Over a period of 18 months, the Lower Colorado River Authority will remove and replace all nine floodgates at its Tom Miller Dam to ensure continued safe, reliable operation of the structure.
Tom Miller Dam in Austin, Texas, creates Lake Austin. Its powerhouse has a capacity of 17 MW.
The floodgates were installed during construction of the dam in the late 1930s. “The dam is in excellent condition, but it’s almost 89 years old,” said John Hofmann, LCRA executive vice president of water. “This project will replace the aging floodgates with new, custom-built floodgates that will help ensure the dam will continue to perform reliably and safely for generations to come.”
In 2007, a consulting engineering firm performed a detailed inspection of the dam and recommended that some steel members be replaced or reinforced no later than 2020 to meet the latest design standards. LCRA determined replacing the floodgates was the best option with the lowest safety risk, lowest environmental risk and least public inconvenience. LCRA determined rehabilitating the floodgates in place would have taken four to five years.
Tom Miller Dam has four large floodgates – 51 feet by 20 feet – and five smaller floodgates – 51 feet by 15 feet.
This work is expected to cost $9.9 million and is the “second extensive renovation of the dam since it was completed in 1940.” In 2005, LCRA “completed major structural improvements” as part of a dam modernization project.
LCRA will replace one floodgate at a time, and work on each will take about six weeks.
The project will involve the use of a large construction barge that will stay at the dam and a smaller shuttle barge that will ferry the new floodgates and other equipment to the dam. The new floodgates are being fabricated and partially assembled in Michigan, then shipped to Austin via truck.
Although Tom Miller Dam has nine floodgates, the most ever opened at any one time is five.
LCRA delivers electricity, manages the water supply and environment of the lower Colorado River basin, provides public recreation areas and supports community development. The company produces electricity from coal, natural gas and hydro facilities. It operates six dams with hydroelectric facilities, with a total capacity at these six plants of more than 295 MW.