these public facilities.

Consequently, the headrace channel was moved about 20 m toward the mountain side from the original

plan in order to avoid any effects on these facilities from land acquisition due to the construction of the

headrace channel. The original plan and alternative plan are shown in Figure 7.4.1.

Source: JICA Survey Team

Figure 7.4.1 Original Layout and Alternative Layout for Headrace Channel

Headrace Chanel

Public Road

Public Road (read line) Headrace Chanel (blue line)

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Preparatory Survey on North Sumatra Mini 7-28 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(3) Transmission Lines of the Poring-1 Mini Hydropower Plant and Poring-2 Mini Hydropower Plant

Two alternative transmission line routes were considered. Alternative 1 was aligned along the existing

public road from the Tarutung Substation to the Poring-1 Mini Hydropower Plant. Alternative 2 was

aligned avoiding existing public road and traverses mainly agricultural land from the Tarutung Substation

up to the point in Aek Nauli Village, where there is no distribution line pole constructed along the road.

The rest of the 14 km line route was aligned along the existing public road from the point in Aek Nauli

Village until the Poring-1 Mini Hydropower Plant. The length of the transmission line of Alternative 1 is

shorter than that of Alternative 2. However, in the case of Alternative 1, there are many structures such as

distribution line poles or shops already constructed along the road and it is difficult not to affect these

structures in many areas. Alternative 2 also affects the agricultural land. However, Alternative 2 was

selected because it will not affect structures; thus, no resettlement will occur.

7.5 SCOPING

Based on the findings from the field reconnaissance, hearings with the authorities concerned as well as

collected information from relevant institutions, the positive/negative impacts resulting from the project

in the construction phase and operation phase were estimated. In the course of the scoping process, the

UKL-UPLs6 of the Component 1 (Mini Hydropower Plants) were reviewed and reflected on the scoping.

The scoping on the Component 1 (Mini Hydropower Plants) and the Component 2 (Transmission Lines)

are shown in Table 7.5.1 and Table 7.5.2, respectively.

Table 7.5.1 Anticipated Impact on Component 1 (Hydropower Plants)

No. Impacts Rating

Brief Description Pre-/Const

ruction Operation

1. Anti-Pollution 1.1 Air Pollution C - Construction: Air pollution such as exhaust fumes from earthmoving equipment as

well as construction vehicle associated with the facilities of hydropower plant construction is anticipated Operation: No activity that will cause air pollution is anticipated.

1.2 Water Pollution B U Construction: Temporary water pollution due to concrete mixing, aggregate collection and excavation is anticipated. In addition, temporary water pollution from contractor’s/employee’s camp/office is anticipated. Operation: Anticipated impact is unknown at this stage after diverting the river water to headrace channels. Water quality analysis needs to be conducted to assess the impact on the water quality.

1.3 Waste B - Construction: Construction waste soil will be generated mainly from the powerhouse construction site. Vegetable debris will be generated at the time of land clearance for the land of powerhouse, headrace channel, intake weir, and access road. Also, waste such as kitchen scraps and human waste will be generated from worker’s camps and construction office. Operation: No activity that will cause waste is anticipated.

1.4 Soil Contamination - - Construction: No soil contamination is predicted. Operation: No soil contamination is predicted.

6 UKL-UPL (environmental management and monitoring plan) for the Poring-1 Mini Hydropower Plant and Poring-2 Mini

Hydropower Plant were already prepared by the project owner (JDG Poring for the Poring-1 Mini Hydropower Plant and JDG

Cianten for the Poring-2 Mini Hydropower Plant) and certified by the North Sumatra District Government in 2013.

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Preparatory Survey on North Sumatra Mini 7-29 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

No. Impacts Rating

Brief Description Pre-/Const

ruction Operation

1.5 Noise and Vibration

C C Construction: Noise and vibration resulting from construction activities are anticipated. Operation: Noise from the powerhouse will affect residents along the powerhouse area.

1.6 Ground Subsidence

- - Construction/Operation: No activity that will cause ground subsidence is anticipated.

1.7 Offensive Odor - - Construction/Operation: No activity that will cause offensive odor is anticipated. 1.8 Bottom Sediment - - Construction/Operation: No activity that will affect bottom sediment is anticipated.2. Natural Environment 2.1 Protected Area - - Construction/Operation: The project area is not located in a protected area. 2.2 Flora, Fauna, and

Biodiversity U U Construction/Operation: Some impacts on existing habitats will be anticipated due

to changing land use patterns. It is necessary to confirm with relevant administrative body if the habitat of endangered species is located within the project area.

2.3 Hydrological Situation

- U Construction: No activity that will affect hydrological situation is anticipated. Operation: Change in the hydrological situation of the section where the water from the Poring River is diverted to the headrace channel is expected. Maintenance flow for this section shall be estimated.

2.4 Topography and Geographical Features

B - Construction: Topography and geographical features will be affected due to constructing powerhouse, headrace channel, intake weir, and access road Operation: No activity that will affect topography and geographical features is anticipated.

3. Social Environment 3.1 Involuntary

Resettlement B - Construction: No resettlement is needed since the location of all facilities avoided

the residential area. However, due to constructing the facilities and access road, about 40 ha of land will be acquired. Operation: No activity that will cause involuntary resettlement is anticipated.

3.2 Vulnerable (poor households, female- headed households)

U - Construction: Vulnerability on affected people needs to be confirmed in conducting hearings with relevant administrative bodies and affected people. Operation: No activity that will affect the vulnerable group is anticipated.

3.3 Indigenous and Ethnic Minority

C - Construction: Villagers in the project area belong to the Toba Batak ethnic group. Low rate of understanding of Indonesian language by the villagers will affect communication between villagers and project owner/contractor. Operation: No activity that will affect indigenous and ethnic minority is anticipated.

3.4 Local Economy, Employment, and Livelihood

B+ B+ Construction: Positive impact such as creation of local employment is predicted. Operation: Positive impact such as creation of local employment is predicted.

3.5 Land Use and Utilization of Local Resources

C - Construction: Due to the project, 40 ha of land will be converted from plantation/agricultural land. Operation: No activity that will impact on land use or change of local resources is predicted.

3.6 Water Usage or Water Rights of Common

U U Construction/Operation: User of the Poring River among locals in the project area need to be surveyed for estimating the impact from the project.

3.7 Existing Social Infrastructures and Services

A+ - Construction: In order to improve accessibility of construction vehicles to the project area, the main road from Tarutung to the villages will be upgraded. It will help the accessibility of the villagers to Tarutung area. Operation: No activity that will affect existing social infrastructures and services is anticipated.

3.8 Social Institutions and Local Decision-making

- - Construction/Operation: No activity that will affect social institutions and local decision-making is anticipated.

3.9 Misdistribution of Benefit and Damage

- - Construction/Operation: No activity that will cause misdistribution of benefit and damage is anticipated.

3.10 Local Conflict of Interest

- - Construction/Operation: No activity that will cause local conflict of interest is anticipated.

3.11 Cultural Heritage - - Construction/Operation: No cultural heritage is confirmed within the project 3.12 Landscape C - Construction: Construction of the facilities such as powerhouse and intake weir will

change the scenery. Operation: No activity that will affect landscape is anticipated.

3.13 Gender C - Construction: Unfair involvement due to gender bias in the process of land acquisition will cause unfair distribution of compensation.

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Preparatory Survey on North Sumatra Mini 7-30 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

No. Impacts Rating

Brief Description Pre-/Const

ruction Operation

Operation: No activity that will cause gender issues is anticipated. 3.14 Children’s Rights - - Construction/Operation: No activity that will affect children’s rights is anticipated.3.15 Communicable

Diseases such as HIV/AIDS

C - Construction: Inflow of construction workers from construction worker’s camp to local communities will raise risks of communicable diseases. Operation: No activities raising the risk of communicable diseases in the local communities are anticipated.

3.16 Working Environment (includes work safety)

B - Construction: Inappropriate management of working environment will raise the risk of accident and decease. Operation: No activities raising the risk of working environment is anticipated.

4. Others 4.1 Accidents C - Construction: The effect of construction vehicles to the local community is

anticipated. Operation: No activities that will cause accidents are anticipated.

4.2 Global Warming - B+ Construction: CO2 emission from construction vehicles is not significant. Operation: Since the hydropower plant uses renewable energy, it will contribute to reduce CO2 emission.

Rating: A: Serious impact is anticipated, B: Some impact is anticipated, C: Small impact is anticipated, +Positive impact is anticipated, U: Extent of impact is unknown and examination is needed, Impact may become clear as study progresses, -: No impact is anticipated Source: JICA Survey Team

Table 7.5.2 Anticipated Impact on Component 2 (Transmission Lines)

-No. Impacts Rating

Brief Description of Result Pre-/Const ruction

Operation

1. Anti-Pollution 1.1 Air Pollution C - Construction: Air pollution such as exhaust fumes from earthmoving equipment as

well as construction vehicle associated with the tower construction is anticipated. Operation: No activity that will cause air pollution is anticipated.

1.2 Water Pollution B - Construction: Temporary water pollution due to concrete mixing at substation and excavation for digging hole to bury transmission pole is anticipated. In addition, temporary water pollution from contractor’s/employee’s camp/office is anticipated. Operation: No activity that will cause water pollution is anticipated.

1.3 Waste C - Construction: Soil will be excavated for burying construction pole and installing transformer at substation; however, the soil will be backfilled and no waste soil will be generated. Waste such as kitchen scraps and human waste will be generated from the worker’s camps and construction office. Operation: No activity that will cause waste is anticipated.

1.4 Soil Contamination - C Construction: No soil contamination is predicted. Operation: Inappropriate management of transformer will cause oil leakage. Consequently, it will contaminate the soil.

1.5 Noise and Vibration

C - Construction: Noise and vibration resulting from construction activities are anticipated. The main cause of noise and vibration are generated at the time of digging hole for burying transmission pole. Operation: No activity that will cause noise and vibration.

1.6 Ground Subsidence

- - Construction/Operation: No activity that will cause ground subsidence is anticipated.

1.7 Offensive Odor - - Construction/Operation: No activity that will cause offensive odor is anticipated. 1.8 Bottom Sediment - - Construction/Operation: No activity that will affect bottom sediment is anticipated.2. Natural Environment 2.1 Protected Area - - Construction/Operation: The project area is not located in a protected area. 2.2 Flora, Fauna, and

Biodiversity U - Construction: Mammal survey and bird survey along the transmission line route as

well as hearing with relevant administrative body will be conducted in order to grasp the present condition of the natural environment and assess the impact from the project. Operation: No activity that will cause negative impact on flora, fauna and biodiversity is anticipated.

2.3 Hydrological Situation

- - Construction/Operation: No activity that will cause negative impact on hydrological situation is anticipated.

2.4 Topography and C - Construction: Topography and geographical features will be affected due to the

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Preparatory Survey on North Sumatra Mini 7-31 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

-No. Impacts Rating

Brief Description of Result Pre-/Const ruction

Operation

Geographical Features

construction of transmission poles. Operation: No activity that will cause negative impact on topography and geographical features is anticipated.

3. Social Environment 3.1 Involuntary

Resettlement B - Construction: No resettlement is needed since the transmission line route avoided

the residential area. However, due to constructing transmission poles and substation, about 0.4 ha of land will be acquired. Operation: No activity that will cause involuntary resettlement is anticipated.

3.2 Vulnerable (poor households, female- headed households)

U - Construction: Vulnerability on affected people needs to be confirmed in conducting hearings with relevant administrative bodies and affected people. Operation: No activity that will affect the vulnerable is anticipated.

3.3 Indigenous and Ethnic Minority

U - Construction: Villagers in the project area belong to the Toba Batak ethnic group. Low rate of understanding of the Indonesian language by the villagers will affect the communication between villagers and the project owner/contractor. Operation: No activity that will affect indigenous and ethnic minority is anticipated.

3.4 Local Economy, Employment, and Livelihood

B+ B+ Construction/Operation: Positive impact such as creation of local employment is predicted.

3.5 Land Use and Utilization of Local Resources

C - Construction: Due to the construction of transmission poles, 0.4 ha of land will be converted from forest/agricultural land. Operation: No activity that will impact on land use or change of local resources is predicted.

3.6 Water Usage or Water Rights of Common

- - Construction/Operation: No activity that will give negative impact on water usage or water rights of commons is predicted.

3.7 Existing Social Infrastructures and Services

A+ - Construction: In order to improve accessibility for construction vehicles to the project area, the main road from Tarutung to the villages will be upgraded. It will help villagers to have access to Tarutung area. Operation: No activity that will affect existing social infrastructures and services is anticipated.

3.8 Social Institutions and Local Decision-making

- - Construction/Operation: No activity that will affect social institutions and local decision-making is anticipated.

3.9 Misdistribution of Benefit and Damage

- - Construction/Operation: No activity that will cause misdistribution of benefit and damage is anticipated.

3.10 Local Conflict of Interest

- - Construction/Operation: No activity that will cause local conflict of interest is anticipated.

3.11 Cultural Heritage - - Construction/Operation: No cultural heritage is confirmed within the project area.3.12 Landscape C - Construction: Construction of distribution poles will change the scenery.

Operation: No activity that will affect landscape is anticipated. 3.13 Gender C - Construction: Fair involvement in the process of land acquisition will be disturbed

due to gender bias, however, judging on the basis of current social status and women’s role, no gender concern is anticipated. Operation: No activity that will cause gender issues is anticipated.

3.14 Children’s Rights - - Construction/Operation: No activity that will affect children’s rights is anticipated.3.15 Communicable

Diseases such as HIV/AIDS

C - Construction: Inflow of construction workers from construction worker’s camp to local communities will raise the risks of communicable diseases. Operation: No activities raising the risk of communicable diseases in the local communities are anticipated.

3.16 Working Environment (includes work safety)

B - Construction: Inappropriate management of working environment will raise the risk of accident and decease. Operation: No activities raising the risk of working environment is anticipated.

4. Others 4.1 Accidents C - Construction: The effect of construction vehicles to the local community is

anticipated. Operation: No activities that will cause accidents are anticipated.

4.2 Global Warming - - Construction/Operation: No activities that will cause accidents is anticipatedRating: A: Serious impact is anticipated, B: Some impact is anticipated, C: Small impact is anticipated, +: Positive impact is anticipated, U: Extent of impact is unknown and examination is needed,impact may become clear as study progresses, -: No impact is anticipated Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 7-32 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

7.6 INITIAL ENVIRONMENTAL EXAMINATION (IEE)

7.6.1 TERMS OF REFERENCE (TOR) OF THE IEE

Based on the scoping, the TOR for the Component 1 and Component 2 is developed as shown in Table

7.6.1.

Table 7.6.1 TOR of the IEE Component 1: Hydropower Plants

No. Impacts Items for Study Methodology

1. Pollution Control 1.1 Air Pollution 1. Confirm the present condition in the

project area 2. Impacts during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles

1.2 Water Pollution 1. Confirm the present condition in the project area 2. Impacts during construction phase 3. Impact after diverting river water to the headrace channels

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles 3.Conduct water quality analysis in the project area of the Poring River in order to estimate the impact from the diversion of water

1.3 Waste 1. Confirm present condition in the project area 2. Impacts during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and location of construction worker’s camp/office

1.4 Noise and Vibration 1. Confirm present condition in the project area 2. Impact during construction phase

1.Collect existing information from relevant authorities 2. Confirm content, method, period, location, and area of construction works

2. Natural Environment

:2.1 Flora, Fauna, and Biodiversity

1. Collect present condition in the project area 2. Impacts during construction phase

1. Conduct field reconnaissance and hearing with villagers 2. Confirm content, method, period, location, area of construction works and location of construction worker’s camp/office

2.2 Hydrological Situation

1. Collect present condition in the project area and estimate maintenance flow for the Poring-1 and Poring-2 Hydropower Plants 2. Impacts during operation phase

1. Conduct water quality survey and fish survey in the Poring River in order to grasp the present condition at the upstream, intersection of the proposed intake weir and powerhouse, and downstream of the Poring-1 and the Poring-2 Hydropower Plants. Then, estimate the environmental maintenance flow for the Poring-1 and Poring-2 Hydropower Plants. 2.Confirm content, method, period, location, area of construction works and location of construction worker’s camp/office

2.3 Topography and Geological Features

1.Collect present condition in the project area 2.Impact during construction phase

1.Conduct field reconnaissance and hearing with relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles

3. Social Environment

3.1 Involuntary Resettlement

1.Confirm present condition in the project area

1. Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.2 Vulnerable (poor households, female-headed households)

1.Confirm present condition in the project area

1. Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

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Preparatory Survey on North Sumatra Mini 7-33 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

3.3 Indigenous and Ethnic Minority

1.Confirm present condition in the project area

1.Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.4 Land Use or Water Rights of Common

1.Confirm present condition in the project area

1.Hearing with relevant authorities and conduct field reconnaissance

3.5 Water Use and Utilization of Local Resources

1.Collect information in the project area 1.Hearing with relevant authorities and local community in the project area

3.6 Landscape 1.Collect information in the project area2.Impacts during construction and operation phases

1.Hearing with relevant authorities and conduct field reconnaissance 2.Confirm location of the proposed facilities

3.7 Gender 1.Confirm present condition in the project area

1.Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.8 Communicable Diseases such as HIV/AIDS

1.Impact during construction phase 1.Confirm location of construction worker’s camps/office

3.9 Working Environment (includes work safety)

1.Confirm legislations on working environment in Indonesia

1.Confirm information on similar project

4. Others 4.1 Accidents 1.Impact during construction phase 1.Confirm access road for construction vehicles and

conditions around the area 4.2 Global Warming 1.Impact during operation phase 1.Calculate the amount of CO2 to be reduced by

constructing the hydropower plant 4.3 Stakeholder

Meeting (SHM) 1.Organize SHM in compliance with the requirement of JICA and the Government of Indonesia

1.Individual meetings and focused group meetings to be organized at the project site during the conduct of census, loss inventory survey and socioeconomic survey 2. SHM at the village/district level to be organized after drafting the IEE report

Component 2: Transmission Lines

No. Impacts Items for Study Methodology

1. Pollution Control 1.1 Air Pollution 1.Confirm present condition in the

project area 2.Impacts during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles

1.2 Water Pollution 1.Confirm present condition in the project area 2.Impacts during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles

1.3 Waste 1.Confirm present condition in the project area 2.Impacts during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, area of construction works and location of construction worker’s camp/office

1.4 Noise and Vibration 1.Confirm present condition in the project area 2.Impact during construction phase

1.Collect existing information from relevant authorities 2.Confirm content, method, period, location, and area of construction works

2. Natural Environment 2.1 Flora, Fauna, and

Biodiversity 1.Collect information on flora, fauna and biodiversity in the project area 2.Confirm present condition in the project area 3.Impacts during construction and operation phases

1.Collect existing information from relevant authorities 2.Conduct plant, mammal and bird survey along the transmission line route 3.Confirm content, method, period, location, area of construction works and access road for construction vehicles

2.2 Topography and Geological Features

1.Collect present condition in the project area 2.Impact during construction phase

1.Conduct field reconnaissance and hearing with relevant authorities 2.Confirm content, method, period, location, area of construction works and access road for construction vehicles

3. Social Environment

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Preparatory Survey on North Sumatra Mini 7-34 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

3.1 Involuntary Resettlement

1.Confirm present condition in the project area

1.Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.2 Vulnerable (poor households, female-headed households)

1.Confirm present condition in the project area

1.Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.3 Landscape 1.Impact during construction phase 1.Confirm content, method , period, location, and area of construction works

3.4 Gender 1.Confirm present condition in the project area

1.Hearing with relevant authorities, collect information on similar project, conduct census, loss inventory survey and socioeconomic survey on affected households

3.5 Communicable Diseases such as HIV/AIDS

1.Impact during construction phase

1.Confirm location of construction worker’s camps/office

3.6 Working Environment (includes work safety)

1.Confirm legislations on working environment in Indonesia

1.Confirm information on similar project

4. Others 4.1 Accidents 1.Impact during construction 1.Confirm access road for construction vehicles and

conditions around the area 4.2 Stakeholder

Meeting (SHM) 1.Organize SHM in compliance with the requirement of JICA and the Government of Indonesia

1.Individual meetings and focused group meetings to be organized at the project site during conducting census, loss inventory survey, and socioeconomic survey 2. SHM at the village/district level to be organized after drafting IEE report

Source: JICA Survey Team

7.6.2 RESULTS OF THE IEE

The IEE was conducted by examining available data, hearing with stakeholders, carrying out site

reconnaissance, conducting site survey, and laboratory analysis. Overall result is described under (1)

summary of the IEE result. Then, the surveys which were specifically conducted in order to assess the

unknown impact at the time of scoping are described in the following sections in (2) Natural Environment

and (3) Social Environment.

(1) Summary of the IEE Result

According to the result of the IEE, predicted impacts of the Component 1 and Component 2 projects were

mostly the same as those identified by the scoping. Consequently, it is concluded that no significant

negative impact was predicted and the predicted impacts could be avoided or minimized by applying

countermeasures.

As for Component 1, the main negative impacts will be temporary and site-specific pollution such as air

pollution, water pollution, waste generation, and noise and vibration due to construction activities during

the construction phase. In addition, fishes and fishery will be affected due to the diversion of water from

the Poring River to the headrace channels in about 5 km section between the Poring-1 Intake Weir and the

Poring-2 Powerhouse during the operation phase.

Similar to Component 1, the main negative impacts of Component 2 will be temporary and site-specific

pollution such as air pollution, water pollution, waste generation, and noise and vibration due to

construction activities during the construction phase.

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Preparatory Survey on North Sumatra Mini 7-35 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Efforts were made to avoid any resettlement due to the construction of project facilities for both

Component 1 and Component 2. Consequently, there will be no resettlement resulting from the

construction of the project facilities.

The following is the summary of the result. The comparative table on the scoping result and the IEE result

is shown in Table 7.6.2. Based on the result, materials for appraisal were prepared.

Table 7.6.2 IEE Results Component 1: Hydropower Plants

No Impacts Rating Rating Brief Description PCo/C O PCo/C O

1. Anti-Pollution 1.1 Air Pollution C - C - Construction: Air pollution such as exhaust fumes from earthmoving equipment

as well as construction vehicles associated with the facilities of hydropower plant construction is anticipated. Considering the scale of construction activities, the impact is temporary and site specific, thus not significant. Operation: No activity that will cause air pollution is anticipated.

1.2 Water Pollution B U B - Construction: Temporary water pollution due to concrete mixing, aggregate collection and excavation is anticipated. In addition, temporary water pollution from contractor’s employee’s camp/office is anticipated. Operation: Since there is no direct discharge of wastewater to the section where the water would be decreased due to the diversion of water, negative impact of the diversion on water quality is not significant (see details in the following section (2) Natural Environment).

1.3 Waste B - B - Construction: Construction waste soil will be generated mainly from the powerhouse construction site. Vegetable debris will be generated at the time of land clearance for the land of powerhouse, headrace channel, intake weir, and access road. Also, waste such as kitchen scraps and human waste will be generated from worker’s camps and construction office. Operation: No activity that will cause waste is anticipated.

1.4 Soil Contamination

- - - - Construction: No soil contamination is predicted. Operation: No soil contamination is predicted.

1.5 Noise and Vibration

C C C - Construction: Noise and vibration resulting from construction activities are anticipated. Disturbance from noise and vibration is to be predicted particularly at the construction site of headrace channel near the residential area. Operation: Some noise is predicted near the powerhouse. However, negative impact is not anticipated since it is located far from the residential area.

1.6 Ground Subsidence

- - - - Construction/Operation: No activity that will cause ground subsidence is anticipated.

1.7 Offensive Odor - - - - Construction/Operation: No activity that will cause offensive odor is anticipated.

1.8 Bottom Sediment - - - - Construction/Operation: No activity that will affect bottom sediment is anticipated.

2. Natural Environment 2.1 Protected Area - - - - Construction/Operation: The project area is not located in a protected area. 2.2 Flora, Fauna and

Biodiversity U U C B Construction: No endangered species were confirmed. Some impacts on existing

habitats will be anticipated due to changing land use patterns; however, the impacts are site-specific. Operation: The decrease of water due to diversion of river water from the Poring River to the headrace channels affects the population and sizes of fish species. (see details in the following section (2) Natural Environment).

2.3 Hydrological Situation

- U - B Construction: No activity that will affect hydrological situation is anticipated. Operation: Change in the hydrological situation in the section where the water from the Poring River is diverted to the headrace channel will affect the population and size of fish species.

2.4 Topography and Geographical Features

B - B - Construction: Topography and geographical features will be affected due to the construction of powerhouse, headrace channel, intake weir, and access road. Operation: No activity that will affect topography and geographical features is anticipated.

3. Social Environment 3.1 Involuntary B - B - Construction: No resettlement is needed since the location of all facilities

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Preparatory Survey on North Sumatra Mini 7-36 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Resettlement avoided the residential area. However, due to construction of the facilities and access road, about 40 ha of land will be acquired. Operation: No activity that will cause involuntary resettlement is anticipated.

3.2 Vulnerable (poor households, female-headed households)

U - B - Construction: Land acquisition for the construction of project facilities will decrease the income generated from the land. Operation: No activity that will affect the vulnerable is anticipated.

3.3 Indigenous and Ethnic Minority

C - C - Construction: The Toba Batak is a major ethnic group and Batak is their native language in the project area. Although the literacy ratio is high ranging from 60% to 97%, the ratio of understanding the official document in Indonesian remains low at around 30%. Consideration shall be given for communication. Operation: No activity that will affect indigenous and ethnic minority is anticipated.

3.4 Local Economy, Employment, Livelihood

B+ - B+ A+ Construction: Positive impact such as creation of local employment is predicted.Operation: No activity that will affect local economy, employment and livelihood is anticipated. Upgraded road which has been constructed during the construction phase for accessing the construction site will enhance the vital mobilization of people and goods and contribute to the economic development in the project area.

3.5 Land Use and Utilization of Local Resources

C - C C Construction: Due to the project, 40 ha of land will be converted from plantation/agricultural land. Operation: Due to the diversion of water from the Poring River to the headrace channels, the fish in the diversion section will decrease in number and size which will affect the villager’s fishing opportunities.

3.6 Water Usage or Water Rights of Common

U U C C Construction: There is no building infrastructure such as irrigation or water supply in the section where the water is to be diverted to the headrace channel from the Poring River. Moreover, there are no activities such as tourism or boat transportation in the section. However, construction activities in and along the Poring River will affect the villager’s fishing opportunity. Operation: In the section where the water is to be diverted from the Poring River to the headrace channel, the number and size of fish are predicted to be smaller. Consequently, it will affect the villager’s fishing opportunities.

3.7 Existing Social Infrastructures and Services

A+ - A+ - Construction: In order to improve accessibility of construction vehicles to the project area, the main road from the villages to the direction of Tarutung will be upgraded. It will help the villagers’ accessibility to Tarutung area. Operation: There is no activity that will affect existing social infrastructures and services.

3.8 Social Institutions and Local Decision-making

- - - - Construction/Operation: No activity that will affect social institutions and local decision-making is anticipated.

3.9 Misdistribution of Benefit and Damage

- - - - Construction/Operation: No activity that will cause misdistribution of benefit and damage is anticipated.

3.10 Local Conflict of Interest

- - - - Construction/Operation: No activity that will cause local conflict of interest is anticipated.

3.11 Cultural Heritage - - - - Construction/Operation: No cultural heritage is confirmed within the project. 3.12 Landscape C - C - Construction: Construction of the facilities such as power house and intake weir

will change the scenery. However, the project is located in a remote area where there are no touristic activities; the impact on the landscape is not significant. Operation: No activity that will affect landscape is anticipated.

3.13 Gender C - - - Construction: No unfair custom for women on landownership or social participation is confirmed in the villages of the project area. Accordingly, no activity that will cause gender issues is anticipated. Operation: No activity that will cause gender issues is anticipated.

3.14 Children’s Rights - - - - Construction/Operation: No activity that will affect children’s rights is anticipated.

3.15 Communicable Diseases such as HIV/AIDS

C - C - Construction: Inflow of construction workers from construction worker’s camp to local communities will raise the risks of communicable diseases. Operation: No activities raising the risk of communicable diseases in the local communities are anticipated.

3.16 Working Environment (includes work safety)

B - B - Construction: Inappropriate management of working environment will raise the risk of accident and decease. Operation: No activities raising the risk of working environment is anticipated.

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Preparatory Survey on North Sumatra Mini 7-37 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

4. Others 4.1 Accidents C - C C Construction: The effect of construction vehicles to the local community is

anticipated. Operation: There is a risk for villagers to fall down into the open headrace channel.

4.2 Global Warming - B+ - B+ Construction: CO2 emission from construction vehicles is not significant. Operation: Since the hydropower plant uses renewable energy, it will contribute to reduce CO2 emission.

Component 2: Transmission Lines

No. Impacts Rating Rating based

on IEE Result

Brief Description of Result

PCo/C O PCo/C O

1. Pollution Control 1.1 Air Pollution C - C - Construction: Air pollution such as exhaust fumes from earthmoving equipment

as well as construction vehicle associated with the tower construction is anticipated. Considering the scale of the construction activities, the impact is temporary and site specific, thus not significant. Operation: No activity that will cause air pollution is anticipated.

1.2 Water Pollution C - C - Construction: Temporary water pollution due to concrete mixing at the substation and excavation for digging hole to bury transmission pole is anticipated. In addition, temporary water pollution from contractor’s employee’s camp/office is anticipated. Considering the scale of construction activities, the impact is temporary and site specific, thus not significant. Operation: No activity that will cause water pollution is anticipated.

1.3 Waste C - C - Construction: Soil will be excavated for burying construction pole and installing transformer at the substation; however, the soil will be backfilled and no waste soil will be generated. Waste such as kitchen scraps and human waste will be generated from the worker’s camps and construction office. Considering the scale of construction activities, the impact is not significant. Operation: No activity that will cause waste is anticipated.

1.4 Soil Contamination

- - - C Construction: No soil contamination is predicted. Operation: Inappropriate management of transformer will cause oil leakage. Consequently, it will contaminate soil.

1.5 Noise and Vibration

C - C - Construction: Noise and vibration resulting from construction activities are anticipated. The main cause of noise and vibration will be generated at the time of digging hole for burying transmission pole. Considering the scale of construction activities, the impact is not significant. Operation: No activity that will cause noise and vibration is anticipated.

1.6 Ground Subsidence

- - - - Construction/Operation: No activity that will cause ground subsidence is anticipated.

1.7 Offensive Odor - - - - Construction/Operation: No activity that will cause offensive odor is anticipated.

1.8 Bottom Sediment - - - - Construction/Operation: No activity that will affect bottom sediment is anticipated.

2. Natural Environment 2.1 Protected Area - - - - The project area is not located in a protected area. 2.2 Flora, Fauna and

Biodiversity U - C - Construction: After conducting mammal survey and bird survey along the

transmission line route as well as carrying out hearing with relevant administrative bodies, no primary forest was confirmed in the project area. Low biodiversity value was observed in the project area because the area has been disturbed and the habitats have been degraded in previous years due to human encroachment in the area. Along the proposed line route, two species categorized as vulnerable, one species categorized as endangered species, and one species categorized as critically endangered under IUCN Red List were found. The upgrade of the access road would cause illegal logging. 14 mammal species (4 endangered, 7 vulnerable, 3 near threatened) listed in IUCN Red List were found. Impact for birds are not significant since the birds are small in size and the TL will be constructed at a height which the birds do not migrate. These are not endemic to the project area. Considering the scale of construction, in which the transmission line route will not change the shape of the land entirely and the construction activities will be site specific and temporary, the impact would not be significant.

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Operation: No activity that will cause negative impact on flora, fauna and biodiversity is anticipated.

2.3 Hydrological Situation

- - - - Construction/Operation: No activity that will cause negative impact on hydrological situation is anticipated.

2.4 Topography and Geographical Features

C - C - Construction: Topography and geographical features will be affected due to the construction of transmission poles. Considering the scale of construction activities, the impact is temporary and site specific, thus not significant Operation: No activity that will cause negative impact on topography and geographical features is anticipated.

3.1 Involuntary Resettlement

C - C - Construction: No resettlement is needed since the transmission line route avoided the residential area. However, due to the construction of transmission poles and substation, about 0.4 ha of land will be acquired. Operation: No activity that will cause involuntary resettlement is anticipated.

3.2 Vulnerable (poor households, female-headed households)

U - C - Construction: The average income in most of the project area is under the minimum income set in North Sumatra Province. However, the impact to the affected households is not significant (only 1 m² will be affected due to the construction of a pole at a time) Operation: No activity that will affect the vulnerable is anticipated.

3.3 Indigenous and Ethnic Minority

U - C - Construction: The Toba Batak is the major ethnic group and the Batak language is their native language in the project area. Although the literacy ratio is high ranging from 60% to 97%, the ratio of those who can understand official documents in Indonesian remains low at around 30%. Consideration shall be given for communication. Operation: No activity that will affect indigenous and ethnic minority is anticipated.

3.4 Local Economy, Employment, Livelihood

C+ - C+ A+ Construction: Positive impact such as creation of local employment is predicted. Operation: No activity that will affect local economy, employment, and livelihood is anticipated. Upgraded road which is constructed during the construction phase for accessing construction site will enhance the mobilization of people and goods and contribute in the economic development of the project area.

3.5 Land Use and Utilization of Local Resources

C - C - Construction: Due to the construction of transmission poles, 0.4 ha of land will be converted from forest/agricultural land. The acquired area is sparse, thus the impact on each affected area is not significant. Operation: No activity that will impact on land use or change the local resources is predicted.

3.6 Water Usage or Water Rights of Common

- - - - Construction/ Operation: No activity that will cause negative impact on water usage or water rights of commons is predicted.

3.7 Existing Social Infrastructures and Services

A+ - A+ - Construction: In order to improve accessibility of construction vehicles to the project area, the main road from Tarutung will be upgraded. It will help villagers to have access to Tarutung area. Operation: No activity that will affect existing social infrastructures and services is anticipated.

3.8 Social Institutions and Local Decision-making

- - - - Construction/Operation: No activity that will affect social institutions and local decision-making is anticipated.

3.9 Misdistribution of Benefit and Damage

- - - - Construction/Operation: No activity that will cause misdistribution of benefit and damage is anticipated.

3.10 Local Conflict of Interest

- - - - Construction/Operation: No activity that will cause local conflict of interest is anticipated.

3.11 Cultural Heritage - - - - Construction: No cultural heritage is confirmed within the project area. Operation: No activity that will affect cultural heritage is anticipated

3.12 Landscape C - C - Construction: Construction of distribution poles will change the scenery. However, the transmission line will be located either along the side of the public road or remote location from the residential area; thus, the predicted impact is not significant. Operation: No activity that will affect the landscape is anticipated.

3.13 Gender C - - - Construction: Fair involvement in the process of land acquisition will be disturbed due to gender bias; however, judging on the basis of current social status and women’s role, no gender concern is anticipated. Operation: No activity that will cause gender issues is anticipated.

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3.14 Children’s Rights - - - - Construction/Operation: No activity that will affect children’s rights is anticipated.

3.15 Communicable Diseases such as HIV/AIDS

C - C - Construction: Inflow of construction workers from the construction worker’s camp to local communities will raise the risks of communicable diseases. However, considering the scale of construction activities, the impact is temporary and site-specific, thus not significant Operation: No activities that will raise the risk of communicable diseases in the local communities are anticipated.

3.16 Working Environment (includes work safety)

C - C - Construction: Inappropriate management of working environment will raise the risk of accident and death. Operation: No activities that will raise the risk of accident and decease in the working environment are anticipated.

4.1 Accidents C - C - Construction: The effect of construction vehicles to the local community is anticipated. Operation: No activities that will cause accidents are anticipated.

4.2 Global Warming - - - - Construction/Operation: No activities that will cause accidents are anticipatedSource: JICA Survey Team

(2) Natural Environment

1) Flora

Component 1 (Hydropower Plants): According to the UKL-UPL (Environmental Management and

Monitoring Plan) prepared by the North Sumatra University (USU) and certified by the North Tapanuli

District Government in 2013, 71 species were found in the proposed project construction area (Location

I) or residential area (Location II) in Component 1. No threatened species, comprising of critical species

(CR), endangered species (EN), and vulnerable species (VU) under the IUCN Red List or Attachment to

the Presidential Decree No.7 1999 on Conservation of Flora and Fauna, were found in Location I.

Component 2 (Transmission Lines): The sampling survey was conducted during the wet season (April

2015) and dry season (September 2015). Survey methods are: 1) direct sampling at eight locations along

the proposed transmission lines, 2) observations, 3) identification of unknown plants at the laboratory of

Plant Ecology, Department of Ecology, North Sumatra University, and 4) interviews with local people.

As for the land cover vegetation along the transmission line route, it was found that it was dominated by

shrubs, fields, and settlements; and there is a primary forest. About 154 species of plants are scattered

along the path of observation. Based on the literature review, two species of plants that are listed in the

Attachment to the Presidential Decree No.7 1999 on Conservation of Flora and Fauna, and two species

categorized as vulnerable, one species categorized as endangered, and one species categorized as

critically endangered under the IUCN Red List were found.

These identified plants are not endemic plants in the project area. These plants are widely distributed in

various forest areas in Indonesia as well as in the tropical forests. With the efforts to avoid these identified

species by rerouting the transmission line, the impact on the flora in the project area of Component 2 can

be minimized. Accordingly, predicted impact on the flora is not significant.

2) Fauna

Component 1 (Hydropower Plants): According to the certified UKL-UPL prepared by USU 2013, 15

mammals and 7 aves were identified in the area of Component 1. Six out of 15 mammals identified

through hearing with villagers that are categorized as threatened species (CR: critically endangered, VU:

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Preparatory Survey on North Sumatra Mini 7-40 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

vulnerable, EN: endangered) in IUCN Red List or 12 mammals fall into the protected list in Decree No.7.

After carrying out hearing with villages in the area of Component 1 in April 2015, it was confirmed that

these species were used to be in the project area; however, they have not been witnessed in the last ten

years. Accordingly, it would be assumed that no threatened species are confirmed in the Component 1

area, however, is better to prepare mitigation measures such as prohibit hunting by the construction

workers in the project area.

Component 2 (Transmission Lines): The sampling survey was conducted during the wet season (April

2015) and dry season (September 2015). Survey methods are: 1) observations, 2) identification of

unknown mammals at the laboratory of Plant Ecology, Dept. of Ecology, North Sumatra University and

3) interviews with local people.

As for mammals, 53 species were found along the proposed transmission line routes in which 12 species

are listed in the Attachment to the Presidential Decree No.7 1999 on Conservation of Flora and Fauna.

Among the 12 species, only three species are actually observed at the field, two species could not be

specified due to insufficient data, and information on seven species were collected from public interviews.

On the other hand, 14 mammals under the UNCN Red List were found comprising four endangered

species, eight vulnerable species, and three nearly threatened species. Only six species were actually

observed at the field, two species could not be specified due to insufficient data, and information on six

species were collected from public interviews.

Some of the habitat of identified species will be permanently disturbed due to cutting of trees for the

construction of the transmission lines and temporarily due to the construction activities. However, the

scale of impact due to the conversion of about 0.4 ha of forest/agricultural land to project land for burying

transmission line pole with 1 m² land in each pole along the 30 km of linger area and cutting of trees of 5

m width along the transmission line route will not change the shape of the land entirely; and the

construction activities will be site specific and temporary; therefore, it is considered that the project will

not affect/impact significantly on the survival of living things in the project area.

3) Impact Resulting from the Water Diversion from the Poring River to the Headrace Channel

Due to the diversion of water from the Poring River to the headrace channel of the Poring-1 and Poring-2

mini hydropower plants, the river discharge in the 5 km section from the Poring-1 Intake Weir to the

Poring-2 Mini Hydropower Plant will be decreased. Since there is no specific regulation on the

maintenance flow of hydropower plants in Indonesia, the electric generation guideline (Ministry of Land,

Infrastructure, Transport and Tourism, Japan, 1988) will be applied to set the maintenance flow for the

Poring-1 and Poring-2 mini hydropower plants. Based on the guideline, the maintenance flow for the

project is to be set at about 0.31 m3/s (see Chapter 4.2.1). In this section, the impact resulting from the

water diversion will be discussed.

In order to assess the impact resulting from the diversion of water from the Poring River to the headrace

channel, the following items were studied by conducting field survey and hearings with the local people

and authorities, and carrying out literature review. The studied items and the results of the study are

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Preparatory Survey on North Sumatra Mini 7-41 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

summarized in Table 7.6.3.

Table 7.6.3 Summary of the Survey Result No Items Point to be assessed Method of Study Result 1 Fish and

Fishery Conservation concern, importance of habitat in the project area

- Identify fish species from the Poring River during the dry season and wet season using appropriate fishing methods and working with local fisherman

Two fish species were found in the project area of the Poring River. Both are not endemic to the region and not listed in the IUCN Red List. Abundance of fishes is very low due to geographic feature of the project area and over fishing by local people.

Socioeconomic importance to local community and fisheries in the downstream of the project site

- Interview with village heads and local people by conducting focused-group discussions

There is no commercial fishing. There is no fishing point after the downstream of the project site due to difficult accessibility. Fishing is a hobby and for domestic consumption.

2 Water Quality Water quality and wastewater discharge amount

- Confirm the location of wastewater discharge to the project area of the Poring River - Analyze the water quality at the laboratory

There is no location of discharged domestic or industrial wastewater directly into the project area of the Poring River. The result of water quality analysis in the dry and wet season satisfies the water quality standards.

3 Water Supply Water level decrease to water supply facility

- Confirm the location of water supply facility within the project area

There is no water supply facility located in the project area of the Poring River

4 Irrigation Water level decrease to irrigation system

- Confirm the location of irrigation facility within the project area

There is no irrigation facility located in the project area of the Poring River

5 Underground Water

Water level decrease to water supply facility

- Confirm the location of the facility using underground water within the project area

There is no water supply facility using underground water in the project area

6 Boat Transportation

Water level decrease to boat transportation

- Confirm the location of boat transportation within the project area

There is no boat transportation in the project area of the Poring River

7 Tourism Water level decrease to aesthetics and touristic activities

- Confirm the location of tourism site or facility within the project area

There is no location or facility used for tourism in the project area of the Poring River

Source: JICA Survey Team

Based on the study, it is concluded that the negative impacts on the items from No.3 to No.7 are not

anticipated. Accordingly, the result of the impact on the fish and fishery and water quality are discussed

in this section.

a. Fish and Fishery

- Fish Species

The fish species survey was conducted at the six sites during the two seasons, the wet season (from 26 to

28 of May 2015) and the dry season (from 10 to 14 of August 2015). The location of the six sampling

sites is shown in Table 7.6.4. The result of the collected fish species is shown in Table 7.6.5.

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Preparatory Survey on North Sumatra Mini 7-42 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.6.4 Location of Fish Species Survey Location Description

Lubuk* Sihopar Intake Weir Poring-1 Lubuk NIpis Intake Weir Poring-1

Lubuk Pandan Power House Poring-1 Lubuk Bangal Intake Weir Poring-2**

Lubuk Sitorngom Power House Poring-2 Lubuk Batnunbolon One of the fishing points of villagers

*Lubuk means a fishing point in the local language (Toba Batak language) **The survey was conducted based on the old layout with Poring-2 Intake Weir. However, after the review of the facility layout, Poring-2 Intake Weir is decided not to be constructed. Source: USU

Table 7.6.5 Result of Identified Fish Species Wet Season

Location

Condition of Site Fish Species

pH Temperature

(°C) DO (mg/L)

Conductivity(S)

Velocity (m/s)

Local Name Scientific Name Number of Catch

Lubuk Sihopar 7.5 23 7.3 20 1.2 Ikan Garing Neolissochilus sumatranus 3

Lubuk NIpis 7.6 25 7.2 22 0.6 - - 0

Lubuk Pandan 7.2 27 7,2 20 0.9 Ikan Garing Neolissochilus sumatranus 1

Lubuk Bangal 7.4 26 7.2 20 1.0 Ikan Garing Neolissochilus sumatranus 6

Lubuk Sitorngom 7.3 26 7.3 21 1.2 Ikan Garing Neolissochilus sumatranus 3

Ikan Garing Tar tambra 1

Lubuk Batnunbolon 7.3 29 7.2 23 2.0-3.5 Ikan Garing Neolissochilus sumatranus 12

Source: USU Dry Season

Location

Condition of Site Fish Species

pH Temperature

(°C) DO (mg/L)

Conductivity(S)

Velocity (m/s)

Local Name Scientific Name Number of Catch

Lubuk Sihopar 7.3 22 7.4 21 1.0 Ikan Garing Neolissochilus sumatranus 2

Ikan Garing Tar tambra 4

Lubuk NIpis 7.4 23 7.3 21 0.8 - - 0Lubuk Pandan 7.3 22 7.3 21 1.2 - - 0Lubuk Bangal 7.4 22 7.5 22 1.2 Ikan Garing Neolissochilus sumatranus 1

Ikan Garing Tar tambra 3

Lubuk Sitorngom 7.7 22 7.3 21 1.5 Ikan Garing Tar tambra 3

Lubuk Batnunbolon 7.4 23 6.9 22 2.7 - - 0Source: USU

The result of the fish species survey at five locations around the intake weir and powerhouse of the

Poring-1 and Poring-2 mini hydropower plants during the rainy season showed that the number of catch

was relatively low with a total of 26 fishes. Furthermore, the weight of each fish was quite small ranging

from 16.6 g to 143.1 g and only two fishes exceeded 100 g. The survey result at the same location during

the dry season indicated that the number of catch is lower (13 fishes) than that during the rainy season and

the size of fish is also smaller ranging from 9.3 g to 68.3 g. This fact shows that the abundance of fish in

the Poring River is low. In particular, it is remarked that even under the present condition, the population

and size of fishes become small during the dry season when the discharge is low.

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Preparatory Survey on North Sumatra Mini 7-43 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

In the survey, two fish species were identified, namely, Tor tambra7 and Neolissochilus sumatranus. Both

species are not listed as vulnerable or endangered in the IUCN Red List and they are not ascent type of fish.

There is no specific study on the required maintenance flow for these identified fish species; however, these

types of fish are categorized as fish species living in fast flowing water. There are several studies reporting that

this type of fish is identified with water discharge of more than 25 L/s (or 0.025 m3/s), with dissolved oxygen

(DO) of 6-8 ppm, and an optimum discharge for breeding fish of 50-100 L/s (or 0.05 – 0.1 m3/s).8

Considering the fact that the maintenance flow rate is set at 0.31 m3/s, the discharge of water from the Poring-1

and Poring-2 mini hydropower plants would satisfy the optimum discharge for breeding the fish species.

However, because of the undulating topography of the Poring River and the presence of many boulders in the

river, the water route is changed in a complex way. It is predicted that the set maintenance flow of 0.31 m3/s

(or about 97% of drought water discharge) would partly make the water flow significantly lower.

Consequently, the population and size of the fish species in the section wherein the water discharge will

decrease due to the diversion would be affected.

- Fishery and Local Community

The information on the villagers who practice fishing in the Poring River was obtained from the

information office of the chief secretary of the village and also from some local community leaders. The

names of fishermen were also obtained from the village of Siantar Naipospos and Pardomuan Nauli. The

total number of interviewed persons is 24 comprising 21 persons from Siantar Naipospos Village and

three persons from Pardomuan Nauli. Interviewees were chosen randomly.

Based on the interviews and information from the villagers in the two surveyed villages, it was confirmed

that none of them catch fish in the river for commercial purpose. Basically, they catch fish for domestic

consumption and if they catch a large number of fish, it will be sold to other villagers. Some of the

villagers mentioned that they catch fish just for entertainment or hobby after work. Summary of the catch

in the Poring River obtained from the interview is shown in Table 7.6.6.

The methods of fishing are with net, hook and lines. Villagers go for fishing not all the time or everyday,

but 2 to 3 times in a week or once in a week.

After the construction of the Poring-1 Mini Hydropower Plant and the Poring-2 Mini Hydropower Plant,

the number of fishes as well as the size of fishes are predicted to be smaller. Accordingly, it would cause:

1) losing one of the sources of protein for domestic consumption, 2) spending extra money to buy fish for

domestic consumption, 3) losing additional income opportunity for selling extra catch to neighbors, and

4) losing location for recreation after work. 7 Tor tambra is categorized as DD (Data Deficient) in the IUCN Red List 8 Haryono, Tjakrawidjaja, A.H. 2009. Bioekologi ikan tambra sebagai dasar dalam proses domestikasi dan reproduksinya. Proses domestikasi dan reproduksi ikan tambra yang telah langka langka menuju domestikasinya:17-36. LIPI Kiat, Ng Chi. 2004. The king of the river mahseer in Malayan and the region. Inter Sea Fishery, Malaysia. Kottelat, M., A.J. Whitten, S.N. Kartikasari & S. Wirjoatmodjo. 1993. Freshwater Fishes of Western Indonesia and Sulawesi. Periplus Editions Limited. 1-291+84 plates Weber, M. & L.F. de Beaufort. 1913-1916. The Fishes of the Indo-Australian Archipelago I-XI. E.J. Brill Ltd., Leiden.

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According to the hearings in the focused group meeting, all participants agreed to support the project if

the project would consider measures for community development as compensation for the loss of fish

catch. Main requests for community development are: 1) improve access road from the village to Adian

Koting District (towards Tarutung direction), 2) electrification in the village, and 3) improve domestic

water supply facilities in the village.

Table 7.6.6 Type of Fish, Volume of Catch, and Economic Value Type of Fish

Method of Catch Volume of

Catch, kg/timeEconomic Value

kg/Rp (US$) Frequency of Fishing

Local Name Scientific Name Ikan Garing Neolissochilus sumatrana Net/hook and lines 0.25 kg to 4 kg 50,000 (3.7) to

60,000 (4.5) 2-3 times a week, Once a week

Ikan Jurung/ Ihan Batak

Tor Tambroides Hook and lines 1 kg to 2 kg 50,000 (3.7) to 60,000 (4.5)

2-3 times a week, Once a week

Ikan Dundung Anguilla bicolour Hook and lines/net 0.1 kg to 2 kg 50,000 to 60,000 2-3 times a week, Once a week

Ihan Lappung N/A Hook and lines 0.1 kg to 2 kg 50,000 (3.7) 2-3 times a week, Once a week

Ihan Lelan Osteochilus vittatus C.V Hook and lines 0.5 kg to 2 kg 50,000 (3.7) Once a week Source: JICA Survey Team

- Conclusion

Considering the fact that the set maintenance flow rate of 0.31 m3/s, it will satisfy the required discharge

for breeding the fish species. The topography of the Poring River does not enable fish species

(particularly large size of fish) to migrate from one area to another area for feeding and this will likely

reduce the population and size of the fish. The identified fish species are not endemic to the region and

they are considered to be popular in the upstream and downstream of the project site, where geography of

the area is very similar to the project area. Consequently, it is considered that the impact due to the

diversion of water from the intake weir of the Poring-1 Mini Hydropower Plant to the Poring-2

Powerhouse would not be significant on the fish species in the local area or population of fish.

The mitigation measures against the loss of fishing site and loss of fish catch shall be considered taking

into account the villagers’ requests. Since the losses involve not the fishermen engaged in commercial

basis particularly but the whole community members living near the affected section in the Poring River,

it is recommended to provide a means of assistance for community development in exchange of

compensating the losses. Some of the requests such as improving the access road to Tarutung is already

incorporated in the project framework. In addition to this, alternative means to supplement protein such as

constructing fish culture or introducing effective method for breeding livestock shall be developed during

the operation phase. Using the corporate social responsibility (CSR) scheme is one of the realistic options.

b. Water Quality

Water quality sampling was conducted at the nine sites during the two seasons, i.e., wet season (from 25

to 27 April 2015) and dry season (from 10 to 13 August 2015). The location of the nine sampling sites is

shown in Table 7.6.7. The result of water sampling is shown in Table 7.6.8.

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Preparatory Survey on North Sumatra Mini 7-45 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.6.7 Location of the Water Sampling Location Description

Site 1 Poring-1 Intake Weir Site 2 Poring-1 Powerhouse Site 3 Poring-2* Intake Weir Site 4 Poring-2 Powerhouse Site 5 Public Bathroom in Dusum Limus Site 6 Aek Pandolungan (tributary) in Dusum Lobu Site 7 Aek Pandolungan (tributary) in Dusum Lobu Haminjon Site 8 Pancuran (public water supply space) in Dusun Lobu Haminjon Site 9 Public bathroom in Dusum Lobu Haminjon

*The survey was conducted based on the old layout with Poring-2 Intake Weir. However, after the review of the facility layout, Poring-2 Intake Weir is decided not to be constructed Source: USU

Table 7.6.8 Results of the Water Sampling Wet Season

Parameters Unit of

Measurement National Standard*

Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Site 9

Physical Temp. C ± 3 28.0 28.0 28.5 29.0 27.0 27.0 28.4 28.3 29.0 Odor - - No

odorNo

odorNo

odorNo

odorNo

odorNo

odorNo

odor No

odor No

odorTDS mg/l 1,000 231.7 228.5 267.5 299.4 146.8 142.3 205.8 226.7 TSS mg/l 50 34.9 32.6 31.5 30.8 32.5 34.7 33.6 31.4 32.8 pH - 6-9 7.2 6.6 7.1 7.3 6.3 7.2 6.7 6.4 6.4 Color PtCo - 4.2 <3.10 4.8 4.1 <3.10 <3.10 <3.10 <3.10 3.88 Turbidity NTU - 0.8 0.4 0.6 0.4 0.3 0.3 0.6 0.9 0.4 Conductivity s - 20 20 21 22 21 20 22 21 20 Chemical Iron (Fe) mg/l 1 <0.08 <0.08 <0.08 0.10 <0.08 <0.08 <0.08 <0.08 <0.08Fluoride (F) mg/l 1.5 0.08 0.05 0.05 0.09 0.08 0.12 0.09 0.12 0.06 Cadmium (Cd) mg/l 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01DO mg/l >4 7.3 7.2 7.4 7.2 7.1 7.4 7.3 7.2 7.3 Alkalinity (CaCO3) mg/l - 36.52 31.44 41.62 49.55 32.17 38.56 44.56 52.76 45.91Chloride (Cl) mg/l - 24.51 19.67 32.75 28.61 17.62 22.45 28.39 37.11 22.63Chromium VI (Cr6+)

mg/l 0.05 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04

Manganese (Mn) mg/l - 0.10 0.09 0.07 0.12 0.05 0.06 0.05 0.06 0.18 Ammonia (NH3-N) mg/l - 0.28 0.25 0.27 0.26 0.20 0.18 0.17 0.18 0.14 Nitrate (NO3-N) mg/l 10 8.37 7.56 7.63 8.25 4.23 3.69 4.56 4.14 8.20 Nitrite (NO2-N) mg/l 0.06 0.03 0.02 <0.01 0.03 <0.01 <0.01 <0.01 <0.01 0.03 Zinc (Zn) mg/l 0.05 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Sulfate (SO4) mg/l - 27.51 26.34 33.26 37.11 28.66 20.10 16.23 27.12 16.66Lead (Pb) mg/l 0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03MBAS mg/l 0.2 0.09 0.09 0.05 0.08 0.08 0.03 0.08 0.03 0.15 Phenol mg/l 0.001 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006Organic (KMnO4) mg/l - 3.11 3.05 4.26 5.17 3.20 2.76 3.86 4.19 2.24 Total Phosphate (PO4)

mg/l - 0.10 0.07 0.10 0.07 0.06 0.04 0.03 0.04 0.03

Microbiological Total Coliform Jml/100 ml 5,000 286 254 325 417 188 115 205.8 266.9 295 Faecal Coliform Jml/100 ml 1,000 104 97 177 227 89 63 112 161 116 *Management of Water Quality and Water Pollution Control Class II, PPRI No.82, 2001 Source: USU Dry Season

Parameters Unit of

Measurement National Standard*

Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Site 9

Physical Temp. C ± 3 22.0 22.0 22.0 22.0 24 23 22 22 24 Odor - - No

odorNo

odorNo

odorNo

odorNo

odorNo

odorNo

odor No

odor No

odor

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Preparatory Survey on North Sumatra Mini 7-46 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

TDS mg/l 1,000 0.09 0.09 0.09 0.09 0.10 0.09 0.09 0.09 0.10TSS mg/l 50 35.2 33.9 30.4 29.8 30.1 32.2 34.0 32.8 33.0pH - 6-9 7.3 7.3 7.4 7.4 7.1 7.4 7.4 6.8 6.7 Color PtCo - 4.3 <3.10 4.5 3.9 <3.10 <3.10 0.7 0.10 3.90Turbidity NTU - 0.10 0.6 0.5 0.3 0.4 0.4 21 22 0.4 Conductivity s - 21 21 22 21 21 21 22 Chemical Iron (Fe) mg/l 1 <0.08 <0.08 <0.08 0.10 <0.08 <0.08 <0.08 <0.08 <0.08Fluoride (F) mg/l 1.5 0.09 0.06 0.06 0.10 0.09 0.13 0.08 0.10 0.05Cadmium (Cd) mg/l 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01DO mg/l >4 7.4 7.3 7.5 7.3 7.2 7.3 7.4 7.3 7.1 Alkalinity (CaCO3) mg/l - 35.42 32.90 42.20 50.13 33.09 39.08 45.60 53.42 46.10Chloride (Cl) mg/l - 25.05 20.07 31.78 29.09 18.20 23.10 29.89 38.09 23.56Chromium VI (Cr6+)

mg/l 0.05 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <0.04

Manganese (Mn) mg/l - 0.11 0.10 0.09 0.15 0.06 0.07 0.06 0.07 0.20Ammonia (NH3-N) mg/l - 0.30 0.27 0.30 0.28 0.21 0.19 0.18 0.19 0.16Nitrate (NO3-N) mg/l 10 8.42 7.62 7.68 8.31 3.90 2.25 4.56 4.19 9.09Nitrite (NO2-N) mg/l 0.06 0.03 0.03 <0.01 0.04 <0.01 <0.01 <0.01 <0.01 0.04Zinc (Zn) mg/l 0.05 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Sulfate (SO4) mg/l - 28.20 27.10 34.40 36.21 28.70 20.19 17.08 28.16 17.12Lead (Pb) mg/l 0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03MBAS mg/l 0.2 0.10 0.10 0.06 0.009 0.09 0.04 0.09 0.04 0.18Phenol mg/l 0.001 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006Organic (KMnO4) mg/l - 3.15 3.11 4.34 5.28 3.34 2.80 3.90 4.21 2.35Total Phosphate (PO4)

mg/l - 0.09 0.08 0.15 0.09 0.07 0.05 0.04 0.05 0.04

Microbiological Total Coliform Jml/100 ml 5,000 290 262 332 423 190 123 204.2 256.9 303 Faecal Coliform Jml/100 ml 1,000 106 95 179 230 90 68 115 168 120 *Management of Water Quality and Water Pollution Control Class II, PPRI No.82, 2001 Source: USU

The result of water sampling in the wet season and dry season shows that the present water quality of the

Poring River around the proposed location of the Poring-1 and Poring-2 mini hydropower plants satisfied

all parameters of the national standards. In the same manner, the water quality at the wastewater

discharge points or tributaries also satisfied all parameters of the national standards.

There was no location in which the pipe of domestic wastewater is directly connected to the Poring River

in the section between the proposed Poring-1 Intake Weir and the proposed Poring-2 Powerhouse. There

is only one discharge point of domestic wastewater identified at Site 6 where the public water supply

place is located near a tributary of the Poring River. After conducting the discharge measurement at this

point, 0.018 m3/s of domestic wastewater was poured via the tributary of the Poring River. However, the

domestic wastewater would be diluted with the water from the identified 15 tributaries upstream of Site 6.

Accordingly, it is considered that the impact on water quality would be insignificant.

Consequently, although the discharge of the Poring River decreases significantly during the operation

phase, negative impact from the decrease in water discharge would be insignificant on the water quality

of the Poring River in the section between the Poring-1 Intake Weir and the Poring-2 Powerhouse

because there is almost no source of wastewater discharge into the Poring River.

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Preparatory Survey on North Sumatra Mini 7-47 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(3) Social Environment

1) Scale of impact

In Component 1, two villages with 52 households will be affected. There will be no resettlement;

however, about 22 ha of land will be permanently acquired and about 17.5 ha of land will be temporarily

occupied. As for Component 2, 11 villages with 145 households will be affected. In order to construct

transmission line poles, about 0.4 ha of land will be acquired permanently. The scale of impact of

Component 1 and Component 2 is summarized in Table 7.6.9.

Table 7.6.9 Summary of Affected Area, Households and Assets Component 1: Hydropower Plants

Item Unit Poring-1 Poring-2 Affected Village Number 2 2 Affected Land (Permanently) ha 11.15 11.52 Affected Land (Temporary) ha 8.98 8.56 Affected HHs Number 22 33

Type of Land to be Affected9

Agricultural Land (%) 0 0 Plantation Land (%) 95.58 90.97 Residential Land (%) 0 0.42

Others (%)10 4.42 (bush area, forest, crops, etc.) 8.61 (bush area, forest, crops, etc.)Affected Assets Trees Number 8,682 6,868 Crops except paddy (Permanently)

Number 2,080 1,820

Crops except paddy (Temporary)

Number 0 0

Paddy (Permanently) ha 0.5 0.5 Paddy (Temporary) ha 0 0 Source: Hearing with Acting Village Heads in April 2015 and September 2015 Component 2: Transmission Lines

Item Unit Poring-1 and Poring-2* Affected Village Number 11 Affected Land (Permanently) ha 0.311 Affected HHs Number 145

Type of Land to be Affected State Land (Production Forest Land) (%) 33

Non-state Land (%) 57 Affected Assets11 Land ha 0.31 Tress Number 1,613 Crops (except rice) Number 686 Rice ha 0.035 *The precise project area of the Poring-1 Transmission Line and the Poring-2 Transmission Line will be identified after conducting the detailed measurement survey. Source: Hearing with Acting Village Heads in July 2015

2) Summary of Land Acquisition Plan (LAP)

In compliance with the requirement of the JICA Guidelines, land acquisition plans (LAP) for the Poring-1

9 As aforementioned in Chapter 2.1 (2) (land used by the local community), the project area is categorized as production forest (state land) under the management of the Ministry of Forest. However, it is used by local community. The term “type of land to be affected” means the type of land actually used by the local community. 10 It is difficult to distinguish the area for agriculture, plantation, and others since the land is for multiple uses such as plantation of woods and fruit trees for domestic consumption and/or vegetable garden. Here, agricultural land means paddy; plantation land means the land mainly used for commercial trees; and others means forest land used for domestic consumption. 11 The figure includes the area of state land and non-state land.

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Preparatory Survey on North Sumatra Mini 7-48 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Mini Hydropower Plant, Poring-2 Mini Hydropower Plant, Poring-1 Transmission Line, and Poring-2

Transmission Line were prepared separately.

The following is the summary of the LAP.

a. Policy Gap between the Government of Indonesia and JICA

There is no specific requirement set for land acquisition or resettlement for the private investment Project.

Accordingly, the acquisition or resettlement of the Project will be proceeded in complying with JICA

Guidelines for Environmental and Social considerations and making reference with similar private investment

Projects in Indonesia.

b. Cut-off-date of Eligibility

The cut-off-date of eligibility refers to the date prior to which the occupation or use of the Project area makes

residents/users of the same eligible to be categorized as PAPs and be eligible to Project entitlements. The

cut-off date coincides with the date of the census of affected persons within the Project area boundaries, which

will be conducted at the time of a population census.

In the Project, cut-off-date for titleholders of proposed land is as follows;

- Component 1: Poring 1 and Poring 2 Small Hydropower Plant: 24, April 2015 to 02 May 2015, and 8

September 2015 to 15 September 2015 (Additional survey based on the updated layout: 10 additional

households were identified)

Component 2: Transmission lines for the Poring 1 and Poring 2 Mini Hydropower Plants: Since there is no

boundary of each transmission lines measured, it would be at the time of detailed measurement survey in a

detailed design phase.

c. 4.2 Entitlement Matrix

Based on the hearing from acting village heads in Siantar Naipospos and Pardomuan Nauli as well as the

affected households, an entitlement matrix is developed as shown in Table 7.6.10

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Preparatory Survey on North Sumatra Mini 7-49 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.6.10 Entitlement Matrix

No. Type of Loss Entitled Persons Entitlement Implementation Issues/Guidelines

1. Fixed Assets 1.1 Loss of land for agriculture in the

land for the Project Those who use the land

Cash compensation at replacement cost based on the market price of Project area or price of similar project nearby

Compensation amount is calculated in consulting with and referring market price of Project area or price set for similar project near the project area at detailed measurement survey

1.2 Loss of private structure in the land for the Project

Those who own the structure

Cash compensation based at replacement cost on the current market price of that area

Compensation amount is calculated in consulting with and referring market price of Project area

1.3 Loss of public structure in the land for the Project

Those who own the structure

Rebuild and upgrade the structure

Compensation amount is calculated in consulting with and referring market price of Project area

1.4 Loss of standing crops/tress in the land for constructing the Project

To be assisted as a part of loss of income sources

2 Loss of Income Source 2.1 Loss of income from standing

crops/tress in the land for constructing the Project

Those who cultivating crops/trees

Trees: Cash Compensation based on the rate set by Dept. of Agriculture and Plantation in North Tapanuli Regency Crops: Cash compensation based on the current market price of Project area

Trees: Compensation amount is calculated based on the compensation price list in Department of Agriculture and Plantation in North Tapanuli Regency) at Detailed Measurement Survey Crops: Compensation amount is calculated in consulting with and referring market price of Project area or price set for similar project near the project area at detailed measurement survey

2.2 Loss of income from standing crops/tress in the land which is to be occupied temporary for constructing Project

Those who cultivating crops/trees

Crops: Cash Compensation of one crop season (s) in the occupied period Trees: Cash compensation based on the rate set by Department of Agriculture and Plantation in North Tapanuli Regency

Crops: Compensation amount is calculated in consulting with and referring market price (farm gate price) of Project area at detailed measurement survey Trees: Compensation amount is calculated based on the compensation price list in Department of Agriculture and Plantation in North Tapanuli Regency) at Detailed Measurement Survey

Source: JICA Survey Team

d. Livelihood Restoration Plan

Although there will be no resettlement in the Project, 11.15 ha of land where is used for commercial plantation

as well as vegetable garden for domestic consumption to be used for constructing facilities of the Project.

In addition to provide cash and assistances in order to compensate the loss of income for the PAPs, it is

recommended to provide means for an alternative sustainable livelihood. Taking account of the assistance

requests by PAHs (i.e. infrastructure development for the project affected community, priority employment

etc), skill improvement in the agricultural field would be effective for restoring and improving PAH’s living

standard for long term. Detailed livelihood restoration plan shall be prepared through the livelihood restoration

committee established during detailed design phase.

The livelihood restoration for the PAHs should be continued in an operation phase as well. Accordingly, the

requested assistances from the acting village heads and PAHs, which could not be realized at the time of

construction phase, can be implemented in an operation phase by using the Corporate Social Responsibility

scheme (CSR).

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Preparatory Survey on North Sumatra Mini 7-50 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

7.7 ENVIRONMENTAL MANAGEMENT

7.7.1 INSTITUTIONAL ARRANGEMENT

(1) Pre-construction/Construction Phase

JDG Poring/JDG Cianten will establish the project offices. A staff shall be assigned for implementing the LAP

requirement and environmental monitoring. The roles and responsibilities for each institution concerned in the

pre-construction/construction phase are shown in Table 7.7.1.

Table 7.7.1 Roles and Responsibilities of Institutions Concerned in the Pre-construction /

Construction Phase Institution Roles and Responsibilities Key Parties

Project Office (Poring-1 Mini Hydropower Plant under JDG Poring / Poring-2 Mini Hydropower Plant under JDG Cianten)

- Establish the Environmental and Social Team* - Submit environmental monitoring report to the

Department of Environment, North Tapanuli Regency (every six months) and JICA (every three months)

Project Office

Environmental and Social Team in Poring-1 Mini Hydropower Plant Project Office / Poring-2 Mini Hydropower Plant Project Office)

- Enhance smooth implementation of land acquisition between the project office and PAHs

- Prepare environmental monitoring report

Environmental and Social Team

Environmental and Social Officer in the Construction Contractor Office

- Implement mitigation activities based on the environmental management and monitoring plan

Construction Contractor

Department of Environment, North Tapanuli Regency

- Supervise environmental management activities including land acquisition implemented by the project office

Department of Environment, North Tapanuli Regency

Livelihood Restoration Committee (Grievance Committee)

- Enhance harmonious consensus on compensation and assistances between PAPs/affected community and the project office

- Ensure the implementation of LAP - Act in the Grievance Committee (see Chapter 5

Grievance Redress System)

- Village head (Chair) - All concerned village

authorities - Representatives from PAHs- Representatives of the

project office *Environmental and Social Team is in-charge of LAP implementation as well as UPL-UKL/Environmental Management and Monitoring Source: JICA Survey Team

(2) Operation Phase

The tasks on environmental monitoring will be taken by the Operation and Maintenance Department in

Poring-1 Mini Hydropower Plant (JDG Poring) and Poring-2 Mini Hydropower Plant (JDG Cianten). The

LAP shall be finished by the end of the construction. However, it is highly recommended to give social

considerations to the communities in the project area continuously during the operation phase.

Community development committee which used to be the livelihood restoration committee previously

will be established with the assistance of JDG Poring/JDG Cianten. In consultation with the committee,

JDG Poring will develop a community development plan in the framework of CSR. Details such as

management method shall be finalized at the commencement of the project operation. Proposed roles and

responsibilities of relevant institutions for the CSR activity during the operation phase are shown in Table

7.7.2.

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Preparatory Survey on North Sumatra Mini 7-51 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.7.2 Proposed Roles and Responsibilities for CSR Activity during

the Operation Phase Institution Roles and Responsibilities Key Parties

Poring-1 Mini Hydropower Plant in JDG Poring Poring-2 Mini Hydropower Plant in JDG Cianten

- Establish an Environmental Team - Submit an environmental monitoring

report to the Department of Environment, North Tapanuli Regency every six months

- Develop a plan for CSR and secure budget for the CSR

Poring-1 Mini Hydropower Plant

Environmental and Social Team in Poring-1 Mini Hydropower Plant / Poring-2 Mini Hydropower Plant

- Implement CSR activities Environmental and Social Team

Community Development Committee

- Cooperate with JDG Poring/JDG Cianten for smooth implementation of the CSR

- Village head (Chair) - All concerned village authorities - Representatives from local community - Representatives of Poring-1 Mini

Hydropower Plant Source: JICA Survey Team

7.7.2 MITIGATION MEASURES AND MONITORING PLAN

Based on the result of IEE, mitigation measure and its monitoring plan are developed for each predicted

impact as shown in Table 7.7.3.

Table 7.7.3 Mitigation Measures and Monitoring Plan Mitigation Measures Component 1: Hydropower Plants Pre-construction/Construction Phase Potential Impact

Proposed Mitigation Measures Institutional

ResponsibilityImplementation

Schedule Cost

Anti-Pollution Air Pollution ①Apply preventive maintenance system, optimizing

construction schedule to minimize time that vehicles are in operation.

②Apply dust control measures such as water spraying on the unpaved road.

Contractor During construction

-

Water Pollution ①Apply sediment traps, silt traps, develop fuel handling procedure, and proper sewage

②Monitor the water quality at discharge point of wastewater

Contractor During construction

①Under civil work cost

②Under Environmental Management and Environmental Monitoring Cost

Waste ①Secure sites for disposing of construction wastes,

vegetable debris, and installing garbage bins

Contractor During construction

Under civil work cost

Noise and Vibration

①Limit the construction work only at daytime near the

residential area.

②Apply periodical inspection of the equipment

Contractor During construction

-

Natural Environment Flora, Fauna and Biodiversity

①Instruct all personnel employed by the Contractor not to intrude into the forest land for hunting, trading of wildlife or collecting timber.

Contractor During construction

(instruction can be provided at the time of safety

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Preparatory Survey on North Sumatra Mini 7-52 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

②Prohibit introduction of species by all personnel employed by the Contractor

awareness program)

Topography and Geographical Features

①Avoid unnecessary excavation and digging works Contractor During construction

-

Social Environment Involuntary Resettlement

①Apply appropriate compensation and assistance such as priority employment for the PAHs, community infrastructure improvement for the project affected community

EST* Before commencement of construction activities

Under Environmental Management and Environmental Monitoring Cost

Vulnerable (poor households)

①Apply proper compensation EST Before commencement of construction activities

Indigenous and Ethnic Minority

①Assign a staff who is bilingual in Indonesian and Batak language whenever there is an occasion to communicate with villagers

EST During pre-construction/ construction

Land Use and Utilization of Local Resources

①Apply proper compensation EST Before commencement of construction activities

Landscape ①Avoid leaving borrow pit and cut area

②Reinstate the damage with vegetation coverage

Contractor During construction

Under civil work cost

Water Usage or Water Rights of Common

①Apply appropriate assistance such as priority employment for the PAHs, community infrastructure improvement for the project affected community

EST During pre-construction/ construction

Under civil work cost /Environmental Management and Environmental Monitoring Cost

Communicable Diseases such as HIV/AIDS

①Develop a health awareness program

②Employ local people as much as possible

Contractor During construction

Under Environmental Management and Environmental Monitoring Cost

Working Environment (includes work safety)

①Develop a safety awareness program

②Apply safe working practice

Contractor During construction

Others Accidents ①Prepare road safety measurement plan Contractor During

construction Under Environmental Management and Environmental Monitoring Cost (Included under the cost of working environment)

* EST: Environmental and Social Team at the Project Office of Poring-1 Mini Hydropower Plant/Poring-2 Mini Hydropower Plant Operation Phase (implemented by JDG Poring/JDG Cianten)

Potential Impact Proposed Mitigation Measures

Implementation Schedule

Cost

Natural Environment Flora, Fauna and Biodiversity

①Apply appropriate assistance such as priority employment for the PAHs, community infrastructure improvement for the project affected community

During operation Under the budget of CSR

Hydrological Situation

①Apply appropriate assistance such as priority employment for the PAHs, community infrastructure improvement for the project affected community

During operation

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Preparatory Survey on North Sumatra Mini 7-53 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Social Environment Land Use and Utilization of Local Resources

①Apply appropriate assistance such as priority employment for the PAHs, community infrastructure improvement for the project affected community

During operation Under the budget of CSR

Water Usage or Water Rights of Common

①Apply appropriate assistance such as priority employment for

the PAHs, community infrastructure improvement for the project affected community

During operation

Others Accidents ①Apply warning signs along the headrace channel During operation Under operation

and maintenance cost

Component 2: Transmission Lines Pre-construction/Construction Phase Potential Impact Proposed Mitigation Measures Institutional

ResponsibilityImplementation

Schedule Cost

Anti-Pollution Air Pollution ①Apply preventive maintenance system, optimizing

construction schedule to minimize time that vehicles are in operation.

②Apply dust control measures such as water spraying on the unpaved load.

Contractor During construction

-

Water Pollution ①Apply sediment traps and silt traps, develop fuel handling procedure, and proper sewage

②Monitor the water quality at discharge point of wastewater

Contractor During construction

①Under civil work cost

②Under Environmental Management and Environmental Monitoring Cost

Waste ①Secure sites for disposing of construction wastes,

vegetable debris, and installing garbage bins

Contractor During construction

Under civil work cost

Noise and Vibration

①Limit the construction work only at daytime near the residential area.

②Apply periodical inspection of the equipment.

Contractor During construction

-

Natural Environment Flora, Fauna and Biodiversity

①Instruct all personnel employed by the Contractor not to intrude into the forest land for hunting, trading of wildlife or collecting timber.

②Prohibit species introduction by all personnel

employed by the Contractor

Contractor During construction

(instruction can be provided at the time of safety awareness program)

Topography and Geographical Features

①Avoid unnecessary excavation and digging works Contractor During construction

-

Social Environment Involuntary Resettlement

①Apply appropriate compensation and assistances such as priority employment for the PAHs, community infrastructure improvement for the project affected community

EST Before commencement of construction

Under Environmental Management and Environmental Monitoring Cost

Vulnerable (poor households)

①Apply proper compensation EST Before commencement of construction

Indigenous and Ethnic Minority

①Assign a staff who is bilingual in Indonesian and Batak language whenever there is an occasion to communicate with the villagers

EST During pre-construction/ construction

Land Use and Utilization of Local Resource

①Apply proper compensation EST Before commencement of construction

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Landscape ①Avoid leaving borrow pit and cut area

②Reinstate the damage with vegetation coverage

Contractor During construction

Under civil work cost

Communicable Diseases such as HIV/AIDS

①Develop a health awareness program

②Employ local people as much as possible

Contractor During construction

Under Environmental Management and Environmental Monitoring Cost

Working Environment (includes work safety)

①Develop a safety awareness program

②Apply safe working practice

Contractor During construction

Accidents ①Prepare road safety measurement plan Contractor During construction

Under Environmental Management and Environmental Monitoring Cost (Included under the cost of working environment)

* EST: Environmental and Social Team at the Project Office of Poring-1 Mini Hydropower Plant/Poring-2 Mini Hydropower Plant Operation Phase (implemented by JDG Poring/JDG Cianten)

Potential Impact Proposed Mitigation Measures Implementation Schedule Cost Soil Contamination ①Develop operation and maintenance program During operation Under operation and

maintenance cost Monitoring Plan Component 1: Hydropower Plants Pre-construction/Construction Phase

Potential Impact Parameter to be Monitored

Measurement and Frequency

Institutional Responsibility

Implementation Schedule

Cost

Anti-Pollution Air Pollution ①Vehicle Inspection Checklist

②Site Inspection (Construction Site)

①Daily, Visual Inspection

②Daily during Dry Season

EST* During construction

Under Environmental Management and Environmental Monitoring Cost

Water Pollution ①Site Inspection (Construction Site and Worker’s Camp)

②Review the Result of Water Sampling (Construction Site and Worker’s Camp)

①Monthly

②Monthly

EST During construction

Waste ①Site Inspection (Construction Site and Worker’s Camp)

①Monthly EST During construction

Noise and Vibration

①②Site Inspection

(Construction Site)

①②Monthly EST During construction

Natural Environment Flora, Fauna and Biodiversity

①②Site Inspection

(Construction Site and Worker’s Camp)

①②Monthly EST During construction

Under Environmental Management and Environmental Monitoring CostTopography and

Geographical Features

①Site Inspection (Construction Site)

①Monthly EST During construction

Social Environment Involuntary Resettlement

①Site Inspection

(Construction Site)

①Monthly (weekly

during disbursement of compensation)

EST Before commencement of construction activities

Under Environmental Management and Environmental Monitoring CostVulnerable (poor

households) ①Site Inspection ①Monthly EST Before

commencement

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Preparatory Survey on North Sumatra Mini 7-55 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

(Construction Site) (weekly during disbursement of compensation)

of construction activities

Indigenous and Ethnic Minority

①Site Inspection (Construction Site)

①Monthly EST During pre-construction/ construction

Land Use and Utilization of Local Resources

①Site Inspection (Construction Site)

①Monthly EST Before commencement of construction activities

Landscape ①②Site Inspection (Construction Site)

①②Monthly EST During construction

Water Usage or Water Rights of Common

①Site Inspection (Construction Site)

①Monthly (weekly during disbursement of compensation)

EST During pre-construction/ construction

Communicable Diseases such as HIV/AIDS

①Number of Trainings

②Site Inspection (Construction Site)

①Every six months

②Every six months

EST During construction

Working Environment (includes work safety)

①Number of Trainings

②Site Inspection

(Construction Site)

①Every six months

②Monthly

EST During construction

Others Accident ①Number of Trainings ①Every six months EST During

construction Under Environmental Management and Environmental Monitoring Cost

* EST: Environmental and Social Team at the Project Office of Poring-1 Mini Hydropower Plant/Poring-2 Mini Hydropower Plant Operation Phase (implemented by JDG Poring/JDG Cianten) Potential Impact

Parameter to be MonitoredMeasurement and Frequency Implementation

Schedule Cost

Natural Environment Flora, Fauna and Biodiversity

①Check annual CSR plan developed by JDG Poring/JDG Cianten

①Annually During operation Under the budget of CSR

Hydrological Situation

①Check annual CSR plan

developed by JDG Poring/JDG Cianten

①Annually During operation

Social Environment Land Use and Utilization of Local Resources

①Check annual CSR plan developed by JDG Poring/JDG Cianten

①Annually During operation Under the budget of CSR

Water Usage or Water Rights of Common

①Check annual CSR plan

developed by JDG Poring/JDG Cianten

①Annually During operation

Others Accidents ①Site Inspection ①Every 6 Months During operation Under operation

and maintenance cost

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Preparatory Survey on North Sumatra Mini 7-56 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Component 2: Transmission Lines Pre-construction/Construction Phase Potential Impact

Parameter to be Monitored Measurement and Frequency

Institutional Responsibility

Implementation Schedule

Cost

Anti-Pollution Air Pollution ①Vehicle Inspection Checklist

②Site Inspection (Construction

Site)

①Daily, Visual Inspection

②Daily during Dry Season

EST* During construction

Under Environmental Management and Environmental Monitoring Cost

Water Pollution ①Site Inspection (Construction Site and Worker’s Camp)

①Monthly EST During construction

Waste ①Site Inspection (Construction

Site and Worker’s Camp)

①Monthly EST During construction

Noise and Vibration

①②Site Inspection

(Construction Site)

①②Monthly EST During construction

Natural Environment Flora, Fauna and Biodiversity

①②Site Inspection

(Construction Site and Worker’s Camp)

①②Monthly EST During construction

Under Environmental Management and Environmental Monitoring CostTopography

and Geographical Features

①Site Inspection (Construction Site)

①Monthly EST During construction

Social Environment Involuntary Resettlement

①Site Inspection (Construction Site)

①Monthly (weekly during disbursement of compensation)

EST Before commencement of construction

Under Environmental Management and Environmental Monitoring Cost

Vulnerable (poor households)

①Site Inspection (Construction Site)

①Monthly (weekly during disbursement of compensation)

EST Before commencement of construction

Indigenous and Ethnic Minority

①Site Inspection (Construction Site)

①Monthly EST During pre-construction/ construction

Land Use and Utilization of Local Resources

①Site Inspection (Construction Site)

①Monthly EST Before commencement of construction

Landscape ①②Site Inspection (Construction Site)

①②Monthly EST During construction

Communicable Diseases such as HIV/AIDS

①Number of Trainings

②Site Inspection (Construction

Site)

①Every six months

②Monthly

EST During construction

Working Environment (includes work safety)

①Number of Trainings

②Site Inspection (Construction Site)

①Every six months

②Monthly

EST During construction

Others Accidents ①Number of Trainings ①Every six months EST During

construction Under Environmental Management and Environmental Monitoring Cost

* EST: Environmental and Social Team at the Project Office of Poring-1 Mini Hydropower Plant/Poring-2 Mini Hydropower Plant

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Preparatory Survey on North Sumatra Mini 7-57 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Operation Phase (implemented by JDG Poring/JDG Cianten) Potential Impact

Parameter to be Monitored Measurement and

Frequency Implementation Schedule Cost

Pollution Control Soil Contamination

①Site Inspection ①Daily During operation Under operation and maintenance cost

Source: JICA Survey Team

7.7.3 IMPLEMENTATION SCHEDULE

(1) Pre-construction Phase

1) Establishment of Livelihood Restoration Committee

A livelihood restoration committee shall be established in order to deal with issues such as compensation

and assistance. It will enhance harmonious consensus on compensation and assistance between the

project-affected persons (PAPs)/affected community and the project office.

The livelihood restoration committee will act as grievance redress committee as well. Any complaints

from the affected community and PAPs related to the construction and construction activities of the

Poring-1 Mini Hydropower Plant shall be dealt in the committee.

2) Detailed Measurement Survey (DMS)

After obtaining IPPKH (Forest Area Usage License), a DMS must be undertaken in order to a) finalize

the affected land and its users (PAPs) and b) finalize the affected structure and its owner in collaboration

with PAPS and local authorities.

3) Socialization to Finalize Compensation and Assistance

After confirming the affected land and its users, entitlement of compensation and assistance to PAPs and

affected community shall be finalized by conducing socialization through livelihood restoration

committee and consultation with PAPs. It is necessary to have the opportunity of socialization and

consultation as many times as possible for achieving consensus among stakeholders.

4) Finalization of the Draft LAP

With the outcome of the DMS, accurate scope of impacts (name and quantities of affected assets) will be

identified and detailed compensation rates and rehabilitation measures will be prepared. With the

information incorporated, the draft LAP shall be finalized.

5) Signing of Compensation Contracts and Payment of Compensation to PAPs

The final step in the land acquisition implementation process is the signing of compensation contracts and

delivery of payments to PAPs. This step should be completed prior to the commencement of construction

activities.

(2) Construction Phase

Most of the tasks in the LAP will be completed during the pre-construction phase. When conducting

monitoring activities based on IEE during the construction phase, AHHs who need any support resulting

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Preparatory Survey on North Sumatra Mini 7-58 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

from the land acquisition will be assisted.

(3) Operation Phase

Environmental monitoring activities will be undertaken by the operation and maintenance department

under Poring-1 Mini Hydropower Plant/Poring-2 Mini Hydropower Plant. The LAP shall end at the

completion of construction. Activity on social considerations will be implemented continuously under the

scheme of CSR.

Implementation schedule is summarized in Figure 7.7.1.

- Component 1: Hydropower Plants

- Component 2: Transmission Lines

Source: JICA Survey Team

Figure 7.7.1 Implementation Schedule

10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4

Establish Livelihood RestorationCommittee (Grievance Redress ▼Detailed Measurement Survey

Socialization on finalize compensationand assistance

Finalize Land Acquisiiton Plan

Compensation and Land Acquisition

Environmental Monitoring by EST

Enviornmental Monitoirng by Operation andMaintenance Department(CSR Activities by EST)

Operation Phase

2019

Construction Phase

Pre-Construction Phase

Year (per calendar year)2015 2017 20182016

Road Upgrade (5months) Main Works (22

10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4

Establish Livelihood Restoration Committee(Grievance Redress Committee) ▼Detailed Measurement Survey

Socialization on finalize compensation andassistance

Finalize Land Acquisition Plan

Compensation and Land Acquisition

Environmental Monitoring by EST

Environmental Monitoring by Operationand Maintenance Department(CSR Activities by EST)

Operation Phase

2019

Construction Phase

Pre-Construction Phase

Year (per calendar year)2015 2017 20182016

Main Works (22 months)

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Preparatory Survey on North Sumatra Mini 7-59 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

7.8 STAKEHOLDER MEETING

Throughout the IEE process, formal and informal consultations were undertaken with key stakeholders,

including central and local government officials and persons and communities in the project area. The

primary objective of the stakeholder consultation is to provide information on the project such as purpose

of the project, layout of the project, schedule and method of construction and the likely environmental

and social impacts of the project construction and operation. In addition, environmental and social

information on the project area throughout the meetings and public concerns about the project are to be

collected. In particular, since the project will entail land acquisition, a series of public consultation

meeting (PCM) has been conducted for PHS in the project area.

The summary of focused group meeting on fish and fishery is shown in Table 7.8.1. The outcomes of the

PCM are shown in Table 7.8.2. Information obtained from administrative bodies as well as opinions

collected from the individual and public consultation meetings are reflected on the LAP development

process.

Table 7.8.1 Summary of Focused Group Meeting No Requested Assistance for Community Development Responses

1 Enhance rural development for the progress of villager’s living standards

Community infrastructure will be improved as a part of assistance

2 Give the priority for local people to be a worker of this project in the construction and operational phases

Local people, in particular PAHs will be prioritized to be employed as much as possible in a construction and operation phase

2 Improve the domestic water supply for villagers in two affected village, and improving the condition of public bathing and public toilet.

Improving domestic water supply and public bating and public toilet will be one of the option for community infrastructure improvement

3 Improve the infrastructure such as improvement of public road, bridges (between Limus sub-village in Siantar Naipospos Village and electrification

Improvement of public road will be realized as a part of project.

4 Improve crop yields of frankincense/benzoin Providing skill improvement as a part of livelihood restoration plan for the PAHs

Opinion (comment, recommendation etc)

1

This project help this village to make improvement for social and public facilities and make it equal for each sub village, it is better to avoid social jealousy among villagers who lives in each sub village in the village.

Information on the project will be disseminated transparently

2 Make some training for housewives in order to make economic business to assist the economic life of the family

Providing skill improvement as a part of livelihood restoration plan for the PAHs

3 Start this project as soon as possible and not make survey only.

After obtaining financial assurance, the project will be realized ASAP

4 This project is the positive impact for this village. -

5 If there is affected agricultural land for this project, it has to be fair for compensation process.

Information on the project will be disseminated transparently

6 Help for the procurement of additional teachers to school in our village

It will be considered as a one of option for the affected community development in an operation phase

Source: JICA Survey Team

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Preparatory Survey on North Sumatra Mini 7-60 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Table 7.8.2 Summary of Public Consultation Meetings Date Location Target No. of Attendees Remarks/Requests Responses 17 Sept. 2015 Time 9:00-11:30

Office Hall in Carmat Tarutung Office

Officials -Tatutun Subdistrict -Villages --Hutatorian Vlll --Aek Sian Simun - -Hutatoruan lll - -Parbubu 1 - -Hutatoruan 1, -PAHs

- 71 participants:

- 48 PAHs - 7 Villagers - 16 Officials

- PAHs agreed and supported these projects, they requested information about the compensation on land and plants/agriculture.

- The company must think about the

safety of the people around the transmission lines.

- Precise identification of PAHs will be needed for the final database of affected land and plants/agriculture

- Compensation process will be implemented by using “pago-pago (compensation to be set in the negotiation in the Toba Batak)”

- Price of compensation will be based on the market price of the land. The price of plants from government is just a basis for negotiation and it will be finalized through the negotiation.

- Compensation given to PAHs will be either by cash or bank transfer.

- Priority of employment at the site has to be given to the local people in the project area, especially for the member of PAHs whose age is older than 16 years olds (the age after finishing compulsory education)

- CSR activities will be provided to the villages according to the capability of the company

- Safety measures at construction

sites will be duly applied

18 Sept. 2015 Time 11:00 – 13:30

HKBP Church in Lobu Haminjon Subvillage (Siantar Naipospos Village)

Officials - Adian Koting Subdistrict - Villages -- Siantar Naipospos

- 64 participants for Poring-1 and Poring-2 Mini Hydropower Plants:

- 31 PAHs - 28 Villagers- 5 Officials

- 15 PAHs for transmission lines

- Support these projects as long as these projects do not make people worse off.

- This project has to give priority to the villagers as workers, especially for the PAHs.

- This project has to give advantage to the villagers in Siantar Naipospos Village.

- Worry if the headrace is near the settlement area.

- Villagers in Siantar Naipospos are

asking for electrification because they do not have electricity until today.

- Compensation processes need to be transparent and directly negotiate to the project owner on land and plant/agriculture.

- The final survey for PAHs has to be very detailed.

- If the company needs a partner for

business, the company has to give priority to local entrepreneurship

- Priority of employment at the site has to be given to the local people in the project area, especially for the member of PAHs whose age is older than 16 years olds (the age after finishing compulsory education)

- Layout of the headrace near the settlement area will designed dully considering the safety of settlement area

- Electrification will be difficult since it need approval from PLN, however, infrastructure in the affected community will be improved by the project

- This project can help improve some infrastructure by CSR program in an operation phase as well

- Compensation process will be implemented by using “pago-pago (compensation to be set in the negotiation in the Toba Batak)”

- Detailed measurement survey will be conducted in further phase (detailed desing phase)

- Priority of employment at the site

has to be given to the local people in the project area, especially for

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Preparatory Survey on North Sumatra Mini 7-61 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Date Location Target No. of Attendees Remarks/Requests Responses first.

- Anticipate any negative impact to the community and increase its positive impact.

the member of PAHs whose age is older than 16 years olds (the age after finishing compulsory education)

18 Sept. 2013 Time 14:00 – 16:30

HKBP Church in Torhonas Subvillage (Pardomuan Nauli Village)

Officials - Adian Koting Subdistrict -- Pardomuan Nauli

- 6 participants for Poring-1 and Poring-2 Mini Hydropower Plants: All of them are PAHs.

- 78 participants for transmission line:

- 55 PAHs - 17 Villagers- 6 Officials

- Support this project to be started as soon as possible.

- The land is an inheritance from one

generation to another, but no land certificate is available. They asked this situation to the project owner.

- This project should give priority to

local labor from the village if the development activities are in this village.

- Compensation processes have to

involve the PAHs and negotiate directly to the project owner on the land and plant/agriculture, and no fees for the PAHs.

- After the measurement, if the land

owned by the community is left with very little area, then the public suggested that the company has to buy it wholly because it would not be beneficial for them to use it for agriculture if the remaining land is very small.

- The company has to improve some

infrastructure and developed the village by CSR program.

- If the status of the land is a

production forest (government land) or limited production forest (government land), the company has to pay the government for rental fee, and the local people who cultivated the land for compensation. The compensation rate will be set through the “pago-pago” processes.

- Priority of employment at the site has to be given to the local people in the project area, especially for the member of PAHs whose age is older than 16 years olds (the age after finishing compulsory education)

- Compensation process will be implemented by using “pago-pago (compensation to be set in the negotiation in the Toba Batak)”

- During the estimation of the compensation, this issue will be take for granted

- Affected community infrastructure will be improved as a part of assistance for affected community in a construction phase as well as operation phase by CSR program

19 Sept 2015 Time 11:00- 13:30

HKBP Church in Pansurbatu Village

Officials - Adian Koting Subdistrict Villages -- Pansurbatu -- Pansurbatu 2

56 participants: - 30 PAHs - 19 Villagers - 7 Officials

- Participants asked about the status of the land (government land) since there are no land certificates.

- There are some worries if they will

agree to give their land to this company; the company that will manage the land in the future is a mine company and not for micro power plants.

- Participants asked for a transparent

compensation process, and to directly negotiate with the project owner on land and plant/agriculture.

- Identification of PAHs should be made for the final compensation process and there are no fees or cutting the number of payments; they asked to directly give the money to the PAHs by cash or bank transfer.

- The company will not make people lose their rights for .using the land (government land)

- The land will be used only for mini hydropower plant

- Compensation process will be

implemented by using “pago-pago (compensation to be set in the negotiation in the Toba Batak)”

- Identification of PAHs will be finalized in conducting detailed measurement survey in a further phase and there will be no fee to be asked for. The compensation money will be paid by cash or bank transfer.

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Preparatory Survey on North Sumatra Mini 7-62 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

Date Location Target No. of Attendees Remarks/Requests Responses

- Safety of transmission line was asked.

- Participants demanded honesty regarding the negative and positive effects of the project, as well as honesty in the compensation process.

- There are no negative impacts for

people if they work under the transmission lines, because it is 33 kV. (low voltage)

- Information on the project will be disseminated transparently

Pending - Siatal Barita Subdistrict Villages -Siraja Hutagalung - Simorangkir Julu

- After obtaining the official letter from Bupati (North Tapanuli District Office), PCM has to be organized.

Source: JICA Survey Team

7.9 ESTIMATION OF REDUCTION OF GREENHOUSE GAS

Hydropower generation utilizes hydraulics potential energy for power generation without producing

greenhouse gas (GHG) and is considered as renewable energy. Development and introduction of a new

hydropower station into the power system which includes thermal power generation using fossil fuels can

directly contribute to reduce the GHG emission reduction. In this analysis, GHG reduction by Poring-1

and Poring-2 mini hydropower development is estimated.

The method to estimate the GHG reduction is introduced in “Methodological Tool: Tool to calculate the

emission factor for an electricity system” prepared within the framework convention on climate change

by the United Nations. The method is adopted as the method to calculate the GHG emission reduction for

clean development mechanism also known as CDM.

According to the method, the GHG emission reduction by a hydropower plant is calculated by the

following equation:

ERy = BEy – PEy - LEy

BEy = EGBL,y * EF CO2, grid, y

Where, ERy : GHG emission reduction in year y (t CO2/year)

BEy : GHG emission by substituted power plant in year y (Baseline emission) (t CO2)

PEy : GHG emission by the hydropower plant in year y (t CO2)

LEy : Leakage GHG emission of the hydropower plant in year y (t CO2）

EGBL,y : Annual electrical energy supplied to the grid by the hydropower plant (MWh)

EF CO2, grid, y : Combined margin grid emission factor in year y (t CO2/MWh)

The emission factor is obtained by the weighted average of build margin and operation margin. The

Indonesian National Commission on CDM released the grid emission factor of Sumatra Island until year

2012, and the value is 0.686 (t CO2/MWh). The leakage GHG and GHG emission by the hydropower

plant is negligibly small, and therefore assumed to be zero.

The annual electrical energy productions of Poring-1 and Poring-2 mini hydropower stations are 69.1

GWh/year and 75.3 GWh/year, respectively. Total loss of energy from the power plant to the receiving

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Preparatory Survey on North Sumatra Mini 7-63 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

point of Tarutung Substation is estimated at 13.7%. Therefore, the annual power generation amounts

supplied to the grid by Poring-1 and Poring -2 mini hydropower stations are estimated to be 59.6

GWh/year and 65.0 GWh/year, respectively. Accordingly, the GHG emission reduction for the above

annual power generation is estimated as follows:

Poring-1 Mini Hydropower Station : 40,885.6 t CO2/year

Poring-2 Mini Hydropower Station : 44,590.0 t CO2/year

7.10 CONCLUSIONS AND RECOMMENDATIONS

7.10.1 CONCLUSIONS

After conducting the IEE by examining the available data, hearing with stakeholders, carrying out site

reconnaissance, conducting site survey and laboratory analysis, it is concluded that no significant negative

impact was predicted and the predicted impacts could be avoided or minimized by applying

countermeasures.

As for Component 1 (Hydropower Plants), the main negative impacts will be temporary and site-specific

pollution such as air pollution, water pollution, waste generation, and noise and vibration due to

construction activities during the construction phase. In addition, fish resources and fishery will be

affected due to the diversion of water from the Poring River to the headrace channels for about 5 km

section from the Poring-1 Intake Weir to the Poring-2 Powerhouse during the operation phase.

Similar to Component 1, the main negative impacts of Component 2 (Transmission Lines) will be

temporary and site-specific pollution such as air pollution, water pollution, waste generation, and noise

and vibration due to construction activities during the construction phase.

Effort was made to avoid any resettlement due to the construction of the project facilities for both

Component 1 and Component 2. Consequently, there will be no resettlement resulting from constructing

the project facilities.

7.10.2 RECOMMENDATIONS

The following are the procedures to be taken in the further project phases:

Obtain approval for UKL-UPL: The UKL-UPL on transmission lines of Poring-1 and Poring-2

which is now under review at Bupati needs to be approved.

Organize public consultation meeting (PCM): The PCM at Siatal Barita Subdistrict is now pending.

After obtaining an official letter from Bupati (North Tabanuli District Office), the PCM shall be

organized to explain the result of IEE as well as the LAP to affected community and PAPs.

Establish a livelihood restoration committee: A livelihood restoration committee shall be established

in the affected community in order to deal with issues such as compensation and assistances.

Finalize the land acquisition plan (LAP): The information on the affected land and its users and

affected structure and its users identified after DMS shall be incorporated into the draft LAP for

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Preparatory Survey on North Sumatra Mini 7-64 Nippon Koei Co., Ltd. Hydropower Project (PPP Infrastructure Project)

finalization.

Organize socialization: It is necessary to have opportunity of socialization and consultation as many

times as possible for achieving consensus among stakeholders on compensation, assistances or any

issues related to the construction before the construction phase.

Enhance community development: It is recommended that social considerations will be continuously

given to the affected community during the operation phase by using the CSR scheme.