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Wm. J. Hunter & Associates 2220 Loma Vista Dr. <br /> Registered Geologists Sacramento, CA 95825 <br /> Petroleum & Mineral Appraisers <br /> (916) 972-7941 <br /> 56 FAX (916) 972-1683 <br /> January 5, 1996 <br /> Steven Sasson, REHS <br /> San Joaquin County PHS <br /> Environmental Health Division <br /> 445 No. San Joaquin Street <br /> Stockton, CA 95202 <br /> Ref : Sixth Quarterly Groundwater Monitoring Report for 921 W. <br /> Fremont Street, Stockton. <br /> Dear Mr. Sasson; <br /> We have enclosed a copy of the field report , water analysis <br /> results, and a gradient map for the above property. The work was <br /> performed on December 7, 1995 by Del-Tech Geotechnical Support <br /> Services as directed by our office . <br /> The attached PLATE I shows the direction of the groundwater <br /> gradient indicated by the seven (7) measurements taken to date . <br /> The data continues to show the hydraulic gradient is to the <br /> north; only the 9/29/1994 sampling event showed a northeasterly <br /> direction. The gradient continues to be very low at about <br /> . 831 /100 ' , or approximately 44 ' /mile . . <br /> The results of the laboratory anayzes of water samples collected <br /> since monitoring began are shown on TABLE I . Monitoring well #3 <br /> continues to below detection levels for BTEX & TPHg. MW-1 <br /> revealed minor amounts of toluene & xylene during the latest <br /> sampling period. However, the toluene may be a result of con- <br /> tamination measured in the bailer blank - refer to the laboratory <br /> sheets for more information. MW-2 , in a downgradient position <br /> from the removed UST, continues to record significant amounts of <br /> BTEX & TPHg; in fact, the levels have increased since the July <br /> sampling event . <br /> The water table was measured at an average depth of 12 . 31 ' bgs <br /> during the December sampling event . This is a drop in water level <br /> k of 3 ' since July, and 3 . 571 since the March, 1995 sampling. <br /> CONCLUSIONS : <br /> Based upon the data collected to date, including the geoprobe <br /> work done on November 27 & 28, 1995, the followi <br /> appear valid: ng conclusions <br /> I . MW-1 & MW-3, and soil probes A-1, A-2, B-2 indicate that the <br /> limits of the soil & water plume have been fairly well defined to <br /> 1 <br />