Feasibility of Urban Storm Runoff As an Additional Freshwater Source: Singapore As a Case Study
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Feasibility of urban storm runoff as an additional freshwater source: Singapore as a case study By Deh Chien Chen A thesis submitted for the degree of Doctor of Philosophy in the Faculty of Life Sciences Centre for Environmental Policy Imperial College of Science, Technology and Medicine, London February 16, 2010 Abstract Freshwater is a finite resource. Faced with this challenge in the 21st century, there is an urgent need to augment existing sources of freshwater with sustainable alternatives. By adopting innovative demand management, water efficiency and conservation strategies, smart economics and advanced water technologies, water sustainability can be achieved as well as water security. The thesis posits that a decentralised system, like rooftop RWH, is feasible as an additional freshwater source running parallel to supplement and/ or complement the existing centralised mains water supply system for non-potable use even in high technology countries. Singapore, an urban city with abundant rainfall in a developed country context, is selected as a case study. As more than 80% of Singapore population lives in high-rise public housing, the HDB flats, rooftop RWH would augment the freshwater supply for urban storm runoffs that are discharged to the sea and are not collected in the stormwater collection ponds or reservoirs. Considerable potable water and cost savings would result as at least 25% of the potable mains water presently used for toilet-flushing, irrigation and floor-washing purposes could be substituted by rainwater. The centralised mains water supply system, as the main freshwater supply in socio-economic terms, is questioned as roofwater, with comparative good water quality, can be for non-potable use and thus supplement to meet the increasing water demand. RWH being a decentralised system, with numerous scattered water points throughout a city, has greater flexibility and autonomy and is less vulnerable to disruption in a distribution system, biological warfare and terrorism. For RWH to be successful, it must be carefully planned and designed to meet specific needs and conditions. In addition to enhancing technical guidelines, a combination of legislation, together with incentives, taxes and penalties helps to promote RWH and to maximize the benefits of implementing these systems. RWH is an under-used technology and strategy that can provide multiple benefits. When successfully implemented, RWH in the Singapore model can help close the gap in the total water cycle. It shows that even in a highly developed technological country like Singapore, there is room for a low but environmentally sound technology like RWH to play an important and relevant role. It is hoped that the lessons learned in Singapore can be replicated in other similar situations on a global scale. ii Acknowledgements I would like to express my gratitude to my supervisors, Prof. Cedo Maksimovic and Dr. Nick Voulvoulis, for their continuous advice, encouragement, assistance and critical reading of this thesis. For their friendship and help in providing all the information available for the Singapore case studies, my special thanks are due to: i) Harry Seah and his colleagues from the Public Utilities Board, Singapore, ii) Dr. Johnny Wong, Alan Tan Hock Seng and their colleagues from the Housing Development Board, Singapore, iii) V. Balasubramaniam and his staffs from the Sembawang Town Council, iv) Rajoo Shanmugan and Lily Teo from Temasek Polytechnic, v) Fong Kok Wai, Teng Kok Heng and their colleagues from the Civil Aviation Authority of Singapore, vi) Allen Ang and Nelson Hah from City Development Limited, vii) the various departmental heads from the National Park Board in providing data for the case studies at Sungei Buloh Wetland, The Chinese Garden and Fort Canning Park, and viii) Professor Shuy Eng Ban from the Nanyang Technology University of Singapore. I would also like to thank members of my group in CEP at Imperial College for their friendship and sharing of both good and bad moments during this work, and our numerous lunches, dinners and parties together over the last four years: Danelle Mohammed, Eleni Iacovidou, Khareen Singh, James Treadgold, James Bone, Ho-Sik Chon, Sally Donovan, Maria Taoussi, Dieudonne-Guy Ohandja, Claire Hunt, Olwenn Martin, Pan Jilang, Rebecca Mckinlay and Victoria Rowsell. I am also extremely grateful to my mother in Singapore for her unwavering faith in my ability, coupled with her support and patience when I was collecting data in Singapore. It would have been much more difficult if she had not been in Singapore, as I had the comfort of a home and food every day for three whole summers (2006-2008). This thesis is dedicated to my late father, Sing Wu Chen. He wanted me to do a PhD when I graduated from US law school in 1989. It is now completed – twenty years later. iii Glossary of terms A$ Australian dollar ABC Active, Beautiful, Clean ABRI Architecture and Building Research Institute ASEAN Association of Southeast Asian nations BCA Building Construction Authority BMPs Best Management Practices CAAS Civil Aviation Authority of Singapore CASBEE Comprehensive Assessment System for Building Environmental Efficiency CDM Camp Dresser & Mckee, CO2 carbon dioxide Coeff coefficient Cum cumulative DIN The German Institute for Standardization DTSS Deep Tunnel Sewerage System EA Executive apartment EEWH Ecology, energy saving, waste reduction and health EH Executive house EM Executive maisonette ENV Ministry of Environment EPA Environmental Protection Agency EST Environmental sound technology EUR Euro FRP Fibre reinforced panel GST Goods and services tax ha hectare HDB Housing Development Board HIP Home Information Pack hr hour hrs hours IP input IRAS Inland Revenue Authority of Singapore IT Information Technology IUWM Integrated urban water management IWRM Integrated water resource management JTC Jurong Town Corporation L litre LCC Life cycle cost Lcd litre per capita per day LEED Leadership in Energy and Environmental Design lit litre LTA Land and Transport Authority LUC Land Use Code m metre m3 cubic metre MEWR Ministry of Environment and Water Resources mgd million gallon a day min minutes iv MLTM Ministry of Land Transport and Maritime Affairs mm millimetres MND Ministry of National Development MOE Ministry of Environment MOF Ministry of Finance mth month NEA National Environmental Agency NDB National Development Board NParks National Parks Board OECD Organisation for Economic Co-operation and Development OP output 3P People-private-public sector % percent PAH polycyclic aromatic hydrocarbon PPP Private-public-partnerships PR People for rainwater PRV Pressure reducing valves PVC Polyvinyl chloride PUB Public Utilities Board PWD Public Works Department RF rainfall R&D Research and development RM Malaysian Ringgit RWCS Rainwater Cistern System or Rainwater Catchment System RWH Rainwater harvesting S$ Singapore dollar SAF Sanitary appliance fee SAW San Antonio Water System SH shop SWRO seawater reverse osmosis UDM Urban drainage modelling UFW Unaccounted-for water UK United Kingdom UN United Nations UNEP United Nations Environmental Protection URA Urban Redevelopment Authority US United States of America US$ United States dollar UV ultraviolet VFD Variable Frequency Drive WBF Waterborne Fee WCT Water Conservation Tax WELS Water Efficiency Labelling Scheme WHO World Health Organisation WRA Water Resources Agency WRAS Water Regulations Advisory Scheme WSUD Water Sensitive Urban Design (WSUD) YAS yield after spillage YBS yield before spillage yrs years v Table of contents Abstract.............................................................................................................................ii Acknowledgements..........................................................................................................iii Glossary of terms.............................................................................................................iv Chapter 1 Introduction ................................................................................................. 1 1.1 Background ........................................................................................................ 1 1.2 Problem statement .............................................................................................. 5 1.3 Research aim and objectives .............................................................................. 6 1.4 Methodology ...................................................................................................... 7 1.5 Outline of the thesis ........................................................................................... 7 1.6 Original contribution to research ....................................................................... 9 1.7 Papers produced ................................................................................................. 9 Chapter 2 Legislative and non-regulatory framework ............................................... 11 2.1 Introduction ...................................................................................................... 12 2.2 Existing building codes and guidelines ........................................................... 12 2.3 Non-regulatory framework .............................................................................. 20 2.4 Policy for rainwater harvesting development .................................................. 22 2.5 Discussion .......................................................................................................