Alert system overwhelmed by storm

Water level surged from 50% to overflowing in less than two minutes
Grace Chua Straits Times 8 Jun 11;

IN A matter of minutes during Sunday's heavy storm, Stamford Canal at Orchard Road was overwhelmed.

So was the PUB's water level sensor software, which sends out SMS flood alerts to building owners in flood-prone areas.

The software was programmed to send out alerts when water levels in canals hit 75 per cent, indicating a 'moderate' risk of flooding; then at 90 to 99 per cent, indicating a 'high' risk. It was not programmed to send out text alerts if the water level went beyond 100 per cent.

However, at the Stamford Canal in front of Forum The Shopping Mall that day, water levels surged from 50 per cent to overflowing - or above 100 per cent - in two minutes or less.

The result? The building managements of Tanglin Mall and St Regis Residences and Hotel did not receive any alerts. Both the mall and St Regis Residences suffered serious flooding, although the hotel was spared that.

PUB explained what happened yesterday, a day after it had revealed that it sent flood alerts to building owners except those from Tanglin Mall and the St Regis complex.

The national water agency said the software glitch has since been fixed.

It has been re-programmed so that SMS alerts will be sent out once a canal is completely filled; that is, when water levels hit 100 per cent and above.

PUB said that the earlier system had assumed that alerts would have been sent at the 75 per cent and 90 per cent marks, making another alert redundant.

However, on Sunday, water levels at that segment of Stamford Canal rose 'three or four times faster than anything we have seen before', said Mr Peng Kah Poh, director of PUB's infocommunnications department.

'It was so high that it bypassed the trigger points of 75 per cent and 90 per cent, so the SMS alert was not sent,' he said.

The PUB said that from next month, members of the public can also subscribe to the SMS service.

It will also look at shortening the current two-minute time interval for monitoring water levels during wet weather.

It will also review how often the sensors 'sample' water levels during thunderstorms, as well as where additional sensors should be.

The PUB started installing water-level sensors in several major drains and canals from 2007. After the big floods in June last year, more were installed, and water-level information was also made available to the public on its website.

By the end of last year, there were 90 such sensors in waterways like Stamford Canal, which runs under Orchard Road.

There are now 93 water sensors, and this will be increased to 150 by the end of this year, including in the drains leading to the Stamford Canal near the junction of Napier and Grange roads.

In a separate trial, the PUB is also monitoring flooding and water levels through CCTV cameras along Bukit Timah Road, and said it will soon decide whether to roll this scheme out elsewhere.

SMS alerts are currently sent to 117 schools, and condominium and building managers, in flood-affected areas that have subscribed to them.

Building managers and shopowners in such areas said they would like to sign up for the alerts.

A spokesman for CapitaMalls Asia, which manages Ion Orchard and Plaza Singapura, said both buildings would be signing up, although Ion Orchard was not affected by the floods this year or last year, and also has building features to prevent water from getting into ground-floor entrances.

At Cluny Court in Bukit Timah, Ms Elisa Ding, director of manager Cluny Lease, said it had signed up for SMS alerts after it was badly flooded last year. It received alerts last year but not this year. The PUB clarified that this was because Cluny Court had put a larger hump across its basement to prevent water flowing in.

But even if building managers do receive alerts, there is sometimes hardly any time to react.

Mr Chik Hai Lam of Goldvein, which owns Liat Towers, remarked: 'They kept on giving me SMSes I have no time to read.'

But he said the SMSes were enough to prepare his team, which was on site early in the morning on Sunday.

Liat Towers was spared heavy flooding.

Additional reporting by Fiona Low, Yuen Sin & Neo Wen Tong

PUB may tweak building codes, drain design rules
Daryl Chin Straits Times 8 Jun 11;

FOLLOWING Sunday's flood which put the upper reaches of Orchard Road and other places under water, national water agency PUB is looking into tweaking the building codes.

Beyond tightening the requirements to further flood-proof buildings, it will also review the guidelines defining the design and construction of stormwater drains across the island and raising the level of freshly reclaimed land.

Details on the changes to building codes are still sketchy, but Minister for the Environment and Water Resources Vivian Balakrishnan had cited flood- proofing buildings as one area that his ministry, the PUB and the Building and Construction Authority need to look into.

Specialists in engineering, asked by The Straits Times to identify possible changes to the building codes, said the tweaks could come in the form of raising the ground level of buildings above flood levels, and enlarging their networks of underground drains.

Associate Professor Susanto Teng of the Nanyang Technological University's (NTU) School of Civil and Environmental Engineering said the PUB has its work cut out for it: It has to study current flood levels, find out the causes of the deluge and change building codes accordingly.

The PUB lists online a code of practice on the draining of surface water which all buildings must follow to the letter.

It states, for example, the minimum height of the platform on which a building must stand. This minimum level depends on where the building is and what it is used for.

Another building requirement states the maximum or crest level which flood water is allowed to reach - at least 75cm above the highest tide level in the area.

Buildings with basements are required to have water pumps of sufficient size and must install separate holding tanks for rainwater that is collected, and water that is to be pumped out.

If a building breaches the code, PUB can, under the Sewerage and Drainage Act, issue a notice to direct building owners to fix the fault.

The agency would only say that 'a few' such notices have been issued.

Associate Professor Tan Soon Keat, who is also from NTU's School of Civil and Environmental Engineering, suggested that the Government and building owners explore setting up larger stormwater catchment areas, either under roads or within buildings.

'But these are just possibilities, as more studies are needed. One thing is for sure: owners can no longer assume floods will not occur on their premises,' he said.

Mr Pek Lian Guan, executive director and chief executive of building construction and civil engineering contractor Tiong Seng Holdings, suggested that buildings be required to invest in bigger water pumps so they can better cope with sudden deluges of water.

Dr Ho Nyok Yong, director of engineering firm Samwoh Corporation, said changes to the building code were called for, but that the issue was a complicated one because of the rapid changes in land usage and increasing urbanisation.

He added: 'You can keep redirecting water, but it has to flow somewhere. It's good that the authorities are checking whether the existing drainage system is good enough to withstand heavy rains, but it must be properly planned to solve the issue once and for all.'

Mr Pek said that whatever provisions were made to change the way buildings are constructed would only be a 'second layer of defence'.

'The first line should come in the form of an updated overall drainage plan,' he said.

PUB improves SMS alert system for flood risks
Hetty Musfirah Abdul Khamid Channel NewsAsia 7 Jun 11;

SINGAPORE: National water agency PUB is improving its SMS alert system for flood risks.

In July, it will also make the SMS alert system available for the public to subscribe to.

And the system will also be made more sensitive to rising water levels.

The measures come after building owners at Orchard Road - specifically Tanglin Mall and St Regis - failed to receive SMS alerts about the floods on Sunday morning.

Currently the alert system is only made available to building owners in areas that are susceptible to floods.

Each subscriber receives alerts triggered from water sensors located along drains and canals.

Stamford Canal, which runs through Orchard Road, has seven water sensors.

When it rains, the sensors monitor water levels every two minutes - a shorter frequency compared to 10-minute intervals during dry weather conditions.

When water levels hit the 75% mark (which indicates moderate flood risk) or 90% mark (which indicates a high flood risk), the sensors will trigger off a process to send an SMS alert to subscribers.

The catch is that the system was not designed to trigger an SMS alert when water levels hit 100%. That was why Tanglin Mall and St Regis did not receive the SMS alerts on Sunday.

PUB says that due to the high intensity of rain on Sunday, the water levels had already hit 100% when the water sensor serving the two locations read the levels.

The particular water sensor is located at Stamford Canal near Forum Mall.

"For that particular day, what happened was that the rate of increase for the water was pretty high; it was so high that it bypassed the trigger points of 75% and 90% levels. So the SMS alert was not sent," said PUB's director for infocomm department, Peng Kah Poh.

PUB says it has already tweaked the system, such that it will start triggering SMS alerts if water levels hit 100%.

It will also look into shortening the two-minute time interval for monitoring water levels.

"We based the two minutes on past records. We have actually been monitoring these level sensors for the past two to three years, and what actually happened on that Sunday was that the rate of increase of water was at least three to four times....than the worst-case scenario," said Mr Peng.

The SMS alert system is also useful for PUB. It says that once it receives alerts that water levels have hit the 50% mark in certain sites, it will deploy contractors and staff to those places to check for blockage and monitor the situation. Gratings will also be opened to flush out flood waters where possible.

There are currently 93 water sensors along Singapore's drains and canals. These will be further increased to 150 by the end of this year.

PUB says it will install water sensors for the drains leading to the Stamford Canal near the junction of Napier Road and Grange Road.

It is also conducting a trial run of monitoring water levels through CCTV cameras like those along Bukit Timah Canal.

- CNA/ir http://www.blogger.com/img/blank.gif

PUB tweaks flood alert system

From next month, public can subscribe to SMS alerts, too
Hetty Musfirah Abdul Khamid Today Online 8 Jun 11;

SINGAPORE - The floods at Tanglin had risen so swiftly that it was well beyond the sensor mark that triggered alerts to warn subscribers of the impending flood - as the system was not designed to do so after water levels went past a certain point.

Hence, Tanglin Mall and St Regis did not receive the SMS alerts on Sunday, when the intense rain caused water to pour into the two buildings along Orchard Road, said the Public Utilities Board (PUB) yesterday, as it unveiled a raft of measures to improve the SMS alert system for impending floods.

Under the current alert system - only available to building owners in areas prone to flooding - subscribers receive alerts triggered by water sensors located along drains and canals.

When it rains, the sensors monitor water levels every two minutes, compared to 10-minute intervals during dry conditions.

When water levels hit the 75-per-cent mark (which indicates moderate flood risk) or 90 per cent mark (which indicates a high flood risk), the sensors send an SMS alert to subscribers. The PUB also checks sites where water levels hit the 50 per cent mark for blockages, and monitors the situation there.

However, the system was not designed to trigger an SMS alert when water levels reach 100 per cent - the level reached on Sunday according to a sensor reading at Stamford Canal near Forum mall.

"On that day, the rate of increase for the water was pretty high; it was so high that it bypassed the trigger points of 75 per cent and 90 per cent levels. So the SMS alert was not sent," said PUB infocomm department director Peng Kah Poh.

The PUB has tweaked the system so that it will start sending SMS alerts if the water levels rise beyond the 100 per cent mark.

From next month, members of the public can also subscribe to the alerts.

The PUB will also look into reducing the two-minute interval for monitoring water levels when it rains.

"We based the two minutes on past records. We have actually been monitoring these level sensors for the past two to three years, and what actually happened on that Sunday was that the rate of increase of water was easily about three to four times ... than the worst-case scenario," said Mr Peng.

The number of water sensors will also be increased to 150 by the end of this year, from the current 93.

The PUB said it will install water sensors at the drains leading to the Stamford Canal near the junction of Napier Road and Grange Road.

It is also conducting a trial run of monitoring water levels through CCTV cameras like those along Bukit Timah Canal.

Tessarina's S$90,000 investment that kept the flood waters at bay
Ong Dai Lin Today Online 8 Jun 11;

SINGAPORE - When the heavens opened on Sunday morning, Tessarina condominium resident, Dr Audrey Tan, was worried and yet filled with anticipation at the same time.

The building at Wilby Road, off Bukit Timah Road, had been flooded twice, and Dr Tan, the chairman of the condominium's flood committee, told MediaCorp: "Sunday was a real test since Wilby Road was raised ... Now we know that the raising of the road was very successful."

The Land Transport Authority (LTA) and the PUB had completed a three-month project in January to raise the road level by almost a metre in some areas. This was critical in preventing flooding outside Tessarina condo on Sunday, said Dr Tan.

The condominium was badly hit during the Bukit Timah floods in November 2009. After it was flooded again last July, a flood committee was set up to tackle the problem. By February, the residents had pooled S$90,000 to install six flood barriers at the exits and a closed-circuit television camera (CCTV) to monitor Bukit Timah Canal.

Environment and Water Resources Minister Vivian Balakrishnan went to the Tessarina yesterday evening to understand what worked for the condominium. Its management committee demonstrated how the flood barriers kept out the waters.

They also showed him their CCTV camera on the 10th storey, which monitors the canal. When the waters reach a certain level, a staff member will sound a siren to alert residents. This will let them know the flood barriers will be closed and they can then decide if they want to drive their cars from the basement car park to higher ground.

Dr Balakrishnan said: "So there are some measures which you can take at a local level as a final line of defence, while PUB works on the long-term solution, which is expanding downstream the drainage and making sure that any work that (LTA) does won't compromise the drainage from here and from the road into the canal."

Dr Tan said Member of Parliament for Holland-Bukit Timah Group Representation Constituency, Mr Christopher de Souza, had worked very hard with the authorities to get Wilby Road raised.

Mr de Souza, who noted that other parts of Bukit Timah Road also saw flash floods, said he would now look at how those residents could be helped. He said: "I share the anxiety of my residents who live along Bukit Timah Road ... and will make concerted efforts to help alleviate the flooding." ADDITIONAL REPORTING BY NG JING YNG