Reservoirs, power plants and other facilities such as landfills could be put together beneath the ground in order to save precious land, under an option to be studied by the government.
The move could bring other benefits, with heat and energy from one plant potentially being used to run another.
A reservoir can also generate hydroelectric power if water is pumped up to a height and allowed to cascade downwards.
The Ministry of National Development is to look at the costs and benefits of clustering the facilities – which also include desalination and incineration plants – at specific sites such as Tuas.
The research, which may be the most extensive on the subject to date, will help the government decide whether to go ahead and build, said a spokesman for the ministry. A tender was called for the study late last month, and a site briefing for interested parties will be held on Tuesday.
The consultants hired will work out the cost, construction time, environmental impact, and technical, operating and maintenance requirements. Their final report will be due at the end of next year.
Going underground would save precious land, according to a key recommendation contained in the Economic Strategies Committee’s report in 2010. It called for the development of an underground masterplan and a subterranean land rights and valuation framework.
A dedicated geological office was set up in 2010 by the Building and Construction Authority, but even before that, subterranean Singapore was thriving.
Most of its below-ground infrastructure, such as the Common Services Tunnel for utilities and the MRT rail network, is less than 20 meters down, but the Jurong Rock Cavern for oil storage is at a depth of 130m.
Other studies, such as one by the Society for Rock Mechanics & Engineering Geology, have already identified potential sites. For example, water-storage caverns could be sited at Bukit Batok and Bukit Gombak, in the tough Bukit Timah Granite formation that makes up about one-third of Singapore’s surface area.
And the sedimentary rock of the Jurong Formation could house warehouses at Mount Faber, propane storage at Pandan and an underground science city, already being studied by industrial developer JTC Corporation, at a 20ha geological formation beneath Kent Ridge.
Asked about safety and pollution concerns, rock-mechanics expert Zhao Jian of the Swiss Federal Institute of Technology in Lausanne pointed out: “Underground caverns are much safer against earthquakes than above-ground buildings, and pollution can be contained easily in caverns compared to above ground.”
As for flood protection, it is possible to design floodgates and diversion tunnels. Underground caverns are also generally more secure for military and energy installations such as Singapore’s underground ammunition storage facility, he added.
Some types of underground installations have already been adopted in other countries. For instance, a hydropower station in Wales uses water rushing downwards to generate electricity, while in Norway, caverns in hard bedrock are used for drinking water storage.
Underground infrastructure does not come cheap – the first phase of the Jurong Rock Cavern, Singapore’s first underground oil storage project, cost S$890 million (US$714.46 million) to build. But with land increasingly scarce, JTC is already exploring the possibility of a subterranean multi-utility hub for the One-North research and business park in Buona Vista.
Other experts, such as former chief defense scientist Lui Pao Chuen, have previously suggested recouping part of the cost by selling excavated rocks for construction works.
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