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Longwall mining of panel 2 (LW-2) passed under Red Wash in September 1988. The <br />surface elevation subsided approximately 3.7 and 4.1 feet at RW-7 and RW-9 respectively. <br />Events in Red Wash over LW-2 were expected to occur in the same fashion as those seen <br />over LW-1. The subsidence trough was developed and any subsequent flow in Red Wash <br />was expected to form a pond. The pond would trap sediments carried in the flow(s) until full, <br />at which time flow in Red Wash would likely resume flowing in a relatively narrow active <br />channel. <br />The conclusions noted above were further confirmed during 1989. On July 29, 1989 a large <br />flow event occurred in Red Wash. The subsidence trough over LW-2 filled with water. The <br />trough over LW-1 also filled, but to a lesser depth as it had filled with sediment in the past. <br />Water level measurements were taken in the monitoring holes while standing water <br />surrounded them. Readings had been taken only 18 days before. Even though the holes <br />were surrounded by standing water (approximately 3 and 4 feet deep at RW-7 and RW-9 <br />respectively) the alluvial water depths had still decreased. <br />Although the purpose of the monitoring program was met, BME continued to monitor the <br />Red Wash alluvial holes until water year 1996-1997. The latest monitoring results are <br />reported in Appendix F and hydrographs for each monitoring hole are presented in Appendix <br />G of the Thirteenth Annual Hydrology Report. <br />12 <br />