Biofiltration (aka bioretention with underdrains) has emerged as a preferred stormwater treatment option in California and has been demonstrated to meet many stormwater management goals.
However, substantial questions remain about biofiltration media specifications for specific pollutants and site conditions. Additionally, field scale monitoring studies have indicated the potential for export of pollutants from biofiltration. Finally, the cost and quality of materials can vary regionally, which is of specific importance in updates of standard biofiltration specifications that will go into widespread use.
Recent efforts to improve biofiltration soil specifications in California have included material surveys from regional suppliers, testing of media components, column studies of individual components and combinations, and full-scale design and monitoring projects. Information from these studies, as well as review of past studies in the International Stormwater BMP Database, has provided the basis for updated specifications and/or alternative specifications to achieve higher and more consistent performance for specific pollutants while reducing risks of pollutant export. Through regional supplier surveys, the ability for contractors to supply materials meeting enhanced specifications is inherently vetted.
This presentation will provide a summary of recent and ongoing efforts, including the practical findings that can be transferred to municipalities and project proponents in California. Project examples that will be presented include: 1. Recent media supplier availability and cost surveys and media component testing conducted in the San Diego and Los Angeles Region for municipal and private clients 2. Updates to standard biofiltration media specifications developed as part of three Southern California BMP Design Manuals 3. A column study for a land development project to develop and support an alternative biofiltration media specification
This presentation will summarize recent research findings and lessons learned about putting these findings into practice. The intended audience includes municipal stormwater managers and specifying engineers.