2009-01-15_REPORT - C1980007 (8)

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Fall 2008 Subsidence and Geologic Field Observations Box Canyon, Apache Rocks, and South of Divide Mining Areas • The rockfalls and landslides in the Box Canyon, Apache Rocks, and SOD mining areas were examined and photographed to evaluate changes since the last observation (using routinely visited photographic observation points), and to record their condition for future reference (Maps 1-4). One new rockfall/landslide area was noted on the east side of Sylvester Gulch above Longwall Panel 25, which is currently being mined (October 3, 2008). Eleven photographic observation points have been established since 2007. Many of these locations had been used for annual comparative purposes even before their most recent formalized establishment. Two photographic observation points were established in the spring of 2007, seven more points were established in the fall of 2007, and two additional points were established during the spring of 2008 site visit. No new points were established during the fall of 2008 site visit. The two spring 2007 photographic observation points include one that overlooks the Dry Fork drainage, the Minnesota Creek Reservoir, the Deer Creek Ventilation Shaft and Escapeway, and • the lower reaches of the Deer Creek drainage. This location will be used regularly to assess changes that may occur as mining of the E-seam progresses through the area. The second photographic observation point established in the spring of 2007 is on the west side of Sylvester Gulch and provides a good vantage point to view the rockfall and landslide area at the headscarp of Box Canyon. This location is approximately 4,300 feet north of the previous location established for this purpose. Seven additional photographic observation points were established in the fall of 2007 to view rockfalls and landslides in the Box Canyon mining area, the dam and landslide construction in the Minnesota Reservoir area, and the Highway 133 landslides. Two additional photographic observation points were established during the spring 2008 field visit. One location is from near the train loadout facility north of Highway 133 where a full view of the large sandstone rockfall along the south side of North Fork can be readily observed. This site has been visited and photographed previously but was added as a photographic observation point for continued review. The second spring 2008 photographic observation point was 831-032.790 Wright Water Engineers, Inc. Page 15 December 2008