Photo Gallery From Open Sewer to Nature Oasis
The Emscher River flows over 80 kilometers (50 miles) through the old coalfields of the Ruhr Valley, the industrial rust belt in western Germany. It's a gigantic open sewer -- the largest in Europe. Slaughterhouses and steel mills discharge their offal and refuse here, and the river is a depository for heavy metals and feces.
The reason behind this unfortunate and somewhat pre-modern situation is that the ground is sinking in many parts of the Ruhr Valley. Mine shafts honeycomb the substrata, making it impossible to build conventional underground sewers. Clay pipes would burst, and masonry ducts would crack. Given the circumstances, the region long ago opted for an open system in which the steel and mining industries have been dumping a growing torrent of toxins and filth since the 19th century.
Shortly after German reunification, in 1990, 19 municipalities and numerous companies joined forces to create the Emschergenossenschaft, or "Emscher Cooperative," and draft an ambitious plan. The goal is to use a high-tech sewage system to relieve the burden on the river and its tributaries and transform them back into babbling brooks flowing past blossoming meadows.
While the river's concrete banks are replaced with greenery, plans call for a huge sewage pipe, nearly 3 meters (10 feet) in diameter, to run underground over a distance of 50 kilometers to Dinslaken on the Rhine River. It will also gather all the muck from the tributaries. During this journey, the water will be processed at three sewage treatment plants, including this one in Bottrop.
This sewage drain made up of 20,000 concrete pipe segments will be off-limits for human maintenance and cleaning crews, as it's simply too dangerous. Instead, specially designed service robots will maintain and clean the pipes, as well as locate cracks. The camp of a Roman legion and a mammoth tusk have been found during the digging process.
In order to keep the sewage flowing, the main pipe has to have a downward slope of 1.5 per mill, meaning it drops 1.5 meters for every kilometer in length. In order to make this possible, the slurry stream needs pumping stations. Plans call for building three of these colossal water elevators.
