The Kolkata Municipal Corporation will start building drainage lines under 137km of roads in parts of Sarsuna, Joka and along EM Bypass that lack underground drainage.

It will be part of a recently sanctioned ₹2,500 crore project, a majority of whose funding will be from an Asian Development Bank loan.

On Monday, mayor Firhad Hakim announced that work under the project, named KMC Sustainability, Hygiene, and Resilience (Sector) Project (KMC SHARP), will begin after Puja.

According to sources, the projects must be completed by 2032, as per the loan and project agreements signed among the Centre, the state, the KMC, and the Asian Development Bank (ADB).

“We will lay new drainage lines in Wards 108, 109, 127 and 142. These areas lack drainage lines,” Hakim said after chairing a meeting of senior officials.

KMC sources said drainage lines will also be laid in Wards 126 and 143.

Ward 109 covers parts of Mukundapur; Ward 108 covers areas like Anandapur, Chowbhaga and Panchannagram; Ward 126 and 127 cover Sarsuna-Oxytown, Shakuntala Park-Sonamukhi; and Ward 142 and 143 cover parts of Joka.

Drainage lines will be built in Nayabad and Ajoynagar in Ward 109; Anandapur in Ward 108; Julpia and Kabardanga in Wards 142 and 143; and Sonamukhi Main Road, Kastodanga Road and Jadav Ghosh Road in Wards 126 and 127.

“Earlier, sewage used to be drained into canals through natural slopes and the flow of drains. Such drainage without treating the sewage is prohibited now. New drainage lines, along with sewage treatment plants that will treat the sewage, will be built under the project,” Hakim said.

According to sources, while several areas have underground drainage lines, these are inadequate or used to drain sewage into canals without any treatment. On some other stretches, there are no drainage lines at all, and a new underground network has to be built.

“Ward 127 has almost no underground drainage network. Complaints often raise the issue with the mayor,” said an engineer.

Of the 137km, 71km would be trunk sewer lines under main roads of the neighbourhoods, and the remaining would be lateral sewer lines under branch roads.

This is the third project under the KMC for which ADB has released loans to develop a drainage network. The two earlier loans were used to build both water supply network and drainage infrastructure.

Kolkata Environmental Improvement Project (KEIP), initiated in 2006, and the Kolkata Environmental Investment Improvement Project (KEIIP), which began in 2013, developed drainage and water supply lines in Behala, Tollygunge, and several areas along EM Bypass.

The previous two projects cost ₹7,884 crore. “A majority of funding for all the projects came from loans sanctioned by the ADB. The ADB provides 70 per cent of the project amount while the state government and the KMC divide the rest between them. The state pays 65 per cent of this, and the KMC pays the remaining 35 per cent of the project cost,” said an official.

Complaints about roads remaining broken and dug up for months for the drainage work have flooded the civic body.

On Monday, Hakim said all roads have been relaid except for eight in the Bakrahat area, where drainage work is on.

“We are working fast to complete all pending work, and we will take up the new project soon,” said Vishwanath, the project director of KMC SHARP.