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purged according to the protocol presented in Figure A-1. In most moni- toring wells, the amount of water purged before sampling was equal to or greater than four casing volumes. Some monitoring wells were evacuated to dryness after the removal of less than four casing volumes. These low- yield monitoring wells were allowed to recharge for up to 24 hours. Samp- les were collected as soon as the monitoring wells had recharged to a level sufficient for sample collection. If insufficient water had recharged after 24 hours, the monitoring well was recorded as dry for the sampling event. Field measurements were recorded in a water-resistant field logbook. Fig- ure A-2 shows an example of the Water Sample Field Data Sheet on which field data were recorded. Field data sheets were reviewed by the sampling coordinator after the sampling event was completed. The pH, specific conductance, and temperature meter were calibrated each day before beginning field activities. The calibration was checked once each day to verify meter performance. Field meter calibrations were recorded on a Field Data Sheet (see Figure A-2). Well Sampling Teflon bailer or bladder pump was the only equipment acceptable for well sampling. When samples for volatile organic analysis were being col- lected with a bladder pump, the pump flow was regulated to approximately 100 milliliters per minute to minimize pump effluent turbulence and aera- tion. Glass bottles of at least 40 milliliters volume and fitted with Teflon- lined septa were used in sampling for volatile organics. These bottles were filled completely to prevent air from remaining in the bottle. A positive meniscus formed when the bottle was completely full. A convex Teflon septum was placed over the positive meniscus to eliminate air. After the bottle was capped, it was inverted and tapped to verify that it contained no air bubbles. The sample containers for other parameters were filled, fil- tered as required, and capped. To determine dissolved concentrations of metals, appropriate field filtration techniques were used. When a Teflon bailer was used, the sample was filtered by emptying the contents of the bailer into a pressure transfer ves- sel. A disposable 0.45-micron acrylic copolymer filter was threaded onto the transfer vessel at the discharge point and the vessel was sealed. Pressure was applied to the vessel with a hand pump and the filtrate was pj9\939\9390111 c A-4 Rev. 0 September 9, 1992