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ENVIRONMENTAL HEALTH DEPARTMENT <br /> Po�,N SAN JOAQUIN COUNTY Unit Supervisors <br /> Carl Bergman,R.E.H.S. <br /> Donna DK.Heran R.E.H.S. <br /> .� 304 East Weber Avenue, Third Floor <br /> Director Mike Huggins,R.E.H.S,R.D.I. <br /> ` �- At Olsen,R.E.H.S. StOCktOn, California 95202-2708 Douglas W.Wilson,R.E.H.S: <br /> • �., � ,,;P• Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> 4Ci F O R� Robert S. <br /> Laurie A.Cotulla,R.E.H.S. Fax: (209) 464-0138 M ,R.E.H. <br /> Program Manager Mark Barcellloncellos,R.E.H.S.. <br /> KAREN PETRYNA 'JAN 0 7 2004 <br /> EQU2V/3- LLC <br /> PO BOX 7869 <br /> BURBANK CA 915@Q,-7869 <br /> RE: Former Texaco Station SITE CODE: 1055 <br /> 440 Charter Way <br /> Stockton CA 95206 <br /> San Joaquin County Environmental Health Department(SJC/EHD) has reviewed <br /> "Groundwater Monitoring Report—Third Quarter 2003 and Groundwater Analytical <br /> Reduction Request' dated December 19, 2003 that was submitted on your behalf by <br /> Cambria Environmental Technology, Inc. (Cambria) and has the following comments. <br /> The report documents a routine quarterly groundwater monitoring and sampling event <br /> performed on August 14, 2003. In the report Cambria recommends eliminating the fuel <br /> oxygenates di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE) and tertiary amyl <br /> methyl ether, and fuel additives 1,2-dichloroethane (1,2-DCA) and ethylene dibromide <br /> (EDB) from the routine analyses suite. The request for this reduction is based on the <br /> historical lack of detections of these compounds in most of the wells sampled. Analysis <br /> for methyl tertiary butyl ether(MtBE) and tertiary butyl alcohol (TBA)will continue on a <br /> quarterly schedule. <br /> SJC/EHD can approve discontinuing analyses for DIPE, ETBE and TAME. Analysis for <br /> 1,2-DCA and EDB must continue. The reporting limits for these two constituents have <br /> routinely been high, above the accepted maximum contaminant level (MCL) of 0.5 <br /> micrograms per liter for 1,2-DCA. If a historical trend of non-detects can be established <br /> for 1,2-DCA and EDB at acceptable reporting or detection limits, they can be considered <br /> for removal from the required analytical suite. <br /> Five quarters of groundwater monitoring and sampling have been performed on the <br /> deeper screened wells at this site. Predominant groundwater flow direction in the <br /> deeper zones has been reported by Cambria as being towards the south or southeast. <br /> Downward vertical gradient has also been reported (Site Investigation Report, <br /> October 25, 2002, Conclusions). Analytical results indicate that the vertical and lateral <br /> extents of the groundwater contamination at depth have not been defined. Submit a <br /> work plan to continue the investigation of impacted groundwater. In addition, continue <br /> evaluation of the reported downward vertical gradient. This should be done in each <br /> quarterly report. The work plan is due no later than February 27, 2004. Along with the <br /> work plan submit a Site Conceptual Model for the site, including detailed maps, cross- <br /> sectional diagrams and a narrative description describing controls on contaminant <br /> distribution, migration mechanisms, pathways and rates, plume disposition over time and <br /> sorbed and dissolved contaminant masses. <br />