State environmental engineers may next try blowing air into the groundwater to force spilled gasoline vapors to the surface for collection near the defunct Zip Mart gas station in Sterling.
In the meantime, owners of contaminated property in the affected area near the Sterling Highway and Swanson River Road have received some monetary compensation from the gas station owner’s insurance company.
In early 2002, an engineering firm hired by Zip Mart owner Whittier Properties Inc. found heavily contaminated soil and groundwater. A foot of regular-grade gasoline was found floating on top of ground water in two monitoring wells at the site.
A Department of Environmental Conservation investigation revealed a fill pipe was not properly connected to underground storage tanks at the gas station and much of the gasoline being delivered was not getting into the tanks, but was spilling into the surrounding ground.
Because the ground pollution threatened drinking water wells at the nearby Sterling Elementary School, Sterling Baptist Church, Sterling Lutheran Church and several private businesses, monitoring and recovery wells were drilled.
Benzene contamination was found in the drinking water well at B&D Auto and Denny’s Auto Body, one-quarter mile from the closed gas station.
Due to some Zip Mart record keeping discrepancies, estimates of how much gasoline actually leaked into the ground vary from 50,000 to as high as 120,000 gallons.
The gas station opened in the mid-1980s and was operated by Whittier Properties from 1990 until being shut down in 2000.
On Tuesday, DEC’s Jim Frechione, contaminated sites program manager, said 14,791 gallons of “free-phase” gasoline were recovered from the ground as of June 2005, and a decision was then made to convert to vapor recovery.
Since that process began, an estimated equivalent of 2,100 gallons of product have been extracted in vapor form.
Monitoring wells being used to track the southeasterly spread of the plume of underground gasoline vapors benzene indicate it continues to migrate slowly, according to Frechione.
He said DEC is in the process of putting in another monitoring well and putting in a plan for additional treatment of the contamination.
Under consideration is “soil vapor extraction or air sparging,” Frechione said.
The process involves injecting oxygen into the water table to bubble up the benzene to the surface where the vapors are collected and treated.
“It’s still in the developmental stages, but we could have something by mid-March,” Frechione said.
Last year, DEC installed a vapor extraction system that removes the benzene through seven product recovery wells.
The benzene is vacuumed from the ground and treated in a thermal oxidizer that heats the vapors to 1,400 degrees Fahrenheit. The oxidizer can treat 20 pounds of hydrocarbons per hour.
Frechione said the oxidizer began treating vapors in June.
One affected property owner said because of the contamination, banks won’t lend money on any of the affected properties.
“We won’t be able to get any retirement out of this property,” said Royce Marlowe.
“We can’t sell it,” she said.
In her opinion, the DEC waited too long to take corrective action.
The spill came to the attention of DEC in 2001, Frechione said at a community meeting in Sterling in October 2004.
Marlowe said a group of property owners partially settled out of court last fall.
“We’re not done,” she said.
Because of additional aspects of the settlement that are still pending, those involved said they are not allowed to discuss an actual dollar amount of the settlement at this time.
When Whittier’s insurance company first announced a settlement, DEC said it planned to take 90 percent of the money as compensation for cleanup and monitoring work, leaving only 10 percent for affected property owners, according to state Sen. Tom Wagoner.
Wagoner said his office called DEC and told them he was going to introduce legislation mandating funds go to property owners.
“DEC backed off. They came on bended knee and said they would take 50 percent and leave 50 percent for (the property owners),” Wagoner said.
Kenai attorney Jim Butler, who is representing the Sterling Baptist Church, also one of the affected properties, said another aspect of the settlement a matter between Whittier and another insurance company is awaiting a court ruling on liability.
“Phase one of the settlement is resolved. We’re now hoping for resolution of phase two,” Butler said.
“Hopefully we’ll have something this spring,” he said.
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