INFLUENCE OF FLOW RATE AND MEDIA GRADATION ON THE COST-EFFECTIVE DESIGN OF STORMWATER FILTRATION BEST MANAGEMENT PRACTICES FOR THE REMOVAL OF TOTAL SUSPENDED SOLIDS

Filtration-based stormwater treatment relies upon a physical medium for the removal of solids from stormwater runoff. This physical medium can be composed of any number of materials, which in turn can exist in many different gradations and be operated at many different filtration rates, not all of which are optimal with respect to short and long-term performance needs. Three perlite media configurations were subject to identical filtration tests to assess their performance under high and low filtration rate conditions. Evaluations were conducted using a radial flow filter cartridge and performance was compared on a side-by-side basis for the removal of a silt-textured material. The results indicate that media gradation and filtration rate appear to be related in that the correct combination of these two variables must be married in order for performance to be significantly different than that which would be observed based upon manipulation of one of these variables alone. The conclusions of this study enhance the foundational understanding of stormwater filtration BMP design.