Flood Control for the Trinity River
The warm, optimistic glow cast by the city of Dallas’ $2.5- to $3-billion, comprehensive Trinity River Corridor project is partially shadowed by the findings of Periodic Inspection No. 9.
The ninth, five-year-cycled U.S. Army Corps of Engineers levee inspection in 2009 left Dallas with a failed rating, loss of levee certification, exclusion from Federal Emergency Management Agency flood plain maps, more than $8.4 million in operation and maintenance repairs, a $25.5-million contract award for a thorough, third-party levee assessment, and concern over whether any of those short-term funds will apply to the long-term federally certified flood control program.
“The city of Dallas is preparing itself to spend between $800 million and $1 billion to make changes to meet 100-year levels of protection that will be subsumed by the 800-year levels authorized by the federal government in the visionary Trinity River Corridor project,” says Rob Vining, vice president and national leader of the civil works practice, HNTB Federal Services Corp., Kansas City, Mo. The city of Dallas awarded HNTB a $25.5-million contract June 15, 2009 to assess levees, and help achieve a significant rating so the city didn’t lose Stafford Act coverage as of April 1, 2010.
“That means that if there is a flood event, the corps will come in and flood fight at no cost to the community, and any damage done as a result of a flood will be repaired,” Vining says. HNTB is also working with the city, the corps and FEMA on ensuring that Dallas remediates whatever is necessary to meet FEMA 100-year standards by March 2011, so it won’t be removed from the new flood maps.
“What we’re very concerned about is that those behind the levee who have never paid insurance before will have to,” says Liz Fernandez, assistant director, Trinity Watershed Management Department, city of Dallas. “We are worried about how that will affect new development and future growth.”
The assessment, remediations and additional measures to bring the Dallas system to 800-year levels are authorized under the 2007 Water Resources Development Act and are rolled into the corridor project. However, the feasibility study, which is not fully funded, is not scheduled for completion until 2013. Construction won’t likely begin for another decade, Vining says. “The city can’t wait 10 years.” HNTB completed its assessment in April and the city plans to begin letting contracts by the end of 2010. “There are a lot of seepage and stability concerns, but all fixable,” Vining says. Relief-well installation and sheet pile cutoff walls (that stop seepage through underlying sand strata) are likely remedies.
Historically, the corps has conducted an annual, visual inspection of levees and a more in-depth “periodic” analysis every five years. Dallas has received good reports until its first periodic inspection after Hurricane Katrina hit New Orleans in 2005. “We’re one of the first major levee systems to receive this inspection, so I think everybody is kind of looking toward us to see what we are doing,” Fernandez says.
The inspection process has become more rigorous and will be enforced more consistently since Katrina, says Eric Halpin, program manager for the corps’ national levee safety program. “We’ve gone from a program based on routine inspections to a more in-depth technical assessment and risk assessment of levee systems,” Halpin says. “We’ve put additional requirements and additional funding on being able to tell the stories of our levees. He adds, “In Dallas as in a lot of areas around the country, the deficiencies we are finding aren’t new, but how we bundle findings and characterize that system due to deficiencies has changed.”
Fernandez says the city had been getting good and excellent scores from the corps until after Katrina. With Periodic Inspection No. 9, Dallas was found to have 198 operations and maintenance issues that needed to be addressed, including erosion, rusted flap gates, bridge piers that pierce levees and streamlining of utilities crossings.
By February, Dallas had completed about 70% of the 198 projects. “The money for operation and maintenance fixes came out of the general fund for O&M for the floodway,” says Rebecca Rasor, managing director of the Trinity River Corridor Project. “Funding for fiscal year 2009-2010 was increased by $8.4 million to address those items that they deemed deficient. For the bigger ticket items we’re going to have to tap into bond funds.”
The city of Dallas is hoping that the corps will eventually reimburse it for some of the work because it designed the original levees it is now deeming deficient. But the corps says it is a local responsibility. “Right or wrong, this is how Congress directed the corps to approach levees,” Halpin says. “The corps designs and constructs certain projects, to a certain level. The local authority takes it with the agreement that they operate, maintain, rehabilitate and replace if necessary in exchange for this local benefit.”