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SINGAPORE: The cause of flooding at Liat Towers last Friday has been traced to Stamford Canal's fundamental problem of being unable to cope with the surge in water during heavy and prolonged rainfall.
And that's why during last Friday's downpour, the canal reached its full capacity very quickly.
Explaining on Friday why the flooding occurred on December 23, PUB said that the prolonged and heavy rain that day caused some parts of Stamford Canal to flow full.
The national water agency said that 152.8mm of rain fell on Orchard Road from 2.20pm to 5.20pm that day.
This is equivalent to about half the average monthly total of 287.4mm of rain recorded for the entire month of December over the last 142 years (1869 to 2010).
The sustained heavy downpour resulted in the flooding of several roads including the Thomson/Cambridge areas as well as the basements of Liat Towers and Lucky Plaza.
At Lucky Plaza, rainwater drained into the basement via the steps.
For Liat Towers, rainwater that had drained off from the roof and the back area of the building overflowed into the basement area from an internal drain, as water could not flow out into the canal, which was full.
The pumping system at Liat Towers is able to pump out the water from the open basement area when the canal is not full.
But when the Stamford Canal in front of Liat Towers reached 100 per cent capacity, the pumps were not able to discharge the water in the basement into the canal. However the pumps were still able to pump some water onto the pedestrian walkway.
To improve flood protection during similar storms, Liat Towers will be building a perimeter wall along its internal drain as an interim measure. Construction of the wall will begin on December 31 and will take about four to five days.
Liat Towers management is also considering installing more goose-neck pumps, perhaps even at a larger capacity, to divert water onto the pedestrian walkway if water overflows past the perimeter wall.
PUB said it takes its responsibility for flood management seriously. It added that while it is not possible for PUB to completely eliminate flash floods, it will do everything feasible to prevent it, mitigate it and keep the public informed.
The agency has been working closely with the management of flood-affected buildings.
PUB's director of 3P network, George Madhavan, said: "Since 23 December, PUB officers have been meeting regularly with the management of Liat Towers to review, to enhance the flood protection for this building.
"What we are clear is that both PUB as well as Liat Towers are determined to put in measures to make sure that this (flooding) does not recur."
Liat Towers' director of property management, Lydia Tjhia said: "PUB (officers) have come down many times for discussions with Liat Towers and they have been very helpful.
"They have given us a few recommendations, one of which is the raising of the 60cm curb. This will allow more water to be held within this so-called pond and with the difference in pressure we'd be able to drain the water into the canal.
"However, when the canal is full there may be times when the water might overflow onto the pedestrian walkway."
As for Lucky Plaza, its management is in the process of putting in place flood barriers after getting in-principle approval from the Urban Redevelopment Authority (URA) in October.
But the installation could be delayed.
Lucky Plaza has been asked to tweak its design of the barriers to ensure better pedestrian flow along the walkway.
URA said Lucky Plaza has yet to resubmit the refined proposal to URA for further consideration and approval.
PUB said it will work with Lucky Plaza to ensure that an effective flood prevention system is implemented quickly.
PUB noted that although the rainfall recorded on 23 December was higher than what was recorded in June last year, Orchard Road remained passable to traffic.
This was because after the June 2010 floods at Orchard Road, PUB raised the road to improve the flood protection for the area. This was completed in June this year.
Nevertheless, recognising the constraints in expanding Stamford Canal given the highly urbanised development in the area, PUB is studying the feasibility of building a detention pond and a diversion canal for the Stamford catchment in the longer term.
The study started in August this year. PUB will share the details when it completes the study by May 2012.
- CNA/fa/ir
And that's why during last Friday's downpour, the canal reached its full capacity very quickly.
Explaining on Friday why the flooding occurred on December 23, PUB said that the prolonged and heavy rain that day caused some parts of Stamford Canal to flow full.
The national water agency said that 152.8mm of rain fell on Orchard Road from 2.20pm to 5.20pm that day.
This is equivalent to about half the average monthly total of 287.4mm of rain recorded for the entire month of December over the last 142 years (1869 to 2010).
The sustained heavy downpour resulted in the flooding of several roads including the Thomson/Cambridge areas as well as the basements of Liat Towers and Lucky Plaza.
At Lucky Plaza, rainwater drained into the basement via the steps.
For Liat Towers, rainwater that had drained off from the roof and the back area of the building overflowed into the basement area from an internal drain, as water could not flow out into the canal, which was full.
The pumping system at Liat Towers is able to pump out the water from the open basement area when the canal is not full.
But when the Stamford Canal in front of Liat Towers reached 100 per cent capacity, the pumps were not able to discharge the water in the basement into the canal. However the pumps were still able to pump some water onto the pedestrian walkway.
To improve flood protection during similar storms, Liat Towers will be building a perimeter wall along its internal drain as an interim measure. Construction of the wall will begin on December 31 and will take about four to five days.
Liat Towers management is also considering installing more goose-neck pumps, perhaps even at a larger capacity, to divert water onto the pedestrian walkway if water overflows past the perimeter wall.
PUB said it takes its responsibility for flood management seriously. It added that while it is not possible for PUB to completely eliminate flash floods, it will do everything feasible to prevent it, mitigate it and keep the public informed.
The agency has been working closely with the management of flood-affected buildings.
PUB's director of 3P network, George Madhavan, said: "Since 23 December, PUB officers have been meeting regularly with the management of Liat Towers to review, to enhance the flood protection for this building.
"What we are clear is that both PUB as well as Liat Towers are determined to put in measures to make sure that this (flooding) does not recur."
Liat Towers' director of property management, Lydia Tjhia said: "PUB (officers) have come down many times for discussions with Liat Towers and they have been very helpful.
"They have given us a few recommendations, one of which is the raising of the 60cm curb. This will allow more water to be held within this so-called pond and with the difference in pressure we'd be able to drain the water into the canal.
"However, when the canal is full there may be times when the water might overflow onto the pedestrian walkway."
As for Lucky Plaza, its management is in the process of putting in place flood barriers after getting in-principle approval from the Urban Redevelopment Authority (URA) in October.
But the installation could be delayed.
Lucky Plaza has been asked to tweak its design of the barriers to ensure better pedestrian flow along the walkway.
URA said Lucky Plaza has yet to resubmit the refined proposal to URA for further consideration and approval.
PUB said it will work with Lucky Plaza to ensure that an effective flood prevention system is implemented quickly.
PUB noted that although the rainfall recorded on 23 December was higher than what was recorded in June last year, Orchard Road remained passable to traffic.
This was because after the June 2010 floods at Orchard Road, PUB raised the road to improve the flood protection for the area. This was completed in June this year.
Nevertheless, recognising the constraints in expanding Stamford Canal given the highly urbanised development in the area, PUB is studying the feasibility of building a detention pond and a diversion canal for the Stamford catchment in the longer term.
The study started in August this year. PUB will share the details when it completes the study by May 2012.
- CNA/fa/ir
:o
