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West Elk Mine cracks occur above the narrow, rigid boundary pillaz. The cracks may be the result of any ~ or a combination of all of the above circumstances. According to C. R. Dunrud, these cracks aze larger than any he saw in his previous extensive subsidence research in the entire North Fork Valley. 3. In the fall of 1994, a series of cracks appeared along an unimproved road south of Lone Pine Gulch near the center of the NWl/4 of Section 20: The cracks occurred near the center of the north half of the 5NW longwall panel and above the western boundary of previous room-and-pillaz mining of the F-Seam. Careful study by Messrs. Dunrud and Rold indicated that the most likely, but not conclusive, explanation of the cracks was that subsidence had reinitiated slight movement in old landslide deposits. 4. A limited set of cracks occurred above the barrier pillar on the east boundary of 1NW longwall panel, along the east line of Section 20. Again, this azea'was also affected by room-and-pillaz mining in the F-Seam. 5. While mining was occurring in SNW longwall panel, MCC received a complaint from the land owner regarding cracks on his property. As a result of the complaint, CDMG conducted an inspection of the surface cracks on the owner's property and wrote an inspection report summarizing their observations (CDMG 1996). Since Wright Water Engineers was denied access to the site by the land owner, and therefore limited to low- elevation aerial reconnaissance, the discussion of the mechanism behind the formation of these cracks relies mostly on the CDMG inspection report: These cracks were observed in the vicinity of a relatively large, historic, episodically active landslide (Dames and Moore 1993). Extensive recent landsliding was observed in the SWl/4 of Section 24 in the spring of 1996. The landslide activity created numerous cracks and "graben-like extensional troughs up to ten feet wide and five feet deep." These ' cracks were parallel to the fall line, which is typical of the translation of the sliding debris as shown in Figure 19. According to Dr. Pendleton of CDMG, the observed features are typical of large landslide masses in the Williams Fork Formation (geological equivalent of the Mesaverde Formation) and they occur prolifically throughout the North Fork Valley on slopes of varying gradient and aspect. Based on his experience in the Forth Fork Valley, Dr. Pendleton concluded that subsidence does not appeaz to be a significant determinant in the reactivation or initiation of landslide activity. CDMG concluded that "there is no evidence with which to definitively verify or discount a connection between subsidence of the MCC mine workings and this active landslide." Eight crack locations were visited during the CDMG inspection. While most of the surface cracks were attributable to rejuvenated landslide movement, three minor cracks were reported to be the result of mining subsidence (Nos. 2, 3, and 8 on Figure 19A). These cracks were three to four inches wide and less than one foot deep. Field observations by MCC personnel indicated that these cracks were already healing, shortly after,mining had occurred. Two of these cracks (Nos. 3 and 8) are typical of the dynamic • subsidence process. As mining occurs, the overburden above the mined portion subsides and differential movement results between the mined and unmined areas. Surface 2.05.103 Revised Jun. 1995 PR06; 1/96 RN03; Revised May 1999 TR89; Revised Jan. 1998 PR08;March 2005 PRII O`j .l~ M