PUB team to study use of groundwater

SINGAPORE - Singapore has ramped up efforts to study extracting its underground water for use.

National water agency PUB has formed a team of international experts to advise it, and will dig its first exploratory monitoring wells in the next few months.

It is interested in the subterranean Jurong rock formation in western Singapore, which could hold water-bearing layers of rock called aquifers.

Even if Singapore is unable to extract substantial water from them regularly, such aquifers could act as "water banks" for drought periods, said PUB chief technology officer Harry Seah.

While there is "no timeline" for when this water could contribute to Singapore's supply, the exploratory efforts will help to prepare the country, he said.

"We are building up our expertise in the field... and if groundwater does become feasible, we will have a ready team to manage the groundwater resource," he said.

The PUB plans to install 20 to 30 monitoring wells in western Singapore and then monitor the flow of water through them for six to 12 months.

These wells will be about 5cm wide and 10m to 20m deep. Their locations are being worked out, but likely options include green verges alongside roads and other public areas.

The answers sought include where rainwater goes after it seeps into the ground.

"For example, we want to know how much of it goes vertically down into aquifers, and how much horizontal movement there is instead," said Mr Seah.

This information will be useful when Singapore looks into how much water is available, how much of it can be extracted safely and the rate of extraction that would allow rainfall here to naturally replace the removed water.

To speed up the study process, PUB has asked six experts around the world for help. They include: Lord Ronald Oxburgh, a noted geologist and geophysicist; Professor Ken Howard, president of the International Association of Hydrogeologists and an expert in urban groundwater management; and Mr Roy Herndon, chief hydrogeologist at the Orange County Water District in California, which has been extracting groundwater for decades.

Although he played down suggestions by reporters that underground water could be Singapore's fifth tap - after imports from Malaysia, used water and treated seawater and rainwater - Mr Seah said that there is always urgency for the PUB to explore new ideas.

The PUB studied underground water in eastern Singapore's old alluvium geology in the 1990s, but the data from the technology and method used then did not give the agency "adequate confidence" that extracting the water would be sustainable or safe.

"As Singapore progresses, the water demand will keep growing," he said. "If we continue with business as usual, the energy needed will grow much faster as we ramp up desalination and Newater (used water) to meet demand. It's not sustainable."

While the PUB has embarked on research to reduce the energy needed for water treatment, "groundwater is freshwater", said Mr Seah.

"If we have abundant rainwater, we can inject some into the ground, increase our storage... extract the water to meet our demand and give us more buffer for drought."

This article by The Straits Times was published in MyPaper, a free, bilingual newspaper published by Singapore Press Holdings.

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