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kTj KLEINFELDER ' A-3.4 Equipment Decontami nation To reduce the potential for cross-contamination between wells, all developing and sampling equipment is washed in a trisodium phosphate solution and rinsed in distilled water or steam cleaned prior to use in the next monitoring well. A-3.5 Well Surve ' The locations of soil borings and monitoring wells and the elevation of the top of the PVC casings is usually surveyed and tied into permanent markers, if readily available. Survey accuracy is 0.1 foot for the "x" and "y" coordinates and .01 foot for the "z" coordinate. The rdepth to static ground water is measured from a set location at the top of the PVC casing. The depth of water is then subtracted from the elevation of the top of the well casing to provide a ground water elevation for each monitoring well location. A-4.0 COLLECTION HYDROPUNCH II° GROUNDWATER SAMPLES ' One-time groundwater samples are collected using a Hydropunch II°, which is an in situ groundwater sampling device. The borings will be advanced to a depth equivalent to the bottom ' of the capillary fringe. A stainless steel drive tip equipped with a filter is lowered into the borings at the end of a 2.5-inch diameter galvanized steel pipe and pushed using the drill rig approximately 3 to 5 feet into the soil/aquifer formation at the bottom of the boring. A thoroughly decontaminated bailer can then be lowered down the center of the Hydropunch II° casing to obtain a sample of groundwater (which has entered the Hydropunch IIo due to hydrostatic pressure). To reduce the potential of introducing contaminants into the samples, the drive tip, galvanized pipe, and other equipment used for sample collection are steam cleaned and/or washed with trisodium phosphate (TSP) solution and rinsed with distilled water prior to use. The sample tips and filters are not retrievable. New O-rings, tips, and screens are used for each sample. 1 51726/ST05R157/DH:Iv Page A-5 2005,Kleinfelder,Inc. February S,2005