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Spring 2009 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />December's data set for each monument are considered negligible and a difference of zero was <br />• input into the table. Monuments with a displacement between December and June greater than <br />0.5 feet, and not within one standard deviation, were considered to have incurred "significant <br />movement" and were field verified. Those differences greater than one standard deviation but <br />less than 0.5 feet were considered "insignificant movement" of a "minor change". <br />There was no significant movement measured on the dam from December 2008 to June 2009. <br />There were two survey monuments that indicated significant movement on the landslide area <br />south of the dam. These were survey points 7003 and 7021. A visual inspection verified that <br />some movement had taken place, but did not appear to be to the degree indicated in the <br />longitudinal measurements recorded. These monuments are located in a pre-existing, active <br />slide area and have likely experienced some additional settling after the initial slump occurred in <br />2008. Since the remaining monuments showed no signs of movement, it can be assumed that <br />this displacement was an isolated activity likely contained within the landslide body. <br />It should be noted that MCC's obligation to conduct aerial photographic surveys of the <br />• landslides located north and south of Minnesota Reservoir using July 2004 photographs as a <br />baseline reference is required on an annual basis and will be reported in the fall 2009 subsidence <br />report. To date, photographic comparisons have shown there to be no observable difference in <br />the subject slide areas with the obvious exception of the earthwork conducted on the south side <br />of Monument Dam where considerable materials were removed to buttress the downstream <br />portion of the dam and readjust/rebalance the toe load of the landslide. <br />3.3 B-Seam Survey Information of Panel 25 <br />?J <br />Also. included in this report is a comparison of survey data from select locations in Sylvester <br />Gulch overlying B-seam longwall Panel 25. Survey data included in Appendix D is from seven <br />locations surveyed pre (July 2008), during (December 2008), and post (May 2009) mining. An <br />elevation comparison between the pre and post mining surveys show that there was between 0.1 <br />and 7.0 feet of change during the observation periods. <br />831-032.791 Wright Water Engineers, Inc. Page 13 <br />November 2009