2022-02-22_PERMIT FILE - C1980007 (5)

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West Elk Mine 2.04-12 Rev. 11/04- PR10; 07/18- PR15; 01/22- MR459 2.04.6 Geology Description Introduction The following geologic description of the West Elk Mine permit area is based on publications by C.R. Dunrud (1976), W.R. Junge (1978), Ellis, Gaskill, and Dunrud (1987) C. Richard Dunrud (1989), A. Mayo and W. Koontz (2000), and A. Mayo et al (2004); unpublished reports by V. H. Johnson (1948), Geo-Hydro Consulting (1980), Dames & Moore (1983), Intrasearch, Inc. (1993), J. Corbett (1997), Mayo and Assoc (1998, 2000, 2004), and SRK Consulting (1998); considerable subsurface and surface investigations by ARCO (now MCC) and Ark Land/Arch Resources staff geologists, aerial photo and low altitude aerial and field reconnaissance studies by C.R. Dunrud and J.W. Rold (1994 to 2004), and results from more than several hundred drill holes on or near the property. The locations of these drill holes are shown on Map 8. Holes that were designated "SOM" were drilled in Federal coal and "MG" were drilled in private coal. Four holes were drilled within the permit area by the U.S. Bureau of Mines (USBM) in the 1940's which were given a G designation. Twenty-five (25) holes were completed in 1963 by U.S. Steel Corporation and designated with the "CSM" prefix. Five additional holes were drilled by Grand Mesa Properties in 1981 and designated "MG-***-81." Grand Mesa Properties completed another hole (CP-82-1) in 1982. In 1992 and 1993, MCC completed 13 drill holes through the B- Seam and were given the designation "JMB." Three holes were drilled to the southwest of the mine site in 1994 and were designated "So.W." (These holes should not be confused with the shallow wells completed for the subsidence monitoring program and designated as "SW-1" through "SW- 6"). Holes drilled from 1993 to 1995, to the east of the mine site, toward or on Raven Mesa have been designated "RAV". In 1996, 1997, and 2001, 21 holes were drilled and completed through the B-Seam. They are designated as 96 (or 97 or 01) -*-*. The first entry indicates the year that the hole was drilled. The second entry indicates the section in which the hole was drilled, and the third entry indicates the numbered hole in that section. Later B and E seam exploration used similar nomenclature. Subsurface control; coal distribution, coal thickness, and quality; overburden and interburden thickness and chemical characteristics; structural geology and stratigraphy have been derived using information from all of the drill holes. The locations of drill holes are included on Map 8. All holes were drilled with permission of landowners and permits from appropriate state and federal regulators. Monitoring wells shown on Map 34 and other holes shown on Map 8 were completed or plugged and abandoned (P&A) and reclaimed in accordance with all regulations of the CDRMS and the State Engineer's Office (SEO) applicable at the time. Hole completion data were submitted to the CDRMS. P&A and completion data are also provided in Exhibit 12. Normal practice from 1973 through 1991 entailed rotary drilling to approximately 250 feet above the E-Seam where casing was set and coring continued downward through the B Seam. Since 1992, procedures typically only included spot coring of the E and B Seams and immediately adjacent strata. The typical suite of geophysical logs run on each hole consisted of various combinations of gamma ray, neutron, density, resistivity, self-potential, temperature logs, and caliper. Since 2000, coal quality has been determined from laboratory analyses conducted by Standard Labs of Charleston, WV. Between 1992 and 2000, Commercial Testing and Engineering Laboratories of