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In most places the conglomerate is not well cemented or highly fractured, and consists of loose gravels and sands. The gravel includes pebble size rocks (up to 3" long). In the central wells, MW-1, MW-4, MW-6, the bottom of the conglomerate ranges from 45 to 50 feet bgs. Underlying the conglomerate is silty sand to sandy clay strata. The top of the conglomerate is a stratigraphic marker, as it was found in all borings. The dip is more or less toward the north to northeast. This general dip is evident in the outcroppings in the area. On the site there appears to be a cemented ridge between MW-4 and MW-2 with the highest and hardest portion at MW-4f. From there it slopes in all directions, but is strongest to the north towards MW-7. A map of the top of the conglomerate is presented in Figure 4, in earlier reports. The site hydrogeology is tied to the conglomerate and the underlying gravels. The unconsolidated gravels appear to be the main water bearing zone throughout the site. In the area of the northern wells (MW-3, MW-5, and MW-7) the entire strata of the unconsolidated gravels are saturated, and rise above the conglomerate that serve as an aquitard. Thus the aquifer in northern area of the site is under confined conditions. In the southern wells (MW-1, MW-4, MW-6 and MW-8) the water levels are below the conglomerate, and are underwater table (unconfined) conditions. 3.0 SCOPE OF WORK The following subsections of this workplan presents tasks to further assess potential outfall of the groundwater on the south hillside below SWMU 21, which would possible by indicated by TPH in the soil at what would be the seepage face, and the groundwater conditions south of MW-8. 3.1 Safety Plan Preparation and Implementation The Site Specific Health & Safety Plan (HSP) employed will be the same as that used during previous site evaluations with any warranted updates. The equipment used for the sampling and drilling operation will be the same as used previously (with the additional alternative of mud-rotary drilling). Modifications to the plan may be implemented upon the Direction of the Site Safety Officer or Project Manager if there are any changes in the site or work conditions. 3.2 Permitting Prior to the performance of sampling activities that require the installation of borings, CE will secure permits from the San Joaquin County Public Health Service Environmental Health Division. Installation of soil borings and groundwater monitoring wells (MW), if required, will be in accord with applicable local and State of California requirements. 3.3 Soil Sampling CE proposes to collect three (3) soil samples on the downslope of the hillside south of CE Project No.99R-4041 Additional Investigation Work Plan 3