Johnson County to consider up to $8.13 million payment to Kansas City for Dykes Branch interceptor upgrades; public hearing set

Johnson County wastewater staff at an April 3 agenda review presented a request to authorize funds, not to exceed $8,128,419, to reimburse the city of Kansas City, Missouri, for Johnson County’s portion of capacity improvements to the Dykes Branch interceptor. The board will conduct a public hearing on the item and formal action is scheduled for the April 10 meeting.

Aaron Witt, Johnson County wastewater, said portions of the county’s sewer system in Leawood and nearby areas flow across the state line into Kansas City, Missouri, and that peak wet-weather flows still travel via the Dykes Branch interceptor. He said Kansas City is required by the U.S. Environmental Protection Agency through a consent decree to increase capacity on the interceptor to relieve overloads during storm events. Johnson County participated in preliminary design and flow monitoring; hydraulic modeling and flow data indicated the county contributes about 85% of the line’s flow for the affected segment, and the county’s share of design, easement and construction costs is roughly $7.7 million.

Witt said the total project cost including design and construction is approximately $9,000,000.83 and Johnson County staff included a 5% contingency to arrive at the $8,128,419 authorization request; the county expects to reimburse Kansas City in 2026 after construction and final accounting. Funding for the county’s share has been included in the wastewater capital finance plan, Witt said; Kansas City managed bidding and will manage construction. Witt added the county’s parallel pump-station and force-main project is expected to transfer most normal daily flows to the county’s Tomahawk treatment facility and generate long-term savings, but peak wet-weather events will still route to the Dykes Branch interceptor until Kansas City’s enhancements are complete.

Commissioners asked whether the county would face ongoing costs. Witt said the county would continue to pay Kansas City for the volume it sends them, but the county’s pump-station and force-main work should capture about 90% of the volume currently routed across the line in normal conditions. Commissioners also asked whether inflow-and-infiltration (I&I) removal efforts would make the downstream project unnecessary; Witt said I&I removal reduces flows over time but would not eliminate the need for the immediate capacity work required by the consent decree. The item requires a public hearing and will remain on the April 10 action docket.