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West Elk Mine <br />2.04.6 Geology Description <br />Introduction <br />The following geologic description of the West Ells Mine permit azea is based on publications by <br />C.R. Dunrud (1976), W.R. Junge (1978), Ellis, Gaskill, and Dunrud (1987) C. Richard Dunrud <br />(1989), A. Mayo and W. Koontz (2000), and A. Mayo et al (2004); unpublished reports by V. H. <br />Johnson (1948), Geo-Hydro Consulting (1980}, Dames & Moore (1983}, Intraseazch, Ina (1993), J. <br />Corbett (1997), Mayo and Assoc (1998, 2000, 2004), and SRK Consulting (1998); considerable <br />subsurface and surface investigations by ARCO (now MCC) and Arch Coal staff geologists, <br />aerial photo and low altitude aerial and field reconnaissance studies by C.R. Dunrud and J.W. Rold <br />(1994 to 2004), and results from more than 238 drill holes on or near the property. The location of <br />these drill holes is shown on Map 8. <br />Holes aze designated "SOM" for those drilled over Federal coal and "MG" for those drilled over <br />private coal. Four holes were drilled on the lease azea by the U.S. Bureau of Mines (USBM) in the <br />1940's which were given a G designation. Twenty-five (25) holes were completed in 1963 by the <br />U.S. Steel Corporation and designated with the "CSM" prefix. Five additional holes were drilled by <br />Grand Mesa Properties in 1981 and designated "MG-***-81." Grand Mesa Properties completed <br />another hole (CP-82-1) in 1982. In 1992 and 1993, MCC completed 13 drill holes through the B- <br />Seam and were given the designation "JMB." Three holes were drilled to the southwest of the mine <br />site in 1994 and were designated "So.W." (These holes should not be confused with the shallow <br />wells completed for the subsidence monitoring program and designated as "SW-1" through "SW- <br />6"). Holes drilled from 1993 to 1995, to the east of the mine site, toward or on Raven Mesa have <br />been designated "RAV". In 1996, 1997, and 2001, 21 holes were drilled and completed through the <br />B-Seam. They aze designated as 96 (or 97 or Ol) -*-*. The first entry indicates the yeaz that the <br />hole was drilled. The second entry indicates the section in which the hole was drilled, and the third <br />entry indicates the numbered hole in that section. <br />Subsurface control; coal distribufion, coal thiclmess, and quality; overburden and interburden <br />thiclrness and chemical chazacteristics; structural geology and stratigraphy have been derived using <br />information from all of the drill holes. More than 45 holes have been drilled on or within a quarter <br />mile of the South of Divide permit revision azea. The location of those drill holes aze included on <br />Map 8. All holes were drilled with permission of landowners and permits from appropriate state <br />and federal regulators. Monitoring wells shown on Map 34 and other holes shown on Map 8 were <br />completed or abandoned and reclaimed in accordance with all regulations of the CDMG and the <br />State Engineer's Office (SEO) applicable at the time. Well completion data and test results have <br />been submitted to the CDMG with Annual Hydrology Reports. Complefion data are also provided <br />in Exhibit 12. <br />Normal practice from 1973 through 1991 entailed rotary drilling to approximately 250 feet above <br />the E-Seam where casing was set and coring continued downwazd through the B Seam. Since 1992, <br />procedures typically only included spot coring of the E and B Seams and immediately adjacent <br />strata. The typical suite of geophysical logs run on each hole consisted of various combinations of <br />.~ gamma ray, neutron, density, resistivity, self-potential, temperature logs, and caliper. Since 2000, <br />coal quality has been detemuned from laboratory analysis conducted by Standard Labs of <br />2.04-12 Revimd November 1004 PRIG <br />