Out of sight, out of mind. What to do with the wastewater?
In the second half of the 19th century, conditions in Germany still stank to high heaven. Wastewater, and in some cases even faeces, was routinely disposed of in the gutters. The bodies of surface water received this unpleasant cargo – out of sight, out of mind.
Naturally, some of this wastewater infiltrated into the soil and contaminated the groundwater. In the Emscher-Lippe region, widespread mining subsidence furthermore frequently caused water drainage to fail completely. The results were devastating epidemics. Only an overall plan for the region, which would control wastewater disposal and purification, drainage and flood protection, could sustainably improve the situation for the population along the rivers. In 1899, the EMSCHERGENOSSENSCHAFT took on these Tasks for the Emscher region. The LIPPEVERBAND followed in 1926.
In the course of the mining era, the waterways were expanded into drawn-out, open wastewater collectors, which safely transported away stormwater and wastewater. The risk of epidemic disease was banished. Today, it is possible to keep the wastewater out of the waterways. It is routed to the wastewater Treatment plants through underground sewers. The wastewater-free waterways now have the opportunity for near-natural restructuring. They thus become available again to the population as living elements of a river landscape.
What to do with the rainwater?
When it rains, the mixed water sewers of the Emscher and Lippe are filled with rushing water – and the wastewater treatment plants eventually reach the limits of their capacity. Then stormwater overflow basins and sewer overflows prevent the system from collapsing. Equipped with significantly larger diameters than normal sewers, these act as underground buffers for the volumes of mixed water than cannot immediately be processed by the wastewater treatment plants. After the rain stops, the stored water is gradually routed to the wastewater treatment plants.
In the stormwater overflow basins and sewer overflows, the pollutants already begin to settle to the ground. In the event of sustained rain, the heavily diluted and mechanically pre-clarified wastewater can thus be discharged directly into the waterways without excessive contamination.