Chennai's sewer system to be upgraded at Rs 689 cr

CHENNAI: The State government has given in-principle approval for a Rs 689.40 crore project to upgrade the sewerage system under the Nesapakkam sewage treatment plant (STP) catchment, where ageing infrastructure has led to frequent sewage overflows and pumping failures.

The Nesapakkam STP, commissioned in 1974, has a total treatment capacity of 144 million litres per day. Sewage from the catchment is conveyed through a network of gravity sewers and pumping mains to the treatment plant for processing and disposal.

The project proposes replacement or enlargement of 176.96 km of gravity sewer lines, covering about 54% of the catchment's collection system and around 63,000 households. A total of 7,807 manholes will be constructed or replaced. Pumping mains will be upgraded and six sewage pumping stations rehabilitated.

A centralised SCADA system at the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) head office will monitor sewage levels, pressure, flow, power supply and pump operations. The existing system at the Nesapakkam STP will be integrated to track treatment parameters, while odour control systems will be installed at all pumping stations.

To reduce disruption, sewer lines will be laid using trenchless methods such as horizontal directional drilling and pipe bursting. The project will be executed in four packages over three years with Asian Development Bank funding and is expected to benefit about 1.16 lakh households.