Mumbai: BMC to erect boundary wall near Thane creek to prevent discharge of leachate from Deonar

TO PREVENT the discharge of hazardous leachate generated from Deonar dumping ground, the BMC will be erecting a boundary wall near Thane creek with the help of synthetic vinyl sheets. The wall is also meant to help the civic body in preventing the collapse of garbage mounds on the creek side, which flows adjacent to the dumping ground.

Leachate is a contaminated liquid generated from water percolating through a solid waste disposal site. It contaminates ground and surface water as it contains high concentration of hazardous organic chemicals like ammonia nitrogen and heavy metals.

“The synthetic sheet piling will stop percolation of leachate to the creek side and contamination. The separated leachate will be moved to some other location for further treatment. This will also help in the possibility of collapse of garbage mound either on creek side or on landfill area,” said Suresh Kakani, Additional Municipal Commissioner in the BMC.

In the past, environmental activists and authorities had warned the civic body about the discharge of leachate in Thane creek from the dumping ground. In 2018, National Green Tribunal (NGT) slapped a Rs 5-crore fine on the BMC for improper handling of waste, including failure in separating leachate at Deonar dumping ground. At present, the city generates over 5,400 metric tonnes of garbage daily, of which over 25 per cent is dumped in Deonar and the rest goes to Kanjurmarg.

According to officials from the solid waste management department, work will be taken up in two phases and, in the first phase, about 1 km area abutting the creek will be covered with synthetic sheet piling. After that, in the second phase, another 1 km will be taken up. The BMC plans to go 23 metres deeper from the ground level for the piling to prevent any percolation of leachate and collapse of garbage, which could be triggered due to fast moving creek streams.

The BMC is awaiting nod from Maharashtra Coastal Zone Management Authority (MCZMA) to construct synthetic sheets wall near Thane creek. “Since the project area is adjacent to the creek and comes under CRZ II (coastal regulation zone), the BMC will have to take permission from MCZMA. The contractor is responsible for seeking clearance from the authority,” said a senior official from the department.

At present, the heap of garbage has reached up to 40 metres. Although the dumping site falls in the flight runway funnel zone, the BMC has permission from Airports Authority of India to raise the heap up to 84 metres.

Following an incident in Delhi, officials also aim to prevent the collapse of garbage mound at Deonar. “The vinyl sheet is comparatively stronger than concrete and can face garbage pressure at creekside. It is used worldwide due to sustainability against leachate,” said an official from the BMC.

Last year in August, a heap of garbage collapsed in Bhalswa landfill in Delhi, injuring three rag pickers. In November 2020, the civic body approved a proposal of appointing a contractor to set up a “waste to energy” plant at Deonar dumping ground. The plant will come up on 12 hectares of land identified inside the dumping ground. The project will cost the civic body Rs 1,020 crore and will be completed in 40 months. The contractor will maintain the plant for the next 15 years.

Earlier, the Shiv Sena had stalled the proposal alleging malpractices in the awarding of the contract for the waste-to-energy plant. The party demanded that the contract should go to the second lowest bidder. Later, however, the Sena cleared the same proposal.