Oops, the big guy loses patience after all

Seems like folks prayed that the Big Easy would not be wiped off the map, but forgot to ask the Big Guy not to flood it.

Under normal circumstances, here is how New Orleans is drained: It isn't possible to pump stormwater all the way from the center of the city to the levees. Instead, gravity is used to do most of the job. There are canals raised above the level of the city that run along the old routes of the bayous that used to surround New Orleans. Many of them have natural levees that are a few feet above sea level that gradually slope away from them, and that have been reinforced with man-made levees on top of them. In the rest of the city, water is pumped into these canals by large diesel-operated storm pumps. Cross-canals have been built to carry the pumped stormwater from these canals to Lake Ponchartrain, because it typically has a lower and more stable water level than the Mississippi River. These cross-canals have minimal natural levees and are protected by large dikes or seawalls.

These cross canals have always been the weakpoint in New Orleans's levee systme. The seawall along Lake Ponchartrain is quite stout and rests on a natural levee that is a few feet above sea level in the first place, and the same with the Mississippi levees and the central canals' natural levees. But the cross canals' levees are nowhere near as stout. Apparently hundred-foot sections of some of these cross canals have just... disappeared. Melted away in the storm surge. Causing the bowls between them to fill with water, until finally the water comes up above the (much lower) levees protecting the storm pumps and submerges them.

Basically these levees aren't going to be fixable until the bowls between them finish filling up, until then dropping sand on their former locations out of helicopters is pretty much pissing in the wind. They will basically have to be fixed by floating barges in from Lake Ponchartrain. The first barges will be full of dirt and gravel and the equipment to dump it off the barges into the water in order to create temporary levees. Then comes the chore of creating permenant levees. Large steel bulkheads will be rammed deep into the subsoil into the locations where the levees should be, the water will be sucked out, and large footings created so that the resulting levee will basically float on the mud and muck that New Orleans is built upon. Then a shell will be created with an inner bulkhead on top of this footing. Concrete will be poured to create a concrete shell. The inner bulkhead will be removed, the shell filled with dirt, and then the outer bulkheads removed and the next section, which interlocks with the previous section, will then be constructed. This is not unusual by any means, New Orleans is expert in building stuff off of barges, I remember when they expanded I-10 to the west of the city watching the barges float along below with construction equipment and construction materials. But it doesn't happen overnight. While dumping sand off of helicopters looks exciting, that's not what's going to fix the levees, it's going to take heavy equipment on barges, and while there is a lot of such equipment in Louisiana, the current state of emergency is going to make it hard to round it all up and get started.

Then once temporary levees are in place, they're going to have to pump out the city... which is not going to be an easy task. The pumps are all underwater. So they'll have to build temporary levees around the pumps and pump out the pumps first. The diesel engines which run the pumps are likely ruined by the salt water. So they're going to have to replace those diesel engines and then overhaul the pumps themselves, which are not designed to be immersed in salt water and are going to need careful drying out and lubricating before they're usable.

Once the pumps are back operational, it won't take as long to pump out New Orleans as some people fear. The pumps are designed to evict about 12 inches of water per day. New Orleans averages about 6 feet below sea level. So it'll take about a week to pump it all out. But before that can han happen, the parts of the city where the levees have failed will have to be completely flooded so that the levees can be repaired, because the breaks are simply too large to repair while the flood is in progress.

The question is whether New Orleans will still be a viable city at the end. Having 2/3rds of the city underwater for what will likely be at least a month is not conducive to commerce. The older parts of the city, built above sea level on natural levees, will remain pretty much unscathed of course, and those are the primary tourist draws. But it will take literally years to rebuild I-10 east of New Orleans, meaning that shipping traffic will likely continue upriver to the industrial area south of Baton Rouge, where it can be unloaded to trains and trucks to go to the east over I-12.

In short: If you have any CSX stock, sell. (CSX is the main freight line from New Orleans to points east). Norfolk Southern, on the other hand, looks like a good bet (via KCS they are one of the main lines out of Baton Rouge to points east). And if you want a good time in the Big Easy, it may be a few decades... or never, depending upon whether America still has the ability to fix things in a timely manner. I'm not sure nowdays. The days of America as a can-do nation that could do anything seem to be fading fast, with "can't-do" being the prominent feature of modern America. Want good health care for all Americans? Back in the days of "can-do America", America would have said "Sure!" But in today's "can't do America", America says "Can't be done." Want to go to the moon before the end of the decade? "Can't do it." Sadly, restoring New Orleans to her former prominence as a major port city may be another "Can't be done" in the new "can't do" America....

- Badtux the Soggy Penguin