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clean glass container and covered with aluminum foil and covered with a screw lid. A <br /> photoionization detector(PID) is used to analyze the headspace of the samples. The PID will <br /> be calibrated using calibration gas. The results of this screening will be used for selection of <br /> representative samples for laboratory analysis, and as data for determining the boring depth. <br /> • All soil samples will be described in the field. Field observations noting sediment type, <br /> color, grain size, sorting, hardness, texture, clay content, moisture content, visible evidence <br /> of contamination, odor, and any other information important to the investigation. <br /> These soil sampling procedures are designed to: <br /> • ensure that representative soil samples are collected and accurately described in the field. <br /> " • ensure that all boring logs, sample descriptions, and field observations are consistent and <br /> accurate. <br /> • minimize the risk of cross-contamination between samples. <br /> -- 3.3 Well Water Sampling Procedures <br /> Prior to sampling of monitoring or other wells, the water level will be measured and the wells <br /> will be purged of three to five casing volumes or until well is dry. Bailers or submersible pumps <br /> used for purging will be thoroughly cleaned before and between samples, or disposable bailers <br /> may used. The amount of casing volume of water in the well can be calculated with the formula: <br /> r2 X (hl -h2) X 7.48 gallons/ft3 = gallons/casing volume, where: <br /> r= inner radius of casing (ft) <br /> hl = depth of well (ft) from top point measurement (normally from <br /> reference mark in casing) <br /> h2 = depth to water(ft) from to of point of measurement(POM). <br /> American Geological Services, Inc. <br /> 4 <br />