CHENNAI: A CAG report tabled in the Tamil Nadu assembly exposed the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB), known as Metrowater, for its poor performance in maintaining sewerage in the Chennai Metropolitan Area (CMA) till March 2019.
The report was submitted to the government on November 13, 2020, but was not tabled till date.
The CAG estimated that 24.27 crore litres of raw sewage enter Chennai’s water bodies — Cooum, the Adyar river and Buckingham canal — daily.
This is because only 52% of sewage generated in the CMA is collected by the existing system.
In addition, 88% of collected sewage is treated before being let out.
This polluted water bodies with biological oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) at 15 times the normal value.
The CAG also pointed out that an underground sewerage system (UGSS) was not provided to 31 of the 42 areas — seven of the eight municipal towns, 10 of the 11 town panchayats, and all 10 panchayat unions — added to Greater Chennai Corporation (GCC) in 2011.
This was because of poor planning, lack of coordination with line departments, and delays in tender approvals.
In the Thiruvottiyur UGSS project, Metrowater allowed an inefficient contractor despite rating him poor in May 2013 itself.
In tenders pertaining to plugging sewage outfalls in water bodies, CAG found CMWSSB’s board took 11-25 months just to accord approval.
The local bodies minister is the chairman of the board.
The audit also found poor record-keeping of collection of sewage in areas in Chennai’s peripheries and monitoring of sewage tankers dumping waste into waterbodies.
At sewage treatment plants (STPs), all quality control tests were not being done which meant that they were not able to analyse the presence of industrial waste in the treated water.
The report also found that five STPs had no biogas plants and in three, these were non-functional.
Due to this, 57 lakh cubic metres of methane gas per annum was released into the atmosphere while CMWSSB could have saved crores on electricity bills by using these gases.