The CTH M corridor passes through one of the most environmentally sensitive areas in Dane County, bordered by wetlands, wildlife areas, and protected parklands where numerous protected and endangered species live. Delivering a major infrastructure project in this setting required a design approach grounded in avoidance, minimization, and respect for the natural landscape.
Instead of relying on conventional stormwater systems, the project incorporated natural, passive solutions such as depressed grass medians, flat-bottom ditches, flood storage areas, and dry detention basins. These features improve water quality, reduce long-term maintenance needs, and maintain the corridor’s rural character while providing resilience to changing weather patterns.
Additional measures included over 700 feet of boardwalk to span wetlands without disturbing hydrology, fish habitat enhancements coordinated with regulatory agencies, and species-specific protections for endangered wildlife. To further minimize construction impacts, the design team implemented two unique approaches: a subgrade stabilization strategy using geotextile fabric and specialized backfill to reduce marsh excavation depth from roughly 35 feet to about 20 feet, and specially designed steel sheet piling near Six Mile Creek that remained in place after construction. These solutions protected adjacent wetlands while maintaining the integrity of the existing bike path during and after excavation, reinforcing a commitment to environmental stewardship from design through construction.
The CTH M Reconstruction project was honored with a 2026 APWA WI Project of the Year Award in the Transportation category for projects between $5M–$25M.
#Sustainability #EnvironmentalStewardship #GreenInfrastructure #Engineering
