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Ms.Devra Lewis June 7,2001 Page 6 3.3.2 Drilling and Soil Sampling Procedures SECOR proposes to advance soil borings for the purpose of determining subsurface lithology. Soil samples will be collected from the deepest boring at each location. Soil samples will be collected continuously in 5-foot intervals using a wireline continuous coring system(Moss Sampler) inside the lead auger. Soil samples collected from each boring will be periodically monitored by a SECOR geologist for parameters including odor, staining, volatile organic compounds(VOCs)using a photo-ionization detector (PID),color,grain size, and moisture content. Soil samples will be classified in accordance with the Unified Soil Classification System(USCS)as described in the ASTM Stand D 2488-84 "Description and Identification of Soils(Visual-Manual Procedure)"and recorded onto boring logs, which will be included in the final Summary Report. Augers and associated drilling and well construction equipment will be clean with a high pressure hot water washer prior to drilling each boring. 3.3.3 Monitoring Well Construction Procedures After sampling, 2-inch diameter monitoring wells will be constructed in each soil boring. The proposed construction and anticipated screen interval for each of the seven wells is listed below: TOTAL SCREEN LOCATION WELL ID ZONE DEPTH INTERVAL A MW-9 Upper 42 feet 22-42 feet A MW-10 Middle 58 feet 48-58 feet B MW-11 Upper 40 feet 25-40 feet B MW-12 Middle 60 feet 45-60 feet C MW-13 Upper 38 feet 23-38 feet C MW-14 Middle 57 feet 47-57 feet C MW-15 Lower 85 feet 70-85 feet The well depths and screen intervals listed above are approximate. Actual well construction will be based on the actual subsurface stratigraphy encountered at each location. Multiple wells at a single location will be spaced no less than 5 feet from each other. Boreholes for the Upper Zone monitoring wells(MW-9,MW-11, and MW-13)will be advanced approximately 10 to 15 feet below the first encountered groundwater, anticipated to be 20 feet bgs. Monitoring wells will be constructed within the hollow stem of the augers using approximately 10 to 15 feet of two-inch diameter,flush-threaded Schedule 40 PVC, 0.020-inch machine slotted screen extending from the bottom of the borehole and completed with blank casing to ground surface. A graded sand filter pack will be placed in the annular space from the bottom of the borehole to approximately one foot above the top of the well screen. One foot of bentonite pellets will be placed above the filter pack and hydrated. The remainder of the annular space above the bentonite pellet seal will be filled with a cement-bentonite (5%)grout mixture. H:\Pioneer-Tracy\WorkPlan2001\workplan.doc SECOR International Inc.