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Mr. Jeffery Wong Page 2 WORKPLAN To further evaluate the nature and extent of groundwater impact we propose to install three additional groundwater monitoring wells. Drilling, Well Construction and Soil Sampling Subsequent to obtaining encroachment and well installation permits, three additional groundwater monitoring wells will be constructed in the site vicinity. The proposed locations of the wells are intended to provide coverage of the quadrants to the northeast, southeast and southwest of the site. Coverage of the quadrant to the northwest of the site is provided by the wells located on the U- Haul property. One well will be placed approximately 90 feet southeast of the site. One well will be placed approximately 130 feet north of the site, and one well will be placed near the Robindale Avenue/Wilson Way intersection, approximately 130 feet southwest of the site. Proposed well locations are shown on Figure 3. All work will be performed by a C-57 licensed drilling contractor under the supervision of an experienced geologist. The contractor will advance soil borings using a rig equipped with 8" diameter hollow stem augers. The wells will be completed to depths of approximately 75 feet below ground surface (bgs) to accommodate expected drops in water levels. The screened interval will be from approximately 45 feet to 75 feet bgs to accommodate water level fluctuations. At this site, where water levels have historically been as low as 85 feet below grade and contamination has been detected at depth, a 30-foot screen should be acceptable. The wells will be constructed of 2-inch diameter, Schedule 40 PVC casing and 0.020" slotted screen. Filter pack will consist of No. 3 Monterey sand from the bottom of the wells to approximately 2 feet above the top of the screens. The remaining annulus will be completed with 2 feet of hydrated bentonite overlain by neat cement grout tremied to the surface. At the surface each well will be fitted with a locking cap and water tight, traffic rated well box. Well construction details are presented on Figure 4. During drilling soil samples will be collected at 5-foot intervals for stratigraphic and field screening concerns. All soil samples will be classified in accordance with ASTM Designation D2488-90, which is equivalent to the Unified Soil Classification System. Selected soil samples will be submitted for laboratory analysis. At minimum, these will include samples collected from the capillary fringe. Samples selected for analysis will be immediately capped, labeled and placed in an ice chest at a temperature of 4°C for shipment to a State-certified laboratory under chain of custody protocol. The samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg)using EPA Method 8015, and BTEX using EPA method 8020. Gasoline oxygenate additives, 1,2 dichloroethane (DCA) and ethylene dibromide (EDB) will be analyzed using EPA Method 8260. Well Development, Surveying and Groundwater Sampling The elevations of the casing collars of the wells will be surveyed to an accuracy of 0.01 feet and their latitude and longitude will be surveyed to an accuracy of one meter. After a minimum of 48 hours from completion, an experienced field technician will measure static depth to water and then develop the wells by pumping and surging until turbidity is minimized. \\GZA FS\SYSO1\Data\GROUNDZE\HARRYS\Reports\Workplans\WKPLAN_3MWS RFS.doc