The answer found in nature
U.S. Air Force Airman 1st Class Anthony Rouleau, 633rd Civil Engineer Squadron readiness and emergency flight member, removes rocks from the curb inlet during a Filterra Stormwater Bioretention maintenance at Joint Base Langley-Eustis, Va., April 5, 2018. Stormwater runoff flows into the system through a curb inlet on the street making its way through specialized media, mulch and natural vegetation that capture pollutants and naturally clean the water. (U.S. Air Force photo by Airman 1st Class Anthony Nin Leclerec )

Photo by: Airman 1st Class Anthony Nin Leclerec |  VIRIN: 180405-F-ML658-1136.JPG