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GENERAL FIELD PROCEDURES <br /> General field procedures used during fluid level monitoring and ground water sampling activities <br /> are described below. <br /> FLUID LEVEL MONITORING <br /> Fluid levels are monitored in the wells using an electronic interface probe with conductance <br /> sensors. The presence of liquid-phase hydrocarbons is verified using a hydrocarbon-reactive <br /> paste. The depth to liquid-phase hydrocarbons and water is measured relative to the well box <br /> top or top of casing. Well box or casing elevations are surveyed to within 0.02 foot relative to <br /> a county or city bench mark. <br /> GROUND WATER SAMPLING <br /> Ground water monitoring wells are purged and sampled in accordance with standard regulatory <br /> protocol. Typically, monitoring wells that contain no liquid-phase hydrocarbons are purged of <br /> ground water prior to sampling so that fluids sampled are representative of fluids within the <br /> formation. Temperature, pH, and specific conductance are typically measured after each well <br /> casing volume has been removed. Purging is considered complete when these parameters vary <br /> less than 10% from the previous readings, or when four casing volumes of fluid have been <br /> removed. Samples are collected without further purging if the well does not recharge within <br /> 2 hours to 80% of its volume before purging. <br /> The purged water is either pumped directly into a licensed vacuum truck or temporarily stored <br /> in labeled drums prior to transport to an appropriate treatment or recycling facility. If an <br /> automatic recovery system (ARS) is operating at the site, purged water may be pumped into the <br /> ARS for treatment. <br /> Ground water samples are collected by lowering a 1.5-inch-diameter, bottom-fill, disposable <br /> polyethylene bailer just below the static water level in the well. The samples are carefully <br /> transferred from the check-valve-equipped bailer to I-liter and 40-milliliter glass containers. The <br /> sample containers are filled to zero headspace and fitted with Teflon-sealed caps. Each sample <br /> is labeled with the project number, well number, sample date, and sampler's initials. Samples <br /> remain chilled at approximately 4°C prior to analysis by a state-certified laboratory. <br /> GF_NFLD.2.-4123/93 <br />