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Spring 2011 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />angle of draw is an appropriate value for use in the SOD and Dry Fork mining areas relative to E- <br />seam mining. A memorandum outlining this analysis and conclusion can be found in Appendix <br />B of this report along with Map B -1 showing the 120 survey monuments associated with the <br />subsidence monitoring grid. <br />MCC has been collecting data from numerous monitoring locations in and around Minnesota <br />Reservoir and Monument Dam for the last several years. A general discussion of the data <br />collected to date is provided in Section 3.1 with the specific data provided in Appendix C. In <br />addition, regular inspections of U.S. Forest Service roads and stock ponds are completed by <br />MCC personnel (Appendix D). Ongoing subsidence survey data from the Dry Fork channel <br />(Appendix E) and the Lower Cow Camp (Appendix F) are also provided with this report. Data <br />and discussions associated with Section 3.1 and Appendices C -F are the responsibility of MCC <br />and provided in this WWE report for convenience. <br />3.1 Monument Dam /Minnesota Reservoir Monitoring Data <br />Beginning in 2006, numerous monitoring stations were established on Monument Dam and at <br />strategic locations around Minnesota Reservoir as a means to collect baseline information about <br />water levels and potential surface /subsurface movement. Monitoring locations include three <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 <br />these locations have been monitored monthly from July 2006, while others were added to the <br />monitoring network during 2007 and 2008. Beginning in the spring 2010, the Minnesota Canal <br />and Reservoir Company took over the monitoring and reporting responsibilities for the <br />piezometers and inclinometers on Monument Dam per their agreement with MCC and the State <br />Engineer's Office. MCC retained monitoring and reporting responsibilities for the land survey <br />stations. Data collected from various monitoring locations on the Monument Dam (including <br />Dam Inspection Forms) are provided in Appendix C. <br />831 - 032.793 <br />September 2011 <br />Wright Water Engineers, Inc. Page 11 <br />