Forensic Investigations of Dam Failures Paul C. Rizzo October 7,2010 Case Histories
• A few introductory notes: – All major litiga tion on each projtject is compltdleted –All information reported here is in the public domain • Dam Failures discussed today –The “Classics” plus –Taum Sauk – Silver Lake – Saluda Dam –Swinging Bridge Click to edit Master title style – Will not talk about Tampa Bay, Lake Dehli, Levee Failures
2 References
• Dr. A.J. “Skip” Hendron • Brian Green • Prof. J. David Rogers • Euler Cruz & Rafael Cesário • Dr. David Petley
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3 Definition of Failure
• Failure at a dam is “an uncontrolled release of water” • Causes of Failure – Overtopping –the most common cause – Piping thru Embankment –2nd!! –Piiiping thru Foundidation –3rd!! – Foundation Degradation •Karst development • Lique fac tion •Loss of fines over time – Earthquakes – ground motion and faults Click to edit Master title style – Failure of gates, stoplogs, flashboard malfunction, penstocks, tunnels, and reservoir slopes
4 Some “Classics” We learn from out mistakes!!
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5 Classic Failures
• Had a major impact on dam or hydro engineering
• Had a major impact on dam safety legislation and dam safety regulations
Click to edit Master title style • Had a major impact on society
6 Folsom Dam Folsom, California July 17, 1995 Click to edit Master title style
7 Folsom Dam – “Before”
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8 Folsom Dam – “After”
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9 Folsom Dam ‐ 1995
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10 Folsom Dam
• Increased profession’s awareness of the need for maintenance and inspection of auxiliary features associated with a dams
• Changed FERC’sClick to edit Ins Masterpection title style Guides
11 Shih Kang Dam Taiwan September 21, 1999 Click to edit Master title style
12 Shih Kang Dam –Taiwan Impact of building a dam over a fault
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13 Shih Kang Dam ‐ Taiwan
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14 Shih Kang Dam ‐ Taiwan
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15 Austin ((yBayless) Dam Austin, Pennsylvania September 30, 1911 Click to edit Master title style
16 Austin Dam – “Before”
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17 Austin Dam – “After”
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18 Austin Dam
• Destroyed the myth that “gravity dams can’t fail” • Illustrates the need for detailed, comprehensive foundation investigations and foundation preparation • Illustrates the need for temperature expansion/contractionClick to edit Master joints title style in gravity dams
19 ViVaiont Dam Italy October 1963
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20 Vaiont Dam – Double Arch 245m (800) ft high
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2121 Village of Longarone “Before” Vaiont Dam Failure
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22 The Vaiont Dam Disaster
• Dam completed and filled • Reservoir cycled up and down several times over three years • Left Reservoir Slope Failed catastrophically
• Within 30 – 40 seconds, some 270 million m3 of rock crashed into the reservoir. • Resulting waveClickovertopped to edit Master titledam style by about 100 – 150 m.
23 Vaiont Dam – Reservoir Slope Failure
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24 Longarone Village “After” Vaiont Dam Failure
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25 Vaiont Dam at the Top
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26 Teton Dam Teton, Idaho June 5, 1976
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27 Teton – “Before”
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28 Start of Piping – June 5 –7:00 AM
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29 June 5 ‐11:20 AM
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30 June 5 – 11:50 AM (Crest still intact)
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31 June 5 – 11:50 AM (Crest now eroding)
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32 June 5 – 12:00 noon (Crest lost – maximum flood)
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33 Lessons Learned
• Compaction is extremely important throughout the dam and especially at the abutments • Grout Curtains are critical to prevent piping • Keyway design is critical • Filters are a key feature to resist piping Click to edit Master title style (When in doubt, add a filter)
34 Compaction Against Right Abutment
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35 Compaction Equipment after Change
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36 Sayano‐Shushenskaya Khkhakassia, Russia August 17, 2009
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37 Accident at Russia’s Largest Hydroelectric Power Station
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38 Dam Penstocks Spillway Units 10 9 8 7 6 5 4 3 2 1
Powerhouse Control Building
39 40 The Accident – 2009 Aug 17
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4141 Before the Accident
Crane
Power Units
Air‐Oil TanksClick to edit Master title style
Sump Tank Governor 4242 Pumps Generators floor After the Accident
Sump Tank
Air‐Oil Tanks Floor
Unit 2
Click to edit Master title style Colector Ring Crosshead – Unit 2
Unit 1
4343 Generator floor General View
Floor
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4444 General View
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4545 Before the Accident
Generator Rotor –Unit 5
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The accident started here 4646 Generator Runner Sump Tank (turned) Air‐Oil Tank
Crosshead
47 After the Accident
Unit 7: destroyed
Click to edit Master title style Unit 9: destroyed
4848 Unit 9
Unit 7
49 50 51 Unit 2
Units 7 and 9
52 Flood Flood
53 Lower Van Norman Dam Los Angeles, California February 9, 1971
A Classic thatClick to edit was Master title not style a failure!
54 Lower Van Norman February 9, 1971
• Lower Van Norman Dam was bu ilt by the Cityof LtLost AlAngeles as part of the Los Angeles Aqueduct in 1916 – 1918, using the hydraulic fill and puddledClick to edit fill Master techniques. title style A rolled fill addition was placed in 1924. • The embankment failed during the February 9, 1971 M. 6.7 San Fernando Earthquake, but no water was released.
55 Lower Van Norman
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56 Lower Van Norman Forerunner to Modern Liquefaction Analysis Susceptibility to Liquefaction
Click to edit Master title style •Careful forensic evaluations by the geotechnical engineering group at U.C. Berkeley unraveled the dam’s failure by liquefaction of a zone of low density sandy hydraulic fill, shown in blue in the above sections. •The Stat esubtlbsequentlysltdlated 30 other hdhydrauli c fill dams for retrofitti ng between 1973 – 75. 57 Swinggging Bridge Dam Sullivan County, New York May 5, 2005 Click to edit Master title style
58 SwingingSwinging Bridge Bridge Dam Dam Cross Cross Section Section
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59 Swinging Bridge Dam
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60 Swinging Bridge Dam
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61 Swinging Bridge Dam
• Over time leaks developed • Fines transported to penstock during dewatering • Sinkholes developed on crest • Reservoir drained • Penstock & Unit abandoned • Dam repaired and refilled (3 yr shutdown) Click to edit Master title style
62 Silver Dam Lake Upper Peninsula, Michigan May 2003
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63 Silver Lake Dam Dead River Hydroelectric Project
• MtiMountain Top Storage LkLake – Main Concrete Dam with Spillway & Outlet Pipe/Gate Control – Auxiliary Dams and Dikes – Emergency Spillway with Erodible Fuse plug
• May, 2003 –snowmelt, Gate Control not Activated • Fuse Plug Eroded • Main Dam Overtopped – minimal damage • Dam No. 2 overtopped & eroded away entirely Click to edit Master title style • Failure drained approximately 25,000 acre feet of water from Silver Lake Reservoir • $100 million damage – no fatalities
64 Silver Lake – Overtopping of Main Dam
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65 Saluda Dam Columbia, South Carolina Rehabilitation Click to edit Master title style
66 Saluda Dam A Failure that was Prevented!
SALUDA RIVER WATEREE RIVER
COLUMBIA
SANTEE LAKE RIVER MURRAY
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67 Aerial View of Saluda Dam
NORTH Intake Towers Spillway
McMeekin Station
Saluda Hydro
Click to edit Master title style Ash Ponds & Bush Landfill River Rd.
68 Saluda Dam
Existing Dam
Hydroelectric Plant Lake Murray
Lake Area 78 square miles Lake Capacity 1,600,000 acre feet Dam Length Click to edit Master title7,800 style feet Max Dam Height 200 feet Powerhouse Capacity 260 MW Original Construction Hydraulic Fill Original Completion 1930 69
OriginalOriginal Dam Dam Construction Construction
• Dam was constructed 1927 ‐ 1930 • 11,000,000 cy‐‐semi‐hydraulic method
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7085 As‐Built Dam Configuration
• Semi‐Hydraulic Fill • Most soils “Dumped” • No compaction
Rolled Core Washed Fill Rip Rap Washed Fill Unwashed Fill Click to edit Master title style
Unwashed Fill Sluiced Core Residual Soil
71 Dynamic Stability Analysis
• Liquefaction Evaluation of Saluda Dam
– Earthquake record selection – Liquefaction methodology
• Post‐Seismic Stability Analysis
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72 Liquefaction Analysis
Factor of Safety against Liquefaction (FSL)
-0.02 0.32 0.66 1.00 1.33 1.67 2.00 3.78 5.57 7.35
Extensive Liquefaction,Click to edit Master Post title‐Seismic style FS < 1
73 Section AA’ (typ.)
Lower Bound
-0.03 0.31 0.66 1.00 1.33 1.67 2.00 3.51 5.02 6.53
BtBest Case
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-0.06 0.30 0.65 1.00 1.33 1.67 2.00 3.96 5.92 7.88
74 Remediation Concept
Competent Rock
Rockfill Dam Click to edit Master title style • Length 5,100 feet • Max. Height 200 feet
75 Remediation Concept
RCC Dam Click to edit Master title style • Length 2,200 feet • Max. Height 210 feet
76 Taum Sauk Upper Reservoir Lesterville, Missouri December 15, 2005
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77 Taum Sauk on December 14, 2005
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78 Taum Sauk on December 15, 2005 Release of 114.4 Billion Gallons of Water
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79 Original Rockfill Dam X‐Section
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80 Original Rockfill Dam X‐Section
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81 Panel 72 Erosion
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82 Taum Sauk Forensic Investigation
• Field Investigations – Visua l Observat ions –Geologic Mapping • Breach Area •Breach Channel –Record Search – Test Borings & Sampling – Laboratory Testing – InstrumentationClick Investigationto edit Master title style – Interviews (operators & mgmt)
83 Forensic Investigation
• Engineering Analyses – HdHydrau lic AliAnalysis (fl(overflow zones, velitlocity, impingement zone) – Rockfill Dike (seepage, piping & stability) – Concrete Facing (effect on µ) –Liner (effect on µ) – Parapet Wall (stability, structural) – Asphalt Liner (effect on µ)
–Grout CurtainClick (effect to edit onMaster µ) title style – Filters (ff(effect on µ)
84 Rockfill Dike Stability ‐ Sliding
Water Pressure Resisting Click to edit Master title style Sliding Weight of Water W Estimated Normal Pore Force Pressure at Overtoppin 85 g Taum Sauk Re‐build Data
• Same Footprint • No change in capacity or generation • 110 to 140 ft high • ~ 6800 ft long ‐ 9 monoliths @ ~800 ft • RCC with processed “old rockfill” dam
• RCC – 2.8 millionClick to edit CY Master + 0.5 title million style CVC • Symmetrical w Concrete Face • Overflow Release Structure
• Highly redundant Instrumentation86 Rock Foundation Preparation
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87 Foundation Preparation
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88 Upstream View of the Fracture Zone Cleaning and Mapping in Progress
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89 Overflow Release Structure
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90 Taum Sauk on April 1, 2010
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91 Keys to a Forensic Investigation
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92 Keys to a Forensic Investigation
• Investigation Work Plan – Plan for Litiga tion from the biibeginning • Civil or Civil & Criminal • Expect Opposing Experts – Litera ture ShSearch – Interviews – Review of Existing Calculations & Design Basis – Field Investigations – Laboratory Testing – “New” AnalysisClick to edit Master title style – Report Preparation
93 Keys to a Forensic Investigation
• Have a well defined engagement letter • Avoid emails!! • Avoid derogatory remarks & comments • Keep consistent & accurate field logs • Keep confidentiality • Use NDA’s with Subcontractors • Treat drafts &Click preliminary to edit Master title documents style consistent with standard corporate policy • Implement a robust QA/QC Program • Be open minded!! 94 Keys to a Forensic Investigation
• Public Domain Literature Search – Professional Literature – News Accounts & Photos/Videos • Private File Search – STID’ s & PFMA’ s – Permit Applications – Inspection ClickReports to edit Master title style – Instrumentation Reports – CttiConstruction RRteports & Phot os
95 Keys to a Forensic Investigation
• Field Investigations (drilling, geophysics, etc) – Implement a Field Work Plan – Implement a HSEP immediately – IlImplemen t a QA/QC Program – Use Calibrated Equipment with traceable records • SPT Energy • Shelby Tube & Split Barrel Dimensions • Pressure gages, flow meters, DRM Systems Click to edit Master title style – Use SSlample MMifanifest PPlrotocols – Watch the field records carefully!!!! – Use NDA’s with subcontractors
96 Keys to a Forensic Investigation
• Laboratory Testing – Implement a Laboratory Testing Plan – Implement a Q/QQA/QC Program – Use Calibrated Equipment with traceable records – Use defendable Standards (ASTM, C of E, etc) – Use SampleClick Manifest to edit Master Protocols title style – Watch the lab records carefully!!!! – Should Field Logs be adjusted based on lab tests? 97 Thank you for your time!
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