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- <br /> GENERAL FIELD PROCEDURES <br /> General field procedures used during fluid-level monitoring and groundwater sampling activities are <br /> described below. <br /> FLUID-LEVEL MONITORING <br /> Fluid-levels are monitored in the wells using an electronic interface probe with conductance sensors. The <br /> presence of liquid-phase hydrocarbons is verified using a hydrocarbon-reactive paste. The depth to liquid- <br /> phase hydrocarbons and water is measured relative to the well box top or top of casing. Well box or <br /> casing elevations are surveyed to within 0.02 foot relative to a county or city bench mark. <br /> GROUNDWATER SAMPLING <br /> Groundwater monitoring wells are purged and sampled in accordance with standard regulatory protocol. <br /> Typically, monitoring wells that contain no liquid-phase hydrocarbons are purged of groundwater prior <br /> to sampling so that fluids sampled are representative of fluids within the formation. Temperature, pH, <br /> and specific conductance are typically measured after each well casing volume has been removed. <br /> Purging is considered complete when these parameters vary less than 10% from the previous readings, <br /> or when four casing volumes of fluid have been removed. Samples are collected without further purging <br /> if the well does not recharge within 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 in labeled <br /> drums prior to transport to an appropriate treatment or recycling facility. If an automatic recovery system <br /> (ARS) is operating at the site, purged water may be pumped into the ARS for treatment. <br /> Groundwater samples are collected by lowering a 1.5-inch-diameter, bottom-fill, disposable polyethylene <br /> bailer just below the static water level in the well. The samples are carefully transferred from the check- <br /> valve-equipped bailer to 1-liter and 40-milliliter glass containers. The sample containers are filled to zero <br /> headspace and fitted with Teflon-sealed caps. Each sample is labeled with the project number, well <br /> number, sample date, and sampler's initials. Samples remain chilled at approximately 4°C prior to <br /> analysis by a state-certified Iaboratory. <br /> i <br />