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EXHIBIT 60B SUBSIDENCE EVALUATION FOR THE SOUTH OF DIVIDE MINING AREA 1.0 INTRODUCTION This exhibit describes subsidence processes that have been observed by the author and others from studies above longwall mining panels in Mountain Coal Company's (MCC) West Elk Mine and from other similaz operations and studies. The subsidence information obtained from the current West Elk Mine azea is used in this application to project subsidence processes, amounts, and effects to the South of Divide mining azea. This application document is intended to comply with the Colorado Division of Minerals and Geology (CDMG) Regulations for Coal Mining, revised June 26, 2002, under Section 2.05.6, Mitigation of the Impacts of Mining Operations. 2.0 MINING METHOD The longwall mining method will be utilized in the South of Divide mining azea. The planned . panel design is similaz to the B Seam West Elk Mine longwall panels where subsidence measurements were used to obtain the baseline data that will be used in this report. A range of 8 to 14 feet of coal will be extracted from the E Seam (Figure 1). The extraction thicknesses aze projected based on exploration hole data; actual thicknesses may vary depending oa mining conditions encountered Longwall panels El through E8 aze projected to be 1,080 feet wide and range from about 9,000 to 11,000 feet long (without the Dry Fork Lease included). Panel E9 is projected to be 1,080 feet wide and 5,750 feet long. The panels will be mined by the retreat longwall method. Panels EI through E8 will be mined from east to west. Panel E9 is planned to be mined from south to north. The trend of panels El through E8 is approximately N80°W. Panel E9 trends roughly N10°E. The overburden depth above the panels El to E4 ranges from roughly 400 to 1,425 feet, whereas, the overburden depth for panels ES to E8 ranges from 500 to 1,250 feet. The overburden above panel 9 ranges in thickness from 500 to 550 feet. All longwall panels aze planned to be sepazated by two or three rows of chain pillazs. The row neazest to the headgate side of the panels is projected to be a rigid pillaz design-on enters 125 feet wide by 200 feet long. The row on the tailgate side of the panel will be of a yield pillaz design---on centers 75 feet wide by 200 feet long. A protective barrier system, 700 feet wide, is currently projected to separate the longwall panels El to E4 and ES to E8. These mine plans and pillaz designs may change as mining experience, geological-geotechnical conditions, and/or mine M operational procedures dictate. 831-032.620 Wright Water Engineers, Inc.