Stormwater Runoff Research – ms consultants / Ohio Department of Transportation, Office of Research
Ohio Statewide Project
ODOT’s Office of Hydraulic Engineering Research, in collaboration with ms consultants, the United States Geological Survey (USGS), and STONE is undergoing a research project to evaluate alternatives for post construction best management practices (BMP) to address the difficulty of designing such BMPs for transportation projects due to their linear nature, restrictive construction limits and limited rights-of-way. The research project aims to take advantage of the features common to roadway projects (e.g., grassed shoulders and medians) to evaluate soil amendments that may increase infiltration capacity, promote evapotranspiration, and serve as a water quantity BMP.
Twelve sites were chosen across the state of Ohio, geographically distributed to allow for varying weather conditions throughout the state. At each site, within the grassed medians of ODOT-maintained rights-of way, the team developed site-specific flow monitoring and installed equipment to capture and record the rate, volume, and frequency of stormwater runoff generated by the roadway.
The soil amendment process consisted of incorporating high-infiltrating soil materials into the top layer of existing soil along the sloped grass shoulder of the roadway. As the stormwater runoff sheet flows off the roadway, the amended soil is intended to decrease stormwater runoff volume by increasing infiltration, evapotranspiration, and initial abstraction of the grassed shoulder. Several soil amendment materials and amendment depths were installed and analyzed to evaluate their performance. Post-amendment flow monitoring will be conducted to evaluate the effectiveness of soil amendment as a stormwater volume reducing BMP by comparing the pre-amendment runoff volumes with post-amendment volumes.
STONE’s role has included:
- Meetings with ODOT and Ohio EPA
- Development of Conceptual Amendment Plans
- Assistance with the identification of Research Sites
- Amendment system Installation Observation
- Research Evaluation and Input
As part of the first phase of the project, STONE prepared the “Soil Amendment Design Alternatives Summary and Final Recommendations” report. This report provided design for the soil amendment plans to be used in vegetated filter strips (VFS). VFS are generally located along roadways, in areas with gradual vegetated slopes, between the roadway shoulder and edge of the water conveyance (e.g. ditch). VFS generally reduce runoff through infiltration, storage, and evapotranspiration. Amended VFS (AVFS) have the ability to increase the amount of stormwater infiltration within the same area. Amendment materials researched included natural and manufactured materials. To manage costs and constructability, materials identified were readily-available in Ohio, materials that Ohio highway contractors typically deal with, and materials that were not cost prohibitive. Based on the goals of the project, the materials researched, discussions with the research team, and the desire for usable data to be analyzed following post construction monitoring, initially three amendment designs and two depths were reviewed. Following further research in input from ODOT and the team, final recommendations were made along with recommendations for construction installation practices.