samoa sanitation and drainage project ssdp - ipes.ws · 2016-04-29 · samoa sanitation and...

Samoa Sanitation and Drainage ProjectSamoa Sanitation and Drainage Project

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ADB Loan No. 2026 SAM (SF)ADB Loan No. 2026 SAM (SF)

Project Implementation Assistance ConsultantProject Implementation Assistance Consultant

Presentation to IPES Presentation to IPES

2020thth September 2007September 2007

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Outline of Project Components

• Drainage

• Floodway rehabilitation and improvement

• Drainage rehabilitation and improvement

• Flow modelling and Measurement

• Sanitation – Sewerage Scheme

• Pressure sewer scheme for CBA and SNAs

• WWTP on BP site

• Effluent disposal at Landfill site

• Sanitation – On-site

• Survey of Septic tanks in low-lying area

• Program for replacement and upgrading

• Future management and septage disposal

• Capacity Building

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Current Issues, Status and Proposed Action

Where have we got to?

• Some aspects of original scope were not viable

• Land and financial issues

• Technical proposals developed in a series of ‘Technical Advisory Notes’ (TANs)

• Technical advise given to Govt to revise scope & adopt best fit both technically & financially

• Design proceeded based on TANs to maintain progress

• TAN’s provided Govt with alternatives & recommendations.

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• Some aspects of original scope are not viable

• Technically sub-optimal

• Will not be able achieve total project objectives

• Land issues significant impact on overall design

• Estimates prepared during project design were low

• Expectations of public that total solution will be achieved

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• Some aspects of original scope are not viable

• Technical proposals for project components developedin a series of Technical Advisory Notes’ (TANs)

1. Floodways & Drainage

• Also includes flow modelling and measurement (not a TAN item)

2. CBA / SNA Sewerage

3. Septage Treatment & Disposal

4. On-site Sanitation Management (future)

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Why Drainage and Floodways? Why Drainage and Floodways? –– Reduce / mitigate Reduce / mitigate FloodFloodinging

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Current Issue – 1. Floodways & Drainage

TAN – the Realisation that ultimate solution is FAR beyond the scope & funding of this project led to …

• 4-phase solution for floodways(Gasegase, Asaga & Fugalei)

• Prioritising balance of floodway and drainage work

• Prioritising components of drainage work

• Flow Measurement and Modelling

• Basic approach has not changed – but costs and extent of work have been refined in the conceptual design process

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Floodway Plan

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Floodway Map

• INSERT DRG C-001 HERE

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Floodway Phases – Flood Return Period

1. Minor works & cleanup (2 – 5 years)

• Now – works d/s of Asaga confluence(~ 0.2 ha of land – bend easing)

• Later – upstream works(~ 0.2 ha of land – bend easing)

2. Declare a floodway reserve (n/a)(Administrative Action only)

3. Acquire and clear the floodway reserve (> 5 years)

4. (27 ha land, minor demolition costs)

5. Build a flood channel (50+ years)(No further land – major construction)

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Floodway Phases –

3. Acquire and clear the floodway reserve3. Acquire and clear the floodway reserve

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Floodway Phases –

4. Build a flood channel4. Build a flood channel

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Floodway Phases – Costs (WST x 1,000)

ITEM LAND WORKS O & M

1. Minor works (ha)

• Now 0.2 2,100 150

• Later 0.2 500 0

2. Floodway reserve 0.0 0 0

3. Acquire & clear land 27 1,000 30

4. Build flood channel 0.0 12,000 90

LONG-TERM TOTAL 27.4 15,600 240

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Floodway Issues – Mangroves: Development Impacts

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Floodway and Drainage Prioritisation –

Item ToR TAN Current

Floodway Lengthupgraded 2,850 2,850 2,150

Drainage lengthrehabilitated 2,425 ??? ~1,000

Floodway costs (WST x 1,000) (Phase 1 – ‘now’) 3,920 3,920 2,100

Drainage costs 1,400 1,400 3,300

Total Capital 5,320 5,320 5,400

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Drainage Prioritisation –

• Provide an outlet

• Provide capacity

• Reduce time of flooding

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Report & Issues for Project Report & Issues for Project Steering Committee Steering Committee –– 1 Dec 2006 1 Dec 2006

Drainage Prioritisation – Works plan

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Report & Issues for Project Report & Issues for Project Steering Committee Steering Committee –– 1 Dec 2006 1 Dec 2006

Drainage Prioritisation –

INSERT DRG C-002

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Flood Modelling and Measurement

• To be a separate sub-contract (now deferred possibility of WaSSP funding)

• Bid documents have been drafted and reviewed by IA/PMU (would need to be converted to EU format)

• Builds on work by EU/SOPAC and TA project (a number of other activities with MNRE)

• Includes three components

•Flow modelling

•Acquisition of Flow Measuring equipment

•Design of fixed Flow Measurement Structures

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Fixed flow measurement structures can have a dual-function

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Current Issue – 2. Sanitation Improvements

2(a) - Sewerage scheme – (i) pipework

Topography and sub-surface conditions in Apia not considered favorable conventional sewerage …Investigations have shown a pressure sewer scheme

• is cheaper and easier to construct

• will cause less disruption, and

• can be extended or modified more easily

• Has lower operating costs and

• Simplifies the treatment process

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Report & Issues for Project Report & Issues for Project Steering Committee Steering Committee –– 1 Dec 20061 Dec 2006

Sewerage scheme – (i) pipework

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Sewerage scheme – (i) pipework

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Sewerage Scheme – Pipework Cost Comparison (WST x 1,000)

SCHEME LAND WORKS O & M

1. Conventional Sewers 0* 5,100 170

2. Pressure Scheme 0 3,500 130

* - cost for location of relift pump stations is assumed to be nil

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2(a) - Sewerage scheme – (ii) treatment

Original ToR proposal was for a ‘package plant’ on the BP site and wetlands for final ‘polishing’ treatment. But environmentally, the mangroves are both important and sensitive… Investigations show

• A high-standard ‘nutrient removal’ package plant is required, with an infiltration gallery

• Wetlands are of uncertain benefit in nutrient reduction and are hard to manage

• Mangroves can’t be used as ‘wetland’

• Site is not big enough!

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Sewerage scheme – (ii) treatment

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Sewerage Scheme – Treatment Cost Estimate (WST x 1,000)

SCHEME LAND WORKS O & M

1. BNR Plant with chemical 0* 6,000 900Phosphorus dosing

2. Standard plant –generally consider to be about 25 to 30% less than

BNR (not actually costed because could not comply with environmental standards)

* - assumes Radio Station area or ‘old nightclub’ is public landand available at no cost

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Current Issue – 2. Sanitation Improvements 2(b) – On-site Sanitation

Basically three major components

(iii) New and upgraded septic tanks

(iv) Improved pump-out arrangement

(v) Septage treatment and disposal

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2(b) – On-site Sanitation – (iii) new tanks

Topography and sub-surface conditions in the flat area of Apia may require special measures… ‘Blanket survey’ and investigations show

• Tanks need replacement but no-one willing to pay the capital cost

• Current Building Code provisions are basically sound, although a little undersized

• Minor modifications required for flood areas

• Main need is for improved construction quality (compliance with code)

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On-site Sanitation – (iii) new tanks

Key issues are

• How to improve average construction quality and tank performance

• Number of potential properties (Blanket survey found 1,000 not 2,500)

• How to bear the cost – WST12,000

• How to organise the financing

• Should Govt be getting involved?

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2(b) – On-site Sanitation –

(iv) improved management of pump-outs

Issues are:

• ToR specified two ‘10 cu metre’ pump-out trucks – very large, standard is 5 cu m

• Cost of ONE 5 cu m truck is ~USD200 –which is total budget for two

• Who are to own / use truck(s) – leased to a management contractor?

• Question of management arrangements yet to be considered in detail

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2(b) – On-site Sanitation –(v) Septage treatment and disposal

TAN (#3) – discovered that ToR proposals were not viable. Treatment necessary to stabilise material (including WWTP sludge). Site ‘unfriendly’ to any major lagoon or drying bed solution. Proposals were:

• Anerobic digestion in tanks, followed by

• Dewatering using a belt press.

• Leachate / supernatant treated in lagoons

• Disposal of dried solids to the landfill

• Detail design and construction in a separate contract

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On-site Sanitation –(v) Septage treatment and disposal

Subsequent review found drying beds may not work properly in Samoa’s climate and now mechanical dewatering in a ‘filter press’ is proposed.

Key issues are:

• Mechanical maintenance (possibly include

on-going operation in the contract)

• Who to manage? (SWA or MNREM)

Currently budget issues are delaying bidding process.

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Septage treatment and disposal

ProProcess Outline (with Drying Beds)cess Outline (with Drying Beds)

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On-site Sanitation – Costs (WST x 1,000)

ITEM LAND CAPITAL O & M

1. Replace Septic Tanks 0 800,000* (0)

2. Operate management 0 1,000 200contract (purchase truck, now defered)

3. Design and Build Septage 0 720 150and sludge disposal plant

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Current Status of Project.

• Floodways and Drainage contract bid round one rejected because of no compliant bidding procedure.

• WWTP and PS contract bid round one rejected because of non compliant bidding & high cost.

• Floodways and Drainage contract round two appears from preliminary evaluation that a result will be obtained.Construction expected to commence early 2008.

• WWTP and PS contract bid round two appears from preliminary evaluation that a result will be obtainedConstruction expected to commence early 2008

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Current Status of Project.

• Septage treatment facility bids likely to be posted in next few weeks.

• Flood modelling bids have been deferred

• Septage transportation truck deferred

• Training of SWA staff planned for next 6 months overseas (reviewing options and sources of support with possibility of Waste Water Treatment Operators Certification from NZ)

Samoa Sanitation and Drainage ProjectSamoa Sanitation and Drainage Project

SSDPSSDP

ADB Loan No. 2026 SAM (SF)ADB Loan No. 2026 SAM (SF)


Fa’afetai!Fa’afetai!

samoa sanitation and drainage project ssdp - ipes.ws · 2016-04-29 · samoa sanitation and...

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