The first storage caverns will be ready by the first half of 2013, said JTC Corporation during a briefing yesterday.

JTC has awarded the building contract to South Korea's Hyundai Engineering and Construction - over the only other bidder, fellow South Korean firm SK Engineering and Construction.

The tender was called in late 2007 but the complexity and design of the project led to delays, said a JTC spokesman.

Its cost has also risen, above the $700 million expected earlier.

Japanese firm Sato-Kogyo has already built two access shafts and start-up galleries in the initial phase for the storage caverns, work that has cost about $50 million.

The media yesterday visited part of the rock cavern under the seabed of the Banyan Basin via an access shaft that went as deep as 132m below ground level.

Workers will use a technique that drills and blasts sedimentary rock to build the cavern, which will be used to store liquid hydrocarbons such as crude oil, condensate, naphtha and gas oil.

The first phase consists of 8km of tunnels and five caverns.

Together, they will contain nine storage galleries, each about nine storeys high and big enough to accommodate the water from more than 64 Olympic-sized swimming pools.

Read the full story in Friday's edition of The Straits Times.