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.9 <br /> G <br /> April 24,2989 <br /> File No. 1705.2 <br /> I.INTRODUCTION AND PURpOSE <br /> This report describes the work conducted in response to the San Joaquin County Health <br /> Departments request for additional evaluations of the e..tent of contamination at the 102 <br /> So. Wilson Way, Stockton, CA site. Based on the "Preliminary Report for Subsurface <br /> ( E.xploration Program - 102 So. Wilson Way, Stockton, CA" prepared by Balbi & Chang <br /> Associates, Inc., dated September 1, 1988, three additional borings and monitoring wells <br /> were instalied at the site. Chemical tests were performed on selected soil samples from <br /> each boring and one water sample from each well. <br /> The purpose of the investigation is to identify the presence and extent, if any, of contam- <br /> ination of the site soils and groundwater by fuel related hydrocarbons. The work was <br /> authorized by Mr. Don Rock. <br /> II. SUMMARY OF FIELD EV"STIGAT'IONS, PROCEDURES AND TECHNIQUES <br /> The three additional borings and wells w <br /> ere drilled on January 23,` were selected based on past site activity n cooperation with he San Joaqu9. Wlin County <br /> Health Dept staff. <br /> Soil samples were collected otz- "rr"'ll 23, 1989 and preserved for transit to th <br /> testing laboratory. Water samples were collected on anua a chemical <br /> preserved and <br /> transported to the laboratory. The driller was Bay Area Exploration8(C 57 #522125). <br /> Field methods and techniques for soil and groundwater sampling are contained in <br /> Appendix A. Boring logs and monitoring well construction details are shown on Plates <br /> B-1 through B-7 which are presented in Appendix B. <br /> III.SLAY OF SOIL AND GROUNDWATER CONDITIONS <br /> Soils encountered in this additional phase of work were found to be very similar to <br /> previous investigations. Primarily silty clay is present in the upper 40 to 45 feet. Some <br /> �- sand mixed with silt and clay begins at about 35 fee <br /> ownward to silty fine- <br /> grained sand to a depth of 61.5 feet, the ma dmumdeptdh pen its aed. A subsurface soil <br /> L profile depicting the apprommate contacts between soil/sediment litholo ' <br /> ed in Plate 3, gtes is present- <br /> - Groundwater was first encountered at a depth of ab - - - - - ------ - �- - <br /> oringnce <br /> the wells were completed and casings installed, water levels twere.tme estsuredson two <br /> .. ' occasions. The water levels measured are shown below: <br /> 1 <br /> BE <br />