A year after a National Green Tribunal (NGT) order, the Brihanmumbai Municipal Corporation (BMC) has issued tenders revising the effluent discharge norms for its multi-crore Sewage Treatment Plants (STPs).
Under its Mumbai Sewage Disposal Project (MSDP-2), the BMC seeks to upgrade and construct STPs at Worli, Dharavi, Bandra, Malad, Versova, Ghatkopar, and Bhandup for treating about 2,460 million litres sewage water daily before discharging it into the sea or creeks. Apart from these seven, the civic body has recently completed upgrading an STP at Colaba.
On August 31, the BMC floated fresh tenders with new discharge norms which state biochemical oxygen dissolved (BOD) or dissolved oxygen level should be at 10 milligrams per litre (mg/L) and total suspended solids (TSS) at 20 mg/l for the STPs to be constructed on Design, Build, and Operate (DBO) basis. BOD and TSS are important factors to maintain the water quality.
This comes a year after the green tribunal, on July last year, ordered a change in the effluent discharge norms after a petition was filed against a notification of the Ministry of Environment, Forest and Climate Change (MoEF) that had set the parameters at 20 mg/l for BOD and 50 mg/l for TSS.
After the NGT order, the BMC had approached the Supreme Court, but got no relief. “We had to cancel the old tenders after the NGT ordered change in discharge norms. The delay and strict norms have led to an increase in the cost of the projects, as well as revision of the entire process of inviting new tenders,” an official from the MSDP department said.
According to officials, currently, about 60 per cent of the city’s population is not covered under the sewerage network and the existing STPs only do a primary treatment before discharging wastewater into the sea. The new plants are expected to carry out a tertiary-level treatment.
“These STPs will treat 2,464 million of litres per day (MLD), of which 50 per cent can be reused for non-potable purposes. All of the proposed plants will have BOD of 10mg/l,” Atul Rao, chief engineer, MSDP department, said.
Once the contractors are appointed, officials said, it will take four to six years to complete the upgrading and construction of the STPs. A source from the MSDP department said it is expected to cost around Rs 20,000 crore.
Pending for years, the project has seen multiple cost escalations.
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