As the City of Kenosha embarked on a comprehensive analysis of their storm water infrastructure from both flood control and water quality perspectives, the City was hit with back-to-back intense rainfall events in July of 2017 that resulted in significant local and regional flooding. The greater City of Kenosha area received approximately 4.5 inches of rain in a 5-hour period on July 10th, 2017 and another 3.2 inches in a 14-hour period on July 12th, 2017. Taken together, this 48-hour event was classified as an approximate 200-year event (0.5% chance of occurring in any given year).
The immediate public health and safety concerns tied to this flooding event doubled down the City’s efforts to simultaneously develop a long-term plan for the future, while also quickly addressing some of the most pressing concerns. To accomplish this, the R/M-led design team worked hand-in-hand with City staff to develop a comprehensive 3D flood model using XP-SWMM software along with a City-wide water quality model. Along the way, City staff were diligent in updating their storm water GIS database via historic records research and field survey. This updated digital database not only assured the City of having accurate GIS data, it also became the basis for the flood control and water quality models.
The use of GIS data provided the City with two distinct advantages:
The presence of robust digital data quickened the model development process, saving time and money.
The ability to integrate multi-dimensional flood limits and water quality “hot spots” into a graphic setting simplified the public’s understanding of the results.
Previous modeling methodologies required an immense amount of both engineering knowledge and time to digest the results. Conversely, the ability to overlay flooding results within the City’s current mobile GIS or directly into Google Maps meant that City staff, elected officials and residents could graphically see how their system was functioning and what was needed to fix it in a straight-forward manner. This technology can also be utilized to produce flooding “movies” that show how a given area floods over time throughout a simulated storm. Taken together, these are invaluable public/elected official education tools.
The City of Kenosha also had a strong desire for the recommendations to mesh with other City initiatives, helping to tackle MS4 permit compliance and flood abatement in a creative manner. As an example, the City is currently planning ahead to incorporate recommended storm water components into their 2019 street projects to realize cost benefits from combining multiple types of improvements into a single project. The prioritized roadmap of recommended improvements has also allowed the City to plan ahead from a funding perspective, opening up potential grant funding opportunities that would not exist without a completed plan.
The City of Kenosha is a 24-square mile community in southeast Wisconsin. The City’s watersheds are separated by the subcontinental divide, consisting of both beachfront on Lake Michigan and storm water discharge to the Mississippi River.
Detailed flooding maps using a multi-dimensional SWMM-based H/H model and GIS were prepared for each drainage basin within the City limits.
Integration of model results into a GIS mobile viewer has allowed the City to determine the footprint of street flooding based on specific storm events.
Project recommendations maximized the City’s limited storm water funding by developing a 5-year CIP that works in conjunction with other City planning documents.
Developed a road map for the compliance with future Wisconsin Pollutant Discharge Elimination System MS4 regulations and future TMDLs at the lowest possible cost.
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Photo credit: TMJ4
About the Author
Steven C. Wurster, P.E., CFM, CPSWQ
Senior Vice President and COO, Client Team Leader
Steve thrives in the area of storm water management. His experience as a project manager and project engineer includes municipal water resources master planning, storm water management facilities design and review, NR216 permitting and compliance, storm water utility implementation, environmental permitting and hydrologic, hydraulic, and flood plain modeling. He is also experienced in site grading and erosion control design, utility design, transportation facilities design, development review, construction management and general municipal consulting. Steve has been employed by Ruekert & Mielke, Inc. since 1999.