This is a multi-year project to repair a diversion structure which is preventing a head-cut from continuing upstream.
Objectives: 1) Reduce or halt erosion occurring at the headcut. 2) Halt the headcut progression which may infringe on and destabilize upstream railroad, highway, interstate, and mine PMT. 3) Halt the headcut progression into the upstream channel morphology and riparian regime.
Strategies:
• Detailed runoff and flow analysis to the headcut location for the associated 830 square mile drainage area.
• Selection of the acceptable design event/peak design flow for the structure.
• Determination of all permitting requirements, timeframes, and responsibilities.
• Evaluation of the native material stability and excavation characteristics.
• Inclusion of a WGFD endorsed fish migration barrier in the ultimate design.
• Determination of the definition of “channel relocation” as it applies to the approach set forth in Alternatives 3 and 4.
• Selection of a preferred design.
• Determination of the minimum channel length, slope, width, riprap size, etc. to meet the preferred design alternative.
• Detailed permitting plan and construction design suitable for implementation.
• Detailed project cost estimate.
