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Wm. J. Hunter & Associates 2220 Loma vista or. i <br /> _ <br /> Registered Geologists Sacramento, CA 95825 <br /> Petroleum.& Mineral Appraisers (916) 972-7941 <br /> FAX-(916) 972-1683" <br /> January 9, 1997 <br /> Linda Turkatte, Sr. RENS; <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 /> On November 27, 1996, Del-Tech Geotechnical .-Support Services <br /> 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 ERD, those wells were not <br /> sampled,* <br /> The field work' was witnessed by ,a representative of the <br /> San Joaquin EHD. A copy;; of the field log., chain of custody. - J <br /> forms, and laboratory analysers 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 /> ..00061 [ft or 3 . 3 ' /mile: EXHIBIT B shows the directions of flow <br /> since monitoring .began. ' Depth to groundwater during this event <br /> t1 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 /> variation in elevation was 6 :`31 ' . This' small fluctuation in <br /> water levels, coupled with the highly divergent gradient, , <br /> strongly suggests a very limited aquifer of extremely low j <br /> transmissivity. <br /> + TABLE l , 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 i <br /> ug/L, and xylene 0 . 8 ug/L.. TPH as gasoline had not been analyzed f <br /> since May, , 1992, but because of it ' s presence in the soil boring, !� <br /> it 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/t; verbal <br /> communication with the laboratory revealed that it had the <br /> characteristics -of degraded gasoline. TEPH (EPA 3510/8015M) was <br /> I 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 sites are approximately 20 ' apart : <br /> �-.� 1 <br />