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1 <br />� CAMBRIA <br /> Quarterly Sampling <br /> Groundwater samples from all wells were analyzed for total purgeable hydrocarbons as <br /> gasoline (TPHg) by EPA Method 8015 (Modified), benzene, toluene, ethylbenzene, xylenes <br /> (BTEX), and methyl tertiary butyl ether (MTBE) by EPA Method 8020 Groundwater <br /> samples from wells MW-5, MW-8, RW-IA, the CalTrans well, and the domestic wells were <br /> also analyzed for fuel oxygenates (methyl tertiary butyl ether (MTBE), ethyl tertiary butyl <br /> ether (ETBE), di-isopropyl ether (DIPS), and tertiary amyl methyl ether (TAME)) and <br /> ethylene dibromide (EDB) by EPA Method 8260A Groundwater samples from wells MW-5, <br /> MW-8, and RW-IA were also analyzed for methanol by EPA 8015 (Modified) <br /> Field monitoring data and chemical analytical data are presented in a summary table in <br /> Blaine's groundwater monitoring report (Appendix A) Additional analytical data are <br /> summarized on Table 1 <br /> Conclusions and Recommendations <br /> The petroleum hydrocarbon and MTBE concentrations in groundwater samples collected <br /> from the shallow wells this quarter are within the historical norm for this site Wells MW-5, <br /> MW-8, and RW-IA continue to contain the highest levels of hydrocarbons and MTBE <br /> However, analytical data from offsite wells suggests the hydrocarbons and MTBE detected <br /> onsite wells (MW-5, MW-8, and RW-1A) are remaining onsite <br /> We are currently pursuing a sewer discharge permit from the local sewer district and planning <br /> to install a groundwater treatment system behind the service station Extracted groundwater <br /> from well RW-lA will be treated with activated carbon and then discharge to the sanitary <br /> sewer <br /> Groundwater samples from the Foster well contained 12 6 ppb MTBE by EPA Method 8260 <br /> This is the first confirmed detection of MTBE in this well This well is currently out of <br /> service and the Foster residence is hooked up to the city water supply Groundwater samples <br /> from the Sanelia well contained 1,370 ppb of TPHg This sample was collected using a bailer <br /> The sample collected from the sample port did not contain detectable levels of gasoline The <br /> Sanella residence is also hooked up to the city water supply and the well is only used for <br /> irrigation purposes TPHg has been detected in this well during previous sampling events <br /> Since none of the other wells located between the Foster well and the Sanella well and the <br />. Shell Service Station contain detectable levels of gasoline constituents, it is unlikely the <br /> 0783 3 <br />