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Spring 2017 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />2.0 GENERAL SUBSIDENCE OBSERVATION AND REPORTING <br />On June 16, 2017, Wright Water Engineers, Inc. (WWE) observed subsidence and geologic field <br />conditions of the SOD and Dry Fork mining areas (consistent with current Exhibit 60E) for MCC. <br />Similar observations at the West Elk Mine have been made annually since 1996 and semi-annually <br />since 2007 as a means to assess potential longwall mining effects on the environment. <br />Based on field observations from 1996 to spring 2017, the effects of longwall mining above the <br />West Elk Mine have been less than initially projected as reported in Exhibit 60 (Dumud, 1998 <br />rev.) and 60E (WWE, 2012). Rockfalls and/or landslides have generally been observed only <br />sporadically in the Box Canyon mining area since 2006 where the steep, upper reaches of Sylvester <br />Gulch and Box Canyon abut the large geographic feature known as West Flatiron. In the flatter <br />and more rounded topography of the Apache Rocks, SOD, and Dry Fork mining areas, the rockfall <br />and landslide potential is much smaller. However, subsidence -related tension cracks have <br />occurred in these mining areas, particularly above the active longwall mining face. <br />E -seam longwall mining in the SOD mining area was initiated on Panel E1 in December 2008 <br />beginning at the east end and progressing westward. All mining in the SOD mining area is planned <br />to progress from the east end of the panels toward the west. As of the time of our spring 2017 field <br />visit (June 16), mining was complete in E -seam Longwall Panels E1, E2, E3, E4, and E5. Mining <br />of Longwall Panel E6 was initiated in September 2015 and was more than 95 percent complete at <br />the time of our spring 2017 field visit. <br />Beginning with the Spring 2011 Subsidence Report, an effort was made to reduce the size of the <br />semi-annual reports by eliminating much of the background and historical information (e.g., <br />subsidence projections) included in the previous reports. For this reason, specific details <br />associated with subsidence projections and field recognition of subsidence and non -subsidence <br />features were eliminated. Since that time, readers have been directed to Section 1.0 and 2.0, <br />respectively, of the Spring 2011 Subsidence Report and to Exhibits 60 and 60E of the West Elk <br />Mine permit for this information. <br />Also in keeping with the goal of a reduction in report size, future reports will focus on the <br />identification and discussion of those observations that reflect an obvious change in the conditions <br />831-032.799 Wright Water Engineers, Inc. Page 5 <br />August 2017 <br />