Report - - Misc Drains, North London July 2020 | UK Draining Forum | 28DaysLater.co.uk

Report - Misc Drains, North London July 2020


more tall than ginger tho.....
Regular User
Having walked the length of most of the storm reliefs and lost rivers I thought I'd take a look at some of the bigger pipes that make up London's drainage system. Bazelgette is famous for designing and overseeing the construction of the Interceptors, which on both sides of the Thames flow from west to east to the pumping stations and sewage works, intercepting all the sewers that used to pollute the Thames. Generally you can't walk in them as during the 'waking' hours they're far too full and fast flowing but in the very early hours it gets a bit easier. There wasn't a great deal of walking involved as most of them are quite featureless for long distances. Usually, it was a case of going in and out of the same lid

Mid Level No.1 - Farringdon

Some of you may remember a report I wrote ages ago about an interesting part of the Mid Level, where it interacts with an odd by-pass pipe, the Fleet Storm Relief, the Fleet and the Metropolitan railway. I didn't know about the by-pass at the time and couldn't really see the Aqueduct because I'd gone too early and there was too much flow. The Fleet Storm Relief was built after the Mid Level was so I can only assume the bypass pipe was used (possibly in conjuction with the Ranelagh Relief on the mid level) to bypass the overflow/ drop shaft connection to the Fleet Relief while it was being built. It's not particularly exciting and has now been bricked up. Just upstream is where the Fleet Branch of the Mid Level joins. I must've seen it but not photographed it. Dunno why - maybe it was too slippery to bother setting up a tripod......

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Overflow to Fleet Relief and dropshaft. Apparently TW or their subbies didn't check the weather or forgot their youngman board one evening. Somehow, I suspect this is supposed to be at the top of the shaft with the rest of their kit. I couldn't even see this shaft from above last time as the grill was so covered in rags. Perhaps it was reducing the effectiveness of the overflow and this is why they were doing the work.

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Looking upstream towards the other end of the by-pass section.

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The overflow to the Fleet CSO on the right just before the aqueduct over the Metropolitan Railwway

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Behind the penstock on the right is a very confined chamber with all the penstocks workings and a steep, cast iron / brick slide which drops into the fleet sewer

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The Mid Level Sewer is carried over the Metropolitan Railway by a wrought iron aqueduct of 150 feet span, weighing 240 tons; the depth of construction between the underside of the aqueduct and the inverts of the double line of sewers being only 2 1/2 inches. As the traffic of the railway could not be stopped during the construction of the aqueduct which is only a few inches above the engine chimneys the structure was built upon a stage, at a height of 5 feet above it's intended ultimate level and was afterwards lowered into place by means of hydraulic rams. This stage was necessarily of great strength and was carefully constructed, the sewers being formed by wrought iron plates riveted together
Aqueduct on the left

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This is looking upstream through the aqueduct. Arch on the left leads to another original overflow into a 4ft pipe. This follows the railway for a short distance and i suspect it leads to the Fleet. Arch on the right is just a local sewer IIRC and the square opening on the right is a concrete side entry

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The Low Level No.1 at The Embankment

A surveying company had the privilege of surveying every part of Blackfriars Bridge (Fleet Storm Relief not shown :( )


First up this is not a place to get caught out. Most of the lids downstream are heavy split lids. If it's rained in the passed few days, the tide's in, it's the weekend or 'not very late yet' don't even set foot foot in it - wait till tideway's done ;) In fact just don't set foot in it at all

This is a short distance upstream of the Fleet (so part of JBizzles Victoria Embankment) and I've no idea what it is. Does anyone else?

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Tree roots penetrate the gully pipes in search of water. Every gully by the looks of it. Rags collect on the roots.

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A familiar penstock to anyone that's walked the corridors at the end of the Fleet / Storm Relief. The two Fleet pipes which cross the Low Level are visible just a bit further down

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This section interested me (as you might expect). The majority of JB's interceptor scheme was complete by the late 1860's, the only thing that wasn't complete was the Low Level No.1. This was because it was decided to built it alongside the Thames Embankment, itself a massive undertaking. The River Wall had to be built, the swampy Thames bank drained, ballast brought in, the District Line built, the utility tunnels, the roadway and the arches that it's built on, the public gardens, everything! It was started in 1865 and wasn't completed until 1870. I came across this site which give more detail on the construction of the Victoria Embankment https://wondersofworldengineering.com/embankment.html

At this point, moreover, the subterranean engineering has been of extreme complexity; the sewers, the Fleet ditch, the subways, the Gas Company's railroad, the public railway, and a variety of gas, water, and telegraph pipes, being interlaced in a way that almost defies description........The level of the rails is generally 17½ feet below the surface of the road, which is carried over the railway by cast-iron girders and brick arches, the upper surface of the arches being 18 inches below the surface of the road..........It is not easy for persons unaccustomed to deal with such matters to form any clear conception of great quantities expressed in numerical statements; but it is, nevertheless, worth while to place on record the official accounts of the cost of the work, and of the amount of various kinds of material employed in its construction. The total cost is estimated at £1,260,000, and the purchase of property at £450,000. The quantities of materials are stated to have been as follows:—Granite, 650,000 cubic feet; brickwork, 80,000 cubic yards; concrete, 140,000 cubic yards; timber (for cofferdam, &c.), 500,000 cubic feet; caissons (for ditto), 2,500 tons; earth filling, 1,000,000 cubic yards; excavation, 144,000 cubic yards; York paving, 125,000 superficial feet; broken granite, 50,000 superficial yards
Blackfriars Bridge (which replaced an old one built in the same location) opened in 1869. You kinda have to know the area around the Fleet outfall to fully understand but the first arch starts above the road (not the river) The rather lovely brick chamber at the end of the Fleet Sewer / Storm Relief is further inland than you would expect so it could discharge straight to the then adjacent Thames / old Fleet Estuary through the bridge abutment. The sewer was extended in the 1960's when the roadway and realigned river wall beneath the bridge were built. What surprised me is that all the brickwork in the Low Level is the same and they appeared to have built the whole lot in one go. No part of the Interceptor, at least, appears to have been rebuilt, cut into or added to in anyway.....So they knew the Fleet was going to need a storm relief before the Low Level Interceptor and the Embankmnet were complete.......Maybe that's why the bypass section on the Mid Level looks so neat as well because they'd already planned to build the Storm Relief.

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The interceptor is wider here to make up for the reduced height. The Fleet Storm Relief is the one closest to me. It was constructed between 1872 and 1875, much earlier than most of London's Storm Reliefs.

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Where the flow from the Fleet sewer goes. This was a lot smaller than I expected. Most of the connections to the Low Level are this size whether they come from a big lost river or a 4ft local sewer.

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I went back to the penstock and climbed up to take another look at the Fleet. Flow goes down to the right and into the Low Level just the other side of the short weir wall. The area with the yellow brick is directly above the Low Level Interceptor. I'd not noticed the concrete patch and the red bricks on the left on previous visits. The storm relief is just the other side of that wall

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The Fleet was practically empty and what was flowing in it was very clear

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Some of these are old pics, taken on a visit with @Conrad showing the outfall chamber where storm flows from the sewer and storm relief combine.

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One of two brick pipes leading to the Thames - the 60's extension?

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From the other pipe but looking back up towards the enormous flaps and tumbling bay. The white sticker on the Steel plates reads "PROPERTY OF LONDON UNDERGROUND IF FOUND PLEASE CONTACT OUR NETWORK OPERATIONS CENTRE ON........".

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Low Level No.1&2 Balancer Chamber

After checking a few other drains I went to see if I could find the first balancer chambers between the two Low Level Interceptors near Mansion House. There's another one further downstream and two similar set ups between the 1st and 2nd Low Level Interceptors South of the Thames. My understanding is that they can balance each other out if one is substantially higher than the other. Penstocks are provided in all three directions so the downstream flow from one Interceptor at a time can be completely shut off. Being quite confined the counter balance weights, chains and pulleys are arranged in quite a photogenic way. It sounds obvious but before the Low Level No.2 was built there was just the original Low Level No.1 here. The Low Level No.1 is built of yellow Gault bricks. The blue and the red engineering bricks were laid by the LCC in the first decade of the 1900's when both of these chambers were built.

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SWC | Bally up!
Regular User
Standard of reportage is very high here, as one would expect! Hope you’re well mate :thumb


Loyal to the Drain
Regular User
Legendary report as per usual sir!
Quite a few photos there showing parts of the network that I've never expected to see.
I recognise the dropshaft down into the Fleet SR. I took a pic from the bottom when we were down there in June, it was a long walk we had that day.
Didn't think I'd ever see where the Fleet is finally intercepted by the Low Level from that side of the wall. :thumb
Can't wait to get back out there when we are finally allowed, so much catching up to do ffs.



more tall than ginger tho.....
Regular User
Thanks guys, pleased yers enjoyed it. Yeah all good thanks @tarkovsky hope you are too. Thanks @stoff urbex yeah walking in his footsteps and he'd have been very busy round those parts. Thanks @TheVicar thought you'd recognise that shot of the storm relief. Must admit i didn't expect to see the fleet from the low level interceptor either but i didn't know what to expect tbh. Glad i did tho


28DL Full Member
28DL Full Member
Thanks for this TG, I live vicariously through your posts, especially in these very strange times, let us hope things get back to normal so more explores and meet ups can happen, I do like the infrastructure that you unearth (pardon the pun!).



28DL Full Member
28DL Full Member
Fantastic report! I do look forward to seeing new drains stuff from you. In depth history and linking the details to the overall 'vision' of London's sewer and lost river systems, top stuff. Thanks for sharing. :thumb


more tall than ginger tho.....
Regular User
Thanks for this TG, I live vicariously through your posts, especially in these very strange times, let us hope things get back to normal so more explores and meet ups can happen, I do like the infrastructure that you unearth (pardon the pun!).

Thanks pasty, glad yer like 'em and yeah sooner we can get back outside the better :banghead

Fantastic report! I do look forward to seeing new drains stuff from you. In depth history and linking the details to the overall 'vision' of London's sewer and lost river systems, top stuff. Thanks for sharing. :thumb
Thanks yeah drains need the bigger picture explained a bit, especially in London. For something as simple as allowing water to flow downhill the individual parts of the system and how it works around other infrastructure can seem very complicated. Nowhere more so than at the end of the Fleet where there's loads happening in a relatively small area. Imagine being the person responsible for building it, having all yer designs in yer head and getting to watch them all being built from start to finish all over town

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