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831 - 032.793 <br />May 2012 <br />Fall 2011 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />location is used to observe some of the historic landslides that have plagued the Colorado <br />Department of Transportation relative to impacts on Colorado Highway 133 (Hwy 133). <br />Observations from this location show the relatively recent slide that occurred adjacent to the <br />Refuse Pile Expansion area, located immediately south of Hwy 133 and east of the main entrance <br />to the West Elk Mine. This is an area identified with a very high rockfall /landslide potential <br />according to Map 3 of this, and previous, reports. This slide occurred well after B -seam longwall <br />mining occurred in this vicinity. <br />In the SOD mining area, subsidence related cracks had been observed and reported during the <br />spring 2011 field visit in the general vicinity of the confluence of Horse Gulch and Dry Fork. In <br />particular, on the recently undermined drill pads for methane drainage wells (MDWs) E2 -09, <br />along the road between E2 -13 and E2 -09, and along U.S. Forest Service (USFS) Road 711 (Dry <br />Fork Road) downstream of the confluence. At the time of our fall 2011 field traverses, these <br />previously observed subsidence cracks had healed and sealed substantially. In some instances, <br />the cracks were nearly unrecognizable with only minor evidence remaining in cut banks. Cracks <br />were still visible on the E2 -09 MDW pad although considerable healing of this area had also <br />occurred such that cracking was no longer continuous over any great distance. In addition, <br />baseline observations were made of several new MDW pads above unmined portions of E -seam <br />Longwall Panels E3 in the SOD mining area. Several of these pads were observed to contain <br />differential settlement cracks in the largest fill areas of the pad (likely due to ongoing settlement <br />of the fill material). Details and examples of this phenomenon can be found in numerous <br />previous reports. One subsidence - related crack was noted on the road southeast of the E3 -72 <br />MDW pad. Additional details regarding the SOD mining area observations can be found in <br />Section 3.0 of this report. <br />Wright Water Engineers, Inc. Page 4 <br />