The audit report on the public sector undertaking for the year ended March 31, 2019, said as per the data provided by Tangedco on fly ash generation and utilisation, Tuticorin thermal power plant utilised 100 per cent of the ash generated while Mettur stage I and II utilised 66 per cent and 78 per cent respectively. But the North Chennai station I and II utilised only 41 per cent and 54 per cent of the ash generated. It said only 4.40 million metric tonnes (MMT) out of 8.78 MMT (50 per cent) was utilised by the NCTPS I and II in the five years ending 2018- 19. The balance quantity of fly ash (4.38 MMT) together with the quantum of unlifted bottom ash and wet ash was transported to the ash dyke. Pointing to a notice issued by the TNPCB, the CAG report said TPS at North Chennai, Mettur and Tuticorin generated 28.19 MMT of bottom ash and disposed of 20.20 MMT during the period 2014-19.

“A quantum of 62.15 MMT of ash remained in the ash dykes in the three plants as of 31 March 2019. Thus, the continued dumping of ash in dyke resulted in contamination of groundwater in Buckingham Canal and Kosasthalaiyar river,” the report added. Based on a study conducted by the TNPCB technical team, the CAG said that the pollution control board directed the NCTPS to take remove 3.96 lakh MT fly ash deposited inside the plant, 0.93 lakh cubic meter tonnes of ash from Buckingham canal, and 7.93 lakh MT of ash from Kosasthalaiyar river. It also asked the Tangedco to replace 20.52 km of existing ash slurry pipelines and plant 6,000 saplings in and around the ash dyke to prevent dust emission. It noted that Tangedco yet to comply with the directions and pay Rs 16.46 crore environmental compensation levied on the plant for the period November 2004 to 2019. The report noted the government reply in October 2020 that the disposal of fly ash was satisfactory as per the environment ministry’s norms. “The pollution control measures are taken by Tangedo largely were inadequate in all the thermal power stations,” it said.