Posted on 10/04/2005 4:45:07 AM PDT by Maria S
A child's clubhouse, built about 25 years ago by a civil engineer for his son, provides another clue pointing to possible design or construction flaws in the structural failures that breached two canal floodwalls and inundated the city during Hurricane Katrina.
Engineer Gus Cantrell, 60, and son Daniel Cantrell, 33 &150; now a structural engineer himself &150; returned to the family's Pratt Drive house last week for the first time since Katrina struck. They discovered the old clubhouse sitting a few feet from its original location next to the London Avenue canal levee &150; on top of a pile of mud and silty sand about 8 feet high.
The Cantrells believe that extreme pressure from high water pushed soil under the base of the floodwall away from the canal and upward in an arc, something known as a heave. That appears to have raised a mound of earth into the back yard under the clubhouse. The wooden clubhouse's base is now even with the edge of the house's roof, Daniel Cantrell said.
(Excerpt) Read more at nola.com ...
Rove/Bush blew up the levee, everybody knows that. Farrakan says it's true.
Those floodwalls were remarkably light and narrow. For an earthen dam, they were thin. Such light construction demands exacting quality control. Far better to build nice wide levies that can be built to an achievable standard. If this means 300 ft. of property has to be condemned on either side of the canal, I don't have a problem with that. That is legitimate public use.
That said, the levies did what they were designed to do, and no more. If greater protection is required in the future, some land is going to have to be lost.
Rove must be a structural engineer to get that levee to do that.
Not really. There's no limit to what you can do with captured UFO technology. ;o)
Where is Calypso Louie with the offical Muslim lab report
showing traces of 'cordite' in the mud?
One of the few things that CA does right is zoning in flood plains.
I sometimes play at a golf course along a creek bed in a pretty ritzy neighborhood. The land would clearly be worth much more as housing, but would be subject to flooding, so it is not developable.
I keep wondering if there isn't some use for most of the land in the flooded areas of NO, which would not lead to a future disaster.
Put in golf courses, amusement parks ala Disney, office buildings with parking on the lower levels, apartment buildings with lower level parking, public parks with sports fields, horse race tracks, casinos with lower level parking, etc.
Sure there would be economic consequences to a flood, but not a civil disaster.
Probably won't ever happen--it would bring higher income people into the area and permanently displace low income. Nagin would lose his voting block.
Sorry, but I don't believe any of this. Th CIA convoy that regularly delivers crack and AIDS into the black neighborhoods was diverted to the levees loaded up with C-4 to make sure the destruction was complete.
Not if it displaces minorities, then it's overbearing racist government action.
Fact is that the construction firm which built this levee informed the Corp of Engineers of the substrate problem at the time of construction and requested a change order in the amount of $809,000 to correct the problem. The change order was denighed.
Well, there should certainly be no problem acquiring the necessary right-of-way now.
I wonder, when all is finally sifted out, whether it won't turn out that the levee failures were due to burrowing nutria.
Did we not also hear of "sand boils" when Rita rolled by?
Few things in this world have the desctrutive force of moving water.
You know what would be pretty slick? The reconstruction could build up the avenues parallel to the flood walls, so the first block is 10 ft above the flood line, with each subsequent block stepping down one or two feet, until you reach your base elevation. That way you would have a huge earthen dam with people living on top of it. You would have to restrict the land to surface use only, and have some controls in place to make sure nobody does anything foolish, like digging a swimming pool. But that way the land would not have to be lost.
"There's no limit to what you can do with captured UFO technology. ;o)"
Naaahhh Cheney brought it back with him through the Haliburton Stargate.
One thing I don't understand is why the canal is there in the first place. Apparently the neighborhoods where flooding began are a sufficient distance from Lake Pontchartrain. But then this safety margin is erased by having a canal go from the lake to a point where only a narrow levee protects the whole city.
Well, the Industrial Canal is there for navigational purposes. But the other canals seem to be for flood control. Water is pumped from the bottomland over the wall and it drains into the lake. Why this water could not be pumped through large concrete pipelines, I don't know.
I can prove conclusively that levees facing Lake Pontchartrain, 17 feet tall, above sea level, west of the 17th Street Canal, 13.5 and 18 feet ASL east of the 17th Street Canal, and 17.5 feet on either side of the London Canal were all topped by storm surge and wave action. The 17th Street Canal and London Canal floodwalls are 14.5 and 14 feet ASL respectively, and were almost certainly topped as well. In my opinion, this topping did not lead to significant scouring or to the levee failures at those points.
That said, examination of the post storm images of the 17th Street Canal Breach and one of the London Canal breachs show that the source of this story's claim to a heave moment (rotation of the fill under the floodwall's base) is probably also not the cause behind the breaches. It is possible that he is referring to the other London Canal breach, in which case my objection may not apply.
If my surmise as to the the sequence of the failures is correct, we will never be able to directly prove it, but the indirect support for the mechanism is extremely difficult to argue with.
For those of you that have been following the series of articles posted here, I expect part 5, "How and Why New Orleans Flooded" in the one to two week time period, and it will include an examination of those specific breaches in depth. For those of you interested but not on the original ping list, you can follow the trail starting here:
http://www.freerepublic.com/focus/f-news/1489838/posts
Drainage pipes would serve the initial purpose, but they would need to be of a diameter such as to equal the cross section of the canal in capacity. The canals measure roughly 14 by 50 feet, which translates to a pretty big pipe. At that point, a canal is less expensive to construct and offers a benefit/liability that pipes do not, unlimited capacity, if you are willing to overfill the canal.
This can and did cut both ways in the pre-dawn hours prior to Katrina's arrival, with certain areas pumped dry(er) while the receiving canal overfilled and lightly flooded other areas.
NO levee related story....
http://www.wdsu.com/news/5055164/detail.html
SOUTHPORT, Fla. -- A construction company based in the Florida Panhandle has denied allegations in a federal lawsuit that it was partly to blame for the failure of a New Orleans levee after Hurricane Katrina.
Daniel Becnel Jr., a Reserve lawyer, sued Gulf Group Inc. of Southport, a Panama City suburb, in New Orleans last week. He claims vehicles and heavy equipment the company left on the 17th Street Canal levee contributed to its failure. Gulf Group was building a bridge near the levee.
Thanks for the ping.
I saw an aerial image of the 17th Street Canal before the levee failed in which there was a a construction barge just southeast of the Hammond Highway bridge, but I can't locate it now.
In any event, I've looked for the barge in the post storm imagery and have been unable to spot it, inside or outside the levees. It could have been removed prior to the storm, it could be well upstream now, or it might have gone through the breach and sank. Given the similarities between the London Canal breaches and the 17th Street Canal breaches, I am currently operating from the assumption that the construction barge played no part in the 17th Street Canal breach. (Not to be confused with the grain barge located on the wrong side of the breach east of the Industrial Canal, which probably didn't cause that breach either.)
As to dredging being a cause of the failures, it is mathematically possible. It depends on how close to the sides of the canal they dredged and the exact structural cross section details of the levee/floodwall. Given that the CoE would almost certainly have supervised the dredging, and that I've yet to see gross stupidity on the part of the CoE, I rate the likelihood of dredging being a direct or contributory factor in the 17th Street Canal breach as being very low.
" $809,000 to correct the problem"
I don't buy it. There is no way a few million would be enough to build a proper levee system. This is tin-foil land with a political agenda. Levees fail no matter what. They just do.
Canals in low-lands are necessary for port operations and drainage. Ever been to Florida?
jeffers, good call.
Plus drainage pipes need to be cleaned from time to time. Surface draining is much less expensive.
You are right about that but that is NOT what we are talking about here!
The contractor putting in this levee (for millions) recognized the fact that the substrate (the material upon which the levee was to be built) was not sufficient to hold the weight to be placed upon it in several locations and so informed the Corp. of Engineers in writing of this fact. At the same time, the contractor requested a change order in the amount of $809,000 to correct the substrate problem before proceeding. (This $809,000 would have been in addition to the monies already in their contract for the job.)
The request for change order was denied and the levee was built on top of the known substandard substrate material!
A child's clubhouse, built about 25 years ago by a civil engineer for his son, provides another clue pointing to possible design or construction flaws in the structural failures that breached two canal floodwalls and inundated the city during Hurricane Katrina.
Thanks for the ping, CD.
I have been involved in levee strengthening projets on the American River, specifically in Sacramento where a backhoe digs a trench approx 3-4 wide, and almost 100 feet deep. The trench is backfilled with a soil/cement/bentonite tokeep the water on the proper side. Here's a backhow used in the project. BTW, this work runs about 3-5 million per mile of levee.
Backhoe, not backhow.
Cool tool.
I stand by my opinion that the problem with the Corp is not techinical or financial. These guys are engineers turned into lawyers.
If they get a project and people let them alone (fat chance) the project will be fine.
I'd bet a manatee steak (the other, other white meat) that down under the controversy is some meddling politician or EIR.
I like that, with a grout curtain being impractical and steel being steel with its affinity for oxidation and corrosion in salt environments.
Can you backfill under pressure, as a slurry that sets up later, or do you have to keep the trench unwatered until you've backfilled it?
In order to keep a trench like that open, it is filled with a bentonite slurry that has a higher density than water. That keeps hydrostatic pressure working outward on the trench walls.
When the backfill material is placed, it is dumped at the top of the trench and it slides down a ramp of unexcavated material or previously placed backfill in such a way that it does not drop through the liquid slurry and separate as it reaches the bottom.
Glancing through Google, this reference seems like a fairly decent one. If this doesn't answer all your questions, let me know.
http://www.tceq.state.tx.us/comm_exec/forms_pubs/pubs/rg/rg-282_189585.pdf
Sometimes in lieu of a slurry trench, a jet-grout wall or soil mix wall is used. Those consist of overlapping vertical cylinders, and on deep holes, if the alignment isn't perfect (With in one half of a percent) the wall/curtain is flawed and will not perform as necessary. The slurry trench is guaranteed by the nature of excavation to provide 100% coverage, and long as the backfilling method is done correctly
Big Dig (in Boston) used that parts of that technology: But not everywhere. Expensive.
But what is the velocity of water flow in the canal? I don't think the cross sectional area of a pipe would have to be nearly as large, because a pipe can operate at much higher velocities.
At some point, however, you have to trust the engineers who have been scratching their heads over this problem for the last couple hundred years or so. To my mind, the best solution involves either condemnations of large areas in order to build proper earthen dikes, or a decision to not build in these areas at all.
Hey, dude! You might want to check out Post #29...
Got it, thanks.
I was interested because there is a chemical plant here that had contaminated the surrounding area and they were looking into similar technologies to prevent the contaminants from further leaching out and affecting the groundwater and the surrounding neighborhood. They were looking at a curtain some 200 feet deep, surrounding the plant, which is roughly a mile square in area.
To All, bentonite can be considered, for non-engineering purposes, to be "clay", which may help in understanding the technology under discussion.
Got it, thanks.
I was interested because there is a chemical plant here that had contaminated the surrounding area and they were looking into similar technologies to prevent the contaminants from further leaching out and affecting the groundwater and the surrounding neighborhood. They were looking at a curtain some 200 feet deep, surrounding the plant, which is roughly a mile square in area.
To All, bentonite can be considered, for non-engineering purposes, to be "clay", which may help in understanding the technology under discussion.
Yeah, simply put it's a Wyoming sodium montmorillonite clay. Well, the good brands, anyway.
For applications 200 feet deep, a backhoe will not work. IIRC, the deepest digging backhoe is owned by RECON from Houston. GEOCON is another excellent slurry trench contractor.To go 200', an clamshell on a crane will be needed. In this case, I think TREVIICOS is the company to go to.
ICOS, predecessor to TREVIICOS did the first structural slurry walls in America at the World TRade Center. I had the opportunity to work with several people who were involved with that project (All old guys from Italy).
Now that's a backhoe!
When I started doing construction work in the sixties, you were lucky to have a tractor on the site, and if it had an end-loader and a backhoe, you were really "uptown"-- that was a lot of labor-saving help back then.
Now, I see large machines like that tracked excavator everywhere.
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