"The gas is mainly hydrogen sulphide and it gives that rotten eggs smell, " said Gary Paley, of Darlington, who has been a sewerage engineer for 18 years in Yorkshire. "It usually occurs when sewage is being pumped long distances. It can become septic as it does not travel from A to B quick enough. It can also occur in flat areas where the speed of flow is slower.
"The gas will eat concrete if not dealt with. I remember that the sewer near the racecourse in Thirsk had been almost totally eaten by the gas and just the reinforcing bars from inside the concrete pipes were left. "
Monday, 21 December 2009
Carshalton And The Mother of All Drain Pressure Relase Pipes
I was taking a short walk between the two 'villages' of Sutton and Carshalton the other week (and in the process coming across enough bits and pieces to make a future decent posting) and was just going over the railway bridge on Carshalton Road when I caught sight of a most intriguing Drain Pressure Release Pipe in the far distance.
View Larger Map
These pressure release pipes are often referred to as 'Stink Pipes', which seems quite an inappropriate name for something as elegant. They serve a couple of purposes - firstly as a way of preventing any build up of pressure in underground sewers in the event of a blockage or any other build up of gas, and secondly to make sure that any corrosive hydrogen sulphide gas was vented off. There's a very interesting article on the subject in the Northern Echo with the following explanation from a sewer engineer
Useful utilitarian things then stink pipes, but not an obvious candidate for decorative trappings. I'd seen the same design when a passenger in a car near the Purley Way in Croydon, but this was the first opportunity I'd had of taking a few pictures and having a closer look and it was well worth the effort - even if it was a bit tricky to capture all the details.
There are a couple of things about this pipe that really stand out. The first is the height . Most of the pipes I've documented before have been considerably shorter but this one rises above the street like a needle, possibly up to twice the height of some others. The second eye-catcher is the extraordinarily ornate top fixture comprising a large arrow, a globe with four 'trumpet' funnels and a spiked spire piercing what looks like a crown.
Of course having had the opportunity to have a look at this one and marvel at its complexities, I then spotted another one down a side road on the journey back to Sutton! As it was a only a few streets away it's tempting to assume it's part of the same pipe run but as it's on the other side of the railway line that would suggest that either the drain is very deep or it's on a parallel, but separate, spur. The second pipe on Weihurst Gardens is, however, also close to the railway line which might suggest the drain and the railway followed the same course.
Then yesterday I was going through Carshalton - on Park Hill Road this time - and spotted a couple more of these pipes along the roadside, One yet again by a (different) railway line with a second pipe (lacking both spike and crown) just down Park Hill.
View Larger Map
There is very little distance between all four of them which again suggests they were bought and erected at about the same time on the same main drain (or two). If they are venting off of a main drain it might also be the case that it is fairly deep and potentially 'lively', possibly releasing considerable amounts of rather smelly gas. It might therefore require particularly tall pipes in order to disperse it with minimum inconvenience to the locals. Sound reasoning?
One of the big questions I then had was with regard to the purpose of the arrow. Arrows are usually directional in nature, telling people where to go, but the height of these pipes make them impractical if they were for use by the public and there's certainly no indication as to what they might be pointing to. The only logical possibility I can come up with is that they actually point in the direction of the underground main and indicate the flow. When I've nothing better to do I might go back and plot their positions on a map and show the direction that each arrow points in. If they pretty much line up I'll feel vindicated. If they point all over the place I'll have to come up with a new theory
I can't really come up with much to explain the other features though. I assume the ball with four funnels must act as a baffle in some way, allowing the gas to disperse efficiently. Could having an open pipe cause a problem if the wind was from a certain direction? The significance of the crown and spike eludes me completely though, unless the manufacturers had a royal warrant or something equivalent. It seems quite a lot of ornate ironwork for purely decorative purposes but who knows?
This seems to be an explainable addition though, a sleeve with what look like ceramic insulators for either electrical cables or telephone lines, I'm not sure which. Obviously defunct these days, it looks as though they've been given a coat or two of rust resistant paint as well.
Who made these wonderful pipes is the next question. I didn't see anything on the first drainpipe, but the second one I spotted on the corner of Weihurst Gardens has a makers mark on the pipe
W. Macfarlane & Co. Glasgow
It doesn't take much searching before you realise that these pipes are the produce of one of the greatest of all Victorian iron works, the Saracen Foundry, the construction of which create the new Glasgow suburb of Possil Park.
Named by Walter himself after a pub by the businesses' original site (The Saracen's Head) this foundry produced huge amounts of decorative and ornate iron work. Their catalogues were mighty, bound tomes and contained thousands of items of all description relating to ironwork and as they employed the most imaginative designers it's no surprise now that the finished ventilation pipe should be so ornate...Macfarlane's didn't do plain! There's a wealth of information on the company on the Scottish Ironworks site, including a gallery of some marvellous examples of surviving works. The foundry was a huge and inviting target for the Luftwaffe in the second world war and at the same time many examples of their work were lost in the drive to melt iron down for the war effort, but they produced so much and spread it so far around the globe that examples like the Carshalton stink-pipes ensure that the company may be gone, but are unlikely to be forgotten.