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1 <br />' panel 1 (LW-1). Water levels in the holes were monitored before, during and after active <br />subsidence took place. The purpose of the monitoring program was to determine if surface flow <br />' in Red Wash was being lost to bedrock as the result of subsidence. <br />The monitoring data, anaysis 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 facies (bedrock) and <br />' not from infiltration of surface runoff. <br />• Subsidence cracks in Red Wash as the result of longwall mining are quickly filled <br />with clay and silt preventing loss of surface water flow to bedrock. <br />t 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 RW-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 flows in Red Wash was expected to <br />form a pond. The pond would trap sediments carried in the flow(s) until full, at which time flows <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 while 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 />Again this year, very little change in the water levels was recorded. The rise shown by RW-4 <br />' is likely due to the fact that the casing was bent by someone using it to winch out a stuck vehicle. <br />1 <br />' 14 <br /> <br />