Dallas flood relief tunnel 80% complete, final lining work underway underground
An underground flood control tunnel designed to ease stormwater surges in East Dallas is now about 80% finished, as reported by NBC-5. The 5-mile-long Mill Creek Drainage Relief Tunnel stretches from Uptown through Fair Park and is located 75 to 150 feet beneath the surface.
Major excavation began in 2019 and wrapped up in 2022, but work continues to install a 15-inch-thick concrete liner along the tunnel walls to create a smooth, finished surface for water flow. As of May 2025, just over 20% of that liner work is complete.
Completion of the tunnel is now targeted for March 2027—a delay city leaders attribute to setbacks in early excavation, including assembly and operation of the tunnel boring machine, NBC-5 reported.
Once operational, the tunnel is expected to significantly reduce flooding in neighborhoods surrounding the intake points, where runoff will be diverted underground more quickly during major rain events.
In addition to the core tunnel, future project phases will involve lateral line connections at six access shafts. The city is currently pursuing funding to move that next stage forward.
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