At the federal level, the Water Resources Act requires that precipitation water be handled as locally as possible. This can be promoted through the use of decentralised rainwater treatment plants. At the national level, a distinction must be made between the discharge of precipitation water into surface waters and the discharge into the soil or groundwater system. There are no federal legal requirements for discharge into surface waters, but country-specific requirements must be met. Requirements for discharge into soil or groundwater are regulated on the part of the Federal Government by the approval principles of the Deutsches Institut für Bautechnik (DIBt). Since 2005, DIBt has been developing approval principles at federal level for the discharge of traffic area runoff into soil and groundwater. In the approval process, a distinction is made between surface pavements and decentralised systems for connecting larger areas. New approval principles were formulated in 2011 for decentralised plants for the treatment of traffic area runoff with subsequent discharge into soil and groundwater. The specified test procedure is based on the guideline values of the Federal Soil Protection Ordinance (BBodSchV) and provides limit values for the parameters filterable substances, copper, zinc and mineral oil hydrocarbons.
The effectiveness of the treatment plants is tested under laboratory conditions. The tests of the AFS and MKW retention capacity are carried out on the original plant, the tests of the heavy metal retention on a reduced filter segment or a filter column. The aim of the approval principles is to create a framework for the granting of approvals by the building authorities. In North Rhine-Westphalia, the separation decree also allows the operation of decentralised precipitation water treatment plants with subsequent discharge into a surface water body. By proving the comparability of decentralised plants with at least one central rainwater clarification tank with regard to material retention and continuous operation, approval can be granted at state level.
Tests under laboratory conditions are performed at PIA GmbH. In addition, as shown in the photos, we offer charging solutions individually adapted to the test piece or manufacturer's requirements.