2007-09-11_REVISION - M1997054 (2)

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compacted earth fill, protected by riprap. The affect of the bridge construction on riparian habitat was minimal. In 1997, the U. S. Army Corps of Engineers (Corps) and the Colorado Division of Wildlife (DOW) reviewed the bridge construction plans. The Division, DOW, and the Corps were satisfied that the bridge plans were adequate to handle the appropriate storm events. No further work has been performed for this amendment regarding the bridge crossings. The previously amended application delineated the 100-year flood plain of Tallahassee Creek. All mining activities and structures (except the bridge abutments and approaches) were located outside the flood plain. However, this new delineation was never approved by FEMA so this amendment will introduce a revised delineation of that floodplain. A Letter of Map Revision (CONK) will be submitted to the Federal Emergency Management Agency (FEMA) in the summer of 2007. SAND AND GRAVEL MINING PLAN This amendment proposes a new mining limit that extends the previous one to the west to include an additional 12 acres and a new mining depth down to bedrock (approximately 60 feet) across the entire length of the pit and through the processing facility. The mining process involving screens and a crusher and the mining hours of operation remain unchanged from the approved mining plan. Mine Phasing The mining will continue in the current westward direction and mining below the groundwater table and down to the underlying bedrock will begin directly after DRMS approval. The 60-ft deep mining will begin along the northern boundary and continue around the sand and gravel pit in acounter-clockwise direction. This will allow for concurrent reclamation of the clay liner and shell material and will limit the azea of disturbance at any one time. Once the west side has been mined, the mining will continue east along the north boundary. The last area mined will be the location of the processing plant. As the mining and reclamation progress, topsoil placement and seeding will follow. Time estimates to complete all mining is approximately 8-12 years, with reclamation to take place concurrently with mining activities and be complete in approximately 15 yeazs. Mining Methods The current processing plant includes wet and dry screening of the sand and gravel. The processing plant was established at an elevation approximately 8 feet below the natural grade level. This, along with the temporary berms, has helped minimize light and noise impacts to surrounding areas. Mined material will be sized and shaped with screens and crushers. The sand and gavel will be mined with a combination of tracked and rubber-tired heavy construction equipment including scrapers, dozers, front end loaders and haul trucks. The mining face will be a nearly vertical to 1/2H:1 V slope (as is currently done) with a 20-foot mining bench approximately 40 feet beneath the existing ground surface. Dewatering trenches will be excavated azound the perimeter of the mined azea. The active mining face will be no more than 2,000 feet in length. Once approximately 10-15 acres of the bedrock is exposed along the northwest perimeter, reclamation will begin as discussed in the reclamation plan. Range Aggregates, LLC- Parkda[e Quarry DMG 111 Permit Amendment Page 11