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1 1 <br /> C A M B R I A <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 <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-lA 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-IA) is remaining onsite <br /> Groundwater samples from the CalTrans irrigation well and the private water wells did not <br /> contain TPHg, benzene, or fuel oxygenates this quarter with the exception of the Warman <br /> well as discussed above We will continue quarterly groundwater sampling and analysis to <br /> confirm the presence or absence of MTBE in these wells <br /> Methanol was not detected in wells MW-2 through MW-4, MW-6, MW-7, and MW-9 <br /> through MW-14 this quarter and has not been detected in these wells since sampling was <br /> initiated (September or December 1997) Oxygenates other than MTBE were not detected in <br /> wells MW-2 through MW-4, MW-6, and MW-12 through MW-14 this quarter and have not <br /> been detected in these wells since sampling began, with the exception of one ethanol <br /> detection to MW-12 during December 1997 <br /> Recommendations <br /> As discussed in our third quarter 1999 monitoring report, Cambria recommends that <br /> methanol analysis be discontinued in wells MW-2 through MW-4, MW-6, MW-7, and MW-9 <br /> through MW-14 since methanol has not been detected in these wells since sampling was <br /> initiated We also recommend discontinuing fuel oxygenate analysis in wells MW-2 through <br /> MW-4, MW-6, and MW-12 through MW-14 since oxygenates have not been detected since <br /> sampling began (with one exception, mentioned above) We will continue to analyze for <br /> MTBE by EPA Method 8020 Cambria will implement these changes during the first quarter <br /> 2000 sampling event unless we are notified otherwise by your office <br /> Cambria will continue to monitor the groundwater analytical data from the monitoring wells <br /> at this site to determine if additional plume delineation is necessary If additional <br /> investigative work is warranted in the future, we will make recommendations for this work <br /> 241-0783 3 <br />