‘Risky to build on ex-mangrove swamp land’


BALIK PULAU: A mangrove ecologist has warned of the risk of development encroaching into mangrove swamps, and the risks are for people and buildings.

Dr Foong Swee Yeok predicted that the road or planned property development on the eastern coastline of Penang island would not endanger the swamp or wildlife.

But she said the future road and buildings might suffer because the land on Balik Pulau’s coastline is all ex-mangrove swamp land, and there could be as deep as 25m of mud and clay down below.

“Developers will know how to pile deeply until they reach the bedrock for high rises, but there is no piling requirement for two-storey homes.

“You see nothing wrong in the first 10 years or so, but after that, things start sinking.

“Roads become wavy, uneven and start breaking apart,” she warned.

Dr Foong, who has been studying mangrove swamps since 1996, explained that the thick column of peat, mud and clay below the swamp is high in organic matter and once disturbed, it is prone to shifting over a long period after development.

“Waterlogged and anaerobic peat in the swamp becomes aerobic when drained. Then you get biological oxidation or mineralisation of the organic deposits. That is why the soil will sink,” she pointed out.

She said in developed ex-mangrove swamps on the island, such as parts of Bayan Lepas and Batu Maung, there have been numerous instances of buildings sinking and cracking after a few decades and this was due to the slow shifting of the mud and clay below.

Dr Foong also urged authorities to look into the operations of over 40 shrimp or fish dugout ponds fronting the land which a developer from Kuala Lumpur plans to build 276 terraced houses, 214 semi-detached houses, 91 double-storey bungalows, two 16-storey blocks of condominiums, two 16-storey blocks of low-cost flats, two blocks of retail shoplots, a school, mosque, community hall and other public amenities.

She said the tens of tonnes of shrimp and fish reared in the ponds produced vast amounts of nitrate and ammonia pollution.


   

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