Johnson County Wastewater clears CMAR route for $200m Middle Basin solids upgrade

Johnson County Wastewater clears CMAR route for $200m Middle Basin solids upgradeJohnson County commissioners unanimously authorised construction management at risk delivery for a major digester and dewatering project at the Douglas L. Smith Middle Basin Wastewater Treatment Facility. The utility expects the project to cost $150 million-$200 million and to require roughly two years of design before a construction funding request in 2029.

The board approved Resolution 26-035 unanimously, allowing CMAR procurement for the Middle Basin Digester and Solids Improvements Project.

Johnson County Wastewater estimates the project at $150 million-$200 million, before detailed design.

Works will add digestion capacity, rehabilitate existing digesters and replace dewatering equipment at the end of its useful life.

The facility must maintain treatment operations during construction; new digestion capacity is needed before an existing digester can be taken out of service.

The utility cited $41 million in design-stage savings identified through CMAR value engineering on its Tomahawk project.

Johnson County Wastewater (JCW) has won unanimous approval to use construction management at risk (CMAR) for a $150 million-$200 million overhaul of solids handling at the Douglas L. Smith Middle Basin Wastewater Treatment Facility in Overland Park, Kansas. The board’s 8 October decision authorises the collaborative procurement route for the Digester and Solids Improvements Project, identified as IMB1-Contract 40. JCW said the scheme is included in its 25-year integrated plan and five-year capital improvement programme. The Middle Basin facility is located near College Boulevard and US 69. JCW said its scope will centre on digestion assets, which stabilise solids for land application, and on dewatering equipment that removes water from digested material before that application. The utility has no excess digestion capacity, according to Tammy Lorenzen, and has therefore been unable to take an existing digester out of service for renewal work. The project will add capacity before rehabilitation of existing digesters proceeds. It will also replace dewatering equipment that has reached the end of its useful life. Maintaining treatment operations during construction is a central project constraint. Lorenzen told commissioners that the need to build capacity before taking down a digester, coupled with limited ability to inspect the digesters to date, means there will be undefined scope at the beginning of the project. Commissioner Jeff Meyers asked about the consequences of a digester failure. Lorenzen said JCW could assess whether capacity was available at the Tomahawk facility, where digestion is also performed. Otherwise, the utility could need to send material to Waste Management, subject to obtaining the ability to deliver additional sludge and at increased cost. She said JCW monitors critical assets through its asset-management programme and has contingency options for dewatering-equipment failures, including rehabilitation or an emergency replacement contract. JCW selected CMAR because the delivery method brings the construction manager into the design phase while the designer develops the project. The contractor will develop a cost model in parallel, while both parties can identify risks, consider measures to contain them and undertake value engineering. The approach will involve separate contracts for the designer and construction manager. Lorenzen said the utility has used CMAR on three previous projects and considers it suitable for complex work requiring continued operations during construction. She cited $41 million in savings identified through design-stage value engineering on JCW’s Tomahawk project. JCW also held informal market meetings and reported strong contractor interest in a CMAR project of this scale. The approval only authorises the delivery method. JCW expects to return in early 2027 for award of a design contract, followed by selection of the construction manager at risk. It anticipates around two years of design and plans to seek construction funding authority and award the construction contract in 2029. The board approved Resolution 26-035 by a 7-0 vote following a public hearing in which no comments were made.