123
ENVIRONMENTAL ASSESSMENT FOR REHABILITATION OF PIMBURATHTHEWA DAM DAM SAFETY AND WATER RESOURCES PLANNING PROJECT DSWRPP-AF/CS/QCBS/03-02 FINAL REPORT OCTOBER 2015 MG CONSULTANTS (PVT) LTD

MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

Embed Size (px)

Citation preview

Page 1: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

ENVIRONMENTAL ASSESSMENT FOR REHABILITATION OF

PIMBURATHTHEWA DAM

DAM SAFETY AND WATER RESOURCES PLANNING PROJECT

DSWRPP-AF/CS/QCBS/03-02

FINAL REPORT

OCTOBER 2015

MG CONSULTANTS (PVT) LTD

Page 2: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

i | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

TABLE OF CONTENTS

LIST OF FIGURES ........................................................................................................................... v

LIST OF TABLES .......................................................................................................................... vii

ABREVIATIONS .......................................................................................................................... viii

TEAM OF CONSULTANTS FOR EA STUDY ....................................................................................... x

1. INTRODUCTION ........................................................................................................................ 1

1.1 PROJECT DESCRIPTION AND JUSTIFICATION ......................................................................... 1

1.1.1 Background of the Project ..................................................................................................... 1

1.1.2 Project Location ..................................................................................................................... 4

1.2 SCOPE OF THE PROJECT AND ENVIRONMENTAL ASSESSMENT .............................................. 9

1.2.1 Scope of the Project ............................................................................................................... 9

1.2.2 Environmental Assessment Requirements ............................................................................ 9

1.3 OBJECTIVES OF THE STUDY ................................................................................................ 10

1.4 METHODOLOGY ................................................................................................................ 11

1.4.1 Mobilization ......................................................................................................................... 11

1.4.2 Scoping Meetings and Reconnaissance Visits ...................................................................... 11

1.4.3 Data and Information Collection .......................................................................................... 12

1.4.4 Baseline Surveys ................................................................................................................... 12

1.4.5 Identification and assessment of impacts, nature and magnitude ..................................... 13

1.4.6 Institutional Arrangements .................................................................................................. 13

1.4.7 Environmental Impact Analysis, Proposed Mitigatory Strategies and preparation of the

Environmental Management Plan (EMP) ..................................................................................... 14

1.4.8 Preparation of the Environmental Monitoring Plan (EoMP) ............................................... 15

1.4.9 Preparation of the cost estimate for implementation of the EMP and EMoP .................... 16

Page 3: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

ii | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.4.10 Recommendations and Conclusions .................................................................................. 16

1.4.11 Documentation Procedure ................................................................................................ 16

1.5 EXPECTED OUTCOMES OF THE REPORT .............................................................................. 19

1.6 WORK PLAN ...................................................................................................................... 20

2. DESCRIPTION OF THE EXISTING ENVIRONMENT ...................................................................... 22

2.1 OVERVIEW ........................................................................................................................ 22

2.2 PHYSICAL ENVIRONMENT .................................................................................................. 22

2.3 BIOLOGICAL ENVIRONMENT WITH FLORA AND FAUNA ...................................................... 34

2.3.1 Existing Habitats and ecological significance ....................................................................... 34

2.3.2 Flora ..................................................................................................................................... 34

2.3.3 Invasive Species ................................................................................................................... 35

2.3.4 Fauna .................................................................................................................................... 35

2.3.5 Rare, Threatened and Endemic Flora and Fauna ................................................................. 35

2.3.6 Migratory Paths.................................................................................................................... 36

2.3.7 Proposed borrow area ......................................................................................................... 36

2.4 SOCIOECONOMIC ENVIRONMENT ..................................................................................... 37

2.4.1 Local Administrative Units in the Project Area .................................................................... 37

2.4.2 Land Use in Different Areas of the Irrigation Schemes ........................................................ 39

2.4.3 Demographic Data Relevant to the Project Area ................................................................. 39

2.4.4 Economic Activities of Project Related Population .............................................................. 40

2.5 OTHER WATER USES .......................................................................................................... 41

2.6 CURRENT ENVIRONMENTAL ISSUES OF THE PROJECT AREA ................................................ 42

2.6.1 Physical Issues ...................................................................................................................... 42

Page 4: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

iii | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

2.6.2 Ecological Issues ................................................................................................................... 42

2.6.3 Socioeconomic Issues .......................................................................................................... 42

3. PROPOSED INTERVENTIONS ................................................................................................... 44

3.1 PROPOSED ENGINEERING INTERVENTIONS ........................................................................ 44

3.1.1 Resource and Material Requirements for Proposed Interventions of Pimburaththewa

Reservoir ....................................................................................................................................... 49

3.2 PROPOSED BORROWING ACTIVITIES AND IDENTIFIED BORROW SITES ................................ 54

3.2.1 Turfing Materials .................................................................................................................. 54

3.2.2 Earth ..................................................................................................................................... 54

3.2.3 Metal .................................................................................................................................... 54

3.2.4 Sand ...................................................................................................................................... 54

3.2.5 Gravel ................................................................................................................................... 54

3.3 PROPOSED INTERVENTIONS THAT COULD AFFECT NEIGHBORING COMMUNITIES ............... 54

3.4 PROPOSED INTERVENTIONS THAT COULD AFFECT THE NATURAL HABITATS ........................ 55

4. PROJECT INDUCED IMPACTS ................................................................................................... 56

4.1 IDENTIFICATION OF PROJECT INDUCED IMPACTS ............................................................... 56

4.2 QUANTIFICATION OF THEIR SIGNIFICANCE ......................................................................... 67

5. ENVIRONMENTAL MANAGEMENT PLAN ................................................................................. 68

5.1 GENERAL OVERVIEW ......................................................................................................... 68

5.2 IDENTIFICATION OF IMPACTS AND THEIR MITIGATIONS ..................................................... 68

5.3 PROCUREMENT OF MATERIAL NEEDED FOR IMPLEMENTING THE PROPOSED INTERVENTIONS

.............................................................................................................................................. 88

5.3.1 Material Sourcing ................................................................................................................. 88

5.3.2 Management of Borrow Sites .............................................................................................. 88

Page 5: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

iv | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5.3.3 Quarry Operations and Management of Quarry Sites ......................................................... 89

5.4 SAFETY ISSUES .................................................................................................................. 89

5.5 OPERATION OF LABOUR CAMPS ........................................................................................ 90

5.6 IMPLEMENTATION PROCEDURES OF PROPOSED MITIGATION ............................................ 91

5.7 INFORMATION DISCLOSURE AMONG STAKEHOLDERS ........................................................ 92

5.8 POST-CONSTRUCTION ACTIVITIES ...................................................................................... 92

5.9 FORMAL CLEARANCES AND APPROVAL NEEDED................................................................. 93

5.10 PROCEDURES FOR DEALING WITH CHANCE FINDS ............................................................ 94

5.10.1 Chance found Flora and Fauna .......................................................................................... 94

5.10.2 Chance found Archaeological Property ............................................................................. 94

6. MONITORING PLAN ................................................................................................................ 95

6.1 ENVIRONMENTAL COMPLIANCE AND MONITORING .......................................................... 95

7. COST ESTIMATION FOR ENVIRONMENTAL MANAGEMENT PLAN ............................................. 98

7.1 COST ESTIMATE OF ENVIRONMENTAL MANAGEMENT PLAN .............................................. 98

8. CONCLUSIONS AND RECOMMENDATIONS ............................................................................ 101

8.1 CONCLUSIONS ................................................................................................................. 101

8.2 RECOMMENDATIONS ...................................................................................................... 102

ANNEXURES ............................................................................................................................. 104

ANNEX 1: DETAILS OF THE FARMING COMMUNITY ................................................................ 104

ANNEX 2: DETAILS OF THE COST BENEFIT OF AN ACRE OF PADDY LAND IN PIMBURATTEWA .. 105

ANNEX 3: LOCATION MAP FOR THE IDENTIFIED QUARRY AND BORROW SITES FOR

PIMBURATHTHEWA TANK .................................................................................................... 106

ANNEX 4: FAUNA RECORDED FROM PIMBURATTEWA SITES................................................... 107

ANNEX 5: PHOTOGRAPHS – SOCIO ECONOMIC SURVEY ......................................................... 112

Page 6: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

v | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

LIST OF FIGURES

Figure 1.1: The seven reservoirs focused for the present cluster under the DSWRPP .......................... 3

Figure 1.2: Location map of the Pimburaththewa Dam (Close-up view from Topo sheet) ................... 5

Figure 1.3: Map of System B. Pimburaththewa is fed directly by the Maduru Oya LB main canal.

Pimburaththewa Reservoir is highlighted............................................................................................... 6

Figure 1.4: Location Map of Pimburaththewa Reservoir ........................................................................ 7

Figure 1.5: Land use of the area where Pimburaththewa Reservoir is located ...................................... 8

Figure 1.6: Proposed Approach and Methodology for the Study ......................................................... 18

Figure 2.1: Monthly average, high and low temperature in Aralaganvila near Pimburaththewa tank

area ....................................................................................................................................................... 23

Figure 2.2: Monthly average rainfall in Aralaganvila near Pimburaththewa tank area........................ 24

Figure 2.3: Topography of the Area (Note: Pimburaththewa and Maduru Oya (South of

Pimburaththewa) are both located below the 100 m contour line) .................................................... 26

Figure 2.4: Distribution of Soil Groups (Panabokke, 1975) ................................................................... 28

Figure 2.5: The catchment areas of the Reservoirs/Tanks considered for the present EA ................. 30

Figure 2.6: The satellite view of the catchment areas of the Reservoirs/Tanks considered for the

present EA ............................................................................................................................................. 31

Figure 2.7: Main Pimburaththewa Catchment ..................................................................................... 32

Figure 2.8: Pimburaththawa spill .......................................................................................................... 36

Figure 2.9: Rubble storage site ............................................................................................................. 37

Figure 3.1: Damages to the Spillway ..................................................................................................... 47

Figure 3.2: Erosion in spillway side ways .............................................................................................. 47

Figure 3.3: Damaged Spillway ............................................................................................................... 47

Figure 3.4. Spill tail areas collapsed completely ................................................................................... 47

Page 7: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

vi | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 3.5: Damaged spillway ............................................................................................................... 47

Figure 3.6: Damaged Spillway ............................................................................................................... 47

Figure 3.7: Completely eroded parts of the Spillway ............................................................................ 48

Figure 3.8: Completely eroded parts of the Spillway ............................................................................ 48

Figure 3.9: Removal of shrubs needed on the rip rap rip rap in some areas ....................................... 48

Figure 3.10: Riprap damaged at some places ....................................................................................... 48

Figure 3.11: Seepages at D/S areas ....................................................................................................... 48

Figure 3.12: Seepage at D/S areas ........................................................................................................ 48

Page 8: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

vii | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

LIST OF TABLES

Table 1.1: Data that need to be collected during the detailed study ................................................... 13

Table 1.2: Work plan for the proposed environmental study .............................................................. 20

Table 1.3: Tasks assigned to each team member and the responsibility ............................................. 21

Table 2.1: Summary of the fauna recorded in the rubble storage site and Pimburaththewa spillway site

.............................................................................................................................................................. 35

Table 2.2: Details of the local administrative units related to the project area ................................... 38

Table 2.3: Details of Project Relevant Population ............................................................................... 39

Table 2.4: Distribution of income generation activities among families in project related villages .... 40

Table 2.5: Details Expressed by the Farmer Leaders/Block Officers .................................................... 41

Table 3.1: Current issues at Pimburaththewa Tank .............................................................................. 44

Table 3.2: Photographic evidence for the identified issues .................................................................. 47

Table 3.3: Material Requirements for the repairs at the spillway and construction of the bridge across

the spillway ........................................................................................................................................... 49

Table 4.1: Possible impacts due to the proposed interventions and their significance ....................... 57

Table 5.1: Proposed mitigatory measures for the identified impacts .................................................. 69

Table 5.2: General safety issues that need to be addressed ................................................................ 89

Table 5.3: Formal clearances and approval needed ............................................................................. 93

Table 6.1: Summary of monitoring requirement .................................................................................. 96

Table 7.1: Cost Estimate of EMP ........................................................................................................... 98

Page 9: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

viii | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ABREVIATIONS

AMSL - Average Mean Sea Level

BPL - Below Poverty Level

CEA - Central Environment Authority

D/S - Downstream

DBH - Diameter at Breast Height

DEM - Digital Elevation Model

DS Division - Divisional Secretariat Division

DSWRPP - Dam Safety & Water Resources Planning Project

EA - Environmental Assessment

EMP - Environmental Management Plan

EN - Species - Endangered Species

EPL - Environmental Protection License

FD - Forest Department

FFPO - Fauna and Flora Protection Act

GND - Grama Niladari Division

GoSL - Government of Sri Lanka

GPS - Global Positioning System

GSMB - Geological Survey and Mines Bureau

GTOP030 - Global 30 Arc-Second Elevation Data-Set

ICTAD - Institute for Construction Training and Development

ID - Irrigation Department

IDF - Intensify Durative Frequency Curve

IDF Curves - Intensity Duration Curves

IEE - Initial Environmental Examination

IML - Industrial Mining License

IUCN - International Union for Conservation of Nature

KPI - Key Performance Indicators

MSL - Mean Sea Level

NEA - National Environmental Act

PM - Project Manager

PO - Project Office

PS - Pradeshiya Sabha

RB - Right Bank

STRM - Global Multi Resolution Terrain Elevation Data

Page 10: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

ix | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

TEC - Technical Evaluation Committee

ToR - Terms of Reference

U/S - Upstream

VU Species - Vulnerable Species

WB – The World Bank

Page 11: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

x | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

TEAM OF CONSULTANTS FOR EA STUDY

Position Name Contact Details

Team Leader/Environmental

Engineer

Dr. Jagath Manatunge Mobile: 0718045546

e-mail: [email protected]

Natural Resource

Management Specialist

Prof. B. M. P.

Singhakumara

Mobile: 0714439300

e-mail: [email protected]

Ecologist Dr. Bandara Digana Mobile: 0777519671

e-mail: [email protected]

Socio-economist Mr. K. Jinapala Mobile: 0776595800

e-mail: [email protected]

Zoologist Prof. K. B. Ranawana Mobile: 0777356436

e-mail: [email protected]

Project Management MG Consultants (Pvt)

Ltd.

Address : 2nd Floor, 3, Swarna Place,

Nawala Road, Rajagiriya

Telephone: +94 11 2806028-9

Fax: +94 11 2806030

Mobile: +94 772 375822

e-mail : [email protected]

Page 12: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

1 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1. INTRODUCTION

1.1 PROJECT DESCRIPTION AND JUSTIFICATION

1.1.1 Background of the Project

Recent studies have revealed that major dams of the country are aging and suffering from various

structural deficiencies and short comings in operation and monitoring facilities. This situation

threatens the safety and operational efficiency of the dams and their appurtenant structures and as

a result increases the vulnerability of downstream populations and socio-economic infrastructure if

breached. The Dam Safety & Water Resources Planning Project (DSWRPP) intends to address these

issues through its dam safety and operational improvement component with financing from the

World Bank. One of the development objectives of the proposed project is to improve the

development and management of water resources within the country, reduce water induced

hazards to public, and enhance the effectiveness of water related investments. The proposed project

intends to address this issue in 29 dams through its dam safety and operational improvement

component. These dams have been identified as high risk with respect to their appurtenant

structures and operational efficiency. Those dams are required to have immediate interventions so

as to decrease the vulnerability of downstream populations and socioeconomic infrastructure if

breached. This situation threatens the safety and operational efficiency of the dams and their

appurtenant structures and as a result increases the vulnerability of breaching.

The Dam Safety & Water Resources Planning Project (DSWRPP) intends to address these issues

through its dam safety and operational improvement component with financing from the World

Bank. The main objectives of the proposed project are to improve the development and

management of water resources within the country, reduce water induced hazards to public, and

enhance the effectiveness of water related investments. The proposed project intends to address

these objectives in 29 dams through its dam safety and operational improvement component.

For these objectives are to be met, there will be some interventions to be carried out. These

interventions may bring about environmental degradations, environmental issues in terms of

physical, ecological or/and social changes, alterations or irreparable losses. Hence, the project needs

to identify such environmental issues that are very likely and they should be reduced or curtailed as

practical as possible. This Term of Reference (TOR) sets out the problems associated with four dams

which are operated by the MASL and proposes remedial works. The dams have been selected based

on comprehensive risk assessment studies carried out as part of project preparation from a list of

vulnerable dams in order to ensure their structural and functional safety. Under this TOR it is

expected to carry out Environmental Assessments for the proposed interventions under the

DSWRPP for Ulhitiya-Rathkinda, Henanigala, Pimburaththewa, Bambarawana, Pussalavinna and

Moogammana (See Figure 1.1).

This report is prepared with the objective of assessing the environmental impacts due to the

proposed interventions proposed for Pimburaththewa Tank under the DSWRPP.

The World Bank (funding Agency) and Dam Safety & Water Resources Planning Project (DSWRPP)

have agreed that the five dams earmarked for rehabilitation under this study need only an

Page 13: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

2 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Environmental Assessment (EA) together with an Environmental Management Plan (EMP) as the

proposed rehabilitation works do not entail any significant civil works.

Page 14: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

3 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.1: The seven reservoirs focused for the present cluster under the DSWRPP

Page 15: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

4 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.1.2 Project Location

This dam is located in System B agricultural zone managed by the MASL and is fed by Maduru Oya

LB main canal.

The administrative boundaries are:

District: Pollonnaruwa

Province: North Central Province

DS Division: Dimbulagala

The irrigable area under Pimburaththewa Dam is 6,516 acres and it is cultivated in both Yala and

Maha seasons. Fishing is the second most important livelihood activity that is based on water in the

Pimburaththewa reservoir.

The farmers in the irrigation system are organized in to organizations .The fishermen in the area also

have formed an organization for common benefits.

Water uses of Pimburaththewa Dam are:

Irrigation

Fishing - Fish production in system B is approximately, 5,000 ha of reservoir area: Maduru Oya Reservoir: 3,900 ha and Pimburaththewa Tank: 580 ha and the rest from smaller tanks.

Water for domestic purposes (bathing, washing, etc.)

A water supply scheme has been established in the immediate vicinity of the reservoir based on ground water

Figures 1.2-1.5 show the location of Pimburaththewa Reservoir.

Page 16: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

5 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.2: Location map of the Pimburaththewa Dam (Close-up view from Topo sheet)

Pimburaththewa Dam

Page 17: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

6 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.3: Map of System B. Pimburaththewa is fed directly by the Maduru Oya LB main canal. Pimburaththewa Reservoir is highlighted

Page 18: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

7 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.4: Location Map of Pimburaththewa Reservoir

Page 19: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

8 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.5: Land use of the area where Pimburaththewa Reservoir is located

Page 20: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

9 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.2 SCOPE OF THE PROJECT AND ENVIRONMENTAL ASSESSMENT

1.2.1 Scope of the Project

The technical scope of the study was to carry out environmental assessment based on the identified

interventions and their associated issues for the Pimburaththewa dam. The interventions to be

carried out during the rehabilitation work was defined at the inception stage of the project based on

the conceptual designs done by respective engineers and the environmental assessment related to

physical, ecological and socioeconomic environment will then be carried out.

1.2.2 Environmental Assessment Requirements

The strategies on which the environmental assessment conducted was based on the World Bank

Safeguard Policies and the National Environmental Regulations.

The World Bank Requirements

This environmental assessment was prepared pursuant to the World Bank’s Environmental

Safeguard Policies OP/BP 4.01 and that of Safety of Dams OP/BP 4.37.

The overall objective of the proposed environmental assessment was to carry out the following

conforming to the World Bank’s Environmental Safeguard Policies and Procedures. For each dam,

an Environmental Management Plan was prepared to address the objectives specified as given

below.

The World Bank Policies and Guidelines, pertaining to environmental safeguards that require

consideration under this project, as these will most likely be triggered, are as follows:

OP/BP/GP 4.01 Environmental Assessment

OP/BP/GP 4.37 Safety of Dams

OP/BP/GP 4.11 Physical Cultural Resources

OP/BP/GP 4.04 Natural Habitats

In addition, GP 4.11 is particularly applicable which details out the procedures to be followed for

chance find of physical cultural property. OP/BP 4.37 requires that the dam upgrading be designed

and its civil works be supervised by experienced and competent professionals.

Requirements under Environmental Regulations in Sri Lanka

The National Environmental Act (NEA) has made Environmental Assessments (EA) a legal

requirement for a range of development projects. A list of projects requiring an EA is prescribed in

Gazette (Extra Ordinary) No. 772/22 dated June 24, 1993. Accordingly, all river basin development

and irrigation projects excluding minor irrigation works requires an EIA, the guidelines are

ambiguous about the EIA requirement for upgrading and rehabilitation of existing dams. However,

agreement has been reached with the Central Environmental Authority (CEA) and Ministry of

Agriculture, Irrigation and Mahaweli Development that all dam upgrading and rehabilitation and

related activities financed under this project as well as any other activities that may lead to potential

adverse environmental impacts will be required to undertake an environmental impact assessment,

commensurate with the potential for environmental impacts and prepare detailed EMPs (including

a dam safety plan, where applicable) that will be included for implementation as part of the civil

Page 21: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

10 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

works Contractor’s contract documents.

The Fauna & Flora Protection Ordinance Act No. 49 of 1993 & its amendments: This Act provides

the protection, conservation and preservation of the fauna and flora of Sri Lanka. Under the Fauna

and Flora Protection Ordinance (FFPO), five categories of protected areas are established viz. Strict

Nature Reserves, National Parks, Nature Reserves, Jungle Corridors and Intermediate Zones

including sanctuaries. According to this Act, any development activity of any description what so

ever proposed to be established within a national reserve or within one mile from the boundary of

any national reserve, is required to be subjected to EIA/IEE, and written approval should be obtained

from the Director General, Department of Wildlife Conservation prior to implementation of such

projects. The FFPO follows a similar process as the NEA in conducting scoping, setting the TOR,

preparation of EA, review of EA and public consultation and disclosure. The decision of project

approval or disapproval is finally granted by the Director General of the Department of Wildlife

Conservation.

Forest Ordinance No. 17 of 1907 and subsequent amendments: The Forest Ordinance of Sri Lanka

is the law for conservation, protection and management of forest and forest resources for the

control of felling and transport of timber and forest related matters. The Forest Ordinance of No. 17

of 1907 amended by several Acts up to 1995 – Act 34 of 1951, No. 49 of 1954, No. 13 of 1966, No.

56 of 1979, No. 13 of 1982, No. 84 of 1988, and the new Act No. 23 of 1995.Under Section 4 of Act

No. 23 of 1995, the Minister is in charge of forests, has special powers to order and declare any

specified area of State land or the whole or any specified part of any reserve forest which has unique

ecosystems, genetic resources or a habitat or rare and endemic species of flora , fauna, micro-

organisms and of threatened species which need to be preserved in order to achieve an ecological

balance in the area by preventing landslides and fire hazards to human life, as a Conservation forest.

Under Section 5 of the Act, a Forest Officer of a specified area has special power to stop any public

or private way or watercourse in a reserved forest. It shall be lawful for the District Secretary to

determine the amount of compensation to be paid, in case that the water course injuriously affects

the interests or one or more individuals to whom on that account compensation should be paid.

1.3 OBJECTIVES OF THE STUDY

The objectives of this assignment are:

i. Identify and evaluate the potential environmental impacts that would arise as a result of the

proposed interventions

ii. Recommend appropriate mitigation measures to avoid, minimize, remedy or compensate for the

predicted negative impacts; and

iii. Provide a site-specific Environmental Management Plan that would give adequate project options

in terms of mitigation measures, project alternatives and a monitoring program to achieve overall

environmental sustainability of the project.

Page 22: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

11 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.4 METHODOLOGY

1.4.1 Mobilization

The team of consultants appointed by MG Consultants (Pvt) Ltd. commenced work on 10th February,

2015 with a meeting of team members where the Team Leader briefed the others regarding the

methodology for executing the consulting services. Documents required for the study were also

identified and team members requested to collect those pertaining to their areas of expertise. The

team leader thereafter prepared the Scope of Work for all team members to ensure that the

quantum of work to be carried out will be done in a uniform manner.

The requirement outlined in the TOR and the methodology was studied in depth and responsibilities

of each team member were identified. Topographic sheet were studied to observe the current land

use and the geographical features of the area.

Subsequent to the meeting, the Team Leader consulted the DSWRPP officials and obtained the

contact details of technical personnel who are in charge of respective dams. These technical

personnel were contacted appointment were made to meet them at respective offices and

requested them to facilitate the field visits and the reconnaissance field visit. The team visited all the

dams and their project areas. The team visited on individual capacity several times to gather and

collate necessary data from time to time.

1.4.2 Scoping Meetings and Reconnaissance Visits

The reconnaissance survey to Pimburaththewa Dam was carried out on 19th of February, 2015. The

team visited the dam and its project areas, accompanied by Mr. A. D. Wijeratne, who is the Block

Manager of Wijayabapura Block Office.

The main issues and the proposed interventions were identified during the reconnaissance survey

by having several meetings with key stakeholders in order to reach consensus on the issues and

mitigation measures required. Meetings were held with DSWRPP and MASL officials, farmer /

residents / in the project vicinity and fishermen engaged in inland fishery activities. Findings

gathered during these meetings helped to refine our approach to the study and to focus on the

following:

a. Proposed physical intervention – scale and nature of the intervention: Identification of physical

interventions including field inspections with the officers to assess the issues and magnitude of the

interventions.

b. Review of the work plan and Implementation schedule, including the time frame; Discussion with

relevant officers/engineers at the MASL and other relevant stakeholders at the site to familiarize

with the critical issues that are affecting the safety of the dams.

The details of the potential impacts due to proposed development interventions will be collected in

the follow up field studies to the reservoir area. The client’s confirmed list of development

interventions will be used for the impact identification with their magnitude in the next field studies

after Inception report is accepted by the client.

Page 23: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

12 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.4.3 Data and Information Collection

A detailed literature review of available data was done by the team of consultants at the project

initiation. Relevant data to identify impacts were collected during a reconnaissance visit as and when

available, and also desk studies. The data gaps were identified and the detailed field plan was

prepared to carry out baseline surveys.

1.4.4 Baseline Surveys

This basically dealt with collection of background data through primary and secondary sources.

However, where appropriate, surveys, investigations both in situ and ex situ were undertaken. The

study area for the assessment included the dam and bund area, peripheral area (500 m minimum),

burrow areas, work site and any area beyond the project site where there is potential for

environmental impacts and off site locations affected by construction activities. In this context, the

details of water users (agriculture and other such as fishing, domestic etc.) were collected to review

the diversity and magnitude of multiple water users in the Pimburaththewa reservoir.

Establishment of baseline conditions included establishment of present and future state of the

environment, in the absence of the project, taking into account the changes resulting from natural

events, and from any disaster that can take place due to dilapidated condition of dams and related

infrastructure.

An ecological survey was carried out to describe the existing baseline conditions to evaluate and

illustrate the magnitude of the problem. This identified major habitats / flora and fauna including

communities in and around the sites and to assess possible ecological impacts, existing

environmental problems within the proposed project areas. The study area confined to the specific

locations and immediate surroundings directly affected by the activities.

Fauna and flora found in all habitats of the project area were recorded by walking along transects to

get a rapid assessment of the species diversity. The conservation status of the species was

determined according to the National Red List of Sri Lanka (2012).

Social surveys and related studies were carried out covering all the stakeholders, especially the

farmer and fishing communities in addition to other water users (e.g., villagers who use the water

for day-to-day activities, and/or other purposes). Grama Niladharis, Economic Development Officers,

Samurdhi Niyamakas, officials of the farmer organizations, and any other governmental officers who

are directly or indirectly involved with the functioning of the dam and its water resources (such as

the Divisional Secretariat, MASL). The data on number of different water users such as farmers,

fishermen, families depending on tank water for domestic purposes (drinking, bathing and washing

etc.) were collected. Data and information gathered from such social surveys were used to identify

and assess social impacts. Mitigation measures were proposed with clear justifications based on the

expectations of the stakeholders.

Page 24: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

13 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.4.5 Identification and assessment of impacts, nature and magnitude

The EA identified environmental issues that may arise as a result of project activities especially

considering impacts that can arise affecting natural habitats, natural resources and also on the social

environment (especially, water users in the tank). Impacts can be classified into several categories

depending on the nature of impacts.

(a) Interventions that will cause moderate to significant impacts (if not mitigated)

(b) Interventions that will cause impacts that are direct, while some other may have indirect

impacts.

(c) Interventions that will cause impacts in the longer term rather than immediately following

the intervention:

(d) Activities of certain interventions will yield only minor impacts that are short term and easily

mitigated;

All the interventions and their implementation (Table 3.1) were closely studied and compared with

environmental elements in order to find out the impact caused by every activity on the every

environmental element. Physical, biological and social including socio-economic parameters were

considered for environmental elements. Some of the socio-economic parameters that were used for

monitoring the impacts are included below (Table 1.1) and there can be changes on these depending

on the findings of the detail field studies.

Table 1.1: Data that need to be collected during the detailed study

Criteria Indicators Data need

Livelihoods of the

farming community

No of farmers/ families to be affected

The land area affected ( encroached

land in the downstream and

upstream of the reservoir)

Details of cultivators under

the tank, yield and income,

details on encroachments of

the reservations.

Other indirect

livelihoods

No of drinking water users affected

No of fishing families affected

No of families used tank water for

bathing and washing

Data on the other water

uses in the tank

Disturbances to

other routine

activities of the

communities in the

project area

No of families in villages used the

tank bund top as access

Data on users of the tank

bund top as access road

1.4.6 Institutional Arrangements

The Acts, regulations, licenses, permits and other approvals that may be necessary for the

implementation of the proposed interventions were identified. These may include;

Page 25: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

14 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

(a) Irrigation Ordinance No. 32 of 1946 Irrigation (Amendment) No. 1 of 1951 Irrigation

(Amendment) No. 48 of 1968 Irrigation (Amendment) No. 37 of 1973 Agrarian Development

Act, No. 40 of 2002

(b) The National Environmental Act (NEA) No. 47 enacted in 1980 and NEA Amendment Act No.

56 of 1988

(c) National Environmental Protection and Quality Regulations under extraordinary gazette

notification No. 1534/18 and No. 1533/16 of 2008 under NEA section 32 & 23A, 23B

(d) Fauna and Flora Protection Act (FFPO) No.2 of 1937 amended in 1993 and 2009

(e) Felling of Trees Control Act No. 9 of 1951 as amended through Act No. 30 of 1953

(f) Water Resources Board Act, No. 29 of 1964 and (Amendment) Act, No. 42 of 1999

(g) Soil Conservation Act, No. 25 of 1951 and Amended No. 24 of 1996

(h) Agrarian Development Act No. 46 of 2000 (Section 32)

(i) Antiquities Ordinance No. 9 of 1940 and amendments

(j) Mines And Minerals Act (No. 33 of 1992)

(k) Mahaweli Authority of Sri Lanka Act of 1979

(l) World Bank Guidelines pertaining to Dam Safety & Environment Assessment Guidelines

It is also imperative that the proper institutional arrangement be made available for smooth

operations of the EMP. It is the Project Office that is in charge of the entire project and the client,

Irrigation Department would be solely responsible in getting the project implemented with a

selected contractor.

The contractor will be selected through a bidding process and the contractor is responsible in

implementing the EMP delineated herein this report. During the project implementation period, the

World Bank and the Project Office will evaluate the implementation of the EMP. Once the EMP is

implemented as per the World Bank Safeguard Policy Documents, review of implementation of EMP

would be done in order to ensure that all negative impacts are addressed successfully.

1.4.7 Environmental Impact Analysis, Proposed Mitigatory Strategies and preparation of the

Environmental Management Plan (EMP)

The objective of preparing the EMP is:

(i) To propose appropriate mitigation measures to reduce or minimize any adverse impacts

that have been identified, taking into account any associated constraints or consequential

environmental or social implications of such measures;

(ii) To identify, predict and evaluate the acceptability of the residual impact of the project after

the implementation of selected mitigation measures and to estimate and evaluate any

cumulative environmental impacts to which the project may contribute;

Page 26: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

15 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

(iii) To identify, develop and specify methods, measures and standards to be included in the

operational phases of the project to reduce environmental impacts to acceptable levels;

Appropriate mitigation will be proposed to ensure the identification of potential environmental

issues and social concerns early in the implementation of a proposed project to incorporate

necessary safeguards in project design in order to prevent potential adverse impacts by determining

appropriate mitigation.

A site-specific EMP that will provide mitigation strategies, project alternatives and a plan for

monitoring programme will be prepared. Proper management of the catchment and the watershed

is essential for ensuring continued economic benefits envisioned from the dam are met. These will

also be considered in the EMP.

1.4.8 Preparation of the Environmental Monitoring Plan (EoMP)

The Project Proponent needs to implement a comprehensive environmental monitoring programme

soon after implementation of proposed interventions. This is very crucial in order to assess the

performance or success of the implemented mitigatory measures. There are 3 basic environmental

monitoring tasks to assess the success of mitigation and identifying residual impacts. They are;

Pre-construction monitoring to determine the baseline conditions in detail to identify impacts and

mitigation measures and costs

Construction compliance monitoring, and

Post construction monitoring of maintenance and operational project activities.

It should be noted that during the construction phase both the contractor and the Project Proponent

should accept a major responsibility in undertaking the monitoring aspects with assistance from

competent authorities. With reference to undertaking environmental management issues,

monitoring aspects and implementation of mitigatory measures to prevent environmental impacts

an Environmental Monitoring Unit (EMU) should be established. This study will identify the

composition of this unit, its role and responsibilities etc.

In addition, for each significant impact, the environmental monitoring plan (EoMP) will propose:

- Mitigation measure

- Indicators/parameters to be monitored

- Frequency of monitoring – Time bounded monitoring

- Responsible entity for monitoring – institutional arrangements

- Responsible entity for supervising – institutional arrangements

Page 27: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

16 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.4.9 Preparation of the cost estimate for implementation of the EMP and EMoP

Cost estimates for implementing the EMP and the EoMP will be prepared.

1.4.10 Recommendations and Conclusions

Findings and suggestions of the EA Report will assist the Project Proponent in formulating an

environmentally friendly and a socially acceptable project and to achieve the broader objectives of

the proposed project.

1.4.11 Documentation Procedure

Draft final reports EMP for each Dam will be submitted summarizing the findings of the study and

will be finalized after incorporating the comments.

1. Inception Reports for each Dam

Including the Physical Interventions finally proposed to be carried out at the site (project activities),

Construction Methodology, Equipment to be used, Pre construction activities, etc., outline of the

Potential Environmental Impact on Physical and Social Environmental and outline of the proposed

Mitigation Measures. The inception report will also highlight the areas where impacts may be

possible due to proposed Dam safety project in Pimburaththewa Dam. The areas of impact will be

studied in detail in the follow-up field studies after Inception report is accepted by the client.

2. Draft Final Reports for each Dam

The Final Report will include the following:

A comprehensive Environmental Management Plan (EMP) to manage the onsite as well as offsite

environmental impact comprising the following.

(i) Mitigation strategies for each impact identified

(ii) Appropriate institutional arrangement to implement the proposed measures

(iii) Implementing schedule

(iv) Reporting procedures

(v) Cost estimates for implementing mitigation measures

- Environmental monitoring plan that will specify monitoring indicators to measure the

performance of the each mitigatory measure, monitoring mechanism and frequency.

- Clearance approvals needed by the project prior to its implementation

- Recommendations on the adequacy of the assessment

- Final Conclusions and recommendations regarding environmental viability, of the

project based on the findings

- Annexures and Appendices

Page 28: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

17 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

3. Submission of Final Reports

The Final Report will be submitted within two weeks after receiving comments from the client once

the TEC evaluates and reviews the Draft Final Report. The final report will be reviewed by the World

Bank as well.

The main activities to be followed to complete above deliverables are summarized in Work Plan

given below (Table 1.2).

Page 29: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

18 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 1.6: Proposed Approach and Methodology for the Study

Establishment of the baseline:

(i) Physical Environment (Topography, Geology and Soil, Meteorology, Hydrology, Land use and Water and Air Quality etc.)

(ii) Social surveys (iii) Ecological Surveys including

migratory paths

Collection of data and information (mainly from MASL);

Clarification sessions with the Client; Meetings with other

Stakeholders

Identification of proposed project interventions / Activities as

outlined in the TOR for the Study

Report

Identification of potential impacts during:(i) Project

Preparation, (ii) Implementation of individual interventions,

both identified and proposed (iii) resource consumption, (iv)

handling and disposal of waste, (iv) implementation schedule

Assessment of magnitudes of impacts and interventions and

evaluation of the impact significance

Identification and development of mitigation measures and

preparation of the Environmental Management Plan (EMP)

plan

Preparation of the Environmental Monitoring Plan (EMoP)

Preparation of Cost estimates for implementation of the

EMP and EMoP

Conclusions and Recommendations

Page 30: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

19 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.5 EXPECTED OUTCOMES OF THE REPORT

The expected outcomes are categorized as follows.

(a) Comprehensive Environmental Management Plan (EMP) to manage the on-site as well as

off-site environmental impacts

(b) An environmental monitoring plan that will specify the monitoring indicators to measure

the performance of the each mitigatory measure, monitoring mechanism and frequency

(c) Clearance approvals needed by the project prior to its implementation

(d) Recommendations on the adequacy of the assessment

(e) Recommendations regarding the environmental viability of the project based findings

Page 31: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

20 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

1.6 WORK PLAN

The steps described above can be summarized as a work plan as follows (Table 1.2)

Table 1.2: Work plan for the proposed environmental study

ACTIVITY

Month 1 2 3 4

Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14

1. Project initiation, Meetings with

DSWRPP and Engineers of MASL

2. Data and Information Collection

3. Reconnaissance surveys and field

visits

4. Preparation of Detailed

Methodology and Scoping of

environmental issues

5. Establishment of the baseline

environment

6. Identification and assessment of

impacts, nature and magnitude

7. Identification of Mitigation

Strategies and preparation of the

EMP

8. Preparation of the Environmental

Monitoring Plan (EoMP)

9. Preparation of the cost estimate

for implementation of the EMP

and EMoP

10. Recommendations and

Conclusions

11. Receiving Client’s comments

12. Drafting and Submission of Reports

1 2 3

Note: Submission of Reports:

1. Inception Report – at the end of Week 2

2. Draft Final Report – at the end of Week 10

3. Final Report – at the end of Week 14

Page 32: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

21 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 1.3 provides the details of the tasks assigned for each team member including the team leader.

All the key experts in the Consultancy Team have the qualifications and the experiences as stipulated

in the TOR.

Table 1.3: Tasks assigned to each team member and the responsibility

Main Discipline/Task Key Expert Responsible

Coordination of the entire assignment Team Leader and Support staff

Preparation of overall methodology Team Leader

Detailing the interventions and Scoping of environmental

issues to identify impacts

Activities related to environmental (physical) aspects

Environmental Engineer/ Natural

Resources Management

Specialist/Chartered Civil Engineer

Meeting with stakeholders, including officials from

DSWRPP and MASL (including TEC meetings)

The entire team led by the Team

Leader

Description of the baseline:

- Physical environmental aspects

- Ecological/Biological impacts including migratory

mechanisms

- Sociological aspects

Environmental Engineer

Ecologist and Zoologist/ Faunal

Specialist

Sociologist

Drafting EMP and EoMP:

- Physical environmental aspects

- Ecological/Biological impacts

- Sociological/Economic aspects

Environmental Engineer

Ecologist and Zoologist/Faunal

Specialist

Sociologist

(input from Natural Resources

Management Specialist as needed)

Calculation of costs; Drafting Conclusions and

Recommendations

Team Leader with inputs from

other key experts

Drafting of the reports Team Leader with contribution

from other team members

Page 33: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

22 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

2. DESCRIPTION OF THE EXISTING ENVIRONMENT

2.1 OVERVIEW

It is imperative that the existing environment in the project area and the borrow areas are identified

in terms of different environmental elements. In order to perceive the likely alterations of the

existing environment due to the proposed interventions present status of the existing environment

needs to be recorded and then the impacts on such elements need to be discussed.

In general, the entire existing environment is described in three main components, namely, physical,

ecological and socioeconomic environments respectively. Data were collected focusing on these

three components and are presented below.

2.2 PHYSICAL ENVIRONMENT

The south part of the project area, occupied by that portion of the Maduru Oya basin which drains

to the Maduru Oya reservoir, is separated from the Mahaweli Ganga valley by a north–south line of

hills of height up to about 670 m above sea level. These hills are Precambrian in origin, in common

with the underlying formations throughout the project area. The link tunnel that diverts water from

the Mahaweli Ganga into the Maduru Oya reservoir, and the subsequent cascade system (to which

Pimburaththewa tank belongs to) penetrates this line of hills. A spur from the northern end of this

range traverses the Maduru Oya valley in a generally southeasterly direction.

a. Climate

The Pimburaththewa tank is located in the Maduru Oya basin, which falls within the dry zone of Sri

Lanka, where notable dry season occurs with an annual rainfall under 1,900 mm. The dry climatic

conditions are said to be prevailing most of the time where cooler climate is expected only in the

northeast monsoon period.

b. Temperature

At an average temperature of 28.7 °C, May is the hottest month of the year. In January, the average

temperature is 25.1 °C. It is the lowest average temperature of the whole year. Relatively minor

temperature fluctuations are normally experienced compared with wider fluctuations in

precipitation and streamflow. The variation in annual temperature is around 3.6 °C.

Page 34: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

23 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.1: Monthly average, high and low temperature in Aralaganvila near Pimburaththewa tank area

(Source: http://en.climate-data.org/location/765864/)

c. Rainfall

The Maduru Oya basin experiences a tropical climate, falling under the influence of the northeast

[December to February] and southwest [May to September] monsoons. The northeast monsoon

(Maha) brings most of the annual rainfall, and therefore runoff, in the catchment area. The

southwest monsoon (Yala) is typically dry due to the orographic effect of the Central Highlands of

Sri Lanka. Rainfall in the inter-monsoon periods can be caused by either convective or cyclonic

storms. Relatively minor temperature fluctuations are normally experienced compared with wider

fluctuations in precipitation and streamflow. The latter fluctuations have important implications for

the development of rain fed and irrigated agriculture.

It is envisaged from the Figure 2.2 that the substantial rainfall in the project area occurs in the first

and second inter-monsoon periods falling in between March to April and October to November,

respectively. The highest average monthly rainfall recorded during last 5 years ranged between 380

- 420 mm. Precipitation is the lowest in June, with an average of 18 mm. Most precipitation falls in

December, with an average of 412 mm. Annual average rainfall is around 1,900 mm. Between the

driest and wettest months, the difference in precipitation is 394 mm.

Page 35: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

24 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.2: Monthly average rainfall in Aralaganvila near Pimburaththewa tank area

(Source: http://en.climate-data.org/location/765864/)

d. Wind

Wind data has not been recorded continuously in the vicinity. The Welikanda Meteorological Station

has no data collected for Wind after 1979.

The average wind patterns on a typical day would be between 5 – 20 km/h. However, this can rise

to about 30 – 35 km/h during the north east monsoon periods. Occasional high winds can be

expected any time during September – November and during mild troughs or cyclonic circulations

e. Topography

The general topography of Sri Lanka comprises of three distinctive peneplains or erosion plains made

up of a central highland massif rising above 2,500 meters in altitude and a low gently undulating

plain surrounding it and extending to the sea. The lowest peneplain extends from the coastline to

approximately 20-30 kilometres inland in a steep step of about 300 meters above mean sea (MSL).

Maduru Oya basin is located in the Eastern Province, lies within this lowermost peneplain. The

landscape in the vicinity of the site is characterized by flatlands with almost no altitude changes

partly due to the fact that the land has already been cleared and prepared for the cultivation,

secondary development with people in-migrating to these areas recently. There are stepped lands

of 2~3 meters in height and exposure of reddish soil in some parts of the area. It is evident from the

location and contour maps that Pimburaththewa is aligned in the northeastern direction, in parallel

to the pre-existed (natural) flow direction of Maduru Oya.

Page 36: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

25 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

According to the present topographical variation, the downstream of the tank is characterized by

undulating slopes with 2.5% – 4.5% surface gradient in north-west direction. There are isolated

hillocks which have altitudes upto of 210 m MSL. According to the pre-existed topography, the

elevation in the area is approximately 60 – 80 m MSL with a gently sloping landscape in the north-

west direction and also towards the southeastern direction.

Page 37: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

26 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.3: Topography of the Area (Note: Pimburaththewa and Maduru Oya (South of Pimburaththewa) are both located below the 100 m contour line)

Page 38: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

27 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

f. Soil and Geology

The geology of the area is characterized by Precambrian rocks. They have given rise to a mature,

mantled and undulating peneplain which mere imperceptibly to the north and northeast into the

pleistocene and Miocene sediments of the coastal plain. Large, prominent and isolated erosion

remnants and prominent rides rise to heights of over 400 m [Gunner’s Quoin] above the general

level of the surrounding plain. The elevation of the latter varies from about 80m above sea level in

the south to under 30 m in the extreme north. The mantle covering the peneplain rock is generally

thin and sometimes nonexistent, as in areas of rock knob plain and outcropping flat rock.

Two very different soils have developed on the Precambrian rocks. On those rice in ferromagnesian

minerals, moderately deep to shallow (100 cm), reddish to brown, sandy clay loam soils have

developed, on slopes which often exceed 2 percent and sometimes 4 percent. These soils normally

occur in association with prominent rock outcrops. On the rocks relatively poor in ferromagnesian

minerals but rich in quartz, moderately deep to shallow, grey brown, loamy sand and sandy loam

soils occur. These overlie impermeable rocks and usually occur on slopes not exceeding 4 percent.

The soils of the upper slopes tend to be ‘moderately well’ to ‘well drained’ while those of the lower

slopes tend to be ‘imperfectly drained’.

Associated with these soils are ‘imperfectly’ to ‘poorly drained’ bottomland and old alluvial soils of

variable but usually sandy texture. These old alluvial soils are not necessarily associated with the

present – day drainage. A relatively wide band of ‘imperfectly’ to very poorly drained’ recent

alluvium [with the exception of a low, narrow, moderately freely draining levee soil occurs along the

Maduru Oya and the Mahaweli Ganga.

Page 39: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

28 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.4: Distribution of Soil Groups (Panabokke, 1975)

Page 40: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

29 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

g. Hydrology

The Pimburaththewa sub-catchment and the stream network contributing to the flows are located

within the Agro-ecological Region DL2, in the Hydrological Region 2.

Pimburaththewa Tank is located in the Northern part of the main catchment Maduru Oya Basin

(Figures 2.5, 2.6 and 2.7). The main basin consist of a catchment of 1,452 km2, and characterized by

a series of reservoirs in a cascade pattern along main channels and their tributaries, associated main

supply, distributary and return flow canals and their flow control structures including slices, gates

and minor anicuts.

The main hydrologic data required for the hydrological and hydraulic assessments apart from the

topographic information are;

Rainfall Intensity-Duration-Frequency Curves (IDF Curves) for catchment areas

Information on runoff coefficients and time of concentration

The site is situated in the belt of monsoon climates and governed by its tropical location as well by

the monsoonal regime, thus rainfall exhibits a strong seasonal variation. More than 50% of the total

rainfall is received during the Second Inter Monsoon and North-Eastern Monsoon (October to

December).

Except for the low-lying downstream catchment sections (60 - 80 m AMSL) in the most downstream

of the Maduru Oya Basin, the majority of the eastern coastline is covered with a narrow ridge of

mountain protruding above 200 m rising out of flat terrain leading to invert/reverse flow conditions

at several sections south-east. However, the Pimburaththewa sub-catchment is located in the

further upstream (80-100 m AMSL) and away from the downstream regional floodplain. Therefore,

the sub-catchment area is presumably not subjected to any flooding under seasonal monsoonal

storm event, except for extreme events where backwater flows from downstream accumulation due

to flow constrictions may cause localized temporary inundation in some areas. Historical flood data

are not available in the area.

The topographic data with contours and road layout has been obtained from the Survey

Department. Topographic maps with 1: 50,000 scale were primarily used (1: 10,000 maps were not

available) together with the collected Global Positioning System (GPS) coordinates to locate the

manor canals and structures while supplementary topo - and land use information from Google Earth

maps, Google terrain data and other relevant images have also been obtained as required. The

SRTM/GTOPO30 (USGS) global raster satellite DEM (Digital Elevation Model) data were downloaded

and used in identifying sub-/major catchments in the region. These maps and terrain data in

combination with identified land use data were used to distinguish and demarcate respective

catchment areas for the tank under consideration. In the present version of the analysis, a 5.0-m

interval contour map in the coast of upstream region, developed based on DEM data from GTOPO30

and modified with SRTM (Refined) arc 3.0 data has been used in initial catchment demarcation.

Page 41: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

30 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.5: The catchment areas of the Reservoirs/Tanks considered for the present EA

Page 42: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

31 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.6: The satellite view of the catchment areas of the Reservoirs/Tanks considered for the present EA

Page 43: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

32 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.7: Main Pimburaththewa Catchment

Page 44: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

33 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

h. Flooding

Past flooding records indicated that the project area was inundated with the flood received in

January 2013 but damages were not significant. The flood water level had receded within a short

period of time, hence no significant flood damage was recorded. All seven sluice gates of the Ulhitiya

Rathkinda reservoir have been opened both in 2013 and 2014. The water is being released to the

Mahaweli River. The Rathkinda-Hobariyawa and Mahiyangana-Dehiattakandiya roads were flooded.

Even the floodwaters have damaged the Ulhitiya Oya Bridge.

The Maduru Oya floodplain, when it was in the unregulated state before early 1980s, experienced

short duration flooding during the Maha season. For example, the cyclone of November 23/24, 1978

caused widespread flooding. Substantial flood control benefits have been derived from the flow

regulation of the Mahaweli River in the floodplain area, particularly in the reduction of the

magnitude and duration of persistent flooding during the Maha season. More intense flood peaks

have affected less, since the effects of an intense storm event than smaller watershed area

downstream from the dam has causes a larger peak flow per unit area than would have resulted

from the same storm over the entire catchment.

Therefore, no flood damages were recorded in the recent past, at least for last 30 years.

i. Noise and Vibration

Background noise levels in the area were found to be very low varying in the range of 45 – 58 dB (A)

during the site visit, indicating that no any artificial noise levels is generated in the project area. The

existing noise levels are attributed by the noise generated from the rattling of leaves of trees by the

wind and the occasional screech of birds passing and roosting in the area.

No significant vibration levels were perceived during the field visit indicating that vibration induced

activities were almost absent.

j. Air Quality

Occasional wind blows were observed during the site visit, which have been a common site in the

bund area. Such sporadic wind blowing has brought about airborne suspended particles, but, this

scenario was not significant enough to be reckoned as an issue. The canopy trees that have rooted

down in the vicinity of the bund have sheltered the bund area from escaping the airborne particles

hence, no air quality issues were found. Occasional vehicular movements were recorded along the

bund, which sometimes causes the airborne particles to be locally present. However, during the

windy periods, one has to be aware of airborne particles causing inconvenience to the pedestrians.

k. Water Quality

The water quality of the tank seems to be not degraded as relatively less anthropogenic activities

are found to be operating in the surrounding of the tank. It has been consistently observed that the

average pH is 8.4, which shows slight alkalinity in water (average: 5.5 meq/l), probably due to the

geological formations. Chlorophyll concentrations are moderate with an average value of 58.5 mg/l,

Page 45: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

34 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

which shows slight eutrophic conditions. Apart from the algal growth, slight turbidity issues were

seen during the site visit, particularly in the area of rip rap as the soil underneath was stirred up due

to wind induced currents striking the rip rap. This issue was very much localized and was not

considered to be an adverse issue for aquatic ecosystems.

2.3 BIOLOGICAL ENVIRONMENT WITH FLORA AND FAUNA

2.3.1 Existing Habitats and ecological significance

Pimburaththewa tank is located within the dry zone of the island in Polonnaruwa district. Natural

vegetation types in this area belongs to the ‘Dry and Arid Lowlands’ floristic region. The typical

natural climax vegetation types expected to be found in this zone are tropical dry-mixed evergreen

forests (Manilkara and mixed community) tropical thorn forest, damana and villu grasslands, flood

plain wetlands and riverine and gallery forests. However, these habitats are not found in the area

where the project interventions are planned. Agro-ecologically this area is classified as DL1c- low

country dry zone with undulating terrain and Reddish Brown Earth and Low Humic Gley as typical

soil types. The land use includes paddy lands, rain-fed upland crops, mixed home gardens,

scrublands, and natural forests. This tank is found in Mahaweli system B close to the Aralaganwila

town. Maduru oya National Park is the nearest protected area. Ecologically sensitive habitats such

as natural undisturbed forests or wetlands are not found where the proposed intervention will be

implimented. Both aquatic and terrestrial habitats are found in the project area. The aquatic habitats

are the tank and water stagnated habitats below the dam. Two main terrestrial habitats based on

the floristic composition are cultivated lands, and tank bund/ reservation. The tank reservations are

properly maintained without any encrochments. Seapage area of the downstream include severl

stagnated water pools with extensively growth green algae. Shallow areas of the tank has been

colonized by Japan jabara (Eichhornia crassipes). Large extents of paddy fields are located

downstream area away from the tank.

2.3.2 Flora

Tree species such as Milla (Vitex altissima), Ehela (Cassia fistula), Kohomba (Azadirachta indica) Kon

(Schleichera oleosa), Helamba (Mitragyna tubulosa), Ehatu (Ficus tinctoria), Rukattana (Alstonia

scholaris), Kumbuk (Terminalia arjuna), Nuga (Ficus benghalensis) Bo (Ficus religiosa), Ipil ipil

(Leucaena leucocephala), and Damba (Syzygium cumini) are found in the reservation of the dam.

The common herbs, shrubs and climbers found on the tank bund are Lantana (Lantana camara), Katu

pila (Flueggea leucopyrus), Iluk (Imperata cylindrica), Podisinnomaran (Eupatorium odoratum), Epala

(Urena lobata), Rata tana (Panicum maximum), Bevila (Urena lobata), Nidi kumba (Mimisa pudica),

Pani thora (Cenchrus echinatus), Wal Aba (Cleome viscosa), Kuwani (Cenchrus echinatus), Eraminiya

(Ziziphus oenoplia), Kala wel (Derris parviflora), Gas Karal Heba (Achyranthes aspera), Heen eraminiya

(Ziziphus oenoplia), Bowitiya (Osbeckia aspera), Monara Kudumbiya (Vernonia cinerea), Kappetiya

(Croton laccifer), Karamba (Carissa spinarum), Ranawara (Cassia auriculata), Bo kala wel (Derris

scandens), Maduru thala (Ocimum tenuiflorum), Wara (Calotropis gigantean), and Hulan Tala

(Ageratum conyzoides).

Page 46: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

35 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Home gardens and residences located away from the tank include several species of trees such as

Amba (Mangifera indica), Kos (Artocarpus heterophyllus), Siyambala (Tamarindus indica), Tekka

(Tectona grandis), Coconut (Cocos nucifere), Halmilla (Berrya cordifolia) Kohomba (Azadirachta

indica), and Acacia (Acacia melanoxylon).

2.3.3 Invasive Species

Two species of invasive plants were observed from the tank and surrounding habitats include aquatic

plant, Japan jabara (Eichhornia crassipes) and terrestrial species Lantana ( )aLacLaLatLaLL ).

aLacLaLatLaLrL is curently spreads in tank bunk, tank reservation and surrounding habitats. Since

periodic removal of weeds from tank bund, distribution of aLacLaLa tLaLrL is controlled to some

extent. A few bushes of Lantana can be seen in fences around the cultivations and uncultivated lands.

An invasive aquatic species Japan Jabara (Eichhornia crassipes) can be seen as small patches in shallow

areas of the tank.

2.3.4 Fauna

Pimburaththawa spillway could be considered as an artificial habitat. The spillway is concrete lined

and reinforced with boulders and iron mesh. Therefore, the spill way is not a preferred wildlife

habitat. Shallow reservoir side near the spillway support a luxuriant growth of water hyacinth

(Eichhornia crassipes). This is a favorable habitat for some water birds such as Indian Pond Heron

(Ardeola grayii) and Little Egret (Egretta garzetta). Summary of the fauna recorded in the spillway

area is given in the Table 2.1.

Table 2.1: Summary of the fauna recorded in the rubble storage site and Pimburaththewa

spillway site

GROUP Species Endemic CR EN VU

DRAGONFLIES 3 - - - -

BUTTERFLIES 32 1 - - -

AMPHIBIANS 3 - - - -

REPTILES 6 - - - -

BIRDS 30 2 1 - -

MAMMALS 6 2 - 1 -

CR- Critically endangered ; EN- Endangered; VU-Vulnerable

List of fauna recorded in Pimburaththewa site is given in the Annex 4.

2.3.5 Rare, Threatened and Endemic Flora and Fauna

The habitats in the project area are degraded due to human influence. Therefore, plant and animal

communities found in natural undisturbed habitats are not represented in these areas. Only two

threatened species namely the Rock Pigeon (Columba livia – critically endangered) and Elephant

Page 47: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

36 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

(Elephas maximus – endangered) were recorded from the project site. Further, five endemic animal

species namely one butterfly species (Sri Lanka Lesser Albatross- Appias galena), two birds (Sri Lanka

Junglefowl - Gallus lafayetii and Sri Lanka Lesser Flameback -Dinopium sarodes), and two mammals

(toque monkey -Macaca sinica and Sri Lanka pigmy mouse deer- Moschiola meminna) were also

recorded.

2.3.6 Migratory Paths

There are evidences (dung piles, tree branch damages etc.) to prove that elephants frequent the

spillway area probably for drinking and bathing in the shallow reservoir area near the spillway.

Elephants may be moving to the area from the forests bordering the reservoir which is connected to

the Maduru Oya National Park (Figure 2.8). Although, the spillway proper is not a preferred elephant

habitat, the areas bordering the spillway would be providing the suitable cover for the elephants

visiting the reservoir.

Figure 2.8: Pimburaththawa spill

2.3.7 Proposed borrow area

In the past the site has been used for solid extraction and hence still carries some open patches

(Plate 2.3.2). Invasive shrub Lantana camera (gandapana) dominate the open area while a good

tree cover exists along the border of the site. The tree covered areas of the site is a quality bird

habitat as evidenced by presences of large number of birds in the area. Thirty species of birds have

been recorded from trees surrounding the site (Table 2.1). There are indirect evidences (tree &

branch damage, signs of antler rubbing, and fecal pellets etc.) to prove this tree cover is regularly

used by the large herbivores such as elephants and spotted deer which visit the spill area for drinking

purposes.

Elep

han

t mo

vem

en

ts

Page 48: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

37 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 2.9: Rubble storage site

2.4 SOCIOECONOMIC ENVIRONMENT

2.4.1 Local Administrative Units in the Project Area

The Pimburaththewa Dam is the reservoir located in Mahaweli System B. The Pimburaththewa

reservoir and it is related other features are located in Dimbulagala Divisional Secretariat of

Polonnaruwe District in North Central province. The irrigation Dam is administrated by Welikanda

Resident Project Manager's (RPM) office and Wijayabapura Block Managers’ (BM) office. The specific

details of the local administrative units related to the project are mentioned below:

Page 49: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

38 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 2.2: Details of the local administrative units related to the project area

Part of the dam Province District Relevant RPM

Relevant BM Relevant DS Relevant GN Relevant villages

Tank and Tank catchment

North central

Polonnaruwa Walikanda Wijayabapura Dimbulagala 236, Pimburattawa East

238, Pimburattawa west

Pimburattawa

Command area North central

Polonnaruwa Walikanda Wijayabapura Dimbulagala 236, Pimburattawa East

238, Pimburattawa west

245, Aralaganwila west

246, Aralaganwila east

247, Rathmaltanna

248 track 5

254 Wijayabapura

255 Gomathiyaya

256, Madagama

257, Jayapura

Pimburattawa

Aralaganwila

Rathmaltanna

track 5

Wijayabapura

Gomathiyaya

Madagama

Jayapura

Deagama

Bamunakotuwa

Sudupalama

Chethiya pitiya

Madurutenna

Galthalawa

Farmers -do- -do- -do- -do- -do- -do- -do-

Page 50: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

39 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

2.4.2 Land Use in Different Areas of the Irrigation Schemes

Catchment Area

The catchment area of this reservoir has not been encroached and developed for any economic

activities. The catchment is in Maduru Oya reserved forest area. The extent of Catchment of this

reservoir including its water spread areas is about 1784 ha.

Downstream of the Dams

Downstream of the Dam has not been encroached by anybody for any economic or social activity.

Command Area

The total command area of the reservoir is 2724 ha with distribution among 63 Farmer organizations

(FOs). The cultivation activities of this command area are managed by 8 Unit Managers’ offices.

These 8 Unit Managers’ areas fall under 10 Grama Niladhari divisions for other civil administrative

purposes.

The entire command is cultivated with paddy in both Maha and Yala seasons (100% cropping

intensity).

2.4.3 Demographic Data Relevant to the Project Area

Table 2.3: Details of Project Relevant Population

Relevant GN Units No of FOs

No of families

Land owning families

Families not owning land

Pimburattawa East

8 63 410 360 50

Pimburattawa West

357 303 54

Aralaganwila East 430 270 160

Aralaganwila West

833 678 155

Rathmaltanna 413 250 153

track 5 288 216 72

Wijayabapura 589 310 279

Gomathiyaya 251 190 61

Page 51: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

40 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Madagama 436 223 213

Jayapura 378 201 177

Total 1 63 4385 3011 1374

There are no human settlements in catchment areas or downstream areas of the Dam. The farmers

have not established any houses in the paddy land areas. All the farming families of the two

reservoirs are residing in settlement areas/hamlets (highlands) falling under Kadirapura Grama

Niladhari division.

2.4.4 Economic Activities of Project Related Population

The distribution of income generation activities among families in the project related 10 GN divisions

is given in Table below

Table 2.4: Distribution of income generation activities among families in project related villages

Economic Activity Percentage of Families

Farming 70

Government employment 15

Private sector employment 10

Others (fishery, small business & foreign employment) 5

Source: FO leaders, GNs

2.4.4.1 Yield and Income from Agriculture

Paddy farming is the main source of income of the project relevant families in Pimburaththawa

Irrigation scheme. According to the leaders of the farmer organizations and the officers of

Mahawanawala Block Office interviewed (Annex 5) yield of the farmers in the scheme are fairly

homogeneous. Therefore, the information related to one farmer on yield and income of an acre

cultivated with paddy is mentioned below as representative case of Pimburaththawa irrigation

scheme.

Yield – 2,420 kg per acre per season (110 Bushels x 22 kg)

Selling price and the gross income – 2,420 kg * Rs 36/- = Rs 87,120/-

Average expenditure – Rs. 46,600/-

Net income – Rs 40,520/- per season (Rs. 87,120 – Rs.46,600)

Further details of the calculation of cost benefit are shown in Annex 2.

Page 52: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

41 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

2.4.4.2 Cost Benefit Analysis of the Yield and Income from the entire irrigation scheme

The team further worked out the cost benefit of the entire Pimburaththewa irrigation scheme with

the experience of the leaders of farmer organizations and the Officers of Wijayabapura Block Office.

The details expressed by them are summarized below:

Table 2.5: Details Expressed by the Farmer Leaders/Block Officers

Yield Gross income Rs. Expenditure items Expenditure Rs.

Total land area = 6,810 acres

Yield of an acre = 2,420 Kg

Total Yield = 2,420 * 6,810= 16,480,200 kg

Rs. 593,287,200

(16,480,200 kg * Rs. 36/-)

Total land area 6,810 acres, expenditure of 1 acre per season Rs. 46,600/-,

Total expenditure of the entire scheme 317,346,000 (6,810 * 46,600)

Note:

Total gross income – Rs. 593,287,200/-

Total expenditure – Rs. 317,346,000 /-

Net income – Rs. 275,941,200/-

2.5 OTHER WATER USES

Three other (other than agriculture) direct and 1 indirect water uses and users of Bund top as access

are reported in Pimburaththewa irrigation scheme areas. The details of these water uses are

described below:

Fishing Activities

Fishing is a significant economic activity taking place in Pimburaththewa tank. About 105 persons

actively involved in catching fish in the tank. They have 105 boats used for fishing. The 105 fishermen

have formed an association called “Lihini Inland fishery cooperative “. About 20 persons are full time

fishermen and they solely depend on this activity for their livelihoods. They earn about Rs. 1,000 to

1,200 /day and about 20 days /month they go for fishing in the tank. The other persons perform

agriculture activities in the irrigation scheme as part time income generation activity. They too earn

about Rs. 1,000 but they spend only about 10 days for fishing during agriculture season and they

have freedom to go for fishing for about 20 days/month during off agriculture season. The 105

fishermen use 3 locations as boat landing sites. The 3 boat landing sites include:

Mulgalpedesa- 70 boats

Alawakumbura – 30 boats

Talawe- 5 boats

Page 53: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

42 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Drinking water use

A community water supply scheme has been recently established but house connections have not

yet been given. It has been planned to provide water to 500 families.

Bathing and Washing

About 25 to 30 families use the tank for bathing and washing. Others in the pimburattawe area use

irrigation canals for this purpose. When the irrigation canals are closed (during August and

September) the communities in the area use the tank for bathing and washing.

Small Industries

About 26 rice mills are available in the project area and their performance is completely depended

on the agriculture (1 large scale mill and 25 minor scale mills). Another about 20 mills use for rice

processing and grain milling are also available.

Use the bund top as access road

The bund top is not used as a permanent road. Some families, about 15 to 20 use the bund top as

temporary/by pass access to reach Chenas (Chenas in Sadunpura, Lihiniyagama and Weheragala

areas).

2.6 CURRENT ENVIRONMENTAL ISSUES OF THE PROJECT AREA

This subsection discusses the other issues pertaining to the area other than those to be caused by

the project activities. The project activities may trigger some of them, resulting in adverse impacts.

Hence it is of paramount to mention such issues in brief in order to lessen such impacts, if envisaged.

2.6.1 Physical Issues

The runoff from the agricultural fields enters the reservoir. Villagers may use this nutrient loaded

water (including heavy metals) for drinking and bathing purposes. Excessive nutrients entering the

reservoir may lead to eutrophication and appearance of algal blooms.

2.6.2 Ecological Issues

There are no significant ecological issues identified in the proposed project area. Some invasive plant

species such as Lantana, Japan Jabara and guinea grass are found in the natural habitats, tank and

tank bund/ toe areas. The periodic cutting of Lantana and guinea grass controls their colonization in

the terrestrial habitats. Presence of invasive species prevents the establishment of indigenous herbs,

shrub and some tree species in these habitats. Human elephant complicit is not a major issue in the

Pimbureththewa tank and surrounding habitats. Herds of elephants frequently visit the spillway and

surrounding area and occasionally raid the crops and damage the properties of the people.

2.6.3 Socioeconomic Issues

One of the most serious problems faced by the communities, especially farmers is the frequent

entering of wild elephants to the area. These elephants come to the residential and agriculture areas

Page 54: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

43 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

from the Maduru Oya reserved forest. The crops in the areas such as Pimburaththawe East,

Pimburaththawe West, Aluth Oya, Aralaganwila East and Aralaganwila West are frequently

destroyed by wild elephants.

Lack of land resources (both irrigated and high lands) is another serious and also long term problem

related to the livelihood of the people. A family has been allocated with 1 ha of irrigated land and

0.25ha of highland. These extents are not at all adequate to divide among children (average family

size is 5 to 6). A plot of land belongs to a family can be divided in to two parts but if there are more

than one child it would be a serious problem for land distribution among all the children.

Lack of opportunities for non-agriculture employments and also fluctuation of paddy selling prices

are also viewed as problems in the area.

Page 55: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

44 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

3. PROPOSED INTERVENTIONS

3.1 PROPOSED ENGINEERING INTERVENTIONS

A list of current structural and operational issues of the dam was given to the consultants for

verification during the reconnaissance field visit. The consultants verified the issues in the provided

list to them and also included other issues not yet included in the original list. The issues verified by

the consultants and also the new issues identified with the assistance of MASL officers of the Dam

are summarized in Table 3.1.

Table 0.1: Current issues at Pimburaththewa Tank

Issues identified as per the ToR

Issue Intervention Construction methodology

1. Inadequate

capacity of

the spillway

canal

2. Erosion in

spillway side

ways

3. Deficiencies

in spillway

(Figures 3.1 – 3.8)

Removal of existing gabion structure

Excavation of spillway approach channel

Repair to the spillway side walls

Repair of spillway bed and stilling basin

Removal of the existing concrete road

Excavations for spill way construction

Construction of embankments to support the bridge deck

Construction of the bridge over the spillway

Construction of the road on the bridge and on either sides of the bridge

Painting of the bridge

Slope protection

Site Clearing

Clearing and uprooting of secondary growth jungle including

removal of all trees

Demolishing, removing of existing concrete road and cut off

wall

Removing of gabion boxes

Stripping top soil, haul 1 km

Earth works

Common excavation for structures, approach canal and

disposal of waste material or used for fill

Common excavation for foundation and use for backfilling or

disposal of waste material

Construction of coffer dam and removing after construction

Filling of bund FSL to bund top

Borrow earth from borrow areas, cut 0-10 ft lift up to 10 ft,

any haul

Placing and compacting earth in embankment & in trench

including watering

Rock excavation

Soft rock excavation and spoil to waste, haul 1 km

Rock excavation and spoil to waste/ Quarry product, haul 1

km

Slope protection

Furnishing, Planting and watering turf, haul 1.6 km including

loading

Furnishing and placing gravel bedding, haul 1.6 km including

loading

Furnishing and placing 450 mm rip-rap, haul 1.6 km including

loading

Concreting

Grade 15 concrete (1:3:6 (40 mm) for screed concrete in

structures excluding form work

Page 56: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

45 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Grade15 concrete (1:3:6 (40 mm) for screed concrete in

structures including formwork

Grade 20 concrete (1:2:4 (20 mm) in structures including

formwork

Grade 20 concrete (1:2:4 (20 mm) in structures including

formwork

Grade 25 concrete (1:11/2:3 (20 mm) in structures including

formwork

Grade 30 concrete in structures including formwork

Grade 40 concrete in structures including formwork

Reinforcement

Furnishing, cutting, bending and placing toe steel

reinforcement

Furnishing, cutting, bending and placing mild steel

reinforcement

Precast concrete Units

Furnishing and install bridge beams 32’×2.59t & transport

200 miles, installation crane travel 200 miles

Furnish and install kerb slab 3’×1.08 cwt, transport 200 miles,

installation crane travel 200 miles

Furnish and install uprights for hand rails of 3’3”×1.09cwt,

transport 200 miles, installation crane travel 200 miles

Furnish and install hand rails of 3” dia×7’81/2”×0.94cwt,

transport 200 miles, installation crane travel 200 miles.

PC concrete coupling pairs for hand rails of bridge supplying

and fixing

Water Stop

Supplying and laying of 225 mm width center bulb rubber

water stop at construction joints

Miscellaneous Works

Supplying and laying approved hard rubber bearing pads 75

mm × 12 mm over capping beams

Supplying and fixing M.S. Angle Iron and hard rubber

expansion joints as per drawing.

Supplying and fixing 110 mm dia PVC extended pipe type 250

through deck rain water outlets as per drawing

Supplying and placing asphalt wearing surface at bridge deck

and approaches

Painting with two coats of enamel paint on kerbs, uprights,

hand rails and parapet walls of bridge

Supplying and fixing 25 mm dia 400 mm long stainless steel

dowel bars.

Bituminous sealing material supplied and laid under beam

ends to prevent Grout leak on to.

230 mm dia. polythene displacers supplied and filled with

saw dust or similar light material in deck.

Forming weep holes using PVC pipes of int. diameter not less

Page 57: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

46 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

than 100 mm, complete with drip ledge and surround finish

smooth

Slope protection with 9” thick pitching in 6’’×9” rubble in

1:5ct. mt. on rubble pitching faces

4. Damage in

the rip rap in

some areas

(Figure 3.9 and 3.10)

Placing rip rap

Removing of existing riprap and pilling of riprap rubble

manually

Transport of riprap rubble (about 16 km) to the site and

piling

Packing of removed or additional new ruble to a thickness of

375 mm manually

Placing and packing riprap to a thickness of 450 mm

Issues identified during the initial site visit

Issue Intervention Construction methodology

5. Seepage

areas along

the

downstream

toes (Figure

3.11 & 3.12)

Construction of Toe road and toe drain

Construction of V-notches

Weeding along the tank bund

Removing of embankment unsuitable material, including

stripping of top soil on dam slope and dam toe, cut and lift

up to 1.5 m, haul 30 m

Furnishing and laying of a geo textile cloth in toe drain

Furnishing, placing, spreading, watering and compaction of

20-37.5 mm well graded aggregate layer as the bottom layer

of toe filter

Furnishing, placing and packing 150-300 mm of well graded

rubble in toe drain

Furnishing, placing, spreading, watering and compaction of

gravel as fill material for access road by machinery

Full turfing to newly filled earth in canal bund slopes

Furnishing and installation of V-Notch and Culvert across

the road in toe filter

Note : Apart from the development interventions initially proposed and also observed in the

consultants' field visits the farmer leaders met during the detailed filed studies mentioned about

their concerns to get the tank bed desilted. The tank bed is silted up seriously (about 5 feet depth

with sediments).

Photographic evidence for the identified issues in Table 3.2 is given in figures below.

Page 58: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

47 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 3.2: Photographic evidence for the identified issues

Figure 3.1: Damages to the Spillway Figure 3.2: Erosion in spillway side ways

Figure 3.3: Damaged Spillway

Figure 3.4. Spill tail areas collapsed completely

Figure 3.5: Damaged spillway Figure 3.6: Damaged Spillway

Page 59: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

48 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Figure 3.7: Completely eroded parts of the Spillway

Figure 3.8: Completely eroded parts of the Spillway

Figure 3.9: Removal of shrubs needed on the rip rap rip rap in some areas

Figure 3.10: Riprap damaged at some places

Figure 3.11: Seepages at D/S areas Figure 3.12: Seepage at D/S areas

Page 60: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

49 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

3.1.1 Resource and Material Requirements for Proposed Interventions of Pimburaththewa Reservoir

Table 3.3: Material Requirements for the repairs at the spillway and construction of the bridge across the spillway

Item of work

Clearing

(m2/Ha)

Excavation/ Removal Earth/Sand/Rubble (m3)

Material Need

Nos. Gravel/Earth/ Sand (m3)

Rubble/ Aggregate (m3)

Concrete (m3)

Linear meters (m)

Square meters (m2)

Site Clearing

Clearing and uprooting of secondary growth jungle including removal of all trees

0.53

Ha

Demolishing, removing of existing concrete road and cut off wall

468.5 m3

Removing of gabion boxes 480 m3

Stripping top soil, haul 1 km 340 m3

Earth works

Excavation for structures, approach canal and disposal of waste material or used for fill

38,043.9 m3

Common excavation for foundation and use for backfilling or disposal of waste material

2,971.8 m3

Construction of coffer dam and removing after construction

01

Nos.

Filling of bund FSL to bund top

Page 61: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

50 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Item of work

Clearing

(m2/Ha)

Excavation/ Removal Earth/Sand/Rubble (m3)

Material Need

Nos. Gravel/Earth/ Sand (m3)

Rubble/ Aggregate (m3)

Concrete (m3)

Linear meters (m)

Square meters (m2)

Borrow earth from borrow areas, cut 0-10 ft lift up to 10 ft, any haul & Placing and compacting earth including watering

7,915.5 m3

Rock excavation

Soft rock excavation & spoil to waste, haul 1 km 50 m3

Rock excavation and spoil to waste/Quarry product, haul 1 km

90 m3

Slope protection

Furnishing, planting & watering turf, haul 1 km 2,099 m2

Furnishing & placing gravel bedding, haul 1 km 120.8 m3

Furnishing & placing 450 mm rip-rap, haul 1 km

310.5

m3

Concreting

Grade 15 concrete (1:3:6 (40 mm) for screed concrete in structures

289.9

m3

Grade15 concrete (1:3:6 (40 mm) for screed concrete in structures

1,175

m3

Grade 20 concrete (1:2:4 (20 mm)

2,454

m3

Grade 20 concrete (1:2:4 (20 mm)

296

m3

Page 62: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

51 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Item of work

Clearing

(m2/Ha)

Excavation/ Removal Earth/Sand/Rubble (m3)

Material Need

Nos. Gravel/Earth/ Sand (m3)

Rubble/ Aggregate (m3)

Concrete (m3)

Linear meters (m)

Square meters (m2)

Grade 25 concrete (1:1½:3 (20 mm)

950

m3

Grade 30 concrete in structures

124

m3

Grade 40 concrete in structures

261

m3

Reinforcement

Furnishing, cutting, bending and placing toe steel reinforcement

222 t

Furnishing, cutting, bending and placing mild steel reinforcement

6 t

Precast concrete Units

Furnishing and install bridge beams 32’×2.59t & transport 200 miles, installation crane travel 200 miles

168

Nos.

Furnish and install kerb slab 3’×1.08cwt, transport 200 miles, installation crane travel 200 miles

292

Nos.

Furnish and install uprights for hand rails of 3’3”×1.09cwt, transport 200 miles, installation crane travel 200 miles

236

Nos.

Furnish and install hand rails of 3” dia×7’81/2”×.94cwt, transport 200miles, installation crane travel 200 miles.

342

Nos.

Page 63: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

52 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Item of work

Clearing

(m2/Ha)

Excavation/ Removal Earth/Sand/Rubble (m3)

Material Need

Nos. Gravel/Earth/ Sand (m3)

Rubble/ Aggregate (m3)

Concrete (m3)

Linear meters (m)

Square meters (m2)

PC concrete coupling pairs for hand rails of bridge supplying and fixing

348

Nos.

Water Stop

Supplying and laying of 225 mm width center bulb rubber water stop at construction joints

434 m

Miscellaneous Works

Supplying and laying hard rubber bearing pads 75 mm × 12 mm over capping beams

97.5 m

Supplying and fixing M.S. Angle Iron and hard rubber expansion joints

97.5 m

Supplying and fixing 110 mm dia PVC extended pipe type 250 through deck rain water outlets

56 m

Supplying and placing asphalt wearing surface at bridge deck and approaches

61

Mt

Painting with two coats of enamel paint on kerbs, uprights, hand rails and parapet walls of bridge

190 m2

Supplying and fixing 25 mm dia 400 mm long stainless steel dowel bars.

154

Nos.

Bituminous sealing material supplied and laid under beam ends to prevent Grout leak on to.

182 m

Page 64: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

53 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Item of work

Clearing

(m2/Ha)

Excavation/ Removal Earth/Sand/Rubble (m3)

Material Need

Nos. Gravel/Earth/ Sand (m3)

Rubble/ Aggregate (m3)

Concrete (m3)

Linear meters (m)

Square meters (m2)

230 mm dia. Polythene displacers supplied and filled with saw dust or similar light material in deck.

1,232 m

Forming weep holes using PVC pipes of int. diameter not less than 100 mm, complete with drip ledge and surround finish smooth

42 m

Slope protection with 9” thick pitching in 6’’×9” rubble in 1:5ct. mt. on rubble pitching faces

1,170 m2

Page 65: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

54 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

3.2 PROPOSED BORROWING ACTIVITIES AND IDENTIFIED BORROW SITES

3.2.1 Turfing Materials

The turfing materials are required to prevent the soil erosion in slopes during the rainy season. The

grasses suitable for turfing are available in tank beds and in open grounds close to the tanks.

3.2.2 Earth

A site located near southern end of the pimburaththawa dam spill has been selected as a borrow

area to extract soil for the construction work of Pimbureththewa dam site.

3.2.3 Metal

The metal would be obtained from a private metal quarry in Siripura area.

3.2.4 Sand

Sand mining of Mahaweli river is carried out by the GSMB at Manampitiya. Sand could be purchased

at Manamptiya or if another location is selected a permit for extracting sand from the river would

be required from the Geological Survey and Mines Bureau (GSMB).

3.2.5 Gravel

A site located at Devagama has been selected as borrow area to extract soil and gravel for the

construction work of Pimbureththewa dam site.

The location for the above identified burrow and quarry sites are given in Annex 3.

3.3 PROPOSED INTERVENTIONS THAT COULD AFFECT NEIGHBORING COMMUNITIES

The design engineering team of Dam safety project assume that proposed development

interventions to repair the rip rap will be implemented during water low period of the tank ( just

after Yala season harvesting ). If the contractor cannot complete the proposed sensitive

development interventions within the short dry sell there may be need to keep the tank with low

water levels or postpone the sensitive construction work to the next season where tank would

experience low water levels. If water level is lowered there will be disturbances to the cultivation

planning in the irrigation scheme. Rehabilitation of spillway is the most essential need under the

proposed dam safety development interventions. The engineers of the project assume that

rehabilitation of spillway can be completed without lowering of the tank water levels. There can be

some temporary disturbances to the local communities who use to access their villages/Chena

through an informal road falling across the existing spillway.

Almost all the interventions will affect the neighboring communities for a certain extent; however,

they are not significant. Following interventions that have been proposed can be listed as

interventions that could affect neighboring communities:

Page 66: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

55 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Material transport, stockpiling especially for graveling the bund road, rip rap construction,

correcting the slopes of the bund etc.

Constructing the rip rap, providing clay cutoff wall, etc. will obstruct the movements along

the bund

Providing toe filters, toe drain and the toe road along the toe area of the dam

Rehabilitating the bund (including construction of the rip rap) will prevent access to the tank

3.4 PROPOSED INTERVENTIONS THAT COULD AFFECT THE NATURAL HABITATS

The natural habitats found in the proposed project area and the identified borrow site are highly

degraded. The natural undisturbed habitats or vegetation formations are not found in the project

site or in the borrow site. The existing degraded habitats do not contain critical elements of

biodiversity such as endemic or threatened species confined to the dry zone of Sri Lanka. The plant

species found in these habitats mainly represented by the pioneer/ secondary species, exotic weeds

and invasive species. Threatened and endemic species do not encounter in these degraded habitats.

The proposed project interventions such as pilling of riprap rubble, packing of removed or additional

new ruble, do not make major disturbances to the existing habitats. Removal of trees is minimal for

any of the activities. Uprooting of herbs, shrubs and climbers in the rip rap area should be carried

out before repairing the rip rap. The clearing of herbs and shrubs will have temporary impacts on

some faunal species, e.g. butterflies and birds, since they depend on nectar of flowers and fruits of

these species. However, individuals of these plant species are found in the nearby habitats and

therefore the impacts would be negligible.

Page 67: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

56 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

4. PROJECT INDUCED IMPACTS

4.1 IDENTIFICATION OF PROJECT INDUCED IMPACTS

Note: The anticipated impacts described under this section are mainly for the construction phase only.

However, any impacts that are induced during operational stages (if any) are also presented where

applicable. The impacts are confined to negative impacts, as the positive impacts as a result of

improved dam safety and improved operational capacities of Head works are obvious and perceived.

Impacts were classified into three categories:

No: Environmental effects are perceived to have been no change at all.

Low: Environmental effects are not detectable or are so minor that they will neither destabilize nor

noticeably alter any important attribute of the resource.

Moderate: Environmental effects are sufficient to noticeably alter important attributes of the

resource, but not to destabilize them.

High: Environmental effects are clearly noticeable and are sufficient to destabilize the resource.

Table 4.1 depicts the possible impacts together with their significance on each intervention

proposed.

Page 68: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

57 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 4.1: Possible impacts due to the proposed interventions and their significance

Issues identified as per the ToR

Issue Intervention Anticipated Impacts Significance

1. Inadequate

capacity of the

spillway canal

2. Erosion in

spillway side

ways

3. Deficiencies in

spillway

Removal of existing gabion structures

Excavation of spillway approach channel

Repair to the spillway side walls

Repair of spillway bed and stilling basin

Excavations for spillway construction

Removal of the existing concrete road

Construction of embankments to support the bridge deck

Construction of the bridge over the spillway

Construction of the road over the bridge and on either side of the bridge

Painting of the bridge

Slope protection

Impact on ecological environment:

Adverse Impact of the nearby habitats in spillway area will occur during the

construction phase. Removal and uprooting of trees and secondary growth

vegetation is essential for the proposed repair work to the spillway. Majority

of trees trees in spilway area ara planted trees belongs to exotic species

Acacia (Acacia melanoxylon). Since these trees have been used by the

avifaunal species this will create habitat loss for water birds roosting in these

these trees. Also negative impacts in borrow sites due to the removal of soil/

gravel would be expected. Excavated pits need to be filled to prevent

accidental damage to the wild animals, collecting rain water, and creating a

habitat for mosquito breeding during the rainy season.

Low Moderate

Impact on social environment:

This will be fairly significant and time consuming construction activity in this

dam. If it gets delays there can be some implications to fill the tank up to its

FSL level. Some community members’ access their villages/chenas through

an informal road across the spill way and there can be some disturbances to

these community members during construction period.

Moderate

Impacts on physical environment:

Removal and disposal of debris and excavated material

This activity involves the clearing of about 0.53 Ha of land and demolition of

the existing concrete road (469 m3) and stripping of top soil (340 m3). The

existing gabion boxes will be removed (480 m3), which will be part of the

Moderate

Page 69: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

58 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

construction material (this will partially satisfy the need of requirement of

rubble). Part of the existing riprap will be completely removed and the

surface has to be prepared for subsequent re-laying of the riprap. The

surface preparation will produce significant amounts of soil material which

need disposal.

Increasing the possibilities of erosion

The proposed construction need significant amounts of soil excavation

(38,043 m3 of excavation for structures and 2.971 m3 for foundations)

before construction of the spillway, spillway bed and the stilling bed.

Embankment construction and road construction involved in the bridge

construction need stripping of top soil, excavation of embankments, filling

and compaction. Such earth work will lead to soil erosion, slope erosion and

erosion of the road surfaces.

Raw water quality of surface water bodies

Raw water quality of surface water bodies can be affected due to soil

erosion. Soil particles that enter nearby water bodies, such as the tank and

canals etc., can result in temporary turbidity problems. However, the

duration of this exposure is short in duration and hence adverse impacts

anticipated would be not be significant.

Hindrance to vehicular movements, damage to the crest road surface

due to movement of heavy vehicles, temporary storage of earth along

the crest road and elsewhere

The earthwork involved in the construction work is large (41,000 m3).

Borrow material once brought to the site (7,915 m3) has to be unloaded and

stockpiled for subsequent use. This might block the existing run on and off

paths which may create erosion problems elsewhere.

Material transport (7,915 m3 of earth; approx. 5,000 m3 of concrete) may

Moderate

Moderate

Moderate

Page 70: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

59 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

result in congestion of local roads. There are dwelling units along haulage

routes and elevated levels of traffic matter can become a minor temporary

adverse impact during the construction period. Movement of heavy vehicles

will damage the crest road and access roads in the vicinity.

Noise and vibration

Large amounts of earth work (more than 41,000 m3 of earth excavation,

demolition of the existing road surface (468 m3), stripping of the top soil (340

m3) and most of the other activities will generate noise. Compacting large

areas and large amounts of concrete will generate significant amounts of

noise. Much of the proposed work will be carried out using machinery.

However, small machinery will be used for excavating and rubble and earth

transport. Noise and vibration is expected to be significantly high due to the

large-scale nature of construction.

Dust generation

Large amounts of earth work (more than 41,000 m3 of earth excavation,

demolition of the existing road surface (468 m3), stripping of the top soil (340

m3) and most of the other activities would produce airborne dust, which are

temporary and limited to short durations and will be restricted to a small

area. Therefore, air pollution due to the proposed work can be considered

not significant.

Pollution of Soil and Water via Fuel and Lubricants

The earthwork, large amounts of concrete work, and erection of the bridge

need a large fleet of heavy vehicles and heavy machinery. Activities such as

operation of construction vehicles, parking areas, fuel/lubricants spills

storage sites, machinery and equipment maintenance and refueling will

generate pollutants that have the potential to pollute soil and water.

Moderate

Moderate

Low

Page 71: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

60 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Construction and removal of coffer dams

Transport of sheet piles, driving and removing of the sheet piles cause

numerous impacts. Noise and dust can result from transportation activities.

Noise and vibration due to pile driving and removing can cause disturbance

to neighboring community and the wildlife.

Sheet piles should be able to cutoff water movements across the coffer dam

for facilitating the construction activities.

(It is assumed that construction of the coffer dam would be done only after

a thorough hydrological and geological study. This should aim at prevention

accidental damage of the coffer dam structure due to predictable water

level fluctuations and the bottom geology would be capable enough to

support the sheet piles in withstanding hydraulic pressures.)

Health and sanitation of worker’s camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Management of waste (other than construction and excavated material)

and wastewater

Significant quantities of construction waste (e.g., during stripping of top soil)

are expected. In contrast, food items even in small quantities may attract

stray animals. However, the overall impact is very low.

Safety of workers at work

The earthwork involved in the construction work is large (41,000 m3).

Borrow material once brought to the site (7,915 m3) has to be unloaded and

stockpiled for subsequent use. The prestressed concrete sections have to be

Moderate

Low - moderate

Low

Moderate

Page 72: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

61 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

unloaded, and subsequently handled carefully to erect the bridge. These

activities pose a severe hazard and potential to cause physical injury to

workers during moving heavy loads downhill/uphill.

4. Damage in

the rip rap

in some

areas

Placing rip rap

Impacts on ecological environment:

Removal of existing vegetation in the rip rap, mainly herbs and shrubs will have some impact on butterflies and birds. However the impact will be low due to availability of similar habitats in surrounding area.

Low

Impacts on social environment:

If rip rap rehabilitation cannot be completed within the water low period in

the tank there may be need to lowering the water level or to postpone the

work to the next water low period of the tank

Low

Impacts on physical environment:

Increasing the possibilities of erosion of the U/S slopes

Exposed areas of the bund are susceptible to erosion.

Hindrance to surface runoff, hindrance to vehicular movements during

temporary storage of material along the crest road and elsewhere

Borrow material once brought to the site has to be unloaded and stockpiled

for subsequent use. This might block the existing run on and off paths which

may create erosion problems elsewhere.

The quantity to be handled seems to be large hence the impact may be

relatively significant (exact quantity to be determined)

Raw water quality of surface water bodies

Runoff through material borrow areas and unloading sites could lead to

wash off of soil particles to nearby water bodies such as canals, tanks

streams etc. resulting in temporary turbidity problems. However, the

Low

Low

Low

Page 73: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

62 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

quantity to be handled seems to be very low, hence adverse impacts

anticipated would be insignificant.

Hindrance to vehicular movements, damage to the crest road surface

due to temporary storage of rubble among the crest road and elsewhere

Material transport may result in air pollution through giving rise to elevated

levels of airborne dust. There are dwelling units along haulage routes and

elevated levels of airborne particulate matter can become a minor

temporary adverse impact during the construction period.

Health and sanitation of worker’s camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Management of waste (other than construction and excavated material)

and wastewater

No significant quantities of construction waste are expected. In contrast,

food items even in small quantities may attract stray animals. However, the

overall impact is very low.

Generation of noise, vibration and dust affecting the social and biological

environment

Noise and vibration can occur during compaction of the aggregate layer and

related activities. Activities that would produce airborne dust are temporary

and limited to short durations and will be restricted to a small area.

Low

Low

Low

Low

Page 74: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

63 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Pollution of Soil and Water via Fuel and Lubricants

Activities such as operation of construction vehicles, parking areas, fuel/lubricants spills storage sites, machinery and equipment maintenance and refueling will generate pollutants that have the potential to pollute soil and water.

Safety of workers at work

Placing the rubble for the riprap will be done manually. Placing and moving

rubble from the bund crest towards the bund slopes involve extensive

amount of manual labour work. These activities pose a severe hazard and

potential to cause physical injury to workers during moving heavy loads

downhill/uphill.

Low

Moderate

Issues identified during the initial site visit

Issue Intervention Anticipated Impacts Significance

5. Seepage areas

along the

downstream

toes

Construction of Toe road and toe drain

Construction of V-notches

Impacts on ecological environment:

Removal of existing vegetation in the toe area, herbs, shrubs and few trees. The impact will be low due to availability of similar habitats in downstream area of the tank.

Low

Impacts on social environment:

No impacts are expected because there is adequate land area that can be used to establish the toe road and other infrastructure facilities required in the downstream of the Dam

Low

Impacts on physical environment:

Need to dispose debris and excavated material away from the site

Construction of the toe filter and drain include removing the existing toe

drain, excavation and removal of unsuitable soil material, bed formation

and stripping of soil. Further, construction of the toe road also involves

stripping of top soil and exaction of soil. These are significant amount that

Moderate

Page 75: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

64 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

has to be disposed properly (quantities of these material have to be

determined after designs are completed).

Increasing the possibilities of erosion of the toe areas in the D/S

Construction of the toe drain, filter and the tow road involve stripping of top

soil and loose rubble in the filter. Such exposed areas of the bund toe area

are susceptible to erosion.

Hindrance to surface runoff

Construction of the toe filter and drain include removing the existing toe

drain, excavation and removal of unsuitable soil material, bed formation

and stripping of soil. Construction of the toe road also involves stripping of

top soil and exaction of soil. These will pile up at the construction site, which

will hinder surface drainage.

Construction of the toe filter and drain need sand, graded gravel, and

rubble. Toe road construction needs earth and gravel. These materials once

brought to the site have to be unloaded and stockpiled for subsequent use.

This might block the existing run on and off paths which may create erosion

problems elsewhere (quantities of this material have to be determined after

designs are completed).

The quantity to be handled seems to be fairly large hence the impact may

be moderately significant.

Raw water quality of surface water bodies

Runoff through material borrow areas and unloading sites could lead to

wash off of soil particles to nearby water bodies such as canals, tanks

streams etc. resulting in temporary turbidity problems. However, the

quantity to be handled seems to be very low, hence adverse impacts

anticipated would be insignificant.

Low

Low

Low

Page 76: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

65 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Increase in vehicular traffic during transport of construction materials

Material transport may result in air pollution through giving rise to elevated

levels of airborne dust. There are dwelling units along haulage routes and

elevated levels of airborne particulate matter can become a minor

temporary adverse impact during the construction period.

Health and sanitation of workers’ camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Management of waste (other than construction and excavated

material) and wastewater

No significant quantities of construction waste (other than the excavated

material as described above) are expected. In contrast, food items even in

small quantities may attract stray animals. However, the overall impact is

very low.

Generation of noise, vibration and dust affecting the social and

biological environment

Noise and vibration can occur during compaction of the gavel bedding for

the toe road, loading berm, drains etc. and compacting the aggregate layers.

Activities that would produce airborne dust are temporary and limited to

short durations and will be restricted to a small area.

Pollution of Soil and Water via Fuel and Lubricants

Activities such as operation of construction vehicles, parking areas, fuel/lubricants spills storage sites, machinery and equipment maintenance

Moderate

Low

Low

Low

Low

Page 77: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

66 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

and refueling will generate pollutants that have the potential to pollute soil and water.

Safety of workers at work

Placing the rubble for the toe filter will be done manually. Placing and

moving rubble towards the bund slopes involve extensive amount of

manual labour work. These activities pose a severe hazard and potential to

cause physical injury to workers during moving heavy loads downhill/uphill.

Installation of the V-notches and three piezometers will have very minor

environmental impacts.

Low

Low

Page 78: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

67 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

4.2 QUANTIFICATION OF THEIR SIGNIFICANCE

Determining the significance of impacts places value on impact magnitude. It relates to the

importance society places on the resources affected, the importance of the impact to system

stability and sustainability.

Quantification of impact magnitude in this study has been objective-based backed by prior

experience of the team of consultants, rather than applying numerical and/or scientific principles

and theories. Once the impact magnitude was determined based on the proposed construction

methodology for each intervention, each expert has decided on the significance of the impacts based

on their area of expertise. Significant impacts will be the focus of mitigation measures and

subsequent monitoring, as outlined in the report.

Factors that have been considered in determining of impact significance include (but are not limited

to):

Area of Influence: Impact significance is often directly related to the size of the area affected.

Amount of Resource Usage: The greater the amount of resource usage, the more significant

the impact.

Status of Resources: Impacts due to usage of limited resources are usually considered more

significant than impacts to common or abundant resources.

Persistence of Impacts: Permanent or long-term changes are usually more significant than

temporary ones. The ability of the resource to recover, after the activities are complete, is

related to this effect.

Sensitivity of Resources: Impacts to sensitive resources are usually more significant than

impacts to those that are relatively resilient to impacts.

Regulatory Status: Impacts to resources that are protected (e.g., endangered species, air

quality, cultural resources, water quality) typically are considered more significant than

impacts to those without regulatory status.

Societal Value: Some resources have societal value, such as archaeological, cultural and

sacred sites, traditional practices, and recreational areas.

Hence, quantification of impacts was done based on the above-mentioned criteria only for the

impacts that are perceived to be either moderate or high.

There will be no negative social impacts if the contractors could complete the spillway rehabilitation

and rip rap rehabilitation within the planned period in which water levels of the tank is low.

Page 79: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

68 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5. ENVIRONMENTAL MANAGEMENT PLAN

5.1 GENERAL OVERVIEW

The purpose of this Environmental Management Plan (EMP) is to manage the anticipated on and off-

site environmental impacts due to the interventions proposed to remedy identified issues of the

dam. Therefore, it is necessary to first scan the issues that have arisen to compromise the safety and

operational efficiency of the Pimburaththewa Reservoir. The following issues and their mitigation

measures were identified and presented in the EMP.

5.2 IDENTIFICATION OF IMPACTS AND THEIR MITIGATIONS

This section summarizes the mitigation measures to be implemented for the identified

environmental impacts that can potentially occur predominantly during the construction phase of

the proposed interventions (Table 5.1). This table indicates only the ones that need mitigation

measures and those that are not listed here would not require any mitigation measures.

The DSWRPP has a strong focus on proper environmental management. Therefore, the focus of

environmental management of the project has not been limited to managing those impacts arising

due to the proposed interventions but also to improve adverse environmental conditions that will

prevail during rehabilitation work by applying proper mitigation strategies.

As a part of the EMP, appropriate institutional arrangements to implement the proposed measures

and clearances and/or approvals needed by the project prior to its implementation have been

proposed after discussing with the responsible authorities (Table 5.2). For each proposed

intervention, the EMP defines the technical content, roles and responsibilities of stakeholders,

schedule of implementation and methods of monitoring etc.

Page 80: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

69 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 5.1: Proposed mitigatory measures for the identified impacts

Issues identified as per the ToR

Issue

Inadequate capacity of the spillway canal

Erosion in spillway side ways

Deficiencies in spillway

Intervention

Removal of existing gabion structures

Excavation of spillway approach channel

Repair to the spillway side walls

Repair of spillway bed and stilling basin

Excavations for spillway construction

Removal of the existing concrete road

Construction of embankments to support the bridge deck

Construction of the bridge over the spillway

Construction of the road over the bridge and on either side of the bridge

Painting of the bridge

Slope protection

Anticipated Impacts Mitigation measure

Impact on ecological environment:

Adverse impacts on the habitats in borrow sites due to the removal of soil/ gravel. Excavated pits would be filled with rain water, creating a habitat for mosquito breeding during the rainy season. Also these pits act as a dangerous location for wild animals such as wild elephants and create accidental damage to them.

Construction materials should only obtain from licence quarries and material extraction sites. Rehabilitation/ replanting of the borrow areas with indigenous plant species after the extraction is completed. The pits should be filled and the layer of top soil is required for the growth and establishment of plants. Natural regeneration of plants mainly grasses, herbs, shrubs are expected soon after the excavation is completed.

Impact on social environment:

This will be fairly significant and time consuming construction activity in

Contractors must be get in to strict agreement to complete the work within the planned time period. The need of this work should be better convinced to the farming community through farmer leaders attended at the Block meetings, The PMU of Dam

Page 81: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

70 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

this dam. If it gets delays there can be some implications to fill the tank up

it its FSL level. Some community members access their villages through an

informal road across the spill way and there can be some disturbances to

these community members during construction period.

safety project and also the PMC of the irrigation scheme should closely monitor the process of spillway construction work.

Impacts on physical environment:

Removal and disposal of debris and excavated material

This activity involves the clearing of about 0.53 Ha of land and demolition

of the existing concrete road (469 m3) and stripping of top soil (340 m3).

The existing gabion boxes will be removed (480 m3), which will be part of

the construction material (this will partially satisfy the need of requirement

of rubble). Part of the existing riprap will be completely removed and the

surface has to be prepared for subsequent re-laying of the riprap. The

surface preparation will produce significant amounts of soil material which

need disposal.

Increasing the possibilities of erosion

The proposed construction need significant amounts of soil excavation

During site clearance activities, removal of spoil and debris must be carried out swiftly

and in well-planned manner.

Identify the sites for disposal of material cleared is needed prior to commencement of

the work.

Plants, shrubs and other vegetation cleared should not be burned on site.

Debris, spoil and other disposal materials should only be dumped at sites for which prior

approval from relevant authorities such as the LA has been obtained. Taking into account

the following

- The dumping does not impact natural drainage courses

- No endangered / rare flora is impacted by such dumping

- Should be located in non-residential areas located in the downwind side

- Located at least 100 m from the designated forest land.

- Avoid disposal on productive land.

- should be located with the consensus of the local community, in consultation

with the engineer and shall be approved by the highways department

- Minimize the construction debris by balancing the cut and fill requirements.

The contractor should avoid any spillage of spoil when transporting such materials to

the approved material dumping sites.

Debris material shall be disposed in such a manner that the tank, canals and other

existing drainage paths are not blocked (as described above)

Page 82: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

71 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

(38,043 m3 of excavation for structures and 2.971 m3 for foundations)

before construction of the spillway, spillway bed and the stilling bed.

Embankment construction and road construction involved in the bridge

construction need stripping of top soil, excavation of embankments, filling

and compaction. Such earth work will lead to soil erosion, slope erosion

and erosion of the road surfaces.

Raw water quality of surface water bodies

Raw water quality of surface water bodies can be affected due to soil

erosion. Soil particles that enter nearby water bodies, such as the tank and

canals etc., can result in temporary turbidity problems. However, the

duration of this exposure is short in duration and hence adverse impacts

anticipated would be not be significant.

Hindrance to vehicular movements, damage to the crest road surface

due to movement of heavy vehicles, temporary storage of earth along

the crest road and elsewhere

Drainage paths associated with the dam and other irrigation structures should be

improved / erected to drain rain water properly.

Silt traps will be constructed to avoid siltation into the water ways, the tank and canals,

where necessary.

To avoid siltation, drainage paths should not be directed to the tank and irrigation canals

and they should be separated from these water bodies

Bund Embankment slopes, slopes of cuts, etc. shall not be unduly exposed to erosive

forces. These exposed slopes shall be graded and covered by grass or other suitable

materials per the specifications.

All fills, back fills and slopes should be compacted immediately to reach the specified

degree of compaction and establishment of proper mulch.

Work that lead to heavy erosion shall be avoided during the raining season. If such

activities need to be continued during rainy season prior approval must be obtained

from the Engineer by submitting a proposal on actions that will be undertaken by the

contractor to prevent erosion.

The work, permanent or temporary shall consist of measures as per design or as directed

by the engineer to control soil erosion, sedimentation and water pollution to the

satisfaction of the engineer. Typical measures include the use of berms, dikes sediment

basins, fiber mats, mulches, grasses, slope drains and other devices. All sedimentation

and pollution control works and maintenance thereof are deemed, as incidental to the

earthwork or other items of work and no separate payment will be made for their

implementation.

The excavation, earthwork transportation, piling of earth, removal of spoil and debris,

removal of the existing riprap and piling of rubble along the crest road should be planned

Page 83: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

72 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

The earthwork involved in the construction work is large (41,000 m3).

Borrow material once brought to the site (7,915 m3) has to be unloaded

and stockpiled for subsequent use. This might block the existing run on and

off paths which may create erosion problems elsewhere.

Material transport (7,915 m3 of earth; approx. 5,000 m3 of concrete) may

result in congestion of local roads. There are dwelling units along haulage

routes and elevated levels of traffic matter can become a minor temporary

adverse impact during the construction period. Movement of heavy

vehicles will damage the crest road and access roads in the vicinity.

Noise and vibration

Large amounts of earth work (more than 41,000 m3 of earth excavation,

demolition of the existing road surface (468 m3), stripping of the top soil

(340 m3) and most of the other activities will generate noise. Compacting

large areas and large amounts of concrete will generate significant

amounts of noise. Much of the proposed work will be carried out using

machinery. However, small machinery will be used for excavating and

rubble and earth transport. Noise and vibration is expected to be

significantly high due to the large-scale nature of construction.

carefully. One half along the road can be used for piling of earth and rubble.

Vehicle movement along the crest road should be restricted. Axial loads of the vehicles

travelling along the crest road should be limited (based on the bearing capacity of the

bund).

Vehicular movements along the local roads should be planned based on a proper traffic

study. Proper signage should be erected for safety.

Noise from vehicles, machinery and equipment

Hydraulically driven machinery is preferred over Pneumatic machinery to minimize vibrations

Noise generating work should be limited to day time (6:00 AM to 6:00 PM). No work that

generates excessive noise should be carried out during night hours where in close

proximity (from 6:00 PM to 6:00 AM on the following day).

All equipment and machinery should be operated at noise levels that do not exceed the

permissible level of 75 dB (during construction) for the day time. For all construction

activities undertaken during the night time, it is necessary to maintain the noise level at

below 50 dB as per the Central Environmental Authority (CEA) noise control regulations

All equipment should be in good serviced condition. Regular maintenance of all

construction vehicles and machinery to meet noise control regulations stipulated by the

CEA in 1996 (Gazette Extra Ordinary, No 924/12) must be conducted for

vehicles/machinery that will be used in construction on site and for transport.

Ideally noise generating work should not be carried out during public holidays and

religious days. Special care should be taken as there is a temple nearby.

Labor gangs should be warned to work with minimum noise. Strict labor supervision

should be undertaken in this respect. Number of night time resident laborers should be

Page 84: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

73 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Dust generation

Large amounts of earth work (more than 41,000 m3 of earth excavation,

demolition of the existing road surface (468 m3), stripping of the top soil

(340 m3) and most of the other activities would produce airborne dust,

which are temporary and limited to short durations and will be restricted

to a small area. Therefore, air pollution due to the proposed work can be

considered not significant.

minimized.

Vehicular noise pollution at residential / sensitive receptors

Idling of temporary trucks or other equipment should not be permitted during periods

of loading / unloading or when they are not in active use. The practice must be ensured

especially near residential / commercial / sensitive areas.

Stationary construction equipment will be kept at least 500m away from sensitive

receptors, where possible. These include places of worship and households.

All possible and practical measures to control noise emissions during drilling shall be

employed.

Contractor shall submit the list of high noise/vibration generating machinery &

equipment to the engineer for approval.

Servicing of all construction vehicles and machinery must be done regularly and during

routine servicing operations, the effectiveness of exhaust silencers will be checked and

if found defective will be replaced.

Maintenance of vehicles, equipment and machinery shall be regular and up to the

satisfaction of the Engineer to keep noise levels at the minimum.

All construction materials such as sand, metal, lime, bricks etc. should be transported

under cover to the site and stored under cover at the sight. Plastic sheeting (of about 6

mm minimum thickness) can be used and held in place with weights, such as old tires or

cinder blocks, with the edges of the sheeting buried, or by the use of other anchoring

systems. This will minimize the levels of airborne dust.

Mud patches caused by material transporting vehicles in the access road should be

immediately cleaned.

Continual water sprinkling should be carried out in the work and fill areas and the access

road if dust stir is observed. Water sprinkling should be done more frequently on days

Page 85: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

74 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Pollution of Soil and Water via Fuel and Lubricants

The earthwork, large amounts of concrete work, and erection of the bridge

need a large fleet of heavy vehicles and heavy machinery. Activities such as

operation of construction vehicles, parking areas, fuel/lubricants spills

storage sites, machinery and equipment maintenance and refueling will

generate pollutants that have the potential to pollute soil and water.

Construction and removal of coffer dams

Transport of sheet piles, driving and removing of the sheet piles cause

numerous impacts. Noise and dust can result from transportation

activities. Noise and vibration due to pile driving and removing can cause

disturbance to neighboring community and the wildlife.

Sheet piles should be able to cutoff water movements across the coffer

dam for facilitating the construction activities.

that are dry and windy (at least four time’s day) as the levels of dust can be elevated

during dry periods.

Dust masks should be provided to the laborers for the use at required times.

All construction vehicle parking location, fuel/lubricants storage sites, vehicle, machinery and equipment maintenance and refueling sites shall be located away from the reservoir, at least 200 m away, and irrigation canal/ponds.

All vehicle/machinery and equipment operation, maintenance and refueling will be carried out in such a fashion that spillage of fuels and lubricants does not contaminate the ground.

Collect, store and dispose oily wastes to the pre-identified disposal sites approved by the Engineer. All spills and collected petroleum products will be disposed of in accordance with standards set by the CEA/MoE, certified by the Engineer.

Transport of sheet piles, conveyance of machinery etc. will cause impacts due to

transportation as described above (noise, dust, impacts related to parking, congestion,

damage of the bund road, oil and grease spills etc.). Mitigation of such impacts are

needed.

Sheet pile driving for the coffer dams involves generation of high levels of noise and

vibration. Therefore, construction should proceed with caution and with least damage

to adjacent structures and minimum disturbance to the community and wildlife.

Driving and removing sheet piles will temporarily increase turbidity and will cause

disturbance to the bottom sediments. However, this will be temporary. No mitigation is

required other than following good construction practices.

Construction and subsequent removal of the cofferdam must be planned and executed

with the same degree of care as its installation, on a stage by stage basis as per the

approved Method statement by the engineer.

Page 86: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

75 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Health and sanitation of worker’s camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

Safety requires that every cofferdam and every part thereof shall be of suitable design

and construction, of suitable and sound materials and of Sufficient strength and capacity

for the purpose for which it is used.

Thus all material used will be pre assessed by the engineer prior to use and cleared in

writing as suitable for the purpose.

As the effect of the removal on the permanent structure must also be considered. For

this reason, it may be advisable that sheet piles extending below the permanent

structure are cut off and left in place, since their removal may damage the foundation

soils adjacent to the structure.

Stringent supervision of respective loads on coffer dams at operation should be done in

order to avoid accidents and ensure worker safety

(It is assumed that construction of the coffer dam would be done only after a thorough

hydrological and geological study. This should aim at prevention accidental damage of

the coffer dam structure due to predictable water level fluctuations and the bottom

geology would be capable enough to support the sheet piles in withstanding hydraulic

pressures.)

IT is very important that the construction is carried out during the dry season, thereby

ensuring that there is no spill take place during the construction. It has to ensure that

any excess water be released only through the sluices. If there is rains during the

construction period, it is very important to control the water level continuously to

ensure that there is no need for spilling of excess water from the reservoir. Water level

raw down to an appropriate level prior to construction is recommended.

The mitigation measures and general conditions are described in Section 5.5 (Operation

of labour camps).

Page 87: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

76 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Management of waste (other than construction and excavated

material) and wastewater

Significant quantities of construction waste (e.g., during stripping of top

soil) are expected. In contrast, food items even in small quantities may

attract stray animals. However, the overall impact is very low.

Safety of workers at work

The earthwork involved in the construction work is large (41,000 m3).

Borrow material once brought to the site (7,915 m3) has to be unloaded

and stockpiled for subsequent use. The prestressed concrete sections have

to be unloaded, and subsequently handled carefully to erect the bridge.

These activities pose a severe hazard and potential to cause physical injury

to workers during moving heavy loads downhill/uphill.

Construction waste shall be collected regularly and disposed of periodically in an environmentally safe and nuisance free manner.

Wastewater will be disposed, by way of a pit latrine/soakage arrangement. This measure

too will be common and valid for the entire construction period.

The mitigation measures and general conditions are described in Section 5.4 (Safety at

work)

Issue

Damage in the rip rap in some areas

Intervention

Placing rip rap

Page 88: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

77 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Anticipated Impacts Mitigation measure

Impact on ecological environment:

Removal of vegetation, mainly the herbs and shrubs close to the water level, disturbances to the habitats due to the removal of vegetation. Significant impact are not envisage during the construction.

Site specific mitigatory measures are not required. Once the construction of rip rap is completed natural regeneration of plants, mainly the grasses and herbs will take place.

Impact on social environment:

If rip rap rehabilitation cannot be completed within the water low period

in the tank there may be need to lowering the water level or to postpone

the woRk to the next water low period of the tank

The contractors will be encouraged to complete the work during water low period of the

tank and also continues monitoring of the contractors' progress on completion of rip rap

rehabilitation within the planned period of time.

Impacts on physical environment:

Increasing the possibilities of erosion of the U/S slopes

Exposed areas of the bund are susceptible to erosion.

Hindrance to surface runoff, hindrance to vehicular movements during

temporary storage of material along the crest road and elsewhere

Borrow material once brought to the site has to be unloaded and stockpiled

for subsequent use. This might block the existing run on and off paths

which may create erosion problems elsewhere.

The quantity to be handled seems to be large hence the impact may be

relatively significant (exact quantity to be determined)

Raw water quality of surface water bodies

Runoff through material borrow areas and unloading sites could lead to

wash off of soil particles to nearby water bodies such as canals, tanks

streams etc. resulting in temporary turbidity problems. However, the

quantity to be handled seems to be very low, hence adverse impacts

anticipated would be insignificant.

There will be 3,575 m3 of rubble removed from the existing riprap, which will be piled

along the crest road. In addition, 3,050 m3 of rubble is needed for the construction of

the rip rap. In addition to the more than 6,000 m3 of rubble, 1,650 m3 of gravel and 970

m3 of well-graded aggregate are required for the base construction of the rip rap.

Debris material shall be disposed in such a manner that the tank, canals and other

existing drainage paths are not blocked (as described above)

Drainage paths associated with the dam and other irrigation structures should be

improved / erected to drain rain water properly.

Silt traps will be constructed to avoid siltation into the water ways, the tank and canals,

where necessary.

To avoid siltation, drainage paths should not be directed to the tank and irrigation canals

and they should be separated from these water bodies

Bund Embankment slopes, slopes of cuts, etc. shall not be unduly exposed to erosive

forces. These exposed slopes shall be graded and covered by grass or other suitable

materials per the specifications.

All fills, back fills and slopes should be compacted immediately to reach the specified

Page 89: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

78 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Hindrance to vehicular movements, damage to the crest road surface

due to temporary storage of rubble among the crest road and

elsewhere

Material transport may result in air pollution through giving rise to

elevated levels of airborne dust. There are dwelling units along haulage

routes and elevated levels of airborne particulate matter can become a

minor temporary adverse impact during the construction period.

Generation of noise, vibration and dust affecting the social and

biological environment

Noise and vibration can occur during compaction of the aggregate layer

and related activities. Activities that would produce airborne dust are

temporary and limited to short durations and will be restricted to a small

area.

Pollution of Soil and Water via Fuel and Lubricants

Activities such as operation of construction vehicles, parking areas, fuel/lubricants spills storage sites, machinery and equipment maintenance and refueling will generate pollutants that have the potential to pollute soil and water.

degree of compaction and establishment of proper mulch.

Work that lead to heavy erosion shall be avoided during the raining season. If such

activities need to be continued during rainy season prior approval must be obtained

from the Engineer by submitting a proposal on actions that will be undertaken by the

contractor to prevent erosion.

The work, permanent or temporary shall consist of measures as per design or as directed

by the engineer to control soil erosion, sedimentation and water pollution to the

satisfaction of the engineer. Typical measures include the use of berms, dikes sediment

basins, fiber mats, mulches, grasses, slope drains and other devices. All sedimentation

and pollution control works and maintenance thereof are deemed, as incidental to the

earthwork or other items of work and no separate payment will be made for their

implementation.

The material transportation, and storage of this material should be planned carefully.

One half along the road can be used for piling the rubble removed from the existing rip

rap. Other material should be stored appropriately, avoiding any erosion of stored earth

and gravel, not obstructing drainage pathways etc.

The work can proceed phase by phase, each phase restricted to about 50-75 m. The

surface of the slope can be prepared for subsequent laying of the new rip rap without

delay, using the removed rubble and replenishing new material as needed. If such a

procedure is followed, the need for large amounts of handling rubble at one occasion

can be avoided, thus not requiring large storage areas for piling material, especially along

the crest road.

Noise from vehicles, machinery and equipment

Hydraulically driven machinery is preferred over Pneumatic machinery to minimize vibrations

Noise generating work should be limited to day time (6:00 AM to 6:00 PM). No work that

generates excessive noise should be carried out during night hours where in close

Page 90: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

79 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

proximity (from 6:00 PM to 6:00 AM on the following day).

All equipment and machinery should be operated at noise levels that do not exceed the

permissible level of 75 dB (during construction) for the day time. For all construction

activities undertaken during the night time, it is necessary to maintain the noise level at

below 50 dB as per the Central Environmental Authority (CEA) noise control regulations

All equipment should be in good serviced condition. Regular maintenance of all

construction vehicles and machinery to meet noise control regulations stipulated by the

CEA in 1996 (Gazette Extra Ordinary, No 924/12) must be conducted for

vehicles/machinery that will be used in construction on site and for transport.

Ideally noise generating work should not be carried out during public holidays and

religious days. Special care should be taken as there is a temple nearby.

Labor gangs should be warned to work with minimum noise. Strict labor supervision

should be undertaken in this respect. Number of night time resident laborers should be

minimized.

Vehicular noise pollution at residential / sensitive receptors

Idling of temporary trucks or other equipment should not be permitted during periods

of loading / unloading or when they are not in active use. The practice must be ensured

especially near residential / commercial / sensitive areas.

Stationary construction equipment will be kept at least 500m away from sensitive

receptors, where possible. These include places of worship and households.

All possible and practical measures to control noise emissions during drilling shall be

employed.

Contractor shall submit the list of high noise/vibration generating machinery &

equipment to the engineer for approval.

Servicing of all construction vehicles and machinery must be done regularly and during

routine servicing operations, the effectiveness of exhaust silencers will be checked and

Page 91: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

80 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

if found defective will be replaced.

Maintenance of vehicles, equipment and machinery shall be regular and up to the

satisfaction of the Engineer to keep noise levels at the minimum.

Dust Control

All construction materials such as sand, metal, lime, bricks etc. should be transported

under cover to the site and stored under cover at the sight. Plastic sheeting (of about 6

mm minimum thickness) can be used and held in place with weights, such as old tires or

cinder blocks, with the edges of the sheeting buried, or by the use of other anchoring

systems. This will minimize the levels of airborne dust.

Mud patches caused by material transporting vehicles in the access road should be

immediately cleaned.

Continual water sprinkling should be carried out in the work and fill areas and the access

road if dust stir is observed. Water sprinkling should be done more frequently on days

that are dry and windy (at least four time’s day) as the levels of dust can be elevated

during dry periods.

Dust masks should be provided to the laborers for the use at required times.

All construction vehicle parking location, fuel/lubricants storage sites, vehicle, machinery and equipment maintenance and refueling sites shall be located away from the reservoir, at least 200 m away, and irrigation canal/ponds.

All vehicle/machinery and equipment operation, maintenance and refueling will be carried out in such a fashion that spillage of fuels and lubricants does not contaminate the ground.

Collect, store and dispose oily wastes to the pre-identified disposal sites approved by the Engineer. All spills and collected petroleum products will be disposed of in accordance with standards set by the CEA/MoE, certified by the Engineer.

Construction waste shall be collected regularly and disposed of periodically in an

Page 92: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

81 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Management of waste (other than construction and excavated

material) and wastewater

No significant quantities of construction waste are expected. In contrast,

food items even in small quantities may attract stray animals. However,

the overall impact is very low.

Health and sanitation of worker’s camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Safety of workers at work

Placing the rubble for the riprap will be done manually. Placing and

moving rubble from the bund crest towards the bund slopes involve

extensive amount of manual labour work. These activities pose a severe

hazard and potential to cause physical injury to workers during moving

heavy loads downhill/uphill.

environmentally safe and nuisance free manner.

Wastewater will be disposed, by way of a pit latrine/soakage arrangement. This measure

too will be common and valid for the entire construction period.

The mitigation measures and general conditions are described in Section 5.5 (Operation

of labour camps).

The mitigation measures and general conditions are described in Section 5.4 (Safety at

work)

Work should proceed phase by phase, each phase involving the work of about 50-75 m. This will prevent huge amount of rubble handling and storing along the crest, minimizing the safety issues. Laborers should be instructed to coordinate properly while carrying heavy loads. Any injuries should be attend to complying with emergency procedures.

Page 93: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

82 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Issues identified during the initial site visit

Issue

Seepage areas along the downstream toes

Intervention

Construction of Toe road and toe drain

Construction of V-notches

Anticipated Impacts Mitigation measure

Impacts on ecological environment:

Removal of vegetation, disturbances to the habitats

The vegetation removal will take place during the construction of toe road and toe filter. Fauna found in the toe area of the bund would move to other habitats during the construction of the toe road. So other habitats in the vicinity of tank should not be disturbed. Habitat or species specific mitigation measures are not required. To increase the vegetation cover it is recommended to plant indigenous plant species in the project affected area once the construction is completed.

Impacts on social environment:

No impacts are expected because there is adequate land area that can be

used to establish the toe road and other infrastructure facilities required

in the downstream of the Dam

No specific mitigation measures are required.

Impacts on physical environment:

Need to dispose debris and excavated material away from the site

Construction of the toe filter and drain include removing the existing toe

drain, excavation and removal of unsuitable soil material, bed formation

and stripping of soil. Further, construction of the toe road also involves

stripping of top soil and exaction of soil. These are significant amount that

has to be disposed properly (quantities of these material have to be

determined after designs are completed).

During site clearance activities, removal of vegetation and debris must be carried out

swiftly and in well-planned manner.

Identify the sites for disposal of material cleared is needed prior to commencement of

the work.

Plants, shrubs and other vegetation cleared should not be burned on site.

Spoil and other disposal materials should only be dumped at sites for which prior

approval from relevant authorities such as the LA has been obtained. Taking into account

the following

Page 94: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

83 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Increasing the possibilities of erosion of the toe areas in the D/S

Construction of the toe drain, filter and the tow road involve stripping of

top soil and loose rubble in the filter. Such exposed areas of the bund toe

area are susceptible to erosion.

Hindrance to surface runoff

Construction of the toe filter and drain include removing the existing toe

drain, excavation and removal of unsuitable soil material, bed formation

and stripping of soil. Construction of the toe road also involves stripping of

top soil and exaction of soil. These will pile up at the construction site,

which will hinder surface drainage.

Construction of the toe filter and drain need sand, graded gravel, and

rubble. Toe road construction need earth and gravel. These materials once

brought to the site have to be unloaded and stockpiled for subsequent use.

This might block the existing run on and off paths which may create erosion

problems elsewhere (quantities of these material have to be determined

after designs are completed).

The quantity to be handled seems to be fairly large hence the impact may

be moderately significant.

Raw water quality of surface water bodies

Runoff through material borrow areas and unloading sites could lead to

wash off of soil particles to nearby water bodies such as canals, tanks

streams etc. resulting in temporary turbidity problems. However, the

quantity to be handled seems to be very low, hence adverse impacts

anticipated would be insignificant.

Increase in vehicular traffic during transport of construction materials

Material transport may result in air pollution through giving rise to

elevated levels of airborne dust. There are dwelling units along haulage

- The dumping does not impact natural drainage courses

- No endangered / rare flora is impacted by such dumping

- Should be located in non-residential areas located in the downwind side

- Located at least 100 m from the designated forest land.

- Avoid disposal on productive land.

- should be located with the consensus of the local community, in consultation

with the engineer and shall be approved by the highways department

- Minimize the construction debris by balancing the cut and fill requirements.

The contractor should avoid any spillage of spoil when transporting such

materials to the approved material dumping sites.

Debris material shall be disposed in such a manner that the tank, canals and other

existing drainage paths are not blocked (as described above)

Drainage paths associated with the dam and other irrigation structures should be

improved / erected to drain rain water properly.

Silt traps will be constructed to avoid siltation into the water ways, the tank and canals,

where necessary.

To avoid siltation, drainage paths should not be directed to the tank and irrigation canals

and they should be separated from these water bodies

Bund Embankment slopes, slopes of cuts, etc. shall not be unduly exposed to erosive

forces. These exposed slopes shall be graded and covered by grass or other suitable

materials per the specifications.

All fills, back fills and slopes should be compacted immediately to reach the specified

degree of compaction and establishment of proper mulch.

Work that lead to heavy erosion shall be avoided during the raining season. If such

activities need to be continued during rainy season prior approval must be obtained

from the Engineer by submitting a proposal on actions that will be undertaken by the

contractor to prevent erosion.

Page 95: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

84 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

routes and elevated levels of airborne particulate matter can become a

minor temporary adverse impact during the construction period.

Health and sanitation of workers’ camps

This impact is common for all the activities. The temporary camps, if not

managed properly, may create an unhealthy environment causing health

hazards to both workers and nearby residents. However, the number of

workers to be employed seems not many. Hence the impact is insignificant.

Management of waste (other than construction and excavated

material) and wastewater

No significant quantities of construction waste (other than the excavated

material as described above) are expected. In contrast, food items even in

small quantities may attract stray animals. However, the overall impact is

very low.

Generation of noise, vibration and dust affecting the social and

biological environment

Noise and vibration can occur during compaction of the gavel bedding for

the toe road, loading berm, drains etc. and compacting the aggregate

layers. Activities that would produce airborne dust are temporary and

limited to short durations and will be restricted to a small area.

Pollution of Soil and Water via Fuel and Lubricants

Activities such as operation of construction vehicles, parking areas, fuel/lubricants spills storage sites, machinery and equipment maintenance and refueling will generate pollutants that have the potential to pollute soil and water.

Safety of workers at work

The work, permanent or temporary shall consist of measures as per design or as directed

by the engineer to control soil erosion, sedimentation and water pollution to the

satisfaction of the engineer. Typical measures include the use of berms, dikes sediment

basins, fiber mats, mulches, grasses, slope drains and other devices. All sedimentation

and pollution control works and maintenance thereof are deemed, as incidental to the

earthwork or other items of work and no separate payment will be made for their

implementation.

Noise from vehicles, machinery and equipment

Hydraulically driven machinery is preferred over Pneumatic machinery to minimize vibrations

Noise generating work should be limited to day time (6:00 AM to 6:00 PM). No work that

generates excessive noise should be carried out during night hours where in close

proximity (from 6:00 PM to 6:00 AM on the following day).

All equipment and machinery should be operated at noise levels that do not exceed the

permissible level of 75 dB (during construction) for the day time. For all construction

activities undertaken during the night time, it is necessary to maintain the noise level at

below 50 dB as per the Central Environmental Authority (CEA) noise control regulations

All equipment should be in good serviced condition. Regular maintenance of all

construction vehicles and machinery to meet noise control regulations stipulated by the

CEA in 1996 (Gazette Extra Ordinary, No 924/12) must be conducted for

vehicles/machinery that will be used in construction on site and for transport.

Ideally noise generating work should not be carried out during public holidays and

religious days. Special care should be taken as there is a temple nearby.

Labor gangs should be warned to work with minimum noise. Strict labor supervision

should be undertaken in this respect. Number of night time resident laborers should be

minimized.

Page 96: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

85 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Placing the rubble for the toe filter will be done manually. Placing and

moving rubble towards the bund slopes involve extensive amount of

manual labour work. These activities pose a severe hazard and potential to

cause physical injury to workers during moving heavy loads

downhill/uphill.

Installation of the V-notches and three piezometers will have very minor

environmental impacts.

Vehicular noise pollution at residential / sensitive receptors

Idling of temporary trucks or other equipment should not be permitted during periods

of loading / unloading or when they are not in active use. The practice must be ensured

especially near residential / commercial / sensitive areas.

Stationary construction equipment will be kept at least 500m away from sensitive

receptors, where possible. These include places of worship and households.

All possible and practical measures to control noise emissions during drilling shall be

employed.

Contractor shall submit the list of high noise/vibration generating machinery &

equipment to the engineer for approval.

Servicing of all construction vehicles and machinery must be done regularly and during

routine servicing operations, the effectiveness of exhaust silencers will be checked and

if found defective will be replaced.

Maintenance of vehicles, equipment and machinery shall be regular and up to the

satisfaction of the Engineer to keep noise levels at the minimum.

Dust Control

All construction materials such as sand, metal, lime, bricks etc. should be transported

under cover to the site and stored under cover at the sight. Plastic sheeting (of about 6

mm minimum thickness) can be used and held in place with weights, such as old tires or

cinder blocks, with the edges of the sheeting buried, or by the use of other anchoring

systems. This will minimize the levels of airborne dust.

Mud patches caused by material transporting vehicles in the access road should be

immediately cleaned.

Continual water sprinkling should be carried out in the work and fill areas and the access

road if dust stir is observed. Water sprinkling should be done more frequently on days

that are dry and windy (at least four time’s day) as the levels of dust can be elevated

Page 97: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

86 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

during dry periods.

Dust masks should be provided to the laborers for the use at required times.

All construction vehicle parking location, fuel/lubricants storage sites, vehicle, machinery and equipment maintenance and refueling sites shall be located away from the reservoir, at least 200 m away, and irrigation canal/ponds.

All vehicle/machinery and equipment operation, maintenance and refueling will be carried out in such a fashion that spillage of fuels and lubricants does not contaminate the ground.

Collect, store and dispose oily wastes to the pre-identified disposal sites approved by the Engineer. All spills and collected petroleum products will be disposed of in accordance with standards set by the CEA/MoE, certified by the Engineer.

The mitigation measures and general conditions are described in Section 5.5 (Operation

of labour camps).

Construction waste shall be collected regularly and disposed of periodically in an environmentally safe and nuisance free manner.

Wastewater will be disposed, by way of a pit latrine/soakage arrangement. This measure

too will be common and valid for the entire construction period.

The mitigation measures and general conditions are described in Section 5.4 (Safety at

work)

Work should proceed phase by phase, each phase involving the work of about 100 m. This will prevent huge amount of rubble handling and storing along the sloping areas of the toe of the bund, minimizing the safety issues. Laborers should be instructed to coordinate properly while carrying heavy loads. Any injuries should be attended to

Page 98: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

87 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

complying with emergency procedures.

No mitigation needed.

Page 99: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

88 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5.3 PROCUREMENT OF MATERIAL NEEDED FOR IMPLEMENTING THE PROPOSED

INTERVENTIONS

5.3.1 Material Sourcing

The proposed interventions for Pimburaththewa Reservoir need significant amounts of ruble (about

6,500 m3), gravel and earth (about 4,500 m3) and aggregates (about 1,000 m3) sand (80 m3).

Therefore, significant impacts on geological resources is anticipated at quarry sites and borrow

areas, and therefore the contractors should ensure that sand, aggregates and other quarry material

is sourced from licensed sources.

The contractor is required to maintain the necessary licenses and environmental clearances for all

borrow and quarry material they are sourcing to obtain soil , fine aggregate and coarse aggregate.

Sourcing of any material from protected areas and/or designated natural areas are strictly

prohibited.

If the contractor uses non-commercial burrow/quarry sites, the sites should be remediated

accordingly once material sourcing has been completed. The Project Supervision Engineer will

require maintaining the numbers and relevant details of all necessary licenses etc. and report of their

status accordingly.

5.3.2 Management of Borrow Sites

- Any earth excavated within the project area arising from construction works may be used as fill

material if properties of the soil are suitable for such filling. At Pimburaththewa, the excavated

soil (about 1,250 m3) can be used for filling if the Engineer finds approves its use.

- The material supplier and/or the contractor shall comply with the environmental

requirements/guidelines issued by the CEA and the respective local authorities with respect of

locating borrow areas and with regard to all operations related to excavation and transportation

of earth from such sites.

- The material supplier and/or the contractor can also find suitable soil/earth materials from

currently operated licensed burrow pits in the surrounding area, subject to approval of the

Engineer

- No borrow-sites be used (current approved) or newly established within areas protected under

FFPO and FO, especially within the Maduru Oya National Park.

- Borrow areas shall not be opened without having a valid mining license from the GSMB. The

location, depth of excavation and the extent of the pit or open cut area shall be as approved by

the engineer.

- All borrow pits/areas should be rehabilitated at the end of their use by the contractor in

accordance with the requirements/guidelines issued by the CEA and the respective local

authority.

- Establishment of borrow pits/areas and its operational activities shall not cause any adverse

impact to the near-by properties. Also shall not be a danger of health hazard to the people.

Contractor shall take all steps necessary to ensure the stability of slopes including those related to

temporary works and burrow pits.

Page 100: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

89 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5.3.3 Quarry Operations and Management of Quarry Sites

- Utilizing the existing quarry sites available in the project influential area as much as possible

which are approved by GSMB with valid EPL and Industrial Mining Licenses;

- If new quarries are to be opened, prior approval should be obtained from GSMB, CEA and

local authorities such as Pradeshiya Sabha.

- Selected quarry sites should have proper safety measures such as warnings, safety nets etc.,

and third party insurance cover to protect external parties that may be affected due to

blasting.

- Quarry sites should not be established within protected sites identified under the FFPO and

FO

- It is recommended not to seek material from quarries that have ongoing disputes with

community.

- The maintenance and rehabilitation of the access roads in the event of damage by the

contractors operations shall be a responsibility of the contractor.

Copies of all relevant licenses should be maintained by the contractor for review and documentation

by the Engineer.

5.4 SAFETY ISSUES

Table 5.2: General safety issues that need to be addressed

Public and Worker

Safety

The construction site should be barricaded at all time in a day with adequate

marking, safety tape, flags, reflectors etc. for safety of individuals using the

site daily basis. (Items such as parking cones, lights, tubular markers, orange

and white strips and barricades of a luminous nature for night visibility shall

be procured where deemed necessary).

At all times, the Contractor shall provide safe and convenient passage for

vehicles, pedestrians and livestock. Work that affects the use of existing

accesses shall not be undertaken without providing adequate provisions to the

prior satisfaction of the Engineer.

The construction site should be clearly demarcated by the above means and

restriction of access to public to the site will help the safety of public.

Safety signboards should be displayed at all necessary locations.

The contractor should obtain a Third Party Insurance to compensate any

damages, injuries caused to the public or laborers during the construction

period.

All construction vehicles should be operated by experienced and trained

operators under supervision.

Basic onsite safety training should be conducted for all laborers during the

EMP training prior to the start of the construction activities.

Page 101: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

90 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

All digging and installation work should be completed in one go, if this task is

not accomplished the area should be isolated using luminous safety tape and

barricading structures surrounding the whole area.

Trenches should be progressively rehabilitated once work is completed.

Material loading and unloading should be done in an area, well away from

traffic and barricaded

Construction wastes should be removed within 24 hours from the site to

ensure public safety.

Safety Gear for

Labors

Protective footwear and protective goggles should be provided to all workers

employed on mixing of materials like cement, concrete etc.

Welder's protective eye-shields shall be provided to workers who are engaged

in welding works.

Earplugs shall be provided to workers exposed to loud noise, and workers

working in crushing, compaction, or concrete mixing operation.

The contractor shall supply all necessary safety appliances such as safety

goggles, helmets, safety belts, ear plugs, mask etc. to workers and staffs.

In addition, the contractor shall maintained in stock at the site office, gloves,

ear muffs, goggles, dust masks, safety harness and any other equipment

considered necessary.

A safety inspection checklist should be prepared taking into consideration

what the workers are supposed to be wearing and monitored on a monthly

basis and recorded.

Prevention of

accidents

Prevention of accidents involving human beings, animals or vehicles falling or

accidents due to open trenches/manholes during construction period. This

needs to be ensured with proper barricading, signage boards and lighting etc.

A readily available first aid unit including an adequate supply of sterilized

dressing materials and appliances should be available at the site office at all

times

Availability of suitable transport at all times to take injured or sick person(s) to

the nearest hospital should also be insured.

Names and contact information for emergency services such as Ambulance

services, hospitals, police and the fire brigade should be prepared as a sign

board and displayed at the work site.

5.5 OPERATION OF LABOUR CAMPS

The following aspects are important to follow when constructing of labor camps

The location, layout and basic facility provision of labor camp must be submitted to Engineer

prior to their construction.

The construction will commence only upon the written approval of the Engineer.

The contractor shall maintain necessary living accommodation and ancillary facilities in

functional and hygienic manner and as approved by the Engineer.

All temporary accommodation must be constructed and maintained in such a fashion that

uncontaminated water is available for drinking, cooking and washing. The sewage system for

Page 102: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

91 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

the camp must be planned and implemented with concurrence from the Local Public Health

Officer (PHI)

Adequate health care is to be provided for the work force. The layout of the construction

camp and details of the facilities provided should be prepared and shall be approved by the

engineer.

Labor camp sites after use should be cleared and the site should be reinstated to previous

condition at the close of the construction work.

The following aspects have to be looked into when operating labor camps.

The Contractor shall construct and maintain all labor accommodation in such a fashion that

uncontaminated water is available for drinking, cooking and washing.

Supply of sufficient quantity of potable water (as per SLS) in every workplace/labor camp site

at suitable and easily accessible places and regular maintenance of such facilities.

The sewage system for the camp are designed, built and operated in such a fashion that no

health hazards occurs and no pollution to the air, ground water or adjacent water courses

take place. Ensure adequate water supply is to be provided in all toilets and urinals.

The contractor shall provide garbage bins in the camps and ensure that these are regularly

emptied and disposed of in a hygienic manner

5.6 IMPLEMENTATION PROCEDURES OF PROPOSED MITIGATION

The specific mitigation measures given in the Table 5.1 should be implemented by the contractor

when each and every intervention is done. In addition to the specific measures, the contractor must

adhere to the civil engineering best practices as practical as possible. Most of such practices are

described in ICTAD specifications and the contractor is recommended to follow them when

appropriate.

Time of the implementation of mitigation measures should be decided by the contractor and they

should be informed to the Project Engineer in advance and his approval should be obtained. The key

performing indicators (KPIs) for every mitigation measure carried out must be worked out and

should be informed to the PM for subsequent checks and balances. Once the KPIs are accepted such

indicators should be monitored by the PM to ensure that measures are taken to minimize or avoid

environmental degradation or pollution that is very likely due to the said project.

It should be necessary that all mitigation measures mentioned in the report be implemented by the

contractor and for such implementation budgetary allocation must be set aside. It has to be done

during the bidding process and the allocation so kept must be utilized by the contractor in an

efficient manner.

Implementation responsibility: for all tasks identified below fall under the purview of the contractor.

The contractor is contractually bound to implement the activities outlined in the EMP during the

implementation of the physical works outlined in the work plan

Supervision responsibility: The Project Proponent, i.e. the project engineer, technical officers of the

respective project management units and Dam safety PMUs environmental unit will be responsible

for the monitoring of all activities and reporting on compliance of implementation as well as

Page 103: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

92 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

providing technical guidance to the contractor and staff on ensuring field level implementation is

achieved in a satisfactory manner.

5.7 INFORMATION DISCLOSURE AMONG STAKEHOLDERS

Discussions should be conducted with the residents who reside around the immediate vicinity

of the construction site; provide them with information on the project activities muster their

views for possible impact mitigation as this will also ensure a good rapport and fewer

complaints. This should be done immediately once the contractor is mobilized.

The contractor will maintain a log of any grievances/complains and actions taken to resolve

them.

A copy of the EMP should be available at all times at the project supervision office on site.

5.8 POST-CONSTRUCTION ACTIVITIES

Clearing/Closure of Construction Site/Labor Camps

Site restoration plans have to be formulated for approval by the engineer. The plan is to be

implemented by the contractor prior to demobilization. This includes borrow sites and

storage yards as well.

On completion of the works, all temporary structures will be cleared away, all rubbish cleared,

excreta or other disposal pits or trenches filled in and effectively sealed off and the site left

clean and tidy, at the contractor’s expenses, to the entire satisfaction of the engineer.

Environmental Enhancement/Landscaping

Landscape plantation, including turfing of bund walls, re-vegetation of embankments and

other slopes, edge treatment of water bodies shall be taken up as per either detailed design

or typical design guidelines given as part of the Bid Documents.

The contactor also shall remove all debris, piles of unwanted earth, spoil material, away from

the dam site and from other work places and disposed at locations designated or acceptable

to the Engineer.

Page 104: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

93 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5.9 FORMAL CLEARANCES AND APPROVAL NEEDED

Table 5.3 gives the details of the clearances and approvals for the project

Table 5.3: Formal clearances and approval needed

No Issues / Activity / Intervention needing the permit or approval

The Reasons for the Approval (Law, act or enforcements etc)

Authority from which permit or approval or Clarence is required

Prior Approval and Acts

1 National Environmental Protection and Quality Regulations under Extraordinary Gazette notification No. 1534/18 and No. 1533/16 of 2008 under NEA section 32 & 23A, 23B

Environmental Protection License (EPL) from CEA, in particular prescribed activities in gazette No. 1533/16 of 2008 (i.e., Concrete batching plants, treatment plants, sewerage networks, mechanized mining activities etc.) is required during construction period and license need to be obtained to collect, transport, store, recover, recycle or dispose waste or establish any site or facility for the disposal of any waste during the construction and operation period.

CEA and The Local Authority (Dehiattakandiya Pradeshiya Sabha)

Environmental Protection License (EPL) from CEA/ Divisional Secretariat - Dehiattakandiya for identifying waste dumping sites /Local Authority (Dehiattakandiya Pradeshiya sabha) for waste collection and to issue machinery permits

2 Mines & Minerals Act No. 33 of 1992 The Act regulates the process of approval required for exploration, mining, trading and transport of geological material (sand, earth, gravel, metal etc.)

Geological Survey and Mines Bureau Industrial Mining License (IML) from Geological Survey and Mines Bureau

Note: Refer Section 1.1.2: Environmental Assessment Requirements for further details on The World Bank Requirements, and National Environmental

Legislation framework relevant to this Project.

Page 105: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

94 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

5.10 PROCEDURES FOR DEALING WITH CHANCE FINDS

5.10.1 Chance found Flora and Fauna

The contractor will take reasonable precaution to prevent workmen or any other persons

from removing and damaging any flora (plant/vegetation) and fauna (animal) including

fishing in any water body and hunting of any animal.

If any wild animal is found near the construction site at any point of time, the contractor

will immediately upon discovery thereof acquaint the Engineer and carry out the

Engineer's instructions for dealing with the same.

The Engineer will report to the nearby Forest Department /Department of Wildlife

Conservation (range office or divisional office) and will take appropriate steps/ measures,

if required in consultation with the forest officials.

5.10.2 Chance found Archaeological Property

All fossils, coins, articles of value of antiquity, structures and other remains or things of

geological or archaeological interest discovered on the site shall be the property of the

Government and shall be dealt with as per provisions of the relevant legislation.

The contractor will take reasonable precautions to prevent his workmen or any other

persons from removing and damaging any such article or thing. He will, immediately upon

discovery thereof and before removal acquaint the Engineer of such discovery and carry

out the instructions for dealing with the same, waiting which all work shall be stopped.

The Engineer will seek direction from the Archaeological Department of Sri Lanka and

inform the project EO to follow the Chance Find Procedures set forth.

Page 106: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

95 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

6. MONITORING PLAN

6.1 ENVIRONMENTAL COMPLIANCE AND MONITORING

Environmental monitoring is required in order to make sure that the anticipated adverse impacts

are kept minimal with the implementation of mitigation measures as and when required. The

monitoring objectives are therefore focused on the mitigation of likely impacts. In addition,

compliance with the existing regulations and legislation is also guaranteed. Table 6.1 enumerates

the summary of monitoring plan (MP) required for the entire project.

The monitoring will be required to record the stakeholder complaints/concerns to the delays of the

contractors on completing the riprap rehabilitation, sluice gates repairs of the tank. The Dam safety

project’s PMU has comprehensive monitoring mechanism on the contractors progress on the

construction contract packages offered to them but specific monitoring will be required to verify the

implementation of mitigatory measures recommended in this EA report. The most required

mitigatory measure is contractors’’ performance to complete the critical work that need to be

completed during water low period of the tank.

The process of implementing the mitigatory measures and other recommendations in the EA report

will be monitored through the existing committee system of MASL. These committees include three-

tiered institutions from bottom level to upper level. The Unit Management committee (UMC) is the

lower level one and Block Management committee (BMC) is the middle level and Project

Management committee (PMC) is the upper level one. The Dam safety project and the impacts of its

implementation in the irrigation scheme can be included as new discussion item in the agenda of

the three committee meetings. These committees meet once a month in such a way to discuss the

issues and problems in the entire irrigation scheme. The Unit committee brings the issues to the

Block committee and the Block committee forwards the issues to the project committee and

therefore, it covers the discussions of the issues in the entire irrigation scheme. This system can be

used for the monitoring system of the proposed dam safety activities and the Project committee

(PMC) will be attended by the representatives of PMU of Dam safety project and contractors as

new participants.

Page 107: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

96 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Table 6.1: Summary of monitoring requirement

Specific intervention

Monitoring Parameters

Monitoring Frequency

Total Time Period Months

Responsible

Institution/ person for implementation

Responsible Key Persons for supervision

Framework of the Institutional Arrangement to incorporate the Findings of MP to Project implementation

Rehabilitation of the spillway

Provide rip rap at U/S face of the dam

Construction of toe filter and toe road

Turbidity in the working section of the tank

When such incidents occur

During the whole activity

Contractor

Project Manager or his nominee

PM to inform the contractor of the monitoring and the contractor to submit the reports as agreed;

Reports to be submitted to the Project Office (PO) and then the reports to be evaluated by the World Bank (WB) and PO for approval.

Airborne dust

(along haulage routes)

When complaints are received or dust found in dwelling units

During the whole intervention

Contractor Project Manager or his nominee

Stock piling plan

At the beginning of the intervention

During the whole intervention

Contractor Project Manager or his nominee

Page 108: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

97 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Material haulage from borrow areas

Noise levels

Vibration levels

Airborne dust levels

Presence of invasive species

When a complaint is received

When a complaint is received

When a complaint is received

One in 10 vehicles of borrow martials brought in to the site

During the material transport

During the material transport

During the material transport

During the material transport

Contractor

Contractor

Contractor

Contractor

Project Manager or his nominee

Project Manager or his nominee

Project Manager or his nominee

Project Manager or his nominee

As mentioned above

As mentioned above

As mentioned above

As mentioned above

Page 109: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

98 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

7. COST ESTIMATION FOR ENVIRONMENTAL MANAGEMENT PLAN

7.1 COST ESTIMATE OF ENVIRONMENTAL MANAGEMENT PLAN

General costs to be incurred in implementing the EMP is given in Table 7.1

Table 0.1: Cost Estimate of EMP

Issue Mitigation Details of Costing Itemized Cost

Activities such as material transport,

soil stockpiling, etc. may result in air

pollution through airborne dust. If

there are dwelling units along haulage

routes there may be a minor

temporary adverse impact during this

period.

Dust emission due to transport

operations should be controlled by wet

spraying and tarpaulin covering in

mandatory on trucks/lorries which are

used for transporting materials

particularly in built up areas.

Sprinkling of water has to be carried out

using bowsers, or tractors where there

are dwelling unit only when necessary.

Lorries and trucks should be covered

(with tarpaulin sheets) when

transporting earth and gravel.

Sprinkling of water:

- Bowser: Rs. 5,000 -6,000 per

bowser

- Tractor: Rs. 2,500 per tractor

Covering with tarpaulin sheets:

Rs. 200/m2

Health and sanitation of worker’s

camps and that of residents in the

adjoining areas:

The temporary camps if not managed

properly may create an unhealthy

environment causing health hazards

to both workers and nearby residents.

(see section 5.4)

Proper sanitation facilities should be

provided on-site for the workforce.

Ideally, this can be a pit latrine in which

the pit is located above the ground water

table. Covering the deposit (with earth or

sawdust) is necessary to prevent smells

and to discourage flies.

Costs involved in providing pit latrines

Cost in providing provisions for proper

waste management

Rs. 10,000 – 15,000

Nominal costs

Operation of borrow areas causes

Erosion and slides in borrowing areas

occurring in hillocks would lead to loss

of topsoil and vegetation loss, hence

habitat loss.

After borrowing the slope/gradient of the

area should be graded to match or blend

with the existing terrain.

Plant the area with native trees and water

regularly

The costs that may incur involve grading

of borrow pit edges

Cost of construction depends on

the scale of the borrow pit.

The cost of the rehabilitation of

the borrowing area with turfing

will be Rs. 500 per 1 m2.

Page 110: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

99 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Issue Mitigation Details of Costing Itemized Cost

Re-establishment of vegetation would

be hindered due to loss of fertile soil

Any borrow pits on the tank bed also

should be graded properly.

Replanting/ rehabilitation of

habitats (e.g. in borrow sites)

need a budget of Rs. 400,000 /ha

for replanting.

Safety of Workers and Public

(as outlined in Table 5.2)

Provision of proper safety equipment,

safety gear, taking precautions and

preventive measures etc. as outlined in

Table 5.2

Safety gear, appliances and equipment,

signage and warning signs, third party

insurance and worker liability insurance,

cost of training provided to workers

Nominal sums to be included in

the engineering estimates to be

borne by the Contractor

Closure of Construction Site/Labor

Camps

Environmental

Enhancement/Landscaping

Site restoration plans have to be

formulated for the construction site

All temporary structures shall be cleared

away, all rubbish cleared, excreta or

other disposal pits or trenches filled in

and effectively sealed off and the site left

clean and tidy.

Remove all debris, piles of unwanted

earth, spoil material and disposed at

designated locations.

Landscape plantation, including turfing

of bund walls, re-vegetation of

embankments and other slopes, etc.

Nominal sums to be included in

the engineering estimates to be

borne by the Contractor.

Nominal sums to be included in

the engineering estimates to be

borne by the Contractor.

Rs. 40/m2 for turfing

Page 111: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

100 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Major issues that need mitigation and the related costs are provided in Table 7.1. Most of the

mitigation measures are related to good construction practices and related mitigation costs for most

of the items are embedded in the Engineering Cost Items. However, if the following items are not

directly given under the Engineering Cost, the construction contractor should make necessary

provisions to undertake the relevant items and costs should be included in contractor’s rates.

Salary for officer to monitor environmental management plan implementation (as provided

in Table 6.1)

Costs for environmental monitoring for specific interventions and measuring parameters as

stipulated in project specific environmental assessment (See Table 5.1 and 6.1)

Miscellaneous fees for the organizations involving in monitoring activities.

Page 112: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

101 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

8. CONCLUSIONS AND RECOMMENDATIONS

8.1 CONCLUSIONS

The proposed interventions for the repair work of the spillway, and the approach channel together

with the bridge construction involve major construction activities. Removal of existing gabion

structures, excavation of spillway approach channel, repair to the spillway side walls, bed and the

stilling basin, excavations for spillway construction are major construction activities which will cause

moderately significant impacts. Removal of the existing concrete road, construction of

embankments to support the bridge deck, construction of the bridge over the spillway and

construction of the road over the bridge and on either side of the bridge is also interventions which

will cause moderately significant impacts.

Removal and disposal of debris and excavated material, and increasing the possibilities of erosion

can deteriorate water quality of surface water bodies. Hindrance to vehicular movements, damage

to the crest road surface due to movement of heavy vehicles, temporary storage of earth along the

crest road and elsewhere, impacts due to parking of vehicles and machinery have to be monitored

closely. Noise and vibration and dust generation also can occur due to large-scale construction using

heavy machinery.

Construction and removal of coffer dams is one of the major interventions which need careful

attention. It is assumed that construction of the coffer dam would be done only after a thorough

hydrological and geological study. This should aim at prevention accidental damage of the coffer

dam structure due to predictable water level fluctuations and the bottom geology would be capable

enough to support the sheet piles in withstanding hydraulic pressures. Also, the work has to be

carried out during the dry season only, when the water level can be controlled. Always, the water

level fluctuations (especially rising water levels) have to be monitored during and after rainfalls. If

needed, the sluice gates can be opened sufficiently to draw down the water levels appropriately.

The Pimbureththewa tank project area can be categorized mainly as having human-influenced-

habitats. This is amply reflected by the habitats and species assemblages recorded during the survey.

The areas identified for project interventions do not contain any critical habitats or restricted or

endangered species. The main impact anticipated in these habitats includes the habitat degradation,

fragmentation and loss of habitat. There will not be a total loss of habitat for any animal or plant

species in the project area. Therefore, habitat or species specific mitigatory measures are not

required. No specific migratory paths or routes were identified within the project area. The proposed

development will not have an impact on migratory birds. The proposed project will not impair animal

movements in the project area, and it will not have a significant impact on any known critical animal

migration paths.

The rip rap and spillway rehabilitation in the Dam are the sensitive work items from the social impact

point of view. Low water levels will be a requirement to complete these activities. The water level in

the tank goes down for short period just after the Yala harvesting. This is the period to be used for

the completion of these sensitive construction activities proposed.

Page 113: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

102 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

If the contractors fail to complete the sensitive work items during the short dry spell in which water

level is naturally low there will be negative implications on seasonal agriculture in the scheme.

Therefore, this crucial issue should be considered as most priority activity to be monitored by PMU

and also RPM's office in System C through its existing joint management committee system ( UMCs,

BMC and PMC) where farmer representatives and agency officers sit together to discuss the

problems in their irrigation scheme in every month.

Other interventions are accepted and the project can go ahead without any specific environmental

mitigation measures. Nevertheless, best practices listed on the EMP should be practiced as practical

as possible. ICTAD specifications on civil engineering practices must be followed as and when

applicable.

All the borrow sites need better managements in order to avoid or minimize pollution potential and

best practices for managing sites should be adopted.

The proposed project will therefore be carried out together with the implementation of mitigation

measures stated in this report.

8.2 RECOMMENDATIONS

The project area is situated in the dry zone of the country. Compared to the wet zone habitats the

dry zone does not support critical elements of Sri Lanka’s biodiversity such as endemic and

threatened species as was observed during the field study. The habitats present in the project site

are highly degraded. The majority of habitats and species that are affected by the proposed project

are found commonly throughout the dry zone and therefore the overall impact is not significant

considering the extent and magnitude of the impact. It is recommended that project proponent

develop and execute an environmental management plan to ensure best practices during the

implementation of the project. It is also recommended that project proponent undertake to restore

the habitats with indigenous species in order to partially compensate for the loss of habitats due to

the implementation of the proposed project. Finally it is recommended that an appropriate

independent monitoring mechanism with relevant funds be established to ensure that the project

proponent complies with the proposed mitigation measures.

Removal and disposal of debris and excavated material, and increasing the possibilities of erosion

can deteriorate water quality of surface water bodies. Hindrance to vehicular movements, damage

to the crest road surface due to movement of heavy vehicles, temporary storage of earth along the

crest road and elsewhere, impacts due to parking of vehicles and machinery have to be monitored

closely. Noise and vibration and dust generation also can occur due to large-scale construction using

heavy machinery.

Construction and removal of coffer dams is one of the major interventions which need careful

attention

Engineering best practices must be recommended to be adopted by the contractor for the sound

engineering work.

Page 114: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

103 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Borrow sites must be utilized with a proper rehabilitation and safety plan for the protection of fauna

inhabiting the area. All the borrow/quarry areas should be accepted for material exploitation only if

proper approvals from the relevant authorities are obtained.

When complaints are received from the neighbourhood on the environmental issues, immediate

attention and solutions to such issues are recommended.

Page 115: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

104 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ANNEXURES

ANNEX 1: DETAILS OF THE FARMING COMMUNITY

List of person consulted

No Name Position Address Telephone

1 A.D.Wijerathna Block Manager Wijayabapura, Block office 071-8281903

2 K.Wijerathna D.R.P.M D.R.P.M Office, Walikanda 071-2080161

3 E.M.Chandratilaka President Lihini inland fisheries association

137,Dambasewana,Track 1, Pimburattawa

072-42620991

4 D.M.Kulatunga Community Leader No 61,Track 1, Pimburattawa

5 W.A.Tilakarathna President Aralaganwila, Wijayaba FO, Aralaganwila

072-42621148

6 S.A. Indrani Secretary Pimburattawa Parakum FO, Pimburattawa

7 E.A.Ariyawansha President Pimburattawa Parakum FO, Pimburattawa

072-9390440

8 B.M.Basnayaka President Madagama ,Saruketha FO, Madagama

078-9000255

9 Anoma Damayanthi Treasurer Madagama ,Saruketha FO, Madagama

10 K.H.B.Gunarathna President Pimburattawa Ekamuthu FO, Pimburattawa

072-4069380

Page 116: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

105 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ANNEX 2: DETAILS OF THE COST BENEFIT OF AN ACRE OF PADDY LAND IN PIMBURATTEWA

Yield /acre/season Gross Income- Rs. Expenditure item Rs.

2,420 kg (110 bushel * 22kg)

87,120/- (2,420*36) Ploughing (tractor) 8,500.00

Preparation of field bank (activity 1)

3,600.00

Preparation of field bank (activity 2)

4,800.00

Seed paddy 3,500.00

Basel fertilizer 600.00

sowing 3,600.00

Agrochemical 1 3,500.00

Agrochemical 2 1,200.00

Second application of fertilizer

600.00

Agrochemical 3 800.00

Agrochemical 4 1,200.00

Third application of fertilizer

600.00

Harvesting 8,500.00

Transport of paddy 2,000.00

Drying of paddy 3,600.00

TOTAL 46,600.00

Note: Gross income Rs. 87,120/-, total expenditure Rs. 46,600/- therefore net income Rs. 40,520 /=

Page 117: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

106 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ANNEX 3: LOCATION MAP FOR THE IDENTIFIED QUARRY AND BORROW SITES FOR PIMBURATHTHEWA TANK

Page 118: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

107 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ANNEX 4: FAUNA RECORDED FROM PIMBURATTEWA SITES

GROUP Family Species English Name NCS1 Spillway Rubble Storage site

DRAGONFLIES

Libellulidae

Acisoma panorpoides Asian Pintail + -

Orthetrum glaucum Asian Skimmer + +

Orthetrum pruinosum Pink Skimmer + -

Orthetrum sabina Green Skimmer + +

Neurothemis tullia Pied Parasol + -

Rhyothemis variegata Variegate Flutterer - + BUTTERFLIES

Papilionidae

Graphium agamemnon Tailed Jay - +

Pachliopta aristolochiae Common Rose + +

Papilio demoleus Lime Butterfly + +

Papilio polytes Common Mormon + +

Pieridae

Appias albina Common Albatross + +

Appias galene* Sri Lanka Lesser Albatross + +

Catopsilia pyranthe Mottled emigrant + +

Catopsilia pomona Lemon emigrant + +

Delias eucharis Jezebel + +

Eurema hecabe Common grass yellow + +

Leptosia nina Psyche + +

Nymphalidae

Acraea violae Tawny costor - +

Ariadne ariadne Angled castor - +

Danaus chrysippus Plain tiger + +

Danaus genutia Common tiger + +

Elymnias hypermnestra Common palmfly + +

Euploea core Common crow + +

Junonia atlites Grey pansy + +

Junonia iphita Chocolate Soldier + +

Melanitis leda Common evening brown + +

Mycalesis perseus Common bushbrown - +

Neptis hylas Common sailor + +

Parantica aglea Glassy tiger + +

Ypthima ceylonica White Four-ring + +

Page 119: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

108 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

GROUP Family Species English Name NCS1 Spillway Rubble Storage site

BUTTERFLIES

Lycaenidae

Caleta decidia Angled Pierrot + +

Castalius rosimon Common Pierrot + +

Chilades pandava Plains Cupid + +

Jamides bochus Dark Cerulean - +

Jamides celeno Common Cerulean + +

Zizeeria karsandra Dark Grass Blue + +

Zizina otis Lesser Grass Blue + +

Hesperiidae

Iambrix salsala Chestnut Bob - + AMPHIBIANS

Ranidae

Euphlyctis cyanophlyctis Skipper frog + +

Euphlyctis hexadactylus Indian green frog + -

Fejervarya limnocharis Common paddy field frog + +

Hoplobatrachus crassus Jurdon's bullfrog - + REPTILES

Agamidae

Calotes calotes Green garden lizard - +

Calotes versicolor Common garden lizard - +

Scincidae

Eutropis carinata Common skink - +

Varanidae

Varanus bengalensis Land monitor + -

Varanus salvator Water monitor - +

Colubridae

Ptyas mucosa Rat snake - +

Natricidae

Xenochrophis piscator Checkered Keelback - + BIRDS

Phasianidae

Gallus lafayetii* Sri Lanka Junglefowl - +

Picidae

Dinopium psarodes* Sri Lanka Lesser Flameback - +

Ramphastidae

Megalaima zeylanica Brown-headed Barbet + +

Megalaima haemacephala Coppersmith Barbet - +

Alcedinidae

Halcyon smyrnensis White-throated Kingfisher + +

Page 120: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

109 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Meropidae

Merops orientalis Green Bee-eater + +

Merops leschenaulti Chestnut-headed Bee-eater - +

Cuculidae

Clamator jacobinus Pied Cuckoo + -

Eudynamys scolopacea Asian Koel - +

Phaenicophaeus viridirostris Blue-faced Malkoha - +

Psittacidae

Psittacula krameri Rose-ringed Parakeet + +

Apodidae

Cypsiurus balasiensis Asian Palm Swift + +

Columbidae

Columba livia Rock Pigeon CR - +

Streptopelia chinensis Spotted Dove + +

Charadriidae

Vanellus indicus Red-Wattled Lapwing + -

Accipitridae

Haliastur indus Brahminy Kite - +

Ichthyophaga ichthyaetus Grey-Headed Fish-eagle - +

Spilornis cheela Crested Serpent Eagle + -

Ardeidae

Ardeola grayii Indian Pond Heron - +

Egretta garzetta Little Egret + -

Laniidae

Lanius cristatus Brown Shrike - +

Oriolidae

Oriolus xanthornus Black-hooded Oriole + +

Dicruidae

Dicrurus caerulescens White-bellied Drongo + +

Sturnidae

Acridotheres tristis Common Myna + +

Campephagidae

Pericrocotus flammeus Scarlet Minivet - +

Rhipiduridae

Rhipidura aureola White-browed Fantail + -

Page 121: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

110 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

GROUP Family Species English Name NCS1 Spillway Rubble Storage site

BIRDS

Aegithinidae

Aegithina tiphia Common Iora - +

Pycnonotidae

Pycnonotus cafer Red-vented Bulbul + +

Pycnonotus luteolus White-browed Bulbul + +

Cisticolidae

Prinia inornata Plain Prinia + +

Sylviidae

Orthotomus sutorius Common Tailorbird + -

Timalidae

Turdoides affinis Yellow-billed Babbler + +

Dicaeidae

Dicaeum erythrorhynchos Pale-billed Flowerpecker - +

Nectariniidae

Nectarinia zeylonica Purple-rumped Sunbird + +

Nectarinia lotenia Loten’s Sunbird - +

Estrididae

Lonchura striata White-rumped Munia - + MAMMALS

Cercopithecidae

Macaca sinica* toque monkey - +

Hystricidae

Hystrix indica Porcupine - +

Herpestidae

Herpestes brachyurus Brown mongoose + +

Elephantidae

Elephas maximus Elephant EN - +

Cervidae

Axis axis Spotted Deer - +

Canidae

Canis familiaris Domestic Dog + -

Sciuridae

Funambulus palmarum Palm squirrel + +

Leporidae

Lepus nigricollis Black-naped hare + +

Suidae

Sus scrofa Wild boar + +

Tragulidae

Moschiola meminna* Sri Lanka pigmy mouse-deer - +

NCS1 - National Conservation Status (MOE, 2012)

CR - Critically Endangered, EN - Endangered, VU - Vulnerable, * Endemic

Page 122: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

111 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

Reference MOE 2012. The National Red List 2012 of Sri Lanka; Conservation Status of the Fauna and Flora. Ministry of Environment, Colombo, Sri Lanka. viii + 476pp.

Page 123: MG CONSULTANTS (PVT) LTD - damsafety.lk · environmental assessment for rehabilitation of pimburaththewa dam dam safety and water resources planning project dswrpp-af/cs/qcbs/03-02

AN

112 | E N V I R O N M E N T A L A S S E S S M E N T F O R R E H A B I L I T A T I O N O F P I M B U R A T H T H E W A D A M

FINAL REPORT

ANNEX 5: PHOTOGRAPHS – SOCIO ECONOMIC SURVEY

Discussion with Block Manager, A.D.Wijerathna, Wijayabapura, Block Office

Collecting socio-economic data from a community member