Corps tests system of storm protection

• By JOE GYAN JR.
• Advocate New Orleans bureau
• Published: May 14, 2008 - Page: 4A - UPDATED: 12:05 a.m.

• Print
• Email
• Save
• Reprints
• Twitter
• Share

• Del.icio.us
• Digg
• Facebook
• Reddit
• 

NEW ORLEANS — With the start of the third hurricane season since Katrina less than three weeks away, the U.S. Army Corps of Engineers put floodgates and pumps at four New Orleans-area outfall canals through their paces Tuesday to make sure the equipment — and the workers operating it — are primed.

Emergency preparedness officials from 13 area parishes also took part in the final hurricane preparation and response exercise before the 2008 hurricane season kicks off June 1.

Interim floodgates and pumping stations were tested at three New Orleans outfall canals — the 17th Street, London Avenue and Orleans Avenue canals — and at the Harvey Canal on the west bank of neighboring Jefferson Parish.

Lt. Col. Murray Starkel, deputy commander of the corps’ New Orleans District, said the exercise conducted in response to a mock hurricane named Zeus was a success.

“You’re constantly improving, you’re constantly tweaking the process,’’ Starkel said while water drawn from the 17th Street Canal belched from massive pipes on the Lake Pontchartrain side of huge floodgates near the mouth of the canal. “Everything’s going well.’’

The 17th Street and London Avenue canal floodwalls failed during Katrina, contributing to the flooding that swamped 80 percent of New Orleans. The Orleans Avenue Canal did not breach.

The 17th Street Canal, which separates the east bank of Orleans and Jefferson parishes, has 11 floodgates and 43 pumps — 18 hydraulic, 11 direct drive and 14 bridge pumps — with a pumping capacity of 9,200 cubic feet per second, enough to drain an Olympic-size swimming pool in 10 seconds. The canal has a safe water elevation of 6 feet.

The London Avenue Canal, which breached on both sides during Katrina, is in New Orleans’ Gentilly area and sports 11 floodgates and 20 pumps — 12 hydraulic and eight direct drive — with a pumping capacity of 5,200 cfs. The canal’s safe water elevation is 5 feet.

The Orleans Avenue Canal, located between the 17th Street and London Avenue canals, has five floodgates and 10 hydraulic pumps with a 2,200 cfs pumping capacity. Its safe water elevation is 8 feet, meaning its gates are the last of the three New Orleans outfall canals to close in the event of a tropical storm or hurricane.

The gates at all three canals weigh 11 tons apiece and are 27 feet high when raised and 12‰ feet high when in the lowered position. The gates block storm surge in the lake from entering the canals.

Instead of vertical floodgates that are lifted and lowered, the Harvey Canal has so-called “sector gates’’ that swing open. The canal also is equipped with seven hydraulic pumps with a pumping capacity of 750 cfs. The canal’s safe water elevation is 2 feet.

It takes between 40 minutes and 50 minutes to close the floodgates on the 17th Street, London and Orleans Avenue canals, and only eight to 10 minutes to shut the Harvey gates.

Whether and when the canals’ floodgates are closed depends on a storm’s intensity, path, water surge and landfall timeline. Gates are lowered well in advance of a storm’s arrival.