CT2015-052 Feasibility Study 2 - Laserfiche WebLink

Home Browse Search

Augmentation covers the South Arkansas and Poncha Creek to the confluence with the Arkansas River, Cottonwood Creek, Chalk Creek and Cherry Creek, as well as the main- stem Arkansas River from the north boundary of Chaffee County to the District boundary in Fremont County (includes Western Fremont County). A chart showing Upper Arkansas Valley waterways and augmentation area waterways is attached as Appendix D. Proiect Description This project is to rehabilitate the major facility that the District uses to store water to replace depletions under its blanket plan for augmentation. Without rehabilitation this vessel may soon cease to be of any use and would be restricted from use by the State Engineer. This facility is also utilized by the City of Salida and the Town of Poncha Springs for water storage pursuant to agreements with the Upper Arkansas Water Conservancy District. Included with the engineering feasibility study, attached hereto, is a plan for expanding the reservoir by an additional 500 acre feet. The following alternatives were considered: Alternative No.1: Alternative No.2: Alternative No.3: Alternative No.4: No Action; Utilize a diver to inspect and repair gate; Rehabilitate reservoir by pipe rehabilitation and expansion of spillway; or Rehabilitate and expand reservoir. Alternative No. 1 was ruled-out since the need is imminent and no action would risk eventual dam failure, loss of storage and water rights, and an inability to replace depletions under the District's augmentation plan. Alternative No. 2 was ruled-out since this would not rehabilitate the pipe, which has reached the end of its life cycle. Alternative No.3 was not selected since it will not meet long term needs of the South Arkansas drainage. Alternative No. 4 was selected to be completed in two phases. Phase one will satisfy all the needs for continued use of the facility, enlarging the spillway to meet the Inflow Design Flood (IDF) requirements of the Class 1 dam safety requirement of passing 75% of the IDF; rehabilitating the outlet pipe for an additional 50 year life, adding 67 acre feet to the active storage capacity; and installing a filter blanket to mitigate seepage along the right abutment. In addition this will allow re-permitting with the United State Forest Service for use of the reservoir and will include NEP A studies and engineering design and survey for the future expansion. Phase two, expansion, is scheduled to begin after completion of phase one. Water resource studies indicate sufficient water is available to fill the expanded space. The outlet pipe rehabilitation and spillway enlargement in completed in phase one will accommodate the phase two expansion. The cost estimate for this phase two is $2,794,160.00, plus the $515,692.00 of phase one, for a total of $3,309,852.00 for the entire project. uawcd Feasibility Study Rev.doc Page 6 of9