Mark Hendriksen

150 years later the population is now closer to 10 million. This is what’s happening…

Forward Thinking BC. To get a handle on how advanced the thinking was on ‘waste management’ thousands of years ago, the Mesopotamians had already figured clay sewer pipes around c.4000 BC. Utilised to remove wastewater, and capture rainwater in wells. But, let’s fast forward through history… The world continued to progress their early sewer/sanitation systems as other ‘influencer countries’ went on to build their own versions in places such as; Egypt, Greece, Rome, China (first toilet paper), Pakistan, India [Indus Valley & Harappan civilisations] and so on. All of which points to the fact that over the 1000s of years since then, until the mid-1800s, not much progress (in terms of 6000 years of sewage management) had been made. The investment in Tideway is the biggest single sewer investment in Europe since Sir Joseph Bazalgette’s day.

Heading Downstream. Since the dawn of civilisation, human settlements had grown and evolved best around rivers where, within close proximity, fresh water could be sourced – and wastewater crudely diverted downstream to be diluted and supposedly ‘vanish.’ Importantly for this brief article, by comparison to today, the world’s population was smaller, people used less water, planet earth was greener, it was way ahead of any industrial revolution, and there weren’t factors like ‘travel and tourism’ nor other modern-day developments to take into account.

A Changing World. In this regard, the world was relatively well looked after for many millennia i.e. none of the ‘nasties’ pollution, chemicals, plastics, and certain industries destroying our environment and ecology, about who we so often hear about in the news. Wars and weaponry were also far less sophisticated and caused less damage to ‘less’ infrastructure. Back then the earth’s surface had less ‘ground’ taken up by houses and other buildings as well. This led onto natural drainage being a whole lot better and, on which note, brings us onto rainwater, the importance and unpredictability of which we’ll explain about in a short while. What hasn’t changed is that ‘Everybody Poops.’

Better Sanitation for All. Before we move on to Sir Joseph Bazalgette and what he did for London, something that’s worth flagging for the sake of perspective and comparison is global sanitation. Even now in the 21st century 25% of the world still doesn’t have access to basic sanitation and/or water. The impact for all of us, as major contributors to what goes down the loo [toilet] and regarding what needs to be done with our waste, is a priority in keeping all of us healthy. It is an ongoing challenge for us and a far greater one for the less fortunate 25%. Sanitation needs to be on everyone’s radar and in our conversations, ‘Out of Sight should not mean Out of Mind.’ Diseases spread, and diseases travels – as the current pandemic has clearly shown. Let’s look back at London 1858, and then we’ll return to 2020.

Sir Joseph Bazalgette. The name Bazalgette (pronounced Bazal’jet) is synonymous with Sir Joseph Bazalgette. His proposal was an ambitious solution to what the press at the time in 1858 called, ‘The Great Stink.’ His colossal project was accepted and it became a turning point for an ageing and inadequate sewer system that emptied directly into the Thames. This wasn’t ‘just a bad stench’ it was also related to a substantial number of deaths from the water-borne transmission of diseases [typhoid and specifically a cholera epidemic.] A toxic cocktail of human excreta, slaughterhouse waste, and industrial chemicals poured freely into the River Thames, turning it into an open sewer. Between 1831 and 1866, approximately 40,000 people died from cholera in London alone (2% of the population) an equivalent of 200,000 people today.

We should bear in mind that the population of London at the time was c. 2m. Bazalgette had the foresight to construct for a population of 4m, double that number. The cost in today’s terms would be roughly £1bn. Currently, London is heading towards a population of 10m, add to that ‘transient’ tourists/visitors to London, estimated to have been around 20m+ in 2019, and that’s a lot of waste to move out of town (or any majorly populated area in the world for that matter.)

In brief, here’s what happened back then. Bazalgette’s scheme was an extraordinary feat of engineering involving the construction of major new ‘intercepting sewers’ that would gather sewage from the existing collection of sewers at the time, and move it further down the river. On the north bank of The Thames, sewage would be carried eastwards as far as Beckton, eight miles east of St Paul’s Cathedral, to be stored and then discharged on the outgoing tide. On the south bank, the sewage would flow as far out as Crossness, two miles further downstream of Beckton, and discharged there. The project was completed by 1875. However, at the time, although it moved out of the more populated areas of London it ended up ‘downstream’ but still back in The Thames. In other words, the problem hadn’t gone away, it had gone elsewhere.

Sewage Treatment Works. What was missing from the original big idea was that no ‘sewage treatment works‘ were part of the plan at the time, i.e. no separation of effluent and water before to sending it back into the river. It wasn’t until a disastrous accident in 1878 caused the underworld and earth to collide, when a passenger steamboat sank after crashing into a coal-carrying ship downstream from the two pumping stations… just after they’d pumped 75m gallons of raw sewage into the river. The resultant pressure from MPs in the 1880s forced the first ‘treatment works’ for raw sewage, where the solid waste was ‘settled’ and subsequently only the liquid waste was discharged into the Thames at Beckton, and also 2 miles farther along at Crossness. The Bazalgette drainage system was passed to the London County Council and they appointed a Chief Engineer, Sir Alexander Binnie, to be responsible for all of their infrastructure. He designed the first sewage treatment works (originally just lime settlement) at the ends of the sewer outfalls created by Sir Jospeh Bazalgette.

However, that wasn’t quite the end of the problems. By the time Bazalgette died in 1891, 5.5m people were living and defecating in inner London. 1.5m more than anticipated just 30 years earlier. The other key part to operating and improving London’s sewers were called ‘combined sewer overflows.’ In the USA a more descriptive term is used, ‘storm-water regulators.’ All of which brings us back to a typically British subject, ‘the weather.’

What’s Caused the Latest Stink for the UK? Today, we have the benefit of Sir Joseph’s incredible construction and the ever-improving ‘sewer treatment works,’ but new challenges like ‘wet wipes’ and all sorts of other things that shouldn’t get put down the toilet (except the 3Ps.) Apart from the dangers of bacteria to ourselves, bacteria in sewage can also absorb the dissolved oxygen from the water, killing off fish and water-dwelling plants as well. All of which brings us onto one other equally significant call of nature apart from our own, and that’s rainwater. Rain needs to drain for which reason even now, 150 years after the original ‘Bazalgette’ sewers were completed, around 40 million tonnes of raw sewage still spills, untreated, into the River Thames every year. The present-day population, (as mentioned previously) has now more than doubled. Fortunately, a few years ago, the European Commission [EC] and European Court of Justice made a new ‘stink’ about the latest problems, which subsequently resulted in the new £4bn construction project known as ‘Thames Tideway,’ owned by a consortium of investors, and it’s respectfully called ‘Bazalgette Tunnel Limited.’

Professor Chris Binnie (great grandson of Sir Alexander Binnie), chaired the Thames Tideway steering group for 5 years and we got in touch to ask, in relatively simple terms, what’s going on with London’s sewers – now due for completion by 2024 and referred to as the ‘Super-Sewer.’ However, ahead of his reply, let’s try and make all the pieces finally fit neatly together. We’ll begin, as we did, by figuring what ‘combined sewer overflows’ means and why, as the old saying goes, ‘when it rains it pours.’ If the storm is too great for the sewers/drainage pipes to cope with there’s what’s called a, ‘combined sewer overflow‘ [CSOs.] These are a collection/system of pipes and tunnels designed to simultaneously collect surface runoff (the flow of water occurring on the ground surface from excess rainwater) and sewage water – in a shared system. When this relief structure is overloaded valves are opened that still release the combined wastewater, untreated sewage and runoff into the Thames.

From Bazalgette to Bazalgette + ‘Combined Sewer Flows.’ If the CSOs are only used occasionally, that’s considered an acceptable amount of ‘nearly just stormwater.’ But if the frequency increases greatly, so does the, ‘not so pleasant addition to the stormwater’ that ends up back in the river. As Chris Binnie explained, “The European Commission had given guidance that 20 ‘spills’ per year might be the limit. Without doubt, there were about a dozen CSOs that exceed such a frequency. So, the ECJ found the UK in breach.” To help do the math, there are about 50 combined sewer overflows happening in London each year. Chris added that, “Over the last 10 years all the sewage treatment works have been upgraded and now meet the required standards including spill frequency, so the only issue was with the central London combined sewerage system.” In 2016 Thames Tideway began constructing a giant tunnel, seven metres wide and it will run for 25 kilometres to intercept sewage that would otherwise pollute the river, click the link to Thames Tideway to dig deeper (excuse the pun;)) The aim is to capture, store and move the vast quantities of raw sewage and rainwater across London connecting to 34 of the most polluting CSOs via transfer tunnels, and taking sewage (that would normally be pumped into the Thames) to a treatment facility at Abbey Mills in east London – designed many years ago by a certain Joseph Balzagette.

A Breath of Fresh Air. Work on the ‘super-sewer’ started 4 years ago, we’re halfway there. It’s backed by investors but, in case you weren’t aware, at some point it will appear as a cost on your water bill too. This isn’t only a matter for London and a future post will look at other world cities facing similar challenges. Ultimately, this won’t be the last time London’s sewers need to be better figured out for the future. Global sanitation is probably the world’s biggest and most important issue if humanity is to survive. Ask the WHO, UN, WTO, UNICEF and, and, and – it’s not a sexy subject but unless we overcome this Taboo, we are burying our heads in the sewers – that, as it was back in 1858, will be extremely dangerous. A few subsequent articles on the project, and their links, can be accessed below. Meanwhile do contact us with any comments or questions. We look forward to returning next week with another post on ‘loos and no. 2s.’ Until then have a good week…

1. The Museum of London, ‘How Bazalgette Built London’s First Super Sewer.‘
2. BBC 2017 ‘Work begins on London’s super sewer to stop Thames becoming a toilet.’
3. The TV 3 part Series from 2018 [now available via Daily Motion] The Five Billion Pound Super Sewer.
4. Wired, ‘London’s Super Sewer Won’t Solve The City’s Epic Poo Problem.‘ Dec 2018
5. An update from the BBC in Feb 2020 ‘Inside London’s Super Sewer.’
6. ‘Tunnelling Work Restarts on Super Sewer‘ from PBCToday May 13 2020.