ARCHIVED REPORTS_MONITORING WELLS INSPECTIONS, REPAIR AND REDEVELOPMENT REPORT

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• II. Site Geology and Hydrogeology Previous subsurface investigations conducted by Dames and Moore indicates that the site is comprised of the following: • The Dames and Moore, December 20, 1991, Baseline Site Investigation report indicates that the surface material has had a mixture of residual coal, petroleum Coke and Copper concentrate at different times. It should, however, be noted that during the months of January and February, 2003, MSC undertook a extensive surface material removal in order to remove all residual surface materials as was requested by the Port of Stockton's Properties Management Department and the Port's environmental consultant, Jones and Stokes. In addition, in the years past, MSC removed the copper concentrate pile from the property. • According to Dames and Moore, December 20, 1991, Baseline Site Investigation (BSI) report, the native subsurface materials are primarily very fine- grained sediments. There are three classes of materials that are located in three different zones based on their grain size. Silty sand, sandy silt, fine-grained silts, and silty clayey sands make up the first layer. These formations appear to exist in the majority of the site's subsurface as was encountered in previously administered borings by Dames and Moore. • Dames and Moore further reported that the foregoing fine-grained materials were dry, primarily light brown to brown in color, and commonly encountered with iron oxide staining, trace percentage of mica, and small diameter angular to subangular gravel. • The second zone is reported by Dames Moore to contain sandy silt/silty sand zone, which is dark gray, medium, soft, moist, medium to high plasticity clay. Previously administered borings by Dames and Moore indicated that the clay layer extends throughout the majority of the site. Furthermore, this clay layer is reported to extend all the way down to the capillary fringe zone at the point where the clay material transition into other underlying materials. • The third zone is a laterally discontinuous sequence of materials that follow the clay zone. None of the monitoring wells (MW-1through 4) installed Dames and Moore extended beyond this zone. This zone is primarily embedded by brown micaceous silty clay and clayey silt. • According to Dames and Moore's BSI, one saturated zone was identified • beneath the site. The saturated zone is composed of varying lithology and appeared to be continuous beneath the site. The static water table was 2