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In the fall of 1985, Mountain Coal Company submitted a permit revision application <br />requesting approval of a permanent lower waste pile to be located adjoining the mouth <br />of Sylvester Gulch. This application originally requested approval to permanently <br />dispose of 1.77 million tons of coal processing waste within the proposed structure. <br />The original design phased the refuse pile into five specific design layouts (Phases I <br />through V), including recompaction and reconfiguration of temporarily stored waste <br />material. The pile was constructed according to this original phased design until the <br />Phase IV configuration. A revision application was submitted in November 1992, <br />which eliminated Phase V and reduced the pile to 1.2 million tons. The proposed <br />storage volume represents a 15.7 year life. The proposal included the combination of <br />a 28,500 cubic yard topsoil pile during Phases I through III and a maximum of 45,000 <br />cubic yards of non-toxic soil cover (subsoil) stockpile. Topsoil removed for Phase IV <br />will be stored on the 50-foot bench constructed in Phase III. In addition, an access <br />road was constructed in Phase Three and a portion of the Sylvester Gulch access road <br />to the main fan portal was relocated. Underdrains have been constructed beneath the <br />pile. Piezometric groundwater monitoring will be conducted. Slopes of the pile will <br />be maintained at 2.SH:1V. <br />The permit revision application included a thorough slope stability analysis performed <br />in accordance with the prudent state-of-the-art slope analysis for the original design in <br />1985, and for the redesigned pile in 1992. Material strength values were derived from <br />on-site sample testing and nearby previously reported test results. Piezometer <br />observations, falling head parameter tests and analytical projections were completed in <br />order to predict appropriate phreatic surfaces within the proposed waste structure. <br />Data for the 1992 analysis utilized data collected for the 1985 analysis. <br />The applicant has committed to the installation and quarterly monitoring of three sets <br />of survey monuments to monitor slope stability of the waste structure. One row of <br />monuments has been installed parallel to the state highway adjoining the toe of the <br />waste pile on ]00-foot intervals. Two additional rows of monuments have been <br />installed perpendicular to the highway on the facial slope of the pile at 50-foot interval <br />spacing. The operator has also committed to quarterly reporting of visual inspections <br />of the topsoil, non-toxic soil cover stockpiles, and refuse pile. <br />For the Lower Permanent Waste Pile, drainage will be controlled by a series of <br />drainage ditches and a sedimentation pond. Since the pile will be constructed in <br />phases, the drainage system will also be built in phases. All disturbed area drainage <br />from the waste pile will be routed to the sedimentation basin at the northwest corner of <br />the lower waste pile (MB-2R). <br />The design incorporates several permanent drainage features into the plan. A hundred <br />year diversion ditch has been constructed around the perimeter of the pile to <br />permanently collect any runoff from the site and safely route it to the natural drainage <br />system. For a discussion of the hydrologic effects of the waste pile on both surface <br />and groundwater, see the hydrology section in the Probable Hydrologic Consequences <br />section of this findings document. <br />48 <br />