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o Prepared a work plan and acquired the necessary <br /> ipermits. <br /> o Drilled two exploratory soil borings in and around the <br /> former tank cluster and collected soil samples to <br /> investigate the subsurface soil. Installed, developed, <br /> monitored, sampled, and surveyed three ground water <br /> monitoring wells. <br /> o Performed laboratory analysis of soil and ground water <br /> samples. <br /> o Prepared this technical report. <br /> 3 . 0 FIELD ACTIVITIES <br /> Alton Geoscience acquired the appropriate SJCPHD permit on <br /> March 17, 1992 , to install three ground water monitoring wells <br /> and drill two exploratory soil borings. A copy of the permit is <br /> presented in Appendix B. <br /> 3 . 1 Soil Borings <br /> On March 24 through 26 , 1992 , Soil Borings SB-1 and SB--2 and <br /> Monitoring Wells MW-1 through MW-3 were drilled onsite <br /> (Figure 2) . MW-1 through MW-3 were installed as 4-inch-diameter <br /> ground water monitoring wells. Ground water was first <br /> encountered at depths of between 65 and 68 feet below grade (fbg) <br /> in the borings (Figures 3 , 4, and 5) . <br /> Prior to drilling, each boring was hand excavated to <br /> approximately 5 fbg to avoid damage to subsurface structures. <br /> Soil Borings SB-1 and SB-2 were drilled using 6-inch-diameter <br /> hollow-stem augers (HSAs) ; MW-1 through MW-3 were drilled using <br /> 10-inch-diameter HSAs. Soil samples were collected at 5-foot <br /> intervals starting at 5 fbg to the total depth of each boring or <br /> monitoring well, except in MW-1. one sample from the capillary <br /> fringe zone was analyzed from each boring or monitoring well. <br /> Additional samples were analyzed selectively based on the highest <br /> observed combustible gas indicator (CGI) readings or field <br /> observations. Soil Boring MW-1 was sampled using a continuous- <br /> core sampler from 5 fbg to the total depth of the boring to <br /> examine stratigraphy (Figure 4) . Drilling procedures and soil <br /> sampling protocol are presented in Appendix C and boring logs are <br /> presented in Appendix D. <br /> 3 . 2 Ground Water Monitoring Well Construction <br /> The monitoring wells were constructed as outlined below. Well <br /> construction details are included in the boring logs, and general <br /> field procedures are presented in Appendix E. <br /> 2 <br />