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✓i% Geomatrix <br /> 1 <br /> . 20 Additional Comments. Additional information to support the NFAR request for <br />' this Site is provided in the following Section 3 0 <br /> 3.0 CONFORMANCE TO CRITERIA FOR LOW-RISK GROUNDWATER CASE <br />' The RWQCB staff considers several factors when evaluating conformance to low-risk <br /> groundwater cases (TRR—Appendix A) These factors are discussed in the following two <br />' sections <br />' 3.1 NFAR CRITERIA FOR CASES ABOVE BACKGROUND GROUNDWATER <br /> CONDITIONS <br />' The six criteria for low-risk groundwater cases (Section 6 4 of the TRR [CVRWQCB, 2004]) <br /> are discussed as follows <br /> 1 The source of the UST release has been identified and removed. The release <br /> was identified in 1988 and the USTs were removed Approximately 180 cubic <br /> yards of affected soil were excavated down to 1 i feet bgs and removed from the <br />' Site <br /> 2 Free-phase product in groundwater has been removed. No separate-phase <br />�• petroleum product has been observed in the groundwater monitoring wells at the <br /> Site <br /> 3 Contaminants remaining in the vadose zone cannot migrate in soil vapor or <br /> leach at concentrations that would cause groundwater to exceed WQOs. <br /> Affected soil was excavated down to about 11 feet bgs in 1988 during the removal <br />' of the former USTs Field screening results of soil samples collected from the <br /> bonngs at the Site during previous investigations do not indicate the presence of <br /> significant mass of residual petroleum hydrocarbons in soil shallower than <br />' approximately 16 feet bgs (below typical static groundwater level) at the Site <br /> (Figures 3 and 4) <br />' Because the release occurred at least 18 years ago, residual petroleum hydrocarbons <br /> currently remaining in the vadose zone at the Site, if any, are believed to have <br /> reached equilibrium The residual petroleum hydrocarbons remaining at the Site are <br />' not expected to cause groundwater outside of the current extent of the plume to <br /> exceed WQOs See Section 3 2 1 for additional discussions <br />' 4 No receptors are threatened by the remaining contaminants in soil or <br /> groundwater. No receptors have been identified in the area of the Site See <br /> Section 3 2 1 and Discussion No 16 in Section 2 0 <br />' 5 Pollutants remaining in groundwater do not create or threaten to create risk to <br /> human health and safety or to anticipated future beneficial use(s) of shallow <br />' groundwater. Residual petroleum hydrocarbons remaining at the Site are not <br />' 1 16000916437 0001Archtve16437 041 doc 7 <br />