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subsidence took place. The purpose of the monitoring program was to determine H surface flow <br />' in Red Wash was being bst to bedrock as the result of subsidence. <br />The monitoring data, analysis and conclusions reached were submitted to CMLRD in an Interim <br />' Report, November 1987, and in the Third Annual Hydrology Report, January 1988. The purpose <br />of the monitoring program was met in that it was determined that surface flow in Red Wash was <br />not lost to bedrock as a result of subsidence. The major conclusions of the study were: <br />• Recharge of the basal alluvium is from the upper sandstone fades <br />' (bedrock) and not from infiltration of surface runoff. <br />' • Subsidence crad<s in Red Wash as the result of longwall mining are <br />quickly filled with day and silt preventing loss of surface water flow to <br />bedrock. <br />' Although the purpose of the monitoring program has been met, Western Fuels is continuing to <br />monitor the Red Wash alluvial holes. The monitoring results are reported in Appendix F and <br />' hydrographs for each monitoring hole are presented in Appendix G. <br />Longwall mining of panel 2 (LW-2) passed under Red Wash in September 1988. The surface <br />elevation has subsided approximately 3.7 and 4.1 feet at AW-7 and RW-9 respectively. Events <br />in 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 cartied in the flow(s) until toll, at which time flow <br />1 in Red Wash would likely resume flowing in a relatively narow active channel. <br />The conclusions noted above were further confirmed during 1989. On July 29, 1989 a large flow <br />' event occured in Red Wash. The subsidence Vough 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 while they were surounded 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 />Again this year, very little change in the water levels was recorded. <br /> <br /> <br /> <br />16 <br />1 <br />