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• GEOLOGSc <br />The geology of the area subject to this request is identical to that <br />in the adjacent permitted area. Geologic continuity has been <br />confirmed by EFCI exploration and development drilling programs. <br />Drill holes SF-87-07, SF-87-08 and SF-87-09 were completed to the <br />east, northwest and southwest respectively, of the area subject to <br />this request (refer to Exhibit 3, Proposed Incidental Boundary Change <br />Area). Descriptions of the geology are discussed in Sections 2.04.5 <br />and 2.04.6 of the approved permit application. As this permit is <br />currently in a state of revision, excerpts and additional information <br />are additionally incorporated into this Technical Revision application <br />as follows. <br />Southfield is minrr~g coal fran two seam canplexes in the Cretaceous <br />Vermejo Formation in the Canon City Coal Field of Colorado. Under <br />previous ownership, mains were initially driven into the Red Arrow <br />Seam. Later these mains were ramped into the stratigraphically <br />overlying Jack O'Lantern cortQlex. <br />The Red Array Seam ocrtiplex is a moderate to high sulfur (+ 1.2 lbs SOy <br />/moSf0) coal consisting of 3 reoogruzable coal units. Atypical face <br />description of the seam in the 2 North area is as follows: <br />Upper Unit 1.0' coal <br />• "Upper" Parting <br />Middle Unit 0.2' <br />2.2' bone / carbonaceous shale <br />coal <br />"Lacer" Parting 0.5' bone <br />Lower Unit 2.0' coal <br />Each coal unit has unique sulfur croncentrations. In 2 North the <br />highest sulfur concentrations are generally located in the roof and <br />the adjacent Opper Onit. During time periods when law sulfur coal <br />production is mandatory, a near ccaq~liance coal can be produced from <br />the Red Arrow by leaving 0.5' to 1.0' of croal in the roof. <br />Tb the west and northwest of 2 North a third parting increases the <br />sulfur and ash content of Red Arrow's middle unit. This "middle" <br />split marks the end of ewnomic Red Arrow development due to the <br />decrease in coal content (less than 50~ by weight) and the increase of <br />rock content (see Exhibit 3). This limiting split has been the <br />subject of exploratory activity since 1987 when a series of carefully <br />placed Dore holes discounted the existence of a western extension of <br />the Red Arrow Seam currently being developed in 2 North. <br />Similar ,splitting conditions form an econanic baudary on the east <br />side 'of Southfield. .; These wnditions were first intercepted in the <br />eastern roost development of Southfields 1 North r",t,",a;.,. The <br />_.,;~Y-=::.:. boundaries of this eastern split are reasonably delineated from face <br />descriptions and Dore hole data. =.;°~ - ~ . _ ~ , -- -:^'::1~'~ <br />• The east split and west split were thought to wntinue across the <br />north bauidary of 2 North and limit its development in length to 4,500 <br />feet, the boundary for TR-OS !approved May 19, 1989). Upon reaching <br />the rorthern most extension of TR-05 it was found that the west split <br />