As stormwater quality regulations become increasingly stringent, civil engineers are turning to stormwater filtration Best Management Practices (BMPs) to meet the demand for higher pollutant removal efficiency. In this blog post, we will explore the fundamentals of stormwater filtration, focusing on pollutant removal mechanisms, sizing methods, filtration mediums, and the advantages of proprietary systems.

Stormwater runoff is a significant source of water pollution, carrying various pollutants from urban areas into natural water bodies. Most stormwater treatment efforts have focused on the capture of total suspended solids. Still, significant pollutant loads can be attributed to dissolved pollutants, such as heavy metals, nutrients, and organic compounds, which can have detrimental effects on aquatic ecosystems and public health.

At first glance, singing the praises of one’s own employer might seem a bit self-serving, but as a dedicated environmental professional, I do feel the story is worth telling.  I don’t have to work here after all, but Contech’s sustained commitment to developing effective stormwater control measures (SCMs), advancing stormwater science, and advocating for robust stormwater policy has kept me motivated to keep at it for 22 years and counting. 

Eliminating illicit discharges within our storm sewers through an illicit discharge detection and elimination (IDDE) program is critical to improving the overall health of local waterways. Illicit discharges, like stormwater runoff generated within the municipal separate storm sewer system (MS4), flow directly into a receiving waterbody. Whereas post-construction stormwater control measures (SCMs) are designed to reduce typical pollutants (e.g. sediment, trash, and nutrients) in stormwater runoff prior to it entering receiving waters, illicit discharges pose a unique challenge because they contain atypical pollutants that can go untreated and may also increase the maintenance frequency of post-construction SCMs.

Stormwater quality regulations continue to expand to include treatment criteria for total phosphorus. Phosphorus is now the second-most-regulated pollutant in stormwater runoff after total suspended solids. While much has been written about BMPs used to remove total phosphorus, we shouldn’t underestimate the role BMP maintenance has on reducing phosphorus levels. More specifically, we should take into account the timing of maintenance events and the type of maintenance being performed.