There are few things in life that age well; cheese and wine show great balance, structure and complexity as they age, and more so when paired together. Without having to sacrifice overall performance, it would be great to expect similar traits from our stormwater best management practices (BMPS), particularly green infrastructure practices like bioretention and biofiltration. Biofiltration treatment mechanisms rely on a synergistic community of living organisms such as plants, microorganisms and organic media, and when paired with proper maintenance, can ensure long-term sustainable quality and hydraulic performance. Evaluating the long-term effectiveness of stormwater BMPs should be a critical component for determining appropriateness in meeting water quality objectives.

Since 2007, Contech Engineered Solutions LLC has continuously evaluated a range of pollutants via third-party field sampling and laboratory analysis at three (3) different sites in Maryland and Virginia utilizing Filterra® Bioretention Systems, a proprietary biofilter that shares primary pollutant removal processes with traditional bioretention. The study sites contained differently sized and aged systems treating various land uses and received regular maintenance, which contributed to the systems overall health and performance. Monitoring duration varied by study site, ranging upwards of 13 years.

Filterra systems utilize a high-flow rate bioretention media enabling the treatment surface area to be sized more optimally, i.e. smaller, than traditional bioretention systems. In a recent field evaluation to correlate flow and quality performance, monitoring was completed to verify that the treatment flow rate of the system has not been compromised over time. Additionally, media profile samples and plant growth progression were evaluated to understand changes in system dynamics. Based on all available data, Filterra continues to meet or exceed performance claims, including that of traditional bioretention systems. This presentation will focus on the Filterra’s decade-long monitoring effort and discuss consequences of not considering longevity when selecting BMPs for water quality compliance.