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�r <br /> Wm. J. Hunter & Associates 2220 Loma Vista Dr <br /> Registered Geologists Sacramento, CA 95825 <br /> Petroleum & Mineral Appraisers (916) 972-7941 <br /> FAX (916) 972-1683 <br /> 1 <br /> January 9, 1997 <br /> ' Linda Turkatte, Sr REHS <br /> San Joaquin County PHS <br /> ' Environmental Health Division - ----�— �" <br /> P 0 Box 388 <br /> Stockton, CA 95201-0388 <br /> ' Ref RESULTS OF GROUNDWATER SAMPLING & REQUEST FOR CLOSURE- <br /> MARCI ' S DIESEL SERVICE, 2969 LOOMIS ROAD, STOCKTON <br /> B <br /> On November 27, 1996, Del-Tech Geotechnical Support Services <br /> r determined depth to water, and purged & sampled monitoring well <br /> #1 at the above site . Water levels were also measured in MW-2 & <br /> MW-3 , but per instructions from the EHD, those wells were not <br /> r' sampled The field work was witnessed by a representative of the <br /> San Joaquin EHD A copy of the field log, chain of custody <br /> forms, and laboratory analyses of the water samples taken from <br /> ' MW-1 are included <br /> The direction of groundwater flow is to the southwest as shown on <br /> EXHIBIT A The gradient continues to be very flat, at about <br /> 0006 ' /ft , or 3 3 ' /mile . EXHIBIT B shows the directions of flow <br /> since monitoring began Depth to groundwater during this event <br /> averaged 67 72 ' below grade, the highest level since monitoring <br /> ' began in April, 1992 There have been a total of 28 water level <br /> measurements taken since the start of the project The maximum <br /> 4 variation in elevation was 6 311 This small fluctuation in <br /> water levels, coupled with the highly divergent gradient, <br /> strongly suggests a very limited aquifer of extremely low <br /> transmrssivity <br /> ' TABLE 1 summarizes all of the results of water analyses since <br /> monitoring began The latest sampling revealed that benzene & <br /> Toluene were below detection levels, ethylbenzene measured 0 4 <br /> ' ug/L, and xylene 0 8 ug/L TPH as gasoline had not been analyzed <br /> since May, 1992 , but because of it ' s presence in the soil boring, <br /> 3t had been programmed to be tested during the October, 1996 <br /> ' event However, that test was not performed, but was included <br /> with the latest work It was measured at 222 ug/L, verbal <br /> communication with the laboratory revealed that it had the <br /> characteristics of degraded gasoline . TEPH (EPA 3510/8015M) was <br /> ' below detection limits MTBE was non-detect from the November, <br /> 1996 sampling, and was not analyzed this time <br /> A comparison of laboratory results from the soil boring placed by <br /> Lush GeoSiences with the last two sampling events of MW-1 is <br /> interesting; the two sates are approximately 20 , apart <br /> n <br /> 1 <br />