Media Filter Drain: Modified Design Evaluation

Abstract

The media filter drain (MFD), a stormwater water quality treatment best management practice, consists of media made up of aggregate, perlite, gypsum and dolomite in a trench located along roadway shoulders with gravel and vegetative pre-filtering facilities and optional underdrains. One of the many benefits of MFDs is the effective removal of dissolved zinc and copper from roadway runoff. However, the existing design includes use of an aggregate gradation that is no longer readily available (old design). A more readily available and economical aggregate gradation has a slightly lower percent of finer material (new design). This project evaluates if the new design is as effective as the old design at enhanced dissolved zinc and copper treatment. Findings from laboratory research performed on columns filled with new media versus columns filled with old media indicate that the new media initially has similar removal efficiencies as the old media for large storm events. Accelerated aging of the new media indicates that removal efficiency for dissolved zinc and copper of the new media has not decreased after 15 years of simulated use.