Laserfiche WebLink
Fall 2014 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />3.4 Traverse D -D' <br />This is the first of four named traverses that originate from Traverse C -C'. This traverse starts at <br />the USFS gate immediately east of Deep Creek along Dry Fork Road (C' of Traverse C -C') and <br />proceeds northward to the eastern end of E -seam Longwall Panel E3 (see Maps 1 and 2). This <br />traverse leads to five MDWs on two separate pads (E3 -68, E3 -72, E3 -75, E3 -76, and E3 -78). No <br />subsidence features were noted along this traverse during the fall 2014 field visit. <br />3.5 Traverse E -E' <br />This traverse originates along the north side of Dry Fork Road and continues northward across the <br />eastern mined portion of E -seam Longwall Panel E3, E4 and E5. This traverse terminates at an <br />MDW pad containing E3 -64/65 above mined E -seam Longwall Panel E3. <br />This traverse contains several side tracks to other MDW pads including E3 -59/63 (above mined <br />E -seam Longwall Panel E3) E4- 1/2/3, E44, and E4 -5/6 (above mined E -seam Longwall Panel E4) <br />and E5 -5 and E5 -6/7 (above mined E -seam Longwall Panel E -5). Fall 2014 field observation <br />found no subsidence - related features on any of these pads except MDW E4 -1/2/3 (Location 1). <br />3.5.1 Location 1 <br />Prior to longwall mining beneath the MDW E4 -1/2/3 pad in January 2013, several small cracks <br />were observed along the crest of the outside fill slope (i.e., the area of the pad with the greatest <br />vertical fill depth). This observation, prior to mining beneath this location, indicates differential <br />settlement associated with the large fill at the outside edge of the MDW pad. Similar cracks were <br />observed on the outside portion of the pad during the spring 2013 field visit. These cracks were <br />described as differential settlement cracks that were exacerbated by the longwall mining activity <br />that had occurred shortly before that field visit. Additional evidence to support these features as a <br />result of differential settlement was that the cracks could not be traced off the pad in either <br />direction. <br />Some evidence of these cracks (with an approximate N10 °W orientation) was again observed <br />during the fall 2014 field visit with maximum dimensions slightly wider (3 inches) but shallower <br />(8 inches) than observed during the spring 2014 field visit. Figure 3 shows the cracks as observed <br />831 - 032.796 Wright Water Engineers, Inc. Page 9 <br />March 2015 <br />