Petroleum Release from Underground Pipeline
Tondiarpet, Chennai, India

Stratus signed a contract with Bharat Petroleum Corporation, Ltd. (BPCL), to assess and remediate a petroleum pipeline leak in Chennai, India. Due to a failure of pipeline integrity, gasoline and diesel were released to the subsurface from BPCL's pipeline connecting their marine petroleum off-loading terminal on the Bay of Bengal to their main petroleum distribution terminal. Use of the failed pipeline has been terminated, but the release occurred in a densely developed urban neighborhood, and has affected numerous local domestic and commercial water supply wells.

Beginning in early 2015, Stratus initiated a site characterization program to evaluate the vertical and lateral extent of the release and estimate the mass of petroleum still in the soil and groundwater. Stratus' proposed approach will be to install 20 groundwater wells to 50 feet below ground surface (bgs) and 10 groundwater wells to 80 feet bgs to characterize the impact in both groundwater and the vadose zone (unsaturated soil column). Data from these wells will be combined with analytical data from existing domestic supply wells and previous work performed by the Indian Institute of Technology Madras to develop a comprehensive conceptual site model (CSM), including modeling of groundwater flow and contaminant fate and transport.

Up to 25 soil gas monitoring points will also be installed to evaluate concentrations of volatile petroleum vapors beneath residential and commercial buildings in the immediate vicinity of the release. Analytical data from these monitoring points will be incorporated with the CSM to quantify the human health risks associated with the release of these petroleum products in a dense urban setting. This work in expected to be completed by July 2015.

Removal of free-phase product from the existing domestic supply wells will begin immediately. Any of the newly installed monitoring wells that contain free-phase petroleum will be included in this program.

Based on available information from the site and contract requirements, engineered remedial efforts will consist of soil vapor extraction (SVE) to remove petroleum from the vadose zone, and air sparging (AS) to reduce concentrations of dissolved petroleum. Pilot testing of the proposed remedial technologies will be initiated immediately following completion of the CSM. Assuming no major obstacles are identified during pilot testing, Stratus will import and install the remediation equipment (oxidizer and compressor) and additional required remediation and injection wells, with full remedial operations online by October 2015. Based on available data, Stratus anticipates the remedial effort will be completed within three years.

This project presents several significant logistical problems. The release occurred in a highly developed, densely populated area. Municipal and private open space areas are limited; well drilling and remediation piping installation will take place mainly in the crowded, densely travelled public streets and alleyways. Stratus and BPCL have initiated a program of public outreach to inform residents and municipal officials of the proposed remediation program, and to solicit municipal and public cooperation for timely completion of the cleanup.