New Orleans

1
New Orleans Levee Failures

• Chalston Layacan
• Elizabeth Lenker
• Jamie Mellies

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Outline

• Background
• Hurricane Katrina
• Levee System
• Destruction
• Failures
• General Problems
• 4 Mechanisms of Failure
• Future
• Immediate Reconstruction
• Long Term Goals
• List of References

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Hurricane Katrina

• August 29, 2005
• One of the strongest storms ever to hit the US
  coast
• Hit Gulf of Mexico and shores of Louisiana,
  Mississippi, and Alabama
• Killed over 1,000 in Louisiana resulting in over
  27.7 billion in damage

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New Orleans Levee System

• What is a levee?
• A protective barrier built along the banks of any
  body of water to protect the neighboring land
  from being flooded
• Levees and floodwalls were built along canals,
  Lake Pontchartrain, and the Mississippi River to
  protect against flooding.

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Types of Levees

• Earthen
• A ridge of dirt along a body of water, equivalent
  to a bank
• I-Wall
• An earthen levee with linked steel pilings driven
  into the ground and a concrete wall above ground
• Stronger than an earthen levee

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Where the Levees Were Breached
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The Destruction

• Many of the levees and floodwalls collapsed or
  were overtopped by water, which allowed billions
  of gallons of water into New Orleans and flooded
  the city.
• Levees collapsed at approximately 50 locations.
• Out of 284 miles of levees and floodwalls, 169
  miles were damaged.
• If the levees and floodwalls had not failed, 2/3
  of the deaths would not have occurred.
• The catastrophic failure of New Orleans
  hurricane protection system represents one of the
  nations worst disasters ever.

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Poorly Designed Levees

• Levees were only designed to withstand a Standard
  Project Hurricane. (set in the 1950s)
• Levees were built on and made of soft,
  erosion-prone soils.
• Foundations were not sunk deep enough into the
  ground. At the 17th Street canal, the pilings
  were supposed to be 17 feet below the ground but
  were only 10 feet.
• Measurement problems and subsidence caused some
  levees to be built several feet lower than
  designed.

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Four Mechanisms of Levee Failure

1. Overtopped earthen levee
2. Overtopped I-wall levee
3. Sliding soil under I-wall levee
4. Water flowing through sand layer under I-wall
   levee

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Overtopped Earthen Levees

• All levees without I-walls were overtopped by the
  storm. The levee was completely washed away in
  some cases.
• Levees built with sand, silt, or by hydraulic
  fill were damaged the most.

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Obliterated Levee(along Mississippi River-Gulf
Outlet)
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Overtopped I-Wall Levees

• Water flowing over the levee eroded the earth on
  the protected sides of the levees.
• Water washed away the soil near the foundation of
  the I-wall, weakening the foundation.
• Water then pushed over the top of the levees
  causing a collapse.

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Overtopped I-Wall Levees
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Overtopped I-Wall Levee(Industrial Canal, East
Bank, South Breach)
WALL
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Industrial Canal, East Bank, South Breach(due to
I-wall levee overtopping)
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I-Wall Levees sliding soil

• In the design, the engineers underestimated the
  strength of the soil.
• They also did not account for the presence of a
  water-filled gap.

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17th Street Canal Failure (due to sliding soil)
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London Ave Canal North Breach(due to sliding
soil)
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Industrial Canal, East Bank, North Breach(due to
sliding soil)
21
I-Wall Levees water flowing through sand layer

• Engineers didnt account for the water seeping
  into the sand layer under the levee and coming up
  the other side.

22
London Ave Canal South Breach (caused by water
flowing through sand layer)
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Immediate Reconstruction

• Task Force Guardian
• U.S. Army Corps of Engineers project
• Floodwall repair and replacement
• Levee repair to a height of 15 ft
• Levee armoring reinforcing slopes with riprap
  or concrete to prevent erosion when the levee is
  overtopped

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Long term goals

• Task Force Hope
• U.S. Army Corps of Engineers project
• Ultimate goal integrated levee and floodwall
  system able to withstand category 5 storm
• Restoring wetlands, which will act as natural
  buffer
• Levee armoring
• Permanent gated structures for canals
• Channel control-floating flood control gates on
  the Mississippi River-Gulf outlet

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List of References

• Articles
• Keeping the Waters at Bay by Thomas Hayden U.S.
  News World Report Feb. 27, 2006
• Little Good News on Levees and Wetlands by
  Meghan Stromberg Planning Vol. 72, Issue 1Jan.
  2006
• Websites
• Katrinas Levee Failures Cleansing the Corps
  by Anthony Kendall Jan. 17, 2006
  http//www.anthonares.net/2006/01/katrinas-levee-f
  ailures-cleansing.html
• The New Orleans Hurricane Protection System
  What Went Wrong and Why a Report by the
  American Society of Civil Engineers Hurricane
  Katrina External Review Panel. http//www.asce.org
  /files/pdf/ERPreport.pdf
• Pictures
• www.fishindog.com/images/katrina1.jpg
• bbsnews.net/bbsn_photos/topics/hurricane_katrina/u
  scg_new_orleans_under_water20050829.jpg
• www.katrina-hurricane.biz/images/katrina-hurricane
  -pic3.jpg
• http//www.asce.org/files/pdf/ERPreport.pdf
• www.killedthat.com/wp-content/uploads/2007/08/hurr
  icane-katrina.jpg