Even as the Congress has moved the Supreme Court alleging cost escalation in Mumbai Sewage Disposal Project-II (MSDP-II), the BrihanMumbai municipal corporation (BMC) has gone ahead and issued work orders for six of its seven sewerage treatment plants (STPs).

Last month the Supreme Court had directed the civic body to award contracts for STPs to the eligible lowest bidder before May 31, 2022. It also directed the municipal commissioner to personally monitor the progress of the tender process so as to obviate any bottlenecks in the decision-making process. The apex court also said that any party or bidder having any objection to the tendering process shall raise them only before the SC and no other court.

Stuck for nearly two decades due to changes in discharge and stringent treatment norms, space constraints, technical difficulties in construction, political fights etc, the projects have been delayed. The seven plants will now cost BMC almost Rs 26,000 crore due to the delay.

Located across different catchment areas of Mumbai, the projects are coming up at Worli, Bandra, Dharavi,,Versova, Malad, Ghatkopar and Bhandup, and have capacity to treat 2,464 million litres of sewage daily (MLD).

Construction of the state-of-the-art Colaba pilot project is completed and expected to be ready in two years. The plant will convert tertiary treated water into potable water and have capacity of 24-25 MLD. The plant will start at a capacity of 10 MLD and later scale it up to 25 MLD. This water will be required to be integrated with the existing pipe network.

The size and cost of projects vary. Malad and Worli, as master plants, will have capacity of around 450 MLD and cost Rs 7,103 crore and Rs 5,811.7 crore, respectively. The Bandra plant with 380 MLD capacity will cost Rs 4,293.3 crore.

The Ghatkopar plant will cost Rs 2,551 crore and the Versova plant Rs 1,603.8 crore. The Bhandup plant will have around 200 MLD capacity. The contracts have been awarded to Suez India and Suez International (Joint Venture), DRN Infrastructure Private Limited,  GVPR Engineers Private Limited, L&T Limited, NCC Limited, Welspun-EDAC JV and  JWIL-OMIL-SPML on design, build and operate basis where contractors will take approvals, design, build the projects and operate the project for a 15-year period.

Depending on the size, the project will take four to six years to complete. With land already available, smaller plants like those in Bhandup, Ghatkopar and Versova will be completed within three-four years and these locations are also away from the centre of the city. For the civic body, the Malad plant will be technically the most challenging and will take the longest time as it will have to be constructed on creek and not on land and will require the reclaiming of land. The marshy land will have to be piled, secured with perimeter, excavated and filled with hot soil. The project may take up to six-seven years.

As against ground floor structures, unlike other plants, the larger STPs at Bandra ,Worli and specially at Dharavi which is a tightly packed place due to space constraints will go up vertically 2-3 floors. For the Worli plant, which is spread on a larger area, many trees will have to be cut and transplanted.

However, the Bandra plant due to its proximity to the Sea link and keeping in mind aesthetics will have height restrictions. Worli, Malad, Versova, Ghatkopar and Bhandup plants are being set up at existing pumping stations. At Dharavi, it will be set up at Dharavi Maidan.

“The tenders have a legacy of getting cancelled and getting into controversy. There are many interest groups like technology groups, contractors’ groups, political groups etc, and maneuvering it is not easy. After many misses and the Supreme Court’s intervention, the faith it [SC] has shown in BMC and along with our updates, it has given us clearances. It has specifically said any objections with regards to these tenders have to come to SC only. This helped us a lot in playing extraordinary role and awarding the city with water,” says P Velrasu, additional municipal commissioner (Projects).

A critical reason for delay in the projects was meeting environmental clearances from MoEF and CPCB for Biochemical Oxygen Demand (BOD) and Total Solid Suspended (TSS) as the parameters kept changing. “Till the issue was resolved, BMC opted for the stringent condition i.e. 10 mg/l of BOD and 20 mg/l of TSS,” says Velrasu.

After financial scrutiny of these projects and considering aspects of front loading, back loading, construction time and payments to be made, BMC has now issued work orders for its six projects. The total cost of all seven projects is around Rs 26,000 crore, making it one of the biggest projects to have been undertaken by the BMC.

The exception here is the Bhandup plant, where the tender quotation with South Korean technology is 50% below expectations (translated into rupees, it stands at Rs 1,000 crore) as compared to six other tenders than expected. “While in theory it appears good, our team will be going to South Korea on June 6 to examine this CSBR (constant level and continuous flow sequential batch rector) technology. Once we are convinced, we will go ahead. As of now all out other 6 projects are good to go,” says Velrasu.

CSBR is an aerobic treatment technology used to treat municipal sewage and sewage from industries including refineries and petrochemical plants.      

Mumbai has a population of over 12.5 million. BMC supplies 3,850 million (385 crore) litres of water to the city every day. After usage, 75% of this water is released into lined/underground sewerage system. Mumbai generates around 2,400 million litres of sewage every day. The city’s 150-year-old sewarage line network is 2,025 km long and covers only around 60% of its population. BMC is in the process of laying new lines. Many areas like informal habitations and slums do not have sewerage network and large part of such houses are illegally connected to storm water drains, open nullahs and creeks.

“With focus on climate change and sustainable environment, several countries across the world get their drinking water from desalination plants which is almost similar with recycling. We are still not doing it. To provide 1,800 MLD water without recycling and reuse is the best option for the city of Mumbai. Keeping sustainable development in mind you get more water by either constructing new dams, adopting new technology or recycle and reuse which is the most sustainable,” says Velrasu.

While BMC has had plans to construct new dams, Gargi dam is supposed to provide 400 MLD drinking water. To execute this plan 3 lakh trees have to be cut which BMC wants to avoid. Another deterrent is that it is also close to Tansa Reserve. In such a scenario, the alternative for drinking water supply is these potable water plants.

Velrasu further explains that to make the water safe for human consumption it has to be tertiary treated which too does not remove microbes. “To get potable water we will tertiary treat water followed by three step process. All our plants now have been tertiary treated and 80% (of 2,400 MLD of water) can be easily recovered as drinking water after further processing of this water. This will provide us 2,800 additional MLD of drinking water, in addition to 3,850 MLD water we are supplying today. Six years down the line we will have this additional water.”

With SC greenlighting the STPs, BMC however is also prepared to face further resistance and opposition to treated water. “We are expecting opposition and debate to treated water. It is part of the process we have to undergo and setting in motion now. We have earmarked up to three years as convincing and education period. We estimated the projects may take 4-5 years to complete. By the time water will be freely available in all 6 STPs,” says Velrasu. “Adopting maximum transparency last year, we had to even cancel tenders. Many successful bidders have changed. And technology also has changed. In the process we too are learning,” he adds.

While it is always good to have larger plants where city wide piped network gets the sewage to the plants, for BMC it augurs well to have small treatment plants of 1MLD-2MLD capacities at these localities and connect pipes to these plants. Under the present situation BMC is adopting a mixed approach where in its river rejuvenation projects at Dahisar, Poisar and Oshiwara it plans to have many small STPs.

The projects will generate employment opportunities in electrical, mechanical, panels, pumps, and construction industry. Post completion as the projects will be highly automated and not much manpower will be required to operate them. After treatment of water the residue sludge will be converted into bio-fertilizers which could be used in BMC gardens department t or distributed to nearby farmers. Going ahead there could be revision in water tariff. At present water supply cost in the city is cross subsidized and 25% of actual cost.