2002-05-22_REVISION - M1977436 - Laserfiche WebLink

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3. Letter from Eric Odel of the Colorado Division of Wildlife dated Apri15, 2002. a) We feel that slopes that aze 3:1 aze too steep to provide much benefit to wildlife habitat. Instead, we encourage much shallower slopes, on the range of 10:1. Creating an undulating shoreline will inherently add diversity to the constructed habitat, which is a beneficial aspect. Creating shallow water habitat far into the reclaimed pond is also beneficial. This will create habitat for aquatic insects, which in turn will attract a different community of migrating wildlife to the area. This shallow water azea should extend approximately 25 feet into the pond form the shoreline. Building small islands in the pond will create refuge for a variety of wildlife, as well. 4. Aggregate Industries states that 4 feet of the berm will be removed to facilitate floodwaters to enter and leave the pit. Please provide a more detailed reclamation plan map that depicts the elevation of the bottom of the pit, the elevation of the riverside berm and the elevation of the spillway in relation to the South Platte River. 5. The operator states that wash fines pumped from the aggregate processing operation into the North Lake will be used to construct the wetlands. Please explain the time frame in which [he azea will be reclaimed to a wetland habitat. Specifically, when the spillway will be constructed, when the azea will be backfilled and graded and when the site will be revegetated with the proposed wetland seed mixture. 6. Aggregate Industries proposes 18" grouted boulders along the pitside of the channel spillways. In accordance with the Technical Review Guidelines for Gravel Mining- Urban Drainage and Flood Control District ("Guidelines"), the grout must have a minimum compressive strength of 2,000 psi. As an alternative, a concrete mix having 3/a- inch maximum aggregate, 4-inch slump and 2,000 psi- 28-day compressive strength may be substituted for grout. In addition, the grout shall be placed in a manner that ensures that all voids within the riprap are filled with grout. Please commit to such specifications, or provide an al[emative method. 7. In the Permit Amendment Application approved by the Division on November 16, 2000, Aggregate Industries states that the operator will avoid disturbing potential Uteiadies-tresses orchid habitat and mining within 300 feet of [he potential Preble's Meadow Jumping Mouse habitat, until the referenced disqualification's and/or trapping studies aze performed. Please inform the Division as to the status of this study and how mining within 100 feet or 200 feet of the South Platte River will impact the Preble's Meadow Jumping Mouse habit and the 300-foot mining offset distance. 8. Aggregate Industries proposes four rundown channels from various drainages that will capture runoff into the pits. Please explain how these channels aze to function in regazd to the water storage reservoirs. Specifically, does Aggregate Industries have the water rights associated with this capture? How will the water exit the pit, and are the spillways designed for such flows? When will such structures be constructed? If cannel spillways aze not constructed (i.e. mining off set distance of 400 feet), how will the rundown water leave the reservoirs? How will existing man made stmctures be impacted by the construction of the rundown channels? Please provide a basis for the various flow rates established for each drainage. Please respond to these items prior to June 20, 2002. )f you have any questions, please do not hesitate to call me at 303-866-4943. .A, Si erely, a Crosby Environmental Protectio cialist Enclosure(s) cc: Cazl Mount; DMG (via electronic mail)