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Randolph, Nebraska (Section 205) Optimization of Recommended Plan

This project in Randolph, NE aims to mitigate flood risks and protect the community with channel improvement as the recommended alternative. Consideration of economic benefits, costs, and channel dimensions optimization is crucial. The proposed schedule outlines key milestones from public review to project completion in July 2020.

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Randolph, Nebraska (Section 205) Optimization of Recommended Plan

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  1. Randolph, Nebraska (Section 205)Optimization of Recommended Plan Gwyn Jarrett • Project Manager • Omaha District • August 15, 2016

  2. AGENDA • Introductions • Project Authority • Project Location • Alternative Measures • Recommended Alternative • Optimization • Discussion

  3. Section 205 of the Flood Control Act of 1948, as amended. Provides authority for the Corps of Engineers to construct projects (structurally or non-structurally) to reduce damages caused by flooding. Project Authority

  4. Project Location Randolph, NE Location Upper Middle Logan Creek Basin

  5. Purpose and Need • Is there a feasible flood risk management project to protect the community? • Fourteen floods in 100 years. Randolph 1913 Broadway Street 2010

  6. Existing Conditions • Physical Characteristics • Topography, soils • Hydrology • Floodplain • Habitat • Wetlands • Biological Resources • Fish, amphibians, reptiles, mammals, birds • No T&E species

  7. NRCS Soils Survey

  8. Flood Plain Boundary

  9. Middle Logan Creek

  10. Wetlands 2014 National Wetlands Map Downstream – Jackson St. Bridge Downstream – Shoals Road Bridge

  11. Environmental Considerations

  12. Economic Damage Delineations

  13. Problems Opportunities Public awareness Improve Middle Logan Creek Explore upstream storage alternatives Minimal sensitive environment Improve riparian wetlands along Middle Logan creek • Residents at risk • Possible hazards to public safety • Possible hazards to human welfare. • Flood insurance weighing on prospects for economic development, residential resale and quality of life.

  14. Project Objectives • Contribute to National Economic Development. • Regulate flood plain development • - Risk of flooding and increase life protection. • - Potential loss of life. • - Threat to human welfare due • - Flooding Damages • - Need for flood insurance in protected areas

  15. Alternatives Considered

  16. Screening of Alternatives Addresses building. Residual risk remain. Land compatible with flooding. Number of Relocations high. • Alternative 2: Non structural flood proofing and elevation alterative. • Alternative 3 Non Structural Buyout and Relocation. First costs estimated $35M (FY 11) doesn’t include additional infrastructure.

  17. Alternative 4 – Channel Improvement

  18. Alternative 5 – Detention Storage South Branch Middle Logan Creek

  19. Alternative 6 – West Dry Dam and Channel Improvement • Utilize proposed dry dam on Middle Logan Creek west of Randolph coupled with an engineered channel improvement. • Channel improvement portion of this alternative would require replacement of all six bridges. • Buyout or relocation of approximately six residential structures. • Estimated $13M (FY 11 Prices)

  20. Alternative 7 – Levees and Flood Walls • Existing Channel limited capacity • Development along creek. • Natural topography flat; need to extend long distance for tie off. • Buyout and relocation. • Close all 6 bridges; potential for replacement.

  21. Comparison of Alternatives

  22. Economic Benefits and Cost Comparison of Alternatives 6 and 4 (FY 14 Price Levels) Six bridges replaced (43% of project costs) All assumed to use reinforced concrete slab on pier type bridge design. Span limitation of less than 65’. Bridges need multiple spans. Buy out/relocation of 6 properties

  23. Recommended Alternative #4 – Channel Improvement

  24. Channel Improvement Components • Replace 6 bridges with widened structures. • Channel width • Borrow Sources • Disposal Sites • Real Estate

  25. Channel Width 50’ and 75’

  26. Real Estate

  27. Optimization of Selected Plan Evaluation: Channel costs Benefits Range of Channel Dimensions 8,500 CFS Channel with all bridge replacement

  28. Selected Plan Net Benefits, B/C Ratio FY 16 Prices, $1,000s

  29. Cost Apportionment

  30. Proposed Schedule • Public review Oct 2016 • Final report to MSC Dec 2016 • Report approved Jan 2017 • Sign PPA with sponsor April 2017 • Relocation Jan 2018 • Plans and Specs completed Feb 2018 • Advertise and Award Mar/April 2018 • Construction NTP May 2018 • Earth work begin July 2018 • Construction complete July 2020

  31. Discussion

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