FLOW AND SURGE
Flood management system enters UK market
A system that has been designed to maximise sewerage capacity in flood events is being launched in the UK. On behalf of Uhrig, Ian Clarke reports on this significant development
I
nvestigations of many of flash flood events have shown that poorly maintained and/or under-capacity sewer systems form part of the rainfall management problem, with pipes blocked by silt or other detritus preventing full capacity usage. However, sometimes there was simply too much water passing through a given section of the pipeline for it to handle at the time of the event.
A closer look at this shows that often the lack of capacity in the sewer became apparent only when too much water arrived at a single point in the sewer at one time. The discharge from this point was then insufficient to prevent the flood emerging through surface access points and manholes.
Flood storage
In conventional flow control systems, flows are allowed to build to a point where they automatically discharge into overflow pipes as flow rates increase. This can lead to major unwanted and potentially contaminated discharges into surface waters. This type of situation would therefore be better management of flows prior to overcharging of these pipelines at any critical points where the flooding might occur. The German company Uhrig has developed an in-sewer flow management system specifically designed to address this requirement. The system utilises the full capacity of the sewer over its whole length to manage and control high potential flood water flows during major rainfall events. It does this by utilising specially designed and installed computer monitored flow measurement systems, remote- controlled sluice gates and moving weirs positioned at strategic points along the pipeline length, prior to the point where flows enter the sewage treatment plant.
The system uses modern flow monitoring techniques and automated control systems triggered by the flow monitoring systems to open and close the sluice gates as flow volumes in the pipeline change.
This allows the pipe upstream of the sluice gate to be used as an immediate ‘short-term’ flow storage facility, with flows being held
34 Water & Wastewater Treatment April 2011
Schematic of the Uhrig system when installed
Schematic elevation of the flood control provided by the Uhrig
A computer monitored and operated flow control sluice gate as used within the Uhrig system
above the sluice gate and released by the automatic sluice control only when the pipeline below the sluice has the capacity available to
An Uhrig discharge weir
handle the flow. This not only manages the flow rate of water, but also minimises any need for discharge through overflows. It does
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