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Enhancing Drains to Cope with More Rain

30 November 2017

Enhancing Drains to Cope with More Rain

The day-to-day work of drainage engineers in PUB involves coming up with ingenious solutions to tackle varied challenges in drainage projects, which are often massive and complex. This includes encountering hard rock during excavation, diverting underground services, carrying out concurrent work activities within tight spaces onsite and labouring eight storeys under​ground. 

The media was given a glimpse of this exciting challenges at a briefing cum visit to the Bukit Timah First Diversion Canal (BTFDC). 

Drainage Improvement
Ongoing works at Bukit Timah First Diversion Canal – Phase 3 (Holland Green to Clementi Road)

Built in 1972, the BTFDC runs 3.2km long, from Bukit Timah Road near Maple Avenue to Clementi Road. Its expansion works is ongoing and when completed in 2018, will give the upper Bukit Timah catchment more flood protection. 

BTFDC runs through unique and historically-rich terrain. A section of the canal goes through Military Hill and the conventional approach of open trench digging cannot be used. Instead, C&W engineers have to use tunnelling to create two new tunnels under the hill. These new tunnels, the size of MRT tunnels, will supplement the existing tunnels in conveying more rainwater. 

Drainage Improvement
As part of the Bukit Timah First Diversion Canal expansion, two new tunnels were created to supplement two existing tunnels under the Military Hill. Above picture shows one of the new tunnels.

With upgrading works taking place in a “live” canal, engineers have to ensure that BTFDC continues its function of channelling stormwater away quickly, and its drainage capacity is never compromised.

Extensive Investment in Drainage Infrastructure

The Government has spent some $1.2billion on drainage improvement works islandwide since 2011 to increase flood protection for Singapore. Drainage projects at 325 locations have been completed over the past 6 years. 

PUB is preparing for more intense rainfall and the frequency of such rain events to happen more often.  In the next 2 to 3 years, the Government plans to spend a further $500 million to upgrade more drains, and the public can look forward to drainage improvement works commencing at 16 locations in the coming year. 

There are also ongoing drainage projects taking place at 75 locations. Besides BTFDC, these include Sungei Pandan Kechil, Stamford Detention Tank and Stamford Diversion Canal.