CHENNAI: The Indian Coast Guard has estimated that 24,000 litres of oil might have spilled over the water surface during the recent Ennore oil spill, for which the state government has squarely blamed the Chennai Petroleum Corporation Limited (CPCL).
This is the first official assessment done after the oil spill last month, which polluted Ennore creek, Buckingham Canal, Kosasthalaiyar River and the coastal waters. The coast guard assessment was submitted by the Tamil Nadu Pollution Control Board (TNPCB) before the southern bench of the National Green Tribunal (NGT) on Thursday.
As per an aerial survey undertaken on December 16 by the coast guard, it was observed that most of the oil was deposited on the banks of Buckingham Canal, and Kosasthaliyar River, while the floating oil was observed to be leached from sand. Maximum oil spilled over surface water in these areas was calculated to be around 11.62 kilolitres (KL). Further traces of spilled oil were found on an approximately 20 sq. km area outside Ennore Creek.
“Based on the video footage, the quantity of oil spilled at sea was calculated to be around 12.4 KL. Thus, around 24 KL of oil has been calculated to be spilled over water due to the incident,” the coast guard said as quoted in the TNPCB affidavit, a copy of which has been accessed by TNIE.
Meanwhile, a detailed physical assessment of the quantum of oil spilled, carried out by IIT Madras is still awaited. The government had entrusted the IIT to study oil depth in canals, water and sediments using drones, ocean spill models and satellite imagery.
The institute has furnished a proposal to conduct an environmental impact assessment study of oil spill-affected sites at the Ennore Creek at a cost of Rs 1.04 crore, to devise a Management Act Plan for restoration and rejuvenation. The IIT has already conducted a physical survey and found 19 areas to be contaminated by oil.
Oil ‘leaked’ from CPCL: PCB
As per the response from the TNPCB, going by variation of the oil and grease levels in water bodies, oil was clearly leaked from the CPCL upstream and downstream. Around 828 mg/L of oil and grease and 48.4 mg/L of Total Phenolic Compounds was observed in the sample collected at Ennore Creek Bridge on December 5 as against the standards of 10 mg/L and 1 mg/L. This indicates the high oil content in the water bodies.
On December 7, five samples were collected along the Buckingham canal stretch and near CPCL campus and the oil and grease value was varying from 28 mg/L at the Buckingham canal, near IOCL gate, and Tondiarpet, to 158 mg/L at Ennore creek. This report clearly indicates that oil and grease value in the Buckingham Canal upstream of CPCL was lower compared to its level in the Ennore creek which is downstream of CPCI. “Clearly, oil leaked from CPCL,” the TNPCB report said.
However, this was heavily contested by the CPCL counsel before the NGT, claiming that the firm was being unfairly accused. The counsel alleged that the TNPCB, till date, did not visit the other unorganised units in the Manali area, which were also flooded.