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Wm. J. Hunter & Associates _ 1-711 2220 Loma Vista Dr. <br /> Registered Geologists _ Sacramento, CA 95825 <br /> etroleium& Mineral Appraisers - (916) 972-7941 <br /> �2'' 7 FAX (916) 972-1683 <br /> ,r October 5, 1995 <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 : Fifth 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 July 18, 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 six (6) 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 an average <br /> of 1' -1001 , or approximately 53 ' /mile. <br /> The results of the laboratory anayzes of water samples collected <br /> since monitoring began are shown on TABLE I . To date, neither <br /> BTEX or TPH-G have been detected in water samples from MW-1 or <br /> MW-3 . MW-2, directly downgradient from the site of the removed <br /> UST, still shows significant levels of BTEX & TPH-G. However, <br /> the amounts of those components have decreased since the March, <br /> 1995 sampling event . This change could be caused by the slight <br /> drop in the groundwater surface since July, ( .58 feet, ) natural <br /> bioremediation, or other factors . <br /> An analysis of data to date shows that the water table is begin- <br /> ning to drop after reaching a high in March, 1995 . This is to be <br /> expected since there has been no rainfall since last spring, and <br /> withdrawals from deeper aquifers are causing a lowering of water <br /> levels . <br /> CONCLUSIONS : <br /> Based upon the data collected to date, the following conclusions <br /> appear valid: <br /> 1 . MW-1 & MW-3 indicate that the limits of the plume have been <br /> defined to the east, south, & west of the UST site. <br /> 1 <br />