Channel NewsAsia 30 Nov 11;
SINGAPORE: With more wet weather expected in the coming weeks, buildings will be better protected from flash floods with new drainage measures that take effect from December 1.
The minimum height of platform, land reclamation and crest levels for new developments will be raised to provide better flood protection for buildings.
The design parameters for new drains will also be enhanced to cater to more intense rain storms.
These measures are covered under a revised Code of Practice on Surface Water Drainage of national water agency, PUB.
The revisions are part of recommendations made by an Inter-Agency Drainage Review Committee (IADRC) which was formed in August 2010 to review drainage design requirements for flood control.
Their recommendations were later refined after consultations with the public and professional bodies from May to August 2011, and incorporated into the sixth edition of the code to provide stronger safeguards against flash floods.
For general developments, minimum platform levels have to be at least 30cm above the adjacent ground level or 60cm above the highest recorded flood level (if any), whichever is higher.
For commercial/multi-unit residential developments with basements such as shopping centres, office buildings and condominiums, the minimum platform levels have to be at least 60cm above the adjacent ground level or 60cm above the highest recorded flood level (if any), whichever is higher.
If these levels cannot be met due to site constraints, building owners can propose alternative design approaches for flood protection.
To cater for rising sea levels in the future, the minimum reclamation levels have been increased to 104.0mRL along the southern coast and 104.5mRL along the northern coast, approximately one metre higher than the current standards.
Design standards for new drains will be raised.
Depending on the size of the catchment, this can vary from an increase of 15 per cent to 50 per cent in drainage capacities.
PUB's deputy director for catchment and waterways, Mr Lim Meng Check, said: "We are seeing an increase in maximum rainfall intensities in Singapore over the past 30 years. Under the revised Code of Practice, we have increased our design standards to ensure that our drainage system is robust enough to cope with the higher intensity of rain. Over and above this, we have also raised the drainage requirements for developments to provide additional flood protection for buildings and key infrastructure."
To ensure that the surface run-off from developments under construction does not affect adjacent developments, developers have to ensure that the site can cope with more intense rain.
The required storage capacity for sedimentation basins or storage ponds/tanks at construction sites has been increased.
- CNA/fa
New PUB design standards for flood protection
Business Times 1 Dec 11;
NATIONAL water agency PUB has announced a revised code of practice on surface water drainage which provides greater flood protection for Singapore.
Taking effect today, the stipulated minimum height of platform, land reclamation and crest levels for new developments will be raised to provide better flood protection for buildings. The design parameters for new drains will also be enhanced to cater for more intense rainstorms.
These revisions follow recommendations made by an Inter-Agency Drainage Review Committee (IADRC) which was formed in August 2010.
For general developments, platform levels have to be at least 30cm above the adjacent ground level or 60cm above the highest recorded flood level (if any), whichever is higher, PUB said.
For commercial/multi- unit residential developments with basements such as shopping centres, office buildings and condominiums, the platform levels have to be at least 60cm above the adjacent ground level or 60cm above the highest recorded flood level (if any), whichever is higher. If these levels cannot be met due to site constraints, building owners have the option of proposing an alternative design approach for flood protection.
To cater for rising sea levels in the future, the minimum reclamation levels have been raised approximately one metre more than the current standards. In addition, design standards for new drains will be raised to cater for more intense rainstorms.
Said Lim Meng Check, PUB's deputy director for catchment and waterways: 'We have increased our design standards to ensure that our drainage system is robust enough to cope with the higher intensity of rain. Over and above this, we have also raised the drainage requirements for developments to provide additional flood protection for buildings and key infrastructure.'
Singapore has been hit by flash floods in recent months, affecting low-lying areas including the Orchard Road shopping belt.
Drainage code updated to focus on floods
PUB's revised rules apply to new buildings, those to be redeveloped
Daryl Chin Straits Times 1 Dec 11;
NATIONAL water agency PUB yesterday announced details of an updated drainage code which new buildings have to abide by to better prepare for floods.
The changes include making the minimum height of platforms higher and increasing drainage capacities.
But the revised rules, which are mandatory, will apply only to new buildings and existing buildings slated for redevelopment.
These changes are a result of recommendations made by an inter-agency drainage review committee, as well as input from public and professional bodies.
The committee was formed in August last year to review drainage requirements for flood control after heavy rain caused massive flooding in Orchard Road in June the same year.
As part of the changes, buildings with basements, such as shopping malls and condominiums, need to have a minimum platform level of at least 60cm above ground level.
Before the changes, the minimum platform level could be at ground level.
In anticipation of more intense storms, drainage design standards have also been updated under the revised code.
Depending on the size of the catchment to store rainwater, these larger drains can vary up to a 50 per cent increase in drainage capacity.
Mr Lim Meng Check, PUB deputy director for catchment and waterways, said Singapore has experienced an increase in maximum rainfall intensities over the past 30 years.
'Under the revised code of practice, we have increased our design standards to ensure that our drainage system is robust enough to cope with the higher intensity of rain,' he said.
'We have also raised the drainage requirements for developments to provide additional flood protection for buildings and key infrastructure.'
Associate Professor Susanto Teng of Nanyang Technological University's School of Civil and Environmental Engineering said such measures are timely, given the higher occurrence of flash floods.
In 2009, flash floods occurred only on six days, according to the PUB. The figure went up to 13 last year, and has hit 12 so far this year.
'Essentially, I think new buildings will be on a par with those built in flood- prone areas in the United States, so it's a welcome move,' said Prof Teng.
He said existing building owners should also look at their current anti- flood measures and decide if these are sufficient to combat intense rainfall.
'It's a tough issue as it involves costs and construction difficulties, particularly in built-up areas like Orchard Road. But if building owners don't do anything, tenants will move out if things get out of hand,' he said.
Dr Ho Nyok Yong, president of the Singapore Contractors Association, pointed out that steps must be taken to improve the overall infrastructure.
'The updated measures will definitely help new building owners when floods happen. But once you raise the floor, the water still has to run somewhere,' said Dr Ho, who is also the director of engineering firm Samwoh Corporation.
'That means the surrounding vicinity of the building also has to have an adequate drainage system.'
