I read "Breach of Faith" by Jed Horne, and I checked out the History Channel's "Modern Marvels: Engineer Disasters: New Orleans" episode from the library and watched it. Between these two sources there are conflicting reports of the strength of the storm that hit the Louisiana and Mississippi Gulf Coast and conflicting reports of how the levees failed.

In "Modern Marvels", they report Hurricane Katrina was a category 4 hurricane when it made landfall. "Breach of Faith" reports it was a category 3 hurricane. The Congressional Research Report for the People also reports Hurricane Katrina was a category 3 storm.

Why is this an issue? If the storm was a category 4 hurricane, the Army Corps of Engineers has an excuse for why the levees failed. They were only built to withstand a category 3 hurricane. If Katrina was a category 4 storm, it could provide a sufficient defense in any law suits against the Army Corps. But if Katrina was a category 3 hurricane when it made landfall, the Army Corps would be responsible for the disaster for levee design flaws or construction mistakes or both.

However, suing the federal government or any of its agencies is very difficult because of all the immunity built into the federal system, especially the Flood Control Act that ordered the Army Corps to construct the levees and other flood control structures. The FCA has very broad immunity even if the Army Corps is found negligent. See the link to the CRS Report above. There is a detailed report of the federal liability.

Both sources agree that the design of the levee flood walls was flawed, and the flaws were going to cause a disaster at some point, no matter how weak or strong the storm. The design called for the sheet pilings to be sunk anywhere from 15 to 25 feet below sea level. It's well known by civil engineers in the area that 25 feet isn't anywhere near far enough down to stabilize the levees during a hurricane and storm surge. The soil at 25 feet below sea level is full of silt and is very soft with a high water content. It easily absorbs more water and when it becomes saturated, the soil turns to a very soft mud (like Jell-O) that gives way with very little pressure.

"Breach of Faith" reports that research shows no levees were over-topped. "Modern Marvels" reports that the Industrial Canal levee was over-topped, which caused it's failure and the flooding of the Ninth Ward. Failure of a levee by over-topping occurs because the water running over the top scours the dry side's soil and rock structure away until it's deep enough to allow the levee walls to turn sideways, allowing water through to flood the area.

The scientist interviewed for the levee failure investigation clearly showed evidence that the Industrial Canal levee was over-topped. You can clearly see how the flood walls had turned sideways. It failed in an entirely different way than the London Avenue and 17th Street Canal levees.

"Modern Marvels" also reports that the London Avenue and 17th Street Canals were not over-topped, but failed because the pilings weren't driven far enough below sea level to stabilize those flood walls. They tipped over into the water when the pilings below them gave way.

The good news is the sections of levee that failed are being rebuilt with pilings driven 75 feet below sea level. However, there are still miles of levees that don't have pilings that deep. Since those sections didn't fail, they may not be rebuilt to have pilings driven down to 75 feet below sea level. What will happen if another storm hits New Orleans and those sections fail because the weaker sections were repaired and are now the strongest sections of levee? Only time will tell if the entire flood wall system will be strengthened before another disaster occurs.

Those interviewed for the "Modern Marvels" episode gave factual and well researched accounts of the engineering failures that occurred. But it was clear that those interviewed stuck strictly to the scientific and engineering facts. No opinions were given other than expert opinions based on research about the actual engineering failures that occurred. The only facts about the suffering of the people left in the city were that there were about 25,000 people without enough food or water, many were rescued off their rooftops, and most of them ended up at the Superdome and New Orleans Arena before they were evacuated. They also gave the death toll, that about 1,300 people died in New Orleans as a result of the disaster.

I checked out the History Channel's "Modern Marvels: Engineer Disasters: New Orleans" episode from the library and watched it. I discussed the levee failures in the article above.

Other engineering disasters that occurred in New Orleans during Hurricane Katrina were the failure of the pumping stations, the Superdome's roof, and the failure of the I-10 (east) Causeway bridge across Lake Pontachartrain.

The pumping stations have pumps in them that were originally designed and built in 1913. They are electric pumps, so when they get wet, they short out or have to be turned off and powered down to prevent damage to the pumps and electrocuting the operators. One new pumping station has newer pumps that have a water-tight casing and ventilation system around them to prevent water from entering them. A few of the old stations have a pump with a casing around it. The new pumping station is also built so the pumps are above sea level. Many of the older stations are built so the pumps are nearer ground level, which is below sea level. When the city flooded, and the water level reached the electric pumps, the pumping stations had to be powered down and the operators had to swim for their lives or drown.

Once water flows into the city of New Orleans, it doesn't come out unless it is pumped out. The city is leveed on all sides and resembles a bowl. That bowl is anywhere from a little above sea level in the French Quarter to about 15 feet below sea level at its lowest points. With 80% of the city flooded and the pumping stations down, the water was there to stay until the pumps could be dried and brought back online.

If it weren't for the encased pumps, the city would have taken much longer to empty. The encased pumps were dry and could be energized and restarted as soon as the levee breaches were temporarily sealed. The Army Corps also brought in portable pumping equipment to help speed the process. But it took two weeks to empty the city and repair the rest of the pumps.

Nearly all of the pumps used are no longer manufactured, so the parts needed to repair them have to be fabricated by hand. The old pumps also had to be completely dry before they could be used again. That takes time, so bringing the old, damaged pumps back up was slowed by the lack of standard parts to rapidly repair them, and the wet conditions all around them.

The Superdome roof was supposed to withstand category 5 hurricane force winds. It clearly did not. Wind tore off a section of the roof's skin when it tore off one of the vents. This allowed the wind to get underneath more of the skin and removed most of it. Once the styrofoam layer under the skin was exposed, enough of it came off to allow water to flow into the Superdome, making miserable conditions inside it even more unbearable. When the roof was repaired, new engineering methods were used to make the outer layer of the dome much stronger, and the second layer much more water tight. With the new design, a failure in one part of the skin should not cause failure in the rest of the skin or it's next layer.

The Causeway failed because rising water trapped air under the concrete roadway and the pressure lifted several sections of roadway off its pilings and knocked them over like dominoes. This failure hindered access to the city from the east. The new road sections have holes to prevent pressure from building under the roadway sections. It can flood, but it shouldn't fail. When flood waters recede the road will be intact and accessible.

Those interviewed for the "Modern Marvels" episode gave factual and well researched reports of the engineering failures that occurred. But it was clear that those interviewed stuck strictly to the facts. Only expert opinions based on research about the actual engineering failures were given. The only facts about the suffering of the people left in the city were that they numbered about 25,000, and there wasn't enough food or water. Many were rescued off their rooftops, and most of them ended up at the Superdome and New Orleans Arena before they were evacuated. They also gave the death toll, that about 1,300 people died in New Orleans as a result of the disaster. There was no discussion of the amount of time it took to evacuate those remaining people, nor the hell they lived through or died in.

The "Modern Marvels" account focuses on the fact that the Causeway was destroyed, hindering rescue efforts. They completely failed to mention that the Causeway isn't the only major road into New Orleans. There are three other major roads that could have been used: Airline Highway, The Bonnet Carre Spillway Bridge (I-10 west to and from Baton Rouge) and I-55, which runs north and south through eastern Louisiana and into Mississippi. There was also access from the west and its many smaller highways. The Causeway bridge being out was a factor in rescue efforts, but a much smaller one than the show suggested.

I can't fault "Modern Marvels" for it's lack of discussion about all the human suffering and what went wrong with the FEMA response because it is a one hour show on science, technology and engineering. It doesn't claim to give a sociological view of all the implications of the technology failures it reports. I do hope the History Channel and other documentary channels such as Discovery, Discovery Times and The Learning Channel will bring the social, economic and other human issues forward so America and the world can see how severely the people suffered and how botched the FEMA response was.

The disaster in New Orleans was not a natural disaster, though a hurricane set it off. The root causes of the disaster were the engineering failures of the structures that were supposed to protect the city and its people, and the human failures to completely evacuate the city. There are many other human-caused and natural factors that led to the disaster as well, such as subsidence, lack of proper funding for the Army Corps, and wetland and barrier island losses over the last 3 centuries because of man's tampering with nature. These are subjects for another article.

I hope the many of you out there who think the recovery should be complete and all this should be behind us will realize that isn't the case. The recovery is painstakingly slow. Many neighborhoods won't be rebuilt because the residents won't come back. There is a general question about how much of New Orleans should be rebuilt and inhabited. The levee and flood wall systems are still only strong enough to withstand a category 3 hurricane's storm surge. The pumping stations are still the same. More storms will enter the Gulf of Mexico and a category 4 or 5 hurricane will eventually strike New Orleans again.

The big question is what are we as a nation going to do to protect New Orleans from such a disaster in the future?