‘Rampant sand dredging has harmful environmental, health effects’
KUALA LUMPUR: Rampant sand dredging along Sungai Perak can lead to disastrous environmental and health effects.
The sudden increase in sand mining on both sides of the second-longest river in Peninsular Malaysia has raised questions among environmental observers.
Among the concerns were the proximity of some of the dredging stations to intake points for water treatment plants that supply half the population in Manjung district.
The sand mining had, on several occasions, forced the closure of treatment plants because their pumps were clogged.
“The state water authority had raised the issue with the state action committee and we hope something is done about this,” a source said.
“During the district-level meeting, the Department of Environment and the Lands and Mines Department issued a statement that they would not approve new licences or renew existing ones for sand mining in Bota,” the source added.
Water expert Dr Zaki Zainudin said river sand mining would cause harmful substances, which had settled on the riverbed, to resurface and contaminate the water.
“Sand contains organic elements such as nitrogen, phosphorus, or heavy metal elements, such as iron, manganese or arsenic.
“When sand is dredged, these substances will resurface. This is not good, especially in large volumes.
“These harmful substances could seep into the source water if the sand mining is done upstream, or near water intakes,” said the water quality and modelling specialist.
Zaki said sand mining would increase the level of suspended solids in the river, causing it to turn murky, which was often referred to as the “teh susu” phenomena.
He added that excessive amounts of suspended solids in the river would disrupt the operations of water intake plants.
“This will force the authorities to use more coagulants, such as aluminium, to treat the water before it can be supplied to consumers.
“Organisms could react with (the extra) chlorine used during the disinfection pro- cess and produce tri- halomethanes, such as chloroform, which can be hazardous to consumers.
“Heavy metals cannot be removed by conventional water treatment processes. These constituents would lead to health implications,” he said, adding that the negative impact from sand mining would be exacerbated during the dry season.
He added that suspended solids would destroy the breeding ground of river life and force migration.
“Fish and aquatic species indigenous to downstream reaches would be forced to migrate elsewhere. In serious cases, certain aquatic species, particularly the more sensitive ones, may face extinction.
“If there are aquaculture activities downstream, they too would be affected by suspended solids stirred up by the dredging.”
Sahabat Alam Malaysia field officer Meor Razak Meor Abdul Rahman said the non-governmental organisation had received reports from land owners who complained that they had lost their land to sand mining.
“Sand mining causes serious river bank erosion. It results in the river becoming wider and shallower.
“We have received complaints from land owners who claimed that their land is no longer accessible because of erosion, aggravated by sand mining.”
Sand extraction, Meor said, was also threatening river terrapin landing points in the state.
“River terrapins are considered critically endangered. Instead of helping to ensure the survival of the species, we are allowing sand mining to destroy their landing points.
“We hope the state government will not approve any sand mining within 2km of the River Terrapin Conservation Centre in Bota Kanan.”