Only half the sewage in Chennai Metropolitan Area being collected, says CAG report

CHENNAI: Only around half of the sewage generated in the Chennai Metropolitan Area (CMA) was collected by the existing sewerage system, leaving the remaining uncollected, according to the Comptroller and Auditor General (CAG) report tabled in the assembly on Thursday.

As of March 2019, only 52% of the sewage in the CMA was being collected through the sewerage system, leaving 48% uncollected. Of the collected sewage, only 88% was being treated before being let out, the report stated.

The audit stated that the government of Tamil Nadu, in response, said the claim that only 52% of sewage was collected was based on theoretical calculations. However, the CAG stated that the reply was ‘untenable’.

“.. the quantity of sewage is always worked out theoretically based on a scientific formula devised by the CPHEEO (Central Public Health and Environmental Engineering Organisation) and similar theoretical calculations are routinely used by CMWSSB for calculation of sewage generated in different parts of the city,” the report stated.

“The fact that 48% of the waste remained uncollected was an indicator of the enormity and seriousness of the issue,” the report noted.

Further, an estimated 242.73 mld of raw sewage illegally enters storm water drains and drains into water bodies including the Adyar, Buckingham Canal, Cooum etc. The plugging of polluted sewage outfalls into waterbodies, being executed under the aegis of the Chennai Rivers Restoration Trust (CRRT), remained ‘unachieved in full’ even four years after the scheduled date, the report stated.

The underground sewerage system, as on November 2019, was provided in only 11 of the 42 newly added areas while the entire Chennai Corporation area that existed before them were provided the underground drainage system, the report stated. It also noted the inordinate delays in completion of UGSS projects in Porur, Thiruvottiyur, Avadi, Tambaram, Ambattur, Karapakkam and Sholinganallur, Pallikaranai, Perungudi, Ramapuram and Nerkundram.

The CAG recommended an institutional mechanism for ensuring coordination of all line departments in implementing UGSS and ensuring availability of work site and all mandatory clearances from line departments before awarding tenders for UGSS, among other recommendations.