Cause of Water Pipe Leakage at Somerset Road on 16 January 2018

Ms Joan Pereira asked the Minister for the Environment and Water Resources (a) what is the cause of the water pipe leak at Somerset Road on 16 January 2018; (b) when was the pipe last checked as part of PUB's routine maintenance; and (c) what is the impact of continuous heavy rainfall on the underground soil where this water pipe is laid.

The water pipe leak at Somerset Road on 16 January 2018 was due to stress to the pipe caused by uneven soil settlement. We have isolated the leaking section of the pipe and put the rest of the pipeline back in service. The affected stretch of pipeline is in the process of being replaced under the Public Utilities Board's (PUB's) Pipeline Renewal Programme.

As part of its operation and maintenance regime, PUB carries out checks for leaks on its entire pipe network at least once a year, or more frequently where necessary. The pipe at Somerset Road, which is made of cast iron and laid in 1973, was last checked for leaks in December 2017, with no leaks found. We have not observed any correlation between rainfall and the number of leaks.

When leaks occur, PUB seeks to fix them in the shortest time possible, as permitted by site conditions while minimising the disruption to customers and the public. PUB officers need time to identify the pipe and the valves that need to be shut so as to isolate the leak, identify the customers who are potentially affected, and set up the appropriate alternative supply provisions. For the leak at Somerset Road, temporary supply connections to these customers were set up in tandem with the repair works to limit the disruption to the public. The repair works had to proceed carefully due to the need to minimise road closures and the presence of several other buried services belonging to the electrical and telecommunications companies near the site. PUB worked together with these companies to ensure that its repair works did not affect other critical services.

To reduce the risk of pipe leaks, including those caused by uneven soil settlement, PUB has been laying pipes made of more resilient materials, such as ductile iron and steel, and has adopted enhanced pipe-laying practices, such as pipe bedding, for better pipe support. Furthermore, we have put in place regulations to ensure that contractors take proper measures to prevent damage to our pipelines during construction activities.

Besides these measures, PUB proactively replaces older pipes or pipes which are in less satisfactory condition under its Pipeline Renewal Programme and is targeting to replace 50 kilometres (km) of such pipes this year, a 20-km increase from last year.