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J Hunter & Associates ' _ � <br /> Wm. 2220 Loma Vista Dr. <br /> Registered Geologists Sacramento, CA 95825 <br /> Petroleum& Mineral Appraisers (916) 972-7941 <br /> FAX (916) 972-1683 <br /> September 21, 1994 <br /> - Linda Turkatte, RENS <br /> San Joaquin Co. PHS <br /> Environmental Health Division <br /> 445 No. San Joaquin Street <br /> Stockton, CA 95202 <br /> Ref: QUARTERLY GROUNDWATER MONITORING REPORT and REQUEST FOR SITE <br /> CLOSURE: 2969 Loomis Road (Site Code 2015) <br /> Dear Ms. Turkatte; <br /> We have enclosed a copy of the field log, chain of custody form, <br /> and laboratory analyzes of water samples taken from all three <br /> monitoring wells on August 31, 1994. From September 15, 1992 <br /> until May, 1994, only MW-1 had been sampled. However, water <br /> level measurements have been taken monthly since May, 1993. <br /> Because there has been a constant decrease in the levels of con- <br /> taminants detected in MW #1, it was decided to test all three <br /> sells in May, 1994; the results showed that all wells were below <br /> detection limits for BTEX & TPH-D. On August 31, 1994, all three <br /> wells were again sampled using rigorous field protocol, (details <br /> attached, ) to confirm the prior laboratory readings. As listed <br /> on TABLE I, the results were again below detection limits for <br /> BTEX & TPH-D. Copies of the laboratory sheets are included in <br /> this report. <br /> A review of water level measurements since the last sampling in <br /> May, 1994, shows a gradual lowering of the water table of about <br /> 2. 5 feet to an average depth of 71. 85' bgl_ The highest level <br /> recorded since monitoring began was 69. 41' bgl, (average) in May, <br /> 1994; the lowest was in September, 1992 - '14. 03' bgl, (average. ) <br /> The attached EXHIBIT A shows the pieziometric surface as of <br /> 8/31/94; the indicated gradient is to the southeast. The direct- <br /> ions of all groundwater gradients measured since monitoring began <br /> are labeled on the attached EXHIBIT B. The data continues to show <br /> a variable gradient, although the last 5 have been in a south- <br /> easterly direction. <br /> CONCLUSIONS: <br /> f' Based upon the results of the data obtained to date, the following <br /> conclusions appear to be warranted: <br /> 1. The 22 water table measurements taken over a period of 2+ <br /> years shows that the hydraulic gradient has been widely variable, <br />--tib <br /> 1 <br />