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Project No. 014-13157 Page No. 3 APPLICABLE REGULATORY AGENCY REFERENCE Krazan's evaluation of the results and findings associated with the sampling included referencing the Interim Final 2007 (Revised December 2013) San Francisco Regional Water Quality Control Board's (SFRWQCB) environmental screening levels (ESLs) referenced in the technical document titled, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater. According to the RWQCB's 2013 documents, ESLs are considered to be conservative. Under most circumstances and within limits described by the RWQCB, the presence of a chemical in soil, soil-vapor, or groundwater at concentrations below the corresponding ESL can be assumed not to pose a significant, long-term (chronic) threat to human health and the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. Active remediation may or may not be required, however, depending on site-specific conditions and considerations. As stated by the RWQCB, the ESL document may be especially beneficial for use at sites with limited impacts, where the preparation of a formal environmental assessment may not be warranted or feasible due to time and cost constraints. It should be noted, ESLs are intended for use only at sites overseen by the RWQCB. For the purposes of evaluating specific COCs, Krazan also referred to the September 2009 and November 2009 (ethylbenzene only) technical documents prepared by the California Environmental Protection Agency (Cal/EPA) titled Use of California Human Health Screening Levels in Evaluation of Contaminated Properties. The California Human Health Screening Levels (CHHSLs) are concentrations of 54 hazardous chemicals in soil, shallow soil gas, and indoor air that the Cal/EPA considers to be below thresholds of concern for risks to human health. The CHHSLs were developed by the Office of Environmental Health Hazard Assessment (OEHHA) on behalf of Cal/EPA, and are contained in a Cal/EPA report titled Human- Exposure-Based Screening Numbers Developed to Aid Estimation of Cleanup Costs for Contaminated Soil. The thresholds of concern used to develop the CHHSLs are an excess lifetime cancer risk of one-in-a- million (104) and a hazard quotient of 1.0 for non-cancer health effects. The CHHSLs were developed using standard exposure assumptions and chemical toxicity values published by the U.S. EPA and Cal/EPA. CHHSLs can be used to screen sites for potential human health concerns where releases of hazardous chemicals to soils have occurred. Under most circumstances, and within the limitations described in the January 2009 documents, the presence of a chemical in soil, shallow soil vapor, and/or indoor air at concentrations below the corresponding CHHSLs can be assumed to not pose a significant health risk to people who may live (Residential CHHSLs) or work (Commercial/Industrial CHHSLs) at the site. It should be noted, CHHSLs are not regulatory "cleanup standards" and regulatory agencies cannot be compelled to use the CHHSLs as final cleanup standards for a contaminated property. REPORT OF FINDINGS The analytical results were not detected (ND) for TPH-d and TPH-mo for the six (6) confirmation soil samples, EX-1 through EX-6 as shown on Table I. The laboratory analytical results are provided in Appendix C. The results of the compaction testing conducted on the backfill material are provided in Appendix D. The soil from the excavation was removed and transported to Forward Landfill of Manteca, California. KRAZAN & ASSOCIATES, INC. With Offices Serving the Western United States Phase II LSA - 014-13157 Excavation Report FINAL docx