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I <br /> WATT ERWORk CORR ----- -- <br /> A RESNA Comp•,y <br /> Envi►orunenta!Solufiunr <br /> -- <br /> Through Applied Science, <br /> Engineering&Construction <br /> 1710 Main Street <br /> Escalon, CA 95320 <br /> Phone: (209) 838-3507 ~_" November 8, 1991 <br /> Fax: (209) 838-3509 <br /> Ms. Laurie A. Cotulla <br /> Ii San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P.D. Box 2009 <br /> Stockton, CA 95201 <br /> Re: 1991 Fourth Quarter Groundwater Monitoring Report, Genstar Western Stone <br /> site, 8181 E. filth S�., Tracy, CA (cour_ty site code: 1393) <br /> Dear Ms. Cotulla: <br /> This letter presents the results of RESNAIWaterWork Corp.'s 1991 fourth Quarter groundwater s <br /> monitoring and sampling at the referenced site. Activities during the quarter included <br /> monitoring depth to groundwater, purging of wells, groundwater sampling, and analysis of <br /> samples for total petroleum hydrocarbons as diesel(TPHD),benzene, toluene,ethylbenzene,and <br /> xvlenes 'BTEX). <br /> - Groundwater monitoring and sampling was conducted on October 7, 1991. Depth to <br /> groundwater was measured in each well and subtract:d from wellhead elevation to determine <br /> groundwater elevation (Table 1). Water levels in October were found to have decreased <br /> approximately 1.75 feet since last measured in July 1991. Figure 2 depicts the groundwater <br /> gradient on October 7, 1991. <br /> Gradient magnitude and groundwater flow direction were slightly changed s>nee ugly: 1991, at <br /> appr4xtrnately.0;004 ft/ft or.21 ft/mile-in a north-northwesterly ditecti h <br /> Water samples were collected from each well on October 7, 1991, after purging and stabilization <br /> of pH, conductivity, and temperature. Mary Meays of the San Joaquin County Public Health <br /> Department was present to witness the sampling. <br /> The samples were collected, preserved and transported under chain of custody and in accordance <br /> with EPA and DHS protocol. The samples were analyzed by Applied Analytical Laboratories <br /> (DHS cert. #1211) for TPHD and BTEX utilizing EPA methods 3510/8015 and 8020, <br /> respectively. Table 2 summarizes analytical results. Attachment 1 contains laboratory data <br /> sheets, chain-of-custody documentation, and well purge logs. <br /> The water samples collected from wells MWi, MW2, MW3, and MW4 were not found to <br /> contain detectable concentrations of any petroleum hydrocarbon. analytes. Monitoring results <br /> substantiate our recommendation for case closure. <br /> wSrioa3.W? <br /> i <br /> i <br /> 1i <br />