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Mill Creek and Peaks Branch watersheds in Dallas were developed in the 1930s. The open channels that were Mill Creek and Peaks Branch became horseshoe culverts and large box culverts that were when constructed roughly a 5-year storm frequency capacity. A similar situation occurred in the State Thomas area immediately northeast of downtown Dallas. With redevelopment and increased imperviousness, storm drain capacities have diminished to closer to a 2-year frequency. Drainage relief for the Mill Creek / Peaks Branch / State Thomas areas will be accomplished through the design and construction of a single 30-foot diameter, 27,000-foot long drainage relief tunnel valued at $320 million. The deep tunnel will bisect the watersheds, and provide 100-year, or near 100-year, capacity in the existing downstream storm drains. The tunnel will be mined in the Austin Chalk formation between 100 and 150 feet below the surface and will outfall to White Rock Creek. The major elements of the project include:
- Surface inlets and near-surface storm drains to intercept and convey overland flow exceeding the capacity of the existing storm drains to new inlet structures,
- Five large inlet structures that will receive stormwater from the existing storm drains and from the new inlets intercepting surface overflows,
- Five drop shafts varying in size from 12 feet to 25 feet in diameter, connecting the inlet structures to the deep tunnel,
- A 40-foot diameter outfall shaft, and
- A 30,000-gpm dewatering station
Todd Woodson served as the project manager for Mill Creek & Peaks Branch Tunnel in Dallas. Todd has 18 years of experience in design, management, and construction of heavy-civil projects. His design expertise includes airfield, military construction, land development, transportation and drainage-relief projects. He has managed such projects as the DFW International Airport, Terminal D, Perimeter Apron Paving Project in Irving; the Kilby Center East at Texas Instruments North Central Expressway location in Dallas and various assignments for USACE and AAFES at Fort Bliss, Texas, Fort Polk, Louisiana, Redstone Arsenal in Alabama and Shaw Air Force Base in South Carolina. Todd received his bachelor of science in civil engineering from Texas A&M University.
Lesley Schwalje is a project manager with HNTB Corporation with nearly 15 years of consulting experience in Kansas City and Dallas. Her experience includes transportation / roadway studies and design, as well as levee assessment and design. HNTB brought Lesley to Dallas in 2009 to manage the City of Dallas’ Levee Remediation Project. She has since also taken over management of the City of Dallas Program Management Contract which includes oversight of the Mill Creek/Peaks Branch Drainage Relief Tunnel as well as multiple new pump stations.
Lesley has a Bachelor of Science degree in Civil Engineering from Iowa State University and is licensed professional engineer in the states of Kansas and Texas. Prior to her work with the City of Dallas, she worked on multiple levee systems in the Louisiana Gulf Coast Region as well as various highway/roadway projects throughout Kansas and Missouri.