Idea Transcript
Technical Assistance Consultant’s Report
Project Number: 42391 June 2010
Republic of Vanuatu: Port Vila Urban Development Project (Cofinanced by the Government of Australia) Supplementary to Final Report (August 2011)
Prepared by EGIS Bceom International In Joint Venture with Qualao Consulting, Ltd. For Asian Development Bank
This consultant’s report does not necessarily reflect the views of ADB or the Government concerned, and ADB and the Government cannot be held liable for its contents. (For project preparatory technical assistance: All the views expressed herein may not be incorporated into the proposed project’s design.
The Asian Development Bank TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT PPTA CONSULTANT’S REPORT
PHASE 1: SITUATION ANALYSIS AND MASTER PLAN FORMULATION,EXECUTIVE SUMMARY Date Reference Version In Joint Venture With:
QUALAO CONSULTING, LTD.
30 November 2010 EPA90710F/R0 1
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 1: Situation Analysis and Master Plan Formulation EXECUTIVE SUMMARY
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Document quality information
General information Author(s)
Peter Dawes
Project name
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT
Document name
PHASE 1: SITUATION ANALYSIS FORMULATION,EXECUTIVE SUMMARY
Date
30 November 2010
Reference
EPA 90710F
AND
MASTER
PLAN
Addressee(s) Sent to: Name
Organisation
AKM Mahfuzuddin Ahmed Principal natural resources Specialist PAHQ
Tha Aian Development Bank
Sent on (date): 01 December 2010
Copy to: Name
Organisation
Willie Watson, Manager Projects
Ministry of infrastructure and Public Utilities, government of Vanuatu
Sent on (date): 01 Decemcer 2010
History of modifications Version 1
Date 30 November 2010
Written by Project Team
Approved & signed by: Peter Dawes, Team Leader
PPTA Consultants Report Egis Bceom International (France) in association with Qualao Consulting Ltd. (Vanuatu)
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 1: Situation Analysis and Master Plan Formulation EXECUTIVE SUMMARY
Contents I.
Introduction ............................................................................. 1
II.
Sanitation ................................................................................. 4
III.
Drainage ................................................................................... 5
IV.
Phase 2 : Detailed Investment Program ................................ 9
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TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 1: Situation Analysis and Master Plan Formulation EXECUTIVE SUMMARY
List of figures Figure 1 – The Planning Area...................................................................................................... 2
List of tables Table 1 - Summary of Master Plan Proposals and preliminary Cost Estimates (US $) ........ 7 Table 2 - Alternative Investment Scenarios............................................................................... 8
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TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 1: Situation Analysis and Master Plan Formulation EXECUTIVE SUMMARY
I.
1
INTRODUCTION
1. The purpose of the current Project Preparatory Technical Assistance (PPTA) study is twofold:
First, to prepare a Master Plan for sanitation and drainage in Port Vila and its surrounding peri-urban areas, for the period 2010-2025. This is referred to as Phase One of the Study.
Secondly to prepare a detailed investment program for the development of the sanitation and drainage services of Port Vila and its surrounding areas. This is referred to as Phase 2.
2. The Master Plan attempts to set out the main physical and non-physical interventions required to provide for the sanitation and drainage needs of the Greater Port Vila region up to the year 2025-30. Physical intervention by works alone will not be sufficient to secure a lasting and sustainable improvement in living conditions and the required environmental benefits and the Master Plan therefore proposes a mix of civil works, equipment, social, administrative, managerial and environmental steps which must be taken, over time to ensure positive, sustainable development within the sector under study. 3. The Master Plan is comprised of 6 volumes containing over 600 pages of detailed and largely technical information. A report of such a size is too unwieldy for the majority of readers, especially the senior officials who will be required to make the all-important decisions on the formulation of an investment program to implement the Plan. This summary document has therefore been prepared to provide a more easily digestible snapshot of the overall Plan. By the term “sanitation” is meant the removal, transportation and final disposal of liquid waste from all sources, residential, commercial, institutional and industrial. This term refers to “black” liquid waste arising from toilets, and to “grey” liquid waste arising from kitchens and bathrooms. By the term “drainage” we mean the collection, transportation and final disposal of rainfall, the result of storms and cyclones and to the management of natural watercourses, such as streams and rivers. 4. The PPTA Study commenced on 1st June 2010 and has been active for some 6 months prior to the preparation of the Master Plan. The initial part of the Study, lasting one month, was involved with making a detailed analysis of the existing situation, focussing on sanitation and drainage, for Port Vila and its surrounding area. This information was delivered by way of an Inception Report presented on 30th June 2010. 5. Further work during the latter part of Phase 1, has concentrated on i) further studies to firm up the initial findings during the Inception period, and ii) designing broad strategies outline plans and potential project components to address deficiencies and defects observed during the Inception period and later. 6. The above process has involved a number of sectoral studies which when viewed as a whole, give us a composite picture of the current status of all aspects of sanitation and drainage in Port Vila and an indication of future needs. These have included:
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Planning studies aimed at precisely defining the limits of the area to be studied and at establishing the dynamics of past and future projected population growth in spatial and numerate terms (Planning Area agreed shown overleaf)
Figure 1 – The Planning Area
Socio-economic studies to ascertain the current perceptions and prevalent practices adopted by the residents of Port Vila and particularly the level of importance given to sanitation and drainage issues and their priority for being addressed. These studies were also targeted at establishing our potential client‟s, the residents of Greater Port Vila, willingness and ability to pay for improved service delivery and the nature and extent of improved services which would be practically, culturally and socially most acceptable for them.
Studies of current trends in environmental change and climate change to evaluate the negative environmental changes taking place due to long-standing inattention to the sanitation and drainage sectors.
Institutional studies to determine the strengths and weaknesses of the institutions involved in the planning, building, operation and management of assets and systems.
Technical studies to determine the extent and condition of existing systems for the treatment and disposal of sanitation and drainage effluents and to plan and consider the feasibility of available technical options for the safe and sanitary disposal of those effluents.
Macro-economic and financial studies to determine the economic cost of not addressing the issues revealed in the parallel studies.
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7. The Socio-Economic Profile carried out as part of this PPTA (see Volume 6) has indicated a widespread demand at grass roots level for improvements in particularly, storm drainage and flood control and to a slightly lesser extent, in improved accessibility to clean safe and hygienic public and private sanitary facilities. It has also clearly highlighted a lack of general knowledge of good hygiene practices and the need to raise awareness of sanitation issues and good hygiene practices among potential users. In particular the proper use, management and maintenance of communal and public sanitary infrastructure. 8. An institutional review (see Volume 4) has been carried out which has revealed a number of weaknesses in existing managerial and operational practices, notably the lack of trained technical personnel available in public sector organisations. These weaknesses will need to be remedied and current systems and practices replaced or strengthened to ensure the longevity and sustainability of future infrastructure investments. 9. A review of environmental aspects (see Volume 5) has revealed a deterioration in the water quality of those bodies of water currently receiving drainage and sanitation effluents, not yet at dangerous levels but which requires careful monitoring. Also marine habitats close to the Study Area particularly in Fatumaru Bay and Port Vila Harbour show evidence of stress as evidenced by areas of dead corals and sea grasses. Other environmental problems noted were odours and poor air quality in the vicinity of public conveniences and the generally dilapidated state of many of the private sanitary facilities, particularly in the peri-urban areas. The present sludge disposal area at the Bouffa landfill site is also an object for concern as untreated sludge directly accesses the porous limestone rock sub-strata which underlies the whole of Port Vila and by this means harmful elements can enter the ground water table. 10. A parallel review of climate change aspects (also Volume 5) has revealed that sea level is predicted to rise over the next 50 or so years by a significant amount. This coupled with the climatic fragility of Efate Island, being prone to Tsunami, earthquakes and cyclones, that there is a pressing need for any development proposals to be rigorously climate proofed. 11. Macro-economic studies carried out by the project Team have estimated the economic cost to the Government of Vanuatu of not addressing the prevailing sanitation and drainage issues. It has been projected that simply doing nothing would lead to a number of wide-ranging costs including increased health care costs, increased unemployment, higher maintenance costs for further deteriorating infrastructure, higher transport costs for delays and diversions on flooded and dilapidated roads and perhaps most important of all a reduction in tourism revenue, resulting from a projected fall in visitor numbers due to the very visible deterioration of the City, which is the main entry point for the majority of tourists. Studies made so far indicate that such economic costs could total as much as US$ 2.7 billion over the planned 15 year life of the Master Plan. 12. Technical studies with a particular focus on sanitation and drainage facilities (see Volumes 2 and 3) have revealed that little or no sanitation infrastructure exists. What does exist are small treatment works serving individual developments, tourist hotels and some institutional buildings such as Port Vila Hospital. These facilities were limited in scope and in many instances were found to be inoperative. Domestic sanitation for established residential is mainly by septic tanks, which are periodically emptied by a privately owned fleet of tankers. While this system appears to be working reasonably well, the final disposal of the effluent at the existing Bouffa landfill site is most unsatisfactory and requires urgent action. In the outlying peri urban areas residents have to rely on simple pit latrines or the bush or the beach.
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13. Storm drainage infrastructure is also seriously inadequate. Many partial and disconnected drainage systems exist, but these systems are ineffectual as they tend to simply shift the flooding problem downstream. The systems found during the team‟s studies were also badly designed and constructed, and few or no records of their location and details are recorded. In the Study Area the PPTA team has identified 44 separate locations where serious flooding is a recurrent problem. 14. Flooding problems are exacerbated by the poor condition of Port Vila‟ roads. Many roads in residential areas are unsealed. The roads in the Central Business District which have been sealed are seriously deteriorated, littered with potholes and cracks. When heavy rains come rainwater accumulates and often with great velocity rushes down the numerous slopes. This action scours the surface gravel from the unpaved roads and further damages the paved roads, the resulting debris then enters the existing inadequate drainage system which soon becomes blocked and inoperative. 15. Despite the complexity and seriousness of the problems encountered, the PPTA Team have found that solutions exist. II.
SANITATION
16. For a City having the size status and importance of Port Vila, there is no real alternative other than to move as rapidly as possible towards a piped sanitation system, draining all effluents to a sewage treatment facility, treating those effluents to an internationally accepted standard and then discharging benign effluents to an appropriate receiving water body. There are two options for achieving this as set out in great detail in Volume 3. Basically the two options are: Option 1. Least cost solution This option will provide a minimalist, effective but short-term solution to some of the most pressing sanitation problems. The rationale behind this option is to reinforce, modernise and stream line the existing practice of using domestic, on property, septic tanks as the primary resource for the treatment of effluents. The major focus of the investment programme would then be to improve the removal, transport and treatment of the sludge from those septic tanks to a properly designed and constructed, sludge treatment and disposal facility. The tanker fleet would also be upgraded and its management improved. An important part of this option is that although it may be possible to improve the existing sludge treatment facility at Bouffa, this site is not ideal for the purpose. The PPTA Team strongly advise that a piece of underutilised agricultural land off the Mele Road and close to Port Vila Golf and Country Club, be purchased. This would serve two purposes. First it would provide a site for the treatment of sludge, but secondly and more importantly it would provide a site for the creation of a full scale sewage treatment to be available when, inevitably this becomes unavoidable. Other components included in this Option would be the creation of a number of Multipurpose, multi user sanitary facilities in Villages and peri-urban settlements selected on the basis of a formal demonstration of need and an expression of their willingness to contribute to the capital cost and maintenance of facilities. Building would be provided housing toilet washing and bathing facilities, to be used on a communal basis. Under this option Public toilets, principally in the City Centre and located at the major sporting facilities would be upgrade, rebuilt or refurbished. As all the new and refurbished facilities to be created under this Option would be using the septic tank system the component allows for a necessary strengthening of effluent and PPTA Consultants Report Egis Bceom International (France) in association with Qualao Consulting Ltd. (Vanuatu)
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sludge control and monitoring facilities and finally includes the creation of new laboratory, ideally operated by the Ministry of Lands and Natural Resources to be responsible for testing and monitoring systems and the strengthening of the legislative structure. The estimated cost of this option is US$ 5.6 Million equivalent initially. This would meet demands up until 2020. By which time to meet continuing population growth an extension to the facilities provided or Stage 2 would be required. The estimated cost of a second stage of similar works is US$ 4.2 Million equivalent. Option 2, Full Service Solution The second and much preferred Option is to go immediately for the construction of a wastewater treatment facility and a piped wastewater collection system. This would involve the construction of a network of pipelines and pumping stations conveying effluent from it‟s source to the Wastewater Treatment facility proposed on the Mele Road site identified during Phase 1. This option would also include the reconstruction provision of Public toilets in the City centre and the provision of Communal village and community Sanitation facilities in the peri urban villages and settlements. For this option, however it would not be required to build and equip a separate laboratory as this would be an integral part of the Wastewater treatment works. The cost of this option would be considerably higher than for Option 1, but could be partially offset by the capacity to produce energy from bio-gas as a by-product of the wastewater treatment process. Energy thus created would be available to run the plant itself and initial calculations suggest there may be a surplus of energy which could be returned to the National Grid. The estimated cost of this option is US$ 25.5 Million equivalent, initially. This would meet demands up until 2020. By which time to meet continuing population growth an extension to the facilities provided or second stage would be required. The estimated cost of a second stage of similar works is US$ 18.0 Million equivalent. The Second stage would cater for additional requirement up until the year 2030, the result of population growth and City expansion III.
DRAINAGE
17. Defining a drainage strategy for the Master plan period is complicated by the need to integrate any sustainable and effective drainage system with a program of road improvement, the formulation of which is outside the scope of the Terms of Reference of the present PPTA Study. However in preparation of the detailed investment program, which will be undertaken during the second phase of the PPTA Study, it is assumed that those roads for which new drainage structures are proposed will be upgrade or rehabilitated with improved surfacing, gutters, kerbs and channels to ensure the long term effectiveness of the drainage works to be constructed. 18. During detailed studies in Phase 1 it was found that Greater Port Vila is divided, due to its natural topographical features, into 39 separate drainage basins or catchment areas. PPTA Consultants Report Egis Bceom International (France) in association with Qualao Consulting Ltd. (Vanuatu)
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Each of those areas has been studied carefully, by original survey or by relying on existing data. For each of these catchments a drainage solution has been prepared for inclusion in the Master Plan. Then the catchment solutions have been aggregated to provide packages of drainage works which are logical. 19. By this means the 39 catchment areas have been packaged to form 11 separate and “stand alone” sub-projects. These are listed in the following paragraphs, together with their preliminary costings. The first sub-project, the Drainage Rehabilitation and Maintenance Program, which consists of cleaning and rehabilitating parts of the existing drainage system, plus the purchase of essential drain cleaning and road sweeping equipment, is regarded as essential to the success of all of the other packages, regardless of which implementation scenario is selected. 20.
The following implementation scenarios are envisaged
Implementation scenario Do Nothing
Baseline case, carry out no maintenance and make no improvements: will result is progressively deteriorating conditions for surface water drainage, nuisance flooding, small flood damages and erosion of roads, increasing pollution of waterbodies.
Do minimum
Carry out regular inspection and maintenance of existing drainage systems. Implement Code of Practice for Surface Water Drainage to be a statutory requirement for all new developments.
Drainage only in highpriority catchments
As „do minimum‟ but improve or provide new drainage systems in catchments with a recent history of flooding problems.
Drainage of all catchments
As „drainage only in high priority catchments‟ but with programme of works and street adoption for all urban and peri-urban catchments.
21. The decision required, therefore is to make a selection from the 11 sub-projects based on cost, economic advantage to be gained and the perceptions and requirements of stakeholder. It is the opinion of the PPTA Team that all sub-projects should be considered for inclusion in the investment program. A list of the 11 sub-projects together with their tentative costing is given below.
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Table 1 - Summary of Master Plan Proposals and preliminary Cost Estimates (US $)
DRAINAGE
Component
Cumulative cost
Priority 1. Drainage Rehabilitation and Maintenance Program
$ 255,000
$ 255,000
Priority 2. Tebakor
$ 3,018,000
$ 3,273,000
Priority 3. Municipal – Fres Wota
$ 3,856,000
$ 7,129,000
Priority 4. CBD
$ 477,000
$ 7,606,000
Priority 5. All Lini Highway North
$ 328,000
$ 7,934,000
Priority 6. Seven Stars (Ohlen)
$ 1,114,000
$ 9,048,000
Priority 7. Seven Stars (Anabrou)
$ 777,000
$ 9,825,000
Priority 8. Independence Park
$ 233,000
$10,058,000
Priority 9. Nambatu
$ 404,000
$10,462,000
Priority 10. Bauerfield Culvert
$ 88,000
$10,550,000
Priority 11. Seaside
$ 324,000
$10,874,000
Source : Consultant‟s Estimate
22. Alternative investment program Scenarios are numerous due to the 11 individual drainage projects, one or more of which may be selected for inclusion, below are 3 suggested scenarios, illustrating high medium and low capital cost. Each Scenario is aimed at meeting the 2020 development target. It is assumed that meeting the 2030 sanitation targets would be the subject of a follow-up Project, as would be those drainage areas not taken up in the initial Project. The third column of the table indicates the possible accumulated (see para. 11) economic cost to the Government of Vanuatu of adopting each scenario.
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Table 2 - Alternative Investment Scenarios
SCENARIO I (maximum) Expenditure
Implement all Master Plan recommendations to meet Year 2020 demands.
(million US$)
Notional Cost to GoV Economy (million US$)
36.3
Zero-300
SCENARIO 2 (medium) Expenditure
Implement all Drainage Projects + Minimal Sanitation (septic tanks only)
(million US$)
Notional Cost to GoV Economy (million US$)
16.4
500-1000
SCENARIO 3 (minimum Expenditure
Implement Minimum Drainage + Minimum Sanitation (septic tanks only)
Million US$)
Notional Cost to GoV Economy (million US$)
5.75
800-2500
Source : Consultant‟s Estimate
23. It is very apparent that investment in physical infrastructure alone will not secure lasting benefits in the sectors under study. Physical investments will be required to go hand in hand with a range of carefully targeted financial, managerial and educational investments which may be termed „soft‟ investments. 24. Such soft investments are equally or perhaps even more important than the „hard‟ or physical investments. Considerable experience and technical expertise are required to prepare infrastructure projects. Engineers and technicians spend considerable time on the design, phasing, implementation methodology and all the other technicalities required to put infrastructure on or into the ground. Therefore a similar amount of care, professionalism and effort must be put into devising appropriate systems for the financing, operating and management of that infrastructure. 25. At this stage of the Master Planning process, Government and its development partners are presented with a number of options as to how the master plan targets may be achieved. These options differ in terms of timing, financial requirements, technical complexity, managerial requirements and their need for sensitisation of involved and affected stakeholders. As an example, in the case of the sanitation component the two major options 1) with a sewage treatment works and piped collection system, and 2) with only the reinforcement of the septic tank and sludge disposal system, each will require substantially different management approaches. The selection of the preferred technical option will be required as a precursor to the design of the necessary and appropriate support systems. PPTA Consultants Report Egis Bceom International (France) in association with Qualao Consulting Ltd. (Vanuatu)
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26. Therefore early consideration of the available options and a decision on a preferred option is vital to maintain the momentum of the preparation of an appropriate investment programme and making the initial step towards solving the Sanitation and Drainage problems of Greater Port Vila. IV.
PHASE 2 : DETAILED INVESTMENT PROGRAM
27. The delivery of the Draft Master Plan Report marks the conclusion of Phase 1 of the Port Vila Urban development Project. The commencement of the second phase will be in January 2011, and will focus initially on a Master Plan Presentation and Workshop. To include all stakeholders, principally The Government of Vanuatu, AusAID and ADB. 28. The main outcome from this workshop must be a decision on the options to be selected for inclusion in the Detailed Investment Program, and to be the subject of the subsequent feasibility studies. 29. This information is essential to the PPTA Team, as the exact size and scope of the investment program will dictate how the inputs from the PPTA Team will be organised and mobilised to complete the Phase 2 work by the target date of 25th April 2011. Some changes to the in-put schedule agreed at the time of contract negotiations may be anticipated
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The Asian Development Bank TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT PPTA CONSULTANT’S REPORT
PHASE 2: DRAINAGE FINAL REPORT Date Reference Version In Joint Venture With:
QUALAO CONSULTING, LTD.
25 April 2011 EPA90710F/R0 1
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TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 2: Drainage Final Report March 2011
Document Control
Recipients Attention Name AKM Mahfuzuddin Ahmed Principal Natural Resource Specialist, PAHQ
Copy Name Mr. Willie Watson Manager, Projects
Organisation ADB, Head Office, Manila
Organisation Ministry of Infrastructure and Public Utilities, Vanuatu
History of Modifications Submission Date Name Signature
30 NOVEMBER 2010 Peter DAWES, Consultant Leader/Urban Planner
Version
Date
Prepared by
1
19 March 2011
Leighton Williams
External Control
Modifications
J-C Elis
Other information Author Date Reference Document Title
Leighton Williams March 2011 EPA90710F/R1 Drainage Final Report
PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 2: Drainage Final Report March 2011
iii Abbreviations
ABBREVIATIONS
ADB AUSAID CBD CBDAMPIC CC DEC DGMWR DLA DFEM DPH EA EA EU FMA GAP GDP GHG GIS GRAMP HIES IA IDF IEE ISPS JICA LARF/LARP LSF MFEM MIA MIPU MJSW MLNR MOH MOL MOU MSL NACCC NLSC NZAID O&M PAA PICCAP PIEPSAP PIGGAREP PIREP PMU
Asian Development Bank Australian Agency for International Development Central Business District Capacity Building for the Development of Adaptation Measures Project Climate Change Department of Environment & Conservation Department of Geology, Mines and Water Resources Department of Local Authorities Department of Finance and Economic Management Department of Ports & Harbour Executing Agency Enumeration Area European Union Financial Management Assessment Gender Action Plan Gross Domestic Product Greenhouse Gas Geographic Information System Governance Risk Assessment and Management Plan Household Income and Expenditure Survey, Household Income and Expenditure Survey Implementation Agency (Rainfall) Intensity-Duration-Frequency Initial Environmental Examination International Ships & Ports Security Japanese International Cooperation Agency Land Acquisition and Resettlement Framework and Plan Land Sector Framework Ministry of Finance and Economic Management Ministry of Internal Affairs Ministry of Infrastructure and Public Utilities, Ministry of Justice and Social Welfare, Ministry of Justice and Social Welfare, Ministry of Justice and Social Welfare Ministry of Lands and Natural Resources Ministry of Health Ministry of Lands Memorandum of Understanding Mean Sea Level National Advisory Committee on Climate Change National Land Steering Committee New Zealand's International Aid & Development Agency Operation and Maintenance Priorities and Action Agenda Pacific Island Climate Change Project Pacific Islands Energy Policies and Strategic Action Planning Pacific Island Greenhouse Gas Abatement through Renewable Energy Project Pacific Islands Renewable Energy Programme Project Management Unit PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 2: Drainage Final Report March 2011
PPA PPTA PPU PRIF PVMC PWD SBU SPO SUDS TA TOR TVL UN UNDP UNELCO UNFCCC UNICEF UNIFEM URA Vt WHO
iv Abbreviations
Physical Planning Area Project Preparatory Technical Assistance Physical Planning Unit Pacific Regional Infrastructure Facility Port Vila Municipal Council Public Works Department Small boring unit Shefa Planning Office Sustainable Drainage Systems Technical Assistance Terms of Reference Telecom Vanuatu Limited United Nations United Nations Development Programme Union Electrique du Vanuatu Limited United Nations Framework Convention on Climate Change United Nations Children's Fund, United Nations Children's Fund United Nations Development Fund for Women Utilities Regulatory Authority Vatu World Health Organization
PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 2: Drainage Final Report March 2011
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Contents
CONTENTS A. B. 1. 2. C. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. D. 1. 2. 3. 4. 5. 6. 7. E. 1. 2. 3. 4. 5. F. 1. 2. 3. 4. 5. G. 1. 2. 3. 4. 5. H. 1. 2. 3. 4.
Introduction ................................................................................................. 1 Drainage Sub-Projects ............................................................................... 1 Sub-projects ..................................................................................................... 1 Scope of Sub-projects ..................................................................................... 2 Drainage Infrastructure Proposals Generally ............................................. 3 Principles adopted for design .......................................................................... 3 Port Vila level of development ......................................................................... 5 Roads .............................................................................................................. 5 Hydrology ......................................................................................................... 6 Drainage design............................................................................................... 6 Pipe material .................................................................................................... 7 Pipe sizes ........................................................................................................ 8 Manholes and catchpits ................................................................................... 8 Gully design ..................................................................................................... 8 Rapid Works .................................................................................................... 9 Methods of pipe laying ................................................................................... 10 Unit rates ....................................................................................................... 11 Staged development ...................................................................................... 11 Foul Sewerage ............................................................................................... 11 Asset Management ........................................................................................ 12 Drainage Maintenance Program ............................................................... 12 Description of existing situation ..................................................................... 12 Description of sub-project .............................................................................. 12 Justification for sub-project ............................................................................ 12 Special equipment requirements ................................................................... 13 Initial cleaning and repair ............................................................................... 14 Long-term system maintenance .................................................................... 14 Indicative cost estimate ................................................................................. 14 Tebakor .................................................................................................... 15 Description of existing situation ..................................................................... 15 Description of sub-project .............................................................................. 16 Justification for sub-project ............................................................................ 16 Design proposal ............................................................................................. 17 Quantity and cost estimates .......................................................................... 17 Municipal – Fres Wota .............................................................................. 18 Description of existing situation ..................................................................... 18 Description of sub-project .............................................................................. 19 Justification for sub-project ............................................................................ 19 Design proposal ............................................................................................. 19 Quantity and cost estimates .......................................................................... 20 Central Business District (CBD) ............................................................... 21 Description of existing situation ..................................................................... 21 Description of sub-project .............................................................................. 23 Justification for sub-project ............................................................................ 24 Design proposal ............................................................................................. 24 Quantity and cost estimates .......................................................................... 25 Lini Highway (north).................................................................................. 26 Description of existing situation ..................................................................... 26 Description of sub-project .............................................................................. 27 Justification for sub-project ............................................................................ 27 Design proposal ............................................................................................. 27
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Contents
5. Quantity and cost estimates .......................................................................... 29 Seven Stars (Anabrou) ............................................................................. 29 1. Description of existing situation ..................................................................... 29 2. Description of sub-project .............................................................................. 30 3. Justification for sub-project ............................................................................ 30 4. Design proposal ............................................................................................. 31 5. Quantity and cost estimates .......................................................................... 31 J. Seven Star (Ohlen) ................................................................................... 32 1. Description of existing situation ..................................................................... 32 2. Description of sub-project .............................................................................. 33 3. Justification for sub-project ............................................................................ 33 4. Design proposal ............................................................................................. 33 5. Quantity and cost estimates .......................................................................... 33 K. Independence ........................................................................................... 34 1. Description of existing situation ..................................................................... 34 2. Description of sub-project .............................................................................. 35 3. Justification for sub-project ............................................................................ 35 4. Design proposal ............................................................................................. 35 5. Quantity and cost estimates .......................................................................... 36 L. Nambatu ................................................................................................... 37 1. Description of existing situation ..................................................................... 37 2. Description of sub-project .............................................................................. 37 3. Justification for sub-project ............................................................................ 37 4. Design proposal ............................................................................................. 38 5. Quantity and cost estimates .......................................................................... 38 M. Seaside..................................................................................................... 39 1. Description of existing situation ..................................................................... 39 2. Description of sub-project .............................................................................. 39 3. Justification for sub-project ............................................................................ 39 4. Design proposal ............................................................................................. 40 5. Quantity and cost estimates .......................................................................... 40 N. Summary Estimate ................................................................................... 41
I.
LIST OF FIGURES Figure 1 - Truck street sweeper ............................................................................................... 14 Figure 2 - Trailer mounted water jetter ..................................................................................... 14 LIST OF TABLES Table 1 - Summary cost estimate for drainage maintenance program .................................... 15 Table 2 - Summary quantity and cost estimates for Tebakor for full catchment drainage ....... 18 Table 3 - Summary quantity and cost estimates for Component 1 sub-project at Tebakor ..... 18 Table 4 - Summary quantity and cost estimates for Municipal – Fres Wota for full catchment drainage.................................................................................................................... 20 Table 5 - Summary quantity and cost estimates for Component 1 sub-project at Municipal – Fres Wota ................................................................................................................. 21 Table 6 - Summary quantity and cost estimates for Component 1 sub-project for CBD .......... 26 Table 7 - Summary quantity and cost estimates for Lini Highway North for full sub-catchment drainage.................................................................................................................... 29
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Table 8 - Summary quantity and cost estimates for Component 1 sub-project for Lini Highway North .........................................................................................................................29 Table 9 - Summary quantity and cost estimate for Seven Stars Anabrou for full sub-catchment drainage.................................................................................................................... 32 Table 10 - Summary quantity and cost estimates for Component 1 sub-project for Seven Stars Anabrou .................................................................................................................... 32 Table 11 - Summary quantity and cost estimates for Seven Stars Ohlen for full sub-catchment drainage.................................................................................................................... 34 Table 12 - Summary quantity and cost estimates for Component 1 sub-project for Seven Stars Ohlen ........................................................................................................................34 Table 13 - Summary quantity and cost estimates for Component 1 sub-project for Independence ........................................................................................................... 36 Table 14 - Summary quantity and cost estimates for Component 1 sub-project for Nambatu . 39 Table 15 - Summary quantity and cost estimates for Component 1 sub-project for Seaside .. 40 Table 16 – Summary of principal quantities for Component 1 ................................................. 41 Table 17 – Summary of estimated cost for Component 1 by sub-project ................................ 41
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Introduction
1. This section provides elaboration of Component 1: Drainage of the Drainage and Sanitation Investment Project based on the master plan prepared During Phase I, Situation Analysis and Master Plan Formulation. Specifically it describes the 'climate proofed' preliminary designs of the physical drainage infrastructure to be constructed under the project, including opportunities to rehabilitate, and upgraded existing infrastructure. This includes cost estimates for the work. 2.
This section should be read in conjunction with three supporting documents: 1. Code of Practice for Surface Water Drainage 2. Component 1: Drainage Drawings 3. Component 1: Calculations
3. The Drainage proposals have been prepared in compliance with the ‘Code of Practice for Surface Water Drainage’. This document was prepared and presented during Phase I of the PPTA and only minor corrections and amendments have been made during Phase II. The objective of the document is to fill the gap for a code of practice for drainage infrastructure not covered by the Draft National Build Code, and to set rules, design criteria and methods which can in future be used by both the public and private sectors in Port Vila. The Code of Practice has been used and thoroughly tested during development of the design proposals. 4. The preliminary, feasibility-level designs of the drainage infrastructure presented as drawings and calculations are based on the results of inspections, inventory and survey. These include site layouts and preliminary engineering drawings sufficient to describe the proposed drainage works. The costs to construct, operate and maintain the drainage infrastructure has been determined and incorporated into the Project cost estimates. 5. The drainage designs and O&M are 'climate proofed' by provision of sufficient capacity, use of durable materials, and minimum maintenance designs to ensure that they will be able to withstand projected climate change impacts over the long-term. 6. The drainage designs are also developed, as far as is practical, according to the principals of Sustainable Drainage Systems (SUDS), a short description of which is at Appendix 6 of the Code of Practice. Two of the principal objectives of SUDS are to reduce the peak volumes and improve the chemical and bacterial water quality of drainage discharges. This approach mitigates the impact of drainage discharge on the coastal zone, it can be anticipated that the progressive implementation of the Drainage Strategy under the Master Plan will have positive impacts by improvement to the water quality over existing drainage discharges. B. 1.
Drainage Sub-Projects
Sub-projects
7. The proposals for the Drainage Component can be considered as ten sub-projects. The first sub-project is the Drainage Maintenance Program for the purchase and operation of street and drain cleaning equipment and minor repair works. The Drainage Maintenance Program component is essential for the effective operation and assured maintenance of the other nine components, and indeed all existing and future drainage infrastructure in Port Vila. The remaining nine components are for repair, upgrading and construction of new drainage
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systems in priority catchments where there are high incidence of drainage problems and nuisance flooding. The full list of sub-projects is as follows: 1
Drainage Maintenance Program
2
Tebakor catchment
3
Municipal – Fres Wota catchment
4
CBD, which comprises six discrete sub-catchments
5
Lini Highway North which comprises eight discrete sub-catchments
6
Seven Stars (Anabrou)
7
Seven Stars (Ohlen)
8
Independence
9
Nambatu
10
Seaside
8. At the end of Phase I an eleventh sub-project was listed for Bauerfield Culvert. However, inspection and cleaning under the Rapid Works (section C.10) found the culvert to have residual structural life and that flooding had been cause by blockage by cut woody vegetation which had been left in the drainage ditch. The culvert capacity is sufficient. Fitting a trash screen at the culvert inlet was considered but this would require maintenance inspection and cleaning and since the problems occur because of inadequate maintenance a screen would achieve no purpose or indeed aggravate flooding if maintenance is neglected. The subproject was dropped because there is no structural or hydraulic problem and all that is necessary is correct and timely maintenance. 2.
Scope of Sub-projects
9. The Drainage Maintenance Program is designed to start and make routine the system for managing and maintaining the existing and planned extended drainage systems. 10. The other nine sub-projects are for new drainage systems. In places these drains are on the same line as existing drains and there is the opportunity to incorporate or make use of these (section C.11). However, inspection under the Rapid Works program (section C.10) indicated there was little possibility to retain the existing drains in the medium to long-term and it is assumed that they will be replaced when each sub-project is constructed. 11. The drainage networks for the nine sub-projects are designed for the long-term with capacity for fully developed drainage catchments (Clause 6.1.2 Code of Practice). The designs described by this report are for future primary drains for complete sub-catchments. Additional drains can connect to the primary drains without overloading the primary drains. 12. In some catchments it is not necessary or desirable to build the full networks at this time. This applies particularly to catchments with unmade or deteriorated roads which cannot benefit from the proposed pipe and channel drainage the roads are sufficient to direct runoff into the drains. In these cases it is preferable not to implement construction of drains for these PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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roads until such time as the roads are made good. At that stage the channels, gullies and turnouts can be constructed together with the roadworks. This also reduces the cost of Component 1. The extent and sub-projects where this applies is included with the sub-project descriptions sections E to M. C.
Drainage Infrastructure Proposals Generally
13. A uniform approach and consistent standards have been used in developing the preliminary designs of the physical drainage infrastructure. These are described in this section. The specifics, assumptions and special requirements for each of the sub-projects are described in subsequent sections. 1.
Principles adopted for design
14. The proposals follow the established principles and conventions for urban drainage but with the addition of SUDS measures where possible. Travelling from the top of a drainage catchment to the outfall the following components are seen: •
Overland flow of runoff is preserved to maximise the infiltration of rainfall into the underlying and very permeable (coral) limestone rocks (SUDS compliant).
•
Grass verges such as found in many residential streets are to be preserved and promoted, and where room and land slope is suitable grass swales to be formed to attenuate runoff, promote bio-treatment of runoff and further promote infiltration (SUDS compliant).
•
The existing widespread practice of collecting roof water drainage for drinking water and other domestic uses is to be continued and encouraged for new build (SUDS compliant).
•
If roof drainage is not collected then promote the discharge to a correctly designed and constructed soakaway within the boundaries of property (see National Building Code for Vanuatu, in Draft) (SUDS compliant).
•
Drainage systems begin downstream of the above measures thereby ensuring that only excess runoff flows down the drainage system to the outfall (SUDS compliant).
•
To minimise the use of pipe drains in streets with low gradients where flow along the edge of the road will be sub-critical (Clause 6.2.4 Code of Practice), especially residential streets where there are grass verges, use dish drains (channels) on the upslow side (Drawing D.SD.06, Volume 2.1). The outfall to be via a grated gully with sump (see gullies below).
•
Again to minimise the use of pipe drains in steep streets where flow along the road will be super-critical (Clause 6.2.4 Code of Practice), or in other situations where a dish drain will provide too little capacity or is otherwise unsuitable, use open channel drains. These to generally follow the vertical alignment of the road and have a dished or ‘V’ section invert (bottom) to concentrate flow and keep sediment which has entered the drain moving to a gully or catchpit where it will settle out and can be removed (Drawing D.SD.06). Surface runoff from the road and elsewhere will enter the drain via ‘turnouts’ or ‘drainage grips’. The outfall to include a sump or catchpit where sediment that has entered the channel is trapped and settled out and can be emptied by a vacuum tanker on a routine basis.
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•
At some point, further down the system, pipe drains will be used. In general piped drains shall continue until the outfall except in circumstance where there are good reasons to return to open channel.
•
It is a requirement that roads are regularly swept to keep to a minimum the quantities of sediment and litter washed into the drains by runoff (see section D).
•
Water enters piped drains from roads and other paved areas via a drain gully. This is a small drainage structure with: o
a flat grating flush with the road surface (Type R), or
o
a combination of flat grating and a weir inlet in an upstand matching the profile of a barrier kerb (Type K), or
o
a weir gully typically a 0.5 to 1.5 m long opening in the face of the kerb with a grill to prevent entry of litter (Type W).
The requirements for gully inlets are specified at Clause 7.5 of the Code of Practice. All three types have in common that they are set over a sump (gully pot) with a high level outlet so that any sediment that enters the gully is captured and does not flow into the carrier drain. These sumps must be emptied with a vacuum tanker at intervals of sufficient frequency to ensure they are never completely filled (see section D). •
Even with road sweeping and sediment traps such as gully pots a fraction of sediment will still enter the drain, more so when rainfall is heavy so that runoff is fast, turbulent and capable of transporting lots of sediment and litter. Therefore drainage pipes and open channel drains are designed to achieve a minimum ‘self cleansing velocity’ of 1.5 m/s. Ideally this velocity will be achieved or exceeded at flows which occur regularly but as a minimum the velocity should be reached for the design storm (generally 1 in 2 years historical return period). It is not everywhere possible to achieve the minimum velocity and in these cases there may result an increased maintenance requirement which could require periodic cleaning of the drain with water jetting equipment (see section D).
•
The topography of Port Vila is characterised by a sequence of plateau and plains, steep hillsides and flat coastal areas. Ideally the velocity in a drain should be constant or gradually increasing moving downstream to keep sediment in motion through the system. This is not everywhere possible; often a drain down a steep slope with fast velocity will have to be followed by a flat section with slow velocity. At these ‘break of slope’ there is high potential for sediment to settle out and result in blockage. The mitigation proposed is to provide ‘catchpits’ which capture the sediment. These are in all respects similar to manhole chambers but instead of a half-pipe channel they have a wet sump (Drawing D.SD.01). Sediment falls into the sump and must be emptied with a vacuum tanker at intervals of sufficient frequency to ensure they are never completely filled.
•
Grey water connections and polluting discharges are a serious ongoing problem for the existing drainage system. Numerous restaurants and businesses, especially in the CBD, are discharging untreated waste and ‘grey water’ to the surface water drains. Where proposals have been made for replacing drains then these connections will be identified and not reconnected. The person discharging will have to dispose waste to a septic tank or other suitable system.
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•
Areas with particularly high risk of pollution include vehicle fuelling stations, car wash areas, loading bays, car parking areas, etc. The minimum good practice requirement for pollution control is that surface water runoff from these areas must pass through an oil separator, silt trap and other appropriate device before excess runoff is discharged to the drainage system. Requirements for oil separators are specified at Clause 9 of the Code of Practice. Such sites are generally in private ownership and it is recognised that enforcing this requirement retrospectively will meet objection. However, without such measures the objective to clean-up surface water discharges will be seriously compromised. In many developed countries it is mandatory and conditional on obtaining consent to discharge to provide such facilities and operators can be subject to heavy fine for each incidence of polluting discharge (polluter pays principle).
•
Wherever possible outfalls into coastal waters shall be set at a minimum elevation 1.86 m MSL 1973 to minimise tide locking up to year 2060, see Clause 3.12 of the Code of Practice. Suitable measures to control scour will be required and several outfalls on steep drains will require an energy dissipator.
•
Where existing low ground level precludes setting outfalls above elevation 1.86 m MSL 1973 (CBD and Lini Highway North) then the outfall will be fitted with a tidal flap gate to prevent sea water entering the drainage system but at the same time allow drainage to flow into the sea whenever there is sufficient hydraulic head on the land side to force open the gate.
2.
Port Vila level of development
15. The CBD and other areas of Port Vila including the wealthier sub-divisions already have the character and appearance of a modern developed urban area. It can be assumed that areas with informal housing and unmade roads will in the medium to long-term also catch-up. Therefore, in order to be in the long-term sustainable and climate-proofed the drainage proposals must be appropriate for a fully developed urban environment. Provision of open drains or ditches in the existing developed areas would not be appropriate nor would it achieve the desired long-term objectives. Indeed, many of the road corridors, and sidewalks where these exist, are already too narrow and unsafe for pedestrians; it is not considered tenable that space be taken from these corridors for open drainage systems; drainage must go underground. 3.
Roads
16. The drainage proposals must be integrated within the long-term priorities for urban infrastructure development in and around Port Vila, particularly with the development plans for the road sector. It will be necessary to coordinate the detailed design and implementation of the drainage (and sanitation) sub-project with those for road development. 17. In order to prepare drainage design calculations it has been necessary to make assumptions for the road cross sections which most probably will become commonplace in the future. It is considered unlikely that the road sector plans will be significantly different from the assumptions made. The typical cross sections assumed are shown by Drawing D.SD.07, kerbs and channels are shown by Drawing D.SD.06, for the following situations: •
roads with sidewalks and raised (barrier) kerbs;
•
roads with forecourts or shoulders,
•
roads with grass verge, and PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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roads on side-long ground (along the contours).
18. Gully inlets will be used principally with kerbs because the kerbs control and direct the flow towards the gully. They will also be used with dish drains, or in a channel at the edge of a road where a forecourt slopes towards the road. Where there are grass verges there is opportunity to dispose of road runoff by infiltration, and to use swales if the verge is of sufficient width (SUDS compliant). Excess runoff can be collected in open drains or ditches towards the back of the verge. On side-long ground the drain should be on the up-slope side with the road cross-fall towards the hillside. 19. Minimum cross-falls are required to shed water from the road surface. Cross-fall also controls the number and spacing for road gullies. The minimum cross-falls required are at Clause 7.5.7 Table 3 of the Code of Practice. In summary minimum cross-fall is 2.5% for longitudinal gradients between 1% and 5%. For flatter areas or longitudinal gradients greater than 5% the minimum cross-fall should be 3%. A fall of 1 in 40 is commonly used for sidewalks. These cross-falls are within the envelope generally adopted for road design. 4.
Hydrology
20. Drainage design requires the rainfall intensity for different duration and return period. These have been synthesised based on historic rainfall records and are presented as rainfall intensity-duration-frequency (IDF) curves and tables at Appendix 2 of the Drainage Code of Practice. For consideration of climate changes effects and projected increasing frequency of high intensity rainfall the projected corresponding curves and tables for year 2060 are presented at Appendix 4 of the Code of Practice. The 2060 curves are based on transposition of climate model predictions for other pacific islands. 5.
Drainage design
21. The Rational Method1 has been used for all drainage design. The Rational Method and design considerations are described at Clause 6 and elaborated at Appendix 1 of the Code of Practice. The Rational Method is an iterative hand calculation but can be written as a spreadsheet to quickly arrive at the optimum solution; use of the spreadsheet also reduces the errors that might occur during iteration. Preliminary design spreadsheets for each sub-project are in the volume Component 1; Calculations. 22. Flow calculation is based on the Colebrook-White Equation assuming a minimum sand roughness k = 0.6 mm2. 23. Specialist computer design software was not used because it is not necessary for the small and simple catchments found around Port Vila. The use of such software would not realise any savings in capital cost because pipes are selected based on minimum standard sizes and the need to achieve a minimum self cleansing velocity of 1.5 m/s. Taken together these two factors result in all drains having capacity greatly in excess of the design runoff. Moreover, specialist software would have to be accessible and understood by users after completion of the PPTA whereas by following the guidance of the Code of Practice any competent person can prepare calculations using the Rational Method.
1
2
Numerous sources, good relevant guidance is in Watkins LH and Fiddes D, Highway and Urban Hydrology in the Tropics, Chapter 9, Pentech Press, Plymouth, UK, 1984. Sewers for Adoption 6th Edition, A Design and Construction Guide for Developers, Water UK/Water Research Centre, Swindon, UK, March 2006. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Pipe material
24. The design is not sensitive to pipe material and cast or spun concrete, vitrified clay, or plastics pipes including thin wall ribbed plastics can be used. The final selection can be open until detailed design or contractor competitive tender for implementation. 25. Pipe material affects the depth of pipe trench. Concrete pipes may be laid directly onto the bed of the trench and backfilled with selected excavated material. Plastics pipes, because they have annular flexibility must be surrounded 150-200 mm by a course graded granular material which allows the pipe to flex. This requires a deeper trench and imported material. 26. Minimum pipe cover for roads and verges is 1.2 m but can be reduced to 0.6 m under open ground not accessible to vehicles3. In some trafficked locations cover has been reduced to an absolute minimum of 0.6 m in order to achieve minimum velocities of 1.5 m/s, or where this cannot be achieved the highest flow velocity possible. When cover is reduced under roads and verges the pipe will require additional protection such as concrete surround. In broad terms this applies to all pipe materials but some refinement can be considered during detailed design. Indicative pipe trench, bedding and surround requirements are shown by Drawing D.SD.05. 27. There has been much debate in the construction industry spanning several decades on the relative merits of rigid pipes (concrete and vitrified clay) and plastics pipes. It is hard to find impartial opinion since much of the published information comes from the manufactures or trade association whose interest is to promote use of a specific type of pipe. It is also difficult to determine comparative cost because these change between location and the requirements of different projects. On average concrete pipes can cost more initially but plastics pipes require deeper trenches and special fill. All other things being equal plastics can be cheaper for smaller diameters but the advantages switches to concrete for larger sizes. Yet the differences can be marginal and are in no way fixed. In Port Vila availability and shipping costs are further factors, the shipping volumes will be lower for plastics (because pipes can more easily be nested) but concrete pipes plus precast manhole rings and gully pots could be manufactured locally. For this reason no fixed recommendation has been made for pipe material at this preliminary design stage instead it is left to market forces at the implementation stage to decide. The basic design will not be changed by the pipe material and the unit rates used in the costs estimates assumes that for Port Vila the difference in cost of drain pipe materials when laid is marginal and therefore has not been explicitly taken into account. 28. A further consideration is flexibility. Although concrete pipes are classed as ‘rigid’ this is in the annular sense, longitudinally they come with flexible spigot and socket joints (typically every 1.25 m up to 2.5 m)) for allowing movement up to several degrees at each joint. In contrast plastics pipes can bend longitudinally. These are especially relevant considerations given the high incidence seismic activity around Port Vila. Concrete pipes are inherently stronger than plastics but it can be concluded that either type of pipe could be damaged if there was significant displacement of the ground. In such cases damage will be at discrete locations which might require relaying of the drain whatever material is used. 29. Many manufactures of concrete pipes do not list diameters less than 300 or 225 mm, vitrified clay or plastics pipes are more commonly used for these smaller diameters.
3
Technical Guide No 1, - System Design, Section 1.2.2, Concrete Pipeline Systems Association, Leicester, UK, October 2006. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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30. In summary at the implementation stage either concrete or plastics pipes may be chosen. 7.
Pipe sizes
31. Nominal pipe diameters 150, 225, 300, 400, 500 and 600 mm have been assumed for design. These are preferred sizes in European Harmonisation. However the design is not sensitive to the use or substitution of the nearest classic sizes 200, 250, 375, 450 and 525 mm. 32. The smallest pipe size used is 150 mm diameter; the largest size is 600 mm diameter. The majority of drains are 225 and 300 mm diameter. The 150 mm diameter is used for gully connection to carrier drains, this being the standard size for proprietary gully pots. This pipe size is also used at the head of some drain networks where flows will be very small and slopes generally good. Since water only enters the pipe drains through grated gullies, or potentially and occasionally a screened inlet, litter will not enter the pipe drains. The risk of blockage of 150 mm diameter pipes has in every case been considered and is deemed to be not significant where their use is proposed. 8.
Manholes and catchpits
33. Indicative requirements for manholes and catchpits are shown by Drawing D.SD.01, ancillary details for backdrop and Ramp Inlet, and rocker pipes are shown by Drawing D.SD.02. These details are based on the requirements set by Sewers for Adoption4. The details assume the use of precast concrete manhole rings and slabs, this form of construction is widespread, and for example similar drawings appear as standard details for New Zealand municipalities. It therefore seems probable, given the number of chambers required, that contractors will favour this method of construction. There is however nothing to preclude the use of in-situ construction or plastic liners surround with concrete. 34.
Manholes have been classified according to depth to pipe soffit: •
Type A: 3.0 to 6.0 m deep.
•
Type B: 1.5 to 3.0 m deep
•
Type C: up to 1.5 m deep.
As previously mention a catchpit substitutes a sump to capture sediment for the half channel pipe of a standard manhole. 9.
Gully design
35. Indicative requirements for road gully Types R, K and W are shown on Drawing D.SD.03, direct gully connection to a carrier drain pipe is shown by Drawing D.SD.02. The design procedure for determining the spacing and type of road gully is at Clause 7.5 of the Code of Practice. A gully fulfils two purposes: 1. The primary purpose is to effectively remove runoff from the road surface. 2. The secondary but still very important purpose is to trap debris and sediment
4
Sewers for Adoption 6th Edition, A Design and Construction Guide for Developers, Water UK/Water Research Centre, Swindon, UK, March 2006. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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36. There must be sufficient gullies to remove the runoff. Good practice is to place gullies at regular intervals to limit the width of flow against the kerb and prevent water spreading across the road into the track of vehicles. It is important not to simply placing a gully at the low point where water ponds, there must be gullies spaced between the top and bottom of the slope. International practice was researched to find a simple design procedure appropriate to Port Vila. Australian practice has been judged unsuitable, not catering well for the hilly terrain or type of rainfall. Cities such as Singapore and particularly Hong Kong have good guidelines and have similar occurrence of extreme rainfall (typhoons in Hong Kong are the same as Cyclones in Port Vila). Hence the Code of Practice is based upon the Hong Kong methods. 37. Hong Kong Road Note 6 was used as the base reference.5. Road Note 6 is in turn based on UK TRL reports6,7,8. There is more recent research on this topic but it focused on major highways and the simple charts in Road Note 6 make it a suitable and easily applied methodology. 38. The rule of thumb for gully spacing is that there must never be less than one gully for every 25 m of road or 100 m2 of drained road area. Generally the requirement is for more gullies than the minimum, especially on steep roads or flat areas (slope 3.0 ha in area for Anabrou, 2.0 ha in area for Ohlen. The sinkhole depression within PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Anabrou has a low point about 39.1 m MSL but the main access road which skirts it is at 40.5 m MSL at its lowest point. There are several side streets crossing the depression and permanent residences within the depression. The valley catchment is about 0.44 km2 defined to the west by a ridge rising to 66 m MSL and the east by a ridge rising to 80 m MSL. 153. The Ohlen sinkholes have a floor level a little over 40 m MSL. Between each sinkhole the valley floor is 44 m MSL where it is directly over Limestone and where the road passes through the depression it has been raised to a minimum elevation 40.7m MSL and is therefore higher than adjacent property. The valley catchment is about 0.58 km2, defined to the west by several conical hills rising to 67 m MSL and the east by a ridge rising to 85 m MSL. The subdivision is fully occupied with a grid pattern of streets and established properties in the southern part but in the north there is more informal housing. The steep slopes mean that the drainage requirement is probably approaching the ultimate future requirement although there will be a further increase as roads are paved and higher standard properties are built. 154. During heavy rainfall runoff flows down the steep side roads and floods the depressions and the main access road where this crosses them. In the steep side streets the uncontrolled flow is causing erosion and fretting of sealed pavement where these exists, this would be more severe were it not for the shallow depth to rock. At the depression in Ohlen where the road is frequently flooded the main access road has been raised and provided with drain channels and soakaway pits but these have no effective outfall, very quickly block with silt and therefore do not mitigate the flooding. Because the property beside the road is lower than the road; in Ohlen the occupants have built walls and dams across gateways but still suffer flooding when there is too much water, which is often. 2.
Description of sub-project
155. Drawing D.SSA.PLAN illustrates the drainage sub-project proposals for Seven Star Anabrou. 156. During Phase I it was thought that Seven Stars would be drained 43% to the Anabrou and 57% to the Ohlen outfalls but it was noted that this proportion might change when more topographic survey information had been gathered for detailed design. This proved to be the case and the proposals here drain 80% to Anabrou and 20% to Ohlen outfalls. The reason is that Drains 1.07 and 1.08 which cross the ridge to above Fatumaru Bay run along a street which was lowered in elevation by the Public Works Department in 2009. This significantly reduces the depth of excavation required for pipe trenches from that which would have been needed had the natural ridge levels remained. The change in the areas drained also reduces the combined capital cost for the two Seven Stars catchments by more than $500,000. 157. The sub-project will provide channel and pipe drains to outfall via Lini Highway into Fatumaru Bay. A 400 m long carrier drain is required to reach the outfall but this mostly follows existing roads moving downhill and will provide local drainage for 0.16 km2 on the way. The carrier will also provide drainage for a 425 m length of Lini Highway. There will be a need for sections of pipe trench in the depth range 4.0 to 6.0 m over about 250 m length in order to drain two of the sinkholes and cross the intervening ridge to Lini Highway. There is limited opportunity for SUDS in streets which run down the slope because the gradient is too steep and the flow velocity too high. 3.
Justification for sub-project
158. The justification for this sub-project is elimination of the repeated flooding of roads and property. The flooding causes disruption, physical damage to infrastructure and property, is a
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health and safety hazard and causes public dissatisfaction. Provision of channel drains on steep side roads will control the erosion. 4.
Design proposal
159. In addition to Drawing D.SSA.PLAN the proposals are illustrated by accompanying Plan Profile drawings of the principal drains and schedules of manholes and gullies. 160. Drain 1 runs north and drains the valley and side roads for Anabrou as far as Manhole 1j where Drain 11 from Ohlen connects. The minimum velocity of 1.5 m/s is achieved and exceed. Moreover where the drain passes the sinkhole with a low point 39.1 m MSL the drain invert is lower than the ground falling from 38.14 to 36.95 m MSL and will allow the depression to drain by gravity. 161. The southern most and most frequently flooded of the two depression in Ohlen is also drained together with the roads which drain towards it. Drains 12.03, 12.04 and 12.05 pass through the depression and connect via Drain 11.03 to Drain 1 at Manhole 1j. It is possible to have enough falls to achieve velocities exceeding 1.5 m/s in these critical sections of drain. Drains 12.04 and 12.05 have inverts between 40.50 and 36.25 m MSL and will allow properties within the depression to drain by gravity. Unfortunately the distance and depth of excavation required to capture the drainage for the second sinkhole just to the north make it not cost effective to include this in the Seven Stars Anabrou catchment although connection by ditches might alleviate problems in the short term if the two sub-projects are built at different times. 162. Generally the steepness of the side roads and the shallow depth to rock requires the use of concrete channel. Channels are essential to contain what will be supercritical flow and prevent it spreading across the road. Dish drains have been proposed for the few flatter streets which run along the contours. The final sections of Drains 7 and 9 are pipe drains to allow the Anabrou sink hole to drain by gravity. 163. Currently most side roads are unmade, or in very bad condition requiring reconstruction. These roads must be properly constructed before the drains will work. This particularly applies for roads followed by Drains 1, 11.03, 12.03, 12.04 and 12.05. In recognition that most of the roads on the hill slopes will remain unmade for some years to come the construction of drainage channels in these roads has been excluded from Component 1 and the channels should instead be included with future road works. 164. From Manhole 1j Drain 1 takes the shortest route to outfall at Fatumaru Bay. It is necessary for an easement to cross private land east of Lini Highway. The final section to the outfall also crosses private land but where there is an exiting outfall. Because of the drop there is no problem with outfall elevation which can be set at 1.9 m MSL to minimise tide locking for the life of the drain. But the steep drop also means an energy dissipator will be needed; a standard USBR Type VI enclosed impact basin would be suitable. 5.
Quantity and cost estimates
165. The estimated principal quantities for Seven Stars Anabrou are presented with the Component 1: Calculations. It is assumed that a high proportion of the deep pipe trench will have extra-over cost for rock excavation. The quantities for gullies include allowance for 4 m length of 150 mm diameter pipe to connect to the carrier drain and are not listed separately. 166. The cost estimate excludes preliminary and general items for the capital cost. It includes for road reinstatement of trench excavation but not bringing roads up to standard PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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(reconstruction of the road pavement or resurfacing, cross-fall, kerbs and sidewalks, etc). Summary quantities and costs for upgrading drainage works for the full catchment including currently unmade roads are in Table 9. Table 9 - Summary quantity and cost estimate for Seven Stars Anabrou for full sub-catchment drainage
Item Channel drain Pipe drain Chamber Road gully
Quantity 4,716 2,613 58 291
Unit m m nr nr Total
Cost $224,000 $382,000 $168,000 $200,000 $974,000
Cost per km2 drained $1,136,000 167. Summary quantities and costs for the sub-project proposed under Component 1 (excluding unmade residential roads, paragraph 163) are in Table 10. Table 10 - Summary quantity and cost estimates for Component 1 sub-project for Seven Stars Anabrou
Item Channel drain Pipe drain Chambers Road gully
J. 1.
Quantity Unit 1,043 m 2,021 m 46 nr 286 nr Total
Cost $56,000 $296,000 $112,000 $199,000 $663,000
Seven Star (Ohlen)
Description of existing situation
168. It is explained at section I that Seven Stars straddles two catchments Ohlen and Anabrou but with a common problem. The catchments have different outfalls which cannot be combined due to the topography and therefore require separate sub-project solutions. 169. In addition to the description at section I and paragraph 153 the northernmost sinkhole at Seven Stars Ohlen is 0.4 m2
0.2 to 0.4 m2
< 0.2 m2
0.5 m
1.5 m
1.85 m
≤ 1%
0.03
0.06
0.11
0.13
0.18
0.14
1% to 5%
0.05
0.10
0.18
0.21
0.29
0.23
5%
0.08
0.14
0.25
0.29
0.4
0.32
≤ 1%
0.03
0.05
0.09
0.11
0.17
0.14
1% to 5%
0.04
0.08
0.15
0.17
0.27
0.22
5%
0.06
0.11
0.20
0.24
0.38
0.31
Gradient
Note: A reduction factor 0.03 corresponds to an efficiency 97%, and so on.
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It should be noted that the most efficient arrangement of grating is diagonal not transverse. However installing a gully grating with a diagonal pattern to the wrong orientation reduces the efficiency by about 20%. The correct orientation is shown in Figure 2. The gully efficiencies in Table 4 and also the formulae for the calculation of gully spacing described above are based on the arrangement with single gully assemblies at each gully location. The provision of double gullies at every location is in general not cost effective as there is little effect in increasing gully spacing, notwithstanding the recommendations at clause 7.5.15 and clause 7.5.16. Figure 2 - Specified Grating Orientation
Kerb
Direction of flow
Road
7.5.13. Blockage by debris All grating designs are susceptible to blockage by debris, especially for flat gradients in the urban areas and road sections adjacent to amenity or landscaped areas. Some allowance should therefore be made in the calculated spacing for the reduction in discharge. An appropriate reduction factor on the discharge should be made according to the local conditions. As a general guidance, reduction factors should be applied as described in the following Table 5. Table 5 - Reduction Factors for Blockage by Debris
Road characteristics longitudinal gradient less than 0.5%
longitudinal gradient 0.5% or more
RFdebris 0.80
near sag points or blockage black-spots, e.g. streets with markets or hawkers
0.80
near amenity area
0.80
other sections
0.85
Note: A reduction factor 0.80 corresponds to 20% blockage, and so on.
7.5.14. Locations requiring kerb gullies Kerb gullies have an overflow weirs in the face of the kerb which serve two functions. •
Firstly the vertical opening is a kind of kerb inlet and would provide additional drainage path under normal circumstances. This is useful in roads with moderate or steep gradient where the higher flow velocity enables a certain amount of surface water to by-pass the gully through the very narrow inner edge of gully assemblies. The provision of overflow weirs on roads with moderate and steep gradient is recommended as they remove the inner edges and also provide additional inlet openings.
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Secondly the arrangement provides a reserve inlet for surface water in case the gully grating is obstructed by debris. The reserve inlets are necessary on flat roads and sag points, including blockage black-spots, where the likelihood of debris collecting on gratings and along channels is high.
Kerb gullies shall be provided on roads with longitudinal gradient less than 0.5% or greater than 5%, or at sag points/blockage black-spots according to Table 6. The drawback of kerb gullies is that they provide yet another passageway for debris to enter the gully pot which may eventually cause blockage of the gully. It is therefore important to provide bars across the vertical opening to reduce the size of the openings and to prevent the entry of large particles. Where provided on roads with moderate or steep gradient, the bars should be horizontal or parallel to the length of the weir so as to maintain drainage efficiency. Where provided on flat roads or sag points, the bars should be vertical as this arrangement is more effective in preventing entry of debris. Table 6 - Minimum rate of provision of kerb gullies
Road characteristics
Minimum Rate of Provision of kerb gullies
longitudinal gradient > 7%
Every other gully
longitudinal gradient > 5% but not more than 7%
Every third gully
longitudinal gradient between 0.5% and 5% inclusive
No kerb gullies
longitudinal gradient < 0.5%
Every third gully
Sag points or blockage black-spots.
Every gully
7.5.15. Double gullies Although provision of double gullies is in general not cost effective in increasing gully spacing as is mentioned at clause 7.5.12, they are considered beneficial in reducing the severity and the chance of blockage on gully grating by debris. Therefore, double gullies are recommended to be provided at locations suspected to be blocked by debris easily or at locations with change in gradient.
7.5.16. Gullies at sag points (minimum triple gullies) Sag points can be the trough at the bottom of a hill or locally at bends created by superelevation. Any surface water not collected by the intermediate gullies will end up at the sag points. It is therefore important to provide spare gully capacity at sag points. A minimum of three gullies should be provided on all sag points. The first one collects surface water from one side of the trough, the last one collects surface water from the other side, and the middle gully (gullies) provides spare capacity. The catchment area is the road area such that runoff flows towards the sag point. For hilly locations the catchment area of a sag point could be very large. Note that surface water always follows the line of greatest slope rather than confined to one side of the carriageway. Hence when there are gullies at both sides of a road at a sag point, very often the two sets of gullies have catchment areas quite different in sizes unless the catchment area is a straight road with camber throughout. If the catchment area concerned becomes larger, there is a higher chance for a certain amount of surface run-off bypassing any blocked intermediate gullies and eventually reaching the sag point. In such circumstances, surface water may accumulate at the sag point and cause flooding and hazard to traffic. In view of this, it is necessary to provide additional gullies at sag points to reduce the likelihood of such occurrence. It should be PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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borne in mind, however, that the key for the proper functioning of the surface drainage system is the proper maintenance and clearance of blocked gullies rather than the addition of gullies. The number of additional gullies to be provided at sag points is affected by: (a) the likelihood of intermediate gullies being blocked; (b) the size and layout of the catchment area; (c) the relative importance of the road and the consequence of flooding; and (d) the presence of alternative outlets (perhaps at a slightly higher level). As a general guideline, additional gullies should be provided at sag points based on the size of the catchment area in accordance with Table 7. Table 7 - Additional Gullies at Sag Points
Catchment area (m2)
Number of Gullies at Sag Points
< 600
3
600 - 1,999
4
2,000 - 3,999
5
4,000 - 5,999
6
6,000 - 9,999
7
10,000 - 14,999
8
15,000 - 19,999
9
> 20,000
10 for the first 20,000 m2, plus one for every extra 5,000 or less m2
7.5.17. Gullies immediately downstream of moderate or steep gradients On roads with moderate or steep gradient, surface water follows the line of greatest slope and flows obliquely towards the kerb side channel. There is no significant effect on the size of the drained area if it is a constant gradient or a gradual transition. However, if the road suddenly flattens out, the surface water bypassing the last gully on the steep section may overload the first few gullies on the flatter section due to the oblique flow. Provision should be made to intercept such oblique flow when a road with moderate or steep gradient flattens out. As a general guide, the first 3 sets of gullies immediately downstream of a road section of longitudinal gradient 5% or more should be double gullies rather than single gullies. Also, adjacent gullies should be located at least one kerb length apart so that the portion of pavement between them can be properly constructed.
7.5.18. Drainage at steep road junction On roads with steep longitudinal gradient, surface runoff follows gravity and runs in a diagonal path. When a steep road joins another road at a junction, a portion of runoff cannot be intercepted by the last gully on the steep road and will overshoot pass the road junction (Figure 3). Additional drainage load is therefore carried over from the steep road to the road junction and may cause flooding there. To collect the runoff from the additional catchment area, additional drainage has to be provided at the road junction. For simplification, additional gullies at the opposite side of the steep road are advised as shown in Figure 3. The guideline for the provision of the additional gullies is similar to that at sag points as mentioned in clause 7.5.15 and Table 7. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Whenever the designer considers that provision of additional gullies is not appropriate due to site constraint or other reasons, provision of transverse drain at the end of the steep road may be considered. In such case, the transverse drain may be in the form of grated channel with adequate capacity to drain runoff under the ultimate state (i.e. the 1 in 10 year 5 minute duration rainfall). Figure 3 - Additional Catchment Area at Road Junction
7.5.19. Footway drainage In general footways should have a cross-fall towards the kerb to allow surface water to be collected by the kerb side gullies on the carriageway. The total width of footway and carriageways should be used in determining the drained width. Where the paved area adjacent to the carriageway is very wide, gullies at a very close spacing along the carriageway may be required. In such case, it may be more appropriate to provide a separate drainage system for the footway. One option for footways in rural areas with low pedestrian volume is to drain surface water to separate open or covered channels at the back of the paved area.
7.5.20. Pedestrian crossings At pedestrian crossings where there are many pedestrian movements across the kerb side channel, it is worthwhile to spend extra effort in detailing the position of gullies to minimise inconvenience to the pedestrians. It is recommended that: (a) no gully should be located within the width of any pedestrian crossings; (b) for roads of longitudinal gradient 0.5% or above, a gully should be located at the upstream end of all pedestrian crossings; and (c) for roads of longitudinal gradient less than 0.5%, another gully (in addition to that required under (b)) should be provided at the downstream end.
7.5.21. Continuous drainage channel For wide carriageway roads in flat areas or flood prone areas, gullies would need to be provided at very close spacing. In such circumstances, drainage by means of covered PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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continuous channels may be preferable. However, the susceptibility of damage by vehicles and the maintenance effort required should be considered thoroughly if continuous channel is proposed to be used.
7.5.22. Gully pots Gullies without water seal oil traps are preferred because they are less susceptible to choking. Water seal oil trap gullies should be used when there is the possibility of having discernable concentrations of hydrocarbons discharged into the storm water drain serving the gullies (note high risk areas should be provided with oil interceptors, see clause 9). Precast or preformed gully pots should be used instead of in-situ construction except in special cases where physical or other constraints do not allow their use. The following are some of the advantages of using precast or preformed gullies: (a) easier to install and maintain; (b) smooth internal finish which allows easy cleansing (debris tends to adhere to rough in-situ concrete or blockwork walls); and (c) where outfall trapping is required, the obvious choice is precast trapped gully pot as it is extremely difficult to build an acceptable trapped gully by in-situ construction.
7.5.23. Y-junction connection Gully outlet pipes should be properly connected to carrier drains. The connection should be formed by means of either a manhole or a Y-junction/saddle connection fitting wherever practicable. Connecting an outlet pipe through an opening in an existing drain shall be avoided as far as practicable. Under extreme circumstances where connection of gully outlet pipe through an opening in an existing carrier drain is the only choice, the following measures shall be strictly followed: (a) A detailed proposal of the works should be submitted to the Public Works Department for agreement prior to execution of the works; (b) A short concrete pipe of maximum length 500 mm should be used for connection to carrier drains. Flexible jointing should be adopted for the gully pipes in these circumstances. The 500 mm length restriction is not required for PVC gully pipes; (c) Opening up of existing carrier drains must be handled with extreme care; over breaking shall be avoided; (d) The section of the carrier drain at the connection point shall be surrounded by insitu concrete of at least 150 mm thickness, to a length of not less than 300 mm along the carrier drain on each side from the circumference of the opening. To control cracking, the surrounding concrete should be reinforced; (e) Upon completion of the connection works and final set of the surrounding concrete, the inside of the existing carrier drain shall be inspected either by direct visual inspection or by using CCTV to check for imperfections such as cracks, over breaking, intrusion of surrounding concrete, protrusion of gully outlet pipe, etc. Defects detected shall be made good either manually or by means of remote controlled device if necessary. Gully pipe protrusion must be cut to flush with the internal wall of the carrier drain; and (f) Details of the as-built works, checking certificate and CCTV record (for pipes too small to be entered by inspectors) shall be submitted to the Department of Public Works within one month upon completion of the works for record purpose.
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8. Soakaway Pits 8.1. Circumstances suitable for soakaway pits In principle the use of soakaway pits is desirable because they comply with the objects of SUDS by maximising recharge to groundwater and reducing peak runoff to surface water drains. Many locations in Port Vila are suitable for soakaways because of the underlying and highly permeable Coral Limestone rock. Therefore, soakaways are a good solution to be encouraged for individual plots and small developments. However soakaways are a less desirable means of surface water drainage for roads or more extensive sub-division catchments. This is demonstrably the case because of the poor success rates of soakaways in such locations. When they have been tried in response to specific flooding problems they have not provided a longer-term sustainable solution, they are neglected and quickly clogged with silt and since they are not well designed become overwhelmed during large rainfall. It is acceptable to use soakaways in combination with other SUDS measures but low places where roads and sub-division drainage collect require positive surface water drainage, preferable by gravity.
8.2. Road gully direct connection to soakaway Not withstanding the comments in clause 8.2 there will be occasions when it is cost effective to have a direct connection of an individual road gully to a soakaway chamber. In these cases there shall be a separate soakaway for each separate gully pot. The gully spacing shall be determined in compliance with clause 7.5 including the limitations that the gully spacing must not exceed 25 m and the maximum area draining to the gully is 100 m2. Additionally adjacent soakaway gullies must be a minimum 20 m apart. The soakaway chamber shall have a closed access cover for inspection and maintenance. It is noted that provided the sump in the gully pot is regularly emptied of silt then the soakaway chamber will require little or no maintenance.
8.3. Disposal to soakaway pit Where surface water drainage is to be discharged to a soakaway pit, the suitability of the natural ground to receive and dispose of the water without causing damage or nuisance to neighbouring property, or damage to the environment or groundwater resources, shall be demonstrated to the satisfaction of the Public Works Department.
8.3.1. Infiltration test An infiltration test shall be required at the site of the proposed soakaway. The requirement for the test may be waived at the discretion of the Public Works Department if the general location is known and recognised as suitable for this method of disposal. The infiltration test shall be carried out as follows: (a) Bore test holes of 100 mm to 150 mm diameter to the depth of the proposed soakaway. If groundwater is encountered in the bore test hole then this depth shall be taken as the depth of the soakaway. (b) Fill the hole with water and maintain full for at least 4 hours, (unless the soakage is so great that the hole completely drains in a short time). (c) Fill the hole with water to within 750 mm of ground level, and record the drop in water level against time, at intervals of no greater than 30 minutes, until the hole is almost empty, or over 4 hours, whichever is the shortest.
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(d) Plot the drop in water level against time on a graph, and the soakage rate in mm/hr is determined from the minimum slope of the curve. If there is a marked decrease in soakage rate as the hole becomes nearly empty, the lower rates may be discarded and the value closer to the average can be adopted.
8.3.2. Design of soakaway The soakaway shall be designed utilising soakage and storage in accordance with 9.0.5 and 9.0.6 to ensure that surface water is discharged without overflowing. The rainfall intensity used in the design of the soakaway shall be that for a 1 in 10 year 1 hour duration rainfall using the appropriate rainfall intensity-duration-frequency curves in Appendix 2. The soakaway shall comprise either a rock filled hole or a lined chamber (for a road gully clause 8.2 a chamber shall be used). Both of these options shall be enclosed in filter cloth complying with AS 3706.1. The filter cloth shall have a mass per unit area of 140 g/m2 and a minimum thickness of 0.45 mm. The volume of storage required in the soakaway shall be calculated from the formula:
Vstor = Rc − Vsoak Where
Vstor =
Volume of storage required (m3)
Rc =
run-off discharged from catchment to soak pit in 1 hour (m3)
Vsoak =
volume disposed of by soakage in 1 hour (m3)
and
Rc = 10CIA Where
C=
run-off coefficient (same as Rational Method, see Appendix 1).
I=
Rainfall intensity for 1 in 10 year 1 hour rainfall (mm/h).
A=
area of the catchment discharging to the soakaway (ha)
and
Vsoak = Where
Asp S r 1000
Asp =
area of the base of the soakaway (m2)
Sr =
soakage rate determined from infiltration test (mm/h)
Where the soakaway comprises a rock filled hole then the volume available for storage, Vstor, shall be taken as 0.38 times the volume of the hole.
9. Separators 9.1. Introduction Surface water drains must discharge to the sea, a watercourse or indirectly into underground waters (groundwater) via a soakaway. Contamination of surface water by oil, chemicals or suspended solids can cause these discharges to have a serious impact on the receiving water. The bays and lagoons surrounding Port Vila are environmentally sensitive waterbodies requiring the highest practical level of protection against pollutants.
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There is a range of means of dealing with such pollution both at source and at the point of discharge from site (so called ‘end of pipe’ treatment). These techniques are part of SUDS. Where run-off is draining from relatively low risk areas such as car-parks and non-operational areas, a source control approach, such as permeable surfaces or infiltration trenches, may offer a suitable means of treatment, removing the need for a separator. Otherwise one of the methods described below is required.
9.2. Oil separators general Oil separators are installed on surface water drainage systems to protect receiving waters from pollution by oil, which may be present due to minor leaks from vehicles and plant or from accidental spillage. Effluent from industrial processes and vehicle washing should normally be discharged to the foul sewer, when one exists, for further treatment at a municipal treatment works. Otherwise it must be stored and tankered to safe disposal.
9.2.1. How oil separators work Oil separators can be fitted to surface water drainage systems to protect the environment from pollution by oils. They separate the oil from the water, and then retain the oil safely until it is removed. They are installed to contain oil leaks from vehicles and plant and accidental spillages. To be effective, oil separators need to be correctly designed, installed and maintained.
9.2.2. Where separators are needed Surface water may be contaminated by oil at a number of different sites. These sites need to have measures in place to prevent this oil from polluting the environment. These sites include: •
car parks typically larger than 800 m2 in area or for 50 or more car parking spaces;
•
smaller car parks discharging to a sensitive environment;
•
areas where goods vehicles are parked or manoeuvred;
•
vehicle maintenance areas;
•
roads;
•
industrial sites where oil is stored or used;
•
refuelling facilities; and
•
any other site with a risk of oil contamination.
Gully pots with trapped water seals can provide adequate protection for car parks that are too small to justify the installation of a separator, but they must be properly maintained.
9.3. Purpose built separators It is perfectly possible to construct oil separators in-situ and worldwide there are various government agencies and organisations which have designs for standard types. However, for the small and limited applications in Port Vila prefabricated separators are recommended, this is for performance and efficiency as described in clause 9.4. If the decision is made to construct a purpose built separator then calculations and drawings must be provided in advance to the Public Works Department for approval together with details of the guaranteed standard of treatment.
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9.4. Prefabricated separators Prefabricated separators generally come as GRP or rotomoulded units complete with all pipe work and fittings with guaranteed performance for a specified flow range. They are simply lowered in a prepared excavation with bedding and concrete surround according to the manufacturer’s instructions and then connected to the drain inlet pipe work and outfall. Prefabricated separators should comply with European standards EN 858-1 and 858-2 or equivalent. The standard refers to two ‘classes’ of separator, based on performance under standard test conditions. Class I separators: are designed to achieve a discharge concentration of less than 5 mg/l of oil under standard test conditions. These separators are required for discharges to surface water drains and the water environment. Many Class 1 separators contain coalescing devices, which draw the oil droplets together and facilitate the separation. Class II separators: are designed to achieve a discharge concentration of less than 100 mg/l of oil under standard test conditions. They are suitable for dealing with discharges where a lower quality requirement applies such as discharges to the foul sewer. Both classes can be produced as ‘full retention’, ‘bypass’ or ‘forecourt’ separators (see below). The oil concentration limits of 5 mg/l and 100 mg/l only apply under standard test conditions. You should not expect separators to always perform within these limits under field conditions. In addition, these levels of oil might be too high in some environmentally sensitive areas to allow the discharge to pass into the water environment without additional treatment.
9.4.1. Full Retention Separators Full retention separators treat the full flow that can be delivered by the drainage system. The ‘full flow’ is normally equivalent to the flow generated by a rainfall intensity of 65 mm/h Full retention separators are used where there is a risk of regular contamination with oil and a foreseeable risk of significant spillages e.g. vehicle maintenance areas and retail fuel forecourts. It is necessary to consider the flow rates of potential spillages delivered to the separator from the drainage system and the oil storage volume of the separator needs to be sufficient to retain the entire spillage. On large sites, some short-term storage upstream of the separator might be an acceptable means of limiting the flow rate and the size of separator needed. Any surface water stored cannot be pumped through the separator unless the separator is specifically designed to receive pumped inflows and a low-shear, non-emulsifying pump is used.
9.4.2. Bypass Separators Bypass separators fully treat all flows, for the area served, generated by rainfall rates of up to 6.5 mm/h. Flows above this rate are allowed to bypass the separator. These separators are used when it is considered an acceptable risk not to provide full treatment for high flows, the circumstances and rationale being: •
where only small spillages can occur and the risk of spillage is small such as on short stay car parks; and
•
a small spill of pollutant on the ground is carried by the first flush of rainfall into the treatment chamber and is no longer present to pollute subsequent runoff.
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In cases where a large spillage might occur, it is not acceptable to use a by-pass separator. The exception to this is public roads where the size and type of spillage is impossible to foresee and the surface area drained makes it impractical to provide a full retention separator. On sites where high levels of silt are likely to enter the separator, the build up of silt must not be allowed to compromise the operation of either the separator or the by-pass device. On such sites (e.g. quarries) an adequately sized silt separation chamber should be installed upstream of the separator and appropriate management systems put in place to monitor the situation and remove the silt when necessary. The use of SUDS techniques can minimise the amount of silt in the surface water run-off.
9.4.3. Forecourt Separators The term ‘forecourt’ refers to all forms of liquid-fuel dispensing outlets, both retail and nonretail, including those where only diesel is dispensed. A forecourt separator must be a ‘full retention’ separator, large enough to serve the catchment area of the site and have a sufficient oil storage volume to retain any foreseeable spillages. It is important to install a forecourt separator of an appropriate size. On a forecourt where tanker deliveries are received, a separator with an oil storage capacity of 7,600 litres will meet the requirements of BS EN 858-2. If a smaller unit is proposed, the size should be determined by undertaking a risk assessment incorporating catchment size, potential spillages during delivery, and other risks such as safety issues. If the compartment size of the tanker that delivers to your site is greater that 7,600 litres the separator should be sized accordingly.
9.4.4. Selecting the Right Separator Figure 4 gives guidance to aid selection of the appropriate type of separator for use in surface water drainage systems which discharge into the sea, watercourses or soakaways.
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Figure 4 – Selection chart for the appropriate type of separator
9.5. Separator size 9.5.1. Nominal size Prefabricated separators tested in accordance with the standard test procedure in the European Standard are allocated a nominal size (NS) on the basis of the test results. Full retention and bypass separators are referred to as NS and NSB, respectively. The nominal size of a full retention separator that is required for a catchment area A (m2) is obtained using the formula:
NS = 0.018 × A For a bypass separator, the formula is:
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NSB = 0.018 × A In addition, capacity for silt storage C (litres) must be provided for all separators, either as an integral part of the separator or as a separate upstream unit, according to the formula:
C = NS × 100 or C = NSB × 100 Silt capacity for a bypass separator must be provided either upstream of the separator or in the bypass weir chamber, and not in the main oil separating chamber. Separators must be designed such that when the silt chamber or silt area of the separator is full of silt, this will not affect the operation of the separator, the skim pipe or the by-pass device.
9.5.2. Oil storage capacity The oil storage capacity is defined as the volume of separated oil that can be stored in the separator without any of the stored oil entering the inlet or outlet of the separator. The oil storage volume V (litres) is given by the formula:
V = NS × 10 or V = NSB × 15 On sites where significant oil spillages are foreseeable, make sure the oil storage capacity is sufficient to retain any such spillage and a separator larger than that identified in clause 9.5.1 may be required.
9.5.3. Minimum size The minimum working capacity (which excludes any provision for silt deposition) of a separator should be 1,000 litres; though for forecourts, it is likely that risk assessment will indicate the need for a larger separator. For bypass separators, the minimum capacity is defined as the working capacity of the oil separating chamber only.
9.6. Closure devices and alarms 9.6.1. Closure devices If too much oil is allowed to accumulate inside a separator, it will not work effectively and oil will escape. To avoid this, full retention separators must be provided with an automatic closure device that will prevent flow passing through the separator when the quantity of oil in the separator exceeds the oil storage volume V. Also, during emptying or maintenance the separator should be isolated to prevent the escape of waste oil. Open all isolation valves when the operation is complete. Do not fit automatic closure devices to bypass separators unless they have been designed specifically to operate on such separators. If the automatic closure device is activated the operator should be alerted by a high level alarm so that immediate maintenance can be carried out.
9.6.2. Alarm systems Separators must be provided with a robust device to provide visual and audible warning (if necessary to a remotely located supervisory point) when the level of oil reaches 90% of the oil storage volume V under static liquid level conditions. This automatic warning device indicates that the separator is in need of immediate emptying for it to continue to work effectively. Also, as the build up of silt will prevent the separator from working effectively, it is recommended that a silt level alarm or another suitable device is installed in the separator to PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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alert the build-up of excessive levels of silt. In many cases, oil and silt alarms can be fitted to an existing separator. Silt alarms are most useful on those sites where high volumes of silt are likely to enter the separator, such as quarries and builder’s yards. Further equipment can be fitted to the separator, alongside a closure device and warning device, to alert the site operator to the routine maintenance requirements of the separator. This equipment might, for example, indicate when the next inspection is due and such ‘separator management systems’ will ensure that the separator continues to receive the appropriate level of attention. Any electrical device used within a separator or used to monitor sensors placed within a separator must be intrinsically safe and certified to a suitable explosion protection standard. The location of the monitoring device, such as the alarm or ‘separator management system’ control panel, must be located within a safe area. For this reason it is important to always use qualified technicians who are familiar with the installation, calibration and servicing of intrinsically safe equipment. Regular maintenance and testing of equipment is essential.
9.7. Installation and labelling 9.7.1. Installation Any clean water should be discharged downstream of the separator. If any clean water is drained through the separator, it is necessary to consider this extra water volume when selecting the separator type and size. Provide separators with sufficient access points to allow for the inspection and cleaning of all internal chambers. Keep access to the separator clear and do not use this area for storage. If the separator is installed to retain flammable liquids, provide appropriate ventilation.
9.7.2. Labelling Provide separators with a visible and durable label that can be read after installation and which contains the following information: •
manufacturer’s reference number and
•
oil storage capacity
•
year of manufacture
•
volume of separator
•
bypass/full retention
•
silt storage capacity
•
unique identifier for the design of separator
•
oil level warning device details
•
(name or number)
•
depth of oil storage
•
class of separator
•
closure device details.
•
nominal size
Mark the position of all separators clearly on all drainage plans and identify the separator on the ground by marking the manhole cover ‘Separator’.
9.8. Operation and maintenance 9.8.1. Maintenance during use To prevent pollution and minimise costs, the separator must be managed your effectively. To make this easy, all parts of the separator that have to be regularly maintained must be accessible at all times.
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Every six months, or in accordance with manufacturer’s instructions, experienced personnel should: •
physically inspect the integrity of the separator and all mechanical parts;
•
assess the depth of accumulated oil and silt;
•
service all electrical equipment such as alarms and separator management systems; and
•
check the condition of any coalescing device and replace it if necessary.
A detailed log shall be kept of when the separator is inspected, maintained, emptied and serviced. Also to record specific events relating to the separator system such as cleaning, repairs, accidents and incidents. All separators should be emptied as soon as a significant quantity of oil and/or silt has built up. The retained waste, including the silt, must be removed and the separator must be refilled with clean water before being put back into service to prevent damage and to prevent oil passing through it. In addition to normal emptying of the separator, it will also need to be emptied right away if oil or silt levels exceed 90% of the storage volume of the separator and the alarm is activated. Every five years it is recommended that separators be emptied and given a general inspection to test the integrity and performance of the system. The separator must be refilled with clean water following such an inspection.
9.8.2. Waste management All waste must be handled, stored and disposed of correctly to avoid pollution. Waste oil is designated as hazardous/special waste and disposed of accordingly.
10. Pumped Drainage System 10.1. Scope This sub-section describes the requirements for small pumped drainage systems as might be required for basements at a private development. There is currently no requirement for pumped storm water drainage in the existing and planned Port Vila storm water drainage. Pumping is to be avoided because of the operational and maintenance requirements and recurrent costs. If circumstances arise where pumped drainage is necessary, then this must be dealt with on a case by case basis and is deemed to be outside the scope of this Code of Practice.
10.2. Small pumped drainage system The minimum design and operation criteria for the pumped drainage system shall be as follows: (a) the pumping capacity shall be adequate to cater for immediate discharge of the storm water ingress of not less than 150 millimetres per hour from the entire source catchment area; i.e.:
P> Where
P=
pumping capacity (m3/s)
I=
rainfall intensity (mm/hr)
IA 3.6 × 10 6
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catchment area contributing to ingress of storm water (m2)
(b) there shall be a complete set of back-up pumping equipment, including back-up pumps, pumping mains, generators and their appurtenances for back-up power supply. (c) the pumping installation shall be designed with an automated device to start the pumping operation at times of storm water ingress, with operational option for manual control to override the automated device whenever desired. (d) adequate pump sump shall be provided with sufficient storage capacity to cater for the total quantum of inflow from the entire source catchment area over a duration of at least 3 hours or such longer period as may be deemed necessary by the Qualified Person or as required by the Public Works Department for the reactivation of the pumping installation in the event of emergency breakdown/repairs or power failure, based on the maximum recorded rainfall given below : Duration (hrs) Total Rainfall (mm)
3
4
5
6
12
24
151
211
253
282
377
533
(e) the Qualified Person shall formulate and implement a well-regulated procedure for the maintenance, operation and monitoring of the pumped drainage system. (f) the base of the pump sump shall be designed with a gradient of 1:40 or steeper, and which shall be graded towards the pumps. The pumps shall be located within a small sump pit which should be deeper than the pump sump so that there will be no stagnant water in the pump sump at all times. The criteria specified above are minimum requirements which shall be complied with. Nevertheless, the Qualified Person shall be fully responsible for the complete design of the pumped drainage system, incorporating such additional features or requirements as the Qualified Person may deem necessary to achieve fail-safe protection of the basements, tunnels or underground facilities against flood. The civil and structural components of the pumped drainage system shall be designed and endorsed by a Professional Engineer (Civil) while the mechanical and electrical components shall be designed and endorsed by a Professional Engineer (Mechanical/Electrical). Design computations duly endorsed by the Professional Engineers shall be submitted to the Public Works Department for record including the operation sequence and monitoring measures of the pumped drainage system and other relevant information. The developer/owner shall be responsible for the maintenance, operation and monitoring of the pumped drainage system. The Qualified Persons shall liaise with the developer/owner to ensure that a well-established management set-up is operational to undertake this function before applying for the issue of Temporary Occupation Permit and Certificate of Statutory Completion. The Public Works Department may in special cases introduce amendments or additional requirements for the design and operation of the pumped drainage systems.
11. Aesthetic Treatment of Watercourses The Public Works Department may consider and approve proposals for the development of waterbodies and aesthetic treatment of watercourses. Impacts of such features on the land usage and layouts to the development proposals should be evaluated and planned from the onset of the development proposals. For instance, more land is needed to accommodate a PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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larger aesthetic internal stream instead of a smaller functional drain. The designs need not be constrained by the standard features as shown in this Code of Practice. However, it must satisfy the engineering requirements for performing the drainage functions without posing any maintenance or environmental problem. The specially developed waterbodies and watercourses shall be integrated into the development proposals and shall be maintained by the developers/owners of the developments. The approval of the Public Works Department shall also be sought for all such proposals.
12. Climate Proofing 12.1. Explanation of climate proofing Climate proofing in the context of this Code of Practice is a shorthand term for identifying climate risks associated with surface water drainage, and ensuring that those risks are reduced to acceptable levels through long-lasting and environmentally sound, economically viable, and socially acceptable changes in the planning, design, construction, operation, and decommissioning of drainage systems. This is implicitly linked to SUDS. Climate proofing includes both the risks arising from current climate variability and extremes and from the future incremental changes in those risks as a result of longer-term changes in climate extremes and variability. This Code of Practice sets out requirements and recommendations which will avoid most of the risks and damage costs attributable to climate change and variability which could potentially affect surface water drainage by considering climate proofing at the design stage of the project. The principals concerns for climate proofing for surface water drainage are: •
long term variations and changes in rainfall; and
•
rising sea level.
Risk based assessment of climate change indicates that there could be increasing incidence of storms and high intensity rainfall e.g. a rainfall that now occurs on average once every ten years may in future occur once every five years. The nature and magnitude of the change cannot be established with certainty but published results of application of climate models allow ‘order of change’ predictions to be made. Sea level at Port Vila is rising; in 2010 the rate is measured at 6.3 mm/year, although a minor fraction of this may be caused by settlement at the measurement site. Simple extrapolation of this rise gives a fairly reliable prediction for the medium term future but climate modelling and observation suggests the rate may be increasing. Sea level rise has impact on the elevation chosen for sea outfalls, and the platform, crest and ground floor level for buildings.
12.2. Requirements of Code of Practice 12.2.1. Rainfall Rainfall intensity-duration-frequency (IDF) curves have been synthesised for 2060. These are at Appendix 4. The curves are derived from application of predicted changes in rainfall probability from generic climate models to the 2009 IDF curves at Appendix 2 which are statistically derived from historical rainfall data up to 2009. The recommended design proceed is to prepared designs using the 2009 IDF but then check that the designs can accommodate the increased rainfall intensities predicted for 2060.
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12.2.2. Sea level The platform, crest and ground floor levels required under clause 2 make allowance for rises in sea level up to 2060. The elevations specified will be kept under review and the Public Works Department may periodically revise these levels. In the meantime the required levels are consistent with the economic life of most commercial buildings and infrastructure.
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PART III COMPLETION OF DRAINAGE WORKS 13. Certificate of Statutory Completion (CSC) 13.1. Drainage works according to approved plan Drainage works shall be constructed in accordance with the approved drainage plans, the ENTER NAME OF LEGISLATION and this Code of Practice.
13.2. Supervision (a) The Qualified Person shall comply with the relevant sections of this Code of Practice. (b) The Qualified Person shall be fully responsible for the supervision and construction of drainage works based on the approved plan. (c) The Qualified Person shall notify the Public Works Department of any proposed deviation of works from the approved plan and obtain approval for the deviation by submitting drawings showing the amendments before proceeding with the works. (d) The Qualified Person shall, if necessary, notify/apply directly to all the relevant authorities such as LIST RELEVANT AUTHORITIES before carrying out drainage works and shall abide by the conditions stipulated by the relevant authorities.
13.3. Completion of works On completion of drainage works, the Qualified Person shall certify and submit to the Public Works Department a Certificate of Inspection for Drainage Works.
13.4. ‘As-Constructed’ drainage drawings On completion of drainage works, the Qualified Person shall submit the ‘As-constructed’ drawings to the Public Works Department for record. ‘As-Constructed’ drawings for the following two categories of drainage works need to be submitted: (i) Drains and approved structures within Drainage Reserve; and (ii) Roadside drains (except for those built in accordance with the Ministry of Works standard designs). Submission requirements for ‘As-Constructed’ drainage drawings are shown in Appendix 5.
13.5. Survey plan A survey plan shall be submitted if a development or structure is constructed within less than 300 mm from a Drainage Reserve. The survey plan shall consist of a site plan and crosssections showing the development or structure and lot boundary in relation to the Drainage Reserve. The survey plan shall be prepared and endorsed by a Registered Surveyor.
13.6. Defects liability period Drainage works to be handed-over to the Public Works Department shall have a one year Defects Liability Period. The Defects Liability Period shall commence from the date the Public Works Department gives no objection to the issue of the CSC. The developer/owner shall pay for the cost of rectification of defects in the drainage works during the Defects Liability Period. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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13.7. Handing-over of drain Upon the expiry of the Defects Liability Period, the Qualified Person shall arrange for the handing-over of the drainage works to the Public Works Department after all the necessary or required rectification works are satisfactorily completed.
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Appendix 1: Rational Method The Rational Method provides a simple method for the design of urban drainage. However, because the methodology is simplistic the Rational Method must only be used within certain limits. For urban drainage the catchment area should not be more than 500 ha (5 km2). Alternatively it should not be used for pipe drains larger than about 600 mm diameter or the equivalent in non-circular shapes. In addition, and contrary to advice in some published guidelines, the simplistic assumptions mean that the method can grossly overestimate flow in sloping rural catchments typically more than 40 to 60 ha in area; or up to 1.0 km2 in area when the catchment is flat. The Rational Method does not provide a reliable basis for the determination of runoff volume, hydrograph shape, or peak discharge rates from historical (real) storms. It does not take into account either variations with time of the rate of rainfall and the area contributing to flow at the outfall, or the variations in the velocity of flow and in the temporary retention in the conduits. Therefore it must only be used to estimate of flow to design the size of drains and only within the stated limitations. The hilly character and coastal setting of Port Vila mean that drainage catchments are generally not larger than 5 km2 in area. Also, even if parts of the catchment are not yet developed the pace of development means they will probably be developed in the not distant future. It is therefore appropriate to use the Rational Method for urban drainage design within Port Vila. It also avoids more complicated calculations or the need for more specialist knowledge especially if this requires the application of computer models. Nevertheless it remains the responsibility of the designer to understand the limitations of the Rational Method and to know when an alternative methodology is required.
Principles and Assumptions In the Rational Method discharge at each point in a drainage system is calculated, starting with the most remote point from the outfall, and making the assumption that the whole area is contributing to the flow at the point under consideration at a time after the start of the rainfall equal to the time of concentration of the area. The time of concentration is the time water takes to flow to that point down the longest flow path from the most remote point including the time for water to flow across the surface and enter the drain, i.e. the inlet flow time, and the time of flow in the drain, i.e. the drain flow time. It is further assumed that the peak rate of runoff will occur at that time. The design storm is considered to have duration equal to the time of concentration, and the corresponding mean rate of rainfall is then multiplied by the contributing area to give the rate of runoff, producing the ‘rational’ formula.
Rational Formula In its general form the Rational Formula is:
Q p = 2.78CIA Where
Qp =
peak flow rate (m3/s)
C=
Runoff coefficient (dimensionless)
I=
Rainfall intensity, i.e. rate of rainfall (mm/h)
A=
Catchment area (km2)
2.78
is a conversion factor to suit the units used
The Calculation is then essentially one of trial and error, because the rate of rainfall is determined from the time of concentration which itself varies with the assumed size of drain PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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and some drain sizes need to be assumed in the first place before the calculation procedure can commence. Calculation of the flow at the various inlets and junctions along the drainage line is carried out from the top of the system progressively downstream. The total peak flow at any point is not the sum of the calculated sub-area flows contributing at that point, but is dependent on the time of concentration at that point. The actual flow being the product of the sum of the C x A values of the contributing sub-catchments, multiplied by I appropriate for time of concentration at that point.
⎡ ⎛ C A + C 2 A2 + ....... ⎞⎤ ⎟⎥ × I m3/s Q p = 2.78 × ⎢∑ ⎜ 1 1 ⎜ ⎟⎥ ∑A ⎠⎦ ⎣⎢ ⎝ By its nature the Rational Method is a very simple hydrological model that depends on its original development and calibration to estimate flows for catchments of typical shape and surface condition. This equation addresses variations in rainfall loss, surface storage, and the rate (speed) of surface runoff in a very simplistic manner. Within the Rational Method both the runoff coefficient and the time of concentration are adjusted to account for typical variations in catchment conditions as described below: (i) The runoff coefficient C takes account of variations in infiltration of rainwater into the ground across the catchment, and hence the selection of this coefficient is usually related to the fraction impervious. (ii) The runoff coefficient C also takes account of variations in rainfall losses relative to the total rainfall intensity and volume, and thus the coefficient is adjusted using the frequency factor Fy. (iii) The average rainfall intensity I takes into account variations in the average rainfall intensity over the period of the time of concentration. (iv) Indirectly, the average rainfall intensity I may also take account of typical variations in channel storage through variations in the methodology used to calculate the time of concentration; thus the method used to calculate tc varies with the type and size of catchment.
Rainfall intensity The rainfall intensity is obtained from the rainfall intensity-duration-frequency (IDF) curves, in this case the curves for Port Vila or Bauerfield according to the location of the catchment.
Catchment area The boundaries of catchment areas may be determined from contour maps, records, aerial photographs and field inspection. When determining boundaries the following factors should be considered: (i) Where the contributing catchment includes existing subdivided areas, the location of existing drainage works needs to be determined, either by field inspection, records, or from ‘As Constructed’ drainage plans. (ii) In urbanised catchments, ridgelines should not automatically be adopted as catchment boundaries because drainage systems may collect and carry storm water across the natural catchment boundary. (iii) The catchment area should take into account likely future road layouts and road drainage patterns if the contributing catchment includes areas subject to future development. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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(iv) In older urban areas where existing roads have a high crown, storm water runoff may be re-directed by the crown of the road. When determining the catchment area, appropriate consideration should be given to the likelihood that the road will one day be resurfaced and re-profiled, causing storm water to return to its natural flow path. In such cases, the design of new drainage works must adopt a conservative catchment area. (v) When assessing catchment boundaries, allowance should be made for the possibility of directing runoff against the natural ground slope, e.g. the connection of roof water drainage to the street. This may be especially significant in Industrial and Commercial areas where factory roofs and surrounding car parks may drain in opposite directions. (vi) Roads, fences and pathways may significantly alter catchment boundaries by either blocking or changing the direction of surface runoff. (vii) The effective catchment area of the minor drainage system may be different from the catchment area of the major drainage system. In some cases the piped drainage system may discharge at a different location to that of the overland flow path. (viii) In small urban catchments, the effective catchment boundary may be governed by the location of plot boundaries.
Coefficient of discharge The coefficient of discharge C in the Rational Formula is a statistical composite of infiltration and other losses, and to some degree, channel storage. It should not be confused with the volumetric runoff coefficient CV which is the ratio of total runoff to total rainfall. The coefficient of discharge must account for the probable future development of the catchment irrespective of whether there are current development proposals or the area has been included within planning or zoning maps. It shall never be less than the value determined for the catchment under existing conditions. It is recommended that the coefficient of discharge is calculated using the method presented in Australian Rainfall and Runoff6. This method is summarised in the following steps: STEP 1
Determine the actual fraction fi for the catchment making use the typical values from Table 8.
STEP 2
Determine the 1 hour rainfall intensity I10 for the 10 year ARI at the catchment read from the appropriate IDF.
STEP 3
1
Determine the Frequency Factor Fy for the required design storm from
Table 9. STEP 4
Determine the 10 year C value from Table 10 and Table 11.
STEP 5
Multiply the C10 value by the Frequency Factor Fy to determine the coefficient of runoff for the design storm Cy.
C y = F y × C10 Note, in certain cases the resulting value of Cy will be greater than 1.0, in such cases Cy = 1.0 shall be used. There is little evidence to support an allowance for either slope or soil type in fully developed urban areas. If there are significant local effects, and reliable data is available, then 6
Australian Rainfall & Runoff, Book 8 (1998). PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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adjustments for soil type may be incorporated within the calculations at the discretion of the designer. The recommended method assumes that catchments are essentially homogeneous, or where the pervious and impervious portions are so intermixed that an average is appropriate. In cases where separable portions of a catchment are significantly different, they should be divided into sub-catchments and different values of C applied. Table 8 - Fraction impervious vs. development category
Fraction Impervious fi
Development Category Central Business
1.00
Commercial, local Business, neighbouring facilities, service industry, general industry, home industry
0.90
Significant paved areas e.g. roads and car parks
0.90
Urban residential – high density, high-rise
0.90
Urban residential – high density, multi-unit dwellings > 20 dwellings/ha
0.85
Urban residential – high density, townhouse type development
0.70
Urban residential – low density (including roads)
0.45 to 0.85
Urban residential – low density (excluding roads)
0.40 to 0.75
Rural residential
0.10 to 0.20
Open space & parks etc.
0.00
Table 9 - Table of frequency factors
A.R.I. (years)
Frequency Factor Fy
1
0.80
2
0.85
5
0.95
10
1.00
20
1.05
50
1.15
100
1.20
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Table 10 - Table of C10 Values
Intensity (mm/hr) 1
Fraction Impervious fi 0.40
0.60
0.80
0.90
1.00
39-44
0.44
0.55
0.67
0.78
0.84
0.90
45-49
0.49
0.60
0.70
0.80
0.85
0.90
0.55
0.64
0.72
0.81
0.86
0.90
0.60
0.68
0.75
0.83
0.86
0.90
0.65
0.72
0.78
0.84
0.87
0.90
0.71
0.76
0.80
0.85
0.88
0.90
0.74
0.78
0.82
0.86
0.88
0.90
90-119
0.75
0.79
0.83
0.87
0.88
0.90
120-139
0.76
0.80
0.84
0.87
0.88
0.90
50-54 55-59 60-64 65-69 70-90
0.00
Refer to Table 11
0.20
I10
Table 11 - C10 values for Zero Fraction Impervious*
Dense scrub
Medium density scrub, or Good grass cover, or High density pasture, or Zero tillage cropping
Light cover scrub, or Poor grass cover, or Low density pasture, or Low cover bare fallows
Soil permeability
Soil permeability
Soil permeability
Land description Intensity (mm/hr) 1
I10
High
Med
Low
High
Med
Low
High
Med
Low
39-44
0.08
0.24
0.32
0.16
0.32
0.40
0.24
0.40
0.48
45-49
0.10
0.29
0.39
0.20
0.39
0.49
0.29
0.49
0.59
50-54
0.12
0.35
0.46
0.23
0.46
0.58
0.35
0.58
0.69
55-59
0.13
0.40
0.53
0.27
0.53
0.66
0.40
0.66
0.70
60-64
0.15
0.44
0.59
0.30
0.59
0.70
0.44
0.70
0.70
65-69
0.17
0.50
0.66
0.33
0.66
0.70
0.50
0.70
0.70
70-90
0.18
0.53
0.70
0.35
0.70
0.70
0.53
0.70
0.70
90-119
0.19
0.55
0.70
0.36
0.70
0.70
0.55
0.70
0.70
120-139
0.20
0.56
0.70
0.36
0.70
0.70
0.56
0.70
0.70
Note: * Coefficients are not suitable for soils compacted by construction activities.
Time of concentration General The Rational Method assumes that peak runoff Qp occurs when all parts of the catchment receiving steady, uniform rainfall intensity are contributing to the outflow at this point. This condition is met when the duration of rainfall equals the time of concentration tc. The time of concentration tc consists of the flow time to the drain inlet ti plus the drain flow time from the
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most remote drainage inlet to the point of design td, hence the time of concentration is calculated by the addition of these two components.
tc = ti + t d The significance is in the assumption that for a given design storm frequency; peak flow at the catchment outlet will result from a storm of duration equal to the time of concentration. In reality this is not always the case and it is the task of the designer to be aware of the correct application of the time of concentration. The inlet time ti varies depending on the overland travel distance, land topography and characteristics. The drain flow time td shall be estimated from the hydraulic properties of the drain The calculation of the time of concentration tc should be based on a fully developed catchment in accordance with current development proposals or the area included within planning or zoning maps
Minimum time of concentration Although travel time from individual elements of a system may in reality be as short as two minutes, the total nominal flow travel time to be adopted from any catchment to its point of entry into the drainage network should not be less than 5 minutes7.
Standard inlet time The use of the standard inlet times in Table 12 is recommended because of the uncertainty related to the calculation of time of overland flow. Inlet time is defined as the travel time from the top of the catchment to the first inlet or gully where flow enters the drainage conduit. The standard inlet time includes the travel time along a typical length of kerb or channel from near the top of the catchment to the first pipe or channel inlet. If the actual length of kerb/channel travel is unusually long, then an additional travel time must be added to the standard inlet time8. The inlet times in Table 12 are appropriate for traditional (i.e. non SUDS) low density residential areas where the top of the catchment is developed, but not if it remains undeveloped woodland, scrub or grass land. The average slopes referred to are the slopes along the predominant flow path for the catchment in its developed state. Notwithstanding the above, it is recommended that a maximum inlet time of 20 minutes be adopted for urban and residential catchments, including playing fields and park areas.
7
Rainfall intensity-duration-frequency curves do not include durations less than 5 minutes, this is the accepted practice because rainfall intensities less than 5 minutes duration cannot be determined reliably. 8 Chapter 4 of the Queensland Urban Drainage Manual – Volume 1, Second Edition 2007 provides explanation and several methods for calculation of additional travel time. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Table 12 - Recommended standard inlet times
Inlet Time (minutes)
Location Road surfaces and paved areas
5
Urban residential areas where average slope of land at top of catchment is greater than 15%.
5
Urban residential areas where average slope of land at top of catchment is greater than 10% and up to 15%.
8
Urban residential areas where average slope of land at top of catchment is greater than 6%and up to 10%.
10
Urban residential areas where average slope of land at top of catchment is greater than 3% and up to 6%.
13
Urban residential areas where average slope of land at top of catchment is up to 3%.
15
Drain flow times Drains are designed for steady uniform flow conditions and a one-dimensional method of analysis is used. Drain travel times are calculated by dividing the pipe length by the velocity.
td = Where
td =
drain flow time (sec)
L=
length of pipe (m)
v=
velocity (m/s)
L v
Pipe flow times Velocity can be determined by direct calculation, or from table or charts. This guidance recommends one of three methods: (i) charts based on the Colebrook-White equation; (ii) direct calculation from the Colebrook-White equation; or (iii) direct calculation from Manning’s equation (giving slightly less accuracy). A Pipe design chart is included at Figure 5. The Colebrook-White and Manning equations are tedious to calculate by hand but can be incorporated into the design spreadsheets for quick and reliable calculation. The Colebrook-White equation is:
v = −2(2 gDs )
1/ 2
Where
v=
velocity (m/s)
D=
Pipe diameter (m)
⎡ k ⎤ 2.5υ + log10 ⎢ 1/ 2 ⎥ ⎣ 3.7 D D(2 gDs ) ⎦
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s=
energy gradient (m/m)
υ=
kinematic viscosity (1.31 x 10-6 m2/s)
k=
equivalent sand roughness (mm)
g=
gravitational acceleration (m/s2)
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Manning’s equation is:
v= Where
1 2 / 3 1/ 2 R s n
v=
velocity (m/s)
R=
hydraulic radius (m) = A / P
where
A = Cross-section area of flow (m2) P = Wetted perimeter (m) s=
hydraulic gradient (m/m)
n=
Manning’s n
Manning’s n is related to the equivalent sand roughness, k, by the equation:
n=
k 1/ 6 83.3
(k in mm)
Velocity correction for pipe flow It is the convention to assume that pipes flow full bore which simplifies the calculation, the rationale being that even if in reality some pipes run only partially full for the design case this makes no difference because the objective is to design an adequately sized system, not model the behaviour of the system under one specific condition9. However, special circumstances apply in Port Vila because flow into drains is relatively small due to the high permeability of the underlying Coral Limestone; also the catchments are generally small. This means that under the design condition many pipe drains will not flow full bore, and when less than 50% full the velocity is proportionally less than the full bore velocity. It is therefore necessary to correct the velocity for compliance with the minimum self cleansing velocity, 1.5 m/s, section 6.2.2. This is achieved by reading the relatively velocity for the proportional discharge from Figure 6. This correction can be incorporated into spread sheet calculations.
Channel flow times Channel flow is calculated in the same way but in a channel there is always a free water surface open to the atmosphere so the calculation must be made with Manning’s equation.
9
Note that this is different from the design of foul sewers where the objective is to achieve self cleansing velocity under normal operating conditions and therefore with the pipe flowing partially full. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Hydraulic fiction (roughness) There has been extensive research on the comparative roughness of pipes of different materials. The findings10 suggest that regardless of material an equivalent sand roughness k of 0.6 mm should be used for pipe surface water sewers. Not overriding this recommendation, comparative values for k for different pipe materials are given in Table 13. Note the very high roughness values that occur when a sewer silts up. The higher suspended solid loadings of tropical sewers compared with those in temperate latitudes require much higher velocities to ensure non-silting conditions. If the likely loadings are known, self-cleansing velocities can be calculated, but the calculations are not easy and it is generally adequate to avoid velocities less than 1.5 m/s. If this is not possible regular flushing or jetting should be undertaken. Table 13 – Recommended equivalent sand roughness values k and Manning’s n
Sewer material
Equivalent sand roughness k (mm)
Manning’s n
Cast concrete
0.6
0.0110
Spun concrete
0.6
0.0110
Clay
0.3
0.0098
uPVC
0.15
0.0088
well pointed
3.0
0.0144
old with mortar loss
15.0
0.0189
Bricks or blocks:
Note: Where sediment is present in the pipe invert, very high resistance to flow can occur, equivalent to k values of up to several hundred millimetres.
10
Sewers for Adoption 6th Edition - a design and construction guide for developers, UK Water Research Centre, 2006. PTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Figure 5 – Hydraulic flow chart for k = 0.6 mm (Storm water sewers)
Notes: Hydraulic Flow based on Colebrook-White Pipes flowing FULL. Roughness Factor, k = 0.6 mm. Water Temperature 15ºC
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Figure 6 - Relative Velocity and Discharge in a Circular Pipe for any Depth of Flow
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Appendix 2: Rainfall Intensity-Duration-Frequency Curves Year 2009 The Port Vila IDFs shall be used for catchments in the Central Business District, No2 and all divisions to the south.
PORT VILA Duration Decimal hour 5 min 0.08 10 min 0.17 15 min 0.25 30 min 0.5 1h 1 2h 2 4h 4 8h 8 12 h 12 18 h 18 24 h 24
2 yr return period 92 84 78 64 48 34 23 15 11 8 7
Design Rainfall Intensities (mm/h) 5 yr return 10 yr return 25 yr return 50 yr return 100 yr return period period period period period 122 146 176 199 221 111 133 161 182 202 103 123 148 168 186 84 101 122 137 153 64 76 92 104 115 45 54 65 73 81 30 36 43 49 54 19 23 28 31 35 15 18 21 24 27 11 13 16 18 20 9 11 13 15 17
PORT VILA Synthesised Rainfall-Intensity-Duration Curves 2009
Rainfall Intensity in mm/h
1000
100
10
1 0.0
0.1
1.0
10.0
Duration in hours
2 yr return period 25 yr return period
5 yr return period 50 yr return period
10 yr return period 100 yr return period
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The Bauerfield IDFs shall be used for all diversions not otherwise permited for the Port Vila IDFs.
BAUERFIELD 2009 Duration Decimal hour 5 min 0.08 10 min 0.17 15 min 0.25 30 min 0.5 1h 1 2h 2 4h 4 8h 8 12 h 12 18 h 18 24 h 24
2 yr return period 99 92 86 73 57 40 27 17 13 10 8
Design Rainfall Intensities (mm/h) 5 yr return 10 yr return 25 yr return 50 yr return 100 yr return period period period period period 143 179 224 258 292 133 167 209 240 271 125 156 196 225 254 106 132 165 190 215 82 103 129 148 167 58 73 92 105 119 39 49 61 70 79 25 31 38 44 50 19 23 29 33 38 14 17 22 25 28 11 14 18 20 23
BAUERFIELD Synthesised Rainfall-Intensity-Duration Curves 2009
Rainfall Intensity in mm/h
1000
100
10
1 0.0
0.1
1.0
10.0
Duration in hours
2 yr return period 25 yr return period
5 yr return period 50 yr return period
10 yr return period 100 yr return period
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Appendix 3: Design Calculations for Road Gullies Step 1 - Determine longitudinal gradient:
Glong
drained width:
W
cross-fall:
Xfall
roughness coefficient, Manning’s n: use 0.013 Step 2A (Glong ≥ 0.5%)
Step 2B (Glong < 0.5%)
Read drained area, A from Figure 7.
Read gully spacing for roads of zero gradient, Lo from Figure 8. Read adjustment factor for different drained width, F from Figure 9. Read multiplication factor for different crossfalls and gradients, R from Figure 10.
Step 2A (Glong ≥ 0.5%)
Step 2B (Glong < 0.5%)
Determine unadjusted gully spacing, Lu
Determine unadjusted gully spacing, Lu
⎛ 0.01 ⎞ A Lu = ⎜ ⎟× ⎝ n ⎠ W
Lu = Lo × [1 + F (R − 1)]
Step 4 - Determine design gully spacing, L
L = Lu × (1 − RFgrating )× (1 − RFdebris )
Where:
reduction factor for gully efficiency, RFgrating from Table 5; reduction factor for blockage by debris RFdebris from Table 5.
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Figure 7 - Design chart for general calculation of drained area to gully
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Figure 8 - Design chart for gully spacing (Lo) for flat roads (gradient ≤ 0.5%)
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Figure 9 - Design chart for adjustment factor, F (Gradient < 0.5%)
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Figure 10 - Design chart for R factor for flat roads (Gradient < 0.5%)
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Appendix 4: Rainfall Intensity-Duration-Frequency Curves Year 2060 The Port Vila IDFs shall be used for catchments in the Central Business District, No2 and all divisions to the south.
RAINFALL-INTENSITY-DURATION 2060 PORT VILA Duration Decimal hour 5 min 0.08 10 min 0.17 15 min 0.25 30 min 0.5 1h 1 2h 2 4h 4 8h 8 12 h 12 18 h 18 24 h 24
2 yr return period 99 90 83 68 52 36 24 16 12 9 8
Design Rainfall Intensities (mm/h) 5 yr return 10 yr return 25 yr return 50 yr return 100 yr return period period period period period 131 155 195 224 258 119 142 178 204 235 110 131 164 188 217 90 107 134 154 178 68 81 102 117 134 48 57 71 82 94 32 38 48 55 63 21 24 31 35 41 16 19 24 27 31 12 14 18 21 24 10 12 15 17 20
PORT VILA Synthesised Rainfall-Intensity-Duration Curves 2060
Rainfall Intensity in mm/h
1000
100
10
1 0.0
0.1
1.0
10.0
Duration in hours
2 yr return period 25 yr return period
5 yr return period 50 yr return period
10 yr return period 100 yr return period
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The Bauerfield IDFs shall be used for all diversions not otherwise permited for the Port Vila IDFs.
RAINFALL-INTENSITY-DURATION BAUERFIELD 2060 Duration Decimal hour 5 min 0.08 10 min 0.17 15 min 0.25 30 min 0.5 1h 1 2h 2 4h 4 8h 8 12 h 12 18 h 18 24 h 24
2 yr return period 109 102 95 81 63 45 30 19 14 11 9
Design Rainfall Intensities (mm/h) 5 yr return 10 yr return 25 yr return 50 yr return 100 yr return period period period period period 150 188 236 269 300 140 175 220 250 279 131 164 206 234 262 111 139 174 198 221 86 108 136 154 172 61 77 97 110 123 41 51 64 73 81 26 32 41 46 51 19 24 31 35 39 15 18 23 26 29 12 15 19 21 24
BAUERFIELD Synthesised Rainfall-Intensity-Duration Curves 2060
Rainfall Intensity in mm/h
1000
100
10
1 0.0
0.1
1.0
10.0
Duration in hours
2 yr return period 25 yr return period
5 yr return period 50 yr return period
10 yr return period 100 yr return period
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Appendix 5: Submission Requirements for ‘AsConstructed’ Drainage Drawings Two sets of hard copy and one soft copy of the ‘As-Constructed’ drawings shall be submitted. The ‘As-Constructed’ drawings shall be endorsed by a Professional Engineer and, where applicable, also by a Registered Surveyor. The ‘As-Constructed’ drawings shall show the following details: (i) alignment and width of the Drainage Reserve. (ii) size and type of the constructed drain within the Drainage Reserve. (iii) longitudinal section showing the gradient, invert and cope level of the constructed drain. (iv) cross-section of the constructed drain in relation to the Drainage Reserve/lot boundary/retaining wall/boundary fence. (v) locations, sizes and types of all drain connections. (vi) piling records for drains and structures within the Drainage Reserve and roadside drains including entrance culverts. The piling records shall include the extent of piling, sizes, types, lengths and spacing of the piles. Reasons shall be stated if no piling is carried out. (vii) details of structures within Drainage Reserve such as bridge, crossing over drain, pedestrian crossing. (viii) structures (including piling records) beside Drainage Reserve, as and when required by the Public Works Department.
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Appendix 6: Sustainable Drainage Systems (SUDS) Urban environment Runoff from the impermeable surfaces of the urban or built environment can be highly polluting and can also increase the risk of flooding. The runoff may carry a mix of polluting substances, such as toxic metals, pesticides, oils and hydrocarbons, sediments and oxygen-depleting substances. The majority of surface water discharges receive no treatment before discharge to the receiving waterbody and this can lead to poor water quality and ecological damage. The concept of more sustainable management of this run-off can be promoted by installing 'softer' engineering systems, such as grassed swales and wetlands, as a means of controlling the rate of flow. These techniques, known collective as Sustainable Drainage Systems (SUDS), have much to offer to reduce pollution and flood risks.
Traditional drainage Traditional drainage is designed to move rainwater as rapidly as possible from the point at which it has fallen to a discharge point, either to surface or groundwater. This approach has a number of harmful effects: •
Run-off from hard paving and roof drainage can increase the risk of flooding downstream, as well as causing sudden rises in water levels and flow rates in drains and watercourses.
•
Surface water run-off can contain contaminants such as oil, organic matter and toxic metals. Although often at low levels, cumulatively they can result in poor water quality in the receiving waterbodies, affecting biodiversity, amenity value and potential water abstraction. After heavy rain, the first flush is often highly polluting.
•
By diverting rainfall to piped systems, water is stopped from soaking into the ground, depleting ground water and reducing flows in springs and watercourses in dry weather.
Where SUDS are used SUDS include tried-and-tested techniques which increasingly over the past two decades have been used on a range of projects, especially in more developed countries. Since the techniques are sustainable, environment friendly and cost-effective they are also very appropriate in less economically developed countries for: •
residential areas; and
•
commercial or industrial sites with large areas of roof and hard-standing.
They can also be successfully retro-fitted to existing developments.
Planning As with other key considerations in the planning process incorporating SUDS needs to be considered at the planning, as well as at the detailed design stage.
Techniques The SUDS approach to drainage incorporates a wide variety of techniques. As a result, there is no one correct drainage solution for a site. In most cases, a combination of techniques will be required. The techniques include
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Rainwater harvesting
Rainwater harvesting involves the collection and storage of rainwater on site and its use as a substitute for mains water. Rainwater harvesting in the form of collection of roof drainage is already widely practiced in Port Vila since the majority prefer it for drinking over chlorinated mains water; any surplus is not wasted as it used for other purposes around the household. •
Permeable pavements
The need can be reduced or eliminated where run-off is encouraged to permeate through a porous pavement, such as permeable concrete blocks, crushed stone or porous asphalt. Depending on the ground conditions, the water may infiltrate directly into the subsoil or be stored in an underground reservoir (for example, a crushed stone layer) before slowly soaking into the ground. If infiltration is not possible or appropriate (for example, because of ground contamination), an impermeable membrane can be used with an overflow to keep the pavement free from water in all conditions. Pollutant removal occurs either within the surfacing or sub-base material itself, or by the filtering action of the reservoir or subsoil. Most areas within Port Vila are favourable to use of permeable pavement because the underlying Limestone Coral is highly permeable and often near the surface. However there is little appreciation of the use of this technique and concrete is favoured for yards, sidewalks and the like. There is scope to promote the technique because done effectively it can eliminate the requirement for and cost of other drainage. •
Infiltration trenches and filter drains
An infiltration trench is a shallow, excavated trench that has been filled with stone to create an underground reservoir. Storm water entering the trench is gradually infiltrated into the ground. Their longevity can be enhanced by providing pre-treatment of the storm water using a filter strip, gully or sump pit to remove excessive solids. Filter drains are widely used by highway authorities for draining roads. They are similar structures to infiltration trenches but with the addition of a perforated pipe in the bottom of the trench. This facilitates the storage, filtering and some infiltration of water passing from the source to the discharge point. Pollutants are removed by absorption, filtering and microbial decomposition in the surrounding soil. Systems can be designed to successfully incorporate both infiltration and filter systems. Again the underlying geology of Port Vila favours their use. •
Swales and basins
These can be created as features within the landscaped areas of the site. Swales and basins are often installed as part of a drainage network connecting to a pond or wetland, prior to discharge to a natural watercourse. Swales are grassed depressions which lead surface water overland from the drained surface to a storage or discharge system, typically using the green space of a roadside margin. They may be used to replace conventional roadside kerbs and gullies, saving construction and maintenance costs. Compared to a conventional ditch, a swale is shallow and relatively wide, providing temporary storage, conveyance, treatment and encouraging infiltration to groundwater. A basin is designed to hold back storm runoff for a few hours and to allow the settlement of solids. They are dry outside of storm periods. They provide temporary storage for storm water, reduce peak flows to receiving waters, facilitate the filtration of pollutants (deposited and incorporated into the substrate) and encourage microbial decomposition, as well as allowing water infiltration directly into the ground.
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Ponds and wetlands
Ponds or wetlands can be designed to accommodate considerable variations in water levels during storms, thereby enhancing flood-storage capacity. Although these can be designed as wet or dry ponds, or wetlands, they are most likely to contribute to visual amenity and biodiversity where they include a permanent water body. By allowing adequate detention time, the level of solids removal can be significant. The algae and plants of wetlands provide a particularly good level of filtering and nutrient removal. Ponds and wetlands can be fed by: •
swales
•
filter drains
•
piped systems.
The use of inlet and outlet sumps enhances performance by trapping silt and preventing clogging of the outlet. Periodic removal of collected sediment from the inlet sump will be needed. Ponds are not a natural feature within Port Vila because of the high permeability of underlying rock. This does not preclude construction of artificial wet ponds making use of impermeable liner (e.g. Butyl) if this is deemed desirable to improve the quality of runoff before discharge to the receiving water body.
Diffuse water pollution Diffuse water pollution can arise from many sources, which may be small individually, but their collective impact can be damaging. Diffuse water pollution is mainly related to the management of land and soil. It can affect watercourses, coastal waters and groundwater. Diffuse pollution can be caused by current and past land use. Groundwater is vulnerable from, and can be affected by, pollutants that leach from the land surface and from areas of contaminated land. Surface waters are affected by rainfall that washes over and off the land (runoff). Watercourses can also be influenced by springs and seepages from groundwater that contribute to their flow. If the groundwater connection with surface waters is high, pollution can pass from one to affect the other. Run-off increases as more roads and houses are built. This often happens where development has degraded the natural permeability of the landscape and reduced its capacity to retain water. Unlike point source pollution, diffuse pollution cannot be controlled by issuing licences or permits. Regulatory approaches have to be more subtle and in many cases need to be well connected to the land use planning system.
Pollution prevention Prevention plays an essential part in the control of pollution, both by the prevention of run-off and the direct prevention of pollution. The prevention of pollution includes a wide range of measures designed to tackle urban diffuse pollution. These include: •
provision of oil separators;
•
safe oil and chemical storage at industrial sites;
•
safe disposal of waste oil and chemicals from domestic and industrial premises;
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•
minimal use of herbicides or the use of alternative techniques for weed control in public areas;
•
proper disposal of wash water from cleaning activities to the foul sewer;
•
steps to prevent the illegal connection of foul sewage flows to surface water sewers; and
•
a dog litter policy
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Appendix 2
DRAFT NATIONAL SANITATION POLICY FOR VANUATU
I.
Introduction
It is Government policy to raise the welfare of the people of Vanuatu. This policy is enshrined in the 1980 Constitution provision that guarantees the right and freedoms of the individual without discrimination on the grounds of race, place of origin, religious or traditional beliefs, political opinions, language or sex but subject to respect for the rights and freedoms of others and to the legitimate public interest in defence, safety, public order, welfare and health. Public welfare and health includes sanitation. The Vanuatu Infrastructure Master Plan 2002 laid down the Government policy on sanitation “to ensure the safe disposal and treatment of sewage, so that public health is safeguarded and so that is has minimum effect on amenity or the environment”. Measures to carry out septage disposal and control nutrient discharges within urban areas were adopted. In June 2006, the Priorities and Action Agenda (PAA) 2006-2015 of the Government documents the National Vision for Vanuatu as follows :
National Vision “An Educated, Healthy and Wealthy Vanuatu”
By 2015 Vanuatu will have achieved significant increase in real per capita incomes, along with steady growth in levels of employment. With the region, Vanuatu will be among the leading countries in achieving the Millennium Development goals in education, health, environmental management and other key social indicators. Public sector reforms will have raised standards of governance, levels of productivity in the civil service, and will have resulted in higher standards of services and managerial accountability. Through continuing structural reform, Vanuatu will have established an effective enabling environment to sustain the significant private sector growth, which it aims to achieve in output and employment. The PAA however, did not deal with sanitation as a separate strategic priority or sector strategy. There is need for Government to treat sanitation as an important and urgent issue that should be given utmost priority.
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II.
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Sanitation defined
Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic wastewater (sewage, sullage, greywater), industrial wastes, and agricultural wastes. Hygienic means of prevention can be by using engineering solutions (e.g. sewerage and wastewater treatment), simple technologies (e.g. latrines, septic tanks), or even by personal hygiene practices (e.g. simple handwashing with soap). Sanitation goes beyond the disposal of waste and the practice of protecting health through hygienic measures. It also covers environmental sanitation—the collection, treatment, disposal, and recycling of household, commercial, and industrial wastewater. Sanitation also encompasses changing attitudes and behavior, specifically hygiene habits, developing solutions (including financing), and creating a demand for sanitation as a means for making sanitation systems effective.
III.
The Situation
The current realities and conditions prevailing in Vanuatu that impact on the quality of lives of its people on the aspect of sanitation and all its ramifications, shape the basis for the development of this National Sanitation Policy. Thus:
•
Vanuatu has no piped system being used to collect and dispose of the domestic sewage. The population is relying on on-site disposal of the wastewater flow either through septic tanks and soak pits in the formal housing estates or as pit latrines and natural drains where informal type of housing is developed. The so-called black type sewage (toilet waste) is either diverted to septic tanks or to pit latrines while the grey type sewage, or what is commonly known as sullage, is sent to septic tanks or drains or to open areas where it infiltrates into the ground.
•
Septic tank users are mainly located in residential areas and living in high or medium type housing standards. They are all connected to the water distribution system. Individual pit latrines or water seal toilet users are living mainly in rural areas, without connection to the water distribution system.
•
In informal type of housing mainly located in Seaside, Manples and Blacksands areas to the north of Port Vila Urban area and in some villages, the population is using common type of toilets.
•
Only half of the population is using toilets. The other half relies on the bush to relieve themselves.
•
For large water users, either domestic or industrial, the wastewater flow is supposed to be diverted to independent wastewater treatment facilities built and equipped by the
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users on their property. Most of these treatment facilities are not well operating as analysis of results of the discharged “treated effluent” into the receiving body, show. •
The water quality of the receiving body indicates a growing pollution which is mainly affecting watercourses, the ocean water in the Bay area, as well as in the two shallow lagoons to the east side of Port Vila.
•
There is a noticeable reduction in the water quality in Port Vila harbor and Erakor lagoons in comparison to what can be expected in the open ocean water.
•
Climate change has increased the likelihood that heavy rainfall events will become more frequent. Building lots and roads at low points have become more and more water-logged even after an average intensity rain.
•
Serious drainage problems exist due mainly to inadequate storm water drainage facilities. Clogged underground drains and gully inlets, in combination with large areas of impermeable ground, keep rainfall runoff on the ground surface, resulting in localized inundations during heavy rainfall events.
•
Soil erosion along the seashore is exacerbated by tidal effects. Soil erosion in these areas is always progressing and affects among other things existing storm water drainage outlets’ stability.
•
Storm water runoff flowing along paved areas and open lands causes soil erosion and weakens the pavement structure.
•
While flooding is threatening personal safety and damaging properties, periodic inundation also has a direct incidence on public health, mainly as a breeding place for mosquitoes, and other disease vectors.
•
Rapid urban development in Port Vila town is causing increasing demand for larger quantities of water for different uses. At the same time, this development is having a direct impact on surface water pollution. This is affecting water quality in watercourses and seawater within the town and peri-urban areas, and is also resulting in increases in the incidence of water borne diseases and the decline of water and air quality in general.
•
Vanuatu is extremely vulnerable to natural disasters due to it its geographical location in the “ring of fire” and the “cyclone belt” of the Pacific. It is at risk from a wide range of climate-related hazards including coastal erosion, tropical cyclones, floods, landslides, and drought, which are expected to increase in severity and frequency as a result of climate change, warranting emphasis on climate proofing of infrastructure, policy and institutional capacity building for disaster risk management, and improving climate resiliency. An increasing frequency and severity of flooding has been reported in Port Vila caused by tropical cyclones and storm surges. Expected rise in sea level will exacerbate the impact of these events. Flooding and inundation of urban and periurban areas have negative economic impacts as national investments in infrastructure are located in low-lying coastal areas around the perimeter of the island.
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•
There is no government focal coordinating agency/unit for sanitation and waste issues in Vanuatu. Responsibility is scattered and fragmented between a number of different government department/agencies.
•
There is lack of training and support given to local authorities and personnel dealing with waste. Access to proper facilities and equipment to facilitate proper storage, collection, transportation, and disposal/treatment at both Municipality and Local Government levels is inadequate if not lacking.
IV.
The existing Legal Framework and Institutional Arrangements
The legal framework of Sanitation and Waste Management is as follows::
a. 1980 Constitution of the Republic of Vanuatu b. Public Health Act No. 22 of 1994 c. Environment Management and Conservation Act (2002) d. Water Resources Management Act of 2002 e. Water Supply Act of 1985 f.
Municipalities Act 5 of 1980
g. Decentralisation Act 1 of 1994
Despite existing policies and laws, sanitation services are unsatisfactory as they are not to the desired standard, causing problems related to health and hygiene, environmental degradation and economic losses. These problems are generally associated with the following: • • • • •
rapid urbanization through increased population movement to the capital; poor governance due to lack of implementation of existing legislation; lack of funding caused by budget constraints; choosing inappropriate technologies as well as the cost of providing them; lack of capacity of the various organizations needed to operate and maintain the services to be delivered due to shortages of qualified and experienced staff.
Ministry of Infrastructure and Public Utilities is responsible for utilities regulation, development of infrastructure and roads and other public works projects. Ministry of Finance is officially responsible to negotiate and repay loans from Donors and to find funding for ni-Vanuatu Government budget. Ministry of Internal Affairs is responsible for linking national government to local Government.
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Ministry of Health through the Department of Health (DOH) is given the responsibility of promoting public health which includes sanitation/ waste disposal. The major issues covered by the Act and under the responsibility of the DOH are diseases, pollution, health, building and housing requirements, vessels, water quality and others. Local government authorities have a number of responsibilities in providing sanitation services under existing legislation. •
Under Section 25 of the Municipalities Act, the Municipal Council is responsible for safeguarding public health in its area as well as to administer health services. Also under the same section if the Minister of Health is satisfied that the council is incapable of administering health services, by reason of insufficiency of staff or facilities, he may direct the council to appoint the Government as its agent to carry out such services at the council’s expense.
•
Section 32(3)(b) of the same Act also provides that the Municipal Council may construct sewers within the municipality. The Schedule to the Municipalities Act provides for municipalities to establish, acquire, erect, maintain, promote, assist and control sanitary services for the removal and disposal of night soil.
•
The Public Health Act gives legal powers to local government authorities (i.e. municipalities and local government bodies) in relation to sanitation services. Sections 49, 50 and 53 provide that every building within an urban and rural area shall be provided with a proper and adequate sanitation system that meets the local authority’s requirements.
•
The Decentralisation Act provides local government councils (e.g. SHEFA Provincial Council) with power to construct and maintain health centres. Local government councils also have power to set rules and regulations relating to public health and hygiene, however the provisions of the Public Health Act vest the local government councils the power to provide sanitation services outside of the municipal area(s).
V.
Existing Policies and Programmes on Sanitation
a. b. c. d.
VI.
Priorities and Action Agenda, 2006-2015 Sanitation Master Plan April 1998 Infrastructure Master Plan 2002 National Water Strategy 2008 - 2018
Policy Objective
All people of Vanuatu shall have access to adequate, affordable and sustainable sanitation system and facilities thereby improving their health and well being.
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Principles
The principles that form the framework of the sanitation policy are as follows :
a. Sanitation is a Priority. Access to and proper use of adequate basic sanitation facilities will improve human health and reduce infant mortality. The relationship between good sanitation and safe drinking water is clearly evident in the reduction of sanitation related preventable diseases as well as promoting health and livelihoods especially of women and children. Sanitation requires priority attention to enhance healthy living and overall development of the country.
b. Hygiene Practices Availability of sanitation facilities does not guarantee proper usage. Positive behavioral change through effective hygiene education and promotion is required.
c. Political Will Increased and sustained political will is required at all levels to generate commitment and interest in sanitation activities for improved coverage.
d. Environmental Impact of Sanitation Facilities, Including Climate Change A paramount consideration in the choice of any sanitation system is its long-term environmental impact, especially on the degradation of the quality of water resources. Identifying, predicting and evaluating the likely changes in health risk of individuals and community is therefore essential for effective planning and management of facilities.
In developing or improving sanitation facilities, the possible climate change effects also need to be kept in mind, from the following perspectives:
• •
•
climate change-related impacts could cause damage to infrastructure (e.g., increased infiltration of water into collection systems, flooding of facilities) climate change could result in either an improvement in, or diminution of, the efficiency of sanitation systems (e.g., increasing temperatures would increase the speed of bacteriological waste digestion; at the same time, increased temperatures could increase the spread of disease vectors) infrastructure development could cause increased greenhouse gas emissions (e.g., through increased fuel use for powering wastewater treatment facilities).
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e. Integrated Approach Sanitation development is essentially multi-sectoral. An integrated approach combining safe sanitation, hygiene education and promotion and safe water supply ensures improved health and livelihood. The successful promotion and implementation of a sanitation programme require that all stakeholders shall be involved from the pre-planning stage, through implementation to monitoring and evaluation stages.
f.
Gender Responsiveness
The disease burden on households, especially children, as a result of poor hygiene and lack of facilities has direct impact on women. The planning of, investment in, and promotion of sanitation facilities must therefore address the special needs, interest and priorities of women with due consideration for men and children to ensure adequate access, usage and maintenance.
g. Equity and Poverty Reduction The poor suffer most from lack of access to basic facilities and services. Access to sanitation for the poorest and most facility-deprived segments of the population shall be ensured as a means of improving socio-economic status.
h. Sustainable, Appropriate and Affordable Options Sanitation development is desirable. More desirable is the ability of the individuals and communities to afford, operate and maintain such facilities or systems and for these facilities or systems to be environment friendly. A variety of affordable and appropriate sanitation systems must be available to all users.
i.
Private Sector Participation
The activities of the private sector are usually run on a sustainable basis using sound business principles. Enabling environment shall be created for the promotion of different technology options and management for private sector participation in sanitation service delivery.
j.
NGO Participation
Non-governmental organizations have shown strong technical and community development skills that could be transferred and expanded for the benefit of the water and sanitation sector. Enabling environment shall be created for the effective organisational and institutional support to communities and government, by the civil society, particularly NGOs, to increase their participation in water and sanitation sector.
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k. Demand Responsiveness People will invest in providing sanitation facilities for themselves if they understand the benefits and can afford the cost. The choice of the type of sanitation facilities, preceded by health and hygiene education, must depend on the capability of the benefiting individual or community to pay for operation, maintenance and replacement. Through awareness creation and promotion of hygiene practices, communities shall be empowered to demand for improved sanitation. l.
Legislation
Appropriate legislation for the enhancement of sanitation delivery at all levels shall be enacted based on the existing Public Health Act, other sanitation related Acts, regulations and by-laws. Sanitation enforcement and other law enforcement agencies shall be empowered to deal with offenders of sanitation laws.
m. Ownership and Responsibilities The ownership of the facilities and the responsibility for operation and maintenance shall be that of the households and the communities.
n.
Building on Existing Practices
Holistic approach to sanitation development shall be adopted, building on existing safe practices, religious beliefs and socio-cultural norms of the people that are not in conflict with hygiene practices.
VIII.
Policy Strategies and Measures
In order to achieve the objective of the National Water Sanitation Policy, which is further elaborated by the Policy Principles, the following Policy strategies shall be adopted. a. Advocacy 1. Intensive and sustained social marketing shall be carried out as a means of stimulating the demand for the installation, use and maintenance of safe and appropriate sanitation facilities in households, communities and institutions in urban, peri-urban and rural areas of Vanuatu 2. All stakeholders shall prioritize sanitation activities through effective promotion in order to make up for the poor sanitation coverage in the country. 3. Increased and sustained political will is required at all levels through persistent advocacy and mobilization. 4. To ensure acceptability and funding of sanitation, strategies shall be developed to engage all leaders (political, traditional, religious, opinion, etc) in the prioritization of sanitation. 5. Access to sanitation for the poorest and most deprived segments of the population shall be ensured. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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b. Mobilization 1. Schools shall be used as focal points for promotion and empowering of children/youth to be agents of hygiene behaviour change. 2. Promotion of health education to ensure hygiene practices by users of public latrines/toilets in markets, parks, and recreation sites. 3. Sanitation programmes should take a gender sensitive approach by addressing the needs, preferences and behaviours of children, women and men. 4. Sanitation programmes shall take into consideration approaches that would improve the representation and voice of the poor and disadvantaged in policy discussions. 5. Sanitation programmes shall direct effort at setting up better communication and understanding for tackling the structural causes of poverty. Civil society organisations shall build networks and alliances that seek to promote awareness and enforcement of the basic rights. c. Capacity Building 1. Training (manpower development) for relevant personnel shall be conducted through workshops, seminars, etc. 2. Intensive health and hygiene education shall commence with a strategy for adequately reaching all parts of the country. 3. The Ministry of Education shall introduce or promote health and hygiene education as a compulsory subject in school curricula from the formative stage of life, from nursery schools, through primary and secondary schools to tertiary institutions especially teacher training institutions. Other informal school instructors shall be trained in basic health and hygiene education. 4. Health and hygiene education shall be an integral part of all community water supply and sanitation projects. The education shall address such basic subjects as personal hygiene, hand washing at critical times, safe disposal of excreta, household water security, cleanliness of kitchen and food hygiene, domestic solid and liquid waste disposal and, community storm-water discharge. 5. The Ministries of (a) Health Services, (b) Education, (c) Infrastructure and Public Utilities, (d) Internal Affairs, (e) Lands, Geology, Mines, Water Resources, Energy and Environment, (f) Justice, Social Welfare and Women Affairs and (g) Youth Development, shall make provision for health and hygiene education in all projects that will have direct impact on the community. d. Community Ownership and Management 1. It shall be the responsibility of the Communities to decide on sanitation after appropriate sanitation awareness programmes have been carried out. 2. The participation of people at household and community levels in the planning, provision, ownership and management of sanitation facilities shall be promoted.
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Major stakeholders shall support initiatives that help the poor and the disadvantaged people at household and community levels to address their basic and immediate sanitation needs.
e. Service Delivery 1. National and Local Governments shall reinforce the functions of well-trained and motivated Environmental Health Officers at community level to inspect and apply necessary sanctions to sanitation defaulters on a regular basis. 2. Future sanitation interventions shall be directed at achieving equitable distribution, while balancing economic and social considerations. 3. Adequate and regular supply of water shall be ensured before introducing water borne systems like septic tanks and sewerage. 4. The Government shall provide an enabling environment for effective partnerships with private sector to enhance local capacity and business opportunities towards sustainable sanitation development. 5. Sanitation improvement shall be approached incrementally based on safe local beliefs and practices. Wholesale introduction of new systems shall be adopted where appropriate. 6. Implementing agencies shall ensure safe citing of sanitary facilities to prevent the contamination of water sources. 7. Due consideration shall be taken while choosing Sanitation Systems to avoid negative impacts on the environment, e.g. sanitary land fill sites, large scale construction of ventilated improved pit (VIP) latrines and discharge of sewage effluent. 8. Government at all levels shall regularly present a list of technology options to satisfy demands of communities and individuals, based on their capability to pay for operation, maintenance and replacement, as and when necessary. f.
Participatory Approach 1. ,Sanitation improvements cannot be effected in isolation, It is essential that substantial linkages with other programmes in related sectors be ensured. 2. Promotion of sanitation shall be based on demand responsiveness of communities and individuals facilitated by effective social marketing. 3. Promotion of sanitation facilities shall be based on affordability and willingness to pay for the sustenance of the appropriate option. 4. Private sector involvement in implementation of sanitation programmes shall be promoted in such areas as hygiene education and promotion, construction and maintenance of sanitation facilities, etc. 5. Cost sharing shall also apply to operation and maintenance of public facilities, capacity building, research and development as well as monitoring and evaluation.
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Roles and responsibilities of Stakeholders
The stakeholders that have roles to play in the promotion and improvement of sanitation are as follows: a. b. c. d. e. f.
National Government Municipal and Local Government Councils Community and Households Private Sector Participation Non-Government Organisations Development Partners
a. The National Government 1. Shall take the lead in developing policies on sanitation upon adequate consultation with all stakeholders. 2. Shall facilitate the development of sanitation programmes for the urban and areas in consultation with all stakeholders. 3. Shall source funds from internal and external sources for the promotion of sanitation programmes. 4. Shall ensure separate appropriation and timely release of funds for sanitation activities annually. 5. Shall enact appropriate laws and regulations on sanitation. 6. Shall develop implementation strategies and guidelines for this policy. 7. Shall promote health and hygiene education as part of the curriculum at nursery, primary and secondary school levels, tertiary institutions particularly teacher training institutions, and informal institutions. 8. Shall provide technical assistance to Local Governments for the promotion of sanitation activities. 9. Shall be engaged in the monitoring and evaluation of sanitation improvement, to ensure compliance with accepted environmental practice, including due attention given to climate change considerations. 10. Shall ensure that all funds from internal and external sources for sanitation development are properly utilized. 11. Shall ensure the training and development of the requisite skills for all government personnel to be involved in sanitation at the national level including environmental health officers, monitors, enforcers and administrators. 12. Shall coordinate Development Partners’ activities in the sector. 13. Shall ensure the provision of appropriate and adequate sanitation facilities in all public institutions. 14. Shall adopt appropriate advocacy strategy to enlighten the populace on the need for good sanitation. b. Local Government 1. Shall ensure separate appropriation and timely release of funds for sanitation activities annually. 2. Shall make appropriate by-laws to support the planning, implementation and monitoring of hygiene and sanitation programmes. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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3. Shall source funds from internal and external sources for the promotion of sanitation programmes. 4. Shall develop hygiene and sanitation programmes for the local government headquarters and communities in their area in consultation with all stakeholders 5. Shall strengthen its Sanitation Unit or office. 6. Shall provide support to communities and households for sanitation development. 7. Shall ensure that all funds from internal and external sources for sanitation development are properly utilized. 8. Shall provide technical assistance to households for the upgrading of on- site sanitation facilities e.g. traditional pit latrines and evacuation of septic tanks. 9. Shall set sanitation fee or tariff where applicable, considering affordability and willingness to pay for services by the household. 10. Shall engage in the training and capacity building of government personnel (environmental health officers) and community artisans to be involved in water sanitation at the Local government and community levels. c. Communities 1. Communities shall participate at every stage of the decision making process of any sanitation programme. Such decisions shall include affordability and willingness to pay for the preferred sanitation option. 2. Social and cultural factors peculiar to each community shall be taken into consideration in arriving at a sanitation option preferred for the community. 3. Women shall be involved at all levels of decision-making and execution of sanitation programmes. 4. Promoters of sanitation shall persevere until the entire community accept the sanitation concept, as partial implementation of the accepted option will not yield the desired result. 5. If a public area is accepted for disposal of solid waste or public toilet, then all members of the community must observe and implement the community decision. 6. The community shall, with the aid of sanitation promoters, establish sanitation norms that must be accepted by all members. 7. The community shall sanction members that do not observe the accepted sanitation norms. Most communities have their own law enforcing methods and sanctions that can be applied. 8. The community while considering their norms shall establish structures and systems for self-monitoring and self-appraisal to ensure that agreed targets, and goals of hygiene and sanitation are achieved.
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d. Household/Individual 1. 2. 3. 4. 5. 6.
Each household/individual shall be available for health and hygiene education. Each household/individual shall take full responsibility for cleaning immediate environment and ensuring proper disposal of the wastes thereof. Each household shall be responsible for owning, appropriate use and maintenance of a sanitation facility for the disposal of human waste. Individuals must recognise the dangers of breeding disease vectors in their environment and shall ensure prevention of such situation. Children and women shall be part of the health and hygiene education programme. Every household/individual shall observe accepted sanitation norms and sanctions for defaulting.
e. The Private Sector Activities of the private sector are usually run on a sustainable basis using sound business principles. The attributes of the private sector shall be incorporated in the development of sanitation programmes. In specific terms, the private sector shall participate in the provision of the following services amongst others:
1.
Planning, design and contract supervision
2.
Large and small-scale construction.
3.
Operation and maintenance of all sanitation facilities.
4.
Supply of equipment and materials.
5.
Provision of finance
6.
Training and capacity building particularly skills development.
7.
Monitoring and evaluation of sanitation programmes.
e. Non-Government Organisations (NGOs) NGOs shall make use of their presence and acceptability in the community to supplement government efforts in promoting sanitation programmes especially health and hygiene education. In particular, the NGOs shall be involved but not limited to the following:
1. 2. 3. 4.
Advocacy and mobilization Health, hygiene education and sanitation promotion in the community. Development of community sanitation programme. Training and capacity building of the community.
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5. Developing communication materials that are easily understood and accepted by the community. 6. Sourcing and providing necessary finance for projects. 7. Bridging existing gaps between government and communities. 8. Shall work with lead government agencies to ensure generation and consolidation of relevant data.
f.
ADB, AusAID, other Development partners
Development partners provide financial and technical assistance with the Government of Vanuatu in the urban governance, drainage, sanitation and health sectors. Their assistance in the development and implementation of sanitation policies for Vanuatu shall include but not limited to the following:
1. 2. 3. 4. 5.
X.
Promotion of sanitation programmes through health and hygiene education. Operational research in sanitation issues. Funding and technical assistance Capacity building Monitoring and Evaluation of water sanitation projects and programmes.
Funding of Sanitation
a. Arrangement for funding sanitation projects shall be clearly and equitably spelt out. b. The Department of Health, Municipal Councils and Local Government Councils shall appropriate funds or allocate budget to implement sanitation programmes. c. A sanitation fee or tariff that will be affordable, fair, and sustainable while ensuring continuity and expansion of sanitation facilities shall be incorporated. Subsidies, where they exist, shall be transparent, effective and equitably applied. d. Funds may be sourced from Development Partners to promote implementation of hygiene and sanitation programmes. e. Capital investment for sewerage, storm water, on-site sanitation systems in public places and institutions shall involve cost sharing at all levels f. Government shall create an enabling environment for private sector, NGOs, households and communities to participate in hygiene and sanitation programmes.
XI.
Monitoring and Evaluation
a. The Government and communities shall make financial contributions to and be engaged in the monitoring and evaluation of hygiene and sanitation programmes within their areas of jurisdiction. b. All stakeholders shall regularly monitor the environmental impact of an adopted sanitation system. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Policy Review
a. The National and Local Government authorities shall review existing Acts, regulations and bye-laws which relate to sanitation. b. The Parliament shall enact laws that will promote sustainable sanitation activities. c. Local Government authorities shall formulate and pass bye-laws to regulate sanitation in their areas of jurisdiction.
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Appendix 3
REPUBLIC OF VANUATU Draft National Building Code Act No. __ of 201_ An Act to Adopt and Implement The National Building Code Be it enacted by the President and the Parliament as follows: 1.
Application of this Act
This Act applies to all design, location, siting, construction, alteration, repair, conversion, use, occupancy, maintenance, moving and demolition of, and addition to, public or private buildings and structures in Vanuatu. 2. Interpretations: In this Act, (a)
"architect" means a professional licensed to practice architecture in Vanuatu;
(b)
"building" means a building as defined from time to time by the Building Code;
(c)
"Building Code" means the regulations made pursuant to Section 3;
(d)
"building official" means a person appointed as a building official under Section 4;
(e)
"clerk" means the town clerk of a municipal council;
(f) "Committee" means the Building Advisory and Arbitration Committee established by this Act; (g) "construct" means to do anything in the erection, installation, extension, relocation, material alteration or material repair of a building and includes the installation of a factorymade building fabricated or moved from elsewhere; (h)
"council" means the council of a municipality or local government region;
(i) "demolition" means the doing of anything in the removal of a building or any material part thereof; (j)
"Minister" means the Minister responsible for the Building Code Act;
(k)
"municipality" means a town established under the Municipalities Act;
(l)
"National Building Code " means the National Building Code updated in ____;
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(m) "occupancy" or "class of occupancy" means the use or intended use of a building, as defined in the Building Code; (n) "owner" includes a person controlling the property under consideration either as an indigenous custom owner or a lessor or lessee under an approved leasehold agreement; (o)
"permit" means a permit issued pursuant to this Act;
(p) "professional engineer" means a professional licensed to practice engineering in Vanuatu; (q)
"regulations" includes municipal bye-laws.
3.
Adoption of the Building Code
3.1 The Minister may make such regulations as are considered necessary or advisable for the purpose of establishing a Building Code governing minimum standards for the construction and demolition of buildings and, without limiting the generality of the foregoing, may make regulations: (a) adopting by reference the Vanuatu National Building Code of 1990 or any change thereto or any other code or requirement issued by the ______________ or any change thereto, in whole or in part with such modifications and additions as may be specified in the regulations, and requiring compliance with it as adopted; (b) applying any or all the regulations to particular classes of buildings; (c) requiring the approval of a building official in respect of any method or matter of construction or demolition; (d) requiring notice to be given to a building official respecting (i) any matter in the course of demolition or construction, or (ii) any change in prescribed classes of occupancy made in a building; (e) requiring the transmission of reports and reviews to the building official; (f) requiring the making of tests, inspections or surveys necessary to prove compliance with the regulations; (g) requiring the remedying of an unsafe condition; (h) requiring that any part of the design, construction or demolition of a building be under the review of an architect, interior designer or engineer; i. respecting the qualifications required for a building official to inspect a class of buildings; ii. prescribing the board, organization or institution from which a building official must have obtained his or her training or certification;
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iii. respecting the requirement for accreditation of a training or certification program for a building official; iv. respecting the qualifications required for members of the Committee; v. respecting any other matter necessary or advisable to carry out effectively the intent and purpose of this Act. 3.2 Upon the recommendation of the Council, the Minister may, by regulation, prescribe additional standards applicable to the construction or demolition of buildings in that municipality or local government region, where such standards are more stringent than the standards in the Building Code or relate to matters not regulated by the Building Code. 3.3 At least forty-five days before prescribing regulations or amendments thereto under this Section, the Minister shall(a) give written notice of the Minister's intention to each council affected by the proposed regulations; and (b) give public notice of the Minister's intention by advertisement in a newspaper circulating in the municipalities and local government regions affected, which notice shall state (i) where the proposed regulations may be inspected, and (ii) the proposed effective date of the regulations. 3.4 Copies of any regulations made pursuant to this Section shall be mailed to the town clerk of every municipality or local government region. 4.
Administration and enforcement of the Act in municipality or local government region
4.1 The Council is responsible for the administration and enforcement of this Act in its municipality or local government region. 4.2 A building official or building officials shall be appointed by each council to administer and enforce this Act in the municipality or local government region. 4.3 The town clerk of the municipal council or the secretary of the local government council shall issue a certificate of appointment bearing that person's signature or a facsimile thereof to each building official appointed by the council who shall produce the certificate when requested to do so while in the performance of the building official's duties. 5.
Municipal Council or Local Government Regional Order
5.1 The Council may pass bye-laws/ regional orders not inconsistent with this Act or the regulations made by the Minister. (a) prescribing permits or classes of permits for the purpose of this Act and the regulations including permits in respect of construction or demolition or any stage thereof, and for occupancy and change of occupancy of a building;
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(b) providing for applications for permits and requiring the applications to be accompanied by such plans, specifications, documents and other information as is prescribed; (c) requiring the payment of fees on applications for and issuance of permits and prescribing the amounts thereof; (d) providing for the refunding of fees under such circumstances as are prescribed; (e) providing for the inspection of construction or demolition; (f) prescribing the time within which notices required by the regulations must be given to a building official; (g) prescribing an expiry date for construction or demolition permits. 5.2 A bye-law passed pursuant to this Section does not require the approval of the Minister but when a by-law is published, the clerk shall file a certified copy of the by-law with the Minister. 6.
Prohibitions
No person shall (a) construct or demolish a building to which this Act applies; or (b) occupy or change the class of occupancy of a building to which this Act applies, except in accordance with this Act or the regulations and unless a permit therefore has been issued by the building official and the permit is in force. 7.
Issue of permits
7.1
The building official shall issue a permit pursuant to Section 5 except where
(a) the proposed building or the proposed construction or demolition will not comply with an Act or a regulation or by-law made pursuant to this Act; or (b) the application therefore is incomplete or any fees due are unpaid. 7.2 An applicant for a permit shall inform the building official of any change in any information contained in the application. 7.3
The building official may revoke a permit
(a) where it was issued on mistaken or false information; (b) where, after twelve months after its issuance, the construction or demolition in respect of which it was issued has not been seriously commenced; or (c) where the construction or demolition of the building is substantially suspended or discontinued for more than twelve months.
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7.4 The building official shall not revoke a permit pursuant to subsection (3) until he has given written notice of his intention to do so to the permit holder and the owner of the building, if the owner is not the permit holder, at least thirty days prior to the proposed date of revocation. 7.5 Any decision to refuse a permit or to revoke a permit and the reasons there for shall be communicated in writing to the permit holder or the owner. 8.
Entry by building official
8.1 Subject to subsections 8.2 and 8.3, the building official may, for the purpose of ensuring compliance with the provisions of this Act or the Building Code, enter in or upon any land or premises at any reasonable time without a warrant. 8.2 The building official shall not enter any room or place actually being used as a dwelling without the consent of the occupier unless the entry is made during daylight hours and written notice of the time of the entry has been given to the occupier at least twenty-four hours in advance. 8.3 If a person refuses to allow the building official to exercise or attempts to interfere or interferes with the building official in the exercise of a power described in this Act, the municipal council or local government council on whose behalf the building official is acting may apply to the proper Courts for an order to allow the building official entry to the building and an order restraining a person from further interference. 9.
Powers of building official
9.1
For the purposes of an inspection pursuant to Section 8, the building official may
(a) require the production of the drawings and specifications of the building or any part thereof that are in the possession of the owner, the permit holder, if the permit holder is not the owner, or agent of the owner; (b) be accompanied by any person who has a special or expert knowledge of any matter in relation to a building or part thereof; (c) alone or in conjunction with such other person or persons possessing special or expert knowledge, make such examinations, tests, inquiries or, subject to subsections (2) and (3), take such samples or photographs as are necessary for the purposes of the inspection; (d) order any person responsible for the construction to take and supply at his own expense such tests and samples as are specified in the order. 9.2 Where a building official takes a sample pursuant to clause (c) of subsection 9.1, the building official shall divide the sample into two parts and deliver one part to the owner, the permit holder, if the permit holder is not the owner, or agent of the owner, as the case may be, if any of them so requests at the time the sample is taken, and the necessary facilities are provided. 9.3 Where a building official takes a sample pursuant to clause (c) of subsection 9.1 and has not divided the sample into two parts, a copy of any report on the sample shall be given to the owner or his agent, or the permit holder, if the permit holder is not the owner, as the case may be. PPTA Consultant’s Report Egis-Bceom International (France) in association Qualao Consulting Ltd. (Vanuatu)
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Order to comply
10.1 Where a building official finds that any provision of this Act or the Building Code is being contravene or where a building official has given notice of intention to revoke a permit, the building official may give to the person whom the building official believes to be the contravenor and the owner, if not the contravenor, an order in writing directing compliance with such provision and may require the order to be carried out forthwith or within such reasonable time as the building official specifies. 10.2 Where a building official gives an order pursuant to this Section, the order shall contain sufficient information to specify the nature of the contravention and its location. 10.3 Where a building official gives an order pursuant to this Section, the building official may affix a copy thereof to the site of the construction or demolition, and no person, except a building official, shall remove such copy unless authorized in writing by the building official. 10.4 Except where an order given pursuant to subsection 10.1 is an order that the construction or demolition cease, where an order of a building official made pursuant to this Section is not complied with within the time specified therein or, where no time is specified, within a reasonable time in the circumstances, the building official may order that all or any part of the construction or demolition cease and such order shall be served on the permit holder, the owner if the owner is not the permit holder and on such other persons affected thereby as the building official specifies. 10.5 An order made pursuant to subsection 10.4 shall be posted on the site of the construction or demolition and no person except the building official shall remove such copy unless authorized in writing by the building official. 10.6 Where an order to cease construction or demolition is made pursuant to subsection 10.4, no person shall perform any act in respect of the construction or demolition of the building in respect of which the order is made other than (a) such work as is necessary to carry out any other order of the building official made pursuant to this Section; or (b) such work as is necessary to make the site of the construction or demolition safe. 11.
Vanuatu Building Advisory and Arbitration Committee
11.1
There is hereby established a Vanuatu Building Advisory and Arbitration Committee.
11.2 The Minister may appoint to the Committee such number of members as the Minister determines for such terms as may be specified in the appointments. 11.3 The Minister may prescribe the remuneration to be paid to members of the Committee. 11.4 The Minister may designate from among the members of the Committee a Chair and a Vice-chair. 11.5
A majority of the members of the Committee constitutes a quorum.
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12.
Functions of Committee
12.1
The Committee shall
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(a) provide the Minister with such advice and assistance concerning this Act and the regulations as the Minister may from time to time require; (b) provide a liaison between the Minister and any persons or bodies interested in construction standards; (c) hear appeals as provided by Section 13; (d) respond to a matter referred to it by the courts pursuant to Section 14; (e) perform the duties and functions assigned to it by the Minister. 13.
Ruling on dispute
13.1 Where a dispute arises between an owner of a building or the owner's agent and building official respecting the technical requirements of the Building Code or the sufficiency of compliance with such requirements, or respecting an order made by the building official pursuant to Section 10, the owner or the owner's agent may make an application to the Committee for an arbitration or a ruling on the subject-matter of the dispute. 13.2 For the purposes of subsection 13.1, the agent of the owner includes any person employed by the owner in the design or construction of the building. 13.3 An applicant for an arbitration or a ruling shall cause notice of the application to be served on the building official. 13.4 The Committee may, with the approval of the Minister, establish the procedure to be followed before it in resolving a dispute, which may consist of the presentation of (a) written submissions; (b) oral submissions; or (c) a combination of written and oral submissions, and the examination of witnesses on oath or affirmation. 13.5 The parties to a dispute may agree upon the procedure to be followed by the Committee in the consideration of a particular question from among the procedures approved pursuant to subsection 13.4 but, in the absence of such agreement, the Committee shall decide which arbitration procedure will best permit the resolution of the dispute in the shortest practical time. 13.6 The Committee may seek advice from such experts in the matter under consideration as it may deem advisable, but no decision shall be made until the parties to the dispute have received any report received by the Committee pursuant to this subsection and have responded to it.
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13.7 A member of the Committee shall not participate in a decision of the Committee pursuant to this Section where there is a hearing unless that member is present throughout the hearing and hears the submissions of the parties. 13.8 No member of the Committee shall participate in the making of a decision pursuant to this Section where the member has an interest in or has previously considered the subjectmatter of the dispute. 13.9 The Chair may designate the members of the Committee who will consider an application for a ruling and, where the Chair is not one of the members so designated, the member who shall preside at any meeting of or hearing held by the members so designated. 13.10 The Chair may, pursuant to subsection 13.9, designate fewer members of the Committee than a quorum thereof. 13.11 Notwithstanding subsections 13.9 and 13.10, an application shall be considered by at least three members of the Committee. 13.12 A decision of the members designated pursuant to subsection 13.9 is a decision of the Committee. 13.13 A decision of the Committee pursuant to this Section shall be in writing although, where time constraints warrant, an oral decision may precede a written one. 13.14 A decision of the Committee pursuant to this Section shall either confirm the interpretation of the building official or shall be substituted for the interpretation of the building official and an order of the building official which is the subject-matter of the appeal shall remain in force until the Committee has rendered a decision.
14.
Appeal to Supreme Court
14.1 Any person who is adversely affected by an order given or decision made by the building official under this Act, or by a decision of the Committee may, within thirty days after the order or decision is made, apply to the Supreme Court for a hearing and appeal. 14.2 Where an application is made pursuant to this Section in respect of a matter in which a question is pending before the Committee, the proceeding before the Committee is terminated. 14.3 Where an application is made to the court for a hearing pursuant to subsection 14.1, the court shall appoint a time for and hold a hearing within thirty days after the application is made and may rescind or affirm the order or decision of the building official or the Committee, or take such action as the court considers the building official ought to take in accordance with this Act and the regulations, and for such purposes, the court may substitute its opinion for that of the building official or the Committee. 14.4 The court may refer a question respecting the technical requirements of the Building Code or the sufficiency of compliance with such technical requirements to the Committee for a determination, and the procedure before or the composition of the Committee shall be determined pursuant to Section 13, following which the Committee shall report to the court.
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14.5 The court to which application is made for a hearing pursuant to subsection 14.1 may extend the time for making an application either before or after the time fixed therein, where the court is satisfied that there are prima facie grounds for granting relief to the applicant pursuant to a hearing and that there are reasonable grounds for applying for the extension and may give such directions as the court considers proper consequent upon the extension. 14.6 Where, in the court's opinion, it is necessary in the interest of public safety and would not destroy the subject-matter of the appeal, the court may, upon application there for, order that the order or decision appealed from not be stayed pending the outcome of the appeal, but shall take effect immediately. 15.
Appeal to Court of Appeal
15.1 Any party to the hearing before the Supreme Court pursuant to Section 14 may appeal the decision to the Court of Appeal in accordance with the Civil Procedure Rules. 15.2 The Minister, either personally or by agent, is entitled to be heard upon the argument of an appeal pursuant to this Section. 15.3 An appeal pursuant to this Section may be made upon any question that is not a question of fact alone. 16.
Inquiry
16.1 Where it appears to the Minister that there is or may be a failure in construction or demolition standards or in the enforcement of this Act or the Building Code, the Minister may designate a person to conduct an inquiry into such failure. 16.2 For the purposes of an inquiry pursuant to subsection (1), the person conducting the inquiry has the powers, privileges and immunities of an Ombudsman, , officer or employees under the Ombudsman Act of 1998. 17.
Offences
17.1
Every person who
(a) knowingly furnishes false information in any application made pursuant to this Act or in any statement or return required to be furnished pursuant to this Act or the regulations; (b) fails to comply with any order, direction or other requirement made pursuant to this Act or the regulations; (c) contravenes any provision of this Act or the regulations, and every director or officer of a corporation who knowingly concurs in such furnishing, failure or contravention is guilty of an offence and on summary conviction is liable to (d) in the case of an individual, a fine of not less than _________ Vatu and not more than _______________ Vatu or to imprisonment for a term of not more than one year, or both; and (e) in the case of a corporation, a fine of not less than ___________ Vatu and not more than _______________ Vatu
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Notwithstanding subsection 17.1, where
(a) an individual knowingly commits; (b) a director or officer of a corporation knowingly directs or authorizes, assents to, acquiesces in or participates in the commission of; or (c) a corporation, whose director or officer knowingly directs, authorizes, assents to, acquiesces in or participates in the commission of, an offence referred to in subsection 17.1 that results in (d) the loss of human life, injury or damage to the health of a person; or (e) a catastrophic impact on the community, that person is guilty of an offence under this subsection and not under subsection 17.1, and is liable on summary conviction to (f) in the case of an individual, a fine of not more than _____________ Vatu or to imprisonment for a term of not more than two years, or both; and (g) in the case of a corporation, a fine of not more than ________________ Vatu. 17.3 Where an offence under subsection 17.1, 17.2 or 17.6 is committed on or continued for more than one day, it is deemed to be a separate offence for each day on which the offence is committed or continued. 17.4 Any fines resulting from an offence under this Act accrue to the municipality or local government region in which the offence took place. 17.5 In addition to any other penalty imposed for the conviction of an offence under this Act, the court may order the person to comply with this Act, the regulations, any by-laws made pursuant to this Act or a license, a permit or any direction issued under this Act. 17.6 Any person who fails to comply with an order issued under subsection (4) or (5) is guilty of an offence and is liable to the penalties set out in this Section.
18.
Limitation period
The limitation period for the prosecution of an offense under this Act is ______ years from the date of the commission of the alleged offense. 19.
Action for remedy
19.1 In addition to any other remedy provided for by this Act, the council of the municipality, or a standing committee thereof, may authorize an action or other legal proceeding to be brought in the Supreme Court for any or all of the remedies provided by this Section.
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19.2 The Court or a judge thereof may, where a contravention of or failure to comply with this Act, the regulations or an order made pursuant to this Act has been established, (a) make orders, restraining the continuance or repetition of such contravention or failure and the new or further contravention or failure in respect of the same building; (b) make orders directing the removal or destruction of the building or structure or a part thereof that is in contravention of or fails to comply with the Act or regulations, and authorizing the council, a standing committee or official thereof, if such order is not complied with, to enter upon the land and premises with such necessary workers and remove and destroy the building or structure or part thereof at the expense of the owner; and (c) make such further order as to the recovery of the expense of any such removal and destruction, and to enforce the Act and regulations, and as to costs, as the Court or judge deems proper, and any such order may be interlocutory, interim or final. 20.
Amendment of proceeding
In the event of a fresh offence by the same person against the Act or regulations after an action or other legal proceeding has been commenced, it shall not be necessary to bring any other action or proceeding, but the action or proceeding already begun and any pleading or information therein may be amended from time to time at any time before final judgment so as to include such fresh offences and the Court or judge shall hear, deal with and determine the whole matter of such violations. 21.
Evidence or proof
21.1 The production of a printed volume or paper purporting to contain the Building Code or the National Building Code of Vanuatu or any other code adopted by regulation, or any amendment, revision or abridgement thereof is prima facie evidence of the Building Code or the National Building Code, other code, amendment, revision or abridgement, as the case may be. 21.2 In any prosecution for an offence pursuant to this Act, a copy of a direction or order purporting to have been made under this Act or the regulations and purporting to have been signed by the person authorized by this Act to make the direction or order is prima facie proof of the direction or order without proof of the signature or authority of the person by whom it purports to be signed. 22.
Public utilities
Notwithstanding the provisions of the Municipalities Act 5 of 1980, the Decentralisation Act 1 of 1994, the Electrical Supply Act 21 of 2000 or any other Act and the Concession Agreements for supply of Electricity in Port Vila and Luganville, the Water Supply Act and the Concession Agreements, the Telecommunications Act of 1989, no public utility or concessionaire shall make a new permanent connection, or supply electric power, energy, water or steam heat through such connection, to any building until it is established that all permits required by this Act or the regulations prior to occupancy of the building have been obtained.
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23.
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Service of notice
Except where otherwise provided, any notice required by this Act to be served may be served personally or by registered mail addressed to the person to whom notice is to be given or his agent for service at the person's or agent's last known address. 24.
Interest of building official
24.1 No building official shall grant or revoke a permit, conduct an inspection or make an order pursuant to this Act in respect of a building or property in which the building official has any interest. 24.2 Where subsection 24.1 precludes a building official from acting and where no other building official is available, the building official shall notify the Council, which shall appoint a person to act as a building official for that purpose. 25.
Effect on other laws
25.1 This Act and the regulations supersede all Acts, Municipal or Local Government Council bye-laws governing the construction or demolition of buildings, except with respect to construction or demolition a) for which a permit has been issued before the first day of ___________ 20__, and that has been seriously commenced within twelve months of the date the permit was granted and is not afterward abandoned for a period of more than ninety days, or b) where no permit is required, which has been commenced before the first day of ___________ 20__ and is not afterward abandoned for a period of more than ninety days. 25.2 Nothing in this Act or the regulations affects the provisions of the Water Supply Act, Electric Supply Act, The Telecommunications Act, and the Utilities Regulatory Authority Act and the regulations made there under. 25.3 Where the provisions of any private or local Act conflict with the provisions of this Act, the provisions of this Act prevail. 26.
No action
No action or proceeding lies against the Government, a municipality or an official or agent thereof for any matter or thing done or omitted to be done by them in good faith and with reasonable care in exercising their powers or carrying out their duties under this Act or the regulations.
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Appendix 4 EA PROCUREMENT CAPACITY ASSESSMENT A. Introduction 1. ADB’s Project Administration Instructions (PAI 1.1 para. 10) require that project divisions and project processing missions assess the EA’s capacity to procure the goods, works and consulting services as part of the project preparation process. 2.
The purpose of the EA capacity assessment is to: (i)
Identify levels of reputational risk to ADB and its Borrowers and put in place appropriate prior review and process thresholds to mitigate this risk balanced with the needs for operational efficiency.
(ii)
Identify any implementation risks present in terms of procurement resources, structure and process and propose mitigating measures.
(iii)
Build on the existing knowledge base for procurement capacity, legislative environment and processes.
B. Contents of the Capacity Assessment 3.
The assessment contains three components. (i) (ii) (iii)
4.
The assessment of the general procurement environment A questionnaire to be completed by the EA The Procurement Capacity Assessment Report Recommendations
and
Templates for these are attached as appendix 1 through 3.
C. Undertaking the Assessment 5. The assessment of the general procurement environment will be undertaken by COSO in consultation with the RM and updated on an annual basis. COSO shall make this available to each project processing missions on request. In the event that one has not been prepared, COSO will prepare it in parallel with project processing completing it prior to circulation of the first draft of the RRP. 6. The questionnaire with guidance notes should be issued to the EA during project processing. The project officer may request that the PPTA consultants, if recruited, assist the EA in the completion of the questionnaire. The PPTA consultants will not assist ADB with the preparation of the Procurement Capacity Assessment Report, this is in part an assessment of ADB’s risks and therefore should not be outsourced. 7. Based upon the assessment of the general procurement environment and analysis of the EA’s completed questionnaire, project processing staff shall prepare a Procurement Capacity Report and Recommendations and attach it as a supplementary appendix to the draft RRP. This supplementary appendix should be
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provided to COSO as a matter of course with the first draft RRP inviting interdepartmental comments to COSO. COSO will assist and provide comments on the Report prior to circulation of the first draft RRP if so requested. 8. Refer to project administration instruction (PAI) 3.03 and 3.04 when setting the threshold for different modes of goods and works procurement. Consult with COSO when establishing the ICB procurement threshold for goods and works procurement. The criteria and thresholds for selecting different consulting recruitment methods are provided in the PAI, in particular PAI 2.02E, and should be used unless there are reasons for not doing so, in which case consult with COSO. D. Advance Contracting and Small Projects 9. When ADB approves advance contracting, no separate assessment need be undertaken provided that the prior review process is that described in Appendix 1 of both the Procurement Guidelines and Consultants Guidelines and do not exceed the process thresholds set in the PAI 3.04, paragraphs 3 through 6. 10. required
For projects valued under USD 10 million, no capacity assessment is
E. Outputs of the EA Procurement Capacity Report and Report and Recommendations 11. The EA Procurement Capacity Report and Recommendations shall set the project procurement thresholds that will be input into Section 1 A of the Procurement Plan and ADB Prior and Post review requirements that will be input into Section 1 B of the Procurement Plan. 12. The EA Procurement Capacity Assessment Report once commented upon by COSO shall be sent to the EA for review and confirmation at loan negotiations.
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EA Capacity Assessment Appendix 4A General Procurement Environment Assessment 1. Is there a procurement law? The answer to this is a simple yes or no, i.e. is their a single law governing procurement which is representative of best practice or is procurement governed through various laws, decrees etc.? Assess this as either “High” or “Low”
2. Are the laws and regulations clear and concise? If there is no single law check “high”, and similarly if the law is complex and difficult to follow check “average”. If the law is easy to follow check “low”. 3. What does the law (or regulations applicable to procurement) cover? If there is a single law, “low” will apply when the law covers drafting and use of standard bidding documents evaluation, contracting, through to the management of contracts including payment, warranty and defects liability periods. The less the procurement process is covered the higher the risk. If there is no single law, check “high”
4. Does the law cover the procurement of consulting services? If consulting services are not covered or there is no law the risk is high, if they are covered the risk is low. 5. Does the law differentiate between processes for consulting services and Goods/Works? If there is no law, or it applies the same processes to consulting services as for goods and works check high. If there is some differentiation but the processes are similar, check average. If consulting services are dealt with separately check low
6. Does the law require advertisement of all procurement opportunities Low risk will be represented through advertisement all above $25,000, average above all above $100,000, high by no advertisement or advertisement at a higher threshold than $100,000. 7. Are contract awards advertised? The same thresholds as stated at A6 should be applied 8. Are there restrictions on goods works and services on the basis of origin? If procurement is limited to solely national origin check high, if there are restrictions or a national preference
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Yes. The Public Finance and Economic Management Act 1998, Part V outlines authorities and amounts. The Government Contracts and Tenders Act 1998 and Regulations apply to all government purchases above VT5.0 million. Low. Yes. There is a single law. Low.
The law covers transparent processes of advertising and inviting the bids, evaluation processes and recommendation for award of contracts by Central Tenders Board and final award of contract by Council of Ministers. Low. Yes. Low. . No. The law does not differentiate between consulting services and goods/works and applies applies same processes to consulting services as goods and works. High Yes. Low-Average. Above $50,000 value are advertised and are termed as complex procurement. Yes. Average. Value above $100,000 No. Low.
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scheme, average. If None low 9. Does the law or relevant legislation and regulations provide acceptable provision for the participation of state owned enterprises? Only if the SOE is legally and financially autonomous and not a dependent agency of the purchaser low, other than this high 10. Are there restrictions on the nationality of bidders and consulting firms invited? If procurement is limited to solely national firms and individuals check high, if there are restrictions or a national preference scheme, average. If None low 11. Are foreign bidders and consultants forced to offer through or with local partners? If yes, high, in certain circumstances average, never, low 12. Is there a domestic preference scheme? If there is across the board high, if applicable in limited circumstances, average, if none, low. 13. Is there a national standard mandated for use for quality control purposes? No, or Yes with direct, accessible international equivalents low, yes without international equivalents high 14. Are any agencies exempt from the law? Such as the security forces, if yes high, also high of any types of goods are exempt from parts of the law such as medicines, text books or any other commodity 15. Is the default method for procurement open competition? Either yes or no and low or high 16. Is open procurement easily avoided? If the procurement law allows avoidance of open procurement above the national threshold on the basis of circumstances that are not in response to natural disasters ,i.e. simple urgency, check high, if open procurement can be avoided by senior management decision average. If avoidance requires approval of an oversight agency, low. 17. Do the rules and regulations require pre-qualification? Only for complex contracts, low, no contracts average, all contracts high. 18. Do the rules and regulations require registration? If yes, high, if only for specialist goods such as medicines average. If no registration low. 19. Are there systematic procurement process audits? Yes, low. Only financial audits average, none, high 20. Is there a national procurement manual or guide? A single procurement manual or guide, low, manual exists but out of date/not in wide use average, none high 21. Do the laws and regulations mandate the use of standard documents? Documents for goods, works and consultants services low, just for 2 of the three average, only one or none
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NO. Low. The Airports Authority is the only OSE but does not execute works. No. Low.
No. Low. Encouraged but not forced. No. Low. No. Low. ASSHT, Australian, NZ and U.K. standards. No. Low.
No. Low. No. Low.
Yes. Low. Estimated value above $1,000,000. Low. Average. Financial audits only. Yes. Low. There is a guideline for procurement of goods and services, June 2005 but requires review and update. No. State Law Office comments on documents. Changes are
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high 22. Have these standard bidding document’s been approved for use on ADB projects? Yes low, some but not all average, no high, 23. Do the regulations require the collection of nation wide statistics on procurement? Yes and statistics collected low, yes but data not collected or used average, no high 24. Is consolidated historical procurement data available to the public? Yes low, too much or too little, average, no high 25. Do the procurement laws and regulations contain provisions for dealing with misconduct? Such as fraud and corrupt practices – the procurement law or regulations may include or cross refer to anticorruption legislation. Yes low, no high. 26. Is fraud and corruption in procurement regarded as a criminal act? The penalties should include penal servitude (prison) yes low, no high. 27. Have there been prosecutions for fraud and corruption? If there have been successful prosecutions for fraud and corruption, low, if prosecutions seem to focus solely on low grade junior staff average, none high 28. Is there an alternative disputes resolution process independent of government and courts? If there is an arbitration law and independent process low, if the standard contracts use ICC or similar dispute resolution average, if arbitration is through the courts or can be overturned by courts high. 29. Does the law allow for sovereign immunity to the EA for claims against it? If plaintiffs can sue the government for contractual non-performance low, if they cannot high 30. Do the regulations allow for black listing (disbarment) of firms and individuals and if the do? If there is no black listing process or the process is transparent and equitable and undertaken by an independent oversight agency low. If there is a process and it is administered by a single line agency such as finance average, if it is administered by the executing agency high. 31. Which body oversees procurement? Independent body reporting to the elected body low, single body reporting to the cabinet average, no body or reports to a single state agency such as the Prime Minister or Finance Minister high.
32. What powers does the oversight body have? If the body can impose administrative sanctions on an EA and its staff and overturn contact awards including ministerial decisions low, if the body only can impose sanctions through the head of the EA, average, if the body can only recommend action high 33. Is there a nationwide procurement training plan?
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made according to needs. No. There has been no ADB projects for the past 10 years. No. High. Yes. Low. Available upto 10 years. Yes. Low.
Yes. Low. Yes. Low.
Yes. Low. The arbitration is done outside the country. No. Written in the contract but not in law. Average. Recommendations to Ministry of Finance and Treasury who determines whether to black list the contractor, supplier or the firm or individual.. Low-Average. Above $50,000: 1. CTB 2. Development Committee Officials 3. Council of Ministers (final approval) Low. Overturning contract awards.
No. Only delegated line agencies
TA 7345-VAN: PORT VILA URBAN DEVELOPMENT PROJECT Phase 2 : The Policy and Legal Reform Measures March 2011
If procurement training is assessed and planned for nationwide low, if this is delegated to line agencies average, if there is no strategy or plan high. 34. Is there a procurement accreditation or professionalization program? An externally recognized program low, a government sponsored program average, none, high 35. Are major projects identified within an agencies appropriation or budget? Yes low, no but a system in place for the ring-fencing of project funds average, neither low 36. Is the procurement cycle tied to an annual budgeting cycle? i.e. can procurement activity only commence once a budget is approved? No a medium expenditure framework is in place low, activity may start up to but excluding contract award average, yes tied to annual budget high 37. Once an appropriation or budget is approved will funds be placed with the EA or can the EA draw them down at will? Yes low, no - additional controls imposed high (such as cash release system) 38. Can an EA draw directly from a loan or imprest account or will it spend budgeted funds with the borrower claiming reimbursement? Draws directly low, from budgeted funds high 39. When an EA is implementing a project using funds from the national budget has a delay in funding significantly delayed procurement? No or not applicable low, yes high
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None. High Yes. Low Average. Budget include contract amounts but the contract award may slip to. Hence the amount is included in the next budget cycle. Yes. The funds will be with MoFT and the EA can draw the funds by getting approval from Director Yes. Low. Director or Project Manager approves and signs vouchers Not applicable. Low.
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122 Appendix 4B
Appendix 4B Executing Agency Procurement Capacity Questionnaire 1. Procurement of goods, works and consulting services is usually a key element of project implementation which, when an agency has the capacity to undertake procurement efficiently and well, will contribute to the overall project objectives. Conversely, when procurement capacity is low, it will make achieving these objectives harder. 2. The primary purpose of this questionnaire is to assist ADB in assessing the procurement capacity of an Executing Agency (EA) that will utilize ADB funds. The output from completion of this questionnaire will be a set of specific recommendations prepared by ADB relating to the implementation of the project (which may take the form of support built into the project design) and wider recommendations that do not impact directly upon the project but may assist the EA and borrower in developing procurement capacity and therefore performance beyond the scope of the project. 3. The EA will be invited to review and comment upon the recommendations made and agreement between the EA, Borrower and ADB will be reached on implementing those recommendations relating to the implementation of the project. 4. The following pages form the questionnaire which is divided into the following parts: Part A: Agency Procurement Processes, Goods and Works. Part B: Agency Procurement Processes Consulting Services. Part C: Process Control and Oversight. Part D: Records Keeping and Audit. 5. If the EA will not be expected to procure goods, works or consulting services the corresponding element of the questionnaire can be left blank. 6. Efforts have been made to design the questionnaire so that simple factual answers may be given, the onus being on ADB to ask for more information if it requires it. It is acknowledged that not all of the questions will be relevant to all EAs. When a respondent (the person completing the questionnaire) regards a question as not relevant to the EA they should state “not applicable”.
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123 Appendix 4B
Executing Agency Capacity Assessment Questionnaire Part A. General Agency Resource Assessment A.1.Is there a procurement department? A.2.What procurement does it undertake? A.3.Are the staff provided with written job descriptions? A.4.How many years experience does the head of the procurement unit have in a direct procurement role? A.5.How many staff in the procurement department are: i. Full Time? ii. Part Time? iii. Seconded? A.6.At what level does the department report (to the head of agency, deputy etc.)? A.7.Do the staff that will be involved with the procurement have English language skills sufficient to undertake international procurement? A.8.Is the number and qualifications of the staff sufficient to undertake the additional procurement that will be required under the proposed project? A.9.Does the unit have adequate facilities such as PCs, internet connections, photocopy facilities, printers etc. to undertake the expected procurement? A.10. Is there a procurement training program? Part B. Agency Procurement Processes, Goods and Works B.1.Has the agency undertaken foreign assisted procurement of goods or works recently (last 12 months, or last 36 months)? (If yes funded by whom and name of the Project) B.2.If the above is yes, what where the major challenges?
B.3.Is there a procurement process manual for goods and works?
Response No. But there is a Project Management Unit which handlesthe procurement. Goods, Services, Works Yes. Expatriatess and national staff. 16 years (Willie Watson, PWD Director) 1 (local staff) 1 (local staff) To Director, PWD and DG, MIPU Yes. Supported by international consultants. No. Current level of staff committed to different projects. No. Office equipment will need to be procured under the project. No. Yes. MCA – MCC, Outer Island Airports – AFD, Vanuatu Transport Sector Support Program - AusAID 1. Time limitations in procurement (too short or too long) 2. No guidelines/manual and Agency Contracted Procurement 3. Need to be supported by Specialist 4. Need for training and imparting of skills. No. There is a guideline for procurement
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B.4.If there is a manual is it up to date and does it cover foreign assisted procurement? B.5.Is there a systematic process to identify procurement requirements (1 year or more) B.6.Who drafts the specifications? B.7.Who approves the specification? B.8.Are there standard bidding documents in use and have they been approved for use on ADB funded projects?
B.9.Who drafts the bidding documents? B.10. B.11.
Who manages the sale of the document? Are all queries from bidders replied to in writing?
B.12.
Is there a minimum period for preparation of bids and if yes how long?
B.13. Does the bidding document state the date and time of opening and how close is it to the deadline for submission? B.14. Is the opening public? B.15. Can late bids be accepted? B.16. Can bids be rejected at bid opening? B.17. Are minutes taken? B.18. Who may have a copy of the minutes?
B.19.
Are the minutes free of charge?
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of goods and services, June 2005. NA No. Refers to project documents Consultant in the PMU Director and DG Yes. FIDIC – International Agency – Local, smaller. They are not approved for use under ADB funded projects. Consultants in the PMU do the drafting and approved by State Law Office MIPU. Yes. All communications is relayed in writing to all bidders. Civil Works 30 days for National 72 days and more for International Consulting 30 days Local Goods 2 weeks – 1 month Local 90 days International Yes. Yes. No. No. Yes. Prepared by the Secretary of theCentral Tenders Board. Copies are distributed to the Executing Agency and project management unit. Yes.
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B.20.
Who undertakes the evaluation (individual(s), permanent committee, ad-hoc committee)?
B.21. What are the qualifications of the evaluators in respect to procurement and the goods and works under evaluation? B.22. Is the decision of the evaluators final or is the evaluation subject to additional approvals? B.23. Using at least three real examples how long between the issue of the invitation for bids and contact effectiveness?
B.24. Are there processes in place for the collection and clearance of cargo through ports of entry? B.25. Are there established goods receiving procedures? B.26. Are all goods received recorded as assets or inventory in a register or similar? B.27. Is the agency/procurement department familiar with letters of credit? B.28. Does the procurement department register and track warranty and latent defects liability periods?
125 Appendix 4B
Ad-hoc currently, but the DG has recommended a permanent bid evaluation committee comprising representatives from Ministry of Finance, State Law, PWD, and PMU Consultants Law, Accounting, Engineering, and Procurement Subject to DCO and Council of Minister’s approval Local – 60 days International – 6 mos 1. Outer Island Airport project (AFD) – 135 days 2. Main Wharf (JICA) – 60 days 3. Meteorology Office – 120 days Yes. Customs, Custom clearance agencies mostly clear the goods. Yes. Yes. Asset Registry System maintained by MOFT. Yes Yes.
Part C. Agency Procurement Processes, Consulting Services C.1. Has the agency undertaken foreign assisted procurement of consulting services recently (last 12 months, or last 36 months)? C.2. If the above is yes what where the major challenges? C.3. C.4. C.5. C.6.
Is there a procurement process manual for consulting services procurement? Is the manual up to date and does it cover foreign assisted projects? Who identifies the need for consulting services requirements? Who drafts the ToR?
Yes. e.g. AusAID financed VTSSP Development of TORs, evaluation and preparing contract documents. No. NA. Need to prepare one. EA in discussion with the financier PWD with assistance from PMU Consultants
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C.7. Do the ToR followed a standard format such as background, tasks, inputs, objectives and outputs? C.8. Who prepares the request for proposals? C.9. Are assignments advertised and expressions of interest called for? C.10. Is a consultants’ selection committee formed with appropriate individuals in terms of procurement and technical expertise? C.11. What criteria is used to evaluate EOIs? C.12. Historically what is the most common method used (QCBS, QBS etc.) C.13. Do firms have to pay for the proposal document? C.14. Does the evaluative criteria follow a pre-determined structure and is it detailed in the RFP? C.15. Are pre-proposal visits and meetings arranged? C.16. Are minutes prepared and circulated after pre-proposal meetings? C.17. To who are minutes distributed? C.18. Are all queries from consultants answered to in writing? C.19. Are the financial and technical proposals in separate envelopes? C.20. Are proposal securities required? C.21. Are technical proposals opened in public? C.22. Do the financial proposals remain sealed until technical evaluation is completed? C.23. Are minutes of technical opening distributed? C.24. Who determines the final technical ranking and how?
C.25. Are the technical scores published and sent to all firms? C.26. Is the financial proposal opening public? C.27. Are there minutes taken and distributed of financial proposal opening? C.28. How is the financial evaluation completed?
C.29. Are face to face contract negotiations held? C.30. How long after financial evaluation is the selected firm to negotiate?
126 Appendix 4B
Yes PWD with Consultants Yes Yes
assistance
from
PMU
Country/regional experience, similar projects, blacklists QCBS No Yes Yes Yes To those who attended meeting, DG, CTB Yes Yes Yes Yes Yes Yes PMU, Consultant Selection Committee Evaluated individually then meetings to discuss No Yes Yes The percentage is announced in the beginning then applied to tech/financial. E.g. 80:20 Yes 1 week
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C.31. What is the usual basis for negotiation?
C.32. Are minutes of negotiation taken and signed? C.33. How long after negotiations until the contract is signed? C.34. Are advance payments made? C.35. Is there an evaluation system for measuring the outputs of consultants?
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TOR, Cost, resources, date of notice to proceed, counterparts, advance payments Yes 1 week minimum if there’s a clause Evaluated based on work requirements, payment milestones but no current system in place.
Part D. Process Oversight and Control D.1. Is there a standard statement of ethics and are those involved in procurement required to formally commit to it? D.2. Are those involved with procurement required to declare any potential conflict of interest and remove themselves from the procurement process? D.3. Is the commencement of procurement dependent on external approvals (formal or de-facto) outside of the budgeting process? D.4. Who approves procurement transactions and do they have procurement experience and qualifications? D.5. Which of the following actions require approval outside of the procurement unit or a permanent evaluation committee and who grants the approval? a) Bidding document, invitation to pre-qualify or request for proposal b) Advertisement of an invitation for bids, pre-qualification or call for expressions of interest c) Evaluation reports d) Notice of award e) Invitation to consultants to negotiate f) Contracts D.6. Is contractual performance systematically monitored and reported upon? D.7. Does the agency monitor and track its contractual payment obligations? D.8. On average how long is it between receiving a firm’s invoice and making payment? D.9. What is the standard period for payment included in contracts? D.10.When payment is made late are the beneficiaries paid interest? D.11.Are payments authorized by the same individuals empowered to approve invitation documents, evaluations and contracts? D.12.Is there a written auditable trail of procurement decisions attributable to individuals and
Each evaluator signs a statement of no conflict of interest Yes Sometimes – donors. Otherwise none. COM. No.
State of Laws for bidding documents DG of EA CTB COM EA Minister, EA Yes Yes 30 days 30 days Yes, built into the contracts No Yes
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committees? D.13.Are procurement decisions and disputes supported by written narratives such as minutes of evaluation, minutes of negotiation, notices of default/withheld payment? D.14.Is there a formal non-judicial mechanism for dealing with complaints? D.15.Is a complaints resolution mechanism described in national procurement documents? Part E. Records Keeping E.1. Is there a referencing system for procurement files? E.2. Are original contracts secured in a fire and theft proof location? E.3. Are copies of bids or proposals retained with the evaluation? E.4. Are copies of the original advertisements retained with the pre-contract papers? E.5. Is there a single contract file with a copy of the contract and all subsequent contractual correspondence? E.6. Are copies of invoices included with contract papers? E.7. For what period are records kept?
128 Appendix 4B
Yes No No Yes Yes Yes Yes Yes Yes 10 years in the office then national archive
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