The Utilities Committee met 03/25/2025. The item that took up most of the committee meeting was an information update on the Northland – Bellaire flood study that is currently being conducted by Brown and Caldwell. This study was approved in November of 2024 in response to the catastrophic flooding residents in the area experienced after severe rainfall in July of 2024.
Public Works Deputy Director Pete Neuberger gave an overview of what they had already accomplished and what they planned to do moving forward. He would not commit to a deadline for when the study would be completed but said it was a safe bet that the study would be completed by the end of the year if not sooner. He said that Brown and Caldwell had been working diligently and quickly on it.
I’ve prepared a transcript of the discussion for download:
Deputy Director Neuberger went through the memo line by line reviewing the completed tasks, ongoing tasks, and future tasks and stopping for questions along the way.
COMPLETED TASKS
- Kickoff meeting held December 11, 2024.
- Reviewed location and description of July 2024 and historic flooding reports with DPW.
- Updated the previously developed system models to reflect current industry standard rainfall distributions and depths.
- Merged previously developed Northland model and Bellaire model into one combined model incorporating both watersheds.
- Performed field site visits to verify previously modeled existing conditions, including flow paths.
Alderperson Chris Croatt (District 14) asked if there had been any moments during this process in which they came across surprises or things they didn’t know. Deputy Director Neuberger said that Brown and Caldwell had developed the existing Northland study model, but a different consultant had developed the Bellaire study model. In creating a model for the entire Northland/Bellaire flood plain, Brown and Caldwell had really dug into the guts of the Bellaire model so that they could make sure that some of the assumptions built into that model were built into that model were consistent with their own standard approach. He said most of those differences had to do with the way some inlet capacities were being handled as well as some of the flow paths. There had not been anything super shocking about the approach the other consultant had taken and Brown and Caldwell let city staff have an opportunity to weigh in on how to resolve the differences between the models.
ONGOING TASKS
- Performing subwatershed-level inlet capacity calculations.
- Running sensitivity analyses for two different antecedent moisture conditions.
- Running sensitivity analyses for concept-level scenarios using 10-year and 100 year storm events to narrow down potential locations and types of practices for more detailed evaluation.
Deputy Director Neuberger spent some time explaining that they were running analysis based on two different baseline levels of moisture within the soil. The industry standard was to assume a relatively low baseline soil saturation level, but, given that the flooding in July of 2024 happen after the area was already fairly saturated, they were also conducting analysis on what would happen with a higher level of soil saturation.
Alderperson Croatt asked if they were looking at how rainfall impacted things at different times of the year. Deputy Director Neuberger said they were not but, essentially, running the model on two different soil saturation conditions accomplished the same thing. There tended to be more rain in the spring, so the higher saturation level model would apply to that. There tended to be less soil saturation in the summer, and the industry standard model would apply to that.
Alderperson Patrick Hayden asked if they were gauging the impact of development that was taking place outside of the Northland-Bellaire floodplain. He was specifically concerned that the grassland just north of 41 was going to be developed and converted into impervious surfaces soon. He wondered if that was being taken into account.
Deputy Director Neuberger said that the north end of the Northland-Bellaire floodplain stopped at the 41 freeway, and that was not an arbitrary decision. It was based on the direction the water flowed. The water north of 41 does not flow toward the Northland Avenue watershed. Instead it travels north and east along the Apple Creek corridor.
Director of Public Works Laura Jungwirth added that since 2004 Appleton has had a more stringent storm water ordinance that applies to new developments. She also noted that other municipalities she had worked in had certain watersheds that were listed as “areas of known flooding” which had more stringent requirements for peak flow control than other areas.
When asked if Appleton had such designations, Deputy Director Pete Neuberger said there was a phrase in the stormwater ordinance that pertained to “critical sites” that did allow the city to require more stringent rules to certain areas.
Alderperson Vered Meltzer (District 2) asked if the results of this study could result in those water ordinance requirements being adjusted. Deputy Director Neuberger thought it was possible that what they learned through this study might inform the city’s future approach to regulations throughout the city, not just in this area.
FUTURE TASKS
- Evaluate individual storage and conveyance alternative components and present initial findings to DPW for initial feedback.
- For highest ranked components, evaluate potential conflicts with other utilities and develop preliminary cost estimates.
- Develop WinSLAMM water quality models to identify potential stormwater pollution reduction measures that could be incorporated into the alternatives under consideration.
- Group most highly ranked individual alternative components into three combined alternatives and present to Utilities Committee with recommendations for approval.
- Develop design refinements for selected combined alternative to facilitate resolution of utility conflicts in preparation of future design phases.
- Prepare a technical memorandum documenting the procedures, recommended improvements, and conclusions for all tasks under this project.
The committee members wanted to get an idea of the timeframe on when these things would be completed. Very roughly speaking, Deputy Director Neuberger expected that they would have completed the ongoing tasks and be ready to come back to the committee about that in 3 months. He also thought, very roughly, that the full study would be completed by the end of the year.
Both Deputy Director Neuberger and Director Jungwirth were unwilling to commit to a timeframe because they did not want to prematurely end discussions with Caldwell and Brown on issues. Additionally, there was the possibility of talking with a third party of some sort regarding potential solutions to some of the problems that were highlighted by the study and they did not want to stop that due to a hard deadline. It was stressed, however, the Brown and Caldwell was working diligently and quickly on this and they understood the importance of this study to the City of Appleton.
View full meeting details and video here: https://cityofappleton.legistar.com/MeetingDetail.aspx?ID=1269090&GUID=2C796C17-EE39-4849-9028-E9578D7A57B5
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