lim- l seletar bedok water scheme adelaide 12may11...bedok collection pond (2) tss and bulk organic...
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Mong Hoo Lim
Deputy Director, PUB, Singapore
Singapore’s experience in Stormwater Harvesting: The Lower Seletar / Bedok Water Scheme
Singapore’s experience in Stormwater Harvesting: The Lower Seletar / Bedok Water Scheme
12 May 2011 2
2. 2. SungeiSungei SeletarSeletar / / BedokBedok Water SchemeWater Scheme
1. 1. Overview of Singapore Water SupplyOverview of Singapore Water Supply
4. 4. Water Quality of Storage ReservoirsWater Quality of Storage Reservoirs
3. 3. StormwaterStormwater QualityQuality
Outline
5. 5. Important FactorsImportant Factors
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Singapore
Land Area 710 km 2
Population 5 mil
Average Annual Rainfall 2,400 mm
Average Water Demand 1.6 mil m 3/day
Country Information
Singapore
Overview
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“To deliver and sustain a clean and healthy environment and water resources for all in Singapore.”
“To ensure an efficient, adequate & sustainable supply of water”� Clean Water
“To ensure a sustainable quality environment in Singapore”
� Clean Land
� Clean Air
� Public Health
A Statutory Board constituted under
the Public Utilities Act 2001 to provide
integrated water supply, sewerage and
drainage services
PUB’s Vision and MissionOverview
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Rain Sea
Direct Non-
Potable Use
PUB Manages the Complete Water CycleFrom drainage of storm water to sourcing, collection, purification and supply of drinking water,
treatment of used water and turning it into NEWater
NEWater
Overview
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Water Resource Management
Ensuring a diversified and sustainable supply of water for Singapore with the Four National Taps Strategy
Overview
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Location map of Lower Seletar and Bedok stormwater harvesting systems
40 Km 2
22 Km 2
Sungei Seletar / Bedok Water Scheme
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Drop inlet diversion structure
Sungei Seletar / Bedok Water Scheme
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Main pump
motor
Pumping station
Reservoir
Wet well
Start pumping!
grating
Downstream canal going to sea
Drainage pump
Start Pumping!Stop pumping!
Rain comes
Water in canal rises
Water overflow thru’ grating into inlet chamber
Water flow into the pond
Drainage pump starts to remove 1 st
flush
Water continue to flow in and water level rises
Main pump starts to pump water to reservoir
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Barrage gate lateral diversion structure
Sungei Seletar / Bedok Water Scheme
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Stormwater Quality
• Sources of pollutants– Surface itself (eg, roads and litters)– Motor vehicles (leakage of fuel, oil, and coolants, worn-off portions
of tires, clutches, and brake linings, and particulate exhausts)– Atmospheric ‘fallout’– Spills and industrial wastes
• Parameters of concern– literature review of SW studies: nutrients, metals, organic matter,
suspended solids, PAHs– Other important parameters include:
– Microbiological parameters, eg, Faecal coliforms, E coli, Enterococci– Contaminants of emerging concern, eg, PPCPs, EDCs etc.
���� Grouped under 6 categories:(1) Nutrients, (2) TSS and bulk organic, (3) Metals, (4) organic contaminants, (5) microbiological parameters, (6) contaminants of emerging concern
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Approach to Water Quality Evaluation
• Fate of pollutants in SW harvesting– A direct catchment stream
(L Seletar catchment)before, during and afterstorm
– A SW collection pond (Bedok catchment)before, during storm,‘first flush’ and waterpumped to reservoir
• 20 years’ WQ data– Lower Seletar & Bedok
Reservoirs Vs MacRitchie Reservoir
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Lower Seletar direct catchment stream
(1) Nutrients
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Lower Seletar direct catchment stream
(2) TSS andbulk organic
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Lower Seletar direct catchment stream
(3) Metals
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Lower Seletar direct catchment stream
(3) Metals(cont’d)
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Lower Seletar direct catchment stream
(3) Metals(cont’d)
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Lower Seletar direct catchment stream
(4) Organiccontaminants(63 comp’ds)
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Lower Seletar direct catchment stream
(5)Microbiologicalparameters
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Lower Seletar direct catchment stream
(6) Emerging contaminants
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Lower Seletar direct catchment stream
(6) Emerging contaminants (cont’d)
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Bedok Collection Pond(1) Nutrients
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Bedok Collection Pond(2) TSS and bulk organic
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Bedok Collection Pond(3) Metals
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Bedok Collection Pond(3) Metals (cont’d)
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Bedok Collection Pond(3) Metals (cont’d)
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(4) Organiccontaminants(63 comp’ds)
Bedok Collection Pond
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Bedok Collection Pond(5) Microbiological parameters
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Bedok Collection Pond
(6) Emerging contaminants
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Bedok Collection Pond(6) Emerging contaminants (cont’d)
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Bedok Collection Pond(6) Emerging contaminants (cont’d)
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Bedok Collection Pond
(6) Emerging contaminants (cont’d)
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20 years’ WQ data(1) Nutrients
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20 years’ WQ data(2) TSS and bulk organic
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20 years’ WQ data(3) Metals
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20 years’ WQ data(3) Metals (cont’d)
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20 years’ WQ data(4) Organic contaminants
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20 years’ WQ data(5) Microbiological parameters
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20 years’ WQ data(6) Emerging contaminants
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20 years’ WQ data(6) Emerging contaminants (cont’d)
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• Well coordinated land use planning and integrated catchment management– close consultation among all relevant government agencies
(HDB, URA, JTC, NEA, MND etc)
• Effective pollution control measures– Termination of pig-farming and other agricultural activities– domestic wastes, waste-collection centres
• Separation of stormwater from sewage• Integrated water and wastewater management
– $400m spent to reline sewers to prevent leaks
• High dilution factor– (2400mm of rainfall pre year)
Important Factors
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• The pollutants loadings in the Lower Seletar / Bedokstormwater runoff are low
• The water quality of Lower Seletar and Bedok stormwaterstorage reservoirs is good and is comparable to that of a reservoir in the protected catchment (i.e., MacRitcheReservoir)
• Effective pollutant source management is key to the success of stormwater harvesting
Conclusion