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solution followed by a triple rinse with deionized water. Each monitoring well will be developed until its discharge is as free as possible of visible sediment. Monitoring Well Purging Prior to well sampling, groundwater will be removed from the well so that a representative sample can be collected from the water-bearing formation. Conductivity, pH, and temperature measurements will be taken during well purging until these parameters stabilize. If the amount of water removed during the purging is equal to or greater than five times the volume of water originally in the well, the well will be sampled immediately after purging. If the amount of water bailed during the purge is less than five times the volume of water in the well, the well will be sampled, provided the conductivity, pH, and temperature have stabilized. Wells that produce a small volume of water will be bailed dry. Sampling will occur when the well has recovered to approximately 80 percent of its original water level. If recovery is insufficient after a four-hour wait, sampling will proceed even if all of the desired samples cannot be collected. To determine the amount of groundwater requiring evacuation, field personnel will: • Measure the inside diameter of the well casing; • Determine the static water level to the nearest one-hundredth of a foot below the measuring point elevation. The top of each well casing will be used as the measuring point and will be marked to standardize its location. The water level indicator will be cleaned before use in each well; • Determine the total depth of the well from the measuring point; • Calculate the number of linear feet of static water (well depth minus the static water level); and • Calculate the vertical column of static water in the well and multiply that amount by 0.65 gallons per foot, which is the amount of water contained in one foot of the four-inch PVC casing. Groundwater Elevation Measurement Prior to well purging and sampling, groundwater levels will be measured relative to the tops of the well casings to an accuracy of 0.01 foot. Potentiometric surface elevations will be calculated by 4-8