A River Runs Through It
By fall, kayakers will enjoy the new waterfalls and whitewater in the Trinity River as part of the recreation portion of the $2.5- to $3-billion city of Dallas Trinity River Corridor project that is 20 mi long and encompasses 10,000 acres. The comprehensive plan includes projects for flood control, transportation, recreation, environmental restoration and economic development.
Ark Contracting Services, Kennedale, will begin this month a $3.7-million contract to build concrete “speed bumps,” about 150 ft wide and about 250 ft apart in the river that will create a 3-ft drop and wave action that should thrill kayakers, says Rebecca Rasor, managing director of the Trinity River Corridor project for the city of Dallas.
Contracts for other recreational components of the project – including a soccer complex and parks – will be let later this year. The Trinity River Audubon Center, a 20,000-sq-ft nature/education facility in the 6,000-acre Great Trinity Forest – was completed more than a year ago. Some water containment/wetland areas are currently under construction. The $93-million Margaret Hunt Hill Bridge is scheduled for completion March 2011. Two other proposed bridges–the IH-30 and Sylvan Avenue replacements–have partial funding. The IH-30 design is partially complete, and Sylvan is awaiting environmental clearance, says Tim Nesbit, Texas Dept. of Transportation spokesperson. The IH-35 bridge currently has no funding and is not under design, Nesbit says.
The private Trinity Trust Foundation raised $40 million for Trinity River Corridor projects, Rasor says. The city has allocated $84 million for portions of the project. The Margaret Hunt Hill Bridge, designed by Santiago Calatrava, Spain, received $28 million from a bond program, $10 million from private donors, and FHWA funds.
However, most elements of the comprehensive program are still awaiting funding, environmental impact statements, and a U.S. Army Corps of Engineers feasibility study that is scheduled for completion 2013. Flood control, sluggish funding and implementation of civil works are primary factors in the overall program’s success.
The public supported the Trinity River Corridor with a 1998 bond package, but parts of the project have origins in the 1920s when the city’s first levees were built, Rasor says. “The Dallas Floodway Extension was authorized by Congress in 1965, went before voters in the 1970s and was defeated,” Rasor says. “In 1989, 1990 and 1991 we had some of the worst flooding the Trinity River has ever seen.” That prompted the formation of the Trinity River Corridor citizens committee, which created the five-part comprehensive plan.
The other four components–their approval, design and funding–are all contingent upon the flood control aspects of the project and corps approval.
In 1996 when Dallas wanted to embark on the Trinity River Corridor project, it asked the corps to conduct a feasibility study to determine if the final, proposed project could handle the additional water runoff from upstream development and still afford the city’s desired, 800-year levels of flood protection. The Dallas floodway and floodway extension study has become an “authorized project to raise the existing levees by 2 ft and construct the balance vision plan that includes recreation features, improvements to pump stations and sump areas outside the levees,” says Kevin Craig, corps project manager. The study, scheduled for completion in 2013, still has not been fully funded, and construction money isn’t even on the horizon, Craig says. “The $38-million study is cost shared, and $23 million has been funded by the city. We are looking for federal appropriations over the next several years for the remainder.”
Design for the Dallas floodway began in 2008, but won’t be complete until the corps delivers its environmental assessment later this year. The corps project area includes about 22 mi of river levees (11 on either side), interior drainage, pump stations, sump areas, lakes and river meanders and new levees (the extension) for about 2.5 mi on one side and 3 mi on the other side of the river. “There is a chain of wetlands, seven cells that act as flood conveyance during flood events and wetland cells during non-flood times that are nourished by discharge of wastewater treatment,” Craig says. The cells are huge, excavated areas, which will require moving a lot of dirt.
In March the corps was about 95% complete on construction of the lower chain of wetlands and anticipated having designs and specifications advanced enough to construct the upper portion of cells and “significant portions” of one levee by fiscal year 2011, Craig says.
The corps also has to evaluate all proposed bridge crossings and make sure their construction and operation are compatible with flood protections. “When we started the feasibility study, piers of the Margaret Hunt Hill Bridge had already been poured within the floodway system, so we had to ensure that any impacts were handled during construction,” Craig says.
TxDOT began construction of the bridge n 2007. “We have gone to special construction techniques to make sure we don’t damage the levees in any way,” says Tracey Friggle, TxDOT director of construction. “We’re careful about drill shafts, drilling and pouring one at a time and under the corps’ supervision, so they can see the soil coming out, particularly at the slope of the levee.” The Margaret Hunt Hill Bridge piers go through the existing floodway levee, so TxDOT performed additional geotechnical analysis and added design features to address seepage and slope stability concerns.
The holistic, comprehensive approach is a unique aspect to the Trinity River Corridor project, Craig says. “That’s different and a better approach than making incremental decisions and rushed decisions that could affect the ability of some components to be built.”