PUB to delve deep into 10 Singapore reservoirs

Feng Zengkun The Straits Times AsiaOne 29 May 15;

Singapore will be looking at what lies beneath its reservoirs to find out how to better maintain them.

National water agency PUB plans to conduct a soil study of 10 reservoirs around the island to better understand how water moves between the reservoirs, and the groundwater system immediately beneath them.

In tender documents outlining the first-of- its-kind project, the agency said the work would help improve the management, maintenance and long-term planning of Singapore's reservoirs.

Experts told The Straits Times that the agency would be able to estimate, for example, how quickly and how much water seeps from the reservoirs into the groundwater system.

In response to queries, PUB said it carries out routine samplings of sediments at the reservoir bed surfaces every three to five years.

"This is the first time we are conducting the soil studies at depths below the bed surfaces, to have a more comprehensive mapping of the physical and chemical characteristics of the soil sediments," a spokesman said.

The project is expected to start in August and be completed within six months.

According to the tender documents, the agency wants a total of 21 boreholes dug at the reservoirs.

These are the Kranji, Pandan, Sarimbun, Lower Seletar, Punggol, Serangoon, Marina, Poyan, Tengah and Jurong Lake reservoirs.

The samples will be taken from the reservoir beds, at 0.9m, 1.9m, 2.9m below the bed, and, if possible, at every 3m, up to a depth of about 30m.

Laboratory tests will be run on the soil samples to find out their moisture content, the size of the particles in the soil, and other characteristics.

Assistant Professor Ku Taeseo, from the National University of Singapore's Department of Civil and Environmental Engineering, said: "In terms of the natural water cycle, groundwater is a kind of long-term reservoir.

"Basic soil characterisations are important to understand seepage issues, such as the flow pattern, speed and amount."

He added that PUB might also want to check the water's movement by extensive monitoring of the groundwater.

FIRST OF ITS KIND

This is the first time we are conducting the soil studies at depths below the bed surfaces, to have a more comprehensive mapping of the physical and chemical characteristics of the soil sediments.

- A PUB spokesman, on the soil study project