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831 - 032.794 <br />April 2013 <br />Fall 2012 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />As reported in the Spring 2012 Report, from January to June 2012, there was no significant <br />movement measured on the dam. For the July to December 2012 time period, all of the changes <br />in the Easting direction (± 0 -0.31 inches), Northing direction (± 0 -0.83 inches) and in elevation <br />(± 0 -0.10 inches) for all monuments on the dam and Borrow Area were insignificant <br />(approximately <0.5 feet). Based on visual observations, little to no change has been observed <br />on Monument Dam and Borrow Area (see Monument Dam Inspection Reports included in <br />Appendix B). <br />4.2 Monument Dam /Minnesota Reservoir Aerial Photograph Comparison <br />Each year, MCC performs an aerial photographic survey of the landslides located north and <br />south of Minnesota Reservoir. Annual comparisons are performed using July 2004 photographs <br />as a baseline reference. Appendix C of this report includes the July 2004 baseline photograph <br />(Map C -1), as well as a photograph of the same area taken in September 2008 (Map C -2), June <br />2009 (Map C -3), May 2010 (Map C -4), June 2011 (Map C -5) and June 2012 (Map C -6). For <br />brevity, Maps C -2 (September 2008), C -3 (June 2009) and C -5 (May 2010) are not included <br />herein but can be found in the Fall 2011 Report. The June 2012 aerial image (Map C -6) <br />continues to show the area where a french drain was installed south of the Monument Dam south <br />abutment in early fall 2009 to remove water from the upper end of the existing slide complex. <br />The June 2011 image is provided as the most recent image for comparative purposes. A <br />comparison of photographs finds there to be relatively little change between June 2009, June <br />2011 and June 2012, except in the area south of the south abutment of Monument Dam. Other <br />noted differences appear to be explained by the location of shadows at the time of day in which <br />the image was obtained. <br />As of the time of the 2012 aerial photograph (June), mining of E -seam Panel El and E2 were <br />complete and E -seam Panel E3 was nearing completion with mining progressing from southeast <br />to northwest. <br />Wright Water Engineers, Inc. Page 30 <br />