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Steelhead Haven

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Steelhead Haven

  1. 1. Steelhead Haven Landslide Fine Sediment Reduction Project Tracy Drury, PE Anchor Environmental L.L.C. Pat Stevenson Stillaguamish Tribe of Indians
  2. 2. Stillaguamish Tribe’s Interests  Chinook Populations at 8% of historic levels  Fine sediments inputs was determined to be a major contributing factor  Success would improve habitat conditions for more than 30 miles downstream
  3. 3. Steelhead Haven Landslide 2004
  4. 4. Historical Perspective 1965 2000
  5. 5. Then came 1967…
  6. 6. Project Planning  Prioritized in the Chinook recovery plans, 1990, 2000, 2005  Began community involvement / public outreach, 1995  Evaluated in the Corps Ecosystem Restoration Plan, 2000  Conceptual Designs Developed, 2001  Funding for design and construction: Salmon Recovery Funding Board (500K) and Centennial Clean Water (500K), 2005
  7. 7. Project Design  Design conducted, 2005-06  Objectives     Maximize sediment storage Promote long-term stabilization of the slide Improve in-stream habitat conditions Constraints  No increase in flood impact to the local community
  8. 8. Preliminary Design Concept
  9. 9. Slide Failure: January 2006
  10. 10. Backwater at low flow
  11. 11. Management Concerns
  12. 12. Management Actions
  13. 13. Opening a channel
  14. 14. Channel Beginnings
  15. 15. January 29th 2006 Channel we cleared Flow through the trees Where the river wants to go
  16. 16. Pre-slide Head scarp Location Post Slide Channel Former Channel Bank 730 Feet
  17. 17. Redesign Conditions
  18. 18. Creek Draining the Slide
  19. 19. Creek Mixing with River
  20. 20. Project Design  Design conducted, 2005-06  Objectives     Maximize sediment storage Promote long-term stabilization of the slide Improve in-stream habitat conditions Constraints  No increase in flood impact to the local community
  21. 21. River 2D Hydraulic Model Output - Depth
  22. 22. River 2D Hydraulic Model Output - Velocity
  23. 23. Expected Change Log Cribwall Placement Expected Channel Migration Expected Head cut
  24. 24. Temporary Bridge
  25. 25. Isolating the River From the Construction
  26. 26. Log Cribwall 1300 feet long, 25 feet high
  27. 27. Ballast Blocks Approximately Every 50 Feet
  28. 28. Backfilled With Woody Debris
  29. 29. What the River Will See
  30. 30. Approximately 20 Acre-feet of Storage
  31. 31. As-Built Conditions
  32. 32. First Flood Event
  33. 33. Channel Migrated Toward the Structure
  34. 34. Migration Progressing Downstream
  35. 35. Take Home Messages  Landslide failure forced redesign to be more highly engineered placement  Constructability was a major decision making factor  The structure was designed to deform and settle as the river undercuts it’s face  Thorough analysis and communications prior to the failure facilitated permit acquisition after the failure
  36. 36. Steelhead Haven Landslide Fine Sediment Reduction Project Tracy Drury, PE Anchor Environmental L.L.C. Pat Stevenson Stillaguamish Tribe of Indians

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