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West Elk Mine • In the South of Divide mining area the overburden depth to the E Seam ranges from approximately 350 feet above the east eastern edge of longwall panel E2, to 1,300 feet above the western limit of longwall panels E6 and E7 (350 to 400 feet is the minimum overburden depth in the northwestern part of the mine area). However, based on observations made by Mr. Dunrud above the Somerset Mine in the Bear Creek azea, subsidence cracks aze not expected to occur in the Dry Fork alluvium where the overburden depth ranges from 350 to 800 feet. No cracks, and no change in stream flow, were observed in the Bear Creek alluvium (estimated to be 10 to 15 feet thick) when coal was extracted by room-and-pillaz methods at depths ranging from 220 to 300 feet beneath Beaz Creek (Bureau of Land Management, et al., 2002). The probable reason for the lack of cracking in alluvium is that the fine sand- to clay-sized material and overlying soil yields without cracking or bulging as it deforms as a discrete unit, or as discrete units, in the subsidence process. This same reasoning also applies to the coIluvium in the area. Although subsidence cracks were locally observed in colluvium less than one foot to a few feet thick, no cracks were observed in colluvium more than about ten feet thick. No cracks have been observed in alluvium above mined longwall panels in the Apache Rocks and Box Canyon mining areas. Surface-water monitoring in the Dry Fork and Lick Creek drainages will continue in order to compare the historic information derived from annual subsidence observations in the West Elk Mine azea with field observations in selected azeas of the South of Divide mining area. Subsidence depressions, slope changes, and strain are projected to occur in above longwall • panels E2 through E8 in Dry Fork and its tributaries and in Lick Creek when the panels are mined. The maximum subsidence amount, slope change (tilt), and strain aze projected to occur above solid coal barriers and mined longwall panel boundaries, such as above the west ends of longwall panels E2 and E3 in 350 to 400 feet of overburden. Depressions, ranging in depth from 8.4 to 11.2 feet, aze projected in this area. Maximum changes in slope (tilt), ranging from 1.3 to 6.4 percent, are also projected for this area. The maximum horizontal tensile and compressive strain is projected to range from 0.7 to 4.2 percent. Subsidence depressions and slope changes will be less above the gate road pillazs than above solid coal bamers, because they are projected to yield during mining by as much as 4 feet (Table 2 of Exhibit 60B). No subsidence depressions or changes in stream gradient were observed in Deep Creek, located about 1,050 feet above mined longwall panel 17 during the annual traverse in July 2004. There was no observable change in stream gradient or in stream flow. The depression and change in gradient were appazently sufficiently gradual, so as to not be perceived by the author during the traverse along the trail by the stream. • 2.05-737 Revised November 2004 PRIO