Groundwater around a former Sterling gas station is heavily contaminated with gasoline apparently leaked from a subsurface storage tank, state environmental inspectors said Friday.
The leak has raised concerns about the safety of drinking water in nearby wells, including one at Sterling Elementary School a short distance from the station. Currently, however, the school uses bottled drinking water because of an existing problem with the presence of copper and lead.
The Sterling Zip Mart, on Swanson River Road just off the Sterling Highway, closed last year. The contamination was discovered during environmental assessment work by Gilfilian Engineering and Environmental Testing Inc. of Anchorage, the company hired by the owners of the station, Whittier Properties Inc.
Tests of the integrity of the underground tanks conducted two years ago showed no indication of a spill at that time, according to an Alaska Department of Environmental Conservation press release Friday.
However, Paul Horwath, an environmental specialist with the DEC's Soldotna office, said tests done in 1995 when an underground tank at the station was upgraded revealed minor levels of contamination. The DEC had been encouraging more assessment work since then, he said, but little was done until Whittier hired Gilfilian late last year.
Gilfilian sampled the groundwater around the end of December and found the heavy contamination. DEC was notified of Gilfilian's test results Jan. 11, Horwath said.
The contamination is substantial, borough environmental compliance coordinator Rachel Navarre told the Kenai Peninsula Borough Assembly on Tuesday afternoon. She said inspectors found "a foot of gasoline" floating on top of groundwater collected at the bottom of deep monitoring wells. Water samples were found to contain the carcinogen benzene, a constituent of gasoline, at levels of 60,000 parts per billion.
"For reference, the drinking water standard is five parts per billion," Navarre said.
DEC officials warned local residents not to drink tap water at the Sterling Baptist Church, the Sterling Lutheran Church, a nearby laundromat and a private residence until the results of tests on samples taken from their wells Jan. 16 are known. So far, two wells showed no contamination. The results from the three others are expected within days, Horwath said.
DEC's advisement did not include Sterling Elementary School to the south-southwest of the contaminated site. Horwath said the state requires the school's water system be tested periodically. That was done most recently in early December, and no fuel contamination was found. As a precaution, the school's well was retested Jan. 16.
Existing problems with the school's water, specifically the presence of copper and lead, already required students and faculty to drink delivered bottled water, Navarre said.
At least that's what is supposed to be happening, said Donna Peterson, superintendent of the Kenai Peninsula Borough School District.
"We are on the phone as we speak trying to find out what's going on, because the plan is they're supposed to be on bottled water with cups," Peterson told the assembly.
Whether children were avoiding tap water was questioned Tuesday when assembly member Grace Merkes of Sterling said she and others with whom she plays volleyball routinely drink from the fountains in the gymnasium. She did not say she knew children were drinking tap water, but said a sign above the fountain said to run the tap for five minutes each day before school starts.
"The water's running during the day," she said. "We drink the water."
Navarre said that for lead and copper contamination, flushing the line alleviates any problem from those metals. She said she would ask the school district to make sure no one was drinking from the fountains at least until the results are back from the well samples.
Merkes said she wonders why the churches, the business and the residence were warned, but not the school.
Navarre said the copper and lead contamination problem at the school is "not cleared up yet," so there is no reason for the school to be off bottled water.
Merkes pointed out that the last known results are more than a month old. Navarre said DEC thinks the leaking may have started as far back as a year ago.
"It likely would have migrated that far if it was going to happen," Navarre said.
Paul Kubena, principal at Sterling Elementary School, said the school is on bottled water. Recent work on the water system had allowed the internal system to be turned on again, but mostly, bottled water is used.
Since being notified about the problem at the Zip Mart Jan. 17, the school's internal water system has been turned off, and will remain that way until test results show it is clean of fuel contamination.
"I don't think there is any need to alarm anybody," Kubena said.
Peterson said the drinking fountains have been turned off, though well water is still used for other things, like flushing toilets and washing hands.
Exactly how far the fuel may have migrated and in which direction is the focus of DEC assessment work going on now, Horwath said. According to data on groundwater movement acquired during surveys about 15 years ago, the direction contamination might be expected to flow would be south and east, but generally in the direction of the school.
However, DEC is not certain yet.
"We don't have high confidence in the direction of migration," Horwath said.
At least six more monitoring wells will be drilled to a depth of about 40 feet to get a better handle on the pattern of the contamination plume, he said.
At this point, DEC is concentrating on examining the migration. It has not begun to focus on a cleanup plan or on its potential costs.
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