Phase II of the work to clean up the oil contamination in Tondiarpet in north Chennai has begun with a U.S.-based company commencing drilling borewells on Tuesday. The oil had seeped into the ground over time from an underground pipeline that carried petroleum products to Bharat Petroleum Corporation’s facility at Tondiarpet.
Water in several open wells and borewells in the area have been contaminated with the oil. Though BPCL has been pumping out a mixture of oil and water for several months now there seems to be no reduction in the contamination, say residents.
“We hope that by next year our water would become potable like it was earlier. We have been using water supplied by the oil corporation since last year,” said a resident.
Sources in BPCL said that the remediation work, which will be carried out in phases, is being carried out under the supervision of experts from IIT Madras and Tamil Nadu Pollution Control Board.
Gowri Shankar Kowtha, principal engineer, Stratus Environmental, Inc said that the company planned to drill remediation and sample borewells at 37 locations. “These will help us lift soil samples and to check the level of soil and ground water contamination. The bore drilling process will get over in a month after which the system of remediation would be designed and installed,” he said.
The proposed cleanup of contamination at the Tondiarpet site will have four stages.
Stage 1 will consist of completing a survey of the area using a land surveyor and removal of oil floating on water (free product). We have started both activities and brought in petroleum absorbent socs to remove free product.
Stage 2 will consist of installation of monitoring bore wells, collection of soil samples and analysis of these in a laboratory to evaluate the lateral extent of contamination in soil and groundwater. To execute this phase of the project, Stratus will be bringing in a hollow stem auger rig. This rig is a specialised machine built for environmental work and reduces/eliminates cross contamination typical in commonly used drill rigs.
Stage 3 will consist of remediation of soil using a technology called Soil Vapor Extraction using a Catalytic Oxidizer, which is being brought into India as well.
Stage 4 will be remediation of groundwater using a technology called Air Sparging.
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Recent leaks in north Chennai
September 16, 2012: Leak in IOCL pipeline carrying CPCL product at Tondiarpet Kummalamman Koil Street
October 1, 2012: Leak in BPCL pipeline near the Tondiarpet railway station
April 24, 2013: leak in IOCL pipeline at Kasimedu fishing harbour
June 24, 2013: Leak in IOCL pipeline carrying lube oil from CPCL to Chennai Port, Kathivakkam high road, Tondiarpet
June 9, 2014: Leak of IOCL’s oil pumped by CPCL from its Manali refinery to oil tanker at Chennai port. Leak happened on Ennore Expressway July 16, 2014: Oil found in wells and borewells in homes in Tondiarpet
