2009-08-19_REVISION - M1987049 (3)

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Applicant's Response: Ground water is the only source of water used at Bromley Lakes. Please see the renewal request for Substitute Water Supply Plan (SWSP) for RMCC-Bromley Lakes Pit (M-1987-049) included with this Adequacy Response. The SWSP was prepared by BBA Water Consultants and is dated July 1, 2009. 25. The installation of the slurry wall may have undesirable effects on the prevailing hydrologic balance of the permit area and the surrounding areas. Please describe how you will minimize the disturbance to the prevailing hydrologic balance of the ground water systems of the affected land and the surrounding area in regards to mounding and shadowing issues both during and after the mining operation and during reclamation? Please include a plan for how mounding and shadowing issues will be monitored and how problems will be identified and mitigated " Applicant's Response: The eventual post reclamation land use of the area identified as Cell No. 3 is developed water storage; however, presently, the Applicant does not intend to install a slurry wall around the perimeter of Cell No. 3. The decision when to install the sTrry wail will be made by the City of Brighton, the eventual owners of the Cell No. 3 water storage reservoir. That said; the perimeter of the slurry wall for Cell No. 3 will be bounded by the following topographic features all of which will serve to mitigate any possible adverse ground water mounding or shadowing affects associated with the slurry wall. First, the North Tower pit is adjacent to the south segment of the slurry wall and up gradient of the direction of flow of the South Platte River. Should sufficient mounding occur in the North Tower Pit water will spill out the northeast corner of the pit into the McCanne Ditch thus serving to mitigate excess mounding if any. Next, the South Platt River is adjacent to the west segment of the slurry wall and will serve to mitigate any mounding along that side of the project. Cell No. 2 boarders the north side slurry wall which is down gradient of the direction of flow of the South Platte and any associated alluvial ground water. Shadowing, if any, will have no adverse affect on Cell No. 2. Finally, the slurry wall on the east side of the proposed reservoir is adjacent to the west side of the McCanne Ditch which will serve to limit ground water mounding, if any, to the invert elevation of the ditch. Indeed, in the long run the east side slurry wall has the potential to enhance the flow of water in the McCanne Ditch. As can be seen, the existing topographic features described above will serve to mitigate any adverse affects of ground water mounding and shadowing associated with 8/19/2009 11