Underground Clay sewer pipe cracked

[prologica]

Hi all,

I'm in a Victorian country house on shallow foundations - house sits a few feet above road level and often shakes when any heavy traffic passes.

Rainwater runs into plastic downpipes which connect underground to clay pipes that run to some form of soakaway. One of the clay pipes which sits only just below soil level in the lawn has cracked. From what I've read here I think I need to dig around the pipe and find a place to cut out the damaged section then I guess connect a plastic section with rubber connectors both ends to join the clay pipe. Is that correct? And if the pipe is set in soil only, do I need to support the pipework underneath with aggregate of some type, before backfilling the soil? How critical is it to get this right to avoid it cracking again?

Your advice is appreciated. Thanks
D

 

[Ian H]

I would cut the clay after the next joint/collar and join the new piece of plastic using a rubber band seal (google AC4000).

Bed it on 10mm pea gravel, 'chop' the gravel under the pipe with the blade of your spade until it doesn't move when you put weight on it. The you can back fill it and forget about it.

 

[Hugh Jaleak]

Plastic is going to be prone to damage if only just under the surface, usually with shallow drainage runs, concrete is used to cover the pipe and protect it. If you haven't got sufficient height to achieve this then I'd look at using clayware instead. (It may be slightly less vulnerable to damage.)

You'll probably need a disc cutter to cut the damaged salt glazed section out anyway, so cut away enough to accommodate a length of vitrified clay pipe as opposed to plastic. When you're happy pipe is in correct position, (use half brick to support if need be), then surround with peagravel to bed/protect before removing supports.

 

[prologica]

Thanks for the advice Hugh and 1990. Just one question please: If I use new clayware pipe as suggested, is this joined to old pipe with a rubber seal or some other fixing method?

thanks
D

 

[Hugh Jaleak]

Use the Flexseal couplings for DIY. Use of anything else will require pipe lubricant, may need centre stop knocking out to make a slip coupling and without getting exactly the right size, are not guaranteed to fit.

Note: When backfilling try and avoid putting any big lumps of muck or large stones in the intial layer of backfill. Appreciate this may not be too easy given pipe is quite shallow, but you need to give it as much protection as possible to avoid any damage.