There are five major federally authorized projects comprised of more than 350 miles of levees, floodwalls, and other flood control structures across six parishes that provide hurricane protection in southeastern Louisiana. While construction of hurricane protection projects in southeastern Louisiana began almost 60 years ago, construction of three major projects began about 40 years ago in the 1960s. Segments of those were still incomplete when Hurricane Katrina struck the area in late August 2005. The projects were designed to provide protection from hurricanes with maximum wind speeds of 87 to 115 miles per hour (115 miles per hour being roughly equivalent to a Category 3 hurricane). Hurricane Katrina made landfall with wind speeds equivalent to a Category 3 hurricane, or winds up to 127 miles per hour, and record high storm surge. To determine the extent of the damage to levees and floodwalls caused by Hurricane Katrina, the Corps contracted for an initial assessment in September 2005 and a second assessment in April 2006. Both assessments were based on visual inspections of the levees and floodwalls. For the first assessment, engineers walked the levees and floodwalls in Orleans, Plaquemines and St. Bernard parishes and looked for damage. The second assessment reexamined only those sections that were initially reported to be undamaged. The first assessment found 169 miles of damaged levees and floodwalls of which 128 miles were moderately damaged and 41 were severely damaged or destroyed. Most of the damage was found in Plaquemines Parish where 150 miles of levees and floodwalls were damaged. The second assessment of those sections initially found to be undamaged found additional cracks in the levees, soil erosion near floodwalls, and levee heights that had settled below their design elevation. Subsequently, the Corps and the contractors conducted sampling and other tests to determine the extent of the damage, but this was only done where exterior damage—such as cracks, depressions, or seepage—was observed. Both assessments documented obvious external damage but did not indicate whether other structures without visible damage—but similar in design and composition to damaged levees and floodwalls—were, in fact, damaged or weakened. In its May 2006 draft final report, an independent team sponsored by the National Science Foundation reviewed the failures of the hurricane protection projects and concluded that the pervasiveness of problems and failures calls into question the integrity and reliability of other sections of flood protection projects that did not fail during Hurricane Katrina. In its June 2006 draft final report, the Interagency Performance Evaluation Task Force—a team of 150 experts from the Corps and about 50 federal, state, international, academic, and industrial organizations—found that repaired sections of levees and floodwalls were likely the strongest parts of the system until remaining sections could be similarly upgraded and completed. The task force report concluded that since there are many areas where protection levels are only the same as before Hurricane Katrina, the New Orleans metropolitan area remained vulnerable to storm surge and wave conditions equivalent to or greater than Hurricane Katrina. The most severely damaged portions of the hurricane protection projects in the area were found in the three parishes of Orleans, Plaquemines, and St. Bernard. Within these three parishes, there are approximately 243 miles of earthen levees and 26 miles of floodwalls. The 26 miles of floodwalls comprised 19 miles of I-walls and 7 miles of T-walls. I-walls are vertical concrete barriers anchored to levees by steel sheet pile driven vertically into the levees. T-walls are vertical concrete barriers with a horizontal concrete base anchored by multiple steel beams driven diagonally into the levees and are stronger than I-walls (see fig. 1). Corps officials told us that T- or L-walls will be constructed to replace floodwalls that were destroyed and need to be replaced. Section 5 of the Flood Control Act of 1941, as amended, commonly referred to as Public Law 84-99, authorizes the Corps to conduct emergency operations and rehabilitation activities when levees fail or are damaged during storms. Under the implementing regulations for Public Law 84-99, after a storm, the Corps may repair and restore federally authorized flood control projects and hurricane protection structures, or nonfederal flood control projects that were inspected and found to have met federal standards for construction and maintenance prior to the flood event. Assistance for the rehabilitation of hurricane protection structures is limited to repair or restoration to the prestorm condition and level of protection (e.g., the prestorm elevation/height of levees, allowing for normal settlement). Under Corps policy, damage to federally constructed levees that have been completed and officially turned over to a nonfederal sponsor are to be repaired with 100 percent of the cost borne by the federal government and damage to nonfederally constructed levees are to be repaired with 80 percent of the cost borne by the federal government and 20 percent by the local sponsor or government. However, in September 2005, the Corps noted that Hurricane Katrina had caused unprecedented damage and loss of infrastructure in the Gulf Coast region. According to the Corps, damage to the region eroded the tax base to such an extent that local sponsors would have great difficulty funding their share of rebuilding expenses. In response, the Corps requested a one-time waiver from the Assistant Secretary of the Army for Civil Works from the policy requiring local sponsors to fund 20 percent of the cost of rehabilitating nonfederal flood and hurricane protection projects. For federally authorized projects that were under construction when Hurricane Katrina made landfall, the Corps also requested a waiver from the policy requirement that local sponsors fund a share of the repair cost. In October 2005, the Assistant Secretary of the Army for Civil Works approved both requests. In the December 2005 emergency supplemental, Congress appropriated funding to the Corps to repair levees and flood control structures damaged by Hurricane Katrina to the level of protection for which they were designed, at full federal expense. Most earthen levees are constructed with a mixture of clay and sand. The most commonly used method is to build an earthen embankment sloped on both sides and rising to a flat crown (see fig. 2). Depending on local conditions and the availability of suitable materials, levees can be built in one or more stages. The number of stages is generally dependent on the ability of the local soil to provide an adequate base, and not sink under the weight of levees, and to compact and provide suitable strength. When appropriate conditions exist, levees can be built in a single stage. In other cases, levees may need to be built in stages (also called lifts) that allow for subsidence of the foundation soil or settlement of the fill material. Between stages the levees are allowed to settle for up to 5 years. Because the soil in southeastern Louisiana has a tendency of settling, historically most levees built in the New Orleans area were required to be built in three to four stages, and construction took 15 to 20 years. Because of the urgency of the repairs that the Corps made after Hurricane Katrina, earthen levees in the New Orleans area had to be rebuilt in only several months. To do this, the Corps relied on mechanical compaction by heavy construction equipment to compensate for the normal settlement that would occur over time. Building levees quickly can pose risks, however, as was witnessed on May 30, 2006, when a 400-foot section of a reconstructed levee in Plaquemines Parish slipped 3 to 4 feet under its own weight. Corps officials said the underlying soil was weaker than previous tests had indicated and was unable to support the weight of the newly constructed levee. To provide interim protection, the Corps constructed a small earthen berm on top of the levee to return it to approved design height by June 7, 2006. By June 1, 2006, the Corps planned to complete repairs to 169 miles of southeastern Louisiana hurricane protection projects to prestorm conditions—that is, to repair most levees and floodwalls to the condition they were in before Hurricane Katrina. For 128 miles of levees with minor or moderate damage, the Corps planned to repair or fill scour (erosion) and holes. For 41 miles of levees and floodwalls with major damage, or that were completely destroyed, the Corps planned to rebuild these damaged sections entirely, including rebuilding to the original design grade, plus an allowance for settlement. The Corps only planned to repair hurricane-damaged levees and structures and did not plan to repair or replace any existing levees or floodwalls unless exterior damage was observed. The Corps awarded 59 contracts to repair damage in three sections of the city of New Orleans (Orleans East Bank, New Orleans East and the Inner Harbor Navigation Canal, commonly called the Industrial Canal) and the parishes of Plaquemines and St. Bernard. The following sections briefly describe the location and damage caused by Hurricane Katrina for these five areas and the number of contracts the Corps awarded for completing the repairs. Orleans East Bank is located south of Lake Pontchartrain, from the 17th Street Canal to the Inner Harbor Navigation Canal, and along the western bank of the Inner Harbor Navigation Canal to the Mississippi River. About 19 miles of levees and floodwalls are along the Orleans Lakefront, the Inner Harbor Navigation Canal and three drainage canals—17th Street, Orleans Avenue, and London Avenue—which drain rainwater from New Orleans into Lake Pontchartrain (see fig. 3). A total of about one mile of levees and floodwalls were damaged along the 17th Street Canal and two sides of the London Avenue Canal. There was also intermittent minor erosion, and all 13 of the area’s pump stations were damaged. The Corps constructed interim sheet pile walls at the breach sites along the drainage canals and contracted for the construction of permanent T-walls at each of the breach sites.