Sep 5, 2008 Friday

Backyard walls collapse in mudslide

Walls, fences of two homes off Jalan Kayu affected in midnight incident after heavy rain

By Chong Chee Kin & Yeo Ghim Lay

While residents believe that construction work behind their homes could have caused the walls to collapse, the project's engineer said the walls could be structurally weak. -- ST PHOTO: DESMOND LIM

RESIDENTS in a private housing estate off Jalan Kayu scrambled for help after a mudslide brought the walls and fences at the back of their homes down late on Wednesday night.

The mudslide that followed a heavy downpour that night left one occupant of a terrace house in Jalan Tari Serempi without the 2m-high wall and fence at the back and badly damaged the perimeter wall of another.

While the residents believe that the construction of a block of houses behind their homes could have something to do with the incident, the engineer and developer for the project pointed their fingers at the weak structure of the walls.

The Building and Construction Authority (BCA) has ordered construction works on the site to stop until further notice. An investigation is under way. A spokesman said the Qualified Person for structural works, or the project's engineer, has inspected the site and 'confirmed that the structural integrity of the houses had not been affected by the collapse'.

Madam Habsah Sultan, 50, a property agent who lives at 2, Jalan Tari Serempi, said there had been a lot of construction work going on since a month ago. 'With the digging and the rain, the soil might have just given way,' she said.

Her neighbour, Madam Toh Wong See, agreed, adding that in her 12 years in the neighbourhood, mudslides have never happened, not even during heavy rain.

Madam Habsah was awake when the walls collapsed around midnight.

She told The Straits Times: 'I was still up when I heard a loud sound like a thunderclap at about 11.50pm. I thought it was the storm again but when I went to the back of the house, I saw part of the backyard area had given way and the wall and perimeter fencing had buckled.'

Madam Toh, 57, a housewife who lives with her son, his wife and their two young children, was watching TV at that time and ran to the backyard to see what happened. Her walls did not collapse but there was a 1m crack on a side wall near where the earth had moved.

Both women woke up their families, alerted the neighbours and rang the police. 'Thankfully, no one was injured but who can be sure this would not repeat when it rains again?' Madam Habsah said.

Both families were adamant about staying put. 'The contractors and BCA officers came by this morning and told us the place is safe. But I just wish they would quickly repair the walls,' Madam Toh said in Mandarin yesterday.

Mr Liauw Chin Lee, the 48-year-old developer for the construction behind their houses, said that repairs are under way. 'It's too early to estimate what the repair costs are, but the walls will be up as soon as possible,' he said in Mandarin.

The authorities had told him that the walls should be up before any further construction could continue, he said.

Both Mr Liauw and the project's design engineer, Mr Chua Hock Beng, felt that the rain and the walls were to blame.

'The walls which had given way have been there a long time and weren't built very well,' Mr Chua said.

Even so, Mr Liauw said he would not argue about whose fault it was.

'I am going to live here when the construction is completed and these affected people will be my neighbours. Thankfully, no one was hurt. I'll just treat this as a costly expenditure to ward off misfortune.'

A geotechnical engineering expert told The Straits Times it appears that the wall could have collapsed after rainwater collected in the soil behind the wall, exerting pressure on it.

Professor Leung Chun Fai, from the department of civil engineering at the National University of Singapore, said: 'This can usually be avoided if 'weep holes' are constructed in walls to allow the water to pass through. The holes will then have to be cleared frequently because leaves and other objects might block them over time.'

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