Practical experience in handling decentralized stormwater quality treatment devices for traffic area runoff

In the course of a sustainable groundwater management, traffic area runoff is more often percolated on-site. Due to traffic-related emissions, atmospheric pollutions and temporary punctual emissions (accident/construction site/event) the traffic area runoff can be polluted heavily to some extent with heavy metals or organic substances. Because of the natural retention by vegetated topsoil a contamination of the soil-/groundwater-system is effectively prevented. In urban regions, this protective effect often must be provided on the smallest possible area by technical drainage solutions like filter substratum channels or shaft systems. The challenge is to provide enough permeability by the devices to prevent backwater and thereby following limitations for the traffic. Coincidental a contamination of the soil and groundwater must be prevented sufficiently, even at high flow rates.

Besides numerous laboratory studies only a few scientifically documented experiences in the field exist, especially concerning the service life and the risk of clogging as well as maintenance and operation of the devices.

The objective of the research project, funded by the Bayerisches Landesamt für Umwelt (LfU), is performing independent application-oriented research on decentralized stormwater quality treatment devices, which are approved by the Deutsches Institut für Bautechnik (DIBt). For this three treatment plants (two shaft systems and one filter substratum channel) with different functionalities will be constructed in Munich at a heavily trafficked street under equal conditions. To capture seasonal influences (e.g. pollen in spring, heavy rainfall and dry periods in summer, fall of leaves in autumn and the influence of deicing salts in winter) the study will be executed for a period of one and a half years. The emergence of (hazardous) substances, their detention and remobilization under the influence of deicing salts and long-lasting impounding will be studied. Besides operational aspects will be recorded and analyzed. Additionally insufficiently investigated substances like antiknock agents (MTBE/ETBE), cyanides contained in deicing salts and fine particles will be monitored. By the research project a well-founded background will be provided for the Bavarian water management offices (Wasserwirtschaftsämter) to assess different treatment systems and consult operators. The results will also be used for the work and regulation of diverse national acting technical committees like the DWA and DIBt.

The research project runs from February 2017 to March 2020.