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1 <br />Longwall mining of panel 2 (LW-2) passed under Red Wash in September 1988, The surface <br />' elevation subsided approximately 3.7 and 4.1 feet at RW-7 and RW-9 respectively. Events in <br />Red Wash over LW-2 were expected to occur in the same fashion as those seen over LW-1. <br />' The subsidence trough was developed and any subsequent flow in Red Wash was expected to <br />form a pond. The pond would trap sediments carried in the flow(s) until Tull, at which time flow <br />in Red Wash would likely resume flowing in a relatively narrow active channel. <br />The conclusions noted above were further confirmed during 1989. On July 29, 1989 a large flow <br />event occurred in Red Wash. The subsidence trough over LW-2 filled with water. The trough <br />' over LW-1 also filled, but to a lesser depth as it had filled with sediment in the past. Water level <br />measurements were taken in the monitoring holes white they were surrounded by standing water. <br />' Readings had been taken only 18 days before. Even though the holes were surrounded by <br />standing water (approximately 3 and 4 feet deep at RW-7 and RW-9 respectively) the alluvial <br />water depths had still decreased. <br /> <br />1 <br />1 <br />I <br /> <br /> <br />1 <br /> <br /> <br />1 <br />1 <br />17 <br />