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SPRING 2012 SUBSIDENCE AND GEOLOGIC FIELD OBSERVATIONS <br />BOX CANYON, APACHE ROCKS, <br />AND SOUTH OF DIVIDE MINING AREAS <br />1.0 SUMMARY OF FINDINGS <br />On May 31 and June 1, 2012, Wright Water Engineers, Inc. (WWE) performed subsidence and <br />geologic field investigations of Box Canyon, Apache Rocks, South of Divide (SOD), and Dry <br />Fork mining areas for Mountain Coal Company, LLC (MCC). These observations have been <br />made annually since 1996 and semi - annually since 2007. <br />Based on field observations from 1996 to spring 2012, the effects of longwall mining in the <br />Apache Rocks and Box Canyon mining areas have been less than were initially projected as <br />reported in Exhibit 60 (Dunrud 1998 rev.). Specific details about these projections are generally <br />outlined in Section 1.0 of the Spring 2011 Subsidence Report and in Exhibit 60 of the West Elk <br />Mine permit. Additional background information such as field recognition of subsidence and <br />non - subsidence features can also be found in Section 2.0 of the Spring 2011 Subsidence Report. <br />To date, no mining effects on rockfalls or landslides have been observed in the Apache Rocks <br />mining area. Sporadic rockfalls and landslides have been observed in the Box Canyon mining <br />area (B -seam longwall mining) since 2006 where the steep, upper reaches of Sylvester Gulch and <br />Box Canyon abut West Flatiron. Since 2009, the area has stabilized considerably. Aside from a <br />few remaining MDW pads near the north end of West Flatiron, mining - related activities in this <br />area are complete. Nonetheless, the potential for more cracking and rockfall activity on the west - <br />and east - facing cliffs of West Flatiron remains moderate to high. <br />During the spring 2012 field traverses, no subsidence tension cracks, compression bulges, or <br />other related features were observed in the surficial deposits (colluvium and local alluvium) <br />above mined B -seam Longwall Panels 14 to 25 in the Apache Rocks, and Box Canyon mining <br />areas. Subsidence - related tension cracks were observed in the SOD along US Forest Service <br />Road 711 (Dry Fork Road) and along Traverse K1 -K1' (an MDW pad access road) above areas <br />831 - 032.794 <br />November 2012 <br />Wright Water Engineers, Inc. Page 1 <br />