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2. Section 2.05 and Map 53 of the permit application provide information on the <br />perennial portion of Sylvester Gulch. The information was submitted in Technical <br />Revision 25. The information includes: depth of mining, height of mining, lithologic <br />description of overburden, and a map of the workings. Based on this detailed <br />subsurface information, the Division previously found that MCC's proposed <br />undermining of the portion of the perennial portion of Sylvester Gulch will not cause <br />material damage to the main channel or east fork of Sylvester Gulch. (4.20.4). <br />Flow in Deep Creek in the Dry Fork lease area is perennial. Two of the operator's B <br />seam panels previously undermined the segment of Deep Creek that is downstream <br />from the Dry Fork lease area. Detailed underground information provided in the PR <br />-12 submittal and in the existing permit application (workings maps, depth of <br />mining, height of mining, and the lithologic description of overburden) indicates <br />subsidence may cause localized temporary pooling and temporary accelerated <br />erosion in the channel. Exhibit 55 B contains a prediction that undermining of Deep <br />Creek in the Dry Fork lease area by panels 3 and 4 will tilt the 7.3% pre-mining <br />slope of the stream by 1.9%, an amount too small to significantly change the <br />hydraulic characteristics of the stream. Exhibit 55 B (p. 35) predicts mining effects <br />on Deep Creek in the Dry Fork lease area will be the same as the previously <br />undermined section of Deep Creek which had no detectable impacts, indicating the <br />depth to mining in the Dry Fork lease area (which is similar to depths downstream) <br />is sufficient to prevent subsidence fractures from capturing significant volumes of <br />stream flows. Based on this information, mining in the Dry Fork lease area does not <br />appear to have the potential to cause material damage to Deep Creek. <br />3. Until 1999, subsidence monitoring at the West Elk Mine was accomplished using <br />conventional survey methods of a monument grid. The monitoring of MCC's <br />subsidence grid established the amount of subsidence that occurs over a longwall <br />panel, when and where it occurs and when it is complete. MCC was approved to <br />replace the monument survey with a visual inspection of the ground over areas that <br />have been undermined to document any disturbance. A survey is done prior to <br />mining and to areas where effects of subsidence were previously noted in order to <br />monitor the healing of cracks. Given the heavy snow cover and inaccessibility of <br />most of the affected area, MCC conducts the surveys during the summer of each year <br />and reports the results by the end of September. Any mechanical response detected <br />during these surveys that is not consistent with previous observations will be reported <br />to the Division within ten working days of the survey. <br />Due to the extremely steep topography and dense vegetative cover of the West <br />Flatiron area, MCC has proposed a subsidence monitoring program, in accordance <br />with Rule 2.05.6(6)(c), designed to concentrate on the landslide areas nearest <br />Highway 133. MCC will drive steel rods vertically into the old landslide body and <br />monitor these rods to assess any movement. <br />Section 2.05.6(6) of the permit application specifies proposed subsidence monitoring <br />locations, frequencies, and methods for the South of Divide area and the perennial <br />portion of Sylvester Gulch. Methods include surveying monuments, aerial <br />51