2011-09-23_REPORT - C1980007 (7)

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• • 5.4 Traverse K -K' 831 - 032.793 September 2011 Spring 2011 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas • 2011 field activities. Mining had already occurred beneath each of these MDW pads. No changes were observed along this traverse or at the various MDW drill pads. This traverse follows Dry Fork Road from Monument Dam (Minnesota Reservoir) eastward to just beyond the point where the road crosses Deep Creek (see Maps 2 and 4). Portions of this traverse are above mined E -seam Longwall Panel El and E2 as well as unmined portion of E- seam Longwall Panels E3 through E5. The extreme western end of this traverse is in the immediate vicinity of Minnesota Reservoir and outside the proposed E -seam mining influences of Longwall Panels El through E9. Thick soil and colluvium derived primarily from the Wasatch Formation is observed along this traverse. Overburden depth to the E -seam along this traverse ranges from 400 to 1,200 feet. The estimated thickness of the surficial material ranges from 75 to 250 feet. Photographic Observation Point 12 is located along this traverse (see Section 5.4.1). This photographic location was established to view an area of free - standing sandstone columns (or stacks) above the eastern end of E -seam Longwall Panel El to observe evidence of subsidence. A comparison between photographs taken in fall 2009 and spring 2010 revealed that one of the rock columns had collapsed shortly after mining beneath the area. During the spring 2011 field visit, Photographic Observation Point 12 was also the point of observed subsidence cracks in the roadway resulting from the recent mining of the western end of E -seam Longwall Panel E2. This location (Location 3) is discussed further in Section 5.4.2. In addition, four small traverses that originate from Traverse K -K' were visited as part of the spring 2011 observations. Traverses K2 -K2', K3 -K3', and K4 -K4' are above mined portions of E -seam Longwall Panel E2 (Map 2). Traverse K1 -K1' is above unmined portions of E -Seam Longwall Panels E3 and E4 (Map 2). Each of these traverses is discussed independently in their own section of this report (i.e., Sections 5.5 through 5.9). Traverse K5 -K5' was not visited during the spring 2011 field visit because no new activities have occurred in this area and mining beneath this traverse will not occur for at least a year. This traverse travels northward from Wright Water Engineers, Inc. Page 20