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Frontier Transportation, Inc. 425 Larch Road Site Assessment Work Plan May 6, 2005 ' Page 4 for shallow well installation will be advanced to 20 ' bgs. Each well will basically consist of a central section composed of riser and screen. The riser and screen will be constructed of two-inch inside diameter, schedule 40 polyvinyl chloride i (PVC) pipe. The proposed shallow wells will consist of slotted PVC extend from approximately 20 ' bgs to 5 ' bgs and it will contain three rows of 0 .010-inch slots. The annular space around the screen will be filled with an appropriate grain size of sand from 20 ' bgs to 4.5' bgs to form a f filter pack. This will be overlain with a 1 ' seal of bentonite pellets, then grouted to near ground surface with a 5% bentonite mixture with cement and water (See Figure 4). Ends of the screen and riser sections will be constructed with flush joining threaded fittings to ensure leak-proof ( unions. I A filter pack of sand will be placed around the screen to retain the finer grained fractions of formation material and to create a zone of high permeability that allows free entry of water in ` the well. The pack will consist of clean sand (#2/16) . The bentonite and annular seals are ! necessary to prevent the annulus from serving as a vertical conduit for potential contaminants. l Following placement of the annular seal, a large-diameter flush-mount protective casing will be installed around the well heads. The casing will be firmly seated in concrete and supplied with I lockable covers for security. I f " 5. 1) Soil Sampling A total of four soil samples will be collected from each of the three shallow wells. Soil samples will be collected at least at 5 ' intervals from the boring and at depths where visual or PID inspection indicates contamination. All samples will be collected in a split spoon sampler lined with 24nch by 6-inch brass tubes. The bottom brass tube will be immediately sealed with Teflon tape, capped, and packaged in a cooler with ice. The second brass tube will be field screened using a PID to detect volatile organic compounds and used to classify soil sediments. All soil samples that detect petroleum hydrocarbon vapors using a PID or visual inspection will be submitted to a California certified laboratory for analysis. All soil samples submitted to the laboratory will be analyzed for TPH-g, BTEX, and MTBE and oxygenates using EPA methods 8015 modified and 8260. O )L 5.2) Analytical Methods and Quality Assurance A California Department of Health Services certified laboratory would conduct lil