Johnson County cut the ribbon to celebrate the completion of the Tomahawk Creek Wastewater Treatment Facility (WWTF) today. Located at 10701 Lee Boulevard, Leawood, Kansas, in Johnson County, the Tomahawk Creek WWTF serves about 150,000 residents.

The facility is one of six major Johnson County Wastewater treatment facilities serving approximately one-half million residents. It began operation in 1955 and has undergone numerous expansions and upgrades over the years.

The most recent $270 million expansion is approximately 30 percent greater than its previous footprint. Essentially with this expansion the Tomahawk Creek Wastewater Treatment Facility is a completely new facility with more than 30 new structures, more than 130 installed pumps, 50,000 cubic yards of concrete, more than nine miles of underground utilities, and 792 deep foundation drilled shafts.

“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 latest expansion and upgrade of the Tomahawk Creek WWTF began in 2018 and was completed on schedule and on budget. The updated facility will improve water quality while providing cost-effective long-term treatment solutions for Johnson County customers. It will be able to treat wet and dry weather flows from 19 million gallons per day (MGD) to 172 MGD.

“The expansion and upgrade of the Tomahawk Creek WWTF is the largest project ever undertaken by Johnson County,” said Susan Pekarek, general manager of Johnson County Wastewater. “In addition to addressing environmental and water quality requirements, population growth in the area, and the need to replace and upgrade technologies in aging facilities, the project also was part of an economic decision to treat all flow locally.”

The Tomahawk Creek WWTF was a joint project of Johnson County Wastewater, McCarthy Building Companies-Kansas City, Black & Veatch Corporation 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.

“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.

During much of the construction, flow received at facility had been diverted to Kansas City, MO for treatment. The flows started to return to the site during the commissioning phase which began in August 2021. In January/February of 2022 the facility became fully operational.

“The design of the facility focused on cost-effective and reliable process solutions to minimize the power and chemicals required for treatment and deliver a long-term sustainable solution for the County,” said Derek Cambridge, associate vice president, Black & Veatch Corporation.

“The JCW Tomahawk Creek Wastewater Treatment Facility Upgrade is the ideal example of collaborative delivery. From regulatory negotiations and financial planning, through design, construction, commissioning, and inter-agency cooperation, highly positive outcomes were realized at every step – resulting in a showcase project for JCW’s customers and our community. HDR was honored to be a part of this team,” said Mike Kalis, project principal for HDR.