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y'�� - _"" v.G..�. -...� �. _ ..l ��, q 3viii.-1.'-a. �' •. d. WN;M ,4+ t%,j XL'vFELDER w 3 FIELD,ACTIVITIES io assess the potential presence of petroleum hydrocarbons in the ground water beneath the site, three soil borings were drilled, converted into monitoring wells, and subsequently it developed and sampled. The well locations were triangulated around the site based on field conditions,access,and the anticipated ground water flow direction. Kleinfelde:s field procedures for the assessment are presented in Appendix B. rpt 3.1 DRILLING AND SOIL SAMPLING eu On February 8 and 15, 1991, three soil borings (B-10 through B-12), were drilled in the vicinity of the tank excavation at 1045 Vilest Charter Way in Stockton, California (Plate 3). The borings were advanced using a truck-mounted drill rig equipped with 8-inch hollow i•, stern augers to depths ranging from approximately 50 to 53 feet. Kleinfelder's field rA procedures for drilling and sampling are provided in Appendix: B. A copy of the drilling ' permit is provided in Appendix C. 4.a" Soil samples were collected at 5-foot intervals from the ground surface to the total depth of the borings. During sample collection, an expe,:erced environmental geologist classified the subsurface soil and logged the boreholes. A copy of the Unified Soil Classification System used to classify the soil and a log key are provided in Appendix A (Plate A-1). f Descriptions of the soil encountered in each boring and identification of the sampling 't of Borings, Plates A-2 through A-4). Intervals a�e presented in Appendix A (Lag s g 1; Generally, the soils encountered beneath the site were silty sand from ground surface to approximately 35 feet, and fine to medium grained sand with some silt or clay from approximately 35 feet to the total depth of each boring. The soil was generally moist. Ground water was encountered in the borings at approximately 35 to 38 feet. 3.2 QUALITATIVE FIELD SCREENING To provide a qualitative indication of the presence of volatile organic constituents in the soil and to monitor the constituent concentrations in the breathing zone,a portable organic vapor analyzer (OVA) was used to screen the samples in the field. A Foxboro flame ionization;detector (FID) and a ph otovac photo-ionization detector (PID) was used to 4 F18-91-62 Copyright 1.991 K3einfeider, Inc.