TA -8132 REG: Promotion of Direct Investment in Priority Climate … · 2016. 12. 12. · 1.1 investment costs 2 1.2 core gcf indicators 2 1.2.1 direct beneficiaries of adaptation

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ASIAN DEVELOPMENT BANK

ADB loan investment in Fiji, 49001-001: Urban Water Supply and Wastewater Management Project

TA-8132 REG: Promotion of Direct Investment in Priority Climate Technology Projects-Climate Technology Expert (Water and Sanitation)

Preliminary Climate Change Adaptation and Mitigation Report

Date: 25 July 2015

Fiji Urban Water Supply and Wastewater Management Project Climate Change Adaptation and Mitigation Report

Posch & Partners Consulting Engineers Page i

Author(s): Gerhard Knoll

Revision:

Path and Filename: D:\2690\Reports\TA-8132 REG CTech Watsan_20150723.docx

Last edited: 04 November 2016

ABBREVIATIONS

ADB Asian Development Bank

BOD Biochemical Oxygen Demand

CCTV Closed-Circuit Television

CDM Clean Development Mechanism

CHP Combined Heat and Power

CH4 Methane

CO2 Carbon Dioxide

CO2e CO2 equivalent

DMA District Metered Area

EP Equivalent Population

FEA Fiji Electricity Authority

GCF Green Climate Fund

GHG Green House Gas

GSA Greater Suva Area

HH Household

I/I Inflow/Infiltration

IPCC Intergovernmental Panel on Climate Change

IPP Independent Power Producers

KWh Kilowatt hour

ML Million litre

MWh Megawatt hour

NRW Non-Revenue Water

OPEX Operational Expenditure

PPTA Project Proposal Technical Assistance

P&P Posch and Partners Consulting Engineers

SBR Sequencing Batch Reactor

TA Technical Assistance

WAF Water Authority Fiji

WTP Water Treatment Plant

WWTP Wastewater Treatment Plant


Posch & Partners Consulting Engineers Page ii

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY 2

1.1 INVESTMENT COSTS 2

1.2 CORE GCF INDICATORS 2

1.2.1 DIRECT BENEFICIARIES OF ADAPTATION MEASURES 2

1.2.2 CARBON DIOXIDE EQUIVALENT AVOIDED OF MITIGATION MEASURES 2

2 OBJECTIVES 3

3 BACKGROUND INFORMATION AND ASSUMPTIONS 4

3.1 ELECTRIC POWER PRODUCTION AND RELATED EMISSIONS 4

3.2 GREEN HOUSE GAS EMISSIONS 4

3.3 COST ESTIMATES 4

3.4 LIFETIME 4

3.5 EXCHANGE OF PUMPS 4

4 ADAPTATION MEASURES 6

4.1 REWA WATER SUPPLY SCHEME 6

4.1.1 MAIN REASONS FOR NEW INTAKE LOCATION 6

4.1.2 COMPARISON OF BASELINE AND ADAPTATION SCENARIO 8

4.1.3 INCREMENTAL INVESTMENT COSTS IDENTIFIED 8

4.1.4 GCF INDICATORS 9

4.2 EXISTING SEWER MAINS UPGRADE 9

4.2.1 REASONS FOR RELINING OF SEWER LINES 9

4.2.2 COMPARISON OF BASELINE AND ADAPTATION SCENARIO 10

4.2.3 ADAPTATION IMPACTS 10

4.2.4 INVESTMENT COSTS 11


5 MITIGATION MEASURES 12

5.1 NRW REDUCTION 12

5.1.1 COMPARISON OF BASELINE AND MITIGATION SCENARIO 12

5.1.2 MITIGATION IMPACT CALCULATION 12



5.2 KINOYA WASTEWATER TREATMENT PLANT UPGRADE 13





5.3 WASTEWATER SYSTEM EXTENSION 15



Posch & Partners Consulting Engineers Page iii




5.4 TA SEWER SYSTEM OPTIMISATION 16

LIST OF FIGURES

Figure 1: Locations of the originally foreseen and proposed new intake site 7

Figure 2: Pictures from CCTV investigation showing sea water intrusion/infiltration 10

LIST OF TABLES

Table 1: Summary of estimated investment costs 2

Table 2: Estimated t CO2e avoided 2

Table 3: Calculated power saving potential in each catchment 11


Posch & Partners Consulting Engineers Page 2

1 EXECUTIVE SUMMARY

Under the Fiji Urban Water Supply and Wastewater Management Project a series of sub-projects and related investments were defined. The main objective of this report was to identify which of these investments were triggered by climate change, as well as to assess associated specific costs and impacts.

A summary of the most important findings of the Climate Change Adaptation and Mitigation Report is presented hereinafter.

1.1 INVESTMENT COSTS

The identified investment costs1 under the project found to be attributable to climate change mitigation and adaptation measures are summarised in Table 1 below. It can be seen that the total amount was estimated to be FI$ 109.79 million.

Table 1: Summary of estimated investment costs

No. Type Sub-project Investment Costs [FI$ million]

1 Adaptation Rewa WS scheme 46.93

2 Adaptation Exg sewer upgrade 10.35

3 Mitigation Sewer extension 33.75

4 Mitigation NRW 10.76

5 Mitigation Kinoya WWTP 6.00

6 Mitigation TA sewer system 2.00

Total 109.79

1.2 CORE GCF INDICATORS

1.2.1 Direct beneficiaries of adaptation measures

� The new water supply system based on the intake at the Rewa River increases the resilience of the complete GSA water supply system. Therefore, the total number of direct beneficiaries was assessed to be: 290,854 (projected population in service area in 2018)

1.2.2 Carbon dioxide equivalent avoided of mitigation measures

The approximate amount of t CO2e expected to be avoided by the project’s mitigation measures are summarised in Table 2.

Table 2: Estimated t CO2e avoided

No. Type Sub-project t CO2e annually t CO2e lifetime

1 Mitigation Sewer extension 3,958.0 197,900

2 Mitigation NRW 406.5 20,325

3 Mitigation Kinoya WWTP 865.6 12,975

Total 5,230.1 231,200

1 Investment costs excluding contingencies and costs for design and supervision



2 OBJECTIVES

As part of the TA-8526 FIJ: Urban Development Planning and Institutional Capacity Building, the Suva-Nausori Water Supply and Sewerage Master Plan (PPTA) was reviewed and high-priority investments were assessed.

The objectives of this Climate Change Mitigation and Adaptation Report at hand were to

� identify which of these investments were triggered by climate change mitigation and adaptation requirements

� estimate related investment costs

� specify the associated impact of these measures, taking into account the sub-criteria and assessment factors of the Green Climate Fund (GCF) investment framework

This report aims at providing information on the above issues to be used for the funding proposal submitted to the GCF.



3 BACKGROUND INFORMATION AND ASSUMPTIONS

3.1 ELECTRIC POWER PRODUCTION AND RELATED EMISSIONS

In Fiji the Fiji Electricity Authority (FEA) is responsible for production and distribution of electric power. Fiji produces power from a mix of renewable energy sources (approximately 61%, mostly hydropower) and fossil fuels (37%, mainly diesel). The balance of 2% is considered to be Independent Power Producers (IPPs), which can be assumed to be diesel generators and some biomass.

For the purpose of this assessment, it was therefore assumed that power production is based on 62% of renewable energy sources and 38% of diesel fuel.

When diesel fuel is combusted, one litre produces 2.64 kg of CO2. A conservative estimate of Fiji's diesel plant generation consumption is that 1 litre of diesel can produce 4 kWh of electricity.

Fiji dispatches its renewable generation first (for the most part), and uses diesel for the balance. Therefore, it can be concluded that 1 kWh equals the emission of 0.66 kg of CO2 (2.64 kg / 4 kWh). This would be the specific CO2 emission in case the Water Authority Fiji (WAF) would entirely rely on diesel for their power supply. However, under normal conditions, WAF consumes power provided by the FEA, and uses its stand-by power generators only during power cuts.

Thus, for the purpose of this study, the average CO2 emission of 0.25 kg CO2 per kWh (0.66 kg x 38%), respectively the value of 1MWh = 0.25 t CO2e, for electric power provided by the FEA, was applied.2

3.2 GREEN HOUSE GAS EMISSIONS

Calculations of CO2e emanating from wastewater under anaerobic conditions were based on the fact that methane (CH4) is a twenty-one times stronger Green House Gas (GHG) than CO2. Therefore, the emission of 1g CH4/cap/d equals 0.00767 t CO2e/cap/y. Not included in the assessment are the effects of nitrous oxide (N2O), which can play an important role in nutrient removal in Waste Water Treatment Plants (WWTP). However, N2O is subject to ongoing research activities and quantifications of its effects for any process technology are still under discussion.

3.3 COST ESTIMATES

Unit costs for specific items respectively costs for sub-components of the proposed project investments were taken from the PPTA document, Draft Final Report, April 2015 and were not revised for the purpose of this assessment.

Prices for newly introduced items were based on a preliminary market review and the Consultant’s experience.

3.4 LIFETIME

In order to assess the impact of mitigation measures over the component’s lifetime the following service lifetimes were assumed in accordance with WAF’s standard procedures:

� 15 years for electro-mechanical equipment

� 50 years for civil works

3.5 EXCHANGE OF PUMPS

Commonly, the exchange of inefficient and worn out pumps by more energy efficient equipment working at its design point, is considered an appropriate mitigation measure both

2 Data in Chapter 2.1 provided by ADB Energy Specialist



in water supply and sanitation projects. In this project, WAF, on its own account, is currently undertaking the exchange of some of its major water supply pumps and no such activities were foreseen under the loan.

For the wastewater sector, it is foreseen to exchange the pumps of some 31 (of a total of 86) pumping stations. However, in most cases not only the worn out, old pumps will be exchanged; also the capacity of the new pumps will be adapted to new requirements (e.g. increased flow due to new connections). This would make any quantification of energy savings compared to the baseline scenario very unreliable. It was therefore decided among the project stakeholders not to apply for financing for the exchange of sewage pumps to the GCF. Consequently the Consultant refrained from a further analysis in the frame of this assessment.



4 ADAPTATION MEASURES

4.1 REWA WATER SUPPLY SCHEME

This sub-project involves the design and construction of a new water supply source and Water Treatment Plant (WTP) for the Greater Suva Area (GSA) water supply system. Key project components include a new river intake and pumping station on the Rewa River, a new 30ML/d WTP, a 3 ML clear water reservoir and pumping station, a 3ML balancing reservoir and 26km of DN750 pipeline to connect to the existing water supply system servicing GSA.

For many years WAF has proposed to construct a new raw water intake at Site ‘R2’ (near Baulevu) on the Rewa River. However, while originally it was planned to pump extracted Rewa River water to Waila WTP, due to concerns with future salinity levels in the lower reaches of the Rewa River and the potential for mining activity within the Waidina River catchment, this proposal was changed and it is now foreseen to construct a new intake, WTP and related infrastructure further upstream on the same river.

4.1.1 Main reasons for new intake location

Salinity impacts due to climate change

WAF, in studies undertaken during the past years, undertook investigations of the extent of salinity concentrations in the Rewa River from downstream of the Rewa Bridge up to the originally foreseen new intake site “R2” (near Baulevu) (see Figure 1). R2 was identified in the Feasibility Study prepared by GHD in 1999 as the most suitable site. WAF’s investigations suggested that the Rewa Bridge appears to be the current limit of the saline wedge.

GHD’s salinity study concluded that the likely impact of “Greenhouse Effect” (i.e. climate change) sea level rise of 0.5m combined with drought conditions (=low river flows) would result in increased salinity (i.e. > 500mg/l) up to 20km – 23km from the river mouth. It has to be noted that the site “R2”, located some 29km upstream of river mouth, is above the expected extent of increased salinity due to greenhouse effect / climate change as predicted by this model.

However, newer investigations consider a rise in sea level of up to 1m by 2100. In addition, more pronounced droughts are expected in future, which will unavoidably result in lower river flows during these dry periods. Consequently, the salinity wedge is expected to move further up the river systems.

Therefore, the new location of the intake takes into account new insights concerning the impact of climate change on sea water levels and decreased river flows during extended drought periods and provides as such additional security against salinity impacts that are likely caused by climate change in future.



Figure 1: Locations of the originally foreseen and proposed new intake site

Increased resilience of water supply system

Another important argument for constructing a new raw water intake at the Rewa River is that by establishing an additional water supply source the resilience of the whole GSA water supply system would be increased. The system would no longer just be dependent on the Waimanu River system, as it is currently the case, but would have a second raw water source. While the water sources are still all reliant on surface water based systems, the Rewa River is a much larger river system and any impact on stream flows associated with future climate change impacts are not likely to impact extractions for urban water supply. The proposed Rewa water supply scheme will also be designed to be upgradable to allow future flexibility for demand increases and/or changing supply source yields.

In this context it is highlighted that during extended dry periods and based on historical performance and a yield assessment undertaken as part of the 1999 Feasibility Study, the Waimanu River is not capable of supplying the full 150ML/d (year 2013) calculated demand during low flow periods. Considering the demand analysis included in the PPTA it becomes clear that until a new source is operational, additional demand can actually only be covered by NRW reductions.

This future increase in water demand in GSA will be further pronounced by the fact that more and more communities need to relocate from their habitat close to the existing shorelines due to climate change impacts. Many of these communities are likely to move to GSA. For example, 45 communities in Fiji are projected to be relocated in the next five to 10 years because of climate change impacts, as the acting permanent secretary for Foreign Affairs Esala Nayasi confirmed earlier in 2015. These are coastal communities from the maritime islands and those who inhabit the major river banks.

Additional benefits

The proposed new intake at the Rewa River has an additional benefit. While under the project no additional beneficiaries will be connected to the Rewa Water supply scheme, WAF has the intention to fund the future infrastructure to service the numerous villages which might be connected to this scheme once it is operational. Many of the villages, particularly



those along the King’s Road to Korovou are reliant on small rural water supply schemes that are becoming increasingly vulnerable to drought conditions. WAF is currently responsible for providing water tankers for many of these areas when it is required.

4.1.2 Comparison of baseline and adaptation scenario

Baseline scenario

In the 1999 Feasibility Study the preferred option for a new intake at the Rewa River was identified. This option foresaw the following components:

� A river intake and pumping station at Site ‘R2’ (near Baulevu) on the Rewa River, approximately 29km upstream of river mouth, with submersible pumps

� A control building located near the pumping station above 100 flood level

� Electrical distribution line from Princes Road to the pumping station site

� A DN760mm steel rising main approximately 6,300m long between the pumping staion and Waila WTP, including a submarine crossing of the Waimanu River

� A gravel access road from existing roads to the pumping station site

� A 3ML balance tank on the high point of the rising main

� Modifications to the pipework and inlet box at Waila WTP

Adaptation scenario

The actual option foreseen under the project took into account climate change impacts as described above. The proposed project of 30ML/d foresees the following components:

� A new raw water intake (sized 70ML/d) and pumping station (3 Pumps - 200L/s @ 35m (100kW)) at the Rewa River, approximately 49km upstream of river mouth, respectively 600m upstream from its confluence with the Waidina River

� A new 30ML/d WTP on top of the embankment at the same site, including a clear water reservoir of 3ML and a clear water pumping station (3 Pumps - 200L/s @ 110m (275kW))

� 8.5km DN750mm transmission main to Waitolu balancing reservoir (3ML)

� 17.4km DN750mm transmission main to connect to the existing water supply system servicing Nausori and surrounding areas

� Access roads and power supply to the WTP and Waitolu reservoir

4.1.3 Incremental investment costs identified

1. River intake and raw water pumping station:

no additional costs

2. New 30ML/d WTP versus extension of Waila WTP:

No significant cost increase for the WTP itself, but:

Power to site: 5,000,000

Land acquisition / resettlement: 1,000,000 (50% of total costs, as new WTP is required but costs at intake would incur in both scenarios)

3. Balance reservoirs:

3ML balance reservoir in each scenario: no additional costs



4. Transmission main pipelines:

Additional 19.6km of DN750 @ 2,037.4 = 39,933,040

5. Pumping stations: Raw water pumps approximately the same

Clear water pumps will need to have a higher head (some 35m); but also supply areas are not fully identical; therefore, no additional costs are considered.

6. Additional costs for:

Site access: 1,000,000 (assumed 50% of total costs)

Total (FI$): 46,933,040

4.1.4 GCF indicators

� Total number of direct beneficiaries: 290,854 (projected population in service area in 2018)

� Number of beneficiaries relative to total population: 95% (as per WAF connection rate)

� Degree to which the activity avoids lock-in of long-lived, climate-vulnerable infrastructure: 16.6% of GSA water supply will be based on a climate-resilient system instead of locking in alternative long-lived, climate-vulnerable infrastructure

4.2 EXISTING SEWER MAINS UPGRADE

This sub-project comprises the replacement/duplication of 18km of wastewater trunk mains and relining of around 18km of wastewater reticulation and trunk mains that are at the end of their asset life. For the purpose of this assessment (and for GCF funding) only the 18km relining activities were considered, basically due to the fact that the sewer lines chosen to be relined are especially prone to sea water rise and related inflow/infiltration (I/I) due to their location close to the shoreline. A more detailed justification of this adaptation measure is provided hereinafter.

4.2.1 Reasons for relining of sewer lines

Location of pipes

Pipes identified to be relined are generally located less than 200m from the shoreline and below 1m above sea level, in some cases even below sea level. Areas such as Suva City and Walubay are mostly reclaimed land and the groundwater table in these areas is very high, causing an increased rate of I/I. These pipes will therefore be particularly prone to sea level rise due to climate change. During high tides the percentage of sea water in wastewater at a series of sewage pump stations was verified by corresponding analysis undertaken by WAF.

Practicality of traditional remedial works

The areas where the pipes to be relined are located have generally been fully developed and doing common remedial works in open trenches will cause a high degree of disturbance with high associated social costs when compared to the relining process. Opting for relining instead of open trench pipe replacement was therefore considered to be the most economic option.

Age and materials of pipes

The sewer pipes identified to be relined are mostly made of asbestos cement (AC) and vitrified clay and are more than 40 years old, i.e. have or will be reaching their asset life. AC and vitrified clay pipes are prone to be affected by gases emanating from sewage, such as



hydrogen sulphides (H2S), which have caused corrosion of the upper parts of gravity flow (open channel flow) pipes.

Operators observations and CCTV Inspection

It is part of the daily routines of WAF’s wastewater field team to remove pipe blockages causing wastewater overflow. These operators are well aware of high I/I rates, particularly applicable to those low lying coastal areas, which they observe during their work.

Since the field operator’s observations are limited to sewer damages close to manholes, closed-circuit television (CCTV) investigations were carried out to gain a better picture of the sewer pipe conditions. The CCTV pictures shown in Figure 2 provide clear evidence of significant I/I to the sewer system.

Figure 2: Pictures from CCTV investigation showing sea water intrusion/infiltration

4.2.2 Comparison of baseline and adaptation scenario

Baseline scenario

� 18 km of sewer pipes continue to be without relining and are prone to I/I

Adaptation scenario

� 18 km of sewer pipes are relined and with decreased I/I

4.2.3 Adaptation impacts

It is obvious that the above described scenario with I/I to pipes close to the shoreline has a direct impact on pumping costs for sewage. However, a quantification of the I/I itself as well as of related pumping costs is a very difficult task as there are many uncertain factors having a great impact on these issues. What is evident is that if no measures were taken the situation would become worse with sea water levels expected to rise. Apart from increased pumping costs, another adverse effect of I/I is the dilution of wastewater, which leads to problems at the WWTP such as hydraulic overloading and decreased treatment efficiency.

In an attempt to estimate the power savings that could be achieved by relining, the following approach was followed:

Figures for I/I rates of old pipes in literature vary widely. Metcalf & Eddy (1981) gives a range of 0.2 to 28 m³/d/ha for existing sewers; Japanese studies recommend using 10 to 20% of domestic and commercial wastewater flow as infiltration; in Vietnam 250l/d/m² of pipe were used in studies, and the US Massachusetts state requires an I/I removal study if infiltration exceeds 10l/h/m for DN250 pipes respectively 12l/h/m for DN300 pipes. The latter two sources are very similar in their value and were therefore applied.

Permissible standards for newly laid respectively relined pipes are more consistent and in this case the Australian standard AS2566.2 for buried flexible pipelines was chosen. Thus, in



case of a DN300mm pipe the infiltration rate was assumed to be reduced from 12l/h/m to 0.15l/h/m.

This reduced infiltration rate was then applied catchment per catchment to the total 18km pipe length to be relined. Since the pump head is known in each catchment it was possible to calculate the power saving for each of it. An overall pump efficiency coefficient of 45% was applied. The calculations revealed that in total some 41,902kWh/y, respectively 4.3% of the total pump energy for wastewater in these catchments, may be saved due to the relining activity. This equals a yearly saving of 10.48 t CO2e. Due to high degree of uncertainty in this calculation and the relatively low saving potential this number was not taken into further consideration and the driving argument for the relining of sewer pipes is the adaptation aspect.

Table 3 shows the results of the calculations carried out for each catchment.

Table 3: Calculated power saving potential in each catchment

4.2.4 Investment costs

The total investment costs for the relining works of 18km of DN225-DN300 pipes, which corresponds to 12% of the total reticulation system length of the concerned catchments, were estimated to be FI$ 10,350,000.


� Degree to which the activity avoids lock-in of long-lived, climate-vulnerable infrastructure: 12% of sewer lines of concerned catchment areas will be relined (18km of sewers in a distance of less than 200m to the shoreline and lying below 1m above sea water level)

PS CatchmentPump Head

(m)

Sum of ass.

reduction in I/I

Flow Post-Re-

Pumping Energy (kW)Shaft Power n= 45%

(kW)

Amra PS 2.7 3024 0.022246674 0.049437053

Carptrac SPS 1.9 2213 0.011458355 0.02546301

Desbro PS 9.7 1722 0.045513366 0.101140814

Golf Course PS 0 4346 0 0

Gym PS 2.4 3593 0.023500393 0.052223096

Matau PS 5 2473 0.033695639 0.074879198

Nadawa 2 8.5 3679 0.08520834 0.189351867

Nadawa 3 31.2 4882 0.41505804 0.922351199

Nadawa 4 3.1 13600 0.114882527 0.255294504

Narere 2 PS 3.1 338 0.002856632 0.00634807

Narere 5 PS 12.8 5430 0.189413308 0.420918463

Narere 6 19.3 985 0.051817132 0.115149181

Nausori 2 PS 0 3395 0 0

Nausori Main PS 0 4700 0 0

Nepani PS 52.2 3805 0.541278804 1.202841786

NLP PS 0 0 0 0

Parade PS 1.2 3116 0.010187877 0.022639726

Pratt PS 3.4 4930 0.045673362 0.10149636

Raiwaqa SPS 2.5 11186 0.076207602 0.169350228

RIfle Range PS 5.2 0 0 0

Robertson PS 6.1 2502 0.041592603 0.092428006

Rokobili PS 2.9 2945 0.023275794 0.051723987

Sonoma PS 0.7 3991 0.007613544 0.016918987

Suva Point 1 7.6 5545 0.114841607 0.255203571

Upper Easter Trunk Main 35.9 2867 0.280502533 0.623338961

Viria PS 0.5 6647 0.009056318 0.020125151

Western Trunk 0.3 8109 0.006629222 0.014731604

Grand Total 110025 2.15 4.78 kW

41902 kWh/year



5 MITIGATION MEASURES

5.1 NRW REDUCTION

Current Non Revenue Water (NRW) values are high at 51%, and are foreseen to be reduced to 27% by 2033. Under the project several key activities including water main and meter replacement, leak surveillance and repair, establishing District Metered Areas (DMAs) and pressure management are foreseen. According to WAF records, in 2013 83% of NRW was caused by technical losses (leaks, accounting for 24,873ML/y).

Over the past 2 years WAF has carried out a programme of water meter replacement across the country, but the programme is limited by capital funding. Therefore, funding within the ADB loan foresees to enable an accelerated pace of meter replacements within the GSA water supply system. This programme will target commercial losses. Further, leaking water main replacement has been included in the project, since many of the water mains have reached a point where full replacement is more cost effective than continued repair and maintenance. In addition, the NRW reduction measures include a programme for establishing DMAs and adequate pressure management. Mains replacement and pressure management target predominantly technical water losses.

Clearly, NRW reduction measures should be implemented by WAF independently from climate change. However, due to funding limitations it is questionable whether this issue would be given the required priority and the envisaged NRW reduction could actually be achieved, if no financing is specifically dedicated to this activity.

5.1.1 Comparison of baseline and mitigation scenario

Baseline scenario

� It is assumed that NRW will be reduced by ongoing WAF investments by 3% (from 51 to 48%)

Mitigation scenario

� It is assumed that due to the NRW measure under the loan NRW will be reduced by an additional 6% (from 48 to 42%)

5.1.2 Mitigation impact calculation

NRW reduction, and thereof the reduction in physical water losses, has a direct impact on energy consumption for water supply. In addition, it reduces the need for exploring additional water sources. Energy consumption of WAF for potable water supply (production and distribution) in the GSA was 32,648 MWh in 2014.

As outlined in the PPTA the targeted overall reduction of NRW within 20 years is 24%, respectively 9% (to 42%) until 2018, which is the horizon chosen for this assessment. It was assumed that approximately 6% thereof are due to the measures under the project, and 3% due to the ongoing WAF investments. Considering the share of 83% technical losses, and a yearly average water production in GSA of approximately 53,471ML, this corresponds to some 2,663ML (53,471ML x 0.83 x 0.06) which is not lost through leakage and thus does not need to be produced and distributed.

In the GSA the specific energy demand for water supply (production and distribution) was 610.6 kWh/ML in 2014. Therefore, a total of 1,625.9 MWh (610.6kWh/ML x 2,663ML) can be saved by the above described measures. This corresponds to 406.5 t CO2e per year (applying the specific CO2 emission for Fiji outlined in Chapter 3.1). For the expected lifetime period of 50 years this equals 20,325 t CO2e.




The estimated investments targeting the technical losses only were estimated to be:

� Water main replacement: FI$ 7,300,000

� Pressure management FI$ 3,460,000

It has to be noted that the final investments targeting NRW can only be defined after the currently ongoing detailed condition assessment programme is finalised.


� Expected tonnes of carbon dioxide equivalent (t CO2e) to be reduced or avoided annually: 406.5

� Expected decrease in energy intensity of buildings, cities, industries and appliances: 1,625.9 MWh (5%) of electric power consumption in potable water production and distribution

5.2 KINOYA WASTEWATER TREATMENT PLANT UPGRADE

Current Kinoya WWTP capacity is rated at 128,000 EP, and WAF is to undertake an upgrade of the plant to 175,000 EP during the next 2 years. The ADB project envisages an extension of the treatment capacity to 277,000 EP in order to service priority backlog sewerage areas and new development areas over the next 10-15 years.

Presently, WAF is implementing a Clean Development Mechanism (CDM) project, which is supposed to reach its full design capacity later in 2015. The main objective of the project is to capture the digester gas (biogas) from the anaerobic digesters and flare the same in an enclosed biogas flaring unit. The volume of combined sludge production (through primary and secondary treatment) from the sewerage treatment plant was estimated to be 469m3/d in 2015. Before the installation of the flaring unit, the digester gas (biogas) generated during anaerobic decomposition was vented into the air and the digested sludge was discharged to the sludge drying beds (the latter practice will still continue). The project activity was estimated to contribute to emission reductions of an average of 22,471 t CO2e per year.3

The specific goal of this sub-component of the project is not just to flare the biogas produced at the WWTP, but to use it for energy production. Obviously biogas production is to significantly increase as a consequence of the extension of the WWTP’s capacity. This will help to significantly reduce the Operational Expenditure (OPEX) of the WWTP by reducing the expenditure for energy consumption and consequently avoid GHG emissions related to this production.


Baseline scenario

� All the biogas produced at the WWTP is flared in the biogas flaring unit

Mitigation scenario

� All the biogas produced at the WWTP is turned into electric power by the installation of combined heat and power (CHP) equipment


Since at this point it is still unknown which treatment technology will be applied for the extension of the WWTP under the project it is not possible to calculate the exact amount of sludge to be digested, respectively the energy that can be produced. In order to minimise

3 UNFCCC CDM-SSC-PDD, Kinoya Sewerage Treatment Plant GHG Emission Reduction Project, Version 03.4, February 12, 2011



energy consumption (and maximise energy production) at all stages of wastewater and sludge treatment, optimised process selection, instrumentation and control measures are important and will be considered. In addition, co-digestion of food waste, fats, oils and grease (FOG) and organic industrial waste collected through the trade waste programme currently implemented will increase the potential for biogas production. Installation of high-efficiency and low-maintenance combined heat and power (CHP) installations for the conversion of biogas into electric energy (for example, co-generation with improved efficiencies and micro turbines) usually results as the most economical option for biogas reuse at WWTPs and has therefore become the common international standard approach.

The Kinoya WWTP has to be designed for nutrient treatment (N, P), which reduces the potential for power generation and increases the energy consumption. Based on international case studies, biogas and power generation compared to power consumption the following assumption can be made for the specific conditions at Kinoya WWTP:4

� Biogas production: 22 l/EP/y

� Power generation from biogas: 13 kWh/EP/y

� Power consumption: 25 kWh/EP/y

From the above figures it can be derived that at least 50% of the power consumption of the WWTP could be produced by using biogas. This conservative estimate was made due to the fact that the existing plant with a capacity of 128,000 EP is based on SBR technology, which is an energy intensive technology.

It has to be noted that treatment technologies which are characterised by low energy demand during operation, at the same time have a lower potential for energy generation. Nowadays, well designed and maintained WWTPs are actually able to cover significantly higher percentages than 50% of their energy demand or are even energy autonomous.

Applying the assumed specific power consumption of 25 kWh/EP/y to the envisaged treatment capacity of 277,000 EP results in a yearly power consumption of 6,925 MWh. Considering the presumably 50% power production at the plant this results in 3,462.5 MWh savings, respectively in 865.63 t CO2e per year (applying the specific CO2 emission for Fiji outlined in Chapter 3.1). For the expected lifetime period of 15 years for electro-mechanical equipment this equals 12,975 t CO2e.


Additional investment costs are limited to installations for biogas utilisation in CHP.

Further investigations on actually produced biogas quantity and quality will be required, once the many boundary conditions impacting these are known. Ideally these should be supported by a comprehensive sampling campaign of biogas on the ground. Expected investment costs for the required equipment are as follows:

� Biogas pre-treatment, gas holder, flare: FI$ 2,500,000

� CHP with microturbines: FI$ 3,500,000


� Expected tonnes of carbon dioxide equivalent (t CO2e) to be reduced or avoided annually: 865.63

� Expected decrease in energy intensity of buildings, cities, industries and appliances: 3,462.5 MWh (50%) of electric power consumption due to CHP installation

4 East Asia and Pacific, Wastewater to Energy Processes: a Technical Note for Utility Managers in EAP countries, The World Bank, January 2015



� Avoids lock-in of long-lived, high emission infrastructure in wastewater collection and treatment: intention to apply less energy intensive treatment technologies which guarantee the economic sustainability of the plant

5.3 WASTEWATER SYSTEM EXTENSION

This sub-project foresees the extension of the wastewater reticulation system to service backlog sewerage areas and the construction of new regional pumping stations to service future developments in the Waila / Nakasi region. However, for the current assessment only the extension to existing residential areas is considered. The goal of the extension is to service an additional 15% of households (HH) in backlog areas, which corresponds to 4,500 lots, and which would increase the sewer connection rate in GSA from currently 36% to 51%.


Baseline scenario

� The 4,500 lots continue to be served by septic tanks

Mitigation scenario

� The 4,500 lots are connected to the sewer reticulation system and the sewage is treated adequately in a WWTP


GHG emission values from Septic Tanks reported in literature range from 11.0g CH4/cap/d 5 to 25.5g CH4/cap/d 6. The latter value from the IPCC model assumes that half of the influent BOD to the septic tank is converted anaerobically.

It is known that septic tanks located in warm climates usually result in higher methane emission rates compared to cool climates in developed countries, where the before mentioned 11.0 g CH4/cap/d were actually measured. In addition, the hardness of the water supply appears to influence the overall flux of emissions, with soft water systems having higher gas fluxes. Both factors, warm climate and soft water supply, apply to the specific conditions in Fiji.

Therefore, for the purpose of this assessment a value of 25.5g CH4/cap/d was used. This value is equivalent to 0.1955 t CO2e/cap/y.

Considering the total number of 4,500 HH to be connected through the project and an average HH size of 5 persons, this results in 4,397.8 t CO2e/y. In order to account for some anaerobic conditions during sewage collection and transport to the WWTP, as well as for the requirement of sewage pumping, a reduction of 10% of the value was considered. The final value of CO2e emissions avoided by the extension of the sewer system was calculated to be 3,958.0 t CO2e/y. For the expected lifetime period of 50 years this equals 197,900 t CO2e.

5.3.3 Investment Costs

The total investment costs for the wastewater system extension to 4,500 existing residential areas were estimated to be FI$ 33,750,000. This was based on an average house

5 Harold L. Leverenz et al. (2010). Evaluation of Greenhouse Gas Emissions from Septic Systems. University of California, Davis.

6 IPCC (2007) Climate Change (2007) Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri, and A. Reisinger (eds.)]. IPCC, Geneva, Switzerland.



connection length of 15m, and considered an allowance of 25% for extras (depth, crossings, terrain).


� Expected tonnes of carbon dioxide equivalent (t CO2e) to be reduced or avoided annually: 3,958

� Avoids lock-in of long-lived, high emission infrastructure in wastewater collection and treatment: 4,500 septic tanks will be taken out of operation

5.4 TA SEWER SYSTEM OPTIMISATION

The wastewater system in the GSA consists of 86 sewage pump stations, 44km of sewer rising main and trunk gravity mains, and over 330km of sewerage reticulation. In addition, there are 5 WWTP servicing the area. However, in fact only Kinoya WWTP is of real importance as it services about 97% of connected customers. Currently, Kinoya is foreseen to be further extended and be the central WWTP for GSA, since the other 4 small WWTP have limited scope for extension.

The wastewater system outlined above may have optimisation potential. The number of 86 sewage pump stations seems to be high for a catchment area of the size of GSA, even though it is recognised that the topography is rather hilly and varied. The aim of an optimisation would be to reduce the number of pump stations, and, eventually, increase the capacity of the remaining ones, which would improve the overall efficiency of sewage pumping. At the same time the need for sewage pumping may be reduced by introducing one or more additional WWTP in other parts of GSA service area rather than centrally treat the vast majority of wastewater in the Kinoya WWTP only. Apart from other considerations, the preparation of a hydraulic model, which needs to be calibrated by using real flow and pressure measurements taken in the field, will contribute to define an optimised sewage reticulation system. A comprehensive multi criteria analysis including a cost benefit analysis should define whether a central or decentralised approach for wastewater treatment will be the preferred one. In this context it needs to be noted that independently of the outcome of the latter analysis the envisaged treatment capacity in Kinoya will not be below the 277,000 EP envisaged under the project, if the backlog areas continue to be connected and the sewer connection rate reaches 90% as targeted by WAF.

In addition to the above outlined scope a capacity development / institutional strengthening component should be included in the TA, focusing on fostering the overall ability of WAF for managing the wastewater operations.

It was estimated that the budget for the TA would be in the range of FI$ 2,000,000 if it is headed by an international engineering consulting firm.

Documents

TA -8132 REG: Promotion of Direct Investment in Priority Climate … · 2016. 12. 12. · 1.1 investment costs 2 1.2 core gcf indicators 2 1.2.1 direct beneficiaries of adaptation