Big Easy's nightmare could also be Big D's

[TexasStooge]

As in New Orleans, the right storm could overwhelm local levees

By JAMES M. O'NEILL / The Dallas Morning News

DALLAS, Texas - Yes, it could happen to us.

Dallas, like New Orleans, could find itself underwater.

If Hurricane Rita had roared through just west of Dallas, stalled over Arlington and dumped as much rain here as it is expected to drop on East Texas, the levees that keep Dallas dry could very well have been breached, flooding a sizable swath of the city.

Downtown Dallas relies on a much-compromised 30-mile levee system to keep it dry from the Trinity River. Because of extensive development in the counties north and west of the city, the levees, completed in 1958, can no longer handle the severe storm runoff they were designed to contain.

Dallas is therefore now vulnerable to a far less serious storm breaching the levees and flooding business and residential areas that equal about 20 percent of the city's taxable property value.

With only a day or so of warning, city officials would need to coordinate the swift evacuation of an estimated 100,000 people who live or work in flood-prone areas on either side of the Trinity.

The flooding would also complicate the city's standard emergency plan, since key shelters such as Reunion Arena and the Convention Center, as well as the city's emergency command post beneath City Hall, would all be flooded.

Just as in New Orleans, where plans were in the works to fix a levee system that failed catastrophically and allowed a huge storm surge from Hurricane Katrina to swamp that city, Dallas officials have $340 million worth of improvements on the drawing board to restore the levees' ability to contain runoff from the type of storm they were originally built to withstand.

"If anyone does not think that a flood is possible in Dallas, I beg to differ," City Council member Ed Oakley wrote to a skeptical constituent recently. "It is not only possible, but could be a reality, just as the models [showed] New Orleans's levee system under certain conditions could fail, and did."

City officials now worry the massive post-Katrina rebuilding effort that the nation plans for New Orleans could make it far more difficult to secure vital federal funding for the plan to improve Dallas levees, which is scheduled for completion around 2014. Already this month, $4 million dedicated to the Dallas project has been redirected to New Orleans.

"Funding delays elongate the project," said Greg Ajemian, Trinity River Floodway coordinator for Dallas. "We're always up against a clock with Mother Nature."

Worst-case scenario

Hurricane Rita swept north on Saturday too far east of Dallas to cause flooding here. But under the right conditions, a tropical storm similar to Rita and saturated with water from the Gulf of Mexico could move north into the Dallas area, then meet a cold front coming south, dumping 11 inches or more of rain in 24 hours over a 200-square mile area centered just northwest of Arlington. The water would surge through storm sewers, creeks and tributaries of the Trinity, course down the river channel, rise into the 1,700-foot floodway between the levees next to downtown Dallas, and spill over the 28-foot-high clay and earthen walls that keep the city dry.

"We could try to reinforce a section of the levee if the water were near the top in one spot," said Ron Shindoll, who oversees levee maintenance for Dallas. "But if there's a massive overflow of the levees, there's nothing to do but get out of its way."

Once the water started to cascade over the levees, erosion could quickly dig gullies into the huge earthen walls, and water would stream into downtown.

The extensive network of tunnels under the city's most prominent skyscrapers would be inundated, destroying businesses and utility lines. The water would shut down the pumps that force rainwater from the city streets back into the river.

The topography of the city is such that, somewhat like New Orleans, a downtown bowl would fill up as far east as City Hall. The flooding would extend northwest along the Interstate 35E corridor, putting Industrial Boulevard and Irving Boulevard under water, and marooning American Airlines Center, the Victory development, the Wyndham Anatole and Parkland Memorial Hospital.

Flooding would extend south of downtown into the Lamar Street area and the Rochester Park neighborhood. West of the Trinity, schools and neighborhoods north of I-30 in West Dallas would be inundated. Some neighborhoods in north Oak Cliff close to the river also would be flooded.

The flooding would compromise the Central Wastewater Treatment Plant near Cadillac Heights, allowing untreated sewage to escape into the floodwaters.

Such a nightmarish scenario may sound farfetched. And in fact, it might never happen. But given the right conditions, it could play out with the next Katrina- or Rita-like storm.

"A lot of things have to come together, but storm conditions like this happen fairly frequently in the country," said David Wilson, a hydrologic engineer for the U.S. Army Corps of Engineers in the Fort Worth district, which includes Dallas.

Craig Loftin, another hydrologic engineer with the corps in Fort Worth, said: "It's not a fairy-tale scenario. It's plausible."

Tropical storms moving north have produced some of the worst flooding in Texas history. In 1978, for instance, 32 inches of rain fell over 24 hours around Albany, Texas – about 150 miles west of Dallas. The remnant of Hurricane Rita is expected to drop up to 15 inches on East Texas in the next few days.

The Corps of Engineers, which improved the levees in the 1950s before turning them over to the cities of Dallas and Irving to maintain, inspects the levee system once a year. Recent surveys reported that the system is in "excellent" condition.

"We feel the system works very well," said Gene Rice, project manager for the corps. "We're not worried about it failing."

But as Katrina has proved, dire predictions can come true. In a 1987 New Yorker article on the corps' Louisiana levee and channel system, Fred Bayley, then the chief engineer for the Lower Mississippi Valley Division, told John McPhee: "Anything can fail. ... I never approach anything we do with the idea that it can't fail. That is sticking your head in the sand."

Changing elements

If the perfect storm did hit, the flooding would seem biblical. Decades ago, the levees would have been topped by runoff from a storm that dumped 15 inches of rain in 24 hours. Today, a lesser storm – one that dumps only 11 inches in that period – would be able to top the levees.

The levees haven't changed in that time, but the landscape has. In the 1950s, the soil would have absorbed some of the rainwater. But today, the water would roll off roofs, rush down streets and course across concrete parking lots, speeding the flow into the Trinity and dramatically increasing the volume of water such a storm would send between the levees.

Since the levees were finished in 1958, the population in the 10 counties of the Trinity watershed has grown over 200 percent, or 3.5 million people. Since 1990, the number of housing units in those counties has grown 25 percent.

"It's been a cumulative effect," said Mr. Ajemian, the Trinity River Floodway coordinator. "Mother Nature is not able to spread its wings like it used to."

That tremendous growth impedes the soil's ability to act like a sponge, sealing it over with a skin of hard, nonporous surfaces that force larger amounts of water into the Trinity and between the Dallas levees during major storms.

Officials say they would have a day, maybe two at most, to prepare for the levees to be breached.

Aside from the Cadillac Heights area, which remains completely unprotected, several spots considered weak chinks in Dallas' levee armor would demand the city's particular attention. One of them is the Oak Cliff side of the Houston Street Viaduct. The bridge was built in 1912, well before the levees. The roadway is 4 to 5 feet lower than the crest of the levee, providing a gap four lanes wide for water to sweep through. Mr. Shindoll would try to close the gap by dumping dirt on the road and building an earthen berm across.

Another weak spot is just below downtown, where the east levee curves away from the river and meets a concrete wall. The wall is 2 feet lower than the levee and has two gaps, each about 30 feet wide, to allow train tracks through. Officials assume they would have enough time to block these breaches with dirt already stored on site and reinforced by sandbags.

A day before the levees were expected to be breached, city emergency management officials would launch a massive evacuation of the city's downtown and close-in neighborhoods. Since people would not need to travel far to get out of harm's way, the exodus would probably not produce the nightmarish evacuation scenes witnessed last week on Houston highways as Hurricane Rita approached. But evacuating the heart of Dallas on short notice would pose its own major challenges.

"The key is to not sit and dither for 24 hours. Decisions about evacuating have to be made quickly," said Bill Eckert, Dallas County's emergency management coordinator.

The city's evacuation plan assumes most people would use their own cars. But consider the traffic jams during a normal rush hour out of Dallas and add the complication of having some regular routes blocked by flooding. The evacuation might also have to occur during continuing downpours, with rain pounding windshields and overwhelming wipers.

"There would be some significant confusion at first," said Kenny Shaw, director of the city's Office of Emergency Management.

Just as in New Orleans, many of the Dallas neighborhoods that would be most affected by a major flood are home to lower-income residents without cars. Fire and police officials would send trucks with loudspeakers into flood-prone areas, announcing the evacuation. People would be directed to the nearest bus stop. Dallas Area Rapid Transit buses would roll up and down the streets, ferrying residents to shelters.

Dallas County's 1,200 school buses also would be available, but again, speed would be vital. Some of those buses are stored along South Beckley Avenue, south of Interstate 30, just behind the west levee and in an area that would be flooded

Mr. Eckert said the county's list of bus drivers is longer than needed, in case some drivers fail to show up – a problem for New Orleans before Katrina.

Most of the city's disaster plans call for using a few large shelters, including the Convention Center and Reunion Arena. But if the levees were topped, those venues would be flooded. The city would have to open many small shelters away from the river, in recreation centers and public schools, stretching American Red Cross resources thin.

Lessons learned

Katrina's devastation and Dallas' effort to house thousands of New Orleans evacuees gave city officials valuable lessons on how to improve Dallas emergency plans.

One area that will require a significant second look is the plan to evacuate the elderly and handicapped from nursing homes and hospitals. Dozens of people died in such facilities after Katrina.

"We're going to upgrade our plans on how we deal with hospitals and nursing homes because they hadn't handled it very well down in New Orleans," Mr. Shaw said. "Evacuating those kinds of facilities would be a major, major undertaking."

The city also has learned that vendors the city would count on to quickly provide supplies would soon be overwhelmed.

"We'd have to be creative by relying on other volunteer organizations, neighboring cities and counties," said Jerry Martin, the city's emergency management specialist.

In addition, just as Katrina knocked out communications among New Orleans city officials, a flood would pose similar challenges for Dallas. Mr. Shaw said the city will have to look at investing more in satellite telephones and similar equipment to help bridge the likely communications gap.

The flooding would create another hurdle for the city's disaster response. Normally, during an emergency, officials meet two floors below ground in City Hall and open the emergency command center, which has computers, radios and city wall maps.

But in a levee breach, the underground floors of City Hall, which also house the city's 911 operation, would probably be flooded. The backup location, a training center on Dolphin Road, would also be in the flood area. Officials would probably have to retreat to a second backup location, the Centennial Building in Fair Park.

Because the city's pump stations are behind the levees and about 25 to 28 feet below the levee crests, they would soon be put out of commission if the floodwaters topped the levees. Rain falling in Dallas would back up in storm sewers, burst manholes and swamp the streets.

With low-lying train tracks in the flood zone, railroad cars transporting dangerous chemicals could get knocked over, and – as in New Orleans – submerged cars, trucks and storage tanks in older gas stations could leech oil into the water.

South of downtown, the city's wastewater treatment plant, which serves about 70 percent of Dallas, could easily be put out of service, spewing raw sewage into the floodwaters.

Hydrologists with the Army Corps of Engineers say that once water got over the levees, downtown would act like a closed system, with no place for the water to flow out.

With the pumps inoperable, officials might have to create several large holes in the levees to help get water flowing out of the city and back into the river.

It would take up to a month for the Trinity to retreat back into its channel.

There's another worry. The levees aren't the only structures protecting the city. North and west of the city, a series of large lakes – Joe Pool, Benbrook, Grapevine, Ray Roberts, Lewisville and Lavon – help capture and control rainfall runoff to the Trinity.

Corps officials say they regularly inspect the dams that regulate the flow from those lakes, and security at the dams has been tightened since the Sept. 11 terrorist attacks.

But should one of those dams break, the released water would overwhelm Dallas.

"Lewisville by itself, if breeched, could send enough water to overtop the Dallas levees," said Mr. Wilson of the corps.

Exposed to danger

Juanita Alfaro is painfully familiar with the wrath of an engorged Trinity River. For the past 37 years, she has lived in Cadillac Heights, a community that lies just beyond the end of the west levee. When the rest of Dallas is dry, Cadillac Heights often floods.

Ms. Alfaro spent years picking cotton and cherries, sewing in a textile plant and cooking in a country club restaurant. Several decades ago, she bought her modest one-story house, built on the corner of Pontiac Avenue and Cadillac Drive in 1920.

During a 1990 flood, the largest since construction of the levees began in the late 1920s, the Trinity invaded Ms. Alfaro's neighborhood.

The water lapped at the base of her windows 4 feet off the ground and swept in. She had evacuated the night before.

When she returned, she discovered that the water had ruined her furniture and plumbing and electric systems, and killed her plants. She had no flood insurance – too expensive. The city helped with money for repairs. She did what she could, bringing the salvageable furniture outside to dry in the sun and calling friends for help.

Despite the flooding, she didn't want to move. "I know the neighbors here. I wouldn't know anybody if I moved somewhere else," she said.

A $140 million project is intended to improve the lower Dallas levee system. includes an extension to protect Cadillac Heights. In addition, under the plan, the city is buying the homes of some of Ms. Alfaro's neighbors

The Dallas Floodway Extension Project is multifaceted. Plans drawn up by the Corps of Engineers and the city call for extending the existing west levee south to protect Cadillac Heights and extending the east levee south to protect the Lamar Street area, hooking it up with the levee the city built around Rochester Park in the early 1990s, after memorable flooding in 1989, 1990 and 1991.

In addition, to reduce the damming effect of the Great Trinity Forest, in the river's floodplain south of downtown, the city will remove a 600-foot-wide swath of trees to create a series of wetlands and help the floodplain handle more water.

The first of the wetlands, begun a year ago, was just completed east of Interstate 45. The Corps of Engineers has awarded a contract to build more wetlands over 107 acres farther south of I-45.

A separate but related venture, the Trinity River Corridor Project, includes $200 million in flood protection and recreation improvements, such as raising the existing levees by 2 feet and adding a chain of lakes in the floodplain just west of downtown.No money has yet been secured from the federal government for the flood protection portion of the Trinity corridor project, which has not yet reached the design phase.

Since 2001, the corps has received $43 million in federal money for the Floodway Extension Project. But congressional budget committees will probably trim its $30 million request for 2006 by more than half.In addition, about $4 million that had already been earmarked for the Floodway Extension Project has been redirected to New Orleans in Katrina's aftermath.

The entire array of improvements, barring delays, could be finished by 2014.

But Dallas officials worry that the huge costs of rebuilding New Orleans might suck away money for other projects.

"We have an ongoing challenge to get budget support for corps projects," said Mr. Ajemian, the Trinity River Floodway coordinator. "Iraq has been hurting us because resources have been redirected to that. And now we have New Orleans. The money has to come from somewhere. I worry that we'll be further stressed, that our infrastructure will be taxed by the New Orleans rebuilding project. I have no idea what New Orleans will do to us."

[wxmann_91]

Yikes!

I once lived there and I certainly don't want to see that happen. Dallas is such a great place, it would be such a shame to have that happen.

[soney]

Wow, thanks for posting that. I lived in the Dallas are for 12 years and actually worked at Parkland Hospital for 4 of those years so I very definitely know all of the areas they are talking about. Makes you wonder what they're going to do when their Level One Trauma Center is "marooned" by floodwaters?

Interesting that in all the time I worked and lived there, no one really talked about the threat from the Trinity.