Residents first noticed the oil in mid-2012 and by July 2013, TNPCB intervened after media reports about the contamination. Experts from IIT- Madras were then asked to study and help decontaminate the locality. From February 2015, Stratus Environmental commenced studies to clean up the area. Stratus set up 30 bore wells to monitor how far the oil had spread. Fortunately, it had not spread much. Now, 20 remediation wells have been placed and through a soil vapor extraction system, oil in the sub-surface is removed. Using an air sparging system, oil in the groundwater is brought up by blowing bubbles into the water. Continuous samples of the water and soil will be collected and tested, explained an engineer who is familiar with the process.

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A U.S.-based company has begun remediation measures in Tondiarpet, Chennai where an oil leak from an underground pipeline had contaminated groundwater and soil. It has been two years since residents of T.H. Road and V.P. Koli Street in Tondiarpet found their bore wells and open wells unusable, and have been using water supplied by the client. “Life has not been easy. Many tenants have moved away and the value of our property has gone down. Water in surrounding wells too has become contaminated. We are not sure how far the leak has spread underground. We are hoping the remediation process restores normalcy,” said a resident. Sources at the major oil company, whose oil pipeline had leaked, said the clean-up had commenced recently with the U.S. Company, Stratus Environmental Inc., surveying the locality and removing oil floating on groundwater.

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This is the first stage of the process and is likely to take 48 months or more. Petroleum-absorbent socs (sponge-like products) are being used to remove the oil. The second stage will involve installation of monitoring borewells, collection of soil samples, and analysis of these in a laboratory to evaluate the lateral extent of contamination in soil and groundwater. The third stage will comprise remediation of soil using a technology called Soil Vapour Extraction and the fourth stage will see remediation of groundwater. Stratus Environmental’s principal engineer, Gowri Shankar Kowtha, said his company had 15 years of experience in cleaning up such oil spills in the U.S. and recently, it had also completed a few projects for private companies in India.

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He said oil leaks from pipelines are inevitable and can be caused by various factors, including age and pressure differences. The Indian Institute of Technology-Madras and the Tamil Nadu Pollution Control Board will monitor the clean-up. Residents first noticed the oil in mid-2012 and by July 2013, TNPCB intervened after media reports about the contamination. Experts from IIT-Madras were then asked to study and help decontaminate the locality. From February 2015, the U.S.-based company began its studies to clean up the area. The company set up 30 borewells to monitor how far the oil had spread. “Luckily, it hadn’t spread much. Now, 20 remediation wells have been placed and through a soil vapour extraction system, oil in the sub-surface is removed. Using an air sparging system, oil in the groundwater is brought up by blowing bubbles into the water

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Continuous samples of the water and soil will be collected and tested,” explained an engineer who is familiar with the process.

Residents are happy to get an oil major to clean up its mess, but were now concerned over the compensation they will receive. “The value of our properties has dipped drastically. We buy drinking water. Our groundwater smells of oil emanating from the bores,” said a resident, who is awaiting the orders of the National Green Tribunal (Southern zone Bench) in the matter.