Drainage & old pipes?

[jungle_jim01]

Hi, not strictly a period property question more building...but just looking for a bit of advice. I'm digging a hole to install an inspection chamber for a new soil stack. I've dug in the ideal spot to install this but there are a few additional pipes.
I'm hoping i can lay the chamber in the main hole (lower left of photo), but there are a couple of pipes close to this. I don't have a clue what the old rusty pipe is but if it's possible it would be handy to remove this (any ideas what it could be?). Also the drainage pipe runs directly over the mains water pipe, i'm hoping i can place the inspection chamber in the same position but wondering about bedding it in to ensure i dont damage the water supply and also pass building control?

Thanks as always for your advice.

 

[Lime]

Can't see the picture.

.....and then they immediately show!!!!

 

[jungle_jim01]

should be there now, thanks

 

[Lime]

I presume you are going to intercept the clay pipe, install a manhole and run your new pipe into it at the side?
With modern round plastic manholes I think you should be able to squeeze it in there without moving any other pipe.

An alternative is to cut the copper pipe and divert it out of the way.

Or.. you could put the manhole where your shovel is.

While you are there (in the hole) find out what the other pipes are/were if you can.
If the copper pipe is the mains water you should be able to listen to it (using a straight stick on the pipe and the other end on you ear) when you run off some water.



Be careful of the old iron pipe unless you know for certain it is dead.


Where's the water coming from in the hole?

 

[Penners]

You describe the salt-glazed pipe as "drainage pipe from open trap to combined system". Does this mean that it carries both foul and surface water?

If so, then I agree with Lime that the sensible approach would be to run the old salt-glazed pipe and your new drainage pipe via the same manhole. If the old pipe is currently carrying foul water, then I see no reason why you can't use it to carry your new foul drainage from the new manhole to...wherever... too.

The grey plastic pipe is a puzzle. If it's plastic and gas, then I would have expected it to be yellow. What is its outside diameter?

 

[d49xc]

Old Water pipes will be galvanised steel - which will have rusted depending on the soil conditions
Standard domestic supply would probably have been 3/4" diameter nominal bore - say 1" outside Dia
Don't know whether copper was used bare underground at any time for a supply.
The vertical rusty pipe in piccy looks like much rusted galvanised.

Old Gas will be some sort of steel tube - usually of bigger diameter - say 1" plus nominal so 1.25 to 1.5" OD
This is because old town gas had a much lower calorific value than Natural gas - ie less energy per volume.
Hence it needed large diameter pipes to get the required energy rate into a house than are used now.

Modern Gas underground will be yellow MDPE gas approved
Modern water underground will be blue MDPE water approved

Standard plastic pipe of whatever variety must never be used for gas.
It is possible that the plastic pipe shown is being used as a sheath for running a proper gas pipe inside it.
It is a requirement that gas pipes are sheathed where they run through a wall anyway - so that if there is a leak inside the wall the sheath will ensure the gas flows out and does not accumulate within the wall and possibly the wall cavity.

 

[Lime]

Don't know whether copper was used bare underground at any time for a supply.

That seemed odd to me too.
Old water pipes are either lead, iron or steel usually.
I suppose it could be a gun metal of some sort.

How was the copper pipe placed where it was?
Those of you who have installed stiff pipe will realise it is very difficult to put in when weaving through other pipe lays.
Its right at the bottom of the pile.

 

[jungle_jim01]

Googling this there's a few other forums with people mentioning copper mains water pipes. I'm going to try the gas company tomorrow and see if they will check that the grey pipe is disconnected. Still confused by the rusty one though ...it would be much better layout for the manhole if i could chop it.

 

[jungle_jim01]

Thanks again for your advice. I've been having another look and located both ends of the gas pipe which are totally disconnected. The rusty pipe has a 5mm hole in it and nothing leaking so that must be redundant and the copper water supply is 22mm so good news! I can crack on with the digging.

Like i said before i'm going to be installing a new soil pipe and inspection chamber. I'm very much a novice at this so just taking it slowly but any tips & suggestions on installation and satisfying building control would be very much appreciated, especially any info about required testing?

thanks again.

 

[jungle_jim01]

1 more question: does anyone know if the IC needs to be a minimum depth?

 

[Penners]

JJ - the following web page is a mine (ha-ha!) of useful information about manholes and all matters related thereto:

http://www.pavingexpert.com/drain05.htm

 

[jungle_jim01]

Thanks for the link...great site!