The Chennai Metropolitan Water Supply and Sewage Board (CMWSSB), popular as Metrowater, has chalked up a proposal worth `2,371cr to study and improve pumping stations, pipelines and the entire sewage infrastructure in the city to help it withstand emergencies like floods and cyclones. Technical assistance for the project has been sought from Japan International Cooperation Agency (JICA).
Another study would be carried out in March 2021 to assess British-era pipelines that are more than 70 years old. Based on the study and findings, proposals will be made and funds sought.
“The city has adequate infrastructure in terms of its population and sewage generation. It is only during the monsoon that we face problem of water stagnation, which results from surface water and rain water seeping into manholes,” said T Prabhu Shankar, executive director, Metrowater.
This year, Metrowater pumping stations received 450 million litres a day (MLD) extra rainwater in addition to the usual 550 MLD of sewage, which an official said caused a lot of pressure on underground pipelines. This resulted in pipes bursting in several locations causing water logging. With an eye on the future, it was decided to study these issues and come up with solutions to help respond quickly in similar situations next year onwards, the official said.
Currently, the city has about 12 plants treating about 727 MLD of sewage. The city consumes about 830MLD of water a day, with 80% coming back as sewage to pipelines. “Even if we consider the use of groundwater, our infrastructure can cater to double the quantity of sewage generated. It is the pipelines that are old and cannot carry more than their existing capacity. Our pumping stations and treatment plants continued to function for the entire monsoon season…
with primary treatment of water being undertaken before letting it out into the sea,” said the official.
Sewage pipelines in areas such as Nungambakkam High Road date to 1915. Anna Nagar, Egmore, Chetpet, Parry’s, Central, Sowcarpet and Anna Salai all have British-era pipelines. And even those laid in 1980s need to be replaced. “Most of these roads lie in the core city area with heavy traffic. It is difficult to close down these roads and replace the pipelines as we need to dig a minimum depth of 6m to 7m, blocking the entire stretch for a minimum of six months,” said an official. Keeping in mind these challenges, Metrowater has commissioned the study that has a deadline of December 2021.