Downtown Austin has suffered from severe flooding for years. When completed, the Waller Creek Tunnel will provide flood relief for much of the downtown area. The mile-long tunnel will run from Waterloo Park along Waller Creek to its outlet at Lady Bird Lake. It is 20 to 26 feet in diameter and has an average depth of 60 to 70 feet underground. The project’s sole shaft is located at 4th Street, and is 70 feet deep and 30 feet in diameter. It will eventually serve as an inlet structure. The tunnel is expected to cost $106 million.
Schnabel’s role in the project began during the bid phase, when we performed a complete project takeoff and check estimate for the eventual contract winner. After award, we designed the initial support for the work shaft and tail tunnel, two connection chambers, and the three diameters of the conveyance/storage tunnel. During design, there was particular concern about the arch capacity of the large connection chamber spans, which are over 60 feet in length, and the swell potential of the Eagle Ford shale present at the site. We also developed better support options that were accepted by the city.
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