Pipe Bingo - what's what?

[wuptdo]

I dug a test hole today to prep for some work later in the year (drain depth etc.)

However I stumbled upon a few other pipes in the process...

The brown pipe is the clay foul drain I was looking for.

There is a silver metal pipe in the top of the image - this had roughly a 32mm OD.

There is black plastic pipe to the right of the image - this had roughly 25mm OD.

Its unlikely these are water unless they're old and disused as I know where the water pipe runs and it's 1m away.

I have a feeling they are the gas pipe(silver)and a ducted electrical cable feeding the garage(black). Are older gas pipes typically metal? House is 30s build.

Extra info which may or may not go against my 'theory':
-The black pipe is running directly towards the location where a 34mm OD (black) gas pipe comes out the ground into the meter. This goes against my theory.
-The black pipe is also in line with where the electric cable comes out of the ground in the garage. This supports my theory and it may just run into the house at a similar point to the gas main coming out of the ground.
-There would be no purpose for the silver pipe to run right to left. This would not intersect with my house or garage, it would run from neighbours garden to neighbours garden. If it is not the gas pipe I have literally no idea what it could be!? potentially an old & disused water main? I expect it could be part of a large radius bend in the gas pipe (so it appears straight).

Thanks Wuptdo

 

[wuptdo]

Looking closer at the meter 34mm black pipe inside the meter... Its actually a 32mm metal pipe. The black coating appears to be 1mm thick.

 

[JohnD]

The "silver" pipe looks to me like lead.

 

[Hugh Jaleak]

Silver pipe, suspect is Lead, water supply, may still be live, don't assume anything! Black plastic would also very likely be water. Gas would either be steel/malleable iron or yellow plastic.

 

[wuptdo]

Hmm interesting. So my original intention of digging here was to investigate drain depth in 'easy soil' prior to digging up for drainage works under the concrete driveway. I am reasonably confident that the black pipe here in the original image is not water, so it's highly likely to be the electrical conduit. The conduit running out of the floor in the garage seems similar in terms of material and size. So at least we've resolved one mystery.

However you've now peeked my interest about the lead pipe potentially being for water...I do have a 'rising damp' issue (intentionally using quotes here) that I'm trying to resolve. I suspected as the water main coming into the house now was plastic, that this was unlikely to be the issue. I did not think about the fact that the old pipe could potentially be live and leaking...

When I drilled into the course of bricks surrounding the perimeter of the patio to affix a post, water literally 'poured' out like a fountain. I just put this down to clay soil and having no where for the patio to drain...

Even though these are semi detached properties, it's entirely feasible that they all originally shared a common water main down the rear of the houses - as they were originally council houses. This could run on to my joint neighbour / and or be simply 'poorly capped off' in my house.

See below diagram for detail (note the blue / dark blue water main is black plastic) and has clearly been retrospectively installed. I expect it does a large radius under the concrete in front of the garage before heading down the driveway.

I think I may ask Cadent if lead gas mains are feasible...this will help narrow down things before I start digging up the patio looking for a leaking lead pipe.

 

[Hugh Jaleak]

I have never known of a Lead Gas pipe underground, it was, (to my knowledge), all done with cast iron mains and steel service pipework to the ECV, with some Lead used inside the property, until plastic took over.

Water is a different issue, water services were traditionally done in Lead, with a good many still in use. Given the fact you mention some of the property's history, there is a good chance you may find the original water supply was teed off a shared supply, which, over the years, as demand for water increased, became more of a problem with Occupants finding themselves with little of no pressure/flow at peak times when there was a lot of demand. People then proceeded to have independent supplies put in, but often the old lead supply was just capped at a suitable point, often leaving a long dead leg.

You may even find, the 'capping' was done using the old method of hammering the Lead flat, and bending it over double, before hammering it some more. Invariably these stayed dry for long enough to bury the pipe, with many leaking thousands of gallons of water out over the years. Had one in a Friends Garage, which was a repurposed brick 'barn' that formerly housed an outside WC. Digging the floor up to put a drain in to refit a Downstairs Cloakroom, we quickly found water, and a lot of it. Soon turned out the former supply to the original WC, (lead pipe) had been hammered flat to 'seal' it and had been leaking, for well over 20 years probably.

 

[wuptdo]

Hi Hugh, thanks a lot for that - really informative.

Looks like I might be digging up the patio soon...will update this post with any findings.

Will first wait to hear back from Cadent though re lead gas pipes and update you with their response.