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Fall 2013 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />historic standpipe piezometers, four boring locations each with three nested piezometers, two <br />inclinometer locations (one on the dam and one in the landslide area south of the dam), and <br />numerous survey mirrors for evaluation of surface movement on and near the dam. Many of these <br />locations have been monitored monthly from July 2006, while others were added to the monitoring <br />network during 2007 and 2008. Beginning in spring 2010, the Minnesota Canal and Reservoir <br />Company took over the monitoring and reporting responsibilities for the piezometers and <br />inclinometers on Monument Dam per their agreement with. MCC and the Colorado State <br />Engineer's Office (SEO). MCC retained monitoring and reporting responsibilities for the land <br />survey stations. Data collected from various monitoring locations on the Monument Dam <br />(including Dam Inspection Forms) are provided in Appendix B. <br />As discussed in previous reports, the Minnesota Reservoir Robotic Total Station (RTS) became <br />completely inoperable in 2011 and could not be repaired after numerous attempts. In lieu of the <br />RTS, quarterly land surveys (monthly when mining is within one mile of the dam) of the <br />monuments are completed. A summary of both average height and longitudinal displacement data <br />obtained from spring 2013 to fall 2013 is provided in Table 1 as 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 south <br />of Minnesota Reservoir. Annual comparisons are performed using July 2004 photographs as a <br />baseline reference. Appendix C of this report includes the July 2004 baseline photograph (Map <br />C -1), as well as a photograph of the same area taken in June 2012 (Map C -6), and May 2013 (Map <br />C -7). For brevity, Maps C -2 (September 2008), C -3 (June 2009), C -4 (May 2010) and C -5 (May <br />2011) are not included herein but can be found in the previous fall reports. The May 2013 aerial <br />image (Map C -7) reveals the area where a french drain was installed south of the Monument Dam <br />south abutment in early fall 2009 to remove water from the upper end of the existing slide complex. <br />The June 2012 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 and May <br />2013, except in the area south of the south abutment of Monument Dam. Other noted differences <br />appear to be explained by the location of shadows at the time of day in which the image was <br />obtained. <br />831 - 032.795 Wright Water Engineers, Inc. Page 26 <br />January 2014 <br />