Southern Environmental Services workers peeled back layers of copper-colored clay Tuesday to reveal six side-by-side underground storage tanks that were steps away from Key Oil Co., which began the process of replacing its nearly six decade-old gasoline infrastructure in Bowling Green.
Two months before this undertaking, Lost River Cave staff found strong gasoline odors emitting from the cave. This led to an investigation and a state emergency declaration from the Kentucky Energy and Environment Cabinet.
An underground storage tank remains the expected source of the gasoline release. Gasoline can spill when fuel is transferred between tanker trucks and storage tanks, and steel tanks or pipes that connect the tanks to the pumps can corrode and leak. However, there has not been conclusive evidence as to where the release originated, according to Kevin Strohmeier, response coordinator for the Environmental Response Branch of the Kentucky Department for Environmental Protection.
In May, Strohmeier injected red, pink and orange dyes in several locations connecting to the karst stream network to see “where the dye travels to and how long it takes to get there.” There was a direct connection between Key Oil Co. and Lost River Cave, but other nearby gas stations that weren’t tested could also be directly connected to the cave, Strohmeier said.
In light of the investigation, Key Oil Co. voluntarily decided to replace its aging underground storage tanks with modern alternatives.
Southern Environmental Services workers contracted by Key Oil Co. excavated the site Tuesday while local and state environmental experts involved in the investigation oversaw the work. They expected to continue excavating through Wednesday or beyond.
The six tanks, each equipped with automatic tank gauging for release detection, measured about 32 feet long and sat abreast in thick clay. There were some gray spots in the clay, indicating the presence of gasoline, but the initial excavation did not provide soil evidence of a spill, according to Strohmeier.
With the emergency declaration, the cabinet ordered the examination of nine gas stations in the Lost River Cave vicinity. Key Oil Co. had the oldest tanks in the area – dating back to 1962.
No other gas stations in the area volunteered to replace their systems.
“It’s such an expensive proposition that no one does this for any other reason than (long-term) economics,” Strohmeier said.
Although it’s been challenging to find the source, several environmental experts continue to hunt for answers.
Jason Polk, a geologist and Western Kentucky University professor who helped oversee the work Tuesday, has been climbing into caves for the past two months to search for clues. He’s actually been caving for years, helping map Bowling Green’s underground landscape. But even with his experience, water pathways through the karst remain complex.
“There’s all these different routes,” Polk said. “It’s not uncommon to see rivers flowing in top of each other.”
Strohmeier, who will continue to monitor gasoline vapors and water quality in the area, remains optimistic. He hasn’t accepted that they won’t ultimately find the answer.
Key Oil Co. did not respond to a request for comment.
Since early May, Strohmeier has been monitoring benzene, toluene, ethyl benzene and xylene, which are the worrisome volatile organic compounds present in gasoline vapors, at multiple sites, including Lost River Cave, Lost Circle and a recently discovered sinkhole near Nashville Road.
In the past month, total VOC readings at the sinkhole site have remained at low levels, at around five to 10 parts per million, with a slight jump during a half-inch rain. But there was a “spike” over the weekend.
At noon Sunday, VOC readings in the sinkhole site jumped up to 400 ppm after a few days of continuous rain. The reading dropped back to a low level by Monday.
It’s unlikely there’s any additional leaking occurring, but the rain “mobilized fuel that’s tied up in either pools or rocks,” Strohmeier said.
There were no spikes at Lost River Cave or at the Lost Circle location, which both had very low or non-detects for more than a month.
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