Canal to ease flooding on Orchard Road to be completed by 2018

The Stamford Diversion Canal will channel water from Stamford Canal to the Singapore River, supported by a new detention tank on Tyersall Avenue which will be in operation by early next year.
Angela Lim Channel NewsAsia 9 Jun 16;

SINGAPORE: A new diversion canal to prevent flash floods on Orchard Road will be completed by early 2018, national water agency PUB said on Thursday (Jun 9).

The Stamford Diversion Canal will channel water from Stamford Canal to the Singapore River, supported by a new detention tank on Tyersall Avenue which will run by early next year.

Speaking at a media visit to the worksite on Thursday morning, Environment and Water Resources Minister Masagos Zulkifli said the project will alleviate flooding along Orchard Road during heavy rain.

"The Stamford Detention Tank project that you see over here is both to mitigate and help out with possible flooding in the Orchard Road area. But more importantly in the longer term, we hope that we also help to mitigate the variable weather pattern that we're going to see. More frequent, intense rainfall in between," he said.

Flooding on Orchard Road occurs when the Stamford Canal overflows with rainwater.

The new 2-kilometre-long Stamford Diversion Canal will channel water from the upstream section of Stamford Canal to the Singapore River. It will run from Tanglin Road, along Grange Road and past Hoot Kiam Road, Irwell Bank Road and River Valley Road.

The diversion canal aims to reduce the load on Stamford Canal during heavy rain by about 30 per cent.

A detention tank is also being built on Tyersall Avenue, to reduce pressure on the new diversion canal in the event of heavy rainfall.

Excess stormwater in Holland Road drains will overflow into the tank for temporary storage, and will be released again into the diversion canal only when the water level in drains fall. Rainwater collected through the diversion canal will eventually flow from the Singapore River into Marina Reservoir.

The Stamford Detention Tank will be completed by early next year, and the diversion canal by early 2018.

To further protect buildings in Orchard Road from potential floods, PUB is also working with developers to invest in flood protection features like flood barriers, as well as crest and platform levels.

On top of flood prevention measures, the PUB has also completed drainage projects at 256 locations since 2013. These include drainage works at Cashew Road and Alexandra Canal.

- CNA/cy

Slight delay to Orchard Road flood mitigation works

SINGAPORE — Works to better protect Orchard Road from floods, which include a new Stamford Detention Tank and Stamford Diversion Canal, will be completed only in the first quarters of 2017 and 2018 respectively, a few months later than originally announced.

The anti-flood measures were introduced after the popular shopping belt was hit by a series a flash floods between 2010 and 2012. Flooding occurs when the Stamford Canal, the main drainage artery in Orchard Road, overflows with rainwater.

The detention tank, which will temporarily hold stormwater from existing drains along Holland Road, was originally slated to be completed by this year. The diversion canal, which will divert stormwater in the upstream section of the Stamford Canal catchment towards the Singapore River and eventually into the Marina Reservoir, was supposed to be completed by next year.

Commenting on the delay during a visit to the construction site yesterday, Environment and Water Resources Minister Masagos Zulkifli said soil conditions were “variable and challenging”, and changes had to be made to the original schedule to ensure the works would not disrupt traffic or pedestrians.

Describing the projects as “complex”, national water agency PUB said hard rock encountered during the tank’s construction required more time and effort to break it down.

Works for the diversion canal are also being carried out in densely built-up areas and require “detailed investigation” to ensure services such as cables and pipes would not be affected by tunnelling. When completed, the detention tank and diversion canal will ease the rainfall load on Stamford Canal by 30 per cent, PUB said in a progress update briefing yesterday.

The S$158 million, 2km diversion canal, stretching from Tanglin Road to Grange Road and off Kim Seng Road, will divert stormwater in the upstream section of the Stamford Canal catchment — about one-third of the entire 630ha catchment area — away from the Stamford Canal.

The stormwater will instead flow down the diversion canal towards the Singapore River, and eventually into the Marina Reservoir.

The first phase of the diversion canal construction in Tanglin and Kim Seng areas, involving the construction of covered box drains, is about 60 per cent complete.

Tunnelling works for a 1km stretch beneath Grange Road for the second phase of construction will begin next month. Construction of the S$69 million detention tank is also underway beneath Singapore Botanical Gardens’ coach park, where excess rainwater in drains along Holland Road will overflow into a chamber with two pipes to channel the water into the tank using gravity.

When sensors detect that water levels in drains have subsided, the tank will automatically release water back into the Holland Road drains and flow into the diversion canal.

Besides improving flood protection for Orchard Road, the two projects also serve to mitigate the effects of more variable weather patterns due to climate change, such as more frequent intense rainfall, said Mr Masagos.

Asked about the flood risk during the monsoon period, he said there is “more risk now than ever”, and Singapore is particularly vulnerable with many built-up and concreted areas.

“So, we have to mitigate that (flood risk) and make sure that in the event that heavy intense rainfall happens … we have enough measures where we can detain the water before it flows into the river or canals, as well as widening our canals and drains so that it can take up the volume,” he added.

Orchard's anti-flood works 50 per cent complete
Jalelah Abu Baker, Straits Times AsiaOne 10 Jun 16;

Major works by PUB to improve flood protection along Orchard Road are about halfway done, the national water agency said yesterday.

The Stamford Diversion Canal and Stamford Detention Tank will reduce the load of the Stamford Canal - which flanks Orchard Road on both sides - by 30 per cent, a spokesman said.

The diversion canal, which will relieve the Stamford Canal of a portion of water, is close to 50 per cent completed.

The detention tank, which will hold water temporarily so that less flows into Stamford Canal during heavy rainis more than 50 per cent completed.

The 2km diversion canal will divert rain water from 240ha of the total 630ha of catchment into the Singapore River through two underground tunnels and drains 6m to 14m wide, said Ridzuan Ismail, PUB's director of the Catchment and Waterways Department.

He was speaking at a media briefing at the Environment Building in Scotts Road.

The diversion canal is expected to be completed by the first quarter in 2018. It will stretch from Tanglin Road to Grange Road and off Kim Seng Road.

For 1 km of the stretch, works for two tunnels under Grange Road - measuring 4.5m in internal diameter - will start next month.

Stamford Canal, which stretches 4.7km under the Orchard Road shopping belt which includes malls such as Ion, Wisma Atria and Lucky Plaza, could not cope with heavy rain in several instances in 2010 and 2011, leading to floods in the area.

"Through these projects, the flood risk for the main Orchard Road area will be reduced, because we are diverting the flows from the upstream areas," Mr Ridzuan said.

He also pointed to data covering 35 years that shows that rainfall has become more intense, and heavy rainfall is more frequent.

The detention tank, the second in Singapore after one in Opera estate, can store as much water as that of 15 Olympic size pools, or 38,000 cubic metres.

It will sit 28m under the Singapore Botanic Gardens coach park.

Water flowing towards Stamford Canal from Holland Road will overflow from a drain along the road into a chamber where two pipes measuring 2.5m in diameter internally will channel the water into the tank.

Water sensors will alert the automated system to release the collected water when rainfall has subsided. The water will flow both ways by gravity.

Minister for the Environment and Water Resources Masagos Zulkifli visited the construction site of the tank yesterday.

The tank is expected to be ready by the first quarter of next year.

Mr Masagos said that by law, developers now have to include detention tanks in buildings over 0.2 ha, and that more than 30 buildings are now equipped.

PUB attributed a slight delay in the completion of the detention tank to a hard rock that needed time to break down.

As for the delay in the diversion canal, a spokesman said:"We did a detailed investigation of the services, for example, cables and pipes alignment to ensure that the tunnelling depth will not affect the services above."

In an update on the drainage improvement programme, Mr Ridzuan said that projects at 256 locations have been completed since 2013, 92 are ongoing, and 24 more are planned to start this year.