The Michigan Department of Transportation (MDOT) is at a deficit for wetland mitigation credit in the Maple River Watershed due to construction of the St. Johns Bypass on US 127. MDOT requested design plans for the creation of a forested wetland that are cost effective, innovative, and fit within the landscape.
Through ArcGIS mapping and field surveys, the construction site was characterized to determine hydrology, topography, and soil classification. In order to determine the hydrologic regime of the system a water balance excel model was developed to predict inundation period and daily water height. Site design was optimized to minimize excavation, maintain wildlife usage, and ensure vegetative establishment.
Lab scale soil percolation rate testing by constant head method
Results of the water balance indicate sufficient water for a forested wetland ecosystem. Stop-log control structures and an earthen berm constructed from on-site soil are utilized to facilitate the necessity for precise water depths. The design includes small areas of emergent and scrub-shrub wetland to promote ecological diversity.