Balancing flow levels to maximise available catchment storage capabilities

Much has been said recently about balancing Sewer effluent flow levels through the extent of a Combined Sewer or Surface Water catchment or Flood Relief system.

Traditionally designed flow control systems are extremely difficult and costly to retrofit, so with the significant exception of SUDs solutions which are incorporated at either the head or at the periphery of a catchment, where new developments seek to discharge to an otherwise underperforming catchment with inadequate capacity, this has very much been the extent of any improvement made to date.

For a sustainable solution to be successfully achieved and deliver a meaningful and timely solution that will also achieve the stated aims and objectives of our UK Water Utilities, then it must be clear that a retrofit solution is essential. Whilst attempts must be made to enhance the design and improvement of existing drainage design wherever the opportunity is afforded, the recognition must be that time is very much our enemy. For this reason, TOTEX budget need to be carefully reassessed, and more funding made urgently available for significant investment in this vital area.

By storing increasing quantities of effluent within the upper extents of any catchment, and effectively slowing the passage of increased effluent resulting from storm surcharge or long duration rainfall events, we have the potential to achieve so much. Primarily the aim would be to reduce or eliminate localised property or urban surface flooding where this impacts adversely on everyday life. By reducing CSO discharges to our Rivers and Watercourses, helping Water Utilities meet the stated commitment to the Environment Agency and the UK government by progressively cleaning our Rivers and Watercourse. But perversely, by achieving their Carbon Neutral goals using the very same alternate solutions, a factor that has not even been considered as a benefit when using traditional flow control solutions.

Over recent decades, certainly since the privatisation of the UK Water Industry, Water and Sewerage Utilities have moved away from Preventative Maintenance towards methods which now are almost exclusively reactive isolated problem-solving measures. This affects so many aspects of their day-to-day operations, but none more than methods used to clean sewers and resolve the thousands of blockages that occur annually for all water companies throughout the country. This reactive maintenance machine has grown in both size and influence and despite being proven to be both inefficient and detrimental to our environment, still dictates every attempt made to change it. The concern in this instance is that this resistance to change has the potential to delay the consideration of technology that balances flow throughout the catchment whilst providing a preventative maintenance alternative.

So just what can be done to help our Water Utilities move away from inefficient, harmful, and clearly outdated technology. How can we improve the efficiency of our drains and sewers to allow more effectively the transfer of effluent through the catchment from the user to the receiving Sewage Treatment Works?

The answer is there and it is easy one to answer. But it will clearly be a bitter pill for a lucrative and powerful framework sector to swallow.

Simple retrofit attenuation devices such as Flusher and Flusher2 technologies. These solutions can be readily inserted inside existing Manhole structure, in many cases in just a few minutes. By strategically positioning these throughout the required areas of the catchment the requirements for balancing flow levels can be achieved, and the automated release of the effluent which is triggered at a predetermined storage level, subsequently cleans and keeps the catchment free from both sediment and the risk of subsequent blockages.

These techniques have been developed to increase hydraulic efficiency within virtually any pipeline, or larger sewer culvert, including those which result from a lack of efficiency caused by them suffering from sedimentation or the recurrent formation of blockages.

It is acknowledged sediment in quantities as small as 2% of the cross-sectional area of any pipe can result in a 10-20% reduction of the full pipe discharge capacity. Robert Banasiak – Instytut Meteorologii i Gospodarki Wodnej IMGW · Centre for Flood and Drought Modelling

Inefficient hydraulic performance has severe implications on the efforts required by Water Utilities to reduce CSO discharges, or to limit the high number of properties continuously at risk of flooding. Jetting would not be deployed to clean such minute quantities of sedimentation, nor could High Pressure Jetting be cost effectively considered to maintain catchments in a constantly clean and free flowing state. On the other hand, automated sewer cleansing systems such as Flusher2 provide 24 hour, 365 day per year protection and offer precisely this solution. A repeating Flusher cycle releases a significant volume of low-pressure water, at an increased hydraulic velocity, turning virtually any underperforming section of sewer into an over performing one. Within a typical combined drainage catchment, Flusher2 will send between 40 -100 flushing pulses through the catchment, cleansing and mobilising all sedimentation both upstream and downstream for significant distances, (up to several kilometres). This staged attenuate and intermittent release process effectively slows the movement of effluent through the catchment, providing a multitude of benefits.

FOG and Fatbergs can also become a thing of the past with Flusher2 used to both prevent and eradicate these sewer monsters and avoid the unnecessary risks taken by the personnel currently employed to remove these problems by hand. It can be used in conjunction with all current dosing solutions increasing its effectiveness by continuously exposing the active product to the entire surface area of the Fat as part of each attenuation and flushing cycle. Each flush removes softening fat progressively until the problem has been resolved. Flusher2 then eradicates the conditions that would allow this problem to return, without the need for further regular dosing.

The problems referred to previously for Sewer Jetting would be gone immediately, with no opportunity for damage to above or below ground infrastructure, or to our environment or the public health. This solution is Carbon Neutral using only the power generated by the effluent that already passes through our pipes and sewers. CAPEX and OPEX costs will be reduced hugely, leaving more money to be spent on other aspects such as the expansion and reinforcement of our sewerage catchments to accommodate plans for new and increased housing developments and first-time sewerage schemes.

Flusher and Flusher2 technology is every bit as important as systems such as SUDS or traditional attenuation systems including Hydrobrakes etc. The increase in use of low use water, or water miser systems, which are now championed by Water Utilities are laudable, but these and the previously mentioned flow control solutions create their own problems by allowing even lower volumes of flow to pass through the upper extents of a catchment reducing further self-cleansing hydraulic conditions. Flusher2 can provide an invaluable tool to combat these problems. Previously mentioned flow control systems are already widely used and cost many thousands of pounds for each individual installation. Flusher2 on the other hand is a low cost retrofit solution that requires no engineering design or enabling costs. It can be installed in minutes and is operational immediately and costs just hundreds for each installation. Larger bespoke design Flusher systems are available for use in trunk sewers or larger diameter or irregular shaped sewer structures and whilst these are much more costly they are significantly cheaper than the alternatives.

There are so many other opportunities where Flusher2 and similar automated techniques can benefit us now and, in the future, and this includes Highways and Rail Track Drainage. Land drainage or maintenance of watercourses etc. Our Water Utilities and others must be encouraged to embrace change and develop a new and cleaner future.

A more sustainable future that is based upon Prevention not Cure!

Caen Locks showing demonstrating above ground the way that Flusher attenuates flow below ground.






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