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Human Health Screening Evaluation <br /> Former Vernalis Pump Station September 2,2010 <br /> SAIC-Benham quantitatively evaluate the exposure routes of incidental ingestion of soil and <br /> dermal contact with soil, inhalation of wind-blown dust for non-volatile constituents, and <br /> inhalation of chemical vapors from soils for volatile constituents. <br /> 3. CONSTITUENTS OF POTENTIAL CONCERN AND <br /> EXPOSURE CONCENTRATIONS <br /> The COPCs for the site were identified during the site characterization process. SAIC-Benham <br /> utilized soil analytical data collected between 0 and 10 feet bgs during previous site <br /> investigations to evaluate exposure (Tables 1 and 2). <br /> Samples of soils potentially affected by historic crude-oil pipeline operations at the site were <br /> previously collected and analyzed for critical hydrocarbon constituents of crude oil identified in <br /> the PEA Guidance Manual. <br /> The site characterization studies conducted to date indicate that the on-site soils are affected by <br /> total petroleum hydrocarbons (TPH) and low levels of toluene, ethylbenzene, total xylenes, and <br /> PAHs. The areas of crude-oil affected soil and groundwater are depicted on Figure 2. The <br /> analytical results of site-related soil and groundwater investigations conducted by Radian <br /> International, Inc. (Radian), Geomatrix, and SAIC are provided as Appendices C.1 through C.5. <br /> All analytes detected in at least one sample between 0 and 10 feet bgs are considered COPCs. <br /> Benzene and the PAHs acenaphthylene and anthracene were not detected in any soil samples; <br /> therefore, those constituents are not considered COPCs. The crude-oil based COPCs for on-site <br /> soils are toluene, ethylbenzene, total xylenes, and PAHs (Table 2), which are discussed further in <br /> the following sections. <br /> 3.1 ON-SITE SOIL IMPACTS AND EXPOSURE CONCENTRATIONS <br /> Impacts to on-site soils have been characterized with regulatory oversight provided by the <br /> Central Valley RWQCB. Most investigations specifically included the collection of on-site soil <br /> samples to support the development of an HHSE, and data of adequate analytical quality (e.g., <br /> low detection limits)were collected to support this HHSE. SAIC-Benham used data from site <br /> characterization studies conducted in 1998, 2002, 2003, 2005, and 2008 in preparing this HHSE. <br /> A total of 67 soil samples were collected from 33 soil borings from 0 to 10 feet bgs at the site. <br /> SAIC-Benham used soil sample analytical results to evaluate risks and hazards in this HHSE, <br /> which was performed after the Central Valley RWQCB was satisfied that the site had been <br /> adequately characterized, and noted that a final determination for the site could not be made until <br /> an HHSE was completed(Central Valley RWQCB, 2008). A summary of the analytical results <br /> for COPCs for soil samples collected between 0 and 10 feet bgs for investigations conducted by <br /> SAIC, Geomatrix, and Radian are provided in Tables 1 and 2. <br /> The Central Valley RWQCB is satisfied that the site soil characterization dataset adequately <br /> describes site conditions; therefore, SAIC-Benham calculated exposure point concentrations <br /> (EPCs) as the upper confidence limit(UCL) of the mean soil concentration. SAIC-Benham used <br /> an EPA statistical software program, ProUCL Version 4.00.04 (EPA, 2009), to analyze the <br /> datasets provided in Tables 1 and 2. Most COPCs had high occurrences of non-detect results. <br /> ff� <br /> 4 1 iC The Benham Companies,LLC <br /> St j`® A Wholly Owned Subsidiary <br /> From&mxe to Solorhms <br />