Water wonders: wetland and ponds in Singapore parks

A special wetland and dry ponds are among the award-winning water features at two parks
tay suan chiang Straits Times 12 Jul 10;

Housewife Tan Bee Lian watches over her four-year-old grandson while he dabbles gleefully in water at a park.

A resident at Woodlands Drive 62, she has been visiting the seven-month-old park in the evenings. Called Greenwood Sanctuary @ Admiralty, it is a five-minute walk from her home.

The pond - one of 11 in the park - is a hit with the boy, Jun Jie. Madam Tan, 63, says: 'The water is not crystal clear but I don't mind him dipping his toes in it.'

Certifying the cleanliness of such water spots is as easy as ABC. Well, sort of.

Since 2006, national water agency PUB has had an Active, Beautiful, Clean (ABC) Waters programme that encourages the cleansing of rainwater and supports human interaction with waterways here.

Last week, which was also Singapore International Water Week, the first ABC Waters certificates were handed out to 14 projects around Singapore. Greenwood Sanctuary @ Admiralty was one of them.

Ms Angela Koh, PUB's assistant director for catchment and waterways, says the certification scheme recognises developers who 'take the effort to introduce ABC Waters design features into their projects'.

Under the 'Active' category, points are awarded for facilities that allow people to get close to the water. 'Beautiful' refers to the project's aesthetics, how surface drainage spaces are integrated with nature as well as the plant variety and biodiversity of the project. And 'Clean' refers to the measures that have been put in place to treat rainwater.

Other projects that received the certificate were Sengkang Riverside Park, the upcoming boardwalk from VivoCity to Sentosa and public residential project Sky Terrace @ Dawson.

Dry ponds fill up after rain

Greenwood Sanctuary @ Admiralty

This 1.5ha, $2.1-million park at Woodlands Drive 62 was opened to the public in January. Developed by the Housing Development Board (HDB), it is the first eco-park in Singapore with dry ponds and swales.

While conventional ponds are constantly filled with water, dry ponds fill up only after it rains. Swales are shallow depressions on the ground.

Unlike other parks which have concrete drains for rainwater to run off, this park has none. Instead, the swales lead the rainwater to the 11 dry ponds that are scattered around the park.

A HDB spokesman says that in place of concrete drains, the swales give the park a more natural look. She adds that the park's topology has contours that channel rainwater to the swales.

When it rains, water runs off the surrounding ground to the dry ponds and filters to underground percolation tanks wrapped in permeable membranes. On rainy days, only eight ponds can be seen as a few are connected.

In dry weather, the rainwater collected will slowly permeate the surrounding land to keep the ground moist. This helps provide water for the park's plants.

The spokesman says the board can save $500,000 in construction costs by introducing swales and dry ponds instead of building concrete drains. 'The savings are, in turn, spent on better quality play equipment, sculptures and plants in the park,' she adds.

Signs on how the swales and dry ponds work have also been put up so visitors can better understand the green features.

Recycled rubber mulch is used for the running track to allow rainwater to percolate into the ground.

Wetland and wild

Sengkang Riverside Park

For most families, especially those with kids, a visit to the Sengkang Riverside Park in Anchorvale Street is not complete without a stop by its pond. There, they toss in bits of bread to feed its inhabitants such as soft-shell turtles.

But the 21ha park, which opened in February last year, has also drawn non-human visitors. Birds, such as the purple heron and the collared kingfisher, which were previously not seen in the area, now drop in to feed on the fish in the pond.

A spokesman for the park's developer, National Parks board (NParks), says it had specially constructed a wetland, a first of its kind in Singapore. The park's design of contours and slopes lets rainwater flow naturally into the pond, which is divided into different sections.

In the sedimentation basin, larger particles such as soil sink to the bottom. The water then flows into a main section where micro-organisms in it are absorbed by aquatic plants via their roots. This natural process treats the water by further clearing it of pollutants. The water is then pumped out to irrigate the park's flora.

NParks sees the set-up cost of about $300,000 as an investment: The pond enhances the area's biodiversity and rainwater is recycled. In the long run, it saves water.