In the 1990s, many improved separated systems were implemented to prevent water quality issues caused by, among other things, illicit connections. Due to their design (a stormwater system with 4 mm storage and a pump overcapacity of 0.3 mm/h), these systems often discharge a large amount of "thin" water towards wastewater treatment plants (WWTP) —about 70% of the net rainfall annually. For this reason, many improved separated systems are shut off or adjusted upon request by WWTP managers. However, this can sometimes lead to water quality problems in the receiving surface water.

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On behalf of STOWA, we developed the VGS 2.0 concept: an "optimized" improved separate system that can direct "dirty" water from misconnections to the WWTP while discharging "clean" (storm)water locally. This significantly reduces the flow of "thin" water to the WWTP. An existing improved system can be converted to VGS 2.0, for example, by installing an additional pump. A control system determines when water should flow to the WWTP and when it can be discharged directly into the surface water.

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We have extensive experience with VGS 2.0 and are happy to help assess whether it could be a suitable solution for your system. If so, we can support the implementation by creating a functional design and developing the pump control system.