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Phase 11 Additional Subsurface Investigation <br /> Tracy Comers Shopping Center <br /> 3225 North Tracy Boulevard <br /> Tracy,California 95376 <br /> Partner Project Number 14-129814.3 <br /> January 27,2015 <br /> Page 16 <br /> standards. Cleanup levels ultimately dependent on site-specific factors and are established by the <br /> regulatory agencies on a case-by-case basis. <br /> Environmental Screening Levels <br /> Soils were compared to the Environmental Screening Levels (ESLs) established by the San Francisco Bay <br /> Regional Water Quality Control Board (SFBRWQCB) as an initial screening level evaluation. ESLs aid in <br /> assessing the potential threats to human health, terrestrial/aquatic habitats, and/or drinking water <br /> resources due to contaminants in soil, soil gas, and/or groundwater. Under most circumstances, the <br /> presence of contamination below applicable ESLs can be assumed to not pose a significant, chronic (i.e., <br /> long-term) adverse risk to the applicable receptor of concern. Conversely, sites that exceed ESLs generally <br /> require further evaluation and/or remediation. Please note that the ESLs were developed using default <br /> assumptions (e.g., standard exposure factors) and, consequently, are only meant for screening level <br /> assessments. The ESLs should not be considered enforceable regulatory standards. Cleanup levels <br /> ultimately dependent on site-specific factors and are established by the regulatory agencies on a case-by- <br /> case basis. <br /> Laboratory Analysis Results <br /> SunStar reported the laboratory analysis results on January 21, 2015. Refer to Table 2 for a summary of <br /> the soil sample PCE and daughter compounds laboratory analysis results. Refer to Table 3 for a summary <br /> of the groundwater sample PCE and daughter compounds laboratory analysis results. <br /> Refer to Appendix C for the full laboratory analysis report,which includes chain-of-custody and laboratory <br /> quality assurance/quality control (QA/QC) documentation. Laboratory QA/QC data were within <br /> acceptable limits. <br /> Soil Sample Analytical Results <br /> None of the analyzed soil samples contained concentrations of PCE or daughter compounds above <br /> laboratory practical quantitation limits(PQLs). <br /> Groundwater Sample Analytical Results <br /> As shown in Table 3, groundwater samples B2-GW, B3-GW, and B4-GW contained detectable <br /> concentrations of PCE. PCE was detected in groundwater samples B2-GW, B3-GW, and B4-GW at <br /> concentrations of 2.8 micrograms per liter(pg/L), 30 pg/L,and 8.8 pg/L, respectively. <br /> Discussion <br /> No soil samples contained concentrations of PCE or daughter compounds above laboratory PQLs. The <br /> laboratory PQLs did not exceed the ESLs. <br /> Groundwater samples B3-GW and B4-GW contained detectable concentrations of PCE at 30 pg/L and 8.8 <br /> pg/L, respectively,which is in excess of the WQG of 5 pg/L for PCE. Groundwater sample B2-GW detected <br /> PCE at a concentration of 2.8 pg/L,which is below the WQG of 5 pg/L for PCE. <br /> PARTNER <br />