Prepared by Craig Fairbaugh, A.M.ASCE and submitted to the Summer 2024 Currents
Billions of dollars are spent annually to install and maintain stormwater filtration media systems in the United States that protect our streams, rivers, lakes, and oceans from pollution. Systems that utilize filtration media include green infrastructure practices such as bioretention and high rate biofiltration, and also non-vegetated practices such as sand filters and high rate media filters. Even though there are volumes of research from journals, conference papers, and industry white papers on some of these systems, there is no cohesive guidance document which advises on the applied effectiveness of different stormwater filtration medias. Thus, the purpose of the EWRI Stormwater Media Filtration committee is to investigate the physical, chemical, and biological factors which influence media filtration of stormwater for performance, reliability, and longevity.
Currently, the committee is working on a Technical Report for publication by ASCE with the purpose of informing regulators, academia, researchers, industry, engineers, and designers on the latest technology and best practices of stormwater filtration media. For the past two decades, there have been a wide variety of filtration medias used throughout the country to meet Clean Water Act and NPDES permitting requirements; however, there is no existing guidance which synthesizes the research, performance, longevity, and procurement best practices we have learned. This is the goal of the Technical Report with a draft completion date of December 1st, 2024.
The Technical Report includes three main tools that are intended to be used in sequence:
- an infiltration feasibility and level of treatment/pretreatment flow chart,
- a summary of media performance in the field, and
- a summary table of current standards and analytical methods to ensure media quality assurance and quality control (QA/QC)testing.
The infiltration feasibility flow chart helps the user understand if and when a filtration media system shall be used. Next, the summary of the media performance document will direct the user to the appropriate filter media(s) and resulting performance that supports water quality goals. Lastly, the QA/QC table will ensure that the selected media is tested, procured, and transported adequately to achieve the expected water quality results. Taken together, the goal of these tools is to improve the selection, performance, and procurement of filtration media.
To aid in the media performance matrix, the committee is currently focusing on collecting field monitoring data. There is a specific need for bioretention field monitoring data where the system has an underdrain only and infiltration is restricted. There is an additional need for field monitoring data of bioretention medias which use amendments to improve effluent water quality. Common bioretention media amendments include biochar, iron, aluminum, and water treatment residuals. Please reach out to the committee if your organization has access to bioretention field monitoring data that can be used to support the development of the Technical Report. The data will be anonymized and reported in a similar format as the International BMP Database summary statistics report.
For more information and to participate, please contact the committee Chair, Craig Fairbaugh, or Vice-Chair, Curtis Hinman. This is a fantastic opportunity for both young professionals and experienced practitioners to be a part of an important report to protect receiving waters of the United States from pollution. We welcome and look forward to your participation!