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the formation cannot be entirely eliminated by well development. After the wells have been <br /> adequately developed, a sample is collected for laboratory analysis. <br /> Subjective Analysis of Groundwater Samples <br /> Groundwater samples are collected for subjective analysis from just below the air-fluid <br /> interface in a monitoring well by lowering approximately half the length of a clean bailer <br /> through the interface. The bailer is retrieved and the water sample examined for floating <br /> product, sheen, 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 <br /> well casing to the nearest 0.01 foot with a Solinst or similar electric water-level indicator. The <br /> well is vented to the atmosphere before obtaining depth-to-water measurements. Venting is <br /> conducted to allow the groundwater to equilibrate to barometric pressure. These <br /> measurements are combined to evaluate the elevation of the groundwater surface in each well <br /> and the slope 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 non-phosphate detergent and <br /> clean tap or deionized water before use in each well. A clean bailer is used to obtain a sample <br /> from the surface of the water in the well for subjective analysis of hydrocarbons. The sample <br /> is retrieved and examined for floating product, sheen, color, and clarity. <br /> Approximately 3 to 5 well volumes are purged from each well with a pre-washed submersible <br /> pump or bailer to allow sampling of representative formation water. All down hole equipment <br /> is cleaned with a laboratory-grade non-phosphate detergent and water before use in each well. <br /> The wells are purged until pH, temperature, and electrical conductivity of the water have <br /> stabilized, as measured by portable meters calibrated to a standard buffer and conductivity <br /> standard. If the well is pumped or bailed dry during purging, the water level is allowed to <br /> recover to at least 80 percent of the initial water level prior to sampling. <br /> A sample of the formation water then is retrieved 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 DOT until suitable disposal options are selected <br /> based on analytical results. Disposal of water at an appropriate disposal facility is the <br /> responsibility of the client. <br /> SHELLS\FLDMTHDS.doc 3 <br />