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SPRING 2018 SUBSIDENCE AND GEOLOGIC FIELD OBSERVATIONS <br />SOUTH OF DIVIDE AND DRY FORK MINING AREAS <br />1.0 BACKGROUND <br />This subsidence report is the first of two detailed documents on this subject to be generated based <br />on 2018 calendar year observations. These reports of subsidence -related observations at the West <br />Elk Mine have occurred biannually since spring 2007 and annually between 1996 and 2006. In <br />accordance with Mountain Coal Company, LLC's (MCC) Colorado Division of Reclamation, <br />Mining and Safety (CDRMS) permit, these subsidence reports are to be submitted by April 30 (for <br />preceding fall monitoring) and September 30 (for preceding spring monitoring). <br />Prior field observations and experience in the West Elk Mine area over the last twenty-three years 1 <br />(1996 to 2018 inclusive) indicate that subsidence -related features (cracks and bulges) are most <br />visible on roads, well pads, and trails, where the ground is more compact and free of brush. These <br />areas have been, and will continue to be, the focus of the biannual observations to most efficiently <br />obtain subsidence information. Other subsidence features such as rockfalls and landslides are <br />generally observable from overview locations along roads or on well pads and have been, and will <br />continue to be, noted when they occur. <br />Spring 2018 subsidence observations were performed in the South of Divide (SOD) and Dry Fork <br />mining areas with specific focus on the three most recently mined longwall panels (i.e., Longwall <br />Panels E5, E6, and E7). As a result, traverse names used in the previous reports may not coincide <br />with those used in this report. Observations associated with E -seam longwall mining of Panels E 1 <br />through E4 (mined and subsided more than two years previous) can be found in reports prior to <br />2016. Observations of the Apache Rocks and Box Canyon B -seam mining areas are covered in <br />reports prior to 2013. <br />During the spring 2018 field visit, accessible areas within the SOD and Dry Fork mining areas <br />were visited, examined, and photographed to document subsidence -related features observed since <br />' Annual subsidence and geologic hazard reports are kept at Mountain Coal Company, LLC, and at the Colorado <br />Division of Reclamation, Mining and Safety, as well as exhibits to the permit document (Exhibits 60, 60A, 60B, <br />60C, 60D and 60E). <br />831-032.900 Wright Water Engineers, Inc. Page 3 <br />August 2018 <br />