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i . k%§ KLEINFFLDER �a ' - 3 FIELD ACI'IVITIES To assess the potential presence of petroleum hydrocarbons in the ground water beneath i the site, three soil borings were drilled, converted into monitoring wells, and subsequently developed and sampled. The well locations were triangulated around the site based on r ' held conditions, access, and the anticipated ground water flow direction. Meinfelder's field r.y procedures for the assessment are presented in Appendix B. ra 3.1 DRILLING AND SOIL SAMPLING On February 8 and 15, 199i, three soil borings (B-19 through B-12), were drilled in the vicinity of the tank excavation at 1045 West Charter Way in Stockton, California(Plate 3). The borings were advanced using a truck-mounted drill rig equipped with 8-inch holle.4 4.a stern augers to depths ranging from approximately 50 to 53 feet. Kleinfelder's field procedures for drilling and sampling are provided in Appendix B. A copy of the drilling ' pe.mit is provided in Appendix C. Soil samples were collected at 5-foot intervals from the ground surface to the total depth of the borings. During sample collection, an experienced 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). E Descriptions of the soil encountered in each boring and identification of the sampling ;g. intervals are presented in Appendix A (Log of Borings, Plates A-2 through A-4). 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 wa: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 tl', ,,oil and to monitor the constituent concentrzitions 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 photovac photo-ionization detector (PID) was used to F18.9i-62 3 Copyright 1991 Kleinfelder, Inc.