SPONSORED FEATURE
Flusher2 can be installed as a retro fit solution within
virtually any manhole chambe.
the Charring Cross area of London, was sufficient to allow the head of water to force the remaining plug of FOG down the sewer at force. Fortunately, all personnel were able to speedily evacuate before a serious incident occurred. The resulting Fatberg blocked the sewer at its point of connection with a downstream sewer and emergency cleansing works were conducted to prevent flooding. This was a classified as a Health and Safety “near miss” which should at the very least make the consideration of all possible non- invasive alternatives an important and necessary consideration. However, clearly this message has been disregarded.
If others don’t, then do it yourself?
In the absence therefore of our Water Utilities proactively considering feasible Sewer Flushing techniques, I personally decided to investigate and develop an option that would deliver an effective repeatable automated high volume release solution. I looked again at all existing solutions, past and present starting with Roman Tipping Buckets, Victorian River Flushing inlets which were used to trigger the release of stored river. I travelled around the world to consider other concepts, including those that had been considered but had potentially been mothballed due to a lack of commercial interest or engagement.
Eventually I designed a simple counterbalanced tipping gate which unsurprisingly I called “Flusher”. The design required nothing more than effluent passing through the sewer to accumulate behind the gate which was purposes built within a manhole chamber. At a predetermined height of surcharge where the weight/pressure of effluent exceeded the counterbalance weight the release was triggered. The tipping gate resulted in an immediate and forceful flush with more flow volume passing than would ever have been achieved by a bucket or storage chamber. Once the effective flush had passed and water levels had dropped, the weighted gate snapped closed recommencing the repeatable flushing cycle. The concept worked perfectly, and numerous trials and installations were conducted, with considerable success. Sewers which had previously been affected by recurrent sedimentation or the formation of blockages were restored to an effective operational performance. Surprisingly at the time, but clearly understood now, sewers previously affected by FOG build up, were instead unaffected by the problems that had once required frequent emergency attendance or periodic cleansing as part of a regular maintenance schedule.
If at first, you don’t succeed! The benefits of the original Flusher technique were considerable.
40 | February 2022 |
www.draintraderltd.com
However, the limitation of the initial concept for all but the most significant problems were high installation costs. Non-standard manhole chambers had to be accurately surveyed with bespoke fabrication of the gate and the associated baffles and supports. This concept was clearly difficult to promote, despite the long-term benefits, and would be disregarded by many due to high initial costs. Some authorities did however continue to invest and achieved significant benefits, some of which are still very much in use today, virtually a decade after their original installation. This goes a long way to demonstrate the value and resilience of the Flusher solution.
Try, try, then try again…...!
Once again, the thinking cap was needed, because if the solution had any chance of competing with reactive sewer jetting which incorrectly considered to be a cheaper option, then something else was clearly needed.
So once again the focus shifted and instead of looking at the largest blockages, Fatbergs within man-entry sewers, instead we looked at where most of the problems exist. Within pipe sewers. Pipes represent 95% or more of the total Foul and Combined sewer network.
A push fit design was developed and launched as Flusher2. This could still be installed as a retro fit solution, but within virtually any manhole chamber. Instead of being fabricated to suit the individual chamber, it was designed as a simple push-fit device that would slide into any standard pipe size and be immediately operational thereafter. The first models were once again trialled and demonstrated revealing the same cleansing capabilities as the larger original Flusher versions. Modifications were made based upon in the field experiences and additional safety factors were incorporated to deflect wet wipes, sanitary products, nappies, and other fibrous materials, forcing them under the opened gate by accelerating the flow beneath the open gate during the release phase. I also designed an overflow or bypass tube. This was provided to address the concerns of other drainage engineers and to provide time for any required maintenance to be conducted in the unlikely event of the Flusher2 gate failing in a closed position.
The performance and capabilities were proven!
The cleansing effects of these Flusher2 systems had been expected to be good, however in practice the benefits were seen to be far better than ever anticipated. Subsequent hydraulic modelling performed by Atkins Global clearly demonstrated Flusher2s capability to generate hydraulic enhancements both upstream and
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