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Tennessee Valley Authority — Technical Presentation (2010)
30 slides from Tennessee Valley Authority's technical presentation, 2010
Slide 1: TVA Kingston Fly Ash Transport and Fate Study
TVA Kingston Fly Ash Transport and Fate Study Post-Spill Site Overview Steve Scott ERDCWES – Principle Investigator Craig Zeller – EPA Region 4 Remediation Project Manager US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 2: The Emory River Impacted by Fly Ash Deposits
TVA Kingston Fly Ash Transport and Fate Study The Emory River Impacted by Fly Ash Deposits US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 3: Immediate Impacts to the Emory River
TVA Kingston Fly Ash Transport and Fate Study Immediate Impacts to the Emory River • Reduced Channel Capacity / Increased Flood Risk (+ 8.0 feet for a 100 year return flood) • Increased River Sediment Transport Capacity / Fly Ash Transport Risk US Army Corps Coastal and Hydraulics Laboratory of Engi
Slide 4: Goals of the Study
TVA Kingston Fly Ash Transport and Fate Study Goals of the Study 2009 - 2010 • Simulate Changes in River Hydrodynamics • Evaluate Fly Ash Erosion and Transport Properties in Laboratory • Simulate Fly Ash Transport and Fate for May 2009 Flood Event • Evaluate The Impact of Dredging on Fly Ash Transpo
Slide 5: Methods
TVA Kingston Fly Ash Transport and Fate Study Methods Modeling • Construct a 2D hydrodynamic / Sediment Transport Model (Watts Bar Reservoir Including the Emory, Clinch, and Tennessee Rivers) • Utilize the Adaptive Hydraulics (AdH) Model Developed at ERDCWES US Army Corps Coastal and Hydraulics Labo
Slide 6: Model Domain
TVA Kingston Fly Ash Transport and Fate Study Model Domain ERM 4.0 Melton Hill CRM 0 Dam TRM 567 ERM 0 CRM 4 Ft Loudoun Dam TRM 530 (Watts Bar Dam) US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 7: Model Domain – Kingston Site
TVA Kingston Fly Ash Transport and Fate Study Model Domain – Kingston Site Weir 1 Plant Intake US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 8: Hydrodynamic Impact: Pre-Spill Velocity – 70,000 cfs
TVA Kingston Fly Ash Transport and Fate Study Hydrodynamic Impact: Pre-Spill Velocity – 70,000 cfs US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 9: Hydrodynamic Impacts: Post-Spill Velocity – 70,000 cfs
TVA Kingston Fly Ash Transport and Fate Study Hydrodynamic Impacts: Post-Spill Velocity – 70,000 cfs US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 10: Comparison of pre and post spill hydrodynamics
TVA Kingston Fly Ash Transport and Fate Study Comparison of pre and post spill hydrodynamics • Fly ash spill increased flooding and transport risk • Fly ash deposits reduced flow capacity of Emory River channel and increased local bed slope • A comparison of pre and post spill hydrodynamics indicate
Slide 11: Fly Ash Erosion / Transport Characterization
TVA Kingston Fly Ash Transport and Fate Study Fly Ash Erosion / Transport Characterization • Laboratory scale SEDflume at ERDCWES • Measures erosion rate of sediment cores • Measures critical shear stress for erosion US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and
Slide 12: SEDflume Description and Operation
TVA Kingston Fly Ash Transport and Fate Study SEDflume Description and Operation US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 13: SEDflume Procedures
TVA Kingston Fly Ash Transport and Fate Study SEDflume Procedures • Formed fly ash cores from TVA samples • Cores were tested after 3, 15, and 35 days of consolidation • Critical bed shear stress as well as erosion rate evaluated US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer
Slide 14: SEDflume Results
⎛τ ⎞ E = 0.00384 ⎜⎜ b −1⎟⎟ 1.759 ⎝τ c ⎠ TVA Kingston Fly Ash Transport and Fate Study SEDflume Results For maximum consolidation (>35 days) • Critical bed shear stress ~ 0.5 Pascal (n/m2) • Erosion rate constant: 0.00384 • Erosion rate exponent: 1.759 • Final form of erosion rate equation: • Consoli
Slide 15: Sediment Transport Modeling
TVA Kingston Fly Ash Transport and Fate Study Sediment Transport Modeling • Model domain from the Kingston site to Watts Bar dam • The ERDC Adaptive Hydraulics model (AdH) was used for the simulations Utilizing the SEDflume Results • Six Fly Ash Grain Sizes were Simulated US Army Corps Coastal and H
Slide 16: Inflowing Hydrographs May 2009
TVA Kingston Fly Ash Transport and Fate Study Inflowing Hydrographs May 3 – May 18 2009 80000 70000 60000 50000 Discharge - cfs Emory River 40000 Clinch River Tennessee River 30000 20000 10000 0 0 2 4 6 8 10 12 14 16 18 Time - days US Army Corps Coastal and Hydraulics Laboratory of Engineers Enginee
Slide 17: Watts Bar Dam Headwater May 2009
TVA Kingston Fly Ash Transport and Fate Study Watts Bar Dam Headwater May 3 – May 18 2009 743 Watts Bar Dam Headwater Elevation - ft 742 741 740 739 0 2 4 6 8 10 12 14 16 18 Time - days US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 18: Fly ash particle size fractions in the bed
TVA Kingston Fly Ash Transport and Fate Study Fly ash particle size fractions in the bed 30 25 Percent of Fly Ash Deposit 20 15 10 5 0 0.0022 0.005 0.012 0.022 0.044 0.16 Fly Ash Particle Size - mm US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 19: Fly Ash Transport and Fate Modeling
TVA Kingston Fly Ash Transport and Fate Study Fly Ash Transport and Fate Modeling • Simulated the May 2009 flood event utilizing SEDflume results • Divided the model domain into 6 analysis reaches • Fly ash fate by grain size was presented for each analysis reach (6 fly ash particle sizes) • Fly ash
Slide 20: Results
TVA Kingston Fly Ash Transport and Fate Study Results • Between 90,000 and 119,000 cubic yards of fly ash mobilized and passed below the site • Most of the fly ash scoured from the lower channel just upstream And downstream of the weir • Up to 5-6 feet of scour occurred in some areas • A maximum of
Slide 21: Fate of Fly Ash by Analysis Reach
TVA Kingston Fly Ash Transport and Fate Study Fate of Fly Ash by Analysis Reach 30 25 Percent Fly Ash Deposited 20 15 10 5 0 ERM 1.3 - 0 CRM 4 - 0 TRM 567 - 560 TRM 560-545 TRM 545 - 530 Watts Bar Dam River Reach US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Deve
Slide 22: Bed Change (Erosion) in the Emory River for the May Event
TVA Kingston Fly Ash Transport and Fate Study Bed Change (Erosion) in the Emory River for the May Event US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 23: Analysis Reaches (Watts Bar dam)
TVA Kingston Fly Ash Transport and Fate Study Analysis Reaches 1 2 3 4 5 6 (Watts Bar dam) US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 24: Bed Change (Deposition) in Analysis Reach
TVA Kingston Fly Ash Transport and Fate Study Bed Change (Deposition) in Analysis Reach 1 US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 25: Bed Change (Deposition) in Analysis Reach
TVA Kingston Fly Ash Transport and Fate Study Bed Change (Deposition) in Analysis Reach 2 US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 26: Bed Change (Deposition) in Analysis Reach 3-6
TVA Kingston Fly Ash Transport and Fate Study Bed Change (Deposition) in Analysis Reach 3-6 US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 27: Sediment Transport Conclusions
TVA Kingston Fly Ash Transport and Fate Study Sediment Transport Conclusions • Model results indicate between 90,000 and 119,000 cubic yards of fly ash transported below the Kingston site during the May 2009 flow event • Coarse sized particles (0.16 – 0.022 mm) deposited in the channel below the sit
Slide 28: Model Simulations to Support Dredging
TVA Kingston Fly Ash Transport and Fate Study Model Simulations to Support Dredging • AdH model was used to evaluate dredging impact on channel transport capacity • Model simulations computed a reduction of fly ash transport for flood events as channel capacity was restored from May 2009 – May 2010
Slide 29: Reduction of Channel Transport Capacity Through Dredging
TVA Kingston Fly Ash Transport and Fate Study Reduction of Channel Transport Capacity Through Dredging 1000 Fly Ash Transport - CY / 1000 70,000 cfs 100 61,000 cfs 10 52000 cfs 50,000 cfs 1 US Army Corps Coastal and Hydraulics Laboratory of Engineers Engineer Research and Development Center
Slide 30: Future Effort – Monitored Natural Recovery in Watts Bar
TVA Kingston Fly Ash Transport and Fate Study Future Effort – Monitored Natural Recovery in Watts Bar • Long term mixing and dilution of fly ash deposits with incoming native sediment load – Simulate burial rates and dilution to background concentrations • The risk associated with fly ash deposits b
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