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7,n CDM Camp Dresser&McKee Inc. Mr. Amin Kazimi March 30, 2001 Page 2 - boring B2 to a depth of 50 feet bgs. The initial five feet of each boring will be hand augered. Representative soil samples will be obtained from the borings at encountered stratigraphic changes. A California Split Spoon Sampler will be used to extract the soil samples. Soils will be classified in accordance with the United Soil Classification System. Upon completion,boring B1 will be backfilled with a mixture of 95%Portland neat cement and 5%bentonite. A piezometer will be installed in boring B2. Piezometer construction details are shown in Figure 3. The piezometer will be completed to an approximate depth of 45 feet (bgs) with a screened interval from approximately 25 to 45 feet bgs, depending on the depth of groundwater. The piezometer will be constructed of 2-inch diameter,schedule-40 PVC,with a 20-slot screen, and a stick-up completion. Between 0 and 19 feet bgs, the annulus will be filled with grout (5% bentonite and 95% Portland neat cement). From 19 to 22 feet bgs, the annulus will be filled with 0.25-inch bentonite pellets. Between 22 and 50 feet bgs, the annulus will be filled with#3 Lone Star sand or equivalent. A tremmie pipe will be used to place the filter pack and grout. The filter pack will be stabilized using surge block techniques prior to placement of the bentonite seal. 3.0 Sampling and Analysis Two soil samples will be collected from boring B2 and analyzed for corrosion susceptibility to determine if corrosive chemicals are present in the site soils. One sample will be collected at approximately 2 feet bgs, and one sample will be collected at 27 feet bgs. A grab sample will also be collected from the soil stockpile. The grab sample will be analyzed if corrosive chemicals are detected in the soil samples collected from boring B2. The samples will be tested by an outside laboratory for resistivity,pH, sulfate, and chloride. Two soil samples will be collected analyzed to identify possible soil contamination at the Site. One sample will be obtained at approximately 2 feet bgs from borings B1 and B2. All samples will be retained in 6-inch brass tubes, capped with Teflon tape and plastic caps, properly labeled,placed in plastic ziplock bags, and stored in a cooler with ice. The samples will be analyzed (pH, fecal coliform, and chromium VI) if the grab groundwater sample indicates contaminant detections. Geotechnical laboratory testing will be performed on selected soil samples collected from B1 and B2. The samples will be selected based on the geologic logs of borings B1 and B2. Laboratory testing will include a maximum of 8 density and moisture content tests, 2 grain size distribution analyses to better define the permeability characteristics, and 2 strength tests for design of the temporary excavation support. One grab water sample will be collected from the piezometer. Prior to collection of the groundwater sample, the piezometer will be developed and purged until the temperature, pH, conductivity, dissolved oxygen, and turbidity of the groundwater have NAPrpjMTOCKT0N\6rookside Pumplwprkplan032901.doc