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it IA • CAMBRIA HYDROCARBON DISTRIBUTION IN GROUNDWATER TPHg and BTEX were not detected in the groundwater sample from boring SB-1 The groundwater sample contained 48,000 parts per billion (ppb) MTBE (detected by EPA Method 8260) and 220 ppb TAME No other fuel oxygenates or lead scavengers were detected in the groundwater sample Groundwater data are summarized in Table 3 and TPHg, benzene, and MTBE results are presented on Figure 2 The certified analytical report for the water sample is presented in Appendix C CONCLUSIONS Boring SB-1 was drilled in the vicinity of the northwestern dispenser island to assess the vertical extent of petroleum hydrocarbons and fuel oxygenates previously detected in soil Low concentrations of MTBE were detected in the soil at depths of 25, 30, 50, and 60 fbg Therefore, i the vertical extent of the MTBE detected in soil sample DP-4 is limited to soil shallower than 6 . fbg beneath the northwestern dispenser The groundwater sample collected from S13-1 contained 48,000 ppb MTBE and 220 ppb TAME, indicating that groundwater beneath the site has been impacted by fuel oxygenates Boring SB-2 was drilled north of the northeastern dispenser island area to assess the lateral extent of petroleum hydrocarbons and fuel oxygenates in soil No petroleum hydrocarbons or fuel oxygenates were detected in soil from SB-2, defining the lateral extent of impacted soil identified in sample DP-4 RECOMMENDATIONS The groundwater results from this investigation suggest that further investigation is warranted Cambria recommends installing monitoring wells to determine groundwater flow direction beneath the site and to monitor MTBE and fuel oxygenate concentrations in groundwater Cambria also recommends completing a receptor survey to identify water-producing wells and surface water bodies within a 2,000-foot radius from the subject site If SJCPHS/EHD concurs with these recommendations, Cambria will prepare a work plan i i 0953 4