A German technology using a polymer-based infiltration system has proved to be effective in reducing flooding and water stagnation and replenishing the groundwater. The system, a successful experiment conducted by the Greater Chennai Corporation, is currently in use at Besant Nagar. According to R.R. Sivaraam, rainwater harvesting consultant, the infiltration system is a sustainable solution for recharging groundwater that minimises the impact of urban development on the hydrological system.
By using filters and eco-blocks, the system is able to filter the silt in rainwater and replenish groundwater. During heavy rain, excess water is discharged to a nearby waterbody or the ocean. “We first saw the success of this system near the Vadapalani temple tank and are excited about its prospects here as well,” Corporation Commissioner Gagandeep Singh Bedi said.
In Beasant Nagar, a stormwater drain inlet with an infiltrating structure has been constructed at 30 m intervals in the existing drain network. A longer tunnel has been constructed at the end of the drain.
“Being a sandy stretch, water can stagnate, and instead of letting it flow directly to the ocean, we wanted to take steps to preserve the groundwater,” the Commissioner said. The inlet consists of fine and coarse filters as well as eco-blocks and geofabric filters. Eco-blocks are environmentally friendly bricks that are made from recycled materials.
“Eco-blocks are easily portable and have a life upwards of 50 years,” Mr. Sivaraam said, and added that installing the system required less manpower and took significantly less time. A major advantage of the infiltration system is that it prevents the mixing of sewage and rainwater.
Mr. Bedi acknowledged the usefulness of the system and said other sandy stretches could benefit from it too. The cost-effectiveness of the system will be determined through wider studies and consultations but its success has been recognised. He commented that introducing systems that recharged groundwater is being planned for the Kosasthalaiyar project.