Singapore: Building blocks of good drainage

Joy Fang my paper AsiaOne 30 Nov 10

Singapore has done well in managing its water resources, said Mr Baur, especially with regard to its fresh-water supply. He said, however, that Singapore can do more in terms of environmental solutions such as increasing biodiversity and wildlife

NEW technology that makes low-lying land "harvest" rainwater more effectively is being implemented at two locations here. The technology uses modular units to create shallow depressions in the land called "swales".

Swales are dug in soil patches next to pedestrian footpaths, and are not clearly visible because they are usually covered with vegetation such as grass and plants.

The modular units deployed in the new technology are cubes measuring 1m on each side.

Shaped like a planter box, each unit contains several layers of soil that help to filter and treat rainwater that flows into the swale.

Existing swales were created by digging trenches in a patch of land and then refilling them with different layers of soil, said Associate Professor Tan Soon Keat, deputy executive director of the Nanyang Technological University's (NTU) Nanyang Environment & Water Research Institute (Newri).

This means that if there is a blockage in the system, the soil has to be dug up again to locate the problem.

This may cause the sides of the trench to collapse, said Prof Tan.

In contrast, the new system is more adaptable. Each module can be removed and replaced individually like building blocks, without disturbing the entire system, explained Prof Tan.

This makes maintenance an easier task that will likely be cheaper than current processes, he added.

A team in Newri is working with a statutory board to test the new technology at two areas here, with each location's swale spanning about 50m.

Prof Tan declined to reveal details like the locations of the new swales, but said that the projects are being carried out in public areas such as parks.

Older swales can be found in Sengkang West Way, Sentosa Cove and on the grounds of some condominiums.

Prof Tan stressed that the swales are not meant to take over the role of concrete canals.

Rather, they help to slow down the flow of water into the main drainage system in the event of flooding.

He was speaking to reporters at a seminar that discussed Germany and Singapore's storm-water management for urban sustainability, held yesterday at NTU's One North campus.

It was attended by around 100 Singapore and German industry participants.

Seminar speaker Tobias Baur, director of the Singapore office of German-based landscape firm Atelier Dreisteitl, said Germany has a long history of storm-water management.

His company is working on a few pilot projects with national water agency PUB to retrofit and upgrade drainage systems in residential areas.

Singapore has done well in managing its water resources, said Mr Baur, especially with regard to its fresh-water supply.

He said, however, that Singapore can do more in terms of environmental solutions such as increasing biodiversity and wildlife.