First introduced in 2015 for CSO containment, the First Foul Flush Diversion Weir is part of the Radio Data Networks ever expanding Smart Networks portfolio. It is the low-cost way for wastewater utilities to substantially reduce the level of pollution from CSO overflows caused by what is called the “First Flush”, in particular after a long dry spell in summer.
The weir is normally fitted to either the CSO’s discharge pipe or as a modification to its weir structure. In the case of an end of pipe solution is can be bespoke manufactured fit onto the existing pipe or headwall, and can be profiled to fit bot rectangular and circular pipe / culvert overflow pipes / ducts.
In the example above, which is fitted to a 1m diameter outfall pile, the unit works by raising and lowering the spill point of the CSO overflow. Typically raising the spill point at the commencement of the rainfall even and then lowering it after a defined period has elapsed, after which the discharge in the main ought to contain a much-reduced level of pollution. Equally the diversion can be controlled by using the change in suspended solids at the overflow.
The height to which the weir is first raised is normally predetermined by the utilities’ network flow modellers and is set as a compromise between the risk of upstream sewer flooding and pollution reduction.
The whole can be solar operated eliminating the cost and delays of obtaining mains power. Controls can be simple too, with for example a smart level sensor detecting the rate of rise of the sewer due to rainfall that activates the timer. After the time period has elapsed and assuming the level is still raised the weir is then lowered to reduce network pressure.