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London Underground: The Walbrooke Stream/London Bridge Sewer

One of the oldest sewers in London is the London Bridge Sewer. It was built in the 1840s and then integrated into the comprehensive sewerage system that was built under Bazelgette in the 1860s and 1870s. On my final night in London, DS and I went into the sewer via a manhole on a fairly crowded street. It was late at night, but we still had to walk past it the first time because too many cars and people were passing by. Eventually we changed into our waders in a nearby alley, and then opened up the manhole and dove in, praying no cops would happen to be passing at the wrong moment.
As usual, the guys at Sub-Urban had done the original research on this sewer, including researching the chronology of its construction. Reading Nicholas Barton’s The Lost Rivers of London, however, I decided that this sewer was also what remained of London’s Walbrooke (or Walbrook) stream, which was so named because it was the only watercourse that crossed London’s walls at the time when a wall fully encircled the city. (The sewer still passes underneath London Wall Street.) As the only running water to flow under the walls, it must have been important to early London for two reasons: first, as a supply of fresh drinking water, and second, as a sewer which could carry refuse out of the city.
As a freshwater supply, I assumed that there must have been springs that once fed the brook, because how else could enough water be generated to create a consistent stream in the small area of the city? And, in fact, when we got into the sewer, we found that underground springs apparently still flowed in the area, and still fed into the Walbrooke despite the tunnel that now surrounded it. In dozens of places, streams of water came through the brick walls. Some trickled down the sides; others had enough force to spew out between bricks like fountains. All of these streams had apparently forced their way into the tunnel over the century and a half that the sewer had been in use. There was no way to stay dry as we passed through these areas; water dripped from the ceiling, spurted from the walls, and splashed up from the sewage.
As an open sewer for the walled city of London, the Walbrooke must have carried its share of filth even before it was put underground. However, no matter how bad it was back then, we soon found out that today it’s beyond merely disgusting. It was in fact the most noxious, filthy sewer I’ve ever been in. Most of the time sewers don’t actually smell that bad, as flowing water combined with the process of decomposition leaves even human waste smelling more like a barnyard than like a toilet. But the London Bridge Sewer has a very shallow drop compared with more modern combined sewers, and this probably allows a build-up of un-decomposed waste over years. The smell nearly knocked us over when we got into the main channel, where filth and slime came up almost to the crotch of my chest-waders. I was reminded of the name that the explorers from Sub-Urban.com had given it: Stoop’s Limit, so named because even the normally-intrepid explorer nicknamed Stoop, who never balks at anything, finally called a halt in their trip because of the smell.
It was in this sewer, unfortunately, that I found out that my chest-waders had developed a hole near the left knee. When I first felt the wetness along my leg, I though that one of the streams of water from the sides was running down into my waders. When I realized what it actually was, I hit my own limit and called to DS to retreat with me to shallower and drier areas.
In retreating, we found some smaller side-passages. Along the sides of these, a crystalline deposit had built up on some of the old brickwork. I don’t know what mineral it was, but it was gorgeous, especially as it suddenly glittered out of the complete darkness in the light of our headlamps. As I was taking pictures of it, I noticed a tiny, nearly transparent spider that crouched on the crystals.
One other interesting thing about this sewer is that it passes directly underneath the Bank of England. Presumably it is fairly deep where it does so, but it brought to mind the various bank-robbery movies I’ve seen where the thieves manage to find an old sewer tunnel that they use as a base to dig into bank vaults. I’d always thought it was unrealistic, but maybe it’s more of a real possibility than I knew.

London Underground: the River Fleet

Day 1 in London, November 14, ----, 3:30pm local time.
         Ah! London! Sewers!
         I’m sitting right now in a Starbucks in central London, where I popped in to use the bathroom and hang out for a few hours while I wait for my friend to finish work. As I flushed the toilet, it occurred to me that I might see those same turds again in a few hours. Tonight we’re going to visit part of London’s sewer system: the River Fleet, a tributary of the Thames that flowed through central London until it was put underground—and connected to the sewer system— in the 19th century.
         I just arrived in London a few hours ago, flying in from New York. My friend and exploring partner goes by the cryptic name of DS. I met him at his office and dropped off my bags of gear– chest-high rubber waders, gloves, camera, tripod, flashlights, headlamps, spotlights (for light-painting photos), an air meter, even an inflatable inner tube for a possible rafting trip along an underground river in Northern England.
Day 2 in London, November 15, ----, 7am local time.
         Was in the River Fleet last night and into this morning. Just got back to DS’s place. I want to tell the story of our night, but I think I have to start with the river itself:
         THE RIVER FLEET flows from two underground springs in northern London, in Hampstead Heath (a large park on the North-western part of the city) on each side of Parliament hill. The western source starts at the Hampstead Ponds, and the old course of the river just to the south is marked by Fleet Road. The second source is in the northern edge of the park, on the grounds of Kenwood House. A longer series of ponds, the Highgate ponds, show where this spring flows along the eastern side of the park.
         The two springs unite just north of Camden Town. In 1826, it was recorded that the river at this point was 65 feet wide. The Fleet had always one of London’s bigger rivers—the name itself is thought to have been derived from a word meaning, basically, “big enough to float a large boat”—but by the 19th century it was deeply polluted, serving as a drain and sewer for the entire area.
         This was going to be my first time into the London underground. DS and I met with another urban explorer, who goes by the nickname Loops. The manhole that was our goal was a square hatch in the middle of the sidewalk, next to a stoplight on a busy street. It was well after dark on a weeknight, but people walked by constantly. Some were headed toward the hotel just down the street; others were simply walking. At one point when the coast seemed clear, a couple came meandering along the sidewalk. They were obviously and enthusiastically on a date. They held hands and lingered, leaning into each other and stealing a quick kiss. They were moving at a snail’s pace. A dozen feet from the hatch, they stopped completely and admired the ornate stone building next to us. We had already put our rubber waders on, and we sat on a low wall across the street and tried to look inconspicuous in the rubber suits. Finally the sidewalk was empty. We walked over, as quickly as possible in the rubber waders. As DS and I stood casually, Loops knelt down to try to undo the latch that normally prevents anyone from opening these hatches from the top.
         We were here at this relatively early hour because of the tide. The Thames is an estuary in which high tide rises more than twenty feet above low tide. I don’t know how that’s possible; I think it’s because water flowing down the river hits the incoming tide, and the conflux creates tides much higher than I’ve seen on the east coast of the US. But because of this, the final portion of the Fleet is completely flooded from mid-tide onward.
         The hatch was what DS called an “easy-lift.” The hinged square cover was far easier to raise than a heavy manhole—at least, once it was unlatched. Loops was still struggling with it, his headlamp on now. DS bent down to help him. Eventually he threw down the tool he’d been using, and with one finger jammed through the tiny hole he was able to jimmy the latch. We raised the hatch, and then the heavy grill just beneath it.
         I went down the ladder into a small, dry brick tunnel. DS was just behind me. From the bottom of the ladder I looked up: a small square view of the night sky, and then it disappeared as Loops lowered the grate and the hatch cover. In the sudden darkness, the scrape and clang of the metal grating echoed ominously off the Victorian-era brickwork around us. But we were in! I was elated.
         It’s the incredible brickwork that makes the London underground so amazing. The sewer system was constructed under the engineer Bazalgette, who researched and planned in the 1850s and started construction of the hundreds of kilometers of brick tunnels in the 1850s. Thousands of workers dug tunnels and laid brick and stone to make the sewers for the rich and burgeoning metropolis.
         Although few ever saw it, Bazalgett’s sewer system was one of the engineering marvels of its day. Round brick tunnels ranging from six to twelve feet in diameter hold mainline sewers, as well as rivers like the Fleet that had become so polluted that they were best put underground. Round tunnels flow into even vaster tunnels shaped like an upside-down horseshoe, with gently concave floors. Smaller channels were often oval or egg-shaped. (With the smaller end of the egg’s profile pointed downward, this shape keeps sewage flowing faster even when it’s low flow, and that helps reduce silt build-up.)
         These were built not only for sewage and wastewater, but also to drain the city of rain or snowmelt. Because of this, the tunnels often seem needlessly huge. In most of the Fleet, the tunnels range from eight feet up to twenty feet high. The flow of sewage and water we encountered, however, was rarely more than one or two feet high. But in heavy rains these tunnels could fill up almost completely. In manhole shafts, markers ran up the sides with markings every meter, showing that the water could potentially rise much higher even than the top of the tunnel.
         When Bazalgette designed the sewer system, one of the most important things he did was create a system of five “interceptor” sewers, which ran parallel to the Thames at various distances and intercepted the water from the north- and south-flowing sewers to carry the sewage to a treatment plant. Previously, the sewage had flowed directly into the Thames, near where drinking water for the city was withdrawn. Bazalgette’s new system probably saved an incalculable number of lives from disease.
         But when it rains, the flow vastly increases. The rainwater mixes with the human sewage. The treatment plants and interceptor sewers are unable to handle the load. As the flood of water and sewage comes through the tunnel, it rises over the small diversion dams that normally direct it into the interceptors, and a flood of untreated sewage is released directly into the Thames.
         This is a problem common to almost every older city, and is one of the most serious public health issues for urban waterways. Cities try to deal with it in a variety of ways; London is beginning to work on a gigantic deep-underground tunnel which will serve as a reservoir or holding tank for excess sewage when it rains, which can then be slowly released and treated in dryer weather. It should be ready in about 2020. In the meantime, every time it rains, raw sewage is released with the rainwater into the Thames.
         Of course this is an imperfect system, but cities are organic growths that re-use and build on their past. Therefore almost nothing in an older city is going to be perfect, because the systems and infrastructure in use are so often leftover from an earlier period of growth. It’s imperfect, but nonetheless I love seeing the sort of cut-away view of both the history and the physical structure of a city that you get from seeing old underground systems in a modern city.
         Cities that are planned and built in the modern era—like many Australian cities-- always have separate storm drains systems (for rain) and sanitary sewage systems, so they can avoid this problem. But in a large city like London or New York, it’s basically impossible to add in a new separate system for stormwater. The cost is prohibitive and urban populations would never accept the city-wide shutdown that the construction would cause. But this highlights even more what an incredible thing Bazalgette did in constructing the system in the first place—perhaps the largest infrastructure project London has ever undertaken, a masterpiece of Victorian-era brick and stonework that is still fully in use today.
         The bricks inside the Fleet looked as if they had been laid just yesterday. Hard-fired dark bricks formed the floor, sometimes changing to large flagstones. As the tunnel changed shape and size, we could see that the arches were made with four, five, even six layers of bricks. I couldn’t believe the amount of work that had gone into this.
         When we first came in, the water was about two feet deep. Our manhole opened into a small network of access tunnels that led in one direction to the equipment that could raise or lower huge floodgates. Now the gears everything else was almost unrecognizable underneath a swollen, flaking layer of rust and a coating of black, oleaginous mud.
         In the other direction, the tunnel led us into a set of ladders and catwalks that led down into the main tunnel itself. It was incredible: near the outfall here, it was a giant chamber easily twenty feet high and equally wide. The exquisite brickwork vied for my attention with the sheer architectural wonder of it.
         Though most of the standing water near this of the Fleet’s tunnel seemed relatively clean, we quickly encountered sewage when we passed the interceptor tunnel a few hundred feet upstream. A steady stream of obvious sewage flowed into the interceptor, making a waterfall that roared and pounded in the confined space. A four-foot high dam stretched across the main tunnel of the Fleet to prevent it from flowing through the outfall and into the Thames. But it was clear that with even a little bit of rain the water level would rise enough to go over the dam, flowing into the Fleet tunnel and then into the Thames.
         I had on chest-high waders, and was glad of it. Loops and DS both just had hip waders, essentially crotch-high boots. They were easier to move in than my rubber suit, but it occurred to me that if I fell I’d probably be able to stay dry– but if they fell, the high boots would immediately fill with water. The slime that coated everything made it impossible to walk on the sides of the concave floor without slipping, so we trudged along the center. The water would only have been shin-high if it had been standing still, but with the heavy current it splashed past our knees.
         Wading through sewage is a nasty business. In purely sanitary sewers, the water is often a bilious green-brown. (“Sanitary sewers” is the official term for pipes that carry raw sewage, to distinguish them from the cleaner storm drain tunnels designed only to carry rainwater runoff.) In combined sewers, as were built in the Victorian era, street runoff often dilutes the sewage so that the smell is not so bad, and you can sometimes go many steps at a time without being reminded that you’re in a sewer. But the worst part of venturing into sewers is seeing something recognizable: tampons, condoms, maxi-pads, streamers of half-disintegrated toilet paper, or the occasional turd bobbing in the water. We saw all of these as we trudged upstream. The smell was bad, but not awful; only a little worse than I’ve smelled around pigsties or slaughterhouses.        
         But neither the smell nor the sight of floating turds could detract from the excitement I felt. This was the great Fleet River; it had been flowing along into the Thames since before the Romans first established Londinium. The intersection of the Fleet and the Thames was one of the reasons that London had become London, a great city built on a foundation of water-borne trade.
         After the great fire of London, Christopher Wren (the great architect behind St. Paul’s Cathedral) had designed at least one bridge over the Fleet, and I eagerly looked at the walls when the tunnel changed shape or size to see if I could tell where it had been integrated into the tunnel when the Fleet was put underground. I don’t know if I saw it, but what I did see was a palimpsest of London history from Victorian times to the present: old stone arches, Bazalgette’s amazing brickwork, flagstone floors in some tunnels, new sewer line connections of metal pipe, ancient sewer connections of brick tunnel that had been sealed up, because the building or possibly even the entire street that they had served no longer existed. Ancient, rusted ladders led to 19th-century manhole shafts capped by heavy iron covers. Newer ladders, visible in access rooms ten feet to the side of the main tunnel, led to stainless-steel hatches like the one we came in.
         Beyond all this I could see the ancient history of London. With a deepwater port on the estuary of the Thames, all that was needed for the growth of a great city was freshwater rivers. Some would be used for drinking water, others as canals to transport goods. The rivers could also be used for waterwheels to run mills—something the tidal Thames could not do. The Fleet and its companion rivers provided all of these things. And the city grew until it was the center of a world empire, and then it became so large that the small rivers that had fed it were now nothing more than impediments, loose threads in the urban fabric that blocked traffic and occupied valuable real estate. So the rivers were put underground, and as always happens in cities, history and the past were eaten up as the city built for the present and the future. Except that the past is still there– it’s just hidden away, and you have to work a little harder to see it.
         We were done by about 3:30am. We had almost let ourselves get trapped by the rising tide, and in the final section before our exit, the water was so high that it came over the tops of Loops’ waist-high boots. The rising tide made it impossible for us to visit the southernmost section of the river tunnel, even though our exit manhole was so close to it. We would come back the next week at low tide to see the impressive outfall space, a gigantic brick-arched chamber with massive iron doors hanging at one end to serve as one-way valves for the water.
         We stayed in the access tunnels a little longer, wiping down our muddy, sewage-covered gear and packing up for a quick exit out the manhole. Even in that short time, we could see the tide visibly rise in the tunnel near the outfall.
         When we got out DS walked to his office, where he would wash in the bathroom and sleep a few hours on the couch before he had to wake up for his day job. I walked to the nearest Tube station, and had to wait two hours outside the station for the mornings first train. It was absolutely freezing as I waited, especially in my wet clothes, and I sort of wished I was back underground where it’s always warm.

London Underground: the Tyburn River

The Tyburn River
         The Tyburn was one of London’s smaller rivers, nothing like the size of the Fleet or the Westbourne rivers I visited in the city. But I had long looked forward to seeing it, more than any other part of London’s underground. Integrated into this river’s history are two of London’s most important landmarks: Westminster Abbey, which was a nucleus of London a thousand years ago, and Buckingham Palace, a cultural center of London in the modern era.
         Until early in the second millennium A.D., the Tyburn split into two wide, marshy streams just before flowing into the Thames, and the area between them was called Thorney Island. Westminster Abbey was founded in 1065 A.D. on this island. And today, with its course drastically changed and channeled underground by the developing city, the Tyburn River flows deep underneath the grounds Buckingham Palace.
         I was fascinated by the idea of being in a forgotten tunnel underneath such a well-known landmark as Buckingham Palace. I’d be under the noses of the celebrated guards, and they’d never know it. The thousands of tourists that flock every day to see the home of Britain’s royal family would never see what I was going to see, even though it’s only a few dozen meters from the home of the Queen. And this unique experience, shared by so few others, is no small or meager thing. In fact, considered in purely structural and engineering terms, I’m sure that it could rival the Palace itself– the Tyburn’s tunnel stretches for kilometers, with parts as large as ten meters across, and is composed of something like two million hand-laid bricks.[1] But it’s hidden in two ways: physically invisible from the surface, and also unnoticed in the same way that our heartbeats or breathing often go unnoticed. We see the surface layers, whether looking at bodies or at cities, and we often forget the structure behind the surface, just as we often forget the history that underlies the present. But in the Tyburn, as happens with so many historical sites in cities, physically venturing underground and the imaginative process of looking back into history became inextricably linked for me. In both ways, this river would help me in my quest to see new layers of London.
         In London’s early days, the Tyburn River flowed from two small sources in Hampstead (north London). The first was the “Shepherd’s Well” along what is now Fitzjohn’s Avenue, and the second was on the grounds of Belsize Manor. Belsize Manor is gone, but its old location is hinted at by a half-dozen streets in South Hampstead with Belsize in the name (Belsize Road, Belsize Court, etc).
         From these sources, the Tyburn flowed in a generally south-easterly direction; first along the eastern side of Hyde Park, then through the area where Buckingham Palace now stands, and then onward to the site of Westminster Abbey. There it split into two marshy channels, which formed a soggy moat around the slightly higher land of Thorney Island on which the Abbey would grow.
         Because it was so close, the Tyburn was one of the first streams to be diverted to provide drinking water for London. By 1236, the clean water of the upstream Tyburn was already being carried in a conduit to the city. A half-dozen different schemes for bringing its water to the city would be tried in the next few centuries, including one in which three and a half miles of leather pipes were used to transport the water.
         The diversion of the water for other uses, combined with the Tyburn’s small size and the closeness of its sources to the growing city, quickly turned it fetid. With diversions upstream, the flow decreased and the now-small stream became a default sewer for those who lived along it. By 1611 London had made itself independent of local water sources by building an aqueduct to Hertfordshire, but the Tyburn– at least its southern half– had probably ended its usefulness as drinking water centuries before that.

         The river’s course was also drastically changed by the city. Instead of running toward the site of Westminster Abbey, it was channeled further south and ran into the Thames near the site of the Vauxhall Bridge. What’s fascinating to me is that, in fact, it’s impossible to say for sure when the change took place. The amount of London’s growth that predates any complete plan or written record of the city shows clearly how organic a city’s growth is over time. The historian Nicholas Barton places the change in the Tyburn’s course sometime between 951 and 1663. But exactly when, or why, it was changed, or if it was a natural process that happened over the centuries, remains murky.
         Today, the Tyburn is a sewer flowing through a brick tunnel. Officially titled the King’s Scholar’s Pond Sewer, it’s about three meters in diameter when it passes underneath Buckingham Palace. Walking through it we saw many side channels– some go only a short distance to manhole shafts, some connect to side-street sewer lines. There are also consistent tap-ins (individual sewer pipe outlets) from buildings built above the tunnel. Which one of these outlets or side channels ran from Buckingham Palace, I can’t say. But it is likely that at some point we were wading through the Queen’s shit—a more personal side of royalty than most tourists get to see.
         South of Buckingham Palace, we took a look at the surface to orient ourselves. It was now about 3am, and we felt safe in carefully raising a sidewalk manhole to peer out. But a moment after DS stuck his head out, he pulled it back and closed the cover; we were just outside Victoria Station, another of London’s landmarks and probably a bad place to be seen coming out of a manhole.
         In its final section south of Victoria Station, the river follows the winding course of Tachbrook Street. The street is named for a brook that was, essentially, the drastically diverted remnants of the original Tyburn River in the area closest to the Thames; when the tunnel was built it followed this same general path. The original outlet for the tunnel was near Vauxhall Bridge, but a series of floodgates cut off this final connection to the river except in extreme floods. (Wastewater in the tunnel is diverted into a series of interceptor sewers, which carry it east to treatment plants.)

         The many centuries of human involvement in the course of the Tyburn had shrunk it to no more than a small stream long before it was covered, and I expected to see nothing more than the continued small round tunnel. But instead, the passage opened up into a series of much larger galleries. Intricate brickwork curved up into magnificent arches, and lines of heavy stones high in the walls showed where part of it had been originally constructed as an open canal. Ancient, slime-encrusted interceptors carried away the small channel of sewage that ran down the center of these huge spaces. This had clearly not been just a work of pure functionality, as so much urban infrastructure is today; it was in its way a monument to the city and an expression of its glory.
         The floodgates that shut off the southern end of the river—each widely separated from the other– were modern and made of bright steel, incongruous against the dark brick. The first we had passed was mechanized, and we went through it only after Z scouted the tunnel beyond it for the rest of us. (Not knowing if it might close behind us and trap us, I had been too timid to go further until he determined there was a manhole further ahead we could use as an emergency exit.) The second was a closed steel flap weighing tons, and we made it through with brute force and careful squeezing—though crawling through the narrow gap we made brought us face-to-face with the sewage.
         But the third, closest to the river, was firmly and perhaps permanently shut. We couldn’t follow the river to its end. But we had already followed it through a good thousand years of London’s past, and I was quite happy as we made our way back to the silent pre-dawn streets above ground.
Please Note: The Credit for the research and archeological work in uncovering these rivers and their history belongs entirely to others, not me, in particular the extremely dedicated folks at www.sub-urban.com.
The people represented through these websites have my deepest thanks for exploring these rivers and their history and for guiding me around: www.sleepycity.netwww.sub-urban.comwww.silentuk.com; and Loops.
For further reading: The Lost Rivers of London, by Nicholas Barton.

[1] This is a very, very rough guess, based on the size of the tunnel and the number of layers of brick. I didn’t actually count them all.