Reducing Stormwater Runoff and Pollutant Loading with Biochar Addition to Highway Greenways

TRB's National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) Final Report 182: Reducing Stormwater Runoff and Pollutant Loading with Biochar Addition to Highway Greenways documents a new approach that has the potential to dramatically increase nutrient removal efficiency and simultaneously reduce stormwater volume while avoiding new infrastructure. Stormwater discharge from roadways is a source of pollution for waterways that must be treated and controlled. Increasing stormwater regulations on nutrient loads are compelling state transportation agencies to undertake stormwater restoration to reduce nutrient loads and where possible stormwater volume. While existing stormwater technologies such as detention ponds and new Low Impact Development features can remove nutrients, the required increase in load removal and runoff volume reduction will be costly on a watershed-scale since more real estate is required for increased treatment using current technologies. This report explores the addition of engineered biochar to highway greenways. This stormwater treatment is achieved using a waste material, as biochars are often created from waste organic matter, e.g., sawdust.