A gasoline spill from a gas station’s underground storage tank led to temporary evacuations and the closing of gas pumps, but it was a “miracle” the incident wasn’t worse, according to an Indiana Department of Natural Resources official.
As previously reported by the Kokomo Tribune, the underground storage tank that housed the premium fuel for the Marathon gas station at 2105 S. Washington St. in Kokomo suffered a leak.
Approximately 0.8 gallons leaked per hour by the time it was discovered in late September. The leak caused the city to close down West Boulevard Street between South Washington and South Webster for a few days, the temporary evacuation of some nearby residents after they smelled gas vapors in their homes and shut down the business’ gas pumps until new underground storage tanks could be installed.
While it’s still being decided if there was any groundwater contamination caused by the leak, the worst — a potentially dangerous explosion — was avoided, according to an email sent from David Cage, an emergency response on-scene coordinator for IDEM, to city officials and others, as well as Cage’s emergency response report.
In the Sept. 23 report, Cage wrote that the calculated lower explosive limit for the gas in the city’s sanitary sewer and “several homes” in the area was at 100% for much of Sept. 23.
The lower explosive limit (LEL) of any given gas is the lowest point of concentration at which it becomes flammable in the atmosphere. A 0% LEL suggests a combustible-free atmosphere, while a 100% LEL means if the gas were exposed to a spark or some kind of ignition, it would be highly flammable and could create an explosion.
In a Sept. 27 email to city officials and others, Cage thanked the Kokomo Fire Department and city personnel for their quick response to the incident.
“With LELs at 100% for a good part of Friday, it’s a miracle that nothing worse happened,” Cage wrote. “Your efforts helped avoid the worst case scenario. Thank you.”
To abate the issue, KFD vented both the nearby homes and sanitary sewer system.
By Sept. 26, all LEL levels in the homes and all but one sanitary sewer were at 0%. The fire department continued to vent the one manhole that was reporting between 5-6% LELs until Sept. 28 when it finally reported 0% LELs.
As of Tuesday, the pumps at the Marathon gas station are still closed.
The land owner of the property, Good Oil Company Inc., was ordered to install monitoring wells in four soil borings to determine any groundwater contamination.
According to an Initial Site Characterization (ISC) filed Nov. 23 by SESCO, an Indianapolis remediation company, the monitoring wells could not be installed properly because the drill ran into subsurface slag.
In the ISC, SESCO says “alternative drilling methods” are needed to properly install the monitoring wells, suggesting sonic drilling be used. That appears to be the way the company has decided to go.
According to an early December email uploaded to IDEM’s Virtual File Cabinet between SESCO and IDEM, the remediation company was actively seeking bids from companies to perform sonic drilling.
Vapor samples from four nearby sewer lines were also collected. Results from the vapor samples reported that all relevant and analyzed concentrations were below detection limits.