Corps revises London Ave. Outfall Canal ICS operating procedures

Published Sept. 8, 2009
NEW ORLEANS –The U.S. Army Corps of Engineers has modified the operating procedures for the London Ave. Outfall Canal Interim Closure Structure to close the gates when the Lake Pontchartrain level reaches 2.5 and rising for both tropical and nontropical events.
During heavy rainfall in March 2009, water levels in the canal approached the maximum safe water elevation at the Harrison Avenue gage as a result of New Orleans Sewerage and Water Board pumping and an above normal lake level. Engineering analysis of this real-time data led the Corps to refine the hydraulic modeling of the canal. This modeling provided the data necessary for redefining the best operating procedures to reduce risk to the public.
Previous procedures called for closing the gates when the lake-side gage reached 4 feet and rising during tropical events. Lowering that elevation and operating during nontropical events reduces the risk of exceeding the canal’s 5-foot safe water elevation. It also maximizes the pumping capacity of the S&WB pump stations during heavy rainfall.
“This change will lessen the chance of localized flooding,” said Chris Accardo, chief of the Operations Division at the New Orleans District. “We’re doing this because this is the right thing to do to reduce risk.”
Further analysis determined that the operating procedures for the 17th Street and Orleans Avenue canals are not affected by the combination of high lake stages and intense rainfall. No operational changes are required for these structures.

Release no. 09-062