By Darren Romain, CH2M HILL Senior Project Manager and Environmental Engineer

Darren Romain, CH2M HILL Senior Project Manager and Environmental EngineerIn Singaopore’s continued efforts to reduce its dependence on imported water and as part of a long-term water security program, Singapore PUB recently completed major projects that enable the collection of urban runoff water in two impounded coastal reservoirs – Punggol-Serangoon Reservoir and Marina Reservoir – and transfer to the Upper Peirce Reservoir (UPR). Chestnut Avenue Waterworks (CAWW) in Singapore treats raw water withdrawn from the UPR, which has traditionally only received catchment run-off as well as water imported from neighbor, Malaysia. However, as a result of the new reservoir transfers, the quality of water in the UPR is changing and the water treatment processes at CAWW need to be augmented to cater for this change.

CAWW was developed in two stages – Stage 1 and Stage 2, each rated at a capacity of 272 ML/d – to provide a drinking water output of 544 ML/d.  The treatment process streams operate in parallel, and with a few exceptions, are independent of each other. Modifications have recently been completed to Stage 1 to allow treatment of up to 410 ML/d of Marina Reservoir water prior to discharge into UPR. This work has not increased the drinking water output of CAWW but reduces organics and removes most of the phosphorous and suspended solids prior to discharge into UPR.

Aerial view of Chestnut Avenue Waterworks, SIngaporePUB is considering upgrading the drinking water treatment processes at CAWW to cater for future degradation of the UPR raw water quality. Originally, when the reservoir collection and transfer schemes were first envisioned, it was assumed that the salinity would increase in UPR and that the preferred treatment process would be membranes (nanofiltration or reverse osmosis), potentially followed by advanced UV oxidation. However, the anticipated salinity increase has been marginal and well within acceptable aesthetic guidelines.

Based on the data, PUB has selected the combination of ozonation and biologically active carbon contactors to be added to both the Stage 1 and Stage 2 drinking water treatment streams. The addition of the treatment process will provide enhanced biological stability of the water, provide increased pathogen disinfection, and provide better tasting water for the community.

CH2M HILL has just completed a study for PUB to locate these new processes on the very constrained site that is bounded on all sides by a national park and the UPR. We are proud to continue to support PUB and contribute to the Singapore Water Story as the island nation continues to lead the world in water resource management and sustainability.

Darren Romain is a senior project manager and environmental engineer based in CH2M HILL’s Sydney, Australia, office. Romain has more than 15 years of project management experience, with particular expertise in the area of managing large brownfield drinking water treatment upgrade projects with multiple stakeholders. He has more than 17 years experience with potable drinking water ozonation, and has been the lead designer for several drinking water UV disinfection upgrades at conventional, direct filtration, and membrane water treatment plants with specific expertise in disinfection and oxidation processes and technologies.