Two Water Supplies Department senior engineers today left for the US to study a new technique for non-destructive condition assessment of underground water mains.

The method enables inspection of the internal condition of in-service water mains and detection of leaks and defects by a closed-circuit camera and a leakage detection sensor inserted into the mains, without affecting water supply.

The engineers will participate in on-site condition assessment works in Dallas, Texas, using the new technique and evaluate the suitability of its application to Hong Kong's water supply.

They will be briefed by the Dallas Water Utilities on its leak detection programme and visit a water-treatment plant. They will visit a pressure management control valve factory and water utility companies in Newport Beach, California, to see the latest technology on pressure management and valve control.

Work on the replacement of the groups of water mains across Gloucester Road in front of Immigration Tower will start tonight. The department has completed work to detect leaks in the eight groups of underground water mains across the busy road, with no leakage detected.

Noise loggers have been installed on these water mains to enable continuous monitoring of their condition.