Public Works Committee backs updated stormwater quality plan, outlines multi-year projects

The Monona Public Works Committee voted to recommend that City Council accept a multi-year update to the city’s stormwater quality plan, a package staff said combines older plans, recent SLAM model updates and project scoping required by state DNR adaptive-management rules.

Public Works Project Manager Brad Bruin summarized the city’s recent work: the 2014 plan had not been comprehensively updated; the city installed six underground treatment devices between 2013 and 2016 and more recently completed the Stonebridge Park device in 2021. Staff used updated SLAM (Source Loading and Management) modeling and a 2018 technical memo to prioritize future capital projects and to reduce the city’s adaptive-management obligations for total phosphorus.

Staff said once the Kelly Place stormwater improvement is constructed the model shows reach 64 (the northern half of the city) will meet total phosphorus reduction requirements; reach 65 still needs additional phosphorus reductions and reach 66 currently meets both total phosphorus and total suspended solids requirements. Priority near-term projects identified for the permit term include the Kelly Place facility (an underground concrete treatment vault), the Gishalt (Kushal) basin improvements (dredging/rehabilitation of an above-ground detention basin that serves an industrial area), and potential underground devices at Arrowhead Park or Frostwoods Beach Park.

The presentation also covered program-level items: updates to the city’s procedural manual, a pollution-prevention plan for the public works garage (a DNR audit requirement), and the city’s use of credits and trading (the city currently participates in adaptive-management purchases). Committee members asked about the trade-off between underground concrete vaults and surface green infrastructure; staff said vaults are favored for their space efficiency, lower long-term maintenance burden on city crews and higher predictable pollutant removal for phosphorus and TSS. Staff acknowledged trade-offs including reduced public green space and larger capital cost per project.

Committee members asked whether meeting the state TMDL (total maximum daily load) remains possible; staff said meeting TMDL without trading would require substantially higher infrastructure investment and that trading purchases currently reduce the city’s annual compliance cost (staff estimated current adaptive-management payments near $19,000–$25,000 depending on credits). Staff estimated the city would pursue an infrastructural project roughly once per five-year permit term, with many candidate projects lined up for future capital budgets.

After discussion, a committee member moved to recommend council acceptance of the stormwater quality plan update; the motion was seconded and approved by voice vote. Staff said the DNR grant that funded the plan update requires public presentation and council acceptance before final reporting to the state.

Ending: The committee recommended council accept the plan update and directed staff to carry the recommended next steps — project design and grant applications — into the capital program and upcoming budget work.