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DRAFT <br /> The well will be installed using hollow-stem auger drilling equipment using the dual auger techniques <br /> outlined in the Phase IV Hydrogeologic Investigation(CH2M HILL, 1996). The upper Zone A will be drilled <br /> and sampled with 6 1/4-inch inside diameter augers. At the first occurrence of groundwater a Hydropunchlm <br /> grab groundwater sample will be collected. Following the collection of the groundwater samples, small <br /> diameter augers will be used to drill down to Zone B. Soil samples will be collected and logged every 5 feet. At <br /> the top of Zone B another HydropunchTm sample will be collected. If the HydropunchTM sample from Zone B <br /> contains PNAs,the alternative well location will be used for the new Zone B well. In addition the <br /> Hydropunchrm samples will be compared to other HydropunchTm samples that have been collected in the area <br /> during previous investigations. <br /> Once the Hydropunchm sample is collected the small augers will be removed. The borehole will be reamed to <br /> 10-inch diameter down to 115 feet bgs and a 4-inch diameter monitoring well will be constructed. The boring <br /> will be completed as a monitoring well with 4-inch-diameter, flush-threaded, Schedule 40 PVC casing and <br /> 0.010-inch factory slotted, 2-inch-diameter,flush-threaded PVC screen. The annular space around the slotted <br /> screens will be filled with clean graded sand(Lonestar#2/12)to approximately 2 feet above the top of the <br /> screened interval. After the filter pack is in place,the driller will bail 3 to 4 casing volumes of groundwater <br /> from the inside of the casing to predevelop the well and ensure a quality filter pack around the screened <br /> interval. A bentonite seal at least 2 feet thick will be placed above the filter pack, and the remaining annular <br /> space will be filled with a cement-bentonite slurry using the tremie method. The surface completion will <br /> consist of a flush-mounted traffic-proof vault box with a locking water tight cap on the well head. Figure 4 <br /> shows the typical monitoring well construction details. <br /> The monitoring well will be developed no sooner than 24 hours after installation. The development will be <br /> performed with a combination of bailing,surging,and pumping until the water is clear and the pH, <br /> conductivity,and temperature stabilize. Conductivity will be considered stabilized when three consecutive <br /> readings are within 10 percent agreement and pH is within 0.5 units. A minimum of 10 casing volumes will be <br /> removed. Accumulated fine-sized materials will be removed from the well. Water level and flow rate <br /> measurements will be recorded while purging the well to provide data to estimate the aquifer's transmissivity. <br /> Groundwater will be contained temporarily until it can be disposed of on-site through the sanitary sewer. <br /> Analytical Procedures <br /> Listed below are the analytical parameters and the purpose for the sample analysis during this investigation: <br /> Area I-Confirm/Modify Dimensions of Source Areas 1 and 4 <br /> Source Areas 1 and 4 <br /> Four borings, approximately 7 soil samples per boring will be analyzed for: <br /> Parameter groups: PNAs,TPH-diesel,TPH-gasolirie,and BTEX <br /> Purpose: To determine the edge of the COC-affected soil adjacent to the <br /> source areas. To determine the vertical profile of COC <br /> concentrations outside the source area. <br /> Area I-Determine Leachability of COCs using DI WET <br /> Source Area 2 <br /> One boring, two soil samples Source Area 2 <br /> Parameter groups: PNAs,TPH-gasoline,TPH-diesel,and BTEX <br /> Purpose: To establish concentrations of COCs in samples used for DI WET. <br /> Source Areas 1,2, and 4 <br /> SFO/G:A:IOl 1.DOC 4 <br />