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.