2013-04-25_REPORT - C1980007 (9)

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831 - 032.794 April 2013 Fall 2012 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas 4.0 OTHER SUBSIDENCE - RELATED DATA In addition to the semi - annual traverses conducted by WWE above longwall mining areas, MCC has been collecting data from numerous other monitoring locations. For example, regular inspections of USFS roads and stock ponds were completed by MCC personnel. Copies of these inspection forms can be found in Appendix A. MCC also collected substantial information from the vicinity of Minnesota Reservoir and Monument Dam, such as visual inspections, survey data, piezometer and inclinometer data, and annual aerial photo comparisons (Appendices B and C). In addition, MCC monitored USFS water resources (Appendix D), Dry Fork Road survey data (Appendix E); Dry Fork channel survey data which includes culverts, flumes, well and thalweg survey data of all water conveyance structures over the Dry Fork Lease (Appendix E); and the Lower Cow Camp Subsidence Survey Data (Appendix F). Also included is a map (Appendix G) of the actual extent (as of the date of the map) of the mined E -seam longwall panels within the Maximum Projected Areal Extent of Potential Mineable E -seam as shown on approved Permit Map 51. Within these appendices. note that the term "recent displacement" indicates that the displacement shown is the difference in the measurements recorded in the last two surveys. A general discussion of the Minnesota Reservoir and Monument Dam follows in Section 4.1 with the actual data provided in Appendix B. An annual aerial photographic comparison of the Minnesota Reservoir /Monument Dam area is conducted each fall to assess movement in the landslides north and south of the reservoir. This discussion and these aerial images are found in Section 4.2 and Appendix C. Section 4.3 discusses the 2012 Water Resources Project Survey Report for the USFS as required in the permit and included as Appendix D. Additional details regarding the monitoring of Dry Fork Road subsidence, Dry Fork channel survey data across the Dry Fork Lease, and the Dry Fork Thalweg can be found in Section 4.4 and Appendix E, while monitoring of the Lower Cow Camp is discussed in Section 4.5 with corresponding data in Appendix F. Data and discussions associated with this section (excluding Section 4.2 and Appendix C) are the responsibility of MCC and is provided in this WWE report for convenience. Wright Water Engineers, Inc. Page 28