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5 SCOPE The scope of this investigation will include coordinating access approval for installation of the wells, installation of.five groundwater monitoring wells and one groundwater extraction well, coordination of soil and groundwater disposal, and a complete horizontal and vertical survey of all existing on-site wells and proposed off-site wells relative to a known local benchmark elevation performed by a registered professional surveyor:. Hydrocarbons have been identified in the groundwater in all of the existing monitoring wells on the site. Table 1 presents pertinent'information on each of the proposed wells/boreholes. Wells ATR-8 through ATR-12 have been proposed in order to more completely define the soil and groundwater contamination before remediation takes place, as required by the County. Boreholes BH-1 and BH-2 have been proposed to identify the soil conditions near the underground storage tanks (USTs). One extraction well will be drilled by 8-inch hollow-stem augers and will be continuously cored from the surface to a depth of 20 feet below the water table or piezometric surface. The borehole will be reamed out to total depth using 12-inch augers and will then be completed as a monitoring well by the method described below. The extraction well will be located near ATR-3 as indicated on Figure 1. Groundwater occurs at approximately 11 feet below the ground surface at this site and the extraction well is expected to be approximately 40 feet deep. The immediate purpose of the groundwater extraction well is to provide a means of conducting an aquifer test to determine aquifer characteristics (relevant to the final groundwater remediation system design). The extraction well will be used in the final remediation system design. The question of the discharge of the treated groundwater from the extraction well has not yet been addressed. A schematic of the extraction well construction is shown on Figure 4. The well screen will be selected based upon a grain size analysis performed by Brown and Caldwell on samples collected from the saturated zone of either TEX-1 or BH-2. The proposed well design is intended to accommodate water-level fluctuations and drawdown during extraction within the slotted interval. The proposed well design may be modified in the field during the drilling operation, depending upon conditions encountered during drilling. In no case will the monitoring well penetrate clay zones greater than 5;feet thick (based on field observations of continuous core), which might allow downward migration of contaminants into lower water-bearing zones. Blank 6-inch-diameter Schedule 40 PVC casing will extend from the top of the perforated section to the ground surface. The perforated section will be 25 feet of perforated 6-inch-diameter Schedule 40 PVC. A 5-foot sump will be attached to the bottom of the screen. A bottom plug will be fitted onto the bottom of this sump. The annular space surrounding the well screen and casing will be packed with a filter pack 'I designed to be compatible with the natural formation. The filter will be placed from the bottom of the sump to approximately 2 feet above the top of the screen. The well will then be bailed