Answers from Army Corps of Engineers on unwatering New Orleans

11:28 PM CDT on Tuesday, August 30, 2005

Q.1. How long will it take to get the water out of New Orleans?

A.1. We are unsure. A number of factors play into this. First, Lake Pontchartrain is at roughly 4.5 feet above sea level and falling. The city is at a lower elevation so water will continue to flow into it until it equalizes.

Once the breach on the 7th Street Canal is closed, Pump Station 6 can pump 10,000 cubic feet per second.

Once the breaches are closed and all of the pumps are running, the pumps can lower the water level ½ inch per hour or about a foot per day. We can get the water level to sea level in four and a half days. The ½ inch rate assumes the late is at normal levels. That would create pumping inefficiency, as could trash in drains and canals that feed into the pump stations.

That’s a “Best Case” scenario. We don’t know the conditions of all of the pumps. Fortunately most of the pump motors and controllers are at an elevation greater than 5 feet and we hope they weren’t submerged. There could be other unforeseen problems.

We assume the pumps have not been submerged since most pumps are at an elevation greater than five feet above sea level. Pumps are operated and maintained by the local sewage and drainage districts.

Q.2. Why did the levees fail?

A.2. What failed were actually floodwalls, not levees. This was caused by overtopping which caused scouring, or an eating away of the earthen support, which then basically undermined the wall.

These walls and levees were designed to withstand a fast moving category 3 hurricane. Katrina was a strong 4 at landfall, and conditions exceeded the design.

Q.3. Why only Category 3 protection?

A.3. That is what we were authorized to do.

Q.4. How many other areas do you need to get water out of?

A.4. There are at least five ringed levees (areas surrounded by levees) that need to be emptied. New Orleans and Jefferson; New Orleans to Venice (Hurricane Protection project - Port Sulfur to Venice, LA); Chalmette Loop (lower 9th ward of Orleans Parish and Urbanized part of St. Bernard Parrish ); and, Plaquemines Parish non-federal levees have also been overtopped.

Q.5. What will be done to unwater these areas?

A.5. The unwatering plan will be used in these areas as well. Crews and equipment will be mobilized to breach the levees at predetermined locations and allow for gravity drainage into Lake Bourgne or other surrounding water bodies.

For more information, contact the New Orleans District Public Affairs Office at the crisis action center (601) 631-5328. Please also visit the New Orleans District website (www.mvn.usace.army.mil) -- it's up once again.

 

Thanks Tirk

 

somebody lied to him.

 

I am no engineer, so this may be stupid, but when things are said and done and the rebuilding begins, does it make since to the rest of you that they need to run levees throughout the city, dividing it up into sections. So if there is a levee breach, only one section of the city floods, while the rest are protected...?

 

Makes sense to me. And while they are at it develop a plan to survive a Cat. 5 strike with minimum damage.

Seems like to me we can develop a way to break apart these storms before they turn into these monsters. If they thrive on warm water why cant we research a way to interject some type of dry ice or cooling agent into the storm. Maybe that sounds stupid but there have got to be people trying some way to stop these storms from becoming so strong.

 

I am no engineer either. This is a valid question and I'm not asking this to be a jerk etc. If you build levees within the city what do you do about roads ? You can't very well run a levee over a street. I'm afraid that New Orleans' problem can't be fixed, its a bowl. Apparently another city in Louisiana faces the same issues, Morgan City.

 

That may be close to impossible for a low lying coastal area like metro New Orleans.

A category 5 hurricane is simply too darn powerful to expect minimal damage, especially from the tidal surge it creates.

Even if you spend billions of dollars, there is no guarantee that nature will cooperate with a plan.

 

I'm a LA transplant living in MN.
Recently in IA, a noticed an area near a river where they must have a lot of flooding. They had a levee system along the river, and where the streets had to cross the river and go through the levee, there was something akin to a big rolling wall / gate to close up the gap when needed. IF that actually works, that would be a great idea in NOLA.

 

New Orleans has several of those gates scattered around the river and the lakefront. They can build other levess, heck they are talking about having to breach a few levies to get water out of some area's like Palq. Parish as they do have more than one. My guess is that FEMA and the Army Corp of Engineers will study again what kind of money they do have and the cost effectiveness of everything and make some decisions about this. But there is no way to ever make a city completely hurricane proof, these storms are just too powerful. Many of the buildings in the Miss. coast area built after Camille were supposedly buil to withstand a category 5 storm and they are now nothing but rubble.

As for ice, man, that would take an amazing amount to cool off the Gulf, they'd have to bring down a large part of Anartica. and then the people they direct it at would really be pissed too.

 

I just don't see any real answers to prevent this from happening. Mother nature just can't be stopped when she doesn't want to be stopped.

Reports say that the lake dropped 2 feet overnight, which is great news. Looks like that's the best and only chance to stop the flooding into the city.