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Fall 2007 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br /> <br />• <br />5.3 Traverse C-C' <br />Traverse C-C' begins at the fork in drill roads above the south gate road entries of longwall <br />pane124 and ends at the drill pad containing Methane Drainage Wells (MDWs) 19-01, 19-02, <br />and 19-03 above the northeast corner of the mined longwall panel 19. <br />The traverse winds northward along a drill road above mined longwall panels 24 to 22, partially- <br />mined panel 21, recently mined panel 20, and mined panel 19. Overburden depth to the B-seam <br />varies from 2,150 to 2,250 feet along this traverse. <br />Soil and colluvium as much as 10 feet thick, derived from clays and silts of the Wasatch <br />Formation and the underlying Ohio Creek Member of the Mesaverde Formation, were <br />encountered on the road. Several cracks were observed in 2006 and again visited in the fall of <br />2007 above the northeastern edge of mined longwall panel 19, on the northern edge of the drill <br />pad for MDWs 19-01, 19-02, and 19-03 (location 5). New, actively widening and lengthening <br />cracks were noted both in the drill road and in the MDWs 21-32, 21-36, and 21-38 drill pad area <br />(on the west side of the road) over the northeast corner of mined longwall panel 21 (location 3). <br />5.3.1 Location 3 (Location 5 of the Spring 2007 Field Visit) <br />This is the site of extensive new cracks, which have occurred since the spring 2007 field visit. <br />These cracks, which are located both in the main West Flatiron drill road and in the drill pad for <br />MDWs 21-32, 21-36, and 21-38, occur above the mined part of longwall panel 21 (currently <br />being mined). The maximum cumulative extension of the crack sequence was estimated to be 2 <br />to 3 feet at the time of the site visit (September 26th). MCC mine personnel reported that the <br />cumulative crack extension was no more than one foot when the area was visited one week prior <br />to this recent visit. These cracks are located at one of the two narrowest portions of the ridge top <br />of West Flatiron where the overburden depth to the B-seam is about 2,150 feet. The cracks now <br />transect the entire ridge. Initial cracks observed in spring 2007 at this location were most likely <br />caused by lateral spreading due to gravitational forces. <br />831-032.780 <br />November 2007 <br />Wright Water Engineers, Inc. Page 19 <br />