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Wm. J. Hunter & Associates 2220 Loma Vista Dr. <br /> Registered Geologists Sacramento, CA 95825 <br /> Petroleum& Mineral Appraisers r:��.� (916) 972-7941 <br /> _i FAX (916) 972-1683 <br /> October 20, 1994 L1994 <br /> Steven Sasson, REHS <br /> San Joaquin County PHS Er ".rNTALHEALTH <br /> Environmental Health Division !)SERVICES <br /> 445 No. San Joaquin Street <br /> Stockton, CA 95202 <br /> Ref: SeQQn Buartrgrly Groundwater MonijgKin Repo for ,921 J <br /> EX-em-1 Street, 5tjocktop. <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 by Del-Tech Geotechnical Support Services as directed <br /> by our office. <br /> The attached PLATE I shows the direction of the groundwater <br /> gradient indicated by the three (3) measurements taken to date. <br /> The data shows a shift in the hydraulic gradient to a north- <br /> easterly direction based upon the 9/29/1994 measurements. This <br /> is still in close agreement with both the regional gradient and <br /> �. other monitoring well data in the area. <br /> The results of the laboratory anayaes of the three sets of water <br /> samples collected to date 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, although there has <br /> been a steady reduction in concentration since monitoring began. <br /> However, TPH as gasoline has increased from 50 mg/L in June to <br /> 1800 mg/L in September. The reason for that large increase is <br /> not known. <br /> The water table has risen very slightly since the June measure- <br /> ment; from an average of -4. 69' to --4. 63' MSL; (13. 50' to 13.45' <br /> bgl. ) That does not appear to statistically significant. <br /> CONCLUSIONS= <br /> Based upon the limited data collected to date, the following <br /> conclusions 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 /> 2 MW-2, located in a downgradient position, confirms that the <br /> • contamination has moved northeasterly, which is the indicated <br /> direction of groundwater flow- <br /> 1 <br />