BP 11255

The property located at 19924 International Boulevard in SeaTac, Washington is an active convenience store and gasoline facility. In April 1991, a subsurface investigation was conducted to evaluate soil and groundwater conditions in the vicinity of the USTs and associated product piping at the property. Soil and groundwater analytical results determined that petroleum hydrocarbons were present at concentrations exceeding the Washington State Department of Ecology’s (Ecology) Model Toxics Control Act (MTCA) Method A Cleanup Levels. The property was entered into Ecology’s Leaking Underground Storage Tank (LUST) database in March 1992 following additional investigation conducted in January 1992. Based on the location of soil and groundwater impacts, the likely sources are the dispensers located in the central western portion of the property, and the associated product piping. The investigations completed to date defined the majority of the subsurface impacts to be in the southern portion of the property and extends off-site into South 200^th Street.

Between June 2010 and June 2013, Antea Group conducted four subsurface investigations to further delineate soil and groundwater conditions as well as isolate the source of petroleum hydrocarbon concentrations in groundwater.  The investigations included the installation soil vapor exaction wells, air sparge wells and several injection wells.   From January 2012 through August 2013, several remedial options were pilot tested to evaluate effectiveness. Antea Group, with technical assistance from Ecology, is currently evaluating remedial alternatives to address the subsurface impacts remaining at the property.