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LT <br /> Wm. J. Hunter & Associates F1„'}; t } 2220 Loma Vista Dr. <br /> Registered Geologists r +'' t c R�5''(}_' Sacramento, CA 95825 <br /> Petroleum &Mineral Appraisers a (916) 972-7941 <br /> UPPM 12: 23 FAX (916) 972-1683 <br /> April 9, 1997 <br /> Joel Weiss, Engineering Geologist <br /> CRWQCB, Central Valley Region <br /> 3443 Routier Road, Suite A <br /> Sacramento, CA 95827-3098 <br /> Ref: FIRST QUARTER 1997 GROUNDWATER MONITORING REPORT FOR <br /> 1145 W. CHARTER WAY, STOCKTON - INDEPENDENT TRUCKING FACILITY <br /> We have enclosed a copy of the field report, water analysis results, a groundwater gradient <br /> map, and maps showing approximate lines of equal concentrations of benzene, toluene, <br /> ethylbenzene, xylene, TPHg, and TEPH (as diesel) for the above property. The field work <br /> was performed on March 21, 1997 by Del-Tech Geotechnical Support Services as <br /> instructed by our office. The work included the seven (7) wells placed on the Independent <br /> Trucking facility by W. Miles, plus the latest well (MW-9,) recently placed on the JM <br /> Equipment site at 1245 W. Charter Way. MW-5, located in the southeast corner of the <br /> property was installed by Nomellini Construction to monitor the groundwater plume <br /> originating on that property. We are measuring and recording depth to water in this well, <br /> but are no longer collecting and analyzing water samples; that is the responsibility of the <br /> owners of the site to the east. <br /> The groundwater gradient map, PLATE I, shows an unusual pattern. There are two low <br /> areas indicated by the results of the 3/21/1997 work. One is around MW-4, and the other <br /> between MW-2 & MW-8. Prior gradients have been in a north/northeast direction. The <br /> reason for this unique pattern is not known, but could be due to variations in lithology as a <br /> result of the 4 foot rise in the water table since November, 1996. The average depth to <br /> water based on all 9 wells was 17.01' bgl; (-10.72' msl datum.,) a rise of 4' since <br /> November.. <br /> PLATES H through V show the approximate limits& concentrations of benzene, toluene, <br /> ethylbenzene & xylene based upon the latest work. Changes in levels since the last <br /> sampling are summarized below. <br /> MW-1 - Levels are essentially unchanged. <br /> MW-2- All compounds continue to be below detection limits. <br /> MW-3 - Levels of all compounds have decreased. <br /> MW4 - Levels have decreased. <br /> MW-5 - This well was not tested; installed by Nomellini Construction. <br /> MW-6- Well not sampled due to inability to locate surface vault in traffic area. <br /> MW-7 - All compounds continue to be below detection limits. <br /> MW-8 - Levels have decreased <br /> MW-9 - Benzene, toluene, &xylene have decreased; ethylbenzene increased slightly. <br /> t <br />