Pretty Gd Read on NO Infrastructure...

motordavid · #1 09-01-2005, 04:06 PM

Good read on the levee/pump system that kept Nawlins' working while it existed below sea level...from the ChiTownTribune via Newsday. BR,md

Uncharted waters
As New Orleans plans to bail itself out, engineers undertake a brash air operation to plug levee breaks

BY JOHN RILEY
STAFF WRITER
Published September 1, 2005

In the best of times, the levee and drainage canal system that protects New Orleans is an engineering marvel - 350 miles of water walls and 21 powerful pumping stations that have allowed a major American city to flourish in a below-sea-level saucer surrounded by water and swamp.

But in the worst of times - like now, in the wake of a crushing assault from Hurricane Katrina - it is an engineering nightmare. And the Army engineers responsible for helping the city begin to bail itself out acknowledged as much yesterday, as they unveiled an unprecedented and untested plan to begin dropping 15,000-pound sandbags from Chinook helicopters to try to plug levee breaks as early as last night.

The problem: The Army Corps of Engineers is resorting to a never-before-tried air operation to plug massive breaks in three canal levees because flooding is too deep to allow trucks to reach the breaches and the water is too obstructed by bridges and debris to reach the sites by barge.

"We prayed that it would not go this badly," said Walter Baumy, chief engineer for the Corps' New Orleans office, in a briefing for reporters. "There was a plan in place and this is much more than was envisioned."

In normal times, levees along Lake Pontchartrain to the north and the Mississippi River to the south and west protect the low-lying city from floods. Drainage canals in the city collect water from storms and the spongy earth under the city, and pumping stations transfer it north to the lake, part of the Gulf of Mexico estuary system.

The system, however, was designed for a Category 3 hurricane. Katrina was a Category 4. Its rain and surge pushed up the level of the lake. Water overtopped the drainage canal levees, scouring their footings from one side, pushing outward from the other, and causing at least three major breaches.

"To use a football analogy, it goes down like a high-low tackle," explained John Hall of the Corps' Vicksburg, Miss., office. "You hit someone at the shoulders and at the ankles at the same time, he's going to go down."

The breaches of as much as 300 to 400 feet Monday and Tuesday in three canals - the 17th Street Canal, the London Avenue Canal and the Industrial Canal - let massive quantities of water from the swollen lake flood 80 percent of the city.

Yesterday, the Corps said water levels appeared to equalize, slowing or halting the seepage into the city. But the breaches have to be repaired to allow the water to be pumped out through the canals.

Experts yesterday said the plan to use helicopters was innovative, but difficult. Although the Corps intends to use spotters to guide the copter crews, dropping bags from the air is not as precise as dumping stone and fill on the ground. The number of bags that have to be dropped to plug a break the length of a football field and 20 feet deep is massive.

"Anything they can do will help, but they don't know if this will do it," said Peter Nicholson, head of a dams committee of the American Society of Civil Engineers' Geoinstitute.

The Corps hoped to begin the air drop on the 17th Street Canal breach, on the city's west side, late yesterday, but was also working on other possibilities. One plan: Using rock and gravel to build up the land from the nearest passable roadway to the breach site, so heavy equipment will be able to pass over the flood waters.

"We'll see how ... [the air drop] works," said Greg Breerwood, a Corps engineering deputy in New Orleans. "This seems to be the quickest and that's why we're using it."

Plugging the breaches will mark only the first stage of draining New Orleans. The Corps also plans to create new breaches in some canals, at locations that will allow sections of the city covered by water to drain out to the lake by gravity.

But the key to emptying the city will be the pumping stations. Every one of them is currently inoperable and there is no timetable for fixing them.

"My opinion is that the stations were inundated," said Baumy. "They need to get in and do a little refurbishment, and get some electrical power to get them restarted."

Beyond the immediate crisis, experts said Katrina seemed certain to trigger a new debate over a costly upgrade of New Orleans' system. "Sometimes," said Nicholson, "it takes a major disaster to loosen the purse strings in Washington."

Copyright © 2005, Newsday, Inc.