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Sk4 KLEINFELDER Task 2—Subsurface Soil and Groundwater Assessment 2.1 PERMITTING AND PRE-FIELD ACTIVITIES The San Joaquin County Public Health Services Department Environmental Health Division (PHS/EHD) requires completion of a well permit and payment of fees prior to advancing soil borings. Kleinfelder will prepare drilling permit applications for submittal to PHS/EHD along with the required fees. The pern-iits must be approved prior to drilling and sampling activities. PHS/EHD usually requires up to approximately two weeks to issue the permits. The drilling subcontractor will contact Underground Service Alert 48 hours prior to conducting fieldwork to notify local utilities of our proposed subsurface work. Kleinfelder will additionally prepare a health and safety plan prior to proceeding with field activities. 2.2 SOIL AND GROUNDWATER SAMPLING Kleinfelder proposes advancing a total of four borings at the subject site, one for the purpose of collecting a grab groundwater sample in the northwest comer of the site and three in the vicinity of a former underground storage tank (UST). A single SimulProbe boring will be advanced in the northwest portion of the subject site to assess purgeable organics, DBCP and petroleum constituents in groundwater from potential offsite sources of concern in that location. This location is selected based upon the proximity of known upgradient contaminants in the general area of the site. The estimated depth to groundwater based on previous reports in the area of the subject is approximately 60 feet below ground surface (bgs). A former farmhouse UST was noted in the approximate location of a former swimming pool. The UST was reportedly removed and the swimming pool built over the excavation. Kleinfelder proposes advancing the single SimulProbe soil boring to a maximum depth of approximately 70 feet bgs and the three borings in the UST area to approximately maximum depths of 20 feet bgs. During the advancement of the shallow borings in the UST area, soil samples will be collected at five-foot intervals for lithologic classification, qualitative field screening with an organic vapor analyzer (OVA) and potential chemical analyses. The OVA measures ionizable compounds in air in parts per million by volume (ppmv). Specific sampling depths will also be selected based PID readings and field observations with the intent of assessing the potential vertical extent of contamination in the UST area. Soil samples will not be collected from the advancement of the SimulProbe Boring. Lithologic classification will be based on the Unified Soil Classification System (USCS). An experienced environmental engineer or geologist will log the soil borings. All equipment used in the drilling and installation procedures will be cleaned and/or decontaminated as described in Appendix B. 02001PROP.ENV/ST03PO65 Page 4 of 10 Copyright 2003,Kleinfelder,Inc. February 20,2003