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` SJi <br /> FEELD PROCEDURES <br /> Measurement of the Depth to Groundwater in Monitoring 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 combined to <br /> evaluate the elevation of the groundwater surface in each well and the slope of the groundwater surface <br /> across the site <br /> Sampling of Groundwater Monitoring Wells <br /> The static water level in each well is measured to the nearest 0 01 foot with a Sohnst or surnlar 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 The sample is retrieved and examined for floating product, sheen, color, and <br /> clarity A Photoionization Detector(PID) is also used to screen groundwater removed from each well <br /> for the presence of hydrocarbons <br /> Approximately 3 to 5 well volumes are purged from each well using a centrifugal or submersible pump <br /> to allow sampling of representative formation water All downhole piping and tubing are <br /> decontaminated before use in each well The wells are purged until pH, temperature, and electrical <br /> conductivity of the water stabilized, as measured by portable meters calibrated to a standard buffer and <br /> conductivity standard The water level is allowed to recover to at least 80 percent of the initial water <br /> 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 to laboratory-cleaned sample containers <br /> Equipment_Calibration <br /> • Water Level Measurements in Wells-Steel surveyors tape Calibration manufacturer <br /> supplied temperature correction will be applied as applicable for field conditions <br /> Electrical well sounders Calibration check against steel surveyor's tape <br /> • Organic Vapors-Photoionization detector Calibration Day logged field calibration <br /> using a isobutylene standard as per manufacturer instructions <br /> • Groundwater pH Measurements-Digital pH meter Calibration standard pH solutions <br /> of 4,7, and 10 utilized for daily logged field calibration according to manufacturer <br /> instructions <br />