Report - Holloway Storm Relief (Heavy Mettle) 2012-2018.

[Ojay]

Holloway Storm Relief (Heavy Mettle) 2012-2018.

Heavy Mettle is the Holloway Storm relief, running West to East across North London. It intercepts with the North Eastern Storm Relief at it's mid point (Deep Ochre) as seen in the above picture ^

It's original terminus was the Northern High Level Sewer, but modifications were later made by the Metropolitan Board of Works and the LCC (more of that later)..

There was no separate system of sewers in London for dealing with the surface water apart from the sewage

Based on a report from 1878 by Bazalgette, referring to the ongoing problems with rainfall The Metropolitan Board of Works decided in 1879 to carry out a number of relief works at an estimated cost of £708,000

This included construction of a storm sewer estimated at £64,000 to relieve Holloway and Kentish Town and was the first step in flood alleviation within North London

In 1903, when, during June, July, August and September, the rainfall in London was exceptionally heavy, and many places were flooded that had never been flooded before

On the 19th November, 1903 the Main Drainage Committee submitted a further proposal that large additional flood-relief works should be undertaken

A total of 9 works were adopted by the LCC on the 16th February 1904 at an additional cost of £737,000; to include top of the list a storm relief sewer from Holloway to the Thames

In 1920, principal flood relief works carried out by the Metropolitan Board of Works, included an extension to the existing storm relief within the Hackney area

2007 was the last we saw anything properly from this place when Jondoe covered a good stretch of it, most of that is no longer available online sadly

I remember reading JD's account of his and St00p's trips down here, also tales of the North East Storm Relief and the Holloway going berserk for no apparent reason from others

To quote the main man himself, "Heavy Mettle name came about due to the section from the O RLY junction heading downstream being mostly a relentless slog through knee deep sludge and silt"

He wasn't wrong, and now over a decade on it's much worse!

>>Fast forward a few years and I'd dipped my toe into some of this lot on occasion, but never made much of an effort to figure it all out until more recently..


Now I've played this old chestnut before, but here's what can happen WITHOUT the presence of rain down this lot when presumably the Northern High Level Interceptor can't cope!

When it rains eh

Where does it start/end was my original question ?

Well, I always believed that the start of the Holloway Relief was a point in which the Northern High Level Interceptor interacts upstream

Despite "not being a great couch guest" that night as described by GE066 it wasn't infact the CSO we originally looked at in 2014 as seen here

Instead, the start point lies below an unassuming manhole further upstream in Upper Holloway which serves the local sewers..

Heading downstream from the High Level CSO, the Holloway is largely a 7ft RBP which continues in an Easterly direction towards the Emirates Stadium

There isn't really anything to see apart from a short connection added during the regeneration of the area surrounding the Emirates which I don't have a pic of sadly

The next notable feature is known as O RLY, this is a junction where both the Holloway & North East Storm Relief intercept one another

It's pretty unique and my age old Samyang special doesn't do it any justice really

The next shot is looking downstream (East) standing in the the Holloway Mainline on the left, you can see how the North East Storm Relief intersects

Continuing downstream towards Newington Green it get's a bit slippery under foot

They can't build houses out of brick that last a decade these days, let alone a few Bazalgette beards worth than this lot

And then comes the silted/grotty section, I packed up not long after this shot as it started to become quite grim around 100m further down..

The next feature is a bit of a mystery really. Here the 7ft RBP splits into two smaller diameter pipes (Under 5ft) for approx 250m

Unless there are some utilities in the way I can't explain why the need to split the system for such a small stretch, hopefully someone one day can shed some light on this as I'm baffled ?

Plan B here was to drop back in after the split as I'd already concluded the run up to it was pretty shitty and seemed a lot of effort for little gain

Our manhole of choice was not to be as Ginge had made a right racket lowering the nearby knackered lid and we had to swiftly leave as Mrs Brown wasn't too happy with us hanging about her prized wag mobile

Luckily I'd managed to suss a way in about half a mile away, a spiral staircase drops down a good 10m to the festering stinkhole below!

(I didn't even fetch the camera out)


If it's shite, black & white

Turdtastic!

I did question at this point what the hell we were doing bent double in what was a proper shit-fest of a 4ft pipe attempting some pics whilst the meter was hinting at us to leave

pic c/o Ginge


This flooded 3ft cross passage leads to the other side of the split and no doubt serves as a balancer

Here's what you could have won if you slogged that half mile upstream on the previous bit, f00k that!

We decided to abort walking down the final stretch of the split, as the amount of detritus being churned up was giving Ginge a headache and I wasn't feeling it much either

Shitty phone pic or it didn't happen.. Even the bounty was hanging on for dear life

*EDIT

I couldn't resist nipping back after I'd written this lot up, as I really wanted to see the elusive 'split'

From West to East, it's a grim traverse for a couple of average pictures, although I shouldn't have turned back on previous trips!


Here the familiar 7ft RBP appears to have been re-enforced with spray 'crete for approx 20m or so..

Above ground is Aberdeen Park, an old 1860's private estate with a church ahead of the split, one can only assume strengthening was a necessity here ?

PIC


Further down, 'THE SPLIT'

PIC


Heading downstream in the general area of Highbury it doesn't get much better; comprising of mainly hardcore silt and the occasional fetid standing water, it wasn't a pleasant stroll!

It's almost like you have to walk forever in here before you stumble on anything worthwhile...


The next feature is a relief for the London Bridge Sewer Balls Pond Branch (Northern section)

Essentially a 5ft RBP (date unknown) that has been bolted on to further alleviate the system at capacity

Pressing on past Newington Green it gets a bit easier as the invert level starts to work in our favor

Anyone with a keen eye will notice the Stoke Newington Branch extending from the Mainline on the LCC Map down to the London Bridge Sewer

Here a CSO in the form of a 4ft egg serves 3 smaller trunks upstream of Stoke Newington

Upstream the 3 sewers converge

Back in the Holloway, we soldiered on downstream through the silt & stench a good 15 minutes which would essentially have taken 5 mins topside

The target being another connection to the Balls Pond Branch (Northern Section) of the London Bridge Sewer, sadly I only managed a couple of crappy phone pics here..

The 3ft RBP leads to a walled CSO that serves the LBS, just outta reach even for a Tallginge!

Heading East is a decent slog before reaching the end...

well almost

​

 

[Ojay]

Here's where it kinda got confusing from behind the keyboard, even having read JD's previous account of the next bit it was still a head fuck!

That's the thing with drains, you really have to see this sort of stuff up close and personal or you simply won't get it no matter how best anyone tries to explains it..


I sorted a way in slightly upstream of what is officially the end of the Holloway Storm Relief

Our lid of choice was rather bait, a turn of the corner down a tranquil street in Hackney Downs presented itself with what looked immediately like the Bronx on the first visit

There were more dealers here per square mile than sewers

On a later trip here, we were chased down the lid by some screaming bag head off her tits at stupid o'clock, luckily I had the GoPro running on that occasion!


At The End is this 'Stepped Chamber'

On the left, (and ahead) despite any lack of scale is the continuation of the 7ft Holloway Storm Relief which originally terminated within the Northern High Level Interceptor which runs behind the truncated piece with the dam boards

On the right, is the 1920's extension of the Holloway Storm relief, see below for more of that...


From the stepped chamber, Ginge and myself wrestled with the dam boards in attempt to get a look behind at the High Level Interceptor with my iphone

How the hell I managed to once walk down that death on a stick without dying.. Never again!!

Back to the chamber, we turned our attention to the Holloway Extension added by the LCC as part of their principal flood relief works in the 1920's

Here's looking back up the original line of the Holloway from the 1920's diversion chamber

From here, a 6.5ft RBP heads East, downstream towards Hackney

Just when you think you've seen it all, an abrupt end with a poo slide

Nope, we're not done yet, beyond the dam boards, is a continuation of the Holloway extension, more pics of that to follow further below..

Turning our attention to the 'poo slide' on the right, you will notice there are weir boards at the top

This is the start of the High Level Relief that serves the Northern High Level Interceptor which runs perpendicular (almost)

Here is another snippet from the LCC map which shows this lot merge

Note the varying tide marks, it also acts as a reverse weir from the Holloway and a stilling pond when at capacity


A laddered walkway allows access to the High Level Relief & Sewer and the top of the poo slide approx 3m above the Holloway

Top of the poo slide, looking back down to the Holloway extension

A wider view of the chamber from above; the Northern High Level Sewer lies beyond that hefty wooden flap of doom

Naturally we went for a peek behind said flap.. A short passage way leads to a small CSO with a single sided weir allowing the Interceptor to overflow into the High Level Relief

(Moar shitty phone pics)

"I'd say mostly you'd do your best to stay well clear of the Northern High Level Sewer/Northern Outfall, unless of course you have a dinghy and a death wish!"

Jondoe.

4 years ago we diced with death upstream from here in the Northern High Level Sewer, won't be doing that again

Contorting back from behind the wooden flap of doom, spill flows from the Northern High Level Interceptor curve downstream and into the High Level Relief

Around the corner, this 7ft Pill shaped brick pipe marks the start of the High Level Relief which runs down to Bethnal Green and eventually joins the North East Storm Relief near Shoreditch High Street

Tideway Proposal

In an average year the Holloway Storm Relief combined sewer overflow discharges 7,900m3 of untreated sewage into the tidal Thames at London Wharf, Limehouse

On the basis that litter tonnages are proportional to discharge volumes, approximately two tonnes of sewage derived litter is also discharged in an average year

A work site is required to control the Holloway Storm Relief and divert flows into the Northern Low Level Sewer No.1 and transferred to Beckton Sewage Treatment Works, via the existing sewerage system avoiding the need to connect the CSO to the main tunnel

A penstock and flap valve chamber would be constructed to allow the introduction of a control gate within the sewer which would appropriately divert flows when required to control the CSO

The only mystery for me was with Heavy Mettle/Deep Ochre is the fuq does this go from the High Level ?... I've since answered the question, just need a suitable way in now

Draining comes at cost, myself and @tallginge have spent a small fortune in the Coronet on the tube and night buses

Speaking of which I'm sure Ginge and @TheVicar will be along at some point with more pics of the Ratcliff stuff they have been on with...
​

 

[little_ boy_explores]

great report @Ojay

 

[Exploring with Andy]

I usually find these things to be just a bunch of nondescript tunnels, so I enjoyed reading your commentary here. Nicely assembled mate.

 

[Lenston]

Top stuff mate

 

[tallginge]

Fantastic report mate and smashing pics Yeah took a bit of figuring out how the high level, the ratcliff, the holloway extension and the high level relief all work together in that area Its simple but incredible engineering thats still working very effectively. Good times down there between the typical british bad weather we've had. Where's next!

 

[Ojay]

Where's next!

Spoons

 

[Polominto73]

Cracking report matey don't normally look into these a lot but the amount of time and effort yourself and your fellow subterranean explorers spend deserves full recognition from us top dwelling mortals well done and thank you for providing us with your worthwhile and worthy reports

 

[tarkovsky]

Nice one! Some really nice detail and great photos.

just outta reach even for a Tallginge!

Haha! If a Tallginge can’t reach it then nobody can reach it.

 

[mockney reject]

That is an ace report!

Cracking pictures @Ojay


Soooo pretty but sooooo not for me lol

 

[Camera Shy]

Great read and snaps there !

 

[FreshFingers]

Filthy boys.

 

[TheVicar]

Nice report and pics there Ojay!
It's good to read some history regarding these drains, just a pity there isn't more easily available as I could read it all day long. I guess drains aren't sexy enough for historians to spend as much time on as other things.
That LCC map is rather nice eh? Shame it isn't as detailed as the bigger one, but that wouldn't fit on the average bedroom wall.
Those little three 'eggs' in the Stoke Newington Branch are lovely, but have not seen those myself.
I'll be getting a report up on the Ratcliff before long when I get a moment to sort out my photos.

 

[tarkovsky]

I guess drains aren't sexy enough for historians to spend as much time on as other things.

I think it’s actually coz they’re too sexy for historians. :

 

[TheVicar]

I think it’s actually coz they’re too sexy for historians. :

Yeah I think you are probably right about that!