2006 HURRICANE KATRINA, WHY THE LEVEES FAILED, IPET TASK IN THANE

This unique electronic book on CD-ROM has the vital report of the Interagency Performance Evaluation Task Force (IPET) on why the levees failed in New Orleans during Hurricane Katrina in August 2005. The task force, headed by the U.S. Army Corps of Engineers, conducted a performance evaluation of the New Orleans and Southeast Louisiana Hurricane Protection System. Overarching Findings from the overview of the report: "The System did not perform as a system: the hurricane protection in New Orleans and Southeast Louisiana was a system in name only. Flood protection systems are an example of a series system—if a single levee or floodwall fails, the entire area is impacted. It is important that all components have a common capability based on the character of the hazard they face. Such systems also need redundancy, an ability for a second tier of protection to help compensate for the failure of the first tier. Pumping may be the sole example of some form of redundancy; however, the pumping stations are not designed to operate in major hurricane conditions. The system’s performance was compromised by the incompleteness of the system, the inconsistency in levels of protection, and the lack of redundancy. Incomplete sections of the system resulted in sections with lower protective elevations or transitions between types and levels of protection that were weak spots. Inconsistent levels of protection were caused by differences in the quality of materials used in levees, differences in the conservativeness of floodwall designs, and variations in structure protective elevations due to subsidence and construction below the design intent due to error in interpretation of datums. The presence of closure gates such as those for the CSX railroad that must function as a part of the system, but are separately controlled, add to the inherent risk in the system. Redundancy was simply not included. Continuity of pumping could have significantly reduced at least the duration of flooding and in some areas the extent. Armoring the back sides and crests of levees and the protected side of floodwalls would have added significant redundancy and reduced breaching. Surge gates at the mouths of the outfall canals are an excellent example of providing redundancy. The combination of the surge protection for the canals and resilient levee-floodwall systems will dramatically reduce risk in Orleans East Bank. The storm exceeded design criteria, but the performance was less than the design intent: sections of the hurricane protection system were in many ways overwhelmed by the conditions created by Hurricane Katrina. This is particularly true for the sections of the Gulf Intracoastal Waterway (GIWW) along New Orleans East, and the levees in St. Bernard and Plaquemine Parishes where the combination of record high surge and long period waves exceeded the design conditions and devastated the levees."