ARCHIVED REPORTS_WORK PLAN TO ESTABLISH BACKGROUND SOIL CONCENTRATIONS

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GES= • GENESIS ENGINEERING&REDEVELOPMENT 1.0 INTRODUCTION Genesis Engineering&Redevelopment,Inc. ("GE&R")prepared this Work Plan to Establish Background Soil Concentrations("Work Plan") on behalf of the William DePaoli Family. The DePaoli property ("Site") consists of the southern 3.5 acres of the former Arcady Disposal Facility located near Holt, California. The Site location and layout are shown on Figures 1 and 2. The data obtained from this Work Plan will be used to establish soil cleanup goals for closure of the Site. 2.0 GEOLOGY AND HYDROGEOLOGY The DePaoli Property is located within the delta complex of the San Joaquin River. The Site is situated between the San Joaquin River proper and a distributary named the Middle River. Whiskey Slough, the water body adjacent to the Site, is connected to the river system and exhibits tidal fluctuation. 2.1 Geology The Quaternary sediments at the Site were deposited on flood plains between distributaries. • At times when channels were in close proximity to the Site, sediments consisting of micaceous clays, silts and sands were deposited. The suite of minerals in the sands indicates a Sierra Nevada source load. At other times the Site was remote enough from major channels that soil deposition was minimal and peat bogs flourished. This has resulted in a stratigraphic sequence consisting of clastic sediments interbedded with I-to 3-foot thick horizons of peat. Drill mud cuttings overlay the native soils at the Site. The drill mud can be distinguished from the underlying native sediments by the lighter color, highly plastic and sticky character when wet, and the lack of mica. Often the contact between native soils and drill mud contains a thin layer of decomposing vegetative matter, apparently vegetation that was growing on the original ground surface that was buried by the drill mud disposal. 2.2 Hydrogeology Depth to groundwater in the shallowest water-bearing zone beneath the Site currently ranges from approximately 6.5 to 17.5 feet below ground surface ("bgs"). Groundwater elevations range from approximately sea level to 11 feet below mean sea level. Shallow groundwater beneath the Site appears to be unconfined. • William DePaoli Property 1 of 5 Work Plan to Establish Background Soil Concentrations February 2012