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estern <br /> ional <br /> EA ENGINEERING, 41 Lafayette C rc eOperations <br /> SCIENCE, ANO Lafayette,California 94549 <br /> TECHNOLOGY, INC. <br /> (415)283-7077 <br /> M E M O R A N D U M P c E v T <br /> R <br /> NOV ? 198 <br /> DATE: 20 November 1987 HEAt�H <br /> VIRpN1'�'ENTAti <br /> TO: San Joaquin Local Health District <br /> FROM: EA Engineering, Science, and Technology, Inc. <br /> SUBJECT: Monitoring Wells at _22-4$' E . Fremont Avenue, Stockton <br /> EA Engineering, Science, and Technology, Inc. (EA) was retained <br /> by Chevron U. S .A. , Inc. to investigate potential soil and/or <br /> ground water contaminatiou erithe former Chevron Service <br /> Station 9-7780 located at� E. Fremont Street, Stockton, <br /> California. To determine the extent and level of potential <br /> ground water and soil contamination, installation of four <br /> monitoring wells is proposed. Proposed well locations are shown <br /> in Figure 1 . In accordance with San Joaquin County and <br /> California Water Quality Control Board guidelines for monitoring <br /> underground storage tanks for hazardous substances, the holes <br /> i will be drilled to a depth of approximately 60 feet, i .e . , 20 <br /> feet below the estimated static water level . However, if below <br /> the water table at least 5 feet of competent clay layers occur, <br /> the wells shall be terminated 1--2 feet into this clay. The bore <br /> holes will be drilled with a hollow-stem auger. During drilling, <br /> soil samples will be collected using a split spoon sampler with <br /> brass lining, every 5 feet starting at 5 feet below the surface <br /> to the total depth of the bore hole. <br /> The soil samples collected from just above the water table and <br /> samples with detectable fuel contamination will be analyzed for <br /> total petroleum hydrocarbons (TPH) and selected volatile gasoline <br /> constituents (VOA) , using modified EPA 8020, 602, and GC-FID <br /> methods as appropriate . <br /> The bore holes will be completed as monitoring wells with PVC <br /> screen (2-inch diameter, 0 . 020-inch slot, Schedule 40) from 10 <br /> feet above to 20 feet below of static water level or to the <br /> competent clay layer. Above the screen to the surface, Schedule <br /> 40 blank PVC casing will be installed. Each well will be <br /> equipped with a bottom threaded plug and well caps . The annular <br /> space from the bottom to approximately 2 feet above the screen <br /> will be filled with Number 3 Monterey clean sand. The sand pack <br /> will be sealed with 1 foot of Bentonite and a neat cement grout <br /> to the surface . The well will be secured with a water-tight <br /> Py <br /> -C CHV7 . 72P 10 <br /> BALTIMORE 0 CHICAGO 0 CINCINNATI ❑ LINCOLN ❑ NEW YORK 0 SAN FRANCISCO <br />