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1 <br /> 53 POTENTIAL EXPOSURE PATHWAYS AND RECEPTORS <br /> Potential exposure pathways and receptors (exposure scenarios) were evaluated based on the <br /> ' previously defined sources of chemicals, affected media, transport mechanisms, and land use at <br /> and in the vicinity of the site Specifically, identification of complete exposure pathways was <br /> based on the presence of <br /> ' 1) a source and mechanism of chemical release, <br /> 2) one or more retention or transport media (e g , soil, groundwater, or air), <br /> ' 3) a point of potential contact with the impacted medium,, and <br /> 4) an exposure route at the point of contact (e g , inhalation, ingestion, or dermal contact) <br /> ' 5.3 1 Onsite Receptors <br /> Based on the presence of a paved surface and the estimated depth of impacted soils (16 to 35 feet <br /> bgs) at the site, daily site occupants will not be subject to direct exposure (ingestion, dermal <br /> contact) to hydrocarbons in site soils However, as a result of potential cracks in the paved <br /> ' ground surface and/or the building foundation at the site, potential exposure of site occupants to <br /> hydrocarbons in soil may occur through volatilization and emission of vapors to outdoor and <br /> indoor air <br /> ' Based on the depth to groundwater (23 to 48 feet bgs) and the absence of onsite water supply <br /> wells, there is no potential for direct contact with groundwater at the site The sole potential <br /> exposure of site occupants to chemicals in groundwater is through inhalation of volatile <br /> emissions to outdoor and indoor air Completeness of this exposure scenario is once again based <br /> on the conservative assumption that cracks may occur in the paved surface and/or the building <br /> foundation at the site <br /> As a result of hydrocarbon source removal from soils, the potential for future leaching of <br /> chemicals in soils to groundwater is considered negligible This is corroborated by the sporadic <br /> ' detection and stability of hydrocarbon concentrations in groundwater underlying the site As a <br /> result, exposure pathways associated with future leaching of soils to groundwater are considered <br /> ' incomplete <br /> Although unforeseen, potential construction or maintenance/utility work may occur at the site <br /> ' Should excavation occur to depths below 16 feet bgs, such activities may result in temporary, <br /> direct exposure (ingestion, dermal contact, inhalation of volatiles and particulates) of workers to <br /> hydrocarbons in soils underlying the site Excavation is not likely to occur to depths below the <br /> ' water table, particularly in the absence of dewatering, hence, direct exposure of construction <br /> workers to groundwater was considered an incomplete pathway <br /> ' Based on the above-mentioned potential complete exposure pathways, the following exposure <br /> scenarios associated with onsite human receptors are considered complete and were evaluated in <br /> the R13CA analysis <br /> • Inhalation of volatiles from soil to outdoor air (onsite commercial/industrial receptor), <br /> F1Pro�eet5��01375MIasmr14Vp1Ciosuie 11=0137cnext do 14 <br />