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Backfilled Areas <br />In Phase 1 of the reclamation, mining Cell 1 will be backfilled to create intermixed wetland and <br />upland pastureland as mining progresses. The created wetland areas will provide mitigation for <br />the adjacent Wattenberg Lakes site (Permit Number M2001008) and a source for wetland <br />banking. Created slopes will generally be shallow and flowing, but will be at a minimum <br />3H:1 V. The fmal elevation of the backfilled area will be determined by estimates of the local <br />groundwater elevation. In general, the mine cell will be backfilled to a height approximately <br />2 feet above the average groundwater elevation. Although the backfilled ground elevation may <br />be below the high groundwater elevation in the created wetland areas, backfilled elevations will <br />still be high enough to prevent permanently exposed groundwater. It is anticipated that the <br />majority of the backfill material for Cell 1 will be composed of fines from the on-site processing <br />facility, but overburden material from the site and the adjacent Wattenberg Lakes site may also <br />be used. <br />For reclamation during Phase 5, overburden material will be available to backfill mining Cell 5 <br />for industrial use, including the existing concrete batch plant. Additional overburden material <br />will also be available from the adjacent Wattenberg Lakes site. The backfill material for this <br />area will be placed and compacted to provide adequate stability for the anticipated future use. <br />The fmal elevation of the backfilled area will be at least 2 feet above the estimated maximum <br />local groundwater elevation. In addition, the final backfill elevation in this area will be as near <br />to the existing and surrounding ground elevation as possible (depending on the availability of <br />backfill material). Grading will create relatively flat surfaces appropriate for industrial uses. <br />Any slopes remaining will be reclaimed to a minimum 3H:1 V grade. As fmal slopes aze graded, <br />topsoil will be placed to provide a growing medium for the vegetation cover used to stabilize the <br />area prior to the final land use. <br />Groundwater Lake and Backfilline <br />During the concurrent reclamation in Phases 2, 3, and 4, the mining cells will be graded to create <br />groundwater lakes. The combined surface area of the groundwater lakes will be no greater than <br />100 acres. Although reclamation during Phase 2 will create a groundwater lake within Ce112, <br />Phase 4 of the reclamation will likely create a groundwater lake that combines Cell 2 and Cell 4. <br />During reclamation and creation of the groundwater lakes, areas of Phases 2, 3, and 4 may also <br />be used as sedimentation basins for the on-site processing facility. <br />Reclamation in Phases 2, 3, and 4 will include backfilling, grading, and seeding to create <br />groundwater lakes from the mining pits. As grading and seeding is completed in each phase, the <br />groundwater lakes will be allowed to fill, reducing the extent of disturbed area during the mining <br />operation. However, the fmal size and extent of the groundwater lakes is not fixed. Although <br />the groundwater lakes will be created and stabilized for final reclamation, they may be partially <br />or completely backfilled to reduce their overall surface area. As overburden and other material <br />becomes available from the site and the adjacent Wattenberg Lakes site, the lakes will be <br />backfilled to create areas for either pastureland with created wetlands (Phases 2 and 3) or future <br />industrial use (Phase 4). Since parts of Ce11s 2, 3, and 4 may also be used as sedimentation <br />basins, it is likely that process fines will also compose a portion of the backfill material during <br />Platte 1'a!!¢y Operation <br />DMG l12 PermitAmendment <br />Page 9 <br />