A charcoal-like material made from leaves and branches that collect on forest floors could be a cheap, sustainable way to keep pollution from washing off roadways and into Georgia’s lakes and rivers.

Engineers at Georgia Tech and Georgia Southern University have found that this biological charcoal, or biochar, can be mixed with soil and used along roadways to catch grimy rainwater and filter it naturally before it pollutes surface water.

Their tests found the biochar effectively cleans contaminants from the rainwater and works just as well in the sandy soils of the coastal plain as in the clays of north Georgia. Their biochar-soil mixture can be easily substituted for expensive material mined from the earth that’s typically used on roads. 

Though they focused on Georgia, the researchers said the findings could easily apply across the U.S., providing a simple, natural way to keep road pollutants out of water sources. They published their approach in the Journal of Environmental Management.

Learn about their system on the College of Engineering website.