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Ms. Margaret Lagorio Page 3 of 8 Knowles Plume is undefined only to the east of existing well MW8. The proposed monitoring wells should fill this data gap. Drilling and well construction will be performed by a C-57 licensed drilling contractor under the supervision of an experienced geologist. The contractor will advance one soil boring using a rig equipped with 12" diameter hollow stem augers to a total depth of approximately 90 feet below ground surface (bgs), and will construct the well with two parallel strings of 2-inch diameter, Schedule 40 PVC casing and 0.020" slotted screen. The screened intervals will be from approximately 35-55 feet and 70-90 feet below grade. Filter pack will consist of No. 3 Monterey sand from the bottom of the well to approximately 2 feet above the top of the deepest screen (68 feet). The annulus from approximately 68 feet to approximately 56 feet will be completed with 2 feet of hydrated bentonite overlain by neat cement grout emplaced with tremie equipment. The annulus from approximately 56 feet to 33 feet will consist of No. 3 Monterey Sand. The remaining annular space will be completed with 2 feet of hydrated bentonite overlain by neat cement grout tremmied to the surface. At the surface the well will be fitted with a locking cap and water tight, traffic rated well box. Soil samples will be collected at 5-foot intervals during drilling 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. Soil samples will be screened for volatile hydrocarbon content with a photo-ionization detector (PID). Selected soil samples will be submitted for laboratory analysis. At a minimum these will include the sample collected from the capillary fringe and the deepest sample collected. Based upon field evidence of contamination including odors, discoloration and PID readings additional samples may be submitted for analysis. Samples selected for analysis will be immediately capped, labeled and placed in an ice chest at a temperature of approximately 4 degrees Centigrade for shipment to the laboratory under chain of custody protocol. The samples will be analyzed by a state-certified laboratory for TPHg using EPA Method 8015, BTEX using EPA method 8020 and for gasoline oxygenate additives, 1,2 dichloroethane (DCA) and ethylenedibromide(EDB)using EPA Method 8260. Well Development, Surveying and Groundwater Sampling The elevations of the casing collars of the new wells will be surveyed to an accuracy of 0.01 feet and tied into the casing elevations of the existing monitoring well network. A minimum of 48 hrs after well completion, an experienced field technician will measure static depth to water and then develop the wells by pumping and surging until turbidity is minimized. A minimum of three casing volumes will be purged from each well. Subsequent to well development, groundwater samples will be collected from the wells after pH, temperature, and electrical conductivity have stabilized and water levels have recharged to at least 80% of the static levels. Water samples will be placed in appropriate containers, labeled and placed in an ice chest at a temperature of 4 degrees Centigrade for shipment to the laboratory under chain of custody protocol. Analysis will consist of TPHg, BTEX, gasoline oxygenate additives, DCA and EDB. roek\closure\workplmV\ po"se.dw