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- GROUNDWATER SAMPLING PROCEDURES <br /> C i men in <br /> All water samples are placed in precleaned laboratory-supplied bottles. Sample bottles <br /> and caps remain sealed until actual usage at the site. All equipment which comes in <br /> contact with the well or groundwater is thoroughly cleaned with a trisodium phosphate <br /> (TSP) solution and rinsed with deionized or distilled water before use at the site. This <br /> cleaning procedure is followed between each well sampled. Wells are sampled in <br /> approximate order of increasing contamination. If a teflon cord is used, the cord is <br /> cleaned. If a nylon or cotton cord is used, a new cord is used in each well All <br /> equipment blanks are collected prior to sampling. The blanks are analyzed periodically <br /> to ensure proper cleaning. <br /> Water Level Measurements <br /> Depth to groundwater is measured in each well using a sealed sampling tape or scaled <br /> electric sounder prior to purging or sampling. If the well is known or suspected of <br /> containing free-phase petroleum hydrocarbons, an optical interface probe is used to <br /> measure the hydrocarbon thickness and groundwater level. Measurements are collected <br /> and recorded to the nearest 0.01 foot. <br /> .�. B it r been h k <br /> If no measurable free-phase petroleum hydrocarbons are detected, a clear acrylic bailer <br /> is used to determine the presence of a sheen. Any observed film as well as odor and <br /> color of the water is recorded. <br /> Groundwater Sam lin <br /> Prior to groundwater sampling, each well is purged of "standing" groundwater. Either <br /> a bailer, hand pump, or submersible pump is used to purge the well. The amount of <br /> purging is dependent on the well yield. In a high yield formation, samples will be <br /> collected when normal field measurement, including temperature, pH, and specific <br /> conductance stabilize, provided a minimum of three well-casing volumes of water have <br /> _. been removed. Field measurements will be taken after purging each well volume. In <br /> low yield formations, the well is purged such that the "standing" water is removed and <br /> -- EXCELTECH, INC. <br /> Groundwater Sampling Protocol <br /> Latest Revision: March 28, 1990 <br />