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OR I Site Assessment Proposal Frontier Transportation Doc # 101501 r? I October 15, 1997 f:a protective casing will be set over the well top and surrounded by a surface seal of concrete. -1 The riser and screen will be constructed of two-inch inside diameter, schedule 40 polyvinyl LI chloride (PVC) pipe. Slotted PVC will be extended from approximately 5' bg to termination - depth and it contained 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 ) sized to be compatible with the screen slot size. The bentonite and annular seals are necessary to prevent the annulus from serving as a vertical conduit for potential contaminants. Bentonite pellets will be used to seal the critical area directly above the filter pack. The annular seal will be composed of a mixture of bentonite powder, Portland cement and water. : I 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 i with lockable covers for security. 7. 1 ) Soil Sampling Soil samples will be collected at 5 ' vertical intervals in each well. All samples will be collected through the auger using a split-barrel sampling device. An 184nch long section from each five-foot interval of the soil column will be collected for classifying and logging the site sediments and for chemical analysis (if needed) . -,I For collection of samples for analysis, the sampler will be lined with three, 6-inch long, 2- inch diameter brass sampling rings to contain the soil which were immediately sealed with Teflon i tape, capped and packaged using a PID to detect volatile' organic compounds. The rings will be -- examined for physical'evidence of contamination and for soil classification. Only those soil samples which visual and PID inspection had identified evidence of contamination will be analyzed for petroleum aromatic compounds including MTBE (EPA method 8020) and petroleum hydrocarbons as gasoline (EPA method 8015) at a California Jcertified toxics analysis laboratory. -- 7.2) Groundwater Sampling J Groundwater sampling for dissolved petroleum hydrocarbons will be performed in all -.I groundwater monitoring wells. General steps of the groundwater sampling protocol are ' i 5