WASTE SYSTEMS


A potential killer beneath our feet


Brian Back, HND, BEng (Hons), CEng, FIET, founder of the Zero Pollution Network – a ‘network of solution providers that aim both to tackle aquatic pollution, climate change, and sustainability issues, and to improve Corporate Social Responsibility and Environmental Sustainable Governance’, who is also CEO and CTO of radio telemetry specialist, Radio Data Networks, discusses the significant health risks to patients, staff, and visitors, from blocked sewers and drains in hospitals and other healthcare facilities. He highlights some of the key technologies for detecting such issues before they become a major problem.


With published papers uncovered dating back to 20031


citing the persistence of


SARS and coronavirus in urine and sewage being as long as four days, the current coronavirus (COVID-19) outbreak should make hospital managers in a variety of clinical settings acutely aware that their staff run an increased risk when dealing with blockages, and that a consequential spill of sewage into any public spaces could have fatal consequences.


Oblivious to the many that work in, visit, or become patients within, the healthcare sector, there are drains and sewers threading their way through the fabric of every building, under pavements and car parks, all carrying the waste stream produced by our healthcare sector – which emanates from toilets, kitchens, drains, and waste macerators. Out of sight and out of mind the vast majority of the time, people are oblivious to the existence of this intricate network of pipes and stacks until disaster strikes and a blockage occurs. As a minimum, a blockage can lead to a toilet not flushing, a sink failing to empty, or urinals backing up. Irrespective of the cause, the failure to address a majority of blockage quickly can lead to a spill that has the potential to spread infection and disease like a tsunami across a hospital.


Radiological risk factor


The problem, however, doesn’t stop with infection, as there is also a radiological hazard in many sectors of healthcare. This relates to ‘hot stacks’ and ‘hot drains’, i.e. those that carry radioactive isotopes that are a by-product excreted by patients undergoing cancer treatment. It is absolutely true that there is no single ‘magic bullet solution’ to preventing blockages. Even if you have draconian policies against flushing ‘un-flushables’, such as wet wipes and nappies, stop kitchens from using cooking fats, oils, and grease, and outlaw the use of clinical


blockages induced by mechanical failure, if a blockage occurs once, then it is likely to happen again and again, making certain locations become regular ‘hot spots’.


Static head pressure is best measured, Brian Back says, using an atmospherically compensated pressure transducer attached to the stack or a lateral via a sealed air nipple.


waste macerators, there is still the issue of sedimentation/scaling that can lead to stacks and pipes closing up and blocking. In any drainage network there will be certain locations more prone to blocking than others. Generally, setting aside


Monitoring for blockages If anywhere requires an omni-present X-ray or ultrasound machine, then I would argue that it is our sewers, stacks, and drains. Unfortunately, there is no simple or single solution for detecting blockages, and the task is made more challenging through our use of steel/iron stacks and/or stacks hidden in ducts and risers with fire check breaks.


Having been a pioneer in the art of blockage detection, I have to admit that there is no single technique, and indeed the solution required will vary from location to location. Furthermore, one of the largest issues with any monitoring system/solution is verification – simply how can you demonstrate that a system is working, and will trigger when you need it, without blocking the sewer on a regular basis to test its operation.


A BDT-based blockage detection system.


Reporting blockages from underground chambers I would be most surprised if you could find a more inhospitable location for any electronics to survive in than our sewer and drainage systems. Moisture, corrosive gases, detergents, bleaches, rags, tissues, steam, hot and cold water, rodents, and a whole cocktail of chemicals, await the sewage blockage detection system. There is also the chance that a potentially explosive atmosphere could exist, necessitating any electronic devices used complying with the ATEX Directive. Were all this not enough, there is then also the issue of how to get the alarm message out of the chamber back to the hospital’s BMS system, without chopping up floors to run cables, changing manhole covers, or compromising cyber security. Finally, whatever is installed needs not


April 2020 Health Estate Journal 41


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