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Fall 2016 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mininq Areas <br />2.0 GENERAL SUBSIDENCE OBSERVATION AND REPORTING <br />On October 7, 2016, Wright Water Engineers, Inc. (WWE) made an attempt to observed <br />subsidence and geologic field conditions of the SOD and Dry Fork mining areas (consistent with <br />current Exhibit 60E) for MCC. A precipitation event two days prior to the site visit left portions <br />of the field work area difficult to observe due to muddy and slick conditions. As a result, WWE <br />returned on October 9, 2016 to complete the observations after conditions had dried out <br />substantially. <br />Based on field observations from 1996 to fall 2016, the effects of longwall mining above the West <br />Elk Mine have been less than initially projected as reported in Exhibit 60 (Dunrud, 1998 rev.) and <br />60E (WWE, 2012). Rockfalls and/or landslides have generally been observed only sporadically <br />in the Box Canyon mining area since 2006 where the steep, upper reaches of Sylvester Gulch and <br />Box Canyon abut the large geographic feature known as West Flatiron. In the flatter and more <br />rounded topography of the Apache Rocks, SOD, and Dry Fork mining areas, the rockfall and <br />landslide potential is much smaller. However, subsidence -related tension cracks have occurred in <br />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 fall 2016 field <br />visit (October 9), mining was complete in E -seam Longwall Panels E1, E2, E3, E4, and E5. <br />Mining of Longwall Panel E6 was initiated in September 2015 and was approaching 50% <br />completion as of the time of our fall 2016 field visit. <br />Beginning with the Spring 2011 Subsidence Report, an effort was made to reduce the size of the <br />semi-annual subsidence reports by eliminating much of the regularly included background and <br />historical information (e.g., subsidence projections). For this reason, specific details associated <br />with subsidence projections and field recognition of subsidence and non -subsidence features were <br />eliminated. Since that time, readers have been directed to Section 1.0 and 2.0, respectively, of the <br />Spring 2011 Subsidence Report and to Exhibits 60 and 60E of the West Elk Mine permit for this <br />information. <br />831-032.798 Wright Water Engineers, Inc. Page 5 <br />January 2017 <br />