Bioretention Soil Media Specification for Stormwater Treatment: Research Progress, Challenges, and Opportunities
Bioretention systems utilize engineered soil media, i.e., bioretention soil media (BSM) for stormwater capture and treatment. Conventional BSM specifications, generally included in local or state bioretention design guidelines, recommend using compost/mulch as an amendment for sand, sandy loam, loamy sand or topsoil. However, bioretention systems installed using conventional BSM often become sources of contaminants, including nutrients, metals, and pathogens. Alternative amendments to replace or supplement compost-based BSM have been tested, mostly in laboratory setting with few field trials. However, municipalities or regulatory agencies have been conservative or slow to adopting the novel BSM amendments into their BSM specifications. Consequently, newer BSM amendments are infrequently applied at field-scale, thereby missing the opportunity of implementing the technology innovations.
In this talk, we will discuss advantages and limitations of various BSM amendments, present a framework for their implementation based on performance need and site conditions, and recommend improved BSM specifications for regulators and design engineers. The conversation intends to inform the research community the practical needs and challenges faced by stormwater managers to implement newer BSM amendments and provide a guideline to the stormwater managers on how to adopt the innovation in BSM amendments to meet the regulatory and design needs—a two-ways feedback process that could catalyze further innovation in the development of sustainable stormwater treatment technologies.