In Dakota County, the Vermillion River frequently overtopped CSAH 50 during 10-year storm events, far below acceptable flood protection level of service. Adding complexity, the river is a designated trout stream, with sensitive trout habitat located directly within the project corridor, requiring careful environmental consideration throughout the design process.
Hydraulic Analysis and Resilient Roadway Design
SRF provided final design services for the reconstruction of a four-mile segment of CSAH 50, enhancing connectivity between Lakeville and Farmington. Using the HEC-2 model and available data, SRF conducted a detailed hydraulic analysis to balance the proposed bridge opening with controlled weir flow over the roadway. A variance from the Minnesota Department of Transportation (MnDOT) allowed the redesigned roadway to overtop at a frequency greater than the 25-year event, an innovative solution that balanced performance and environmental impact.
In addition to waterway and bridge design, SRF’s water resources consulting team addressed key stormwater and flood management challenges by:
- Designing storm sewer systems for urban segments, integrating water quality treatment before discharge to the trout stream
- Sizing cross culverts in rural areas to handle future growth
- Designing a box culvert in Lakeville to manage flood protection via controlled overtopping while maintaining hydraulic capacity
- Creating a wetland mitigation site to receive treated water from a detention basin near the Vermillion River
Preserving Habitat and Planning for Growth
Throughout the project, SRF coordinated closely with the Cities of Lakeville and Farmington to support their long-term growth plans. The design approach emphasized sustainability by preserving trout habitat and enhancing flood resilience while minimizing disruption to surrounding communities.
Resource Links:
Minnesota Department of Transportation
City of Lakeville
City of Farmington
Internal Category:
Water & Environment
Resilience & Sustainability
More from:
Minneapolis, MN
Saint Paul, MN
