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SPRING 2007 Subsidence and Geologic Field Observations <br />Box Canyon, and South of Divide Mining Areas <br />In addition, monitoring stations are presently being established on Monument Dam and at <br />strategic locations around Minnesota Reservoir. Specific details of these locations will be <br />provided in the Fa112007 Subsidence Report. <br />4.0 OVERVIEW OF SPRING 2007 FIELD STUDIES <br />This subsidence report is the first of two reports that will be generated during the 2007 calendar <br />year. As of this report, the subsidence monitoring and reporting will be conducted biannually. <br />This report describes the field observations made on April 19 and 20, 2007, which represent the <br />first time that many of the subsidence monitoring areas have been observed during the <br />springtime. As a result, the areas visited were much wetter with observed springs and seeps that <br />did not exist during previous observations in July, August, and September of previous years. <br />These observations provide additional subsidence considerations as a function of season and <br />hydrologic conditions in the spring and fall. <br />Subsidence observations were conducted in the Box Canyon, Apache Rocks, and South of <br />Divide mining areas. A 4-wheel drive vehicle and foot travel were used to efficiently conduct <br />the field observations. <br />Prior field observations and experience in the West Elk Mine area during field studies over the <br />last 11.5 yearst indicate that subsidence features (cracks and bulges) are most visible on roads <br />and trails, where the ground is more compact and free of brush. These areas were therefore <br />selected, in addition to undermined areas free of brush, in order to most efficiently obtain <br />maximum subsidence information. <br />The rockfalls and landslides in the Box Canyon, Apache Rocks and South of Divide mining <br />areas were examined and photographed to evaluate changes since the last observation, and to <br />record their condition for future reference. During the summer of 2006, a geological engineering <br />~ Annual subsidence and geologic hazard reports are kept at Mountain Coal Company, LLC and at the Colorado <br />Division of Mining, Reclamation and Safety, as well as exhibits [o [he pemilt document (Exhibits 6Q 60A, 606, <br />and 60D). <br />831-032.780 Wright Water Engineers, Inc. Page 9 <br />July 2007 <br />