Groundwater assessment for petroleum hydrocarbon compounds associated with Fuels Area C, Ellsworth Air Force Base, South Dakota, 2014–18

Abstract

and historical spills and releases in the area. The spatial and temporal variability in the BTEX compounds and naphthalene concentrations from samples collected from 2014 to 2018 do not indicate a consistent pattern of subsurface flow or contaminate movement that would be expected if a contaminant plume migrated with the flow and movement of groundwater.Gasoline-range organic and diesel-range organic compounds were detected in most of the groundwater samples collected in the study area around Fuels Area C in 2014-18; however, concentrations were often less than the laboratory reporting level. Median gasoline-range organic compound concentrations were greater than the laboratory reporting level at sites 1, 5, 9, 10, and 11. The highest concentrations of gasoline-range organic and diesel-range organic compounds generally were observed in samples collected from sites 10 and 11. Gasoline-range organic compound concentrations ranged from 1,500 to 9,700 micrograms per liter at site 10 and from less than 100 to 13,000 micrograms per liter at site 11. Diesel-range organic compound concentrations ranged from 9,600 to 55,000 micrograms per liter at site 10 and from 560 to 7,300 micrograms per liter at site 11. Study Area DescriptionFuels Area C (fig. 1) was constructed in about 1953 and has operated nearly continuously since construction (Tetra Tech Incorporated, 2008). The area is west of Ellsworth Street and covers about 0.3 square kilometer (79 acres; fig. 1). A small unnamed ephemeral stream is east of Fuels Area C, and Gateway Lake (not shown on figure) is northeast of the area. Prairie Ridge Golf Course is about 265 meters (m; 870 feet [ft]) east of Fuels Area C.