Expiration date: 7/29/2024
Central Public Power & Irrigation District (CNPPID) is proposing to remove sediment from upstream of its Supply Canal Diversion Dam and deposit it downstream into the Platte River when flow is greater than 150 cfs. The proposed project will also include dredging and discharging into temporary off-site containment areas when the Platte River flow is less than 150 cfs. Sediment from the East Dredge Containment Area will be mechanically discharged into the Platte River when flows are conductive. To improve conveyance downstream of the Diversion Dam, the Platte River channel will be re-directed with the installation of a wing dike to the East Dredge Containment Area for managed mechanical discharge. The proposed wing dike will be 700-foot-long with a 15-foot top width. The wing dike will direct north gate flow from 0 to 3,000 cfs to the East Dredge Containment Area along the south bank of the Platte River via a 1,850-foot-long, 90-foot-wide constructed diversion channel. The wing dike will have a variable bottom width not to exceed 60 feet. The East Dredge Containment Area will also be expanded to allow for greater on-site containment. Annual sand aggradation is anticipated to occur within the constructed channel. To maintain flows, annual mechanized maintenance of the channel will be required to remove aggraded sand/sediment and maintain a 90-foot bottom width and a 0.1% slope, as the depth varies along the channel.