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N%� <br /> 334 East Main Street <br /> Page 2 of 2 <br /> EHD approves of the tracer test concept involving the installation of approximately eight probes in <br /> the present underground'storage tank (UST) area, and approximately eight probes along the piping <br /> runs prior to the injection of chemical tracers to identify potential leak sources. However, prior to <br /> final approval and initiation of the fieldwork, please provide EHD with a map showing specific <br /> locations and depths for each probe along with the technical justifications for these locations. Also <br /> provide information concerning the UST-specific tracers to be used for this leak test, and specifics <br /> concerning the method for sampling and analyzing soil vapor samples collected from the soil vapor <br /> probes. EHD recommends that the soil vapor samples be collected in summa canisters, and, in <br /> addition to the tracers, that the samples be analyzed for total petroleum hydrocarbons as gasoline <br /> (TPH-g); benzene, toluene, ethyl benzene, total xylenes, (BTEX); methanol, ethanol, MTBE, ethyl <br /> tertiary butyl ether (ETRE), tertiary amyl methyl ether (TAME), di-isopropyl ether (DIPE), tertiary <br /> butyl alcohol (TBA), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB), using air <br /> methods instead of water/soil methods to analyze the vapor samples. <br /> EHD comments on the work plan dated January 19,2005,as follows: <br /> Secor proposes to advance six Geoprobe borings to the depth where groundwater is first encountered, <br /> approximately 33 feet bgs, to assess for residual non-aqueous phase liquid (NAPL) source. Although <br /> free product may be present, EHD does not see any indication of this when reviewing gasoline and <br /> BTEX results for the quarterly groundwater monitoring events. EHD will delay commenting on this <br /> proposal until after results are provided from the leak test. <br /> The last batch extraction report submitted to EHD was dated May 12, 2004, for the batch extraction <br /> events occurring weekly at this site. By letter dated October 16, 2003, EHD requested that monthly <br /> reports be submitted. Please submit batch extraction reports to EHD each month that include: <br /> • Gallonage of water extracted <br /> • Average MTBE concentrations <br /> • MTBE mass removed,and <br /> • Total MTBE mass removed to date. <br /> Also, include a discussion of the hydraulic control exerted by the weekly extraction events on plume <br /> migration in the quarterly groundwater monitoring reports. <br /> If you have any questions regarding this letter, please contact Vicki McCartney at (209)468-3456, <br /> or by electronic mail at vmccartney@sjcehd.com. <br /> Donna Heran, REHS,Director <br /> Environmental Health Department <br /> Victoria L. McCartney, Senior REHS Nuel C. Henderson,Jr., PG <br /> Unit IV-Site Mitigation Unit IV-Site Mitigation <br /> c: David Evans-Secor <br /> James L.L.Barton,PG-CVRWQCB <br />