Laserfiche WebLink
i • <br /> Because of the open space location,project partners were able to design the most natural <br /> channel possible in both appearance—by using existing materials and vegetation—and in <br /> function—by allowing the river to overflow its banks and migrate if needed. The only <br /> armoring needed was at the upstream and downstream connections. <br /> Material Storage and Sorting and Tailings Mitigation: Meanwhile, crews worked with a <br /> loader at the new upstream material storage site to separate tailings and begin <br /> construction of the tailings mitigation site and prepare the remaining materials for <br /> placement into the old channel. The tailings mitigation plan included removal of the tailings <br /> and subsurface soils within the new channel and within 50 feet of the edge of the new <br /> channel at the upstream end of the project,where more lateral migration is anticipated. <br /> Downstream tailings within the channel and within 20 feet of the channel were also <br /> removed. The tailings were then consolidated, capped with organic material and re- <br /> vegetated with native grasses and forbs per the project plans. Established vegetation and <br /> soil cover will reduce potential infiltration. Consolidating and capping the tailings in the <br /> project reach will result in significant improvement over the previous on-the-surface, <br /> exposed condition.This mitigation approach was developed based on laboratory <br /> evaluations of the tailings sampled from within the project reach and ERC's direct <br /> experience with tailings mitigation in other parts of the state. <br /> Sewer Line Improvements: The Town's main sewer line follows the abandoned railroad <br /> grade along the old channel through Reach One. The line continues through the railroad <br /> grade to the sewer treatment plant downstream of the Valley Floor property. The old <br /> channel ran on the south side of the line, and the new channel would breach the railroad <br /> grade and sewer line at its upstream and downstream connections to the existing channel. <br /> Going under the channel proved the most viable option, so the goal was to design a gravity- <br /> fed (non-mechanical, non-electronic) system. The engineer designed a siphon system using <br /> spiral tubes to create momentum to carry sludge down and up again at each crossing. Local <br /> public works officials and an independent third-party engineer were consulted to confirm <br /> the design and observe the installation to ensure the system would work for this specific <br /> location and application.The final design used concrete-encased pipes trenched 4 feet <br /> under the new channel, leaving and reentering through vaults (measuring 5'W x 101 x 5'H) <br /> buried on each side of the crossing in the railroad grade.A pipeline system between the <br /> vaults, using three pipes sized to accommodate Telluride's population (2,500 to over <br /> 20,000 at times),will ensure the flow capacity needed for the siphon action. This <br /> construction required deeper excavation immediately adjacent to the existing channel and <br /> constant bypass pumping. <br /> Nature's Engineers: ERC consulted with Bio-Logic Environmental's wildlife biologists to <br /> ensure minimal disturbance of the resident beaver populations on the Valley Floor. <br /> Although it was determined that the family had deserted the lodge within the largest and <br /> oldest pond complex in the downstream project area, additional families were living in and <br /> building lodges at other locations around the Valley Floor and frequently visited the project <br />