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+ Ream the hole with 10-inch diameter bit to a depth of 2 feet below the top of the confining layer. • Install an 8 3/-inch diameter steel conductor casing within the boring and grout up to surface with cement-bentonite grout containing approximately 2 percent non-beneficiated bentonite.Grout mixture will not exceed 7-1/2 gallons of water for each 94-pound bag of cement. The grout will be pumped through a tremie pipe from the bottom of the borehole to the surface. The grout will be allowed to set for 24 hours before continuing well installation. • All water will be removed from the conductor casing and checked for leakage prior to continuing drilling. • Drill through bottom of conductor casing with 6-inch diameter bit using mud-rotary. • Soil samples for lithologic description shall be taken continuously from the bottom of the conductor casing using a 94 mm core system until the next water-bearing zone is encountered and defined. • Install a 2-inch diameter Schedule 40 PVC casing and 10 feet of 0.020-inch slot well screen following the methods described above. 3.2.2 Extraction Well Installation One extraction well will be installed to a depth of approximately 120 ft bgs at the location shown in Figure 2. The exact depth of the screen interval will be determined in the field.Installation procedures are as discussed in Section 3.2.1,with the following exceptions outlined below. • Drill a 6-inch diameter pilot boring to approximately 120 feet bgs using mud-rotary drilling methods. • Soil samples for lithologic description shall be taken continuously from 50 feet to approximately 120 feet bgs using a 94 mm core system.Additionally,up to two soil samples will be collected at depths to be determined in the field.The samples will be labeled,placed in ziplock bags,and placed in an ice- filled cooler. Soil samples will be analyzed for TPH-gas,benzene,toluene,ethylbenzene,xylenes (BTEX),CAM 17 metals,bulk density,specific gravity,total organic carbon (TOC),and oxygenates, including 1,2-Dichloroethane(1,2-DCA), 1,2-Dibromoethane(EDB),and tert Butanol(TBA),by EPA Method 8260, in a state-certified laboratory. • Ream hole with 10-inch diameter bit. 0 The extraction well will have a sediment trap with 2 feet of blank stainless steel casing,approximately ! 20 feet of stainless steel flush threaded 0.040 slot screen,and 6-inch OD Schedule 80 PVC casing to the ground surface.#8/16 Monterey sand shall be used as the filter pack. The well shall be completed with well monument with a minimum diameter of 36 inches. The exact screen interval will be determined in the field. Potential groundwater and soil sample analyses associated with the CPT Investigation and well installation are summarized in Table 1. Table 2 summarizes the required sample containers,preservations, and holding times. 3.2.3 Aquifer Testing ? An aquifer pumping test will be performed on the newly installed extraction well to assess the hydraulic properties and maximum pumping rate of the impacted zone. CATEMP\WaRKPuw_DCA 1.Doc 7