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water, and then steam cleaned with deionized water. Any parts that may absorb contaminants, such as plastic pump valves, bladders, etc., will be cleaned as described above or replaced. The inside surfaces of the positive displacement(bladder) pump tubing will be cleaned by heating the tubing overnight at 120°C with a low-flow, inert air source. Once the bladder pump is cleaned and reassembled, a pump blank will be obtained by pumping organic-free water through the bladder pump assembly. The pump effluent will be sampled and analyzed by EPA Method 601. The pump effluent analysis results must be below the method reporting limit for each parameter before the pump is taken to the site for use. During field sampling, equipment surfaces that are placed in the well or contact ground water will be steam cleaned with deionized water before the next well is purged or sampled. Water Level and Total Well Depth Measurements Immediately before a monitoring well is purged, the water level and total well depth will be measured using an electric sounder as described in the previous section "Groundwater Elevation Survey." The electric sounder will be decontaminated by being rinsed with deionized water after each use. Well Purging Before sampling occurs, standing water in the casing and gravel pack will be purged from the monitoring well using a dedicated Well Wizard' bladder pump, pneumatic displacement pump, or Teflon`s bailer. Monitoring wells will be purged according to the protocol presented in Figure A-1. In most monitoring wells, the amount of water purged before sampling will be equal to or greater than four casing volumes. Some monitoring wells are expected to be evacuated to dryness after the removal of less than four casing volumes. These low-yield monitoring wells will be allowed to recharge for up to 24 hours. Samples will be taken as soon as the monitoring wells have recharged to a level sufficient for sample collection. If insufficient water has recharged after 24 hours, the monitoring well will be recorded as dry for the sampling event. Field measurements will be recorded in a waterproof field logbook. Figure A-2 shows an example of the Water Sample Field Data Sheet on which field data are recorded. Field data sheets will be reviewed by the sampling coordinator after the sampling event is completed. The pH, specific conductance, and temperature meter will be calibrated each day before beginning field activities. The calibration will be checked once each day to verify meter performance. Field meter calibrations will be recorded on a Field Data Sheet (see Figure A-2). SAC/pjM939\09390040.gel-95 Ifc:3 A-3 Rev.0 February 14, 1995