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I Work Plan Frontier Transportation 1099-166 October 27, 1999 dissolved petroleum hydrocarbons (See Figure 7 for Proposed Well Locations). 6. 1) Soil Vapor Survey Soil vapor probes will be advanced to 3 ' bg with a direct push hydraulic rig. An air pump will be used to withdraw the soil vapors. Vapor samples will be collected in labeled Tedlar bags and packaged on ice for transport to a California certified toxics analysis laboratory where they will be analyzed for TPH-g BTEX; and MTBE using EPA methods 8015 modified, 8020, and 8260. 6.2) Groundwater Well Installation A direct push hydraulic drill rig will be used to provide the soil borings for well installation. Drillers will hold a California State C-57 contractor's license. Each well will basically consist of a central section composed of riser and screen. The annular space around the screen will be filled with sand from 5 ' bg to 20' bg. This will be overlain with a 3 ' seal of bentonite pellets, then grouted to near ground surface with a 5% bentonite mixture with cement and water. The bentonite and annular seals are necessary to prevent the annulus from serving as a vertical conduit for potential contaminants. A lockable flush-mount protective casing will be set over the well top and surrounded by a surface seal of concrete. The riser and screen will be constructed of two-inch inside diameter, schedule 40 polyvinyl chloride (PVC) pipe. Slotted PVC will extend from approximately 5 ' bg to 20 ' bg and it will contain three rows of 0. 020-inch slots. Ends of the screen and riser sections will be constructed with flush joining threaded fittings to ensure leak-proof unions. 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 quartz sand (Monterey #3). Following placement of the annular seal, a large-diameter flush-mount protective casing will be installed around the well head. The casing will be firmly seated in concrete and supplied with lockable covers for security (See Figure 6, Well Completion Diagram). 6.3) Soil Sampling Soil samples will be collected at least at 5 ' intervals in each boring and at depths where visual or photoionization (PID) inspection indicates contamination. All samples will be collected in 4-foot clear acetate liners, which are hydraulically pushed into the soil. The sampler will be immediately sealed with Teflon tape, capped, and packaged using a PID to detect volatile organic compounds. Only those soil samples which detect petroleum hydrocarbon vapors using a PID or visual inspection will be analyzed for TPH-g, BTEX, and MTBE at a California certified d