CHENNAI : Piggybacking’ technique will help the size of Chennai’s landfill spread shrink by half, according to officials in the Chennai Corporation. Currently, the Perungudi and Kodungaiyur landfills occupy more than 500 acres of land in the city. This technique reclaims existing landfills by allowing a new landfill to be constructed on the slopes of the existing landfill. A two-fold lining system is introduced to prevent landfill juices from seeping into the soil and entering groundwater levels.
According to a top Corporation official, the landfill mound which will be created, will free up space in the extremities and allow a new layer of waste to be deposited. “This time the leachate will be monitored in real time and collected between the two lining layers, and be disposed of carefully,” he said. According to the consultants who have prepared a feasibility report for this `500 crore project, the two lining layers will be made from a polyester mix and clay respectively.
This will ensure the leachate doesn’t stagnate or seep into groundwater levels. However, piggybacking landfill mounds over 40 feet have been found problematic. According to an article published in the Waste 360 magazine, there are often spaces in between the layers of garbage and the mound doesn’t solidify. With garbage mounds already towering over 25 feet in Kodungaiyur and Perungudi, the Corporation might find it hard to build the green mound that it has envisioned. But, a representative of the consultant said, the waste to energy system, which has been proposed for the landfills, will help reduce the quantum of garbage by incinerating some of the waste.
‘Piggybacking’ technique was attempted in a landfill in Pune in 2002. Experts have had mixed opinions about the outcome, but Corporation officials claimed it is the best option available. The United States Environmental Protection Agency mandates reclamation of landfills after closure, and Piggybacking is often used to fulfil this condition. The state government, to whom the Chennai Corporation has sent the feasibility report, is expected to take a call in the next two months.