The engineering director of CMWSSB G Elangovan told Express that the board is taking necessary action to arrest these discharges by carrying out various improvement works.

“We are increasing the pumping capacity and sewage collection system capacity wherever required,” Elangovan said, adding that sudden increase in population after the project was formulated has put pressure on pipes, where the sewage flow as reached the utmost level.

Elangovan said the final treated effluent by sewage treatment plants into the water courses conform to the standard prescribed by the Tamil Nadu Pollution control Board. The treated effluent is meeting the design standards of biochemical oxygen demand (BOD), suspended solids (SS) and focal coliform.

The initial Rs 1,700 crore CCRP project, which was later modified to Rs 1,200 crore following reduction of about Rs 500 crore in the component for rehabilitation and resettlement of slum dwellers living on the banks of waterways, was to plug the outfalls in Adyar River, Cooum River, Buckingham Canal, Otteri Nullah, Captain Cotton Canal and Mambalam drain and prevent untreated sewer from reaching the waterways.

“All the works have been completed and commissioned. Because of the completion of these works the sewer overflows have been considerably reduced and diverted to the sewage treatment plants. Further, the sewage treatment plant capacity also increased from 222 million litres per day (mld) to 486 mld,” he said.

Elangovan said the project consists of 16 packages. “In certain components of four packages, certain defects such as joint leaks and sinking of manholes have been noticed at 41 locations. Since these works are within defect liability period, the Board is attending the defects at the risk and cost of contractor,” he said.

“So far defects at 19 locations have been attended and defects at remaining 22 locations are being attended. Notwithstanding these defects, the systems are functioning and the sewage is being conveyed to the concerned pumping stations and treatment plant for regular treatment,” the director said.