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Water Level and Total Well Depth Measurements <br />Immediately before a monitoring well is purged, the water level and total well depth will <br />be measured using an electric sounder as described in the previous section "Groundwater <br />Elevation Survey." The electric sounder will be decontaminated by being rinsed with <br />deionized water after each use. <br />Before sampling occurs, standing water in the casing and gravel pack will be purged from <br />the monitoring well using a dedicated Well Wizard purging and sampling system, a <br />polyvinyl chloride or Teflon° bailer, or a submersible pump. Monitoring wells will be <br />purged according to the protocol presented in Figure D-1. In most monitoring wells, the <br />amount of water purged before sampling will be equal to or greater than four casing <br />volumes. Some monitoring wells are expected to be evacuated to dryness after the <br />removal of less than four casing volumes. These low -yield monitoring wells will be <br />allowed to recharge for up to 24 hours. Samples will be obtained as soon as the <br />monitoring wells have recharged to a level sufficient for sample collection. If insufficient <br />water has recharged after 24 hours, the monitoring well will be recorded as dry for the <br />sampling event. <br />Field measurements will be recorded in a water resistant field logbook. Figure D-2 shows <br />an example of the Water Sample Field Data Sheet on which field data are recorded. Field <br />data sheets will be reviewed by the sampling coordinator after the sampling event is <br />® completed. <br />The pH, specific conductance, and temperature meter will be calibrated each day before <br />beginning field activities. The calibration will be checked once each day to verify meter <br />performance. Field meter calibrations will be recorded on the Water Sample Field Data <br />Sheet (see Figure D-2). <br />Well Sampling <br />A Teflon bailer or the dedicated Well Wizard bladder pump will be the only equipment <br />acceptable for well sampling. When samples for volatile organic analysis are being <br />collected, the pump or bailer effluent will be slowed to minimize turbulence and aeration. <br />Glass bottles of at least 40 milliliters volume and fitted with Teflon -lined septa will be used <br />in sampling for volatile organics. These bottles will be filled completely to prevent air from <br />remaining in the bottle. A positive meniscus forms when the bottle is completely full. A <br />SAC\N NPJM3M390031.9BG-94 sdg:4 D-3 Rev. 0, 4/20/95 <br />