747 MLD of untreated sewage let out into rivers - Hindustan Times
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747 MLD of untreated sewage let out into rivers

ByPrayag Arora-Desai
Jul 06, 2021 01:23 AM IST

A total of 747 megalitres of untreated sewage is released into four rivers in Mumbai each day, a civil appeal petition filed by the Municipal Corporation of Greater Mumbai (MCGM) in the Supreme Court (SC) stated

A total of 747 megalitres of untreated sewage is released into four rivers in Mumbai each day, a civil appeal petition filed by the Municipal Corporation of Greater Mumbai (MCGM) in the Supreme Court (SC) stated. These include the Mithi River, which receives the highest quantum of dry weather flow (DWF) at 285 megalitres per day (MLD), followed by Poisar river (67MLD), Dahisar river (56MLD) and Oshiwara river (17MLD). One megalitre is 1 million litres.

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BMC officials said tenders for infra works, which will divert sewage away from these water bodies and into the municipal treatment and disposal systems, are close to being awarded. Broadly, they involve laying down new sewer lines, building retaining walls, constructing small capacity sewage treatment plants and installing drainage interceptors at strategic locations. However, the commissioning of these works is still some time away. “As per National Green Tribunal’s (NGT) instructions, we have floated the tenders. Financial packages have also been opened, and we’re in the final process of awarding the work to contractors. But the work, undertaken as part of the municipal sewerage improvement programme, is expected to complete only in three-four years,” said additional civic commissioner P Velrasu.

A review of MCGM’s submission to SC (challenging NGT’s order from last October order to penalise the civic body for repeatedly polluting city’s rivers, creeks and drains), however, reveals that the planned interventions may not be sufficient to fix the problem. “On completion of the river rejuvenation works, major DWF of 426 MLD will be diverted into the existing municipal sewer lines/STPs,” stated MCGM’s petition (a copy of which is with HT). This still leaves nearly 321MLD, for which MCGM does not seem to have a clear action plan, as per documents. “This is a glaring problem which MCGM has not even acknowledged before SC,” said Stalin D, director of NGO Vanashakti, whose petition in NGT led to its October order. Velrasu said, “We’ll aim to divert as much untreated sewage as possible, as well as reduce the quantum of DWF being generated.”

Meanwhile, MCGM has proposed to carry out a range of infra works along the Mithi River in four packages. In package one – which runs from Filter Pada to the WSSD Garage in Tilak Nagar – an 8MLD STP is being built for the treatment of wastewater to meet revised effluent standards, as prescribed by NGT.

“The work commenced from 27.11.2018 and was likely to be completed within the period of 24 months. However, due to the present pandemic, the same is delayed... Due to the revision of the effluent norms the project extended further by 14 months and is scheduled to be completed by 31.12.2021,” the MCGM has told the apex court. Fresh sewer lines, 1.65kms in length, are also being built to channel DWF to the upcoming STP. Also, the construction of... 24 MLD Influent pumping station is in progress. The physical progress of work is till date 70% (sic),” stated MCGM’s civil appeal.

In package two (from WSSD garage to CTS Bridge) works are further divided into four different tenders. They include building an 8-km sewer, installing 102 drainage interceptors, building a retaining wall of about 3km and a service road of about 9km. Though the work order for these has been issued, MCGM has not specified the degrees of progress achieved as on date.

“Time period for package-2 works is 24 months (excluding monsoon months),” the corporation has submitted.

Work on packages three and four are yet to commence. Package three (from CTS Bridge to Mahim Causeway and Vakola nullah) involve construction of fresh sewers (8km), retaining wall (also 8km) and service roads (7km), in addition to installation of more drainage interceptors, gate pumps, sewage pumping stations, and beautification of the riverfront. It is unclear whether tenders for the works have been awarded. The specified time period for this work is at least 36 months.

Package four comprises construction of a 6.5-km tunnel to divert 168MLD of intercepted DWF (from Bapat and Safed Pool nullahs) to a proposed STP at Dharavi, which will be commissioned only in 2026. Tenders are invited. The contract period for the work is four years from date of award.

Similar interventions have been proposed along the Poisar, Dahisar and Oshiwara rivers. In all, about 17.5km of fresh sewer lines, 16.5km of stormwater drains, 16 drainage interceptors and 17 small capacity sewage treatment plants will be built over the next four years. Key locations for installation of STPs include Sukurwadi and Indira Nagar along Dahisar river; Kranti Nagar, Gokul Nagar, Durga Nagar, Poisar Subway and Sanjay Nagar along Poisar river; and area near Hindu cemetery in Aarey Colony, which is aimed at tackling a significant quantity of wastewater that is discharged from the dairy industry there.

The corporation has received 10 bids from contractors. BMC’s tendering process, their civil appeal shows, has been considerably delayed due to the pandemic. Tenders that were invited last April and May are yet to be awarded for works on the three smaller rivers.

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