[StBernard] City still vulnerable

[Westley Annis]

City still vulnerable
Posted by The Times Picayune May 08, 2007 7:54PM

Just weeks before the start of a new hurricane season, New Orleans'
hurricane levees are incomplete leaving the city at risk from even small
hurricanes.

Staff writer

The New Orleans metropolitan area will enter the 2007 hurricane season with
an incomplete levee protection system that could fail on its eastern and
southern borders -- even during smaller hurricanes, independent critics and
officials with the Army Corps of Engineers agree. 

Lt. Col. Jeffrey Bedey, commander of the corps' Hurricane Protection Office
that oversees levees on the east bank of the Mississippi River, agreed that
the protection offered levees, walls and gates does not yet meet levels
authorized by Congress before Hurricane Katrina. 

But major strides have been made since the August 29, 2005 disaster, he
said. 

"In general, the repairs have strengthened the levees enough to prevent
another catastrophic breach, but haven't yet raised them enough to prevent
overtopping in places.Even a strong Category 2 hurricane entering the Gulf
Intracoastal Waterway from Lake Borgne could overtop levees guarding eastern
New Orleans and the Lower 9th Ward to the north, and St. Bernard Parish to
the south. As during Katrina, that channel can still funnel high water into
the Industrial Canal, where it would top levee walls on its western side,
which remain as much as two feet too low. 


That west wall has not yet been rebuilt following Hurricane Katrina in 2005.
But the corps has added concrete or cemented rock on its back side to block
the dirt beneath from being eroded if the wall is topped, Bedey said. Along
some wall sections throughout the levee system, more earth has been added to
reduce the "stickup" of the walls to no more than 6 feet above ground.. 

As a temporary safeguard, the agency may install metal and fabric baskets
filled with dirt and rubble to make the walls higher, and build a barge gate
in the GIWW to stop surge from entering the Industrial Canal, he said. The
gate, if built, would not be finished until next hurricane season. 

Robert Bea, a civil engineering professor at the University of
California-Berkeley, also has raised questions about the ability of a
rebuilt wall on the east side of the Industrial Canal to withstand a
Katrina-strength storm surge. 

Bea, who is advising plaintiff attorneys in a class action lawsuit against
the corps for damages stemming from the 2005 levee failures, said he
recently found evidence of water seeping beneath the new wall and bubbling
up from around a telephone pole less than 50 yards away during a recent
visit to the city. A video of a puddle Bea says is the result of the seepage
accompanies a National Geographic Online feature on levee problems published
Monday. 

Bea argued that the seepage may be the result of the corps using sheet
piling only extending 19 to 23 feet below sea level beneath the new wall,
which he said places the tips in a soil type listed as "marsh" on some corps
diagrams, Bea contends. 

But the Corps disputes that assessment. Samples taken along the wall since
Katrina indicate that the soils in the zone marked "marsh" on some diagrams
actually are "fat clay," a much stronger material, said Richard Varuso, a
senior geotechnical engineer with the corps. 

And Varuso said tests of six water samples taken from puddles along the
canal show that it is fresh water -- probably from broken water or sewer
mains -- and does not match three samples of brackish water taken from the
Industrial Canal, undercutting Bea's assessment of the weakness in the flood
wall. 

Varuso said the samples have been sent to an independent laboratory for
verification. 

In the aftermath of Katrina, Varuso said, the corps rebuilt the wall along
the Lower 9th Ward as an inverted T wall, with concrete paving behind it to
stop overtopping water from eroding the floodwall's back side, causing a
collapse. 

The walls is anchored by70-foot-deep H-beams, driven diagonally and attached
to the wall at six-foot intervals.

West Bank weak spots 


Both corps officials and the agency's critics agree on the second weakest
link in the hurricane protection system: the mostly incomplete levees on the
West Bank. 

Hassan Mashriqui, a research engineer with the Louisiana State University
Hurricane Center, said his modeling of storm surge indicates that a
hurricane hitting the coast west of the Mississippi River could push water
through the Barataria basin and Lake Cataouatchie into Westwego, Belle
Chasse, Harvey and Waggaman. 

A lengthy section of levee between the Harvey Canal and the western part of
Lake Cataouatchie remains incomplete. Also unfinished are levee walls
connecting a new Harvey Canal floodgate to earthen levees on the canal's
east side, said Julie Bigne, a corps West Bank project manager. 

Another project, to raise earthen levees along the Algiers Canal, which is
part of the Gulf Intracoastal Waterway, also remains in progress, corps
officials said. As a stop gap measure, the corps is building a temporary
surge gate in the Company Canal, just north of Bayou Segnette State Park,
where a section of levee wall was determined to be inadequate. 

Although the barge gate won't be finished until August, the height of the
hurricane season, corps officials say that in an emergency they can close
the opening in the new structure with metal beams already stored at the
site.

Temporary fixes 

Back on the eastern side of the Mississippi, the corps says it has
temporarily addressed concerns that a floodwall along the Duncan or West
Return Canal, on the border between Jefferson and St. Charles parishes,
could be pushed over by storm surge moving through wetlands from Lake
Pontchartrain. 

Contractors have installed deeper sheet piling along the northern end of the
weak I-wall along the canal, said corps project manager Mervin Morehiser.
The corps also is replacing antiquated sheet piling along the west side of
the Louis Armstrong Industrial Canal with thicker, 60-foot-long pilings. The
entire wall will eventually be replaced with a stronger, modern structure,
he said. 

And a new levee behind wetlands along the lake in St. Charles Parish between
the Jefferson Parish line and the Bonnet Carre Spillway has been raised to a
minimum of 10.7 feet, with some parts already raised to 17 feet. 

Before Katrina, much of the levee hadn't been completed. 

"We eventually will have a levee that's 15 or 16 feet high," Morehiser said,
after the second lift is added and settles. 

St. Bernard vulnerable 

Corps officals and agency critics also are arguing over the adequacy of
rebuilt earthen levees lining the Mississippi River-Gulf Outlet, which
protect Chalmette and St. Bernard Parish from storm surge flooding. 

"The whole MR-GO levee is made up of material that's shown to be eroding
even from the rain," said Ivor van Heerden, deputy director of the LSU
Hurricane Center and the head of Team Louisiana, a group of scientists and
engineers that investigated the causes of levee and floodwall failures
during Katrina for the state Department of Transportation and Development. 

Though the corps has raised the levees and bolstered them with new soil, it
hasn't armored them to prevent erosion. 

"If another Katrina hit, waves will chew up the levees again and you'll have
more catastrophic flooding," said van Heerden, who also is a witness and
consultant for plaintiff attorneys in a class action lawsuit against the
corps. 

Bedey said the corps won't be able to protect the back side of the MR-GO
levees with rock or concrete armoring until the corps completes work to
raise the levees to protect the area from a 100-year hurricane, which won't
be until 2011. 

In the meantime, he said, the corps used firmer soil in the levees and
improved the slope angle to reduce the chance that overtopping will erode
the earthen barrier. And he said the grass covering is in good shape, after
more than a year of growth, good enough for him and other corps officials to
have recently practiced their golf swings on it. 

Corps officials also agree with critics that two gates in earthen levees in
St. Bernard, at Bayou Bienvenue and Bayou Dupre, also could pose problems in
a hurricane, although they differ on the reasons. 

August Martin, a project manager with the Hurricane Protection Office, said
the top of the gates are only 16 to 16.5 feet above sea level, while the
adjacent levee was rebuilt to 20 feet. That means that storm surge could
enter the wetland buffer between the corps levee and the lower, parish-owned
40 Arpent levee behind it over the two gates. 

But he said the narrow sections of earthen levee connecting to the gates,
which washed away during Katrina, were rebuilt with rock and concrete
armoring to withstand scouring. 

Van Heerden said the armoring used to strengthen the connections make them
higher than the adjacent earthen levee, which could result in a failure. 

As surge hits that part of the levee, van Heerden said, its energy will look
for the weakest spot to erode, which will be the earthen levee next to the
armored section 

MR-GO still a concern 

Adding to the concern, van Heerden said, is a lack of Congressional action
to close the MR-GO channel, which would allow the corps to build an earthen
berm or lock across the channel at Bayou la Loutre, reducing surge moving
north towards the northern levee on the GIWW. 

"If there's another Katrina, both sides of that system would be overtopped,
and you would see flooding, he said. 

Corps officials have disagreed with van Heerden and others about how storm
surge is affected by the MR-GO, contending that surge water moving east from
Lake Borgne, rather than through the shipping channel, caused most of the
flooding in St. Bernard and eastern New Orleans during Katrina. 

But Bedey said the corps remains on track to complete its recommendations on
how best to close the channel, which will be sent to Congress for approval
this fall. 

Despite the weak spots, Bedey said the corps has been successful in
dramatically reducing the risk from storm surge in a number of locations,
compared to before Katrina. 

That includes the installation of gates on the 17th Street and London and
Orleans avenue canals, which will eliminate the risk to floodwalls along the
canals. 

Problem pumps designed to move rainwater in the canals over the gates into
Lake Pontchartrain have been repaired and successfully tested at the 17th
Street and London Avenue canals, Bedey said, and are expected to be repaired
and tested at the Orleans Avenue canal by June 1. 

Mark Schleifstein can be reached at mschleifstein at timespicayune.com or (504)
826-3327.