RISK

Unfinished levee leaves Washington agencies vulnerable to storm surges

Under the shadow of the Washington Monument and just north of the National World War II Memorial in Washington, D.C., a concrete levee remains unfinished, surrounded by dirt and a tall wooden fence. The Potomac River, which has surged into the District multiple times during hurricanes in the past, flows about a half-mile away from the project.

D.C.'s levee system is meant to hold back 457,000 cubic feet of water per second during what the Federal Emergency Management Agency has designated as a 100-year flood, protecting an area that extends from the Federal Triangle to the Capitol and curves down to just north of Fort McNair in southwest Washington.

Without this structure, the zone that is vulnerable to storm surge flooding includes many of the District's key institutions, including the Internal Revenue Service headquarters, the Department of Commerce, the Department of Justice and the National Archives, as well as several venerable cultural attractions, like the National Gallery of Art and the Smithsonian Museum of Natural History.

But in mid-May, the Washington Post reported the $4.1 million project was on hold. The overseeing agency, the Baltimore District of the Army Corps of Engineers, fired the contractor responsible for the job, Hirani Engineering of Jericho, N.Y. The project was supposed to be completed in the summer of 2011 but is now stymied at two years behind schedule.

Hurricane season began June 1, and National Oceanic and Atmospheric Administration officials announced that this year's season may bring twice as many hurricanes as are normally expected, as the mitigating effects of El Niño will be absent (ClimateWire, May 24).

'We just can't continue to live on our luck'

In a city where Capitol Hill -- sited safely above historical flooding levels -- has been in a political gridlock for years over what to do nationally about climate change, the saga of the levee is a kind of mirror of the capital's difficulties in dealing with either the politics or the engineering involved in adapting to the threat of more severe weather.

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The original levee system, a series of earthen berms that stretch from north of the Lincoln Memorial to the Washington Monument, was completed in 1939 after a 1936 flood damaged much of downtown Washington and transformed the Jefferson Memorial into an island.

Gaps in this levee at 17th and 23rd streets Northwest are now filled with sandbags and Jersey barriers during flooding events. But after Hurricane Katrina, the Army Corps re-evaluated this system and found that temporary sandbags at 17th Street would be inadequate to protect against a 100-year flood.

"The truth is, none of our levees in the region are actually acceptable," said Amy Tarce, an urban planner at the National Capital Planning Commission, who said she confirmed this with the Army Corps.

According to documents provided by the NCPC, a 10-foot barrier is needed on 17th Street to withstand FEMA's 100-year flood scenario for the District. Sandbags are ineffective at this height, explained Christine Saum of the NCPC, who was involved in planning the levee's design.

Also, unlike a sandbag barrier, the planned levee "has been actually engineered to withstand the pressure of the water," Saum said.

A spokeswoman for the Army Corps, Ashley Williams, said a replacement contractor has not yet been hired, but the agency hopes to have a new timeline for the project established by the end of June. Williams could not give details on the contract's termination except to say, "Significant progress that needed to be seen was not made."

Del. Eleanor Holmes Norton (D-D.C.), who in 2010 secured $5.8 million in federal stimulus funds to improve the existing levee infrastructure, said she was "very concerned" about the delay.

"I'm told it was financial troubles that kept [the contractor] from getting it done," said Norton, adding that the project's surety company is conducting an investigation.

"This work needs to be done as we are being hit across the country with unprecedented weather," she said. "We were very fortunate the last time there was flooding in this region that it didn't come to the Mall, and we just can't continue to live on our luck."

A quadruple threat

In terms of flooding, the District is faced with a quadruple threat, explained Gerald Galloway, professor at the University of Maryland's Department of Civil and Environmental Engineering. In addition to a hurricane storm surge, heavy rainfall can cause the Potomac and the Anacostia rivers to swell significantly, as demonstrated by a 1936 flooding event when ice breakup and intense rainfall runoff caused waters to rise more than 28 feet above flood stage.

2006 saw evidence of a third kind of flood, when a downpour in late June resulted in 3 feet of water on Constitution Avenue, shutting down the IRS headquarters, the Commerce Department, the Justice Department and the National Archives.

Also, "we're all subject to sea-level rise, and Washington is no different," Galloway said. A 2012 University of Maryland study predicted that sea-level rise will cause waters around D.C. to rise about 4 inches by 2050, although both Galloway and Tarce warned that this estimate is far from certain.

Galloway and his colleague Ed Link, a senior research engineer at the University of Maryland and former Army Corps director of research and development, are concerned that the increasing threat of hybrid storms like Superstorm Sandy will be exacerbated by sea-level rise, leaving Washington especially susceptible to flooding events.

"Everyone now is focused on meeting the challenge of the 100-year flood," Galloway said. "That's probably far too low a level of protection for the iconic nation's capital."

According to the Army Corps, a 12-foot storm surge on top of the 6-foot flood stage at the base of Wisconsin Avenue in Georgetown could result in as much as 4 feet of water at the base of the 17th Street levee.

But based on his examinations of the Army Corps' data, Galloway estimated that during a 500-year flooding event, brought on by a powerful hurricane or hybrid storm, floodwaters could breach the levee, surging onto Constitution Avenue to depths of at least 12 feet. With sea-level rise, he said, the waters would rise even higher.

"I think if we talk about the future, the thing that we need to worry about most are these hybrid type of events," said Link, who led the forensic analysis of Hurricane Katrina.

The drainage infrastructure in FEMA's 100-year flood zone is unable to handle the massive volumes of water that could come with such an event. A 2011 federal study determined that the storm sewer on Constitution Avenue was ineffective in funneling water out of the area during the 2006 flood due to its small size and low elevation.

Because of these issues with interior drainage, the Federal Triangle will still fall within FEMA's 100-year flood zone after the levee's completion, explained Phetmano Phannavong, floodplain manager at the D.C. Department of the Environment.

"It's just one solution. One solution is not going to solve everything," Phannavong said.

How many agencies does it take to build a levee?

Although several efforts and proposals are in place to try to improve this situation, it won't be easy. Unlike in other cities, a dizzying number of federal, regional and local players must coordinate to cope with Washington's flood risk.

"Because of the unique setup here in Washington, D.C., with all the jurisdictions that kind of carve out their own little area, when you're talking about something like storm surge flooding and climate change, it doesn't just affect your little jurisdiction, it affects the whole area," said Tarce of the NCPC.

Nine agencies needed to collaborate for the 17th Street levee project alone, including the Army Corps, the NCPC, the National Park Service, the District Department of the Environment and the District Department of Transportation.

Tarce said the NCPC is working to "get everybody in the same room" to better understand the District's increasing vulnerability to extreme weather events and other climate-change-related stressors. She expects that this effort, called the Monumental Core Climate Adaptation Initiative, will produce a report by spring of 2014.

Figuring out the details, Tarce said, will be challenging: "When we start talking about sea-level rise, it's not as simple as just [saying] that there's going to be a 1-foot rise in, let's say, 100 years. ... We're very careful not to be quick and say this is what's going to happen with sea-level rise until we have the science."

Phannavong said the many parties involved in building the levee are also trying to coordinate under the Army Corps' Silver Jackets program, which provides interagency support to address flood risk management.

To give agencies a better idea of what they are up against, Galloway and a group of other engineering professors from the University of Maryland, the University of the District of Columbia and George Mason University have also proposed to conduct a thorough risk assessment for the region, hoping to save the District from significant damage should the worst occur.

"All the information points to an increasing number of severe, intense flood types," Galloway said. "Is the District adequately prepared as we move into the 21st century? No. There's a long way to go."

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