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31 July 2000 <br /> AGE-NC Project No' ..98-0468 <br /> Page 4 of 11 <br /> monitoring wells (MW-4 and MW-5)were installed in soil borings B-4 and B-5 (Figure 2). MTBE <br /> was detected in two of the eleven soil samples collected at concentrations of 65 µg/kg and 110 j"Ig/kg <br /> (B-4). <br /> TPH-d was detected in the grab ground water samples collected from B'2, B-3, and B-4 (MW-4) at <br /> concentrations of 570 µg/l, 130µg/l, and 660µ;ll, respectively. <br /> 2.3. SITE HYDROGEOLOGIC CONDITIONS <br /> Based on the most recent monitoring event in July 2000 the depth'to ground water underlying the <br /> site is approximately 10.00 feet bsg. Ground water flow direction was calculated to be toward the <br /> north. <br /> 2.4. SITE GEOLOGIC.CONDITIONS <br /> • Infonnation regarding site geologic conditions was obtained from borings and excavations conducted <br /> at the site. Boring logs for the monitoring well'borings describe subsurface soil as primarily <br /> consisting of interbedded sand and clay deposits. Lithology for boring MW-1 was described as <br /> consisting of sand from ground surface to approximately 16 feet bsg and clay from 16 to 30 feet bsg. <br /> Subsurface soil encountered in boring MW-2 was described-as consisting of sand from ground suface <br /> to 8 feet bsg, underlain by clay from 8 to 13 feet bsg, and sand deposits from 13 to 30 feet bsg. In <br /> boring MW-3 fill material was described from ground surface to 12 feet bsg and sand deposits from . <br /> 12 to 30 feet bsg. However, during site characterization activities, shallow subsurface soil at the site <br /> was reported to consists_ primarily of clay from ground surface to a depth of 16 feet'bsg (Twining, <br /> 1997). . <br /> 2.5. -RECEPTOR WELL SURVEY <br /> A survey was performed to identify potential receptor wells near the subject property. The City of <br /> Stockton and California Water Service was contacted for the location and construction specifications <br /> for municipal wells near the site. A database from the California Department of Water Resources <br /> (DWR), driller's well log files and.a well location map prepared by the San Joaquin County-Flood <br /> Control and Water Conservation District (SJCFC&WCD) were examined to locate wells near the <br /> site. A 2,000 foot search radius from the site was used. Owners/residents of nearby properties of the <br /> site were contacted regarding wells near the site. <br /> Admiced GeoEnvironmental,Inc. <br />