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Bank of Stockton Cutter Lumber Site Page 9 Groundwater Monitoring Well Construction ' Project No 102 2 April 24, 1998 ' 3.0 FIELD & ANALYTIC DATA ' 3.1 Site Geology & Hydrology ' Site Geology Observed The geology observed during the completion of the borings in the area can generally be characterized as medium to dark brownish gray clays and silts (see ' cross-section, Figure 8) at depths above 60 feet There are also thin, semi- continuous beds of sand and silty sand In general, the soils are very fine and have a slightly plastic to moderately plastic deformation character It is ' apparent that the material generally has low permeability These soil characteristics are suggestive of deposition in a low energy, fluvial, over-bank environment Soil from about 65 feet to the deepest depth observed (90 feet) ' appear to be composed almost entirely of very fine to medium grained sand Specifics on individual borings and sampling intervals are described below Boring logs are attached in Appendix B I MW-6 This boring was completed about 30 feet south of the tank pit The shallowest significant petroleum odors and staining were encountered at about 40 feet, and persisted to the bottom of the boring at 45 feet The highest levels of gasoline in ' the soil occurred at about 10 to 15 feet below the groundwater surface Free water was encountered in this (and the other borings) at a depth of about 25 feet The soils consisted of silt and clay except for relatively minor sand layers Iat about 20 feet and 40 feet MW-7 This boring was completed to a depth of 45 feet through pit of the former 1,000 gallon gasoline UST identified in the previously cited reports The tank pit is about 7 feet deep and below the level of the fill material, the soil exhibits petroleum staining and odor down to the groundwater Soil samples consisted of clay and silt except for a sandy layer at about 40 feet MW-8A This boring was completed about 30 feet northeast of the release site near the I southwest corner of a steel frame building Gasoline impacted soil was encountered at a depth of about 30 feet, and persisted to the bottom of the initial boring at 50 feet At that point, 49 feet of conductor casing was set and cemented as described above When drilling resumed, gasoline impacted soil was again encountered to a depth of about 55 to 60 feet where field techniques no longer suggested the presence of gasoline The soil in this boring was mostly 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 Modesto,CA 95356 Fax (209) 569-0293