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Upcoming Changes for EM 1110-2-1913 D i C i d E l i fDesign, Construction, and Evaluation of LeveesScott E. Shewbridge, PhD, PE, GENational Technical Specialist – Risk & Geotechnical Engineeringp g gRisk Management Center, DenverMichael Navin, PhD, PE US Army Corps of Engineers, St. Louis DistrictNeil Schwanz, PE ,US Army Corps of Engineers, St. Paul DistrictNoah Vroman, PE US Army Corps of Engineers, MVD Dam and Levee Safety Production Center, Vicksburgy g
USSD Fall 2015 Levee Workshop
November 3, 2015
ObjectiveObjective
To provide an overview of the updatesTo provide an overview of the updates being proposed for EM 1110-2-1913 Design Construction and Evaluation ofDesign, Construction, and Evaluation of Levees
2/81
ContentsContents
Introduction and overview of someIntroduction and overview of some regional design differences Review of Chapters Review of Chapters Questions and Discussion
3/81
Complaint About Old EMComplaint About Old EM
“It’s great if you are from the MississippiIt s great if you are from the Mississippi Rivers and Tributaries Project, but th ’ thi b t th t f lthere’s nothing about the types of levee designs we do here in _____________.”
4/81
Primary ObjectivesPrimary ObjectivesTo update the USACE EM for Design,
Construction and Evaluation of Levees►Compile information on regional design►Compile information on regional design
approaches and performance expectations including operations, maintenance, flood-fighting efforts and associated documentation
►Use risk-based potential failure modes to establish design objectives and approaches
►Assess adequacy of traditional design with risk l i th danalysis methods
5/81
EM Revision TeamEM Revision TeamEM Revision PDT
1 Scott Shewbridge RMC2 Noah Vroman MVD - Mississippi Valley Division MVK - Vicksburg3 Ken Klaus Emeritus ERDC3 Ken Klaus - Emeritus ERDC4 Mike Navin MVD - Mississippi Valley Division MVS - St. Louis5 Neil Schwanz MVD - Mississippi Valley Division MVP - St. Paul6 Tom Brandon – Adjunct to ERDC Virginia Tech
Regional Representatives “EM Collaborators”Regional Levee Design PFMA Session / ATR
EM Collaborators / Regional Levee Design Contributors1 Pat Conroy Geotech MVD - Mississippi Valley Division - St. Louis2 Doug Chitwood, PE GE Geotech SPD - South Pacific Division - Los Angeles3 Glen M Bellew, PE Geotech NWD - Northwestern Division - Kansas City4 Derek Morely PE, Geotech SPD - South Pacific Division - Sacramento4 Derek Morely PE, Geotech SPD South Pacific Division Sacramento5 Christina Neutz Geotech LRD - Great Lakes and Ohio River Division - Louisville6 Tom Mack Chief Geotech MVD - Mississippi Valley Division - Rock Island7 Mark Woodward Geotech MVD - Mississippi Valley Division - New Orleans8 James Snyder Geotech NAD - North Atlantic Division - Baltimore
6/81
Example Case HistoriesMississippi Valley Division – New Orleans
7/81
Marchand Levee Failure 1983
8/81
Flow Slides in SandFlow Slides in Sand
9/81
ACM provides the best level of protection along the rivers in the ACM provides the best level of protection along the rivers in the New Orleans District’s jurisdiction due to the depth of water and New Orleans District’s jurisdiction due to the depth of water and construction issues with using other materials in those depths. construction issues with using other materials in those depths.
10/81
Hurricane Protection – StabilityWith Reinforcement FabricWith Reinforcement Fabric
11/81
Geotextile Installation
12/81
Example Case HistoriesMississippi Valley Division – Rock Island
13/81
Design of Sand LeveesDesign of Sand LeveesDesign Philosophy
• The through seepage control must prevent the slope failure and excessive erosion of the landside slope.
• The under seepage design criteria must control the hydraulic gradients landward of the levee to prevent piping and excessive uplift pressures on the landsidepiping and excessive uplift pressures on the landside impervious stratum.
• Stability usually not an issueStability usually not an issue
14/81
Drury and Iowa River/Flint Creek Test S ti 1962 d 1964Sections 1962 and 1964
15/81
1616/81
Results of Test Section: Typical Sand Levee Cross Section
4:1 Riverside slope 10 foot crown 5:1 Land side slope
► Steeper slopes resulted in erosion due to through-seepageseepage.
10 h base width (The width at the base of the levee is 10 time the height of the levee.)► On heights greater than 10 feet a berm is required
• 3 feet thick usually 20 feet wide. • Design based on seepage and stability analysis (EM 1913)g p g y y ( 9 3)
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Example Case HistoriesNorthwestern Division – Kansas City
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2011Missouri River Performance History
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Example Case HistoriesNorth Atlantic Division – Baltimore
21/81
Typical Levee Section( i h MSE W ll)(with MSE Wall)
NAB – Scranton22/81
Example Case HistoriesSouth Pacific Division – Los Angeles
23/81
Site GeologySite Geology
24/81
Levee Embankment – Soil CementLevee Embankment Soil Cement
Soil Cement
Original Levee
ChannelTypical Soil Cement Grade
ypEmbankment Section
Soil Cement Original Levee
Soil Cement Original Levee
ChannelGrade
Landside Slope
Grade
25/81
Example Case HistoriesSouth Pacific Division – Sacramento
26/81
Design Concept: Deep CutoffDesign Concept: Deep Cutoff Degrade ½ levee heightg g Extend cutoff wall down
into low perm layer Regrade with clay corelevee
blanket
high perm layer
low permlow perm layer
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Example Case HistoriespGood Coverage for Entire Country
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EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
29/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
Significant Updates30/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
31/81
Design Water Surface ElevationDesign Water Surface Elevation The top of barrier associated with the Design Water Surface
Elevation plus superiority plus over-wash height (or wave runupoverbuild) is termed the project (final) levee grade. Where superiority and over-wash height are zero, the final levee grade equals the DWSE.
All standard geotechnical analyses (such as seepage, stability, and erosion) shall use the DWSE with the standard design requirements (such as effective stress/vertical gradient factor of safety, slope t bilit f t f f t t )stability factor of safety, etc.).
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StandardsStandards
“in this engineering manual (EM)in this engineering manual (EM), traditional design standards remain largely unchanged from previous editions but aunchanged from previous editions, but a risk-informed process for evaluating required levee reliability for requestingrequired levee reliability for requesting variances from the standards when reliability is either too high (too expensive)reliability is either too high (too expensive) or too low (too much risk).”
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Old Levee, Updated Standards?Old Levee, Updated Standards?
For existing levees, all future evaluations will be based g ,on the same above risk-informed reliability evaluation process regardless of the method for how it was designed in the past If the reliability of the existing leveedesigned in the past. If the reliability of the existing levee is too low for the current estimated consequences, then the levee becomes a candidate for reevaluation within
S C fthe USACE levee safety program routine processes, leading to further risk assessments and potential follow-on feasibility studies, congressional funding y , g gauthorizations, and improvement design and construction.
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EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
35/81
ASTM Standard TestsASTM Standard Tests
36/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
37/81
Geomorphology and GeophysicsGeomorphology and Geophysics
38/81
TM 3-424 Mississippi River
Martis Creek Sierra Glacial
Texas Coast Littoral
39/81
Standardized Material Graphics and ColorsSta da d ed ate a G ap cs a d Co o s
40/81
Guidance On Interpretation Process d P t l f S ti D tand Portrayal of Supporting Data
41/81
Interpreted and Analyzed SectionsInterpreted and Analyzed Sections
42/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
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Analysis MethodsAnalysis Methods
Focus on modern FEM computer methodsFocus on modern FEM computer methods while still considering “Blanket Theory”
44/81
Effective Stress Heave/Uplift Design Criteriaect e St ess ea e/Up t es g C te a
45/81
Seepage Berm DesignSeepage Berm DesignFS = 1.6DWSE FS = 1.0
Berm Crown
BermTop Stratum
LeveeRiverChannel
Pervious Substratum
p
Levee Toe
Berm Width
Berm Toe
Use existing factor of safety criteria for critical vertical gradient / effective stress factor of safety for uplift at end of berms.f f S 1 6 f If end of berm FoS is less than 1.6, then also assess likelihood of
progression of backwards erosion
46/81
Backwards Erosion / Piping FailureC R ti d/ C iti l H i t l G di tCreep Ratios and/or Critical Horizontal Gradients
47/81
Example With Vertical and H i t l G di t C id ti
Landside BermMeets USACE Vertical Gradient/
Seepage Path Length No BermCreep Ratio Too Low
Horizontal Gradient ConsiderationsMeets USACE Vertical Gradient/Effective Stress Design Criteria
& Increases Seepage Path Length
Creep Ratio Too Low
Seepage Path Length With BermCreep Ratio Sufficient (?)
Clay Blanket Thin Blanket Does Not MeetClay Blanket Thin Blanket Does Not MeetUSACE Vertical Gradient/
Effective Stress Design CriteriaVertical Boils Expected Here
Sand Aquifer
48/81
Failure Modes & Event TreesFailure Modes & Event TreesFlood Fighting Impacts
Traditional Creep Ratio or Modern Horizontal Gradient Computations
49/81Traditional Vertical Gradient / Effective Stress Computations
Filtered Toe Drain (aka Trench) DesignFiltered Toe Drain (aka Trench) Design
50/81
Relief WellsRelief Wells
51/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
52/81
“Critical State” Soil Behavior Framework
53/81
Summary of Types of Clays, Relative Strengths, Loading Conditions Conventional Names and Conditions ControlledConditions, Conventional Names and Conditions Controlled
54/81
Selection of StrengthsSelection of StrengthsTime for 99% DrainageTime for 99% Drainage
dense“strength”
NC “ t th”
Undrained Strengths Drained Strengths
dense and NC “strength”NC “strength”
g g
55/81
56/81
aka “Rapid Flood Loading” of Soft Materials57/81
For more information see 2013 ASDSO C f P di2013 ASDSO Conference Proceedings
58/81
Levee Seismic RiskP t S i i W i / R Ti S iPost Seismic Warning / Response Time Scenarios
Earthquake
Earthquake
WSELeveed Area
Elevation
Earthquake
amag
e
fe /
Hig
h D
amag
e
ife
Red
uced
Da
Hig
h Lo
ss o
f Lif
No
Loss
of L
TiLong None
(evacuations and repairs)
Time
59/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
60/81
Analytical FrameworkAnalytical Framework
61/81
Typical Analysis ParametersTypical Analysis Parameters
62/81
Design of Overtopping - Resiliency Measureses g o O e topp g es e cy easu es
63/81
Design of Overtopping - Resiliency Measureses g o O e topp g es e cy easu es
64/81
Transition Area ArmoringTransition Area Armoring
65/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-
Based Decisions During Design and Construction
Chapter 3. Field Investigations for Levees Chapter 4 Laboratory Testing for Levees
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 4. Laboratory Testing for Levees
Chapter 5. Borrow Areas Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control
Ch t 8 Sl D i
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 8. Slope Design Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 12. Levee Construction Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
66/81
USBR / USACE “Best Practices”USBR / USACE Best Practices
67/81
Failure Modes & Event TreesFailure Modes & Event TreesFlood Fighting Impacts
Traditional Creep Ratio or Modern Horizontal Gradient Computations
Traditional Vertical Gradient / Effective Stress Computations68/81
Risk-Informed Design ProgressionRisk Informed Design Progression1
TRRL0.1
0.01 Existing ConditionsFailu
re
Existing Conditions
Low Population Levee High Population Levee
TRRL
0 0
1E-3
Existing Conditions
babi
lity
of F
Minimum Berm
Existing Conditions
Minimum Berm
Mi i B1E-4
1E-5
ualiz
ed P
rob
Higher Standard Berm
Higher Standard BermFl d Fi hti
Minimum Berm + Flood Fighting
1E-6
1E 7
Ann
u + Flood FightingHigher Standard Berm+ Flood Fighting+ Improved Emergency Evacuation
Life Loss10.10.01 10 100 1,000 1E4 1E5
1E-7
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How “Reliable” Does the Levee Need to Be For Prior-to-O t i F il M d Wh O t i C t l ?Overtopping Failure Modes When Overtopping Controls?
1TRRL
0.1
0.01
TRRL
Existing ConditionsFailu
re
Existing Conditions
Low Population Levee High Population Levee0 0
1E-3
Existing Conditions
babi
lity
of F
Minimum Berm
Existing Conditions
Minimum Berm
Mi i B
Overtopping1/300 years
1E-4
1E-5
ualiz
ed P
rob
Higher Standard Berm
Higher Standard BermFl d Fi hti
Minimum Berm + Flood Fighting
How Far?
1E-6
1E 7
Ann
u + Flood FightingHigher Standard Berm+ Flood Fighting+ Improved Emergency Evacuation
Life Loss10.10.01 10 100 1,000 1E4 1E5
1E-7
70/81
Taylor Series Approximate Solution – First Order Second MomentCan be used with virtually any limit state analysis.y y y
Only Models Aleatory•Vary each factor by +/1 sigma,L k t i ti i•Look at variation in response
function,•Use that as estimate of variance of response function
•Compare distance of “Limit State” to “Expected” value and based on variance estimated above, calculate percentage of area under lognormal curve for values greater
71
lognormal curve for values greater than the limit value.
Epistemic Uncertainty“U k U k ”“Unknown-Unknowns”
For geotechnical engineering, epistemic uncertainty g g g, p y(knowledge uncertainty) in many situations is more important than aleatory (natural variability), because it often cannot be estimated directly and can haveoften cannot be estimated directly and can have dramatic impact.
For geotechnical failure modes, both for design and reliability assessments, the epistemic uncertainty “unknown-unknown” challenge is common and well-known to the profession and has been addressedknown to the profession and has been addressed through a classic inductive-reasoning approach referred to as the Terzaghi and Peck “Observational Method” (P k 1969)(Peck 1969).
Epistemic Uncertainty Risk Mitigation and L S f t P N R ti A ti itiLevee Safety Program Non-Routine Activities
Recognizing that it is not possible to eliminate all “unknown-unknowns” on levee systems, per current and past USACE practice, performance monitoring and flood fighting will remain important risk reduction measures to reduce epistemic uncertainty over time. All f il d t t l ill i l d t d fAll failure mode event tree analyses will include event nodes for Unsuccessful Detection and Unsuccessful Intervention.
As a part of the proposed levee safety program (Draft EC 1110-2-6072, USACE 2014) if f f l i d d t dUSACE, 2014), if performance of a levee is deemed too poor and flood fighting activities too demanding and unreliable, a risk-informed process will be initiated to evaluate the needs for additional actions If risk is high enough a variety of structural and nonactions. If risk is high enough, a variety of structural and non-structural actions to increase levee reliability (i.e., change the fragility curves) and/or decrease potential consequences will be consideredconsidered.
Failure Modes & Event TreesFailure Modes & Event Trees
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EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
75/81
Explicit Description of Expected “Flood Fighting”p p p g g
76/81
Example Flood Fighting Evaluation“More than expected and, but for flood fighting, levee would have failed”p g g
Ensley Berm, Memphis 2011
Levee did not fail, but internal erosion pipes projecting towards the river found in 2012.
77/81
Example Flood Fighting Evaluation “Flood fighting occurred but levee failed”g g
L-575 Breach, NW Atchison County Levee District, Hamburg Iowa 2011
Possibly due to defects in riverside cap - fourth pipe formed and breached on June 13, 2011.
78/81
EM Chapters and AppendicesEM Chapters and Appendices Chapter 1. Introduction
Ch t 2 L F il M d d Ri k B d Appendix A. References Appendix B Typical Regional Designs and Typical Chapter 2. Levee Failure Modes and Risk-Based
Decisions During Design and Construction Chapter 3. Field Investigations for Levees Chapter 4. Laboratory Testing for Levees
Ch t 5 B A
Appendix B. Typical Regional Designs and Typical Design Documentation Report Contents
Appendix C. An Overview of Probabilistic Analysis for Geotechnical Engineering Problems –
Methods to Assess of Levee ReliabilityA di D S b f I t t ti G hi Chapter 5. Borrow Areas
Chapter 6. Subsurface Interpretation Chapter 7. Seepage Evaluation and Control Chapter 8. Slope Design
Appendix D. Subsurface Interpretation Graphics Appendix E. Levee Seepage Analysis using Blanket
Theory and Finite Element Methods Appendix F. Analysis and Design of Seepage
Berms Chapter 9. Settlement Chapter 10. Erosion Control Chapter 11. Design and Bid Packages Chapter 12. Levee Construction
Appendix G. Toe Drain Analysis and Design Appendix H. Finite Element Method Seepage
Analysis for Relief Wells Appendix I. Soil Behavior for Slope Stability Appendix J. Geotextile Reinforced Embankment on
Chapter 13. Special Features Chapter 14. Development of Levee Operations
and Maintenance Manual
Appendix J. Geotextile Reinforced Embankment on Soft Foundation
Appendix K. Use of soil cement for levee protection Appendix L. Emergency flood protection Appendix M. Notation
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ScheduleSchedule
Independent External Peer Review (IEPR)Independent External Peer Review (IEPR)►Contract in Negotiation►Anticipated Completion December 2015►Anticipated Completion December 2015
More Review? Publication FY2016 Q3 or Q4
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Questions / DiscussionQuestions / Discussion
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