Feature Photo: A look below at the breakthrough of Big Tex at the Mill Creek Tunnel. Image: Halff Associates
Richardson (Dallas County) – The Mill Creek/Peaks Branch/State Thomas Drainage Relief Tunnel (Mill Creek Tunnel) reached an important milestone last month, when the tunnel boring machine (TBM) broke through the shaft wall to complete the excavation phase.
The large‑diameter TBM, nicknamed “Big Tex,” completed a 5-mile journey that included 2 miles of 37.5-foot-diameter excavation and 3 miles of 32.5-foot-diameter excavation. Big Tex was the largest hard-rock TBM in operation in the U.S. during the excavation phase.
Members of Halff’s Mill Creek Tunnel team pose for a photo on July 25 after the shaft wall excavation was completed.
Construction of the tunnel’s concrete liner will begin in the project’s next phase. Once complete, the Mill Creek Tunnel will include 2 miles of 35-foot-diameter tunnel and 3 miles of 30-foot-diameter tunnel.
Halff led the design effort for this $320 million drainage relief project, including the centerpiece Mill Creek Tunnel, which is being constructed at depths reaching 170 feet underground. Once completed, the project will provide flood protection during the 1-percent annual chance flood (or 100-year flood) for nearly 2,200 commercial and residential properties in East Dallas.
The project team includes the owner, City of Dallas, lead design firm Halff Associates, Inc., construction manager Black & Veatch and construction contractor Southland Mole JV.
Art Benavidez (Construction News Reporter, Central Texas) is a seasoned journalist with over 15-years of experience in writing breaking news and in-depth features at the local level. He honed his research and reporting skills in newspapers and magazines throughout South and West Texas along with expertise in crafting digital content as Managing Editor of New Image Marketing Research Corporation. Benevidez is a Texas native and graduate of UT-RGV.