ARCHIVED REPORTS_ENVIRONMENTAL SITE ASSESSMENT

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SECTION V. FINDINGS This Limited Phase II was performed in order to evaluate recognized environmental conditions (RECs) identified by review of documents provided to PEI and by PEI's Phase I ESA (July 2010). Laboratory data for this investigation are summarized below in the following Tables: Table 1 Soil Vapor VOC Results Table 2 Soil Matrix Samples from Vapor Locations—carbon chain analysis Table 3 Soil Matrix Samples from Vapor Locations - VOCs Table 4 Soil Matrix from Boring Locations—carbon chain analysis Table 5 Soil Matrix from Boring Location—VOCs Table 6 Soil Matrix Samples from Groundwater Locations—carbon chain analysis Table 7 Groundwater Samples—carbon chain analysis Table 8 Soil Matrix Samples from Groundwater Locations—VOCs Table 9 Groundwater Samples—VOCs Table 10 Select Samples for Pesticides, Herbicides, SVOCs, and Metals Most of the outdoor areas are covered with thick(6- to 8-inch) concrete, massively reinforced. Significant interior and exterior patching has also occurred with paving that is dissimilar (e.g., differing density) to the surrounding materials. In addition, clayey silt underlies the entire Site. These two factors severely limited the penetration of radar waves into the subsurface and provided some interference during the geophysical investigation. Despite these inhibitors, Sierra Nevada GSI located two septic systems adjacent to each other along the east side of the property. Sierra also marked the surface location of several apparent subsurface anomalies with spray paint. Four possible USTs (or graves) were marked (two at the southeast corner of the main building and two beneath the north parking area). Subsequent excavation showed the two anomalies at the southeast corner of the building were, in fact, UST graves (locations of removed USTs). The two anomalies in the north parking area were associated with unmarked utility piping (i.e., the fire suppression water line). Several planned boring locations were moved slightly to avoid subsurface obstructions. Based upon the scope of work performed and the data collected, PEI's findings can be summarized as follows: ♦ With regard to the soil vapor analyses, two areas of low-level impact by toluene and trichlorofluoromethane (Freon 11), were noted. (Figure 4) The toluene concentrations were well below California Human Health Screening Levels (CHHSLs) of 380 µg/L. The CHHSLs do not address Freon 11. The Freon 11 impact appears related to the vault/tunnel/drain system inside the main building, while the toluene impact is associated with the southeastern and southern portions of the property exterior to the building. ♦ An area of impact to the soil from the motor-oil range of petroleum hydrocarbons (C23 — C35) underlies the southeastern corner of the building, both underneath the building and outside (Figure 5). Inside the building, petroleum impacts above the general regulatory standard of 10,000 mg/kg (ppm) for C23-25 hydrocarbons (motor-oil range) appear to Limited Phase II Environmental Site Assessment Report Pinnacle Environmental,Inc. 248 Industrial Avenue,Stockton,CA 95206 Page 15