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I <br /> Wrn. J. Hunter & Associates -± -� 2220 Loma Vista Dr. <br /> Registered GeologistsSacramento, CA 95825 <br /> Petroleum& Mineral Appraisers L� E 9� SQ (916) 972-7941 <br /> t FAX (916) 972-1683 <br /> November 18, 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 : Ninth 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 November 5, 1996 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 nine (9) measurements taken to date . <br /> The gradient continues in a northerly direction at about <br /> . 057 ' /ft . <br /> The water table was measured at an average depth of 10 .44 ' bgs, a <br /> drop of slightly over one foot since the June sampling event . <br /> The results of the laboratory anayzes of water samples collected <br /> since monitoring began are shown on TABLE I . Monitoring wells #1 <br /> & #4 are below detection levels for BTEX & TPHg. MW-3 was ND for <br /> benzene, toluene, ethylbenzene & TPHg, but xylene was detected at <br /> 0 . 4 ug/L. This is the first time this well has recorded any <br /> contamination, and the source is not known. Del-Techs ' field <br /> protocol is very strict, and all equipment is thoroughly decon- <br /> taminated both before and after use . Based on prior data, it is <br /> likely that the minor amount of xylene was introduced during <br /> sampling, handling or laboratory procedures, and is not represen- <br /> tative of the groundwater at this location. <br /> MW-2 was not sampled during this event per SJCoEHD approval . <br /> However, in order to determine current levels of contamination, <br /> all four wells will be sampled and analyzed during the next <br /> event . This data will assist in evaluating evidence for natural <br /> atten tion and proposing additional work, if necessary. <br /> Wm. J unter & Associates <br /> c eth Thayer, CVRWQCB ,. <br /> ;. G. Le ch i c h Nf`LL11 J.HUs iER <br /> M. Griffin <br /> N0.660 , <br /> 1 r9�of <br />