Heavy Metal Pollution of Roof Runoff and Potentials for Decentralized Treatment

Abstract

For uncoated copper and zinc roofing systems, annual average runoff rates are estimated to be 1.3 g Cu/(m² ∙ a) and 3.0 g Zn/(m² ∙ a), respectively. Thus, the resulting roof runoff waters are frequently subject to treatment prior to discharge and infiltration into groundwater. However, currently there are neither federal requirements nor national standards for decentralized stormwater treatment systems receiving metal roof runoff, which cannot be approved by the German Centre of Competence for Construction (Deutsches Institut für Bautechnik). Therefore, this study investigated preliminary test criteria proposed by the Bavarian Environment Agency (Bayerisches Landesamt für Umwelt) of five infiltration systems from three manufacturers for which approval has been granted in Bavaria. Nevertheless, additional research is needed addressing service and maintenance requirements of decentralized treatment systems and compliance issues regarding implementing the proposed federal contaminated soil ordinance (Mantelverordnung).