The Alaska Department of Environmental Conservation has ordered the Anchorage-based parent company of a closed Sterling gas station to begin work this month to identify the extent of soil and groundwater contamination caused by a leaking underground fuel tank.
Heavily contaminated soil and groundwater were discovered at the ZipMart station on Swanson River Road early in January. An Anchorage engineering firm hired by the station's owner, Whittier Properties Inc., found a foot of gasoline floating on top of groundwater in two monitoring wells at the site.
Gilfilian Engineering & Environmental Testing Inc. notified DEC on Jan. 11 of the presence of large amounts of gasoline at the 37-foot level of the two 40-foot test wells, the same depth at which groundwater supplying nearby drinking water wells is found.
On Jan. 21, Gilfilian provided DEC with a proposed corrective action plan on behalf of Whittier. State law requires owners to supply such plans to the department in the event of spills or leaks. The work plan has been approved and work is to begin by Feb. 21, said Paul Horwath, an environmental engineer with DEC.
Among other things, Whittier will be required to determine the extent of the contamination, learn in which direction the fuel may be migrating, and remove and treat contaminated soil and groundwater. In addition, the company also must supply a sampling and monitoring plan for testing local drinking water wells and providing an alternative potable water supply for the ZipMart property.
Samples taken from nearby drinking wells in January showed no contamination from the ZipMart gas leak. But state environmental officials want monitoring to continue because the gasoline plum is likely spreading.
"Oh, it's moving," Horwath said Wednesday. How fast and how far it will go are the questions now, he added.
In a letter to Yovonne Kay Baker, treasurer of Whittier Properties Inc., Horwath said additional work would likely be required as additional information is gathered and reported.
"Due to the seriousness of this release and the need to protect public health, we must insist that corrective actions be implemented immediately," Horwath said.
Whittier was required to sign a written commitment and schedule for its corrective action this week. If that does not happen, ADEC would refer the matter to the civil division of the Alaska Department of Law for enforcement action, Horwath said. The department also could hire a contractor to do the required monitoring and cleanup work and then seek recovery of all costs from Whittier.
According to the work plan provided by Gilfilian on Whittier's behalf, six new monitoring wells will be installed in locations near the gas station, but most likely on neighboring properties, to define the extent of contamination.
Two months after the initial sampling, further sampling will be done at the five existing wells and the six new monitoring wells. Drinking wells down gradient from the ZipMart site will be tested as well.
Other work will determine how easily any free gasoline may be recovered from the ground. A technique under consideration essentially amounts to bailing the fuel from the wells on a periodic basis.
The work plan did not include removing the contaminated soil, but Darci Bowers, an environmental scientist with Gilfilian said that was "highly recommended." In a letter to Horwath outlining the work plan, she said that task and a schedule for it were not included in the current plan "in the interest o completing the next phase of release investigation as quickly as possible."
Whittier Properties operated regulated underground storage tanks at the ZipMart site from early 1990 until December 2000. According to ADEC, a new 20,000-gallon tank was installed in August 1995. Minor soil contamination and groundwater contamination at a depth of nine feet were reported at the time, but the extent of that contamination was never determined.
Gilfilian was hired in 2001 to assess the level of contamination from the 1995 report. During that field work the current serious state of contamination was discovered.
State officials immediately notified nearby property owners of a potential threat to their well water, and samples were taken and tested. So far, those wells are free of contamination, Horwath said last week.
Concern was heightened because of the proximity of Sterling Elementary School, which is generally in the expected path of the migrating plum of fuel. However, the school already is on bottled water because of copper and lead contamination in its own well. The school's well water will be monitored, ADEC said.
Representatives of Whittier, Gilfilian, and attorneys were meeting in Anchorage on Friday, according to Horwath, which was confirmed by a call to the office of Dale Dolifka, attorney for Whittier Properties.
Efforts to reach Whittier officials for comment were not successful by the Clarion's Friday deadline.
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