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TABLE IV shows the results of water samples from MW-4. Except for the December, <br /> 1997 event, all compounds have been below detection limits. As discussed in the last <br /> report, it appears that samples taken from MW-3 & MW-4 were somehow mislabeled <br /> during processing. events since completion have all been below detection limits. However, <br /> the December,. The top of the well screen is at 5' below surface, which is above current <br /> groundwater depth. <br /> PLATES U through VI show the inferred lines of equal concentrations of BTEX& TPHg <br /> from the latest work There does not appear to be any significant change in the shape of the <br /> plume, indicating there is Iittle or no lateral movement. <br /> In March of this year, we discussed the project with another environmental firm, and asked <br /> them to make recommendations for cleaning up the site. After an intensive review, they felt <br /> that a modified "pump & treat" test would be the best way to determine cleanup options. <br /> However, the San Joaquin County EHD staff did not concur; they believed that air sparging <br /> was a better technique. It was pointed out that the groundwater was too shallow, and that <br /> there would not be sufficient vadose zone to allow air sparging to be effective. The County <br /> staff directed that quarterly monitoring continue pending further review and analysis. <br /> W continue to believe that further quarterly monitoring will not serve any useful purpose, <br /> and is not cost effective. Since the County staff did not approve what we believe to be a <br /> viable approach to reducing levels of contamination, we offer the following alternative: <br /> Install ORC socks in MW-2 and monitor the results.This is the only well which has shown <br /> high levels of petroleum compounds, and the water plume is of limited size and extent. <br /> Based upon work done on other sites, this is a relatively inexpensive method of reducing <br /> groundwater contamination to acceptable levels The owners have complied with all <br /> directives and requirements of the County EHD, RWQCB, and Cleanup Fund staffs. They <br /> are most anxious to obtain site closure so that they may sell the property. <br /> We would appreciate input from the County EHD staff so that we can proceed with <br /> whatever is r quired to obtain site closure <br /> W <br /> Wm u ter &As ciates ?ED GEO" <br /> cc: uis Lechich <br /> . . WQCB .. ffi Lb's A I HUNGER <br /> .cp Joc/r t 9y <br /> * NO.854 <br /> . of c�;a� <br /> 2 <br />