Gas cleanup continues in 2010
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RONAN — The Conoco gas leak cleanup that began 15 years ago may be nearing an end, the Department of Environmental Quality reports.
Underneath the abandoned George’s Conoco building in Ronan lies the remnants of a 10,000-gallon gas leak that sprung from a perforated 16,000 gallon underground storage tank in 1994.
Since 1995, the DEQ has attempted to rid the ground of the gas plume that extends south and southwest to Spring Creek and is 70 feet deep, 1,500 feet long and 400 feet wide.
Previously, the Leaking Underground Storage Tank Trust funded the extensive cleanup process, which is 90 percent federal funds and 10 percent state matching funds.
But in February the American Recovery and Reinvestment Act, the stimulus package passed by Congress, funded the removal of the underground storage tanks and partially covered the final phase of the process which began in the spring.
In May, the DEQ began the third and final phase of the cleanup using electrical resistance heating coupled with air sparging and soil vapor extraction.
“The goal of this current phase of work is to clean up the remaining gasoline contaminated soil and groundwater in the vicinity of the former underground storage tanks,” DEQ Environmental Specialist Patrick Skibicki said.
In short, the electrical resistant heating process used by DEQ heats the subsurface soil and groundwater, while air sparging pushes air into the groundwater to drive the contaminants to the vapor phase. The soil vapor extraction removes the petroleum hydrocarbons from the subsurface.
Following the completion of the ERH phase in December 2010, the DEQ plans to monitor the groundwater to ensure the residual contaminants are naturally breaking down.
“The plume should shrink back more quickly due to the extensive cleanup measures implemented to address the source of the release,” Skibicki said.
Skibicki added that petroleum constituents have not been detected in Spring Creek’s surface water and there are no known impacts to public or private water supply wells, underground utilities or structures.
Though Skibicki warns future developments in the vicinity should take the dissolved plume into account, “it is DEQ’s hope that the former George’s Conoco property will be redeveloped in the future,” he said.
