Passive Filter – Sustainable BMP for Permanent Stormwater Treatment of Heavy Metals, Nutrients, Hydrocarbons and Sediment

Passive filtration provides a sustainable alternative to classical drainage concepts for source control of hydrocarbons, heavy metals and nutrients that endanger our water bodies. In urban areas with high building density, traditional drainage concepts like wetlands are not available and the concept of decentralized treatment facilities that can be housed in catch basin structures are a viable option for treatment of pollutants. A European and US study is underway to determine the parameters of sustainable on-site retention and infiltration. The European study progressed in three stages. In the first stage the catch basin (hydrodynamic separator and filter housing) was developed and investigated on a laboratory scale, including the hydraulic behavior and the retention of the sediments. Secondly, filters of concrete were assessed in laboratory scale catch basins. The filters were charged with an artificial runoff, which was spiked with pollutants. Concentrations in the influent and the effluent were measured and the design details of the catch basin and its concrete filters were optimized. In the third step field investigations of the catch basin treatment facility were carried out to show the performance of the system while under real conditions