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McCarthy Building Companies Complete Construction for Tomahawk Creek Wastewater Treatment Facility

LEAWOOD, KS — McCarthy Building Companies has completed construction at Tomahawk Creek Wastewater Treatment Facility (WWTF) in Leawood, Kansas, one of the world’s largest Aqua-Aerobic disk filtration system installations for dual-use filtration. Begun in 2018, the project was completed on schedule and on budget.

Located in Johnson County, Kansas (suburban Kansas City), the $270-million expansion is approximately 30 percent greater than its previous footprint and represents a complete overhaul of the existing facility, which began operation in 1955 with numerous expansions and upgrades over the years.

“Making this type of investment in the infrastructure of Johnson County is crucial,” said Ed Eilert, Chairman of the Johnson County Board of County Commissioners. “Through this investment and the expertise of everyone who worked on the project, Johnson County Wastewater residents served by Tomahawk Creek don’t have to think about wastewater treatment, they can rest assured that this important service is being taken care of by a facility that will meet future water quality regulations and control costs.”

The current expansion includes more than 30 new structures, more than 130 installed pumps, three tower cranes, 50,000 cubic yards of concrete, more than nine miles of underground utilities, and 792 deep foundation drilled shafts.

The Tomahawk Creek WWTF was a joint project of Johnson County Wastewater, McCarthy Building Companies-Kansas City, Black & Veatch, and HDR. Due to the complexity and tight schedule, Johnson County chose to use the collaborative delivery method of Construction Manager at Risk (CMAR) with McCarthy serving as the construction manager. In addition, McCarthy’s fully owned subsidiary, Castle Contracting, provided concrete services, making the project’s concrete all self-performed.

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“Building water infrastructure projects like the Tomahawk Creek WWTF are not only economic drivers for local communities where we live and work, but they also provide sustainable resources that will greatly benefit future generations,” said BJ Peterson, Vice President, Operations, McCarthy Building Companies in Kansas City.

The Tomahawk Creek WWTF serves about 150,000 residents and is one of five wastewater treatment facilities serving approximately one-half million residents in the region. In addition to improving water quality while providing cost-effective long-term treatment solutions for Johnson County customers, the new facility has the capacity to treat wet and dry weather flows from 19 million gallons per day (MGD) to 172 MGD.

During much of the construction, flow received at the facility had been diverted to Kansas City, Missouri, for treatment. Following the commissioning phase conducted from September 2021 through March 2022, all flows have been treated through the plant.

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