Laserfiche WebLink
i <br /> = � As previously stated, the naphthalene applied action level (AAL) developed <br /> • by the California Department of Health Services {CDOHS} is the most stringent <br /> criterion that is applicable to substances identified on the former AFPC <br /> site. Therefore, the AAL for naphthalene should be used to assess acceptable <br /> site impacts on ground- 'and surface waters near the site. However, because <br /> the extent of diesel migration has been estimated in the remedial <br /> investigations using TPH analysis, cleanup levels will be discussed in terms <br /> of TPH diesel. Thus, acceptable soil naphthalene concentrations will be t' <br /> developed and used to calculate acceptable soil TPH concentrations. <br /> 4.3 Identification of Potential Exvosure Pathways <br /> Environmental and human health risks from underground fuel tanks leaks can <br /> only occur if there is a significant exposure pathway. The possible exposure <br /> pathways are: <br /> • volatilization to the air followed by inhalation <br /> • leaching to groundwater <br /> • fugitive dust erosion,. suspension and inhalation <br /> • surface runoff to off-site receptors <br /> li <br /> The significance of these pathways is determined by the mobility of <br /> on-site species, land-use, and presence of institutional controls. . <br /> Volatilization occurs from spills of substances with substantially smaller <br /> molecular weight than the components of diesel. A typical case involves <br /> buildings constructed over locations of unknown gasoline spills that have had <br /> gasoline fume intrusion through cracks in slabs. Additionally, the spill is <br /> t <br /> located beneath ten feet of moist, clayey soils that would inhibit diffusive <br /> transport of any volatilization that did occur. Based on these observations, <br /> 4 this transport pathway is not applicable for the substances encountered at <br /> this site. <br /> 4-4 <br /> GGA/0179b <br /> l <br />