Laserfiche WebLink
P A G E 6 <br /> I� <br /> 1 Summary of Realistic Exposure Pathways <br /> In summary, the following exposure pathways were selected for <br /> evaluation in the HRA: <br /> !f <br /> Medium Scenario Exposure Route <br /> I I <br /> Soil Construction Incidental ingestion <br /> Dermal contact ,# <br /> Inhalation of vapors(VOCs only) <br /> 3 <br /> Ground water Industrial Inhalation of vapors(VOCs only) <br /> Ground water Construction Inhalation of vapors'(VOCs only) <br /> i <br /> i; <br /> DEVELOPMENT OF SITE-SPECIFIC SCREENING LEVELS <br /> Based on the realistic exposure pathways identified in the'preceding <br /> j section, three sets of risk-based screening levels were developed, as <br /> follows: <br /> • Risk-based screening levels for soil, based on a construction;�scenario. <br /> • Risk-based screening levels for ground water, based on an industrial <br /> scenario. <br /> • Risk-based screening levels for ground water, based on a construction <br /> scenario. ;I <br /> Table 1 presents the risk-based screening levels for soil. These calculated <br /> levels were developed in accordance with guidance issued by USEPA <br /> (1996), USEPA Region 9 (1999), and ASTM (1996), and incorporate current. <br /> toxicity information published by California EPA and USEPA. 'Exposure <br /> assumptions are based on default values recommended by USEPA in all <br /> cases, except with regard to exposure frequency and exposure duration. <br /> Default values are not available for these parameters under a construction <br /> scenario, and so site-specific assumptions were made regarding,exposure <br /> frequency and exposure duration. In light of the limited area of impact, <br /> any construction or excavation activity is expected to be limited in <br /> e <br />