Grace Chua Straits Times 11 Jun 11;
NATIONAL water agency PUB is going to give the prime Orchard Road area special protection to guard against flooding.
This means widening and deepening drains at the junction of Cuscaden and Tomlinson roads, possibly building a retention pond and even diverting water to other catchment areas.
But the various ideas tossed up to keep Orchard Road flood-free may prove costly, and that is something PUB must weigh.
Mr Tan Nguan Sen, PUB's director of catchment and waterways, told The Straits Times that the drains there - planned to meet the needs of a fully built-up Orchard Road - were operating at close to full capacity, given all the development in the shopping belt.
'Even though retention ponds and all that may work, we have to weigh the costs and benefits. Is it justifiable to spend those millions of dollars just to give the added protection?' he said.
Earlier, the idea of retention ponds had been floated by PUB and other experts as one way to catch some of the peak rainwater flows. Another suggestion was to construct a diversion canal to the Singapore River.
The cost of damage from flooding on Sunday and last year has not yet been tallied, but it was previously reported that property and vehicle damage claims from floods last June were estimated at about $8 million.
Since then, the agency has spent $26 million raising a 1.4km stretch of Orchard Road from Orange Grove Road to Cairnhill Road, to help alleviate flooding in the area.
If not for this exercise, Sunday's flood could have been worse, it said.
PUB also clarified that the flood that submerged parts of Tanglin Mall and St Regis Residences was not due to Stamford Canal overflowing - the cause of last year's flood - but a smaller drain in Grange Road that had overflowed.
It maintained that unusual rainfall intensity was the reason the drains and canals were overwhelmed on both occasions.
Besides expanding the capacity of the drains at the junction of Cuscaden and Tomlinson roads, it has built a wall in front of the Grange Road drain to prevent water from spilling out. By tomorrow, the drain will also be covered.
The National Environment Agency (NEA) said Sunday morning's rain intensity - 65mm in 30 minutes - has not been recorded over this part of Singapore for the last 15 years. 'The rainfall in Singapore varies significantly from year to year,' an NEA spokesman added. 'Based on our long-term records, our analysis of the rainfall patterns in Singapore shows no significant trend in the annual rainfall.'
There were no floods in Orchard Road for 25 years prior to last year, PUB said.
Last June, the weather station at the TripleOne Somerset building recorded a peak rainfall intensity of 85mm in an hour.
Since 1995, there have been two occasions when the year's highest rainfall intensity per hour at that station was greater than that of last June: in November 2007 and September 2008.
PUB did not give its specific planning parameters for the Orchard Road area.
However, it said that drains were designed based on the premise that nearly all the surrounding area would eventually be built up, which increases surface run-off when it rains.
Asked if it could show that more buildings did not contribute to the flooding, Mr Tan pointed out that the catchment area upstream of Stamford Canal, which includes Dempsey Road and the Botanic Gardens, had not been built up significantly in recent years.
Mall builds walls to fight floods
Wayne Chan Channel NewsAsia 10 Jun 11;
SINGAPORE: At least one building affected by the recent Orchard Road floods has already taken concrete measures to keep the water out.
Tanglin Mall, which suffered extensive damage during last Sunday's floods, is not taking any chances.
One day after the floods, the mall started building brick and concrete walls on its premises to protect key areas that contain important installations like electrical and telephone lines.
About 70 such walls - starting from the first level, going down to its four levels of basement - will be up by Saturday.
The walls are meant to stop the flow of water into the basement carpark during a flood. When the water reaches toe-level, sandbags will be laid out to further stem the flow.
Another way to keep the water out is to build humps, a recommendation made by the PUB. But an expert said these may not suit buildings along Orchard Road.
NTU Associate Professor Tan Soon Keat said: "(The humps) may not match the landscaping or the architectural outlook of the buildings....but (they can serve) as a quick measure to keep the water out of the buildings, particularly if the potential of flooding is imminent."
And if humps are to be built, they must be low enough for cars to drive over them.
He said the humps should be between 0.2 metre and 0.3 metre for cars to "comfortably" drive over, said Associate Professor Tan, who is from the Nanyang Technological University (NTU) School of Civil & Environmental Engineering.
Even then, he added, the humps may not be able to keep severe floods out.
"But at least it can buy some time for people to know that water is building up," he said.
-CNA/ir
Tanglin Mall readies for future floods
Wayne Chan Today Online 11 Jun 11;
SINGAPORE - They may hope for a green space and an underground water storage tank in Orchard to prevent floods like the one that washed in on Sunday, but for now, the management of one of the buildings badly hit by the flood is going ahead with a few measures of its own.
Cuscaden Properties, which owns and manages Tanglin Mall, has begun building brick and concrete walls to stop water from flowing into car park entrances and key areas containing electrical and telephone lines, even before PUB officers have come in to advise them on how to do so.
The work to build nearly 70 walls with a height of 60cm and 86cm, from the ground floor down to four basement levels, should finish by today. Sandbags have also been filled and will be deployed the next time it floods.
The mall's management had swung into action on Monday, said Tanglin Mall centre director Jenny Ng, 56, because "the weather is unpredictable and worse storms had been forecast".
She added, "Our intention was to first protect our mechanical, electrical and other critical equipment."
Other solutions that were discussed when PUB met the Orchard Road Business Association on Thursday included raised crests and road humps for the buildings affected by the recent flood. But these humps must not be too high - between 0.2m and 0.3m - so that a car can "comfortably" go over them, an expert told MediaCorp yesterday.
Even so, the humps may not be able to keep severe floods out, noted Associate Professor Tan Soon Keat.
"But at least it can buy some time for people to know that water is building up," he said.
Roads leading to lower ground may need higher humps and this may affect the overall look of their properties in Orchard Road, said Assoc Prof Tan, who is from the Nanyang Technological University's School of Civil and Environmental Engineering.
"These immediate measures may not match the landscaping or the architectural outlook of the building for the time being but as a quick measure to keep water out of the building, particularly if the potential of flooding is imminent, then I think this is a quick way," he said.
As for the underground water storage tank suggested by ORBA, PUB had said on Thursday it would study the proposal.
Meanwhile, PUB said it has installed about 1,600m of railings at 14 locations as of yesterday, following the death of a teenager last week who drowned after falling into a drain swollen with rainwater during a heavy downpour.
PUB to study underground tank proposal to curb flooding in Orchard
Hetty Musfirah Abdul Khamid Today Online 10 Jun 11;
SINGAPORE - National water agency PUB said yesterday it will study the Orchard Road Business Association's (ORBA) proposal of an underground tank to prevent floods hitting the shopping belt.
But as an immediate step, it will work with affected building owners to boost their flood prevention measures.
The meeting between PUB and the association yesterday took place at Traders Hotel, which is located in an area near Orchard Road, which was affected by the floods last Sunday.
MediaCorp was not allowed to film the session but it is understood that about 50 people including representatives from the PUB, the Singapore Tourism Board and the affected shopping malls turned up for the meeting.
The ORBA has said that it was disappointed with the PUB and wants long-term solutions to tackle the flooding.
The PUB described the meeting as "very useful" and that many ideas were exchanged during the session.
The agency is studying the idea of building a diversion canal from Stamford Canal to ease flood woes along the shopping belt.
The ORBA's proposal for an empty plot of land in the precinct to be used as a green space - with an underground tank to hold excess rainwater, was also discussed, and the PUB will be looking into suggestions to place water "holding tanks" in the basements of buildings.
Said PUB's director of its 3P Network Department, Mr George Madhavan: "We have been thinking of using retention ponds so it's an idea that we will take back and study very carefully. Basically, we want to find an optimal solution to improving flood protection on Orchard Road."
For now, PUB will lend its expertise to six building owners including Tanglin Mall and St Regis Residences, which were badly hit by Sunday's floods, to build "crests" - road humps that will prevent water from flowing into carparks.
The PUB said a suggestion by the ORBA to build a green space like New York's Bryant Park is also a good idea.
If approved, the space will have an underground water tank that absorbs and stores excess water while doubling up as a venue for outdoor events.
The proposed site is a 20,000 sq m piece of state land behind Ngee Ann City.
The ORBA said that the meeting was cordial and that the PUB was forthcoming in its explanations, but a lot of questions could not be answered, as they concerned long-term issues.
"We still want to know what is PUB's long term plan to address the flood problem because it seems like no one can guarantee that the flood will not happen again," said the ORBA executive director Steven Goh.
The ORBA will continue to pursue its proposals. "Perhaps it is beyond PUB and their issue involves planning, involves land issue and so on and so forth.
"So I think it is a multi-agency effort and as the ORBA we will work with the Singapore Tourism Board as our key partner to address some of our wish list and wants with them," said Mr Goh.
Recent floods prompt Liat Towers to install second set of floodgates
Sara Grosse and Liang Kaixin Today Online 14 Jun 11;
SINGAPORE - The management of Liat Towers plans to install another set of floodgates as the first set installed after last year's floods did not spare the building in Orchard Road during the recent downpour on June 5.
About 100mm of rainwater flowed into its basement stores.
A video taken by the contractor in charge of the flood barriers that morning showed that while the floodgates did work, the water flowed in through a gap between the barriers and the shops.
Liat Towers now plans to install six floodgates outside its basement stores at a total cost of about S$60,000.
Other buildings in Orchard, including Tanglin Mall, Orchard Towers, Lucky Plaza, The Regent and Palais Renaissance, are in talks with the contractor, Parafoil Design and Engineering, to see if they need floodgates as well, which will take about four to six weeks to complete.
Mr Jwee Quek, the product manager of Parafoil Design and Engineering, also suggested that the Public Utilities Board (PUB) address the problem of drainage outside Liat Towers, which he said is too small and easily blocked by leaves.
Hence, drains at the stairway were not able to drain the water fast enough, he explained. SARA GROSSE AND LIANG KAIXIN
