Advice wanted for a thirties drain.

[ukdodger]

I'm laying a new patio but as it is going to be lower than the old patio I have to lower the drain. Sounds simple enough but digging down to get at the soil pipe this is what I've come across. It looks like the pipe is held in a concrete shroud. Does anyone know if that was common practise in the thirties, and if so does anyone have any ideas how I could get at the pipe without first filling the drain with concrete?

http://i.imgur.com/ue8qnRI.jpg

 

[nickjb]

My 1930s drains had a bit like that. I dug the lot up and replaced with plastic. Every bit of clay pipe I exposed was cracked (and had been for some time so it wasn't me!) I though it was better to put new in before covering it up.

 

[ukdodger]

My 1930s drains had a bit like that. I dug the lot up and replaced with plastic. Every bit of clay pipe I exposed was cracked (and had been for some time so it wasn't me!) I though it was better to put new in before covering it up.

Thanks. But how far did you have to go to make a join. The manhole here is in my garden and about 10ft from the drain. Would it go right up to the manhole?

 

[ree]

Pics showing more of the elevation would be helpful. Plus a pic of the position of the man hole in relation to the RWP.

How far below the door cill: do you want to dig out, and where do you want your patio FFL to be?

Is that a temporary board and door or is it permanent?

What is the metal access cover for?

The salt glaze hub should be eliminated and a trapped gulley installed.

You will probably have to remove all the encased drainage, and relay new drainage. Cutting the encasement and pipe is easy enough but cracking off the concrete will probably shatter or hairline crack the exposed stub of pipe which is necessary to make a connection.
Anyhow, any change of drainage depends on how, and where, the new pipe will enter the man hole - a pic down the manhole would help.

To the right of the pic the brickwork drops lower to GL, and a sand and cement plinth can be seen:
1. the plinth should be removed.
2. is there a serious discrepancy in proposed patio FFL and exterior GL?

 

[Beefpotnoodle]

Just doing the same job as this at my house, drain was broken at top two joints. Had the concreted joints go somehow too! I had to dig about 2m down and out to get back onto a good clap pipe. Tracking back to the main drainage junction isn't feasible at mine, its be about a week of digging. Be sure to keep a decent a drop on the new pipe, I've added a rubber connector to join new plastic to old clay

 

[Beefpotnoodle]

And to avoid filling the pipe with concrete I cut a section out below the joint, then with the section removed bunged up the hole so I could smash out the concreted rubbish!

 

[bernardgreen]

Encasing broken / leaky drains in concrete is a quick fix method to "repair" the drains used by bodgers.

I would have the drains inspected as that concrete may be the thin end of a wedge of a bodged repair / installation.

 

[TheVictorian]

If you have the time and the energy then it is beyond doubt that replacing it with new all the way to the manhole would be the best long term option.

 

[ukdodger]

If you have the time and the energy then it is beyond doubt that replacing it with new all the way to the manhole would be the best long term option.

Thanks. Sadly I have a feeling that that is going to be the only option. I've decided to dig backwards toward the Manhole hoping to see if the concrete ends leaving just the clay pipe. But if it goes up to and maybe includes the manhole I think I'm well and truly in the brown and smelly.

 

[ukdodger]

Hi and thanks. The door is permanent. The top of the new patio will be level with the concrete base of the garage seen on the right behind the yellow hose nozzle. The drain itself is only for waste kitchen and bathroom water not rainwater.

The metal cover is for inspection only. Water comes in from the right of the cover and tips into the drain outlet which is vertically in line with the cover. Cant get a pic under the manhole cover but I know the entry into the manhole of the pipe is about 2ft down from the lip.


http://i.imgur.com/saabhtJ.jpg

 

[ree]

Definitely dig out and replace the short length of drain pipe - its simply not worth messing about cutting and connecting under a new patio.

First establish the finished height of the new gulley, and see if that will give you enough fall to re-use the inlet into the manhole.

The proposed patio surface in line with the garage concrete will give you a very high riser step-up into the kitchen - 7 1/2" is a typically Blg Regs required riser height.