2012-05-30_REPORT - C1980007 (8)

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4.4 Subsidence Monitoring of the Dry Fork Road, Channel, and Water Monitoring and Conveyance Structures Beginning in November 2010, numerous monitoring stations were established along the Dry Fork Road on the ground surface above Longwall Panels E2 and E3. These stations will provide a means to collect baseline information before longwall mining and to document the amount of vertical displacement, tilt, and horizontal strain on Dry Fork Road (Appendix E) after longwall mining has been completed. Similarly, MCC has collected required baseline information on water monitoring, conveyance structures (i.e. flumes, culverts, and wells), as well as the thalweg while within the projected angle of draw of longwall panel subsidence (Appendix E). A survey of the deepest part of the Dry Fork stream bed (thalweg), from where the flume crosses Deep Creek to Minnesota Reservoir, was performed for the third time this fall. Data from all three surveys are presented in Appendix E. These surveys also include the invert and outlet elevations on all flumes and corrugated metal pipe culverts along this reach. Appendix E included a comparison of the Northing, Easting, and elevation for each data point within the survey. This comparison reveals changes (some larger than others) that have occurred between surveys. Some of the differences can be accounted for by increased beaver activities, which prevent access to some survey locations, while other differences appear to be the result of continued erosion of the stream channel by natural means. It should also be noted that individual survey markers were not set at each survey station. As a consequence, the second and third surveys attempted to relocate the original survey location using global positional system (GPS) coordinates. In most instances, the second and third survey locations were a reasonable representation of the original. However, the lack of specifically set markers during the original survey accounts for much of the differences represented in the current data. 4.5 Lower Cow Camp 831 - 032.793 May 2012 Fall 2011 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas In compliance with MCC's permit, WEM has documented in detail the original condition of the Lower Cow Camp located on Dry Fork Road prior to subsidence in August 2010, and again twice since that area has been undermined (Appendix F). The structures at Lower Cow Camp Wright Water Engineers, Inc. Page 28