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Fall 2017 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />3.0 OTHER SUBSIDENCE MONITORING <br />MCC has been collecting data from numerous monitoring locations in and around Minnesota <br />Reservoir, Monument Dam, and the general Dry Fork area for many years. Ongoing monitoring <br />by MCC personnel includes the Monument Dam and Minnesota Reservoir area, as well as U.S. <br />Forest Service (USFS) roads and stock ponds. Survey data and inspection forms for these areas <br />are provided in Appendix A and B, respectively. Note that the term "displacement," as used in <br />Appendix A, is the difference in the measurements recorded in the last two surveys. An annual <br />aerial photographic comparison of the Minnesota Reservoir/Monument Dam area is conducted <br />each fall to assess movement in the landslides north and south of the reservoir. This discussion <br />and these aerial images are found in Section 3.3 and Appendix C. In addition, MCC monitors <br />USFS water resources in the vicinity of mining and generates an annual report that is included as <br />Appendix D. Also included with this report is a map (Appendix E) that represents the actual <br />extent (as of the date of the map) of the mined E -seam longwall panels within the Maximum <br />Projected Areal Extent of Potential Mineable E -seam as shown on approved Permit Map 51. <br />Data and discussions associated with ongoing MCC monitoring are provided by MCC and <br />included in this WWE report for convenience. <br />3.1 Monument Dam/Minnesota Reservoir Monitoring <br />As described in previous subsidence reports, MCC has conducted monitoring of the Monument <br />Dam and strategic locations around Minnesota Reservoir since 2006. Currently, MCC has <br />monitoring and reporting responsibilities for the land survey stations. Data collected from various <br />monitoring locations on the Monument Dam (including Dam Inspection Forms) are provided in <br />Appendix A. <br />Quarterly land surveys of the monuments (monthly when mining is within one mile of the dam) <br />were completed. A summary of both average height and longitudinal displacement data obtained <br />from spring 2017 to fall 2017 is provided in Table 1 of Appendix A. <br />831-032.799 Wright Water Engineers, Inc. Page 7 <br />February 2018 <br />