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development. After the wells stabilize for a minimum of 24 hours, the wells are purged of <br /> stagnant water and a sample is collected for laboratory analysis See the section on groundwater <br /> sampling. <br /> Subjective An 1 s1s of Groundwater Sam le <br /> Groundwater samples are collected for subjective analysis from just below the air-fluid interface <br /> in a monitoring well by lowering approximately half the length of a clean bailer through the <br /> interface The bailer is retrieved and the water sample examined for floating product, sheen, <br /> or other subjective evidence of hydrocarbons. <br /> Measurement of the Depth to Groundwater in Monitoring Wells <br /> The depth of the groundwater surface in a monitoring well is measured from the top of the well <br /> casing to the nearest 0 01 foot with a Solinst or similar electric water-level indicator. The well <br /> will be vented to the atmosphere before obtaining depth-to-water measurements. Venting is <br /> conducted to allow the groundwater to equilibrate to barometric pressure. These measurements <br /> will be combined to evaluate the elevation of the groundwater surface in each well and the slope <br /> of the groundwater surface across the site. <br /> Groundwater Sampling <br /> The static water level in each well is measured to the nearest 0.01 foot with a Solinst or similar <br /> . electric water-level indicator cleaned with a laboratory-grade detergent and deionized water <br /> before use in each well A clean bailer is used to obtain a sample from the surface of the water <br /> in the well for subjective analysis of hydrocarbons The sample is retrieved and examined for <br /> floating product, sheen, color, and clarity. <br /> Approximately 3 to 5 well volumes are purged from each well with a stainless-steel electrical <br /> submersible pump to allow sampling of representative formation water. The pump, cables, and <br /> hoses are cleaned with a laboratory-grade non-phosphatic detergent and water before use in each <br /> well. The wells are purged until Ph, temperature, and electrical conductivity of the water <br /> stabilized, as measured by portable meters calibrated to a standard buffer and conductivity <br /> standard The water level is allowed to recover to at least 80 percent of the initial water level. <br /> A sample of the formation water then is collected from the surface of the water in each of the <br /> wells with a dedicated disposable bailer and slowly transferred to laboratory-cleaned sample <br /> containers The recovered fluids from sampling in each well are directed into 55-gallon liquid <br /> waste drums approved for this use by the Department of Transportation until suitable disposal <br /> options are selected based on analytical results Disposal of water at an appropriate disposal <br /> facility is the responsibility of the client. <br /> Water Sample-Labeling and Handling <br />. R-081694 nD 3 <br />