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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />r? <br />Ll <br />again during the fall 2008 field visit (i.e.. after longwall minim had Occurred beneath the area). <br />A photographic comparison of the sandstone outcrop from before and after mining in provided in <br />Section 1.19.2. <br />5.19.1 Location 14 <br />Location 14 is an area of the Box Canyon access road approximately 200 feet Ion,,. \\ here several <br />subsidence-related cracks were observed for the first hI11C dllCltl,, our tall 2008 field visit. This <br />location is above the west end of mined Lon,,wall Panel 18 in an area approximately 500 feet <br />above the B-seam (.Map I ). This location is above the western hOUndary of the Ion,,wall panel <br />and in an area Of MaXII11L1111 tensile strain. <br />Most of the observed cracks were discOntinuous and oriented in a N 10-;0°E direction. Crack <br />lengths were typically 2-3 feet with \vidths ranuing from 1-6 inches (Figure 45). <br />7.4 <br />(R Off.- n t ?.?` i - <br />ifs ' `?`? ti'? rx C t? _ ?,?L? ? :. <br />'• :ti'p'. + . ?'?? ?f ?? Q; . Ja?.d <br />Figure 45. Fall 2008 northward view of several subsidence cracks observed in the Box Canyon <br />access road above the west end of mined Longwall Panel 18 where overburden depth to the B- <br />seam is approximately 500 feet. <br /> <br />Several of the cracks appeared to be more colltinuOUS but partially tilled by settlement or vehicle <br />traffic (Fi,,ure 46). <br />831-032.790 Wright Water Engineers, Inc. Page 59 <br />December 2008