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Ms. Yvonne Miller 01 July 2009 <br /> A R and M E Glover Trs Page 2 of 2 <br /> Re: 7675 W. Eleventh Street <br /> depths as the observation DPE wells, 25 feet bsg; if a deeper well is required to <br /> accommodate the DPE system, the deeper interval should be continuously cored to <br /> identify and avoid any unrecognized sandy units that may contribute unimpacted, `clean' <br /> groundwater to that extracted, thereby decreasing system efficiency and increasing <br /> costs. <br /> • Fuel oxygenates and lead scavengers have not been detected in significant <br /> concentrations, or at all, to date; you may therefore drop them from the proposed <br /> analytical regimen. <br /> • The EHD approves testing of AS, but is. concerned that with depth to groundwater <br /> varying from approximately 6 to 9 feet bsg, the shallow fine-grained soil may inhibit or <br /> prevent the recovery of the sparged air; therefore the EHD will review the results of that <br /> test very carefully before approving its use on the site. <br /> • The EHD does not approve collecting and analyzing groundwater samples from all wells <br /> immediately prior to and following each pilot test as this is likely to be excessive — the <br /> more distal wells yielding groundwater that is. not impacted are not likely to yield different <br /> results; wells so sampled should be limited to those likely to exhibit significant results. <br /> • Preparation of an SCM.and CAP that incorporates the findings of this and previous <br /> investigations is approved. <br /> To comply with the State Water Resources Control Board. Resolution 2009-0042, the routine <br /> sampling of the wells on your site is reduced to the following: <br /> • Semi-annual —MW-2, MW-3 and MW-4. <br /> • Annual — MW-1, MW-5, MW-6, MW-7, MW-8. <br /> • As noted above, fuel oxygenates and lead scavengers have not been a significant <br /> contaminant on this site, and with the exception of methyl tert-butyl ether (MTBE), may <br /> be dropped from routine analysis of the groundwater samples. <br /> The newly installed monitoring well should be sampled quarterly until a concentration trend is <br /> established. <br /> Questions and comments may be addressed to Nuel Henderson at (209) 468-3436. <br /> Sincerely, <br /> aid <br /> Nuel C. Henderson, Jr., PG Margar6t Lagorio, REHS <br /> Engineering Geologist Program Coordinator <br /> Copy: James Barton, CVRWQCB, 11020 Sun Center Dr. #200, Rancho Cordova, CA <br /> 95670 <br /> Todd Hafner, ATC, 1117 Lone Pine Avenue, Ste B, Modesto, CA 96361 <br /> Work Plan Comment Letter 0709 <br />