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AA <br /> %-- RESNA WATERWORK CORP, <br /> INDUSTRIES <br /> i <br /> January 30, 1991 <br /> Me. Diane Hinson ¢, <br /> San Joaquin County Public Health Services, <br /> Environmental Health Division <br /> P.Oa Box 2009 r;; <br /> Stockton, CA 95201 <br /> Re: 1991 First Quarter Groundwater Monitoring Report;,,,';, y' <br /> Genstar Western Stone site, 8181 E. Eleventh St. , <br /> Tracy, CA ( County site code: 1393 ) <br /> Dear Ms. Hinson: <br /> s! <br /> This letter presents the results of our 1991 first quarter <br /> groundwater monitoring and sampling at the referenced site. <br /> Activities during the quarter included monitoring depth to <br /> groundwater, purging of wells, groundwater sampling, and analysis <br /> _ of samples for total petroleum hydrocarbons as diesel (TPHD) , <br /> rr' benzene, toluene, ethylbenzene, and xylenes (BTEX) . <br /> f <br /> Groundwater monitoring and sampling was conducted on January 14, <br /> 1991. Depth to groundwater was measured in each well and sub- <br /> tracted from wellhead elevation to determine groundwater eleva- <br /> tion (Table 1) . Water levels in Jahuary.,wexe found to be an <br /> average of .34 feet higher than when last measured in October, <br /> 1990. Figure 1 depicts the groundwater gradient on January 14, <br /> 1991. Gradient magnitude was unchanged since October, 1990 at <br /> approximately .004 ft/ft or 21 ft/mile. Groundwater flow direc- <br /> tion was also unchanged and remains northwesterly. <br /> Water samples were collected from each well on January 14, 1991 ' <br /> after purging and stabilization of pH, conductivity, and tempera- <br /> ture. The samples were analyzed by Applied Analytical laborato- <br /> ries (DHS cert. # 1211) for TPHD and BTEX utilizing EPA methods <br /> 8015 and 8020 , respectively. Table 1 summarizes analytical <br /> results. Attachment 1 contains laboratory data sheets, chain of <br /> custody documentation, and well purge logs. <br /> The water sample collected from MW1 was found to contain 0 . 7 <br /> parts per billion (ppb) toluene and 1 . 7 ppb total xylenes . <br /> Benzene, ethylbenzene, and TPHD were not detected in this sample. <br /> No detectable concentrations of any analytes were found in the <br /> remaining samples. <br /> 1710 MAIN STREET s ESCALON,CA 95320 • (209)838-3507 <br /> 2350•A WALSH AVENUE V SANTA CLARA,CA 95051 (408)49&1249 <br /> i <br /> �I <br />