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44 <br /> GR Field Methods and Procedures <br /> Water-Level Measurements <br /> Prior to sampling each well, the static water level is measured using an electric sounder and/or <br /> calibrated portable oil-water interface probe. Both static water-level and separate-phase product <br /> thickness are measured to the nearest ±0.01 foot. The presence of separate-phase product is <br /> confirmed using a clean, acrylic or polyvinylchloride (PVC) bailer, measured to the nearest }0.01 <br /> foot with a decimal scale tape. The monofilament line used to lower the bailer is replaced between <br /> borings with new line to preclude the possibility of cross-contamination. Field observations (e.g. <br /> product color, turbidity, water color, odors, etc.) are noted. Water-levels are measured in wells <br /> with known or suspected lowest dissolved chemical concentrations to the highest dissolved <br /> concentrations. <br /> Sample Collection and Labeling <br /> A temporary PVC screen is installed in the boring to facilitate a grab groundwater sample <br /> collection. Samples of groundwater are collected from the surface of the water in each well or <br /> boring using the Teflon bailer or a pump. The water samples are then gently poured into <br /> laboratory-cleaned containers and sealed with Teflon-lined caps, and inspected for air bubbles to <br /> check for headspace. The samples are then labeled by an adhesive label, noted in permanent ink, <br /> and promptly placed in an ice storage. A Chain-of-Custody Record is initiated and updated <br /> throughout handling of the samples, and accompanies the samples to the laboratory certified by the <br /> State of California for analyses requested. <br /> _ 1 <br /> A-4 <br />