Surplusing works

The contamination of surface water resources by combined water from overflow systems and partly also from stromwater tanks, consists of all the solids which are present in the waste water. This involves a very wide range of dissolved, semi-dissolved, fiber and solid substances with different structures and specific weights (plastic strips, sanitary towels, diapers, condoms, faecal matter, paper etc.).

The increasing restoration of surface water resources to their natural state makes it essential to avoid such discharges of floating material in the future. The construction of immersed walls in overflow structures only enables part of the discharge of floating substances to be avoided, because considerable flow velocities are likely to build up with the generally short spaces which exist between the immersion walls; these velocities tend to increase the discharge of solid material.