The Seseke Programme
The restructuring of an entire river, together with its subsidiary waterways, is a complex and time-consuming project. The work began in 1986 with the planning for the conversion of the Braunebach stream in Kamen. The Heidegraben in Bergkamen and the Massener Bach in Unna followed. The restructuring of the Dorfbach and Süggelbach, Kuhbach and Körne was completed step by step in 2006. The planning framework for the restructuring work is provided by the Seseke Programme, which coordinates the following tasks:
- Elimination of open wastewater drainage
- Construction of four decentralised wastewater treatment plants, instead of the central river wastewater treatment plant in Lünen
- Ecological redesign of the waterways
- Restoration of the waterways as recreation and adventure areas
- Integration of the waterways into the cities
- Ensuring flood protection
Alongside the construction of the wastewater treatment plant, the work for the restructuring project was divided into three fields of activity:
Before the waterways could be restructured, the wastewater had to be removed from the wastewater channels and drained separately, so that the waterways would only contain clean water and purified wastewater. In order to implement this separation from a practical perspective, underground sewers needed to be built, in order to collect and drain the wastewater. The complicated soil and gradient conditions made the planning of these sewers a very complex task. Due to the many years of industrial history in the Seseke region, the issue of contaminated sites and the research for potential obstructions to building work also played an important role. The separation task was completed in 2004.
Due to the high degree of soil sealing in the catchment area, the sewer system in the Seseke area must collect large volumes of stormwater. In order to avoid oversized sewer systems and optimise the retention facility requirements, decentralised stormwater management is required. The aim is to allow the rainwater to infiltrate locally, or to drain it into bodies of water at a restricted rate, wherever this is possible at reasonable cost. As numerous projects show, this often has a positive effect on the residential environment.
Stormwater that nevertheless gets drained into the mixed water sewer cannot be routed to the wastewater treatment plant at an unrestricted rate. Stormwater treatment plants and stormwater overflow basins ensure that highly polluted mixed water never gets into the bodies of water, even during heavy rainfall events.
After the sewers and stormwater treatment plants had been built, the former wastewater channel could be restructured to become a near-natural waterway. Important individual measures included the removal of the concrete base plates, the widening and restructuring of the technical profiles, and the removal or restructuring of transverse structures that impaired the continuity of the waterway. Images typical of this type of waterway were used for orientation.