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April 20, 1990 <br /> SAMPLE COLLECTION <br /> This section describes the routine procedures followed by G-R while <br /> collecting ground-water samples for chemical analysis. These <br /> procedures include decontamination, water-level measurements, well <br /> purging, physical parameter measurements, sample collection, sample <br /> preservation, sample handling, and sample documentation. Critical <br /> sampling objectives for G-R are to: <br /> 1. Collect ground-water samples that are <br /> representative of the sampled matrix and, <br /> 2. Maintain sample integrity from the time of sample <br /> collection to receipt by the analytical <br /> laboratory. <br /> Sample analyses methods, containers, preservation, and holding times <br /> are presented in Table 1. <br /> Decontamination Procedures <br /> �. All physical parameter measuring and sampling equipment are <br /> decontaminated prior to sample collection using Alconox or equivalent <br /> detergent followed by steam cleaning with deionized water. Any <br /> sampling equipment surfaces or parts that might absorb specific <br /> contaminants, such as plastic pump valves, impellers, etc., are <br /> cleaned in the same manner. <br /> .. Sample bottles, bottle caps, and septa used for sampling volatile <br /> organics are thoroughly cleaned and prepared in the laboratory. <br /> Sample bottles, bottle caps, and septa are protected from all <br /> potential chemical contact before actual usage at a sample location. <br /> During field sampling, equipment placed in a well are decontaminated <br /> before purging or sampling the next well. The equipment are <br /> decontaminated by cleaning with Alconox or equivalent detergent <br /> followed by steam cleaning with deionized water. <br /> Water-Level Measurements <br /> Prior to purging and sampling a well, the static-water levels are <br /> measured in all wells at a project site using an electric sounder <br /> and/or calibrated portable oil-water interface probe (Figure 4). Both <br /> static water-level and separate-phase product thickness are measured <br /> to the nearest ±0.01 foot. The presence of separate-phase product is <br /> confirmed using a clean, acrylic or polyvinylchloride (PVC) bailer, <br /> measured to the nearest ±0.01 foot with a decimal scale tape. <br /> YtIeffler — ryan inc. (415>7r83-7500 Page 12 <br /> general and mironmenla) conlraclors <br />