11.3 Operable Unit 1 Hillside at Hill Air Force Base, Utah
Contact: Barrie Selcoe
Organization: CH2M
Email: [email protected]
11.3.1 Site Description and Conceptual Site Model
The subject site is Site 2 on a hillside adjacent to Operable Unit (OU) 1 at Hill Air Force Base. Figure 11-5 is the site map for the Operable Unit 1.
Figure 11‑5. Hill Air Force Base Operable Unit 1 site map.
Source: (CH2M 2011). Supplemental Human Health Risk Assessment Report for the Operable Unit 1 Hillside. Hill Air Force Base, Utah. December.
OU 1 contaminant sources consisted of pits and landfills where solvents and other chemicals were managed historically. Although arsenic wastes were not specifically managed at OU 1, it is suspected that geochemically reduced groundwater conditions, exacerbated by disposal of wastes in the OU 1 landfills, mobilized arsenic occurring naturally in the subsurface soil. The arsenic was then deposited on the hillside when groundwater emanated from historically flowing seeps and springs and contacted air. Currently, the arsenic-impacted soil appears as stained surface soil along the steep hill slope. Because the springs no longer flow, the contaminated spring “sediments” are currently more like surface soil than subaqueous sediment from the perspective of environmental fate and transport and potential human exposure. These “sediments” are therefore referred to as soil.
11.3.2 Sample Collection Strategy
11.3.3 Soil Type
11.3.4 Land Use/ Exposure Scenarios
11.3.5 In Vitro Bioavailability Analysis
11.3.6 Summary and Site Decision