Touby Run Watershed - Flood Hazard
To mitigate decades of widespread flooding in downtown Mansfield, Ohio, EMH&T is working with the City to develop a flood hazard mitigation plan. We are performing a watershed-scale analysis of Touby Run to quantify flood hazard potential under existing conditions and with proposed flood hazard mitigation alternatives. This engineering effort includes a detailed rainfall-runoff model for the Touby Run watershed and a HEC-RAS hydraulic backwater model to establish existing flood hazard conditions and evaluate potential solutions to reduce the frequency and extent of flooding. The analysis of regional stormwater detention basins has considered various locations where significant storage volume could be achieved though implementation of dam impoundments. The flood hazard mitigation plan is targeting the 100-year flood event as well as simulating a recent severe flood event which occured in August 2007 to demonstrate the preferred flood hazard mitigation solution is capable of providing the level of flood protection desired by the community. The engineering efforts associated with this project include consideration of the State of Ohio’s dam saftey regulations in completing the preliminary engineering design and associated construction cost estimates. To complement the engineering analysis, EMH&T has completed an environmental investigation of the dam impoundment locations to understand potential impacts to jurisdicational waters and a Phase I and II Environmental Site Assessment (ESA) of land which was formerly occupied by an industrical land use. Those results have been factored into the preliminary design of the flood protection infrastructure. Additionally we have prepared an Open Space Framework Plan to allow the City to envision opportunities for enhancing public park spaces in the areas which will be dedicated to this infrastructure.