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the mining activities before mining in the Area is complete.Concurrent reclamation will be practiced when the <br /> highwall reaches the mine limit. During the flood season April 1 through September 30 and when the highwall is <br /> within 400 feet or less of the river the highwall will be no steeper then 3H:1 V. <br /> As mining progresses,topsoil,overburden,and non-marketable materials will be removed and stockpiled for use in <br /> reclamation activities. In the South Area,topsoil and overburden will first be stockpiled along the west and north <br /> sides of the South Area,or, used for screening during the South Area mining activities. Once mining in the South <br /> Area is complete,overburden from the West Area may be transported across Highway 7 to backfill the South Area. <br /> During mining in the West and East Areas,topsoil will be segregated and stockpiled in the locations shown on Exhibit <br /> C Mining Maps, i.e.outside of the Floodway. As mining progresses,overburden will be taken directly to mined out <br /> slopes for use in reclamation. Topsoil and overburden stockpiles will be configured to have side-slopes no steeper <br /> than 3H:1 V. If the stockpiles are inactive for more than one growing season,such as the stockpiles used for <br /> screening,they will be seeded with the fast-growing grass seed mixture below. <br /> Stockpile Grass Seed Mixture <br /> Grass Species Rate <br /> (#PLSlacre) <br /> Luna Pubescent Wheatgrass 15.0 <br /> Amur Intermediate Wheatgrass 15.0 <br /> Rates are for broadcast seeding. <br /> Other than those used for screening, long-term stockpiles are not anticipated. Temporary stockpile materials will <br /> continually be used for reclamation and the stockpiles will likely be disturbed on a frequent basis and seeding the <br /> stockpiles may not be practical during the operation. If stockpile seeding is not used,surface roughening will be <br /> maintained to limit wind and water erosion. <br /> Most of the proposed Tucson South Resource Permit Boundary Area is within the regulatory floodplain of South <br /> Platte River. Because of floodplain regulatory restrictions,stockpiling will occur within a mining Area whenever <br /> possible with the top of stockpile elevation lower than the pre-project grade. Stockpiles within the modeled floodplain <br /> above the existing ground surface will generally be created parallel to potential South Platte River flood flows. The <br /> stockpiles will be no longer than 300 feet,with minimum spacing of 100 feet between stockpiles for flood flows to <br /> pass(see Exhibit C, Mining Maps). The screening stockpiles along Highway 7 as indicated by modeling,are located <br /> in areas where placement is not expected to impact floodplain water surface elevations. Consequently there is no <br /> restriction on length or orientation. The impacts of stockpiles on floodplain water surface elevations is presented in <br /> the Floodplain Use Permit application submitted to Adams County in support of the County Special Use Permit <br /> application. <br /> Ineffective flow areas are also known as"backwater"areas. These areas flood when the water surface elevation <br /> increases,but do not actively convey flows downstream. Ineffective flow areas have essentially no flow velocity. <br /> Ineffective flow areas are typically found upstream and downstream of bridges and culverts as flow contracts and <br /> expands through the opening. Because they do not convey flow downstream,these areas can be filled or altered <br /> without impacting flood water surface elevations. Stockpiles in other locations,which are in active flow areas,are <br /> oriented to be parallel to the direction of flow to minimize impacts to the flood water surface elevations. Since the <br /> Aggregate Industries Tucson South Resource <br /> Permit#M-2004-044112 Permit Amendment <br /> Page D-5 <br />