This past May, the Army Corps of Engineers released a long-awaited report about the walls along both sides of the 17th Street canal. Through three different methods, the stability of those walls was analyzed and a "Safe Water Elevation" of 6 feet was set. The top of the walls are around 14 feet.
The report is dense, and as such is filled with fascinating factoids which have never been made public.
Buried on page 53 is some very disturbing news. The canal, for around half its length, is almost half full of silt, cutting the drainage capacity significantly.
Read on..
I got this report simply by asking for it. Doing so has already yielded results by my bringing a May, 2006 inspection report included in the appendix to the attention of state and federal officials.
Now there's another serious problem that must be addressed.
The first 57 pages of the report are here:
http://www.box.net/...
And the complete appendix is here:
http://www.box.net/...
On page 53 of the main report (Adobe page 54) is a passage called "Sedimentation."
Here's what it says:
"(3) Sedimentation. The post Katrina surveys show that the accretion has occurred in the canal. Between I-10 and the railroad bridge the lowest canal bottom elevation is El (minus) 10 NAVD or over 7 ft. of sedimentation according to post Katrina surveys. Between Veterans Blvd and I-10 the canal bottom elevation is El (minus) 14 to (minus) 18 NAVD or between .5 to 3 feet of sedimentation according to post Katrina surveys. Between the B/L Station 583+00 and Veterans Blvd the canal bottom elevation is El (minus) 15 NAVD or higher about 4 feet of sedimentation according to post Katrina surveys. Between Hammond Highway Bridge and Station 583+00 the canal bottom is between El -17.5 NAVD and El (minus) 19.5 NAVD (at one location 120 ft south of Hammond the bottom elevation is (minus) 20.0 NAVD) about .5 ft to 2.5 ft of sedimentation. Since the surveys were taken 18 inches of riprap has been placed on the canal bottom from Hammond Highway to the south end of the breach."
So the canal bottom, for nearly half its length (from I-10 to the railroad bridge, which is the southernmost part of the canal, right in front of Pumping Station 6) is nearly half full of silt.
It's hard to imagine this isn't having any impact whatsoever on drainage in this city. A canal that is significantly clogged with debris almost two years after the storm, and no one has noticed? The Corps has even added to the level of the canal bottom with another 18" of riprap.
It's a good bet the other two outfall canals and the Indistrial Canal also have tons of junk on their bottoms. Does this make water rise higher in the canals, making them less safe?
The City of New Orleans is still cleaning silt out of its drainage pipes under the streets, and expects to be doing so for another year, at least. So why isn't anyone doing the same for the biggest parts of that drainage system - the canals? These canals are used during every rainstorm, no matter how minor.