Biofiltration has become common in Minnesota’s urban landscape because it is one of the most robust stormwater treatment practices available to designers. Stormwater professionals and practitioners, however, still face challenging decisions while designing these practices and often feel as if they are guessing when selecting media components and designing these practices. In particular, the most commonly used and recommended biofiltration media mixes have been shown to export phosphate, potentially contributing to water quality impairments. This increases environmental risk and uncertainty when attempting to implement TMDL recommendations. Thus, the objectives of this research are to:
- Identify which local and sustainable biofiltration media are effective for filtration rate, supporting plant growth and microbial function, and that do not release phosphate
- Document local sources, simple tests or metrics, and/or design specifications that can be used by practitioners to reliably and repeatably obtain a biofiltration practice that functions as expected.
The communication, outreach, and technology transfer plan includes updates to the Minnesota Stormwater Manual and the Minimal Impact Design Standards (MIDS) calculator, webinars, videos, and articles in widely distributed newsletters. Results will also be incorporated into existing or new professional training, continuing education, and certification for stormwater professionals and practitioners.
This study will fill the knowledge gap of the best available biofiltration media components that can be locally sourced in Minnesota and accurately specified. This will empower practitioners with the confidence to design biofiltration practices with the best available knowledge and understanding of media components in Minnesota.