DEFINING RAIN GARDEN FILTER BED SUBSTRATES BASED ON SATURATED HYDRAULIC CONDUCTIVITY
Water is one of the planets most precious non-renewable resources, yet it has become one of the most polluted and neglected. The number one cause of water pollution in many watersheds originates from non-point sources, such as storm water runoff. Rain gardens trap storm water runoff and remove pollutants. To effectively remove pollutants, storm water runoff must be held in the rain garden substrate as long as possible. Since a substrates water retention characteristics are defined by it particle size distribution, rain garden filter bed substrates are best classified as horticultural substrates. Filter bed substrates sand and slate were tested with composts (biosolids, food, and yard wastes) added. All composts increased course and decreased fine particles when added to sand. Sixty percent amendments of all composts gave the greatest increase in medium particles in sand. For slate, food and yard composts decreased fines, biosolids increased fines, and enzyme had no impact on fines. All composts had no or little impact on medium and coarse particles when added to slate. A 20% addition of all composts resulted in optimal saturated hydraulic flow and greater retention of simulated stormwater runoff in both the sand and slate based substrates. Sand with an initial particle size distribution of 83% fine, 17% medium and 0.25% coarse particles should be amended to achieve a final particle size distribution of 67% fine, 30% medium, and 2% coarse. The coarser textured slate (31% fine, 44% medium, and 24% coarse) should have a final particle size distribu-tion of 30% fine, 48% medium, and 22% coarse particles.
Kraus, H., Pledger, R., Riley, E., Fonteno, W.C., Jackson, B.E. and Bilderback, T. (2014). DEFINING RAIN GARDEN FILTER BED SUBSTRATES BASED ON SATURATED HYDRAULIC CONDUCTIVITY. Acta Hortic. 1034, 57-64
urban stormwater, biofiltration, stormwater BMP