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Human Health Screening Evaluation <br /> US Can—Welty Road March 19,2012 <br /> investigation process; Appendix Q. However, they do exceed State of California and federal <br /> TDS standards for drinking water as well as agricultural-use criteria. Therefore, shallow <br /> groundwater at the Site is not likely to be used as a drinking-water source. Ingestion of <br /> groundwater was considered an incomplete exposure route and was not evaluated quantitatively <br /> for this reason. <br /> 2.3 SOIL VAPOR <br /> Vapor intrusion of volatile organic compounds(VOCs) to indoor air in a residential scenario is a <br /> potentially complete exposure pathway. VOCs were detected in groundwater samples (Tables 4 <br /> and 5), and the data from these borings were utilized to quantitatively evaluate risk to human <br /> health from vapor intrusion of VOCs to indoor air. <br /> 2.4 SUMMARY <br /> SAIC quantitatively evaluated the exposure routes of incidental ingestion of soil and dermal <br /> contact with soil; inhalation of wind-blown dust for non-volatile constituents; inhalation of <br /> chemical vapors from soils for volatile constituents; and inhalation of chemical vapors from I <br /> subsurface vapor intrusion to indoor air for volatile constituents detected in groundwater <br /> (Figure 3). <br /> 3. CONSTITUENTS OF POTENTIAL CONCERN AND <br /> EXPOSURE CONCENTRATIONS <br /> SAIC identified COPCs for the Site from site investigations conducted by SAIC and others from I <br /> 1995 through 2010. SAIC and others collected and analyzed samples of soil and groundwater <br /> potentially affected by historical crude-oil pipeline operations for hydrocarbon constituents of <br /> crude oil identified in the PEA Guidance Manual and the Vapor Intrusion Guidance. Several of I <br /> the investigations specifically included the collection of soil and groundwater samples to support <br /> the development of this HHSE. Data of adequate analytical quality(e.g., low detection limits) <br /> were collected to support this HHSE. All analytes detected in at least one sample in a given data <br /> set are considered COPCs. It should be noted that metals are not typically considered critical <br /> constituents of crude oil at HPP-BTR sites (Appendix D); therefore, samples were not analyzed <br /> for metals at the Site. Soil and groundwater analytical data from the site investigations are <br /> included as Appendix C. <br /> 3.1 ON-SITE SOIL IMPACTS AND EXPOSURE CONCENTRATIONS <br /> SAIC and others conducted site investigations that indicate the Site soil is affected by total <br /> petroleum hydrocarbons (TPH),benzene, toluene, ethylbenzene, and xylenes (BTEX), and <br /> polynuclear aromatic hydrocarbons (PAHs). The area of crude-oil affected soil is depicted on <br /> Figure 2. A total of 77 soil samples from 55 locations were collected from 0 to 10 feet bgs, and <br /> used to evaluate risks and hazards from exposure to COPCs in soil. SAIC performed this HHSE I <br /> after the Central Valley RWQCB was satisfied that the Site had been adequately characterized <br /> (Central Valley RWQCB, 2011). A summary of the analytical results for BTEX and PAHs for <br /> soil samples collected from 0 to 10 feet bgs are provided in Tables 1 and 2, respectively. <br /> 4 <br /> SAIE <br /> I <br />