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Figures 7 and 8 illustrate the present seasonal variation in flow from the Terry Tunnel. Flow <br /> from the Terry Tunnel is measured with an "H" flume below the settling ponds. Flow <br /> measurements from 1988 through fall of 1990 may be somewhat underestimated due to pond <br /> leakage (which is now insignifAcant) and inadequate leveling of the flume. No measurements <br /> are taken during winter and spring because the access road to the Terry Tunnel is typically <br /> impassible until late May. Figure 7 shows a peak flow in early June, but it is possible that the <br /> peak flow may have occurred prior to the first gauging in some prior years. <br /> i <br /> Flow from the American Tunnel is much more constant than flow from the Terry Tunnel. <br /> Figure 9 is a hydrograph of flow rates from the American Tunnel as measured using a Parshall <br /> flume downstream of the settling ponds at Gladstone. Flows less than 1.8 million gallons per <br /> day (mgd) or greater than 2.6 mgd are probably caused by pond cleaning activities. Flow rate <br /> from the American Tunnel is relatively constant throughout the year because the overwhelming <br /> majority of the flow originates ground-water discharge (from fractures), rather than as surface <br /> drainage into the mine workings. <br /> Flow measurements with a pygmy meter at the lime treatment plant just downstream of the <br /> portal of the American Tunnel (Table 3) shows a flow rate approximately 35% greater than the <br /> flow rate below the settling ponds (Figure 9). The reason for the difference is presently under <br /> investigation by SJCMV. <br /> sanjuan\sunny\110361\oc191.Rpl 36 <br /> aOR simon o o����� <br /> c H <br />