PUB delves into underground reservoirs

Singapore could soon be digging deep for an answer to its water challenges.

National water agency PUB is looking into creating underground reservoirs to get around the space crunch above ground, said Minister for the Environment and Water Resources Vivian Balakrishnan yesterday.

Tapping on such structures will also help the city better deal with the effects of climate change, such as more intense rain and prolonged dry spells, as excess water can be stored and used when needed.

"In Singapore, we receive an average of about 2.4m of rainfall a year... In theory, we should not be short of water... The real limiting factor is not rainfall, but land," said Dr Balakrishnan at the opening of the inaugural Singapore International Water Week Technology and Innovation Summit yesterday.

The two-day water conference, which focuses on research and development, is a prelude to the Singapore International Water Week next year.

The underground drainage and reservoir system is likely to have three key components: Tunnels to channel stormwater below ground, caverns for water storage and a pumped storage hydropower system, which can convert energy from water flowing into underground caverns to electrical energy. This can then be used to pump the water back to the surface.

Such systems have long been championed by experts here as solutions to weather fluctuations and land scarcity.

One of them, Lui Pao Chuen, a National Research Foundation adviser who spearheaded research into Singapore's underground ammunition facility, noted: "One third of Singapore is made up of granite rocks, which are very strong, and rock caverns for underground reservoirs can be constructed there."

Chua Soon Guan, PUB's deputy chief executive, said that a tender for a two-year feasibility study on building such a system will be called in the next few months. Expected to be completed at the end of 2017, it will include geological surveys on soil and rock properties, and look into the design options.

William Yeo, PUB's director of Policy and Planning, stressed that it will work with relevant agencies and stakeholders to ensure that the surveys are "conducted with care and sensitivity to the environment".

Geological studies are essential since the underground storage reservoir must be built on rock mass instead of softer soil, which may not be able to support it, said Chong Kee Sen, president of The Institution of Engineers, Singapore.

Tan Soon Keat, director of the Nanyang Technological University's Nanyang Environment and Water Research Institute, added that building in a rocky area would also ensure that there is less water loss and would prevent the water from being contaminated by soil minerals.

PUB would not comment on possible locations or other details, but the three experts believe it could be located in the central or north-eastern part of Singapore.

audreyt@sph.com.sg

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