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Wm. I Hunter & ASSOC1ateS E_t <br /> , F � r'�' � ,� ; 2220 Loma Vista Dr. <br /> Registered Geologists Sacramento, CA 95625 <br /> �etroleum& Mineral Appraisers e.i k r (916) 972-7941 <br /> ` FAX (916) 972-1683 <br /> March 14 , 1994 <br /> Michael Collins, RENS <br /> San Joaquin County PHS <br /> Environmental Health Division <br /> 445 No. San Joaquin Street <br /> Stockton, CA 95202 <br /> Ref : SECOND QUARTERLY GROUNDWATER MONITORING REPORT-- <br /> 1500 Shaw Road, Stockton, CA, (Site Code 1727) <br /> Dear Michael; <br /> We are enclosing the results of the second quarterly report <br /> covering groundwater monitoring activities at the above site, <br /> which Were performed on January 27, 1994 . <br /> The first groundwater measurements were taken on June 3, 1993, <br /> shortly after installing the four wells The details of that <br /> work was discussed in detail in the PAR & Groundwater Investiga- <br /> tion Report prepared by this office, and submitted to the EHD in <br /> August, 1993 Measureable levels of BTEX & TPH-G were observed <br /> in all four wells ; the highest readings were noted in MW-1 , which <br /> was in an upgradient position from the site of the removed UST' s . <br /> The gradient as measured in June was essentially due south, <br /> towards MW-3 Based on County flood control district maps , the <br /> regional gradient is in a westerly direction in this area <br /> The water measurement & sampling performed in September revealed <br /> these significant facts <br /> 1 The water table had dropped approximately 4 feet in the 3 1/2 <br /> months between measurements. <br /> 2 . The groundwater gradient had not changed significantly in <br /> that time; still almost due south. <br /> 3 . Levels of Benzene & TPHG had dropped considerably in the <br /> second set of readings in MW-1 & MW-2, but increased in MW-3 & <br /> MW-4 . <br /> 4 Levels of Toluene & Xylene decreased in MW-1 between the two <br /> measurements, but increased in the other three wells <br /> 5. Changes in the amounts of Ethylbenzene were not statistically <br /> meaningful <br /> Analysis of the data from the January, 1994 field work is <br /> summarized below. <br /> 1 . The water table has dropped an average of slightly over 2 . 25' <br /> . since the measurements taken in Sept 1993, and over 6' since <br /> 1 <br />