St. Louis advances $565m River Des Peres CSO storage tunnel with new design and land funding

St. Louis advances $565m River Des Peres CSO storage tunnel with new design and land fundingThe Metropolitan St. Louis Sewer District has greenlit a combined $14.5 million for design amendments and property acquisition as it prepares to construct a massive 18-foot diameter deep storage tunnel to comply with its consent decree.

The Board of Trustees approved an $8.5 million design contract amendment with Jacobs Engineering Group for the Upper River Des Peres and River Des Peres Tributaries Storage Tunnel.

An additional $6 million was appropriated for aggressive property acquisition, demolition, and easements required to accommodate the future wet weather storage facility.

The planned six-mile tunnel will provide 58 million gallons of storage to reduce combined sewer overflows, with construction anticipated to begin in FY2032.

The board also approved $1.1 million for program management and $125,000 for dewatering pump station site preparation design.

At its July 9, 2026 meeting, the Metropolitan St. Louis Sewer District (MSD) Board of Trustees authorized significant funding packages to advance the Upper River Des Peres and River Des Peres Tributaries Storage Tunnel, a cornerstone of the utility's consent decree compliance strategy. The board approved an $8.5 million supplemental appropriation to amend an existing design contract with Jacobs Engineering Group. The funding covers ongoing design activities for the massive six-mile, 18-foot diameter CSO storage tunnel, which is projected to cost $565 million to construct. The infrastructure will provide 58 million gallons of deep tunnel storage to capture and hold combined sewage during wet weather events. The newly approved design funds include over $1 million in contingencies for final odor control design, surge and transient analysis model runs, additional geotechnical borings, and public relations. In tandem with the design progress, the board appropriated $6 million from the Sanitary Replacement Fund to initiate property acquisition. This authorization empowers MSD staff to negotiate buyouts, secure easements, and perform necessary demolitions in the project corridor—which spans municipalities including University City, Richmond Heights, Maplewood, and St. Louis—without requiring further board approval for individual parcels. A real property acquisition consultant will manage the process in accordance with federal relocation regulations. The Upper River Des Peres tunnel is a major component of the overarching Lower & Middle RDP CSO Controls System Improvements program, which carries a total preliminary construction estimate exceeding $1.5 billion. Jacobs Engineering serves as the watershed consultant for this comprehensive multi-year initiative, with total program design costs estimated to range between $90 million and $110 million. To support the broader watershed effort, trustees also approved a $1.1 million appropriation for Jacobs to continue program management, coordination, and modeling support for FY2027. Furthermore, the board greenlit $125,000 for the design of a dewatering pump station site preparation package specifically tied to the upcoming storage tunnel. Construction on the Upper River Des Peres deep tunnel system is anticipated to commence in FY2032, with capital costs expected to be funded by bond proceeds.