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De;remL~er 9 , 20Q3 <br />Pace 3-3 <br />MCC has been mining and subsiding areas to the west and southwest of the West Flatiron lease tract <br />since 1981. The land surface has lowered in these areas from between two to ten feet. These changes in <br />elevation are not noticeable to the casual observer. Surface tension cracks on sandstone outcrops have <br />been noted in the western portion of Section 28, T13S, R90W (a place known as Apache Rocks), and in <br />the northern portion of section 27, T13S, R90W. These are surface tension cracks that range from one to <br />three inches wide and extend up to 50 feet on the surface. These cracks are believed to range from 20 to <br />30 feet in depth. These cracks are not expected to close completely, but will be visible to observers in <br />those specific locations for years to come. <br />Alternative 2 - No Action <br />If the no action alternative is selected, no mining activities would occur in the coal resources of the West <br />Flatiron LBA tract. Thus, there would be no topographic changes as a result of mining the coal resources <br />in the LBA tract, but the proximity of mining adjacent to the LBA tract would cause subsidence effects <br />given the angle of draw expected from longwall mining. Natural landslides and rock falls would continue in <br />the area, given existing and natural geologic instability in the region. Subsidence would occur on the <br />leased lands to the west of the tract. <br />3.2.3 Potential Lease Stipulations <br />Subsidence monitoring is a requirement of a mine permit issued by the Colorado DMG. if surface cracks <br />occur that affect other uses (roads, trails, etc.), the surface management agencies have authority to <br />require timely on-site mitigation. The effectiveness of these measures would be uncertain and would <br />depend on the individual circumstances of the mitigation. <br />1) Use of the LBA tract would also be subject to the following special operating constraints as part of <br />the mine permit: <br />a) The operator/lessee shall perform a study to secure adequate baseline data to quantify the <br />existing surface resources on and adjacent to the lease area. Existing data may be used if <br />such data is adequate for the intended purposes. The study shall be adequate to locate, <br />quantify, and demonstrate the inter-relationship of the topography, geology, surface <br />hydrology, vegetation and wildlife. Baseline data will be established so that future programs <br />of observation can be incorporated at regular intervals for comparison. This measure is highly <br />effective in understanding any changes or impacts to the resources of the LBA tract. <br />b) The operator/lessee shall establish a monitoring system to locate, measure and quantify the =- <br />progressive and final effects of underground mining activities on the topographic surface, <br />underground and surface hydrology, and vegetation. The monitoring system shall utilize <br />techniques which will provide a continuing record of change over time and an analytical <br />method for location and measurement of a number of points over the lease area. The <br />monitoring shall incorporate and be an extension of the baseline data. This measure is highly <br />effective in understanding any changes or impacts to the resources of the LBA tract. <br />2) No surface occupancy or use would be allowed on the LBA tract where slopes are greater than <br />60 percent. This measure is highly effective in preventing impacts to land surface. <br />F_nvirnni;~ental Assessment <br />'!vast Flatiron LBA Tiact <br />~:,r~r,r;ison County, Colu~ado <br />