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$ <br />Equipment Cleaning <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 />Bailer Sheen Check <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 Sampling <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 />