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consistent with the need for verification of the subsidence <br /> prediction. <br /> MCC has extended the subsidence monitoring network to include Jumbo <br /> Mountain. The location of the monuments is shown on an Addendum to <br /> Exhibit 60. In addition, MCC will establish and survey an aerial <br /> photo control point grid, complete aerial photography of the mine <br /> plan area, and then use photogrammietric methods to measure <br /> subsidence- MCC will verify the effectiveness of this methods by <br /> continuing the conventional survey of the existing grid and of the <br /> decreed water rights on Jumbo Mountain to be under mined. If <br /> aerial photogrammetry is successful, MCC will then submit a <br /> revision to eliminate surveying by traditional methods. <br /> In addition to providing subsidence survey data, the aerial photos <br /> from the fall photogrammetric survey will be utilized to map the <br /> numerous, small landslide bodies on the north face of Jumbo <br /> Mountain. This mapping will provide a broader, more extensive view <br /> from which to associate or assess landslide activity due to mining. <br /> An evaluation of the F seam subsidence monitoring program is <br /> provided in Exhibit 60. The evaluation includes an analysis of the <br /> survey data obtained from the F seam monitoring network to date, <br /> correlation with industry subsidence protection models, and summary <br /> of subsidence parameters observed for the F seam. Predictions of <br /> subsidence from proposed mining in the B seam are included and are <br /> based on data and evaluations of the F seam subsidence and current <br /> industry data. <br /> XVI . Concurrent Surface and Underground Mining <br /> 1. This section does not apply to the West Elk Mine. <br /> XVII. Operations on Alluvial Valley Floors <br /> The applicant has performed a detailed reconnaissance investigation for <br /> alluvial valley floors. During the investigation, the applicant <br /> identified several areas within or adjacent to the mine plan area which <br /> may meet the geomorphic criteria of alluvial valley floors. Alluvial <br /> deposits were identified along Minnesota Creek, the Dry Fork of <br /> Minnesota Creek, Sylvester Gulch, and the North Fork of the Gunnison <br /> River. <br /> Two of these areas, .Minnesota Creek and the Dry Fork of Minnesota <br /> Creek, although geographically adjacent to the permit area, are not <br /> hydrologically adjacent to the activities approved in the permit. Both <br /> a surface water divide and a ground water divide separate these areas <br /> from mining activities. However, since part of the Minnesota Creek <br /> drainage lies within the 40-year life-of-mine lease boundary and may be <br /> affected by future mining, it will be considered in this determination. <br /> An area identified in the permit application which may meet the <br /> geomorphic criteria of alluvial valley floors is located along <br /> Sylvester Gulch. The lower refuse pile is being constructed west of <br /> the mouth of Sylvester Gulch, in a portion of the area identified. The <br /> applicant estimated the area to be approximately 20 acres in size. <br /> However, upon examination of the Division's aerial photographs, the <br /> area of possible fill may be considerably smaller. Also, it has been <br /> confirmed by geologic mapping by the Colorado Geological Survey (lunge, <br /> 1978) that the deposits are not of alluvial origin, rather <br /> colluvial-wedge deposits formed by gravity-dominated processes. On the <br /> basis of this information, this area is found not to meet the <br /> geomorphic criteria for an alluvial valley floor. <br /> Another possible location for an alluvial deposit is found within the <br /> west branch of Sylvester Gulch. However, alluvial origin of the <br /> 46 <br />