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Leaching occurs when water infiltration carries contaminants to the <br /> groundwater beneath the site. Factors that influence leaching potential at <br /> the site are amount of water available for infiltration, soil permeability, <br /> land use, surfacing or paving, organic carbon content of soils, leachate <br /> solubility, and depth to groundwater. This is expected to be the main <br /> contaminant transport pathway for this site. <br /> Fugitive dust inhalation is a pathway not directly applicable at this <br /> site. If contamination is at the surface of a site, then the substances may <br /> be transported as windblown dust. As previously mentioned, the contamination <br /> at the site is ten feet below the surface and, therefore, is not susceptible <br /> to dust resuspension. For the same reason, the substances on-site are not <br /> available for surface water transport or direct human-soil contact. <br /> 4.4 Identification of Potential Receptors <br /> Once the potential transport pathways have been found, the receptors that <br /> may be exposed to those pathways must be identified. The groundwater <br /> transport and exposure pathway was isolated as the sole significant exposure <br /> pathway for the substances at the former AFPC Stockton site. A search was <br /> performed to identify local groundwater uses and locate nearby groundwater <br /> users. Based on a review of available records, the nearest downgradient or <br /> cross-gradient wells identified as sources of drinking water are the Cal Water <br /> Service Well 77-01, located just north of the site property approximately 3000 <br /> feet north of the maintenance shop, and the City of Stockton Oak Park West <br /> Well located in a city park approximately 4000 feet northwest of the <br /> maintenance shop (see Figure 5). The total depth of the Cal Water Service <br /> Well 77-01 is 500 feet, and the shallowest perforations are 200 feet beneath <br /> the surface. The City of Stockton Oak Part West well is 264 feet deep and <br /> perforated from 199 to 264 feet. Both wells service public water supplies and <br /> are the closest down- and cross-gradient wells in the area. These wells were <br /> chosen as the closest receptors because of existing institutional controls by <br /> the City of Stockton. New well installations are not expected to be <br /> perforated above 100 feet. Additionally, there is low potential for new wells <br /> 4-5 <br /> GGA/0179b <br />