Test samples from six drinking water wells show no gasoline contamination resulting from a leaking underground storage tank at a closed Sterling gas station, according to an official with the Alaska Department of Environmental Conservation.
Recent tests revealed a foot of gasoline atop groundwater in the bottom of two 40-foot-deep monitoring wells near the Sterling Zip Mart, located on Swanson River Road just off the Sterling Highway. A leaky underground storage tank is the suspected source.
Nearby Sterling Elementary School, which had only recently switched its internal water system back on after copper and lead were discovered in the school well water, shut that system down again after learning of the gasoline contamination at the station. The school had been using bottled water for drinking purposes, Principal Paul Kubena said.
DEC officials warned the owner of a nearby residence, a business and two churches not to consume their drinking water until the samples were analyzed. The school's well water also was sampled. Results from two samples came back free of contamination late last week, the rest came back Monday, said Paul Horwath, of the DEC's Soldotna office.
"No contaminants were detected in any of the six drinking water wells sampled," Horwath said.
The six wells testing clean were at the school, the Sterling Baptist Church, the Sterling Lutheran Church, the Wash Out Laundromat, a private residence and at the school itself.
The clean results are good news, Horwath said, but DEC still plans to drill at least six more monitoring wells to see if the gasoline is migrating at all and in which direction. Testing will continue, he said.
Of major concern in gasoline contamination cases is the presence of benzene, a constituent of gasoline that is a cancer-causing agent. Allowable limits are 5 parts per billion in drinking water. Samples from the monitoring wells showed 60,000 parts per billion, according to Rachel Navarre, the Kenai Peninsula Borough's environmental compliance coordinator.
Horwath received word late Monday that all the samples had tested clean from Darci Bowers, an environmental scientist with Gilfilian Engineering and Environmental Testing, the Anchorage company hired to survey the groundwater by the Zip Mart's owner, Whittier Properties Inc.
The survey discovered the contamination in the monitoring wells in late December. DEC was notified Jan. 11.
The nearby drinking water wells were tested Jan. 16.
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