Revitalization of Rivers in the United States  Using Dam Removal Tim Randle, M.S., P.E., D.WRE. Manager, Sedimentation and...
Dams come in a variety of sizes, they serve a variety of purposes, and they have a variety of impacts.
Benefits of Dams to Society <ul><li>Storage and diversion of water for agriculture, municipal, and industrial use </li></u...
Impacts of Dams on Streams <ul><li>Altered stream flow patterns and temperature (net reductions in stream flow) </li></ul>...
History of U.S. Dam Construction <ul><li>The rate of dam construction for all sizes peaked during the late 1900’s. </li></ul>
Nearly 81,000 major dams in the United States (2005)
Over 750 dams removed in the United States <ul><li>Mostly small dams removed </li></ul><ul><li>Mostly in the states of Pen...
Reasons for Dam Removal <ul><li>Provide for fish and boat passage  </li></ul><ul><li>Revitalize rivers and their ecosystem...
History of U.S. Dam Removal <ul><li>See America Rivers website for bar graph of dam removals </li></ul>
U.S. Dam Removal Science Initiative <ul><li>Heinz Center for Science, Economics and the Environment </li></ul><ul><ul><li>...
U.S. Dam Removal Guidelines <ul><li>American Society of Civil Engineers </li></ul><ul><ul><li>Guidelines for Dam Decommiss...
U.S. Dam Removal Guidelines <ul><li>U.S. Society on Dams </li></ul><ul><ul><li>Guidelines for Dam Decommissioning Projects...
U.S. Dam Removal Initiatives <ul><li>State initiatives  </li></ul><ul><ul><li>Pennsylvania Fish and Boat Commission </li><...
Dam Removal Challenges <ul><li>Political support  </li></ul><ul><ul><li>loss or replacement of project benefits </li></ul>...
Dam Removal Considerations <ul><li>Partial or complete dam removal </li></ul><ul><li>Timing and rate of dam removal </li><...
Why should reservoir sediment be considered?
Potential Sediment Issues <ul><li>Reservoir restoration (veg & topo) </li></ul><ul><li>Temporary increase in suspended sed...
Reservoir Sediment Management Alternatives <ul><li>River Erosion </li></ul><ul><li>Mechanical Removal </li></ul><ul><li>Re...
River Erosion <ul><li>River is allowed to erode a channel through the reservoir sediments </li></ul><ul><li>The rate of er...
Mechanical Removal <ul><li>Sediments are removed from the reservoir </li></ul><ul><li>Options include: </li></ul><ul><ul><...
Reservoir Stabilization
When is reservoir sediment a problem?
Reservoir Sediment Impact Indicators <ul><li>Reservoir size relative to mean annual river flow </li></ul><ul><li>Reservoir...
Reservoir Sediment Trap Efficiency Ratio of reservoir size to mean annual inflow
Case Studies <ul><li>Chiloquin Dam on the Sprague River, Oregon </li></ul><ul><li>Savage Rapids Dam on the Rogue River, Or...
United States of America Chiloquin Dam, OR Savage Rapids Dam, OR Elwha and Glines Canyon Dams, WA Case Studies
Case Study Outline <ul><li>Description of dam </li></ul><ul><li>Reasons for dam removal Rogue's salmon and steelhead trout...
Chiloquin Dam on the Sprague River, Oregon (1.4 km) <ul><li>Constructed in 1914 by U.S. Indian Service for irrigation. </l...
Endangered Fish <ul><li>Lost River sucker  Deltistes luxatus   </li></ul><ul><li>shortnose sucker  Chasmistes brevirostris...
Project Goals <ul><li>Remove dam to restore fish passage and eliminate structural safety concern </li></ul><ul><li>Provide...
Chiloquin Reservoir <ul><li>Relative reservoir size: 0. 00014 </li></ul><ul><li>No reservoir pool fluctuation </li></ul><u...
Chiloquin Dam, July 2008
Chiloquin Dam, August 2008
Chiloquin Dam, August 2008
Chiloquin Dam, August 2008 <ul><li>Only a small amount of sediment </li></ul><ul><li>1,600 submerged logs cut from trees <...
Savage Rapids Dam Rogue River, Oregon (173.2 km) <ul><li>Built in 1921 by the Grants  Pass Irrigation District to divert w...
Savage Rapids Dam Rogue River, Oregon (173.2 km) <ul><li>Concrete diversion dam </li></ul><ul><ul><li>9.1 to 12.4 m high <...
Savage Rapids Project Goals <ul><li>Remove dam to restore fish passage </li></ul><ul><ul><li>Salmon and trout </li></ul></...
Savage Rapids Dam <ul><li>New pumping plant and pipe bridge were constructed prior to dam removal </li></ul>
Savage Rapids Reservoir <ul><li>Relative reservoir size: 0. 0001 </li></ul><ul><li>Reservoir elevation seasonally fluctuat...
Savage Rapids Dam, April 2009
 
 
 
 
Pilot Channel Excavation
 
<ul><li>Total Projects Costs: $40 million </li></ul><ul><ul><li>$5 million for dam removal </li></ul></ul>Savage Rapids Da...
 
8:00  10:00  12:00  14:00  16:00 10 September 2010
Savage Rapids Dam Oct 2009
Savage Rapids Dam Jan 2010
Sediment deposition at the pumping plant intake had to be excavated
Elwha and Glines Canyon Dams, Washington <ul><li>Description of dam </li></ul><ul><li>Reasons for dam removal </li></ul><u...
Elwha River, Washington
Elwha River
Elwha River Seattle Washington Pacific Ocean
Elwha Dam (7.9 km) Glines Canyon Dam (21.7 km) 840 km 2   100 km of tributaries Lower Elwha Tribal Reservation Strait of J...
Elwha River <ul><li>Ave Slope of 0.004 </li></ul><ul><li>River Flow </li></ul><ul><ul><li>Q m  =  42 m 3 /s </li></ul></ul...
Lake Aldwell behind Elwha Dam  <ul><li>10 million m 3   </li></ul><ul><li>3 km long </li></ul><ul><li>90 to 600 m wide </l...
Elwha Dam and Powerplant <ul><li>Constructed in 1913 for hydropower </li></ul><ul><li>32 m high concrete gravity dam </li>...
Lake Mills behind Glines Canyon Dam  <ul><li>50 million m 3   </li></ul><ul><li>3 km long </li></ul><ul><li>300 to 600 m w...
Glines Canyon Dam <ul><li>Constructed in 1927 for hydropower </li></ul><ul><li>Concrete arch dam </li></ul><ul><ul><li>64 ...
Project Goals <ul><li>Remove both Elwha Dams to restore fish passage and ecosystem processes (100 km of river and tributar...
Historic Elwha River before the Dams
 
 
 
 
 
 
 
 
Lake Mills (Glines Canyon Dam) <ul><li>Relative reservoir size: 0.037  </li></ul><ul><li>Run of the river operation </li><...
Reservoir Sedimentation Lake Aldwell Lake Mills Deltas
Reservoir Sedimentation: 16 million m 3 <ul><li>Lake Mills Sediment Volume: </li></ul><ul><li>13 million m 3   </li></ul><...
Reservoir Sediment Grain Size Distribution:   Lake Aldwell  Lake Mills Silt & Clay Silt & Clay Sand Sand Gravel Gravel Cob...
Planning Process <ul><li>The National Park Service is the lead agency for the U.S. Department of the Interior. </li></ul><...
Planning Process <ul><li>The National Park Service completed a programmatic Environmental Impact Statement to determine th...
Planning Process (continued) <ul><li>A second Environmental Impact Statement was completed to determine the best way to re...
Dam Removal and  Sediment Management Plan <ul><li>Beginning in late 2011, concurrently remove Elwha and Glines Canyon Dams...
Fish Windows Dam removal and reservoir drawdown will be temporarily halted during fish window time periods: May - June, Au...
Sediment Management Plan (continued) <ul><li>The Elwha River will be allowed to erode and redistribute the sediments withi...
Sediment Management Plan (continued) <ul><li>The following infrastructure is being built to mitigate project impacts: </li...
New Diversion Weir
Clarifying Tanks Sludge Outfall Diversion Pump Structure Elwha Water Treatment Plant River Flow
Sediment Management Plan (continued) <ul><li>Infrastructure (continued): </li></ul><ul><ul><li>Municipal water treatment p...
Glines Canyon Dam Elwha River, WA
Glines Canyon Dam Removal 15 m 7.6 m
Glines Canyon Dam – Arch Removal (Artist Rendition) Glines Canyon Dam Removal
Project Costs <ul><li>Total Project Costs: $200,000 million </li></ul><ul><ul><li>$20,000 for the removal of both dams </l...
Elwha Dam Removal  (Artist Rendition)
Elwha Dam Removal El. 48.8 m El. 46.3 m El. 43.9 m El. 41.1 m El. 51.8 m El. 54.2 m 9.1 m
Sediment Impact Predictions are Based on Several Investigations <ul><li>1994 Lake Mills Drawdown Experiment </li></ul><ul>...
1994 Lake Mills Drawdown Experiment 6 m over 1 week constant for 1 week
Drawdown Test Measurements <ul><li>Stream gaging of discharge, suspended load, and bedload </li></ul><ul><li>Repeat cross-...
4/09/94  4:02 pm, 179.5 m, 33.7 m 3 /s,  5 mg/L Q s Lower Delta
4/10/94  8:02 am, 178.9 m, 30.9 m 3 /s Lower Delta
04/11/94  8:02 am, 178.0 m, 29.4 m 3 /s Lower Delta
04/12/94  8:02 am, 177.1 m, 30.3 m 3 /s Lower Delta
4/13/94  8:02 am, 176.2 m, 28.6 m 3 /s, 2,010 mg/L Q s Lower Delta
4/14/94  8:02 am 175.3 m, 26.4 m 3 /s, 1,990 mg/L Q s Lower Delta
4/15/94  12:46 pm, 174.6 m,  25.2 m 3 /s,  2,200 mg/L Q s Lower Delta
4/16/94  12:46 pm, 174.3 m, 26.3 m 3 /s, 5,210 mg/L Q s Lower Delta
4/17/94  12:46 pm, 174.3 m,  32.6 m 3 /s Lower Delta
4/18/94  12:46 pm, 572.0 m, 41.9 m 3 /s, 1,720 mg/L Q s Lower Delta
4/19/94  12:46 pm, 572.0 m, 49.8 m 3 /s Lower Delta
4/20/94  12:46 pm, 174.3 m,  43.6 m 3 /s, 1,555 mg/L Q s Lower Delta
4/23/94  10:31 am, 174.3 m,  36.8 m 3 /s Lower Delta
What did we learn? <ul><li>Erosion of the delta was very rapid, even during low river flow. </li></ul><ul><li>The armor la...
Reservoir Erosion Model   Existing sediment Predam river bed Lake Mills Profile
Lake Mills Planform
Lake Mills Elevation
Lake Mills Discharge Water Discharge (m 3 /s)
Lake Mills Sediment Concentration
3.36 km = 10.8 m Horizontal scale = 1 : 310 Chris Bromley  University of Nottingham / Oregon State University University o...
1,070 m = 3.5 m Horizontal scale = 1 : 310 Chris Bromley  University of Nottingham / Oregon State University University of...
Lake Mills Physical Model Experiment Chris Bromley  University of Nottingham / Oregon State University
R11 3x - center 0 of 21
R11 3x - center 3 of 21
R11 3x - center 6 of 21
R11 3x - center 9 of 21
R11 3x - center 12 of 21
R11 3x - center 15 of 21
R11 3x - center 18 of 21
R11 3x - center 21 of 21
 
Erosion Along Delta Margin
Erosion Along the Delta Margin <ul><li>Very unnatural landscape  </li></ul><ul><li>Potential for significant delta erosion...
Erosion Along Center Pilot Channel
Erosion Along Center Pilot Channel
Erosion Along Center Pilot Channel <ul><li>More natural landscape  </li></ul><ul><li>Remaining sediments left in more stab...
Predicted Reservoir Sediment Erosion <ul><li>Erode ¼ to 1/3 of coarse reservoir sediment </li></ul><ul><ul><li>400,000 to ...
Predicted Downstream Fine Sediment Transport <ul><li>Largest peak suspended-sediment concentrations are expected to be bet...
Predicted Downstream  Channel Changes <ul><li>Temporary sediment deposition in river pools </li></ul><ul><li>Straightening...
2001
 
Adaptive Management <ul><li>Real-time monitoring to determine if actual sediment impacts agree with predictions and if new...
Real-Time Monitoring <ul><li>Reservoir sediment erosion and redistribution </li></ul><ul><li>Reservoir hillslope stability...
Possible WEB Camera Views
Conclusions <ul><li>The policy decision to remove a dam is based on the need for action, stakeholder input, technical info...
Conclusions (continued) <ul><li>The level of sediment investigations can be scaled to the ratio of the reservoir sediment ...
Thank you Obrigado!
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Tim randle dam removal in the united states

  1. 1. Revitalization of Rivers in the United States Using Dam Removal Tim Randle, M.S., P.E., D.WRE. Manager, Sedimentation and River Hydraulics Group
  2. 2. Dams come in a variety of sizes, they serve a variety of purposes, and they have a variety of impacts.
  3. 3. Benefits of Dams to Society <ul><li>Storage and diversion of water for agriculture, municipal, and industrial use </li></ul><ul><li>Flood control </li></ul><ul><li>Hydropower </li></ul><ul><li>Navigation </li></ul><ul><li>Lake recreation (boating, fishing, swimming) </li></ul><ul><li>Sediment retention </li></ul>
  4. 4. Impacts of Dams on Streams <ul><li>Altered stream flow patterns and temperature (net reductions in stream flow) </li></ul><ul><li>Decreased oxygen levels </li></ul><ul><li>Blocked migration of fish and other aquatic organisms (turbines hurt fish and increase risk of predation) </li></ul><ul><li>Trapping of sediment, debris, and nutrients </li></ul>
  5. 5. History of U.S. Dam Construction <ul><li>The rate of dam construction for all sizes peaked during the late 1900’s. </li></ul>
  6. 6. Nearly 81,000 major dams in the United States (2005)
  7. 7. Over 750 dams removed in the United States <ul><li>Mostly small dams removed </li></ul><ul><li>Mostly in the states of Pennsylvania, Ohio, Wisconsin, and California </li></ul><ul><ul><li>Also in the states of Rhode Island, Tennessee, Illinois, and Washington </li></ul></ul>
  8. 8. Reasons for Dam Removal <ul><li>Provide for fish and boat passage </li></ul><ul><li>Revitalize rivers and their ecosystems </li></ul><ul><li>Eliminate safety hazards and liability </li></ul>Common Factor <ul><li>In nearly all dam removal cases, the original purpose of the dam was no longer being served or the present function of the dam could be met through other means. </li></ul>
  9. 9. History of U.S. Dam Removal <ul><li>See America Rivers website for bar graph of dam removals </li></ul>
  10. 10. U.S. Dam Removal Science Initiative <ul><li>Heinz Center for Science, Economics and the Environment </li></ul><ul><ul><li>Dam Removal: Science and Decision Making (2002) </li></ul></ul><ul><ul><li>Dam Removal Research Status and Prospects (2003) </li></ul></ul>
  11. 11. U.S. Dam Removal Guidelines <ul><li>American Society of Civil Engineers </li></ul><ul><ul><li>Guidelines for Dam Decommissioning (1997) </li></ul></ul><ul><ul><li>Monograph on Sediment Dynamics upon Dam Removal (2010) </li></ul></ul><ul><li>Aspen Institute (Policy Guideline) </li></ul><ul><ul><li>Dam Removal - A New Option For a New Century (2002) </li></ul></ul>
  12. 12. U.S. Dam Removal Guidelines <ul><li>U.S. Society on Dams </li></ul><ul><ul><li>Guidelines for Dam Decommissioning Projects (2011) </li></ul></ul><ul><li>U.S. Subcommittee on Sedimentation </li></ul><ul><ul><li>Dam Removal Analysis Guidelines for Sediment (2011) </li></ul></ul>
  13. 13. U.S. Dam Removal Initiatives <ul><li>State initiatives </li></ul><ul><ul><li>Pennsylvania Fish and Boat Commission </li></ul></ul><ul><ul><li>Wisconsin Department of Natural Resources </li></ul></ul><ul><li>American Rivers (non-profit organization) </li></ul><ul><ul><li>Technical advice and support for dam removals </li></ul></ul><ul><li>University of California at Berkeley </li></ul><ul><ul><li>Clearing House for Dam Removal (website) </li></ul></ul>
  14. 14. Dam Removal Challenges <ul><li>Political support </li></ul><ul><ul><li>loss or replacement of project benefits </li></ul></ul><ul><li>Funding </li></ul><ul><li>Structural integrity during removal </li></ul><ul><li>Diversion and care of stream </li></ul><ul><li>Reservoir sedimentation and downstream impacts to water quality and morphology </li></ul><ul><li>Uncertainty </li></ul>
  15. 15. Dam Removal Considerations <ul><li>Partial or complete dam removal </li></ul><ul><li>Timing and rate of dam removal </li></ul><ul><li>Stream diversion through, over, or around the dam during its removal </li></ul><ul><li>Sediment erosion or removal </li></ul><ul><li>Flood considerations </li></ul><ul><ul><li>Structural stability during removal </li></ul></ul><ul><ul><li>Avoidance of downstream flood waves </li></ul></ul>
  16. 16. Why should reservoir sediment be considered?
  17. 17. Potential Sediment Issues <ul><li>Reservoir restoration (veg & topo) </li></ul><ul><li>Temporary increase in suspended sediment concentration and turbidity </li></ul><ul><li>Riverbed aggradation, channel adjustments, and increased flood stage </li></ul><ul><li>Sedimentation at water intakes </li></ul><ul><li>Finer bed-material grain size </li></ul><ul><li>Growth in coastal or lake delta </li></ul>
  18. 18. Reservoir Sediment Management Alternatives <ul><li>River Erosion </li></ul><ul><li>Mechanical Removal </li></ul><ul><li>Reservoir Stabilization </li></ul>
  19. 19. River Erosion <ul><li>River is allowed to erode a channel through the reservoir sediments </li></ul><ul><li>The rate of erosion depends on the rate of reservoir drawdown </li></ul><ul><li>Most commonly adopted alternative </li></ul><ul><li>Least cost, but maximum turbidity </li></ul>
  20. 20. Mechanical Removal <ul><li>Sediments are removed from the reservoir </li></ul><ul><li>Options include: </li></ul><ul><ul><li>Hydraulic dredge and slurry pipeline </li></ul></ul><ul><ul><li>Mechanical excavation and truck transport </li></ul></ul><ul><li>High cost, but prevents sediment from entering the downstream river channel. </li></ul>
  21. 21. Reservoir Stabilization
  22. 22. When is reservoir sediment a problem?
  23. 23. Reservoir Sediment Impact Indicators <ul><li>Reservoir size relative to mean annual river flow </li></ul><ul><li>Reservoir level fluctuations </li></ul><ul><li>Reservoir sediment volume relative to the annual sediment transport capacity of the downstream channel </li></ul><ul><li>Concentration of contaminants relative to background levels </li></ul>
  24. 24. Reservoir Sediment Trap Efficiency Ratio of reservoir size to mean annual inflow
  25. 25. Case Studies <ul><li>Chiloquin Dam on the Sprague River, Oregon </li></ul><ul><li>Savage Rapids Dam on the Rogue River, Oregon </li></ul><ul><li>Elwha and Glines Canyon Dams on the Elwha River, Washington </li></ul>
  26. 26. United States of America Chiloquin Dam, OR Savage Rapids Dam, OR Elwha and Glines Canyon Dams, WA Case Studies
  27. 27. Case Study Outline <ul><li>Description of dam </li></ul><ul><li>Reasons for dam removal Rogue's salmon and steelhead trout </li></ul><ul><li>Techniques used </li></ul><ul><li>Community involvement </li></ul><ul><li>Mobilization processes </li></ul><ul><li>Results and Costs </li></ul><ul><li>Lessons learned – Adaptive Management </li></ul>
  28. 28. Chiloquin Dam on the Sprague River, Oregon (1.4 km) <ul><li>Constructed in 1914 by U.S. Indian Service for irrigation. </li></ul><ul><li>Concrete diversion dam </li></ul><ul><ul><li>3.4 m high </li></ul></ul><ul><ul><li>64 m long </li></ul></ul><ul><li>Reservoir pool </li></ul><ul><ul><li>70,000 m 3 </li></ul></ul>
  29. 29. Endangered Fish <ul><li>Lost River sucker Deltistes luxatus </li></ul><ul><li>shortnose sucker Chasmistes brevirostris </li></ul>
  30. 30. Project Goals <ul><li>Remove dam to restore fish passage and eliminate structural safety concern </li></ul><ul><li>Provide water to irrigation district </li></ul><ul><ul><li>Pumping plant constructed </li></ul></ul><ul><li>Avoid downstream sediment impacts to </li></ul><ul><ul><li>Pumping plant </li></ul></ul><ul><ul><li>Aquatic environment </li></ul></ul>
  31. 31. Chiloquin Reservoir <ul><li>Relative reservoir size: 0. 00014 </li></ul><ul><li>No reservoir pool fluctuation </li></ul><ul><li>Sediment volume equivalent to: < 1 year sediment load (39 % silt and clay) </li></ul><ul><li>No contaminants above background levels </li></ul><ul><li>SMALL SEDIMENT PROBLEM </li></ul>
  32. 32. Chiloquin Dam, July 2008
  33. 33. Chiloquin Dam, August 2008
  34. 34. Chiloquin Dam, August 2008
  35. 35. Chiloquin Dam, August 2008 <ul><li>Only a small amount of sediment </li></ul><ul><li>1,600 submerged logs cut from trees </li></ul><ul><li>Low flows following dam removal </li></ul><ul><li>Total project cost of $20 million for dam removal and pumping plant construction </li></ul>
  36. 36. Savage Rapids Dam Rogue River, Oregon (173.2 km) <ul><li>Built in 1921 by the Grants Pass Irrigation District to divert water for irrigation </li></ul><ul><li>Rehabilitated by the U.S. Bureau of Reclamation during the 1960’s </li></ul>
  37. 37. Savage Rapids Dam Rogue River, Oregon (173.2 km) <ul><li>Concrete diversion dam </li></ul><ul><ul><li>9.1 to 12.4 m high </li></ul></ul><ul><ul><li>140 m long </li></ul></ul><ul><li>Reservoir pool </li></ul><ul><ul><li>0.8 km to 4.1 km long </li></ul></ul><ul><ul><li>370,000 m 3 </li></ul></ul>
  38. 38. Savage Rapids Project Goals <ul><li>Remove dam to restore fish passage </li></ul><ul><ul><li>Salmon and trout </li></ul></ul><ul><li>Provide water to irrigation canals along both sides of the river </li></ul><ul><ul><li>Construct pumping plant </li></ul></ul><ul><li>Avoid downstream sediment impacts to </li></ul><ul><ul><li>Pumping plant </li></ul></ul><ul><ul><li>Municipal water intake </li></ul></ul><ul><ul><li>Aquatic environment </li></ul></ul>
  39. 39. Savage Rapids Dam <ul><li>New pumping plant and pipe bridge were constructed prior to dam removal </li></ul>
  40. 40. Savage Rapids Reservoir <ul><li>Relative reservoir size: 0. 0001 </li></ul><ul><li>Reservoir elevation seasonally fluctuates 3.4 m </li></ul><ul><li>Coarse sediment volume equivalent to: 1 to 2 year sediment load (2 % silt and clay) </li></ul><ul><li>No contaminants above background levels </li></ul><ul><li>MODERATE SEDIMENT PROBLEM </li></ul>
  41. 41. Savage Rapids Dam, April 2009
  42. 46. Pilot Channel Excavation
  43. 48. <ul><li>Total Projects Costs: $40 million </li></ul><ul><ul><li>$5 million for dam removal </li></ul></ul>Savage Rapids Dam, Sept 2009
  44. 50. 8:00 10:00 12:00 14:00 16:00 10 September 2010
  45. 51. Savage Rapids Dam Oct 2009
  46. 52. Savage Rapids Dam Jan 2010
  47. 53. Sediment deposition at the pumping plant intake had to be excavated
  48. 54. Elwha and Glines Canyon Dams, Washington <ul><li>Description of dam </li></ul><ul><li>Reasons for dam removal </li></ul><ul><li>Techniques used </li></ul><ul><li>Community involvement </li></ul><ul><li>Mobilization processes </li></ul><ul><li>Results </li></ul><ul><li>Costs </li></ul><ul><li>Lessons learned – Adaptive Management </li></ul>
  49. 55. Elwha River, Washington
  50. 56. Elwha River
  51. 57. Elwha River Seattle Washington Pacific Ocean
  52. 58. Elwha Dam (7.9 km) Glines Canyon Dam (21.7 km) 840 km 2 100 km of tributaries Lower Elwha Tribal Reservation Strait of Juan de Fuca Lake Sutherland Lake Aldwell Port Angeles Lake Mills
  53. 59. Elwha River <ul><li>Ave Slope of 0.004 </li></ul><ul><li>River Flow </li></ul><ul><ul><li>Q m = 42 m 3 /s </li></ul></ul><ul><ul><li>Q 2 = 37 m 3 /s </li></ul></ul><ul><ul><li>Q 100 = 1,270 m 3 /s </li></ul></ul>
  54. 60. Lake Aldwell behind Elwha Dam <ul><li>10 million m 3 </li></ul><ul><li>3 km long </li></ul><ul><li>90 to 600 m wide </li></ul>
  55. 61. Elwha Dam and Powerplant <ul><li>Constructed in 1913 for hydropower </li></ul><ul><li>32 m high concrete gravity dam </li></ul><ul><li>14.8 MW Powerplant </li></ul><ul><li>7.9 km upstream from river mouth </li></ul>
  56. 62. Lake Mills behind Glines Canyon Dam <ul><li>50 million m 3 </li></ul><ul><li>3 km long </li></ul><ul><li>300 to 600 m wide </li></ul>
  57. 63. Glines Canyon Dam <ul><li>Constructed in 1927 for hydropower </li></ul><ul><li>Concrete arch dam </li></ul><ul><ul><li>64 m high </li></ul></ul><ul><ul><li>15 to 46 m wide </li></ul></ul><ul><li>13.3 MW Powerplant </li></ul><ul><li>21.7 km upstream from river mouth </li></ul>
  58. 64. Project Goals <ul><li>Remove both Elwha Dams to restore fish passage and ecosystem processes (100 km of river and tributaries reconnected) </li></ul><ul><li>Continue to provide water for municipal and industrial users </li></ul><ul><li>Continue to provide flood protection </li></ul>
  59. 65. Historic Elwha River before the Dams
  60. 74. Lake Mills (Glines Canyon Dam) <ul><li>Relative reservoir size: 0.037 </li></ul><ul><li>Run of the river operation </li></ul><ul><li>Sediment volume equivalent to: </li></ul><ul><ul><li>85-year coarse-sediment load </li></ul></ul><ul><ul><li>60-year fine-sediment load </li></ul></ul><ul><li>Only iron and magnesium are above background levels </li></ul><ul><li>MAJOR SEDIMENT PROBLEM </li></ul>
  61. 75. Reservoir Sedimentation Lake Aldwell Lake Mills Deltas
  62. 76. Reservoir Sedimentation: 16 million m 3 <ul><li>Lake Mills Sediment Volume: </li></ul><ul><li>13 million m 3 </li></ul><ul><li>½ clay and silt </li></ul><ul><li>½ sand and gravel </li></ul><ul><li>Lake Aldwell Sediment Volume: </li></ul><ul><li>3 million m 3 </li></ul><ul><li>2/3 clay and silt </li></ul><ul><li>1/3 sand and gravel </li></ul>
  63. 77. Reservoir Sediment Grain Size Distribution: Lake Aldwell Lake Mills Silt & Clay Silt & Clay Sand Sand Gravel Gravel Cobble Cobble
  64. 78. Planning Process <ul><li>The National Park Service is the lead agency for the U.S. Department of the Interior. </li></ul><ul><li>Bureau of Reclamation was charged with engineering the dam removal and sediment management. </li></ul>
  65. 79. Planning Process <ul><li>The National Park Service completed a programmatic Environmental Impact Statement to determine the best way to achieve river restoration. </li></ul><ul><li>The Record of Decision was to remove both dams. </li></ul>
  66. 80. Planning Process (continued) <ul><li>A second Environmental Impact Statement was completed to determine the best way to remove the dams and manage the reservoir sediment. </li></ul><ul><li>The Record of Decision was to concurrently remove both dams in controlled increments and allow the Elwha River to erode a portion of the sediments from both reservoirs. </li></ul>
  67. 81. Dam Removal and Sediment Management Plan <ul><li>Beginning in late 2011, concurrently remove Elwha and Glines Canyon Dams over a two and three-year period. </li></ul><ul><li>This rate is considered fast enough to limit impacts to a few year classes of fish, but slow enough that downstream impacts can be tolerated. </li></ul>
  68. 82. Fish Windows Dam removal and reservoir drawdown will be temporarily halted during fish window time periods: May - June, Aug - Sep, Nov - Dec
  69. 83. Sediment Management Plan (continued) <ul><li>The Elwha River will be allowed to erode and redistribute the sediments within each reservoir. A portion of the reservoir sediments will be eroded to the sea. </li></ul><ul><li>Adaptive Management will be applied to insure impacts do not exceed the capacity of mitigation measures. </li></ul>
  70. 84. Sediment Management Plan (continued) <ul><li>The following infrastructure is being built to mitigate project impacts: </li></ul><ul><ul><li>A diversion weir and engineered riffle provide river water for industrial and municipal use and allow fish passage. This facility replaces the old rock diversion dam, which had fish passage problems. </li></ul></ul><ul><ul><li>Water treatment plant near the river will pre-treat diverted water for existing water users. </li></ul></ul>
  71. 85. New Diversion Weir
  72. 86. Clarifying Tanks Sludge Outfall Diversion Pump Structure Elwha Water Treatment Plant River Flow
  73. 87. Sediment Management Plan (continued) <ul><li>Infrastructure (continued): </li></ul><ul><ul><li>Municipal water treatment plant. </li></ul></ul><ul><ul><li>Industrial water treatment plant. </li></ul></ul><ul><ul><li>Flood protection structures: </li></ul></ul><ul><ul><ul><li>increased height of existing levees and </li></ul></ul></ul><ul><ul><ul><li>new levees and dikes </li></ul></ul></ul>
  74. 88. Glines Canyon Dam Elwha River, WA
  75. 89. Glines Canyon Dam Removal 15 m 7.6 m
  76. 90. Glines Canyon Dam – Arch Removal (Artist Rendition) Glines Canyon Dam Removal
  77. 91. Project Costs <ul><li>Total Project Costs: $200,000 million </li></ul><ul><ul><li>$20,000 for the removal of both dams </li></ul></ul>
  78. 92. Elwha Dam Removal (Artist Rendition)
  79. 93. Elwha Dam Removal El. 48.8 m El. 46.3 m El. 43.9 m El. 41.1 m El. 51.8 m El. 54.2 m 9.1 m
  80. 94. Sediment Impact Predictions are Based on Several Investigations <ul><li>1994 Lake Mills Drawdown Experiment </li></ul><ul><li>Reservoir sediment erosion models: </li></ul><ul><ul><li>Numerical model </li></ul></ul><ul><ul><li>Physical model </li></ul></ul><ul><li>Downstream sediment transport numerical model (HEC-6) </li></ul><ul><li>Monitoring </li></ul>
  81. 95. 1994 Lake Mills Drawdown Experiment 6 m over 1 week constant for 1 week
  82. 96. Drawdown Test Measurements <ul><li>Stream gaging of discharge, suspended load, and bedload </li></ul><ul><li>Repeat cross-section measurements </li></ul><ul><li>Time lapsed photography </li></ul><ul><li>Aerial photography </li></ul><ul><li>Bed material size measurements and mapping </li></ul>
  83. 97. 4/09/94 4:02 pm, 179.5 m, 33.7 m 3 /s, 5 mg/L Q s Lower Delta
  84. 98. 4/10/94 8:02 am, 178.9 m, 30.9 m 3 /s Lower Delta
  85. 99. 04/11/94 8:02 am, 178.0 m, 29.4 m 3 /s Lower Delta
  86. 100. 04/12/94 8:02 am, 177.1 m, 30.3 m 3 /s Lower Delta
  87. 101. 4/13/94 8:02 am, 176.2 m, 28.6 m 3 /s, 2,010 mg/L Q s Lower Delta
  88. 102. 4/14/94 8:02 am 175.3 m, 26.4 m 3 /s, 1,990 mg/L Q s Lower Delta
  89. 103. 4/15/94 12:46 pm, 174.6 m, 25.2 m 3 /s, 2,200 mg/L Q s Lower Delta
  90. 104. 4/16/94 12:46 pm, 174.3 m, 26.3 m 3 /s, 5,210 mg/L Q s Lower Delta
  91. 105. 4/17/94 12:46 pm, 174.3 m, 32.6 m 3 /s Lower Delta
  92. 106. 4/18/94 12:46 pm, 572.0 m, 41.9 m 3 /s, 1,720 mg/L Q s Lower Delta
  93. 107. 4/19/94 12:46 pm, 572.0 m, 49.8 m 3 /s Lower Delta
  94. 108. 4/20/94 12:46 pm, 174.3 m, 43.6 m 3 /s, 1,555 mg/L Q s Lower Delta
  95. 109. 4/23/94 10:31 am, 174.3 m, 36.8 m 3 /s Lower Delta
  96. 110. What did we learn? <ul><li>Erosion of the delta was very rapid, even during low river flow. </li></ul><ul><li>The armor layer was mobilized by head-cut erosion. </li></ul><ul><li>Both vertical incision and lateral erosion processes were very important. </li></ul><ul><li>The eroding delta sediments completely re-deposited across the width of the receded reservoir. </li></ul>
  97. 111. Reservoir Erosion Model Existing sediment Predam river bed Lake Mills Profile
  98. 112. Lake Mills Planform
  99. 113. Lake Mills Elevation
  100. 114. Lake Mills Discharge Water Discharge (m 3 /s)
  101. 115. Lake Mills Sediment Concentration
  102. 116. 3.36 km = 10.8 m Horizontal scale = 1 : 310 Chris Bromley University of Nottingham / Oregon State University University of Minnesota Saint Anthony Falls Laboratory
  103. 117. 1,070 m = 3.5 m Horizontal scale = 1 : 310 Chris Bromley University of Nottingham / Oregon State University University of Minnesota Saint Anthony Falls Laboratory
  104. 118. Lake Mills Physical Model Experiment Chris Bromley University of Nottingham / Oregon State University
  105. 119. R11 3x - center 0 of 21
  106. 120. R11 3x - center 3 of 21
  107. 121. R11 3x - center 6 of 21
  108. 122. R11 3x - center 9 of 21
  109. 123. R11 3x - center 12 of 21
  110. 124. R11 3x - center 15 of 21
  111. 125. R11 3x - center 18 of 21
  112. 126. R11 3x - center 21 of 21
  113. 128. Erosion Along Delta Margin
  114. 129. Erosion Along the Delta Margin <ul><li>Very unnatural landscape </li></ul><ul><li>Potential for significant delta erosion after dam removal </li></ul><ul><li>Different result than numerical model </li></ul>
  115. 130. Erosion Along Center Pilot Channel
  116. 131. Erosion Along Center Pilot Channel
  117. 132. Erosion Along Center Pilot Channel <ul><li>More natural landscape </li></ul><ul><li>Remaining sediments left in more stable condition </li></ul><ul><li>Model result are very similar to numerical model </li></ul>
  118. 133. Predicted Reservoir Sediment Erosion <ul><li>Erode ¼ to 1/3 of coarse reservoir sediment </li></ul><ul><ul><li>400,000 to 600,000 m 3 of gravel </li></ul></ul><ul><ul><li>1,300,000 to 1,800,000 m 3 of sand </li></ul></ul><ul><li>Erode ½ to 2/3 of fine sediment </li></ul><ul><ul><li>4,000,000 to 5,000,000 m 3 of silt and clay </li></ul></ul>
  119. 134. Predicted Downstream Fine Sediment Transport <ul><li>Largest peak suspended-sediment concentrations are expected to be between 10,000 and 40,000 ppm </li></ul><ul><li>Turbidity is expected to exceed water quality standards (greater than 5 NTU’s or 10% more than natural upstream turbidity) during ¾ of the dam removal period </li></ul>
  120. 135. Predicted Downstream Channel Changes <ul><li>Temporary sediment deposition in river pools </li></ul><ul><li>Straightening of sinuous river alignment </li></ul><ul><li>Aggradation of some riffles </li></ul><ul><li>Temporary braided river channel and channel widening </li></ul><ul><li>Aggradation of sand and gravel could increase 100-year flood stage by up to 1 m </li></ul>
  121. 136. 2001
  122. 138. Adaptive Management <ul><li>Real-time monitoring to determine if actual sediment impacts agree with predictions and if new water treatment plants and flood control levee modifications can accommodate those impacts. </li></ul><ul><li>Corrective actions can include: </li></ul><ul><ul><li>More frequent and detailed monitoring </li></ul></ul><ul><ul><li>Local treatment of bank erosion problems </li></ul></ul><ul><ul><li>Slower rate of dam removal </li></ul></ul><ul><ul><li>Temporary halt of dam removal </li></ul></ul>
  123. 139. Real-Time Monitoring <ul><li>Reservoir sediment erosion and redistribution </li></ul><ul><li>Reservoir hillslope stability </li></ul><ul><li>Stream gaging of discharge, turbidity, suspended-sediment concentration, and bedload </li></ul><ul><li>Riverbed aggradation and flood stage </li></ul><ul><li>Aquifer characteristics </li></ul><ul><ul><li>water table and well yields </li></ul></ul><ul><li>River channel planform and geometry </li></ul><ul><li>Large woody debris </li></ul><ul><li>Web cameras </li></ul>
  124. 140. Possible WEB Camera Views
  125. 141. Conclusions <ul><li>The policy decision to remove a dam is based on the need for action, stakeholder input, technical information, and available funding. </li></ul><ul><li>Technical information needs to consider removal of the structure, alternative ways of meeting remaining purposes of the dam, sediment management, and mitigation for impacts. </li></ul>
  126. 142. Conclusions (continued) <ul><li>The level of sediment investigations can be scaled to the ratio of the reservoir sediment volume to the annual sediment transport capacity of the downstream channel. </li></ul>
  127. 143. Thank you Obrigado!

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