Major dam rehab projects on the horizon
Things have certainly not slowed down this fall at the Brazos River Authority as staff embarks on large improvement projects for each of its three reservoirs.
Created by the Texas Legislature in 1929, the BRA is dedicated to maintaining the structural integrity of its dams and prolonging the life of these critical structures. Recently the Board of Directors unanimously approved the new fiscal year budget, which represents $69.7 million in total anticipated revenue and $69 million in operating expenses. BRA staff and engineers have eagerly begun working on capital improvement projects included in the budget, totaling roughly $47.1 million.
These projects will help ensure the BRA can continue to successfully manage its water resources within the basin.
The BRA water supply system includes 11 reservoirs scattered across the 42,000-square-mile river basin. The recently-approved projects will occur at the man-made reservoirs owned and operated by the BRA: Possum Kingdom Lake’s Morris Sheppard Dam, Lake Limestone’s Sterling C. Robertson Dam, and Lake Granbury’s DeCordova Bend Dam. The other eight are owned, operated, and maintained by the U.S. Army Corps of Engineers; however, the BRA does provide some of the funding for these reservoirs as well.
The big project for DeCordova Bend Dam is to address its low flow facilities. The BRA approved a contract with Gannett Fleming Inc. to perform engineering, construction oversight, and consultant services for the rehabilitation of the associated low flow gates.
The maintenance project’s schedule has not yet been defined, said Michael McClendon, BRA Upper Basin Regional Manager.
“The low flow is operational now, but not up to the operational flexibility that the repair project will address,” he said. “The operational flexibility to pass flows for environmental purposes and utilize the smaller gates as opposed to the larger tainter gates, for smaller releases is why the low flow gates are important.”
Further south, the Tainter gates will be replaced at Lake Limestone’s Sterling C. Robertson Dam, located on a tributary of the Brazos River, the Navasota River, in Limestone, Robertson and Leon counties. The engineering design for this project will be performed in fiscal year 2020 with the actual gate replacement occurring in subsequent years.
All five floodgates will be replaced one at a time on the dam that runs 8,395 feet and stands 72 feet tall. Originally built in 1978, replacement of the gates and other rehabilitation work will help ensure the structure’s longevity. The project comes on the heels of the decade-long complete gate replacement at Morris Shepperd Dam.
The biggest challenge to the project will be working with the size of the massive gates which will need to be transported across the water, said Reservoir Manager Davy Moore.
At the BRA’s oldest dam, Possum Kingdom Lake staff will work on a capital project focused on the spillway gates of Morris Sheppard Dam. The BRA’s Reservoir System Maintenance Unit – RSMU - is in the process of purchasing materials to fabricate, construct and install new side seal plates on each pier that supports the spillway gates. The plates provide a surface for the gates to seal against and prevent leakage of water when the gates are closed.
The staff is also working on a concrete assessment and service-life extension project for the dam. The project will identify, investigate, and improve elements of the dam critical to extending its life beyond its 100th birthday. Completed in 1941 with the aid of the Depression-era Works Progress Program, the Morris Sheppard Dam stretches 2,700 feet long and 190 feet high, or one-half mile long and 13 stories high.
The projects though are just a part of regular dam upkeep.
Upkeep is a daily job at all three dams.
“We have a crew located at Lake Granbury that performs daily, weekly, monthly, annual and five-year inspections,” said Connie Tucker, Lake Granbury Reservoir Manager. “The dam is their No. 1 priority. And maintenance is performed daily.”
Also, the annual and five-year inspections are overseen by the Texas Commission on Environmental Quality, she said.
“During the annual and five-year inspections, we hire an outside engineering firm to come in with a fine-tooth comb and look at everything, from the concrete to the gates, to the electronics,” Tucker said. “The firm then presents results and recommendations for us to implement.”
The Granbury dam is 50 years old, but in very good condition, she said.