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• GROUND ZERO ANALYSIS,INC. <br /> FIELD PROCEDURES FOR <br /> GROUNDWATER MONITORING AND SAMPLING <br /> Measurement of the Depth to Groundwater in Morutoring Wells <br /> The depth of the groundwater surface in each monitoring well is measured from the top of the well <br /> casing to the nearest 0 01 foot with a Sohnst or similar electric water-level indicator The well is <br /> vented to the atmosphere before obtaining depth-to-water measurements Venting is conducted to <br /> allow the groundwater to equilibrate to barometric pressure These measurements are utilized with <br /> recorded well casing elevations to evaluate the elevation of the groundwater surface in each well and <br /> the slope of the groundwater surface across the site <br /> Sampling of Groundwater Monitonn <br /> The static water level in each well is measured to the nearest 0 01 foot with a Solinst or similar electric <br /> water-level indicator cleaned with a laboratory-grade detergent and deionized water before use in each <br /> well A clean bailer is used to obtain a sample from the surface of the water in the well for subjective <br /> analysis of hydrocarbons, if appropriate The sample is retrieved and examined for floating product, <br /> sheen, color, and clarity <br /> • Approximately 3 to 5 well volumes are purged from each well using a centrifugal pump with '/z-Inch <br /> drip line, a submersible pump, or a Teflon bailer to allow sampling of representative formation water <br /> All downhole equipment/matenals are decontaminated before use in each well The wells are purged <br /> until pH, temperature, and electrical conductivity of the water stabilized, as measured by portable <br /> meters calibrated to a standard buffer and conductivity standard The water level is allowed to recover <br /> to at least 80 percent of the initial water level prior to sampling <br /> A sample of the formation water is then collected from the surface of the water in each of the wells <br /> with a dedicated disposable bailer and slowly transferred using a bottom-emptying device to <br /> laboratory-cleaned sample containers <br /> Equipment Calibration <br /> • Water Level Measurements in Wells (1) Steel surveyors tape Calibration <br /> manufacturer supplied temperature correction will be applied as applicable for field <br /> conditions (2) Electrical well sounders Calibration check against steel surveyor's <br /> tape <br /> • Organic Vapors-Photoionization detector Calibration Daily logged field calibration <br /> using a isobutylene standard as per manufacturer instructions <br /> • <br />