Laboratory Media Test Comparisons to Long-Term Performance of Biofilter and Media Filter Treatment-Train Stormwater Controls

Abstract

Stormwater biofilters and bioretention controls have been extensively studied and are commonly encouraged as effective stormwater controls. Most of these controls incorporate media to enhance pollutant removal. There is much published research describing laboratory tests on the performance and selection of different media, and many field tests on media treatment of stormwater, but complementary long-term, full-scale field tests compared to prior laboratory tests are not as common. The purpose of this paper is to compare the laboratory evaluations of treatment media targeting a broad range of constituents of concern, to the results of long-term monitoring of full-scale stormwater controls using the selected media. The laboratory evaluations identified which media blend would reduce concentrations of constituents of concern to help meet National Pollutant Discharge Elimination System (NPDES) permit discharge limits and benchmarks, given site specific influent concentrations, when deployed in the field. Besides pollutant reductions, treatment flow rates and maintenance requirements were also of a consideration when selecting the media blend, especially determining the useful life of the media before clogging and/or pollutant breakthrough. Statistical comparison tests of the laboratory results with the full-scale field results resulted in similar effluent quality for most measured constituents (especially for lead and the critical form of dioxin), at all field treatment locations. Therefore, the laboratory observations were confirmed by the long-term, full-scale, stormwater control monitoring activities. The selected media has resulted in reductions in concentrations of the constituents of concern, over long periods of use.