Johnson County Tomahawk Creek Wastewater
Johnson County, Kansas
Better Water/Environment
Presented by: McCarthy Building Cos.
Region: ENR Midwest
Owner: Johnson County Wastewater
Main design company: Black & Veatch/HDR
General contractor: McCarthy Building Cos.
Civil engineer: Black & Veatch/HDR
Structural engineer: Black & Veatch/HDR
MEP Engineer: Black & Veatch/HDR
Subcontractors: McCarthy/Castle JV; RS Warranty; Ambassador Steel; Ham
Population growth, aging infrastructure and tighter effluent limits spurred the need for a large-scale expansion of the Tomahawk Creek Wastewater Treatment Plant, which began operating in 1955 in Johnson County, Kan. The $268 million expansion included the construction of 30 new structures, more than 130 pumps installed, 50,000 cubic yards of concrete, nine miles of underground utilities and 792 deep foundation drilled shafts. It is the largest infrastructure project ever undertaken in the county, increasing the facility’s footprint by approximately 30%.
In addition, the project nearly tripled the facility’s average treatment capacity to 19 MGD during dry weather and to 172 MGD during wet weather. Construction could not proceed without diverting the flow, which presented a challenge. The team devised a strategy to temporarily divert all flow to neighboring Kansas City, Missouri, which eliminated extensive maintenance from the plant’s operations and accelerated construction by an estimated 1.5 to 2 years.
“Ultimately, diverting the flow helped the simultaneous demolition of the old plant and construction of the new plant,” says BJ Peterson, vice president of operations for McCarthy Building Cos.’ national water team. “Despite other challenges such as the pandemic, the wettest year on record, and on-site craft and trade peaking at over 400, the team finished ahead of schedule and under budget, saving costs through a early flow treatment in new treatment facilities”.
