Approval of technical SUDS in Germany

Carsten Dierkes, Antje Welker, Martina Dierschke

Friday 3 july 2015

14:30 - 14:45h at Europe 2 (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Flood resilient cities and infrastructures

Parallel session: 16I. Extreme events - Resilient

Water laws and regulations in Germany stipulate the use of stormwater infiltration systems. Decentralized SUDS (sustainable drainage systems) offer a good alternative to traditional end of pipe treatment systems for stormwater runoff from urban areas. Besides “green” SUDS like grassed swales or rain gardens technical infiltration systems like plastic boxes or arches in the underground get more and more important in the dense urban environments. Choosing decentralized systems leads to several advantages like higher flood resilience, lengths of sewers can be reduced and no additional space in the urban environment is required. But stormwater is very often highly polluted and must be treated before infiltration. Proprietary stormwater treatment systems therefore can get an official general technical approval in Germany to secure a proper function. The laboratory test procedures of the Deutsches Institut für Bautechnik (DIBt) take into account hydraulic behavior, removal of pollutants (total suspended solids (TSS), copper, zinc and petroleum type hydrocarbons (TPH)) and maintenance. The tests are carried out using four different rain intensities that represent the German rainfall bandwidth. Pollutants are added to a synthetical stormwater runoff and the tests represent specific loads that are taken from a literature study. Some tests are carried out at filter columns or segments if the facilities exceed a certain size. At this time 17 general technical approvals are issued. These are permeable pavements, linear filter channels and filter shafts in front of underground infiltration facilities. In this paper the general requirements and the basics for the tests are summarized. Maintenance and operation of those facilities must be regulated and taken into account. Some technical approvals of the DIBt require the completion of maintenance contracts. In compliance with the above-mentioned requirements for hydraulics and pollutant removal a long-lasting operation can possibly be guaranteed.