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West Elk Mine • South of Divide Mining Area -The longwall mining method will be utilized in the South of Divide mining area. The planned panel design is similar to the current West Elk Mine longwall panels where subsidence measurements were used to obtain the baseline data on which this discussion is based. A range of 8 to 14 feet of coal will be extracted from the E Seam depending on seam structure, coal quality, and other operating constraints. It is anticipated that extraction will be limited to 12 feet only on the easternmost edge of the panels. The extraction thicknesses are projected based on exploration hole data; actual thicknesses may vary depending on mining conditions encountered. Longwall Panels El through E8 are all projected to be 1,080 feet wide and range from about 9,000 to 11,000 feet long. 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 El through E8 will be mined from east to west. Panel E9 is planned to be mined from south to north. The panel layouts for the South of Divide mining areas are shown on Map 51. 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 E9 ranges in thickness from 500 to 550 feet. All longwall panels are planned to be separated by either two or three rows of chain pillars. The row nearest to the headgate side of the panels is projected to be a rigid pillar design on • centers 125 feet wide by 200 feet long. The row on the tailgate side of the panel will be of a yield pillar design on centers 75 feet wide by 200 feet long. A protective barrier system, approximately 700 feet wide, is currently projected to separate longwall Panels El-E4 and ES-E8. Mine plans and pillar designs may change as mining experience, geological- geotechnical conditions, and/or mine operational procedures dictate. Geologic Factors Influencing Subsidence - 2.05.6 (6)(e)(i)(B) Subsidence is influenced by the local geology in the following ways: Geologic Structure Attitude of the bedrock, faulting, and jointing may control mine layout and mining method. In steeply dipping, faulted coal beds, for example, a certain mine layout and method, such as room- and-pillar or limited panel-pillaz may be required. Joints often control the way in which the roof rocks break, cave, and fracture, both underground and at the surface during mining and subsidence. In relatively flat-lying, unfaulted coal seams like the South of Divide and current mining azea, there is latitude to develop the most efficient layout and method to recover a maximum amount of the coal resource with a minimum of impact. Strength and behavioral properties of the rocks These properties may control the amount and rate of subsidence. Strong, brittle sandstones and siltstones tend to break and cave in lazge blocks on the mine floor. The bulking factor is greater for ~. 2.05-/06 RevisedN°vember 2004 PRIG