Emergency Response
11,000-Gallon Gasoline Spill, Detroit Reservoir,
Marion County, Oregon


Operating under the Unifed Command System which included representatives from the US Environmental Protection Agency (USEPA), Oregon Department of Environmental Quality (DEQ), US Forest Service (USFS), Oregon Department of Transportation (ODOT), Army Corps of Engineers, and the City of Salem, BB&A provided the technical lead in the environmental assessment and mitigation of a large gasoline spill which occurred along Highway 22 adjacent to Detroit Reservoir. Once spilled, the gasoline seeped into the drainage ditch along the north side of the highway, concentrating over an area approximately 200 feet in length. Six (6) days after the spill, low levels of dissolved gasoline constituents were detected along the shoreline within Detroit Reservoir, approximately 675 feet down slope of the spill site. The presence of gasoline vapors were detected over an area beneath the spill site encompassing approximately seven (7) acres.

Initial remedial efforts included removal of soils saturated with gasoline along the north side of the highway. Further excavation within the spill area was prohibited due to the narrow highway, steep slope, and underlying unstable geology. To determine the lateral and vertical extent of the gasoline, borings were advanced using coring techniques along the southern edge of the highway and along shoreline for the reservoir at the "high pool" elevation. The coring was brought to the shoreline by barge across the reservoir. The borings along the highway were completed as soil vapor extraction (SVE) wells. Within three (3) days of the spill, extraction SVE was initiated using a catalytic oxidizer and accompanying blower. The borings along the shoreline for the reservoir were completed as groundwater monitoring wells to depths approaching 70 feet. Additional assessment and remedial efforts performed at the site included vapor monitoring at various locations below the spill area within broken andesite talus, surface water sampling, and aeration (sparging) within the reservoir to remove and minimize the migration of dissolved gasoline constituents. Remedial efforts and natural attenuation have reduced the concentrations within the spill area to acceptable levels.