At 6.4km long, it might be the longest wall in Singapore - and it is underground. That is what national water agency PUB has had to build to prevent pollution at Serangoon Reservoir for a unique project in Singapore: The transformation of a former landfill into a wetland.
On Saturday, Lorong Halus, a 234-hectare area along the eastern bank of Singapore’s 17th reservoir, will be officially opened under the Active, Beautiful and Clean waters programme.
Above ground, it provides the public with another nature attraction; species such as dragonflies and kingfishers are already thriving in the environment. Below ground, a cutting-edge landfill remediation system is hard at work so that rainwater passing through the waste buried in the landfill will not seep into the reservoir.
This water, known as leachate, is instead redirected to the wetland for treatment, PUB deputy director (catchment and waterways) Goh Chong Hoon told reporters this week. On average, 200 cu m of leachate is piped out daily by the 125 pumps built along the reservoir to an equalisation tank and aeration lagoons for treatment. The landfill water is then transferred to a sedimentation tank to remove any suspended materials.
After these steps, the leachate is ready for the main treatment process done by the wetland itself. From the sedimentation tank, the water will flow to five reed beds and be purified by plants such as the cattail and papyrus sedge.
The 10-day treatment process ends after the leachate is transferred to five polishing ponds for the plants to absorb more nutrients from it before the water is discharged into the sewer system.
The three-year project to transform Lorong Halus costs around S$47.7 million. A 150m pedestrian bridge connects the wetland to neighbouring Punggol Promenade that includes a bicycle trail, lookout points and food and beverage facilities. On Saturday, the riverside walk at the promenade will be officially opened.
