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.1 <br /> Mr Martin Harms <br /> Page 3 of 3 <br /> gg/L in wells MW4, MW6 or MW7 No other oxygenated gasoline additives or lead scavengers were <br /> detected in any site well Analytical results are summarized in Table 2 The estimated extent of <br /> dissolved MTBE contamination based upon the most recent analytical results is presented on Figure 3 <br /> Attachment B contains the laboratory report and chain of custody documentation Charts showing <br /> contaminant concentration trends are included in Attachment C <br /> SUMMARY AND CONCLUSIONS <br /> Shallow groundwater beneath the site rose an average of 0 47 feet between September 29, 2004 and <br /> December 10, 2004 Groundwater on December 10, 2004 generally flowed to the northwest at a <br /> relatively flat gradient of approximately 5 ft/mile <br /> TPHg was detected only in well MW2, at 88 gg/L No benzene,toluene, or xylenes were detected in any <br /> site well, and ethylbenzene was detected only in well MW 1, at 0 9 µg/L MTBE was detected in wells <br /> MW 1, MW2, MW3, and MW5 at levels ranging from 1 9 to 4 9 gg/L No well contained MTBE at <br /> concentrations exceeding either the primary Maximum Contaminant Level (MCL) of 13 gg/L, or the <br /> secondary MCL of 5 0 gg/L <br /> Based upon the most recent analytical results, we have estimated that less than one tablespoon of <br /> dissolved MTBE remains in the shallow aquifer beneath the site(Attachment D) <br /> A copy of this report should be forwarded to Ms Lori Duncan of EHD and Mr James L L Barton of the <br /> I California Regional Water Quality Control Board, Central Valley Region (RWQCB) <br /> Please feel free to contact Ground Zero at (209) 838-9888 should you have any questions regarding this <br /> submittal <br /> Respectfully, <br /> Ground Zero Analysis, Inc <br /> Joseph L Vasquez ¢ JOHN a <br /> Staff Geologist No L,69 <br /> NS <br /> John P Lane <br /> CA Registered Geologist No 6795 <br /> Attachments <br /> G1GROUNDZEI'ruftBoy\Rcports\QMRU00414QM2004 doc <br />