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1 n � ,. All equipment used during this investigation which might have come into contact with affected materials will be thoroughly decontaminated before and after each use . This will be accomplished by washing with Alconox (a laboratory-grade ►. . detergent) and rinsing with deionized or distilled water. The boreholes will be backfilled with grout upon completion of • soil and groundwater sampling activities . Soil and groundwater sampling activities will take approxi ately one to two working days . 4.2 Monitoring Well Drilling of the three monitoring well will be performed using 8- inch diameter hollow-stem augers . Soil samples will be collected near-continuously from the borings for each well for lithologic description. Additionally, soil samples will be collected by driving a California-type split spoon drive sampler ahead of the hollow-stem augers . Soil samples wilL be collected, starting from the existing ground surface, at 2very 5 feet, at any lithologic changes and areas of obvio s contamination down to the water table. The soil samples will also be screened using a PTD. Assuming a depth to groundwater of approximately 14 feet, five soil samples will be collected from each boring for a total boring depth of approximately 25 feet . Assuming a total boring depth of appr ximately 25 feet, the 15 feet of 4-inch--diameter, 0 . 010-inch slotted casing will be located between the approximate depths of approximately 10 and 25 feet. Approximately 15 feet of flush threaded, 4-inch-diameter PVC solid casing will be installed from the top of the slotted casing to existing grade . The actual length and depth of the well screen installed will be adjusted in the field, based upon the depth to groundwater and the types, depths, and thicknesses of the sediments encountered. The drill augers will then be slowly retrieved from the borehole as the well annulus materials (sand, bentonite, and grout) are added. The slotted interval will be sand packed using Lonestar No . 3 sand or equivalent to a minimum of 2 feet above the uppermost slot. An annular seal will be placed from the top of the sand pack to the surface . The sealing material will be placed in one continuous operation until the specified interval is filled. The annular seal will be a neat cement grout composed of one sack of Portland Type I/II Cement (94 lbs . ) to five gallons of clean water. A bentonite "spacer" not exceeding 1 foot in length will be installed between the sand pack and the cement seal . In the event standing water is present (or more than 30 feet needs to be sealed) , the neat cement grout will be placed by means of a tremie pipe lowered to within three feet of the underlying layer of material or bottom 4