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Wm. J. Hunter & Associates 2218 Loma Vista Drive Registered Geologists Sacramento, CA 95825-0363 Petroleum & Mineral Appraisers (916) 972-7941 FAX (916) 972-1683 U August 8, 2001 Jeffrey Wong, REHS San Joaqluin County Public Health Service Environmental Health Division Site Mitigation Unit 304 E. Weber St, 3rd. Floor Stockton, CA 95202 Re: Second Quarter 2001 Monitoring Report for Valley Wholesale Drug Co., 1401 W. Fremont St., Stockton, Site Code 1782 We are enclosing a report covering the results of the fifteenth sampling event at the above site. It includes the field logs, laboratory results, and maps showing the hydraulic gradient & lines of equal concentration of benzene, ethylbenzene, toluene, xylene, TPHg, & MTBE based on the latest data. The field work was performed on June 26, 2001 by Del-Tech GeoTechnical as directed by our office. PLATE I shows the hydraulic gradient based on the latest work. It has shifted slightly from northwest to almost due north. The hydraulic gradient is about .004'/ft. near the i southeast corner of the building, flattening slightly to .005'/ft. at the north end of the property. This is essentially the same gradient measured in January. The water table was located at an average depth of 7.98' msl datum, a rise of .26' since the January 2001 sampling. The groundwater surface continues to be below the tops of the screens in the 6 monitoring wells - they are at 5' bgl. TABLE A summarizes the measured depths to water since monitoring began. The results of the analyses of water samples from the six monitoring wells since start of the project are summarized on TABLES I, II, III & IV. Levels of benzene in MW-1 (TABLE I) decreased from 34 ug/L in January to 11 ug/L in July. Ethylbenzene decreased from 76 ug/L to 47 ug/L; toluene decreased from 3 ug/L to 1 ug/L, and xylene decreased from 24 ug/L to 15 ug/L. TPH as gasoline decreased from 575 ug/L to 442 ug/L. MTBE was below detection levels in both January & June samplings. MW-2 (TABLE II) has not measured any analytes since December, 1995. All tested substances were below detection levels in MW-3 (TABLE III) in January and June, 2001. TABLE IV lists the three new wells placed in August, 2000 - MW-4, MW-5, & MW-6. BTEX &TPHg were below detection levels in all three in June. MTBE in MW-4 increased from 27 ug/L in January to 66 ug/L in June . MTBE in MW-5 decreased from 74 ug/L in January to 32 ug/L in June. MBTE in MW-6 decreased slightly from 270 to 240 ug/L. between January and June, 2001. • 1 - i