Valerie Tan Channel NewsAsia 11 Jul 11;
SINGAPORE: Rain water usually goes to the drain first after a downpour, but not along a stretch of road at the Dawson housing estate in Singapore.
Under a lush landscape of plants are what engineers call bio-retention basins, built earlier this year, to collect, and more importantly, clean rainwater.
Tay Bee Choo, Head of the Landscape Unit with the Housing & Development Board (HDB), said: "As the water runs towards these plants, these plants, have some fur, hairiness to it. It helps to trap silt. Then as the water settles into the pit, the roots in this pit will absorb the nutrients that is dissolved in the water."
What is then left is clean rainwater, which is collected and directed into the main drain.
Ms Tay added: "If we have more than an hour of rain, and the basin is full, the excess rain water will have a chance to flow into sumps. It's designed such that it is just below the level of the road and the footpath."
Even though man-made, these systems are essentially letting nature do its job by having the plants clean the water. The idea is not new and unique to Singapore, as it has been implemented in countries like Costa Rica, America and Australia.
But it is now adapted to Southeast Asia's tropical climate, with different soil and plants like the purple fountain grass.
Ms Tay said: "We barely need maintenance because if we choose the right type of plants, the only time you need to come in is when the plants overgrow, then you may need to trim it down."
There are now plans to build more of these basins in other parts of Singapore, starting with new roads and towns like for example, Choa Chu Kang.
-CNA/ac
