- The Washington Times - Saturday, May 24, 2008

ASSOCIATED PRESS

A stronger flood-control system designed to prevent the swamping of parts of downtown Washington and the Mall during a major storm must be in place by November next year, officials said yesterday as they began to work on ways of shoring up existing flood barriers.

The deadline comes from an agreement between the District and the Federal Emergency Management Agency after FEMA drafted new projections last year predicting major flooding in the city if a big storm were to strike.

If adopted, the new FEMA flood zone maps could force hundreds of homeowners in the affected area to buy flood insurance and lead to stricter building codes that could complicate construction of new federal and office buildings.

FEMA agreed in April to hold off implementing the map to allow more time for organizations including the city government, the Army Corps of Engineers and the National Park Service to design and build a system stronger than current plans to hold back the Potomac River.

If water rose rapidly, the city would rely on levees and hastily erected sandbag and earthen walls. But the Army Corps of Engineers deemed the plan inadequate in the wake of Hurricane Katrina, which overcame New Orleans flood barriers in 2005.

The updated FEMA map depicts a wide arc of water running through large portions of the Mall, federal office buildings off Pennsylvania Avenue and more than 1,000 homes mostly south of the Capitol.

Museums such as the National Gallery of Art and federal buildings such as the Commerce Department could be under as much as 10 feet of water if flooding breached the current flood-control network, according to the forecasts.

“What we are looking at is multiple government buildings being at risk,” Glenn DeMarr of the National Park Service said at yesterday’s meeting, which also included officials from the D.C. government and the Army Corps of Engineers. A formal public hearing on the project is scheduled for June 10.

Much of the effort will be focused on 17th Street, which cuts across the Mall near the Washington Monument. The street would probably act like a spigot during a large flood, with water flowing up it then down Constitution Avenue into the Mall.

“If we are going to get a big event, it is going to go right down 17th Street,” said Steve Garbarino of the Army Corps of Engineers.

A levee was built in 1939 that runs between the Lincoln Monument and Washington Monument. But to plug 17th Street, a sandbag wall would be quickly built, backed up by an 8-foot earthen embankment if the water kept rising. The sandbag plan has been tested, but the embankment has not.

In its review after Katrina, the Army Corps of Engineers concluded building the makeshift walls could be cumbersome during a storm and said a more reliable system was needed.

Possibilities include raising the level of 17th Street or installing a system where panels that form a wall could be quickly put into place if water levels rise.

“We want to see something out there that is permanent,” Mr. Garbarino said.

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