The Highways Department has begun to construct silt catch pits all along the four major arterial roads in the city.
The 1 foot by 1 foot pits that are meant to filter rain water of mud and garbage, are coming up every 5 metre. Each pit costs ₹18,000 to construct, and takes about a day to complete.
Officials in the department said that a grating is placed at the top of the silt catch pits, which are then connected to the storm water drains (SWD). “If we remove the grating, we can remove the silt.”
The work to construct the pits have been taken up following the suggestions of the Thiruppugazh Committee on flooding. The grating and the pit are supposed to greatly help reduce mud being carried by the rain water into the drains. Silt and garbage end up choking the drains and preventing free flow of water.
The pits are coming up along the 30 km length of Grand Southern Trunk Road (Anna Salai), 9 km of Poonamallee High Road, 11 km of Inner Ring Road, and 3 km of Walltax Road. The Greater Chennai Corporation has already constructed such silt catch pits.
A retired engineer, however, questioned the efficiency of the silt catch pits, especially during heavy rains. The water will be flowing very fast and naturally carrying what it can. “For the quantum of rain water that we witness, even the capacity of existing drains is not enough . In such a case 1 ft x 1 ft catch pits would only end up preventing water flow into the pits, he said adding that many modern techniques are available to prevent silting.
