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A-2 i Soil borings will normally be advanced with 8- or 10-inch-diameter, hollow-stem augers. The soil generated from the soil borings will be wrapped in plastic sheeting and stored on site until characterized for disposal_ 2.0 WATER LEVEL AND LIQUID-PHASE HYDROCARBON (LPH) THICKNESS MEASUREMENTS AND GROUND WATER SAMPLING 2.1 Water Level and LPH Thickness Measurements The static water level and LPH thickness in each well will be measured pnor to purging or sampling The depth to water/product will be measured using an electronic interface probe The wire of the interface probe is marked at 0.01 foot intervals. One tone is emitted from the interface probe if LPH is encountered, another tone for water The wire of the interface probe will be lowered slowly until LPH or water is encountered At this point, the mark on the interface wire opposite the permanent reference point on the top of the well casing will be read to the nearest a 01 foot and recorded. If the first encountered substance is LPH, the probe will be lowered until the tone corresponding to water is emitted. This depth will also be recorded. The difference between the two depths corresponds to the LPH thickness The interface probe will be rinsed in a cleaning solution and deionized water between measurements in different wells A permanent reference point will be marked on the well casings The permanent reference point on the well casings will be surveyed to a common reference point All well casing riser elevations will be known to within 0 01 foot Prior to well development, a disposable bailer will be used to collect a sample of LPH, if present in a well, for subjective analysis. The sample will be collected by gently lowering the bailer approximately one-half the bailer length past the air/LPH interface The appearance (color, opacity, "freshness") will be described and noted on field notes r 2.2 Well Evacuation After the static water level in a well is determined and: prior to collection of a ground water sample, stagnant water will be removed from the well casing and the surrounding gravel pack by bailing, pumping, or with a vacuum truck At least three casing volumes of water will be removed from each well from which a sample was collected.. The volume of water in the casing ' will'be determined from the known elevation of the water surface the well bottom elevation (as measured when the well is installed), and the well diameter r � r r If the well is bailedorpumped during purging, samples will be collected and field analyzed for pH, temperature, and specific conductance The well will be considered stabilized when repeated readings of'the following parameters are within the ranges indicated as follows: I I r` I k I r r I I I I I { ) I