damaged drains, difficult site

[10phil79]

Hi - would appreciated any advice.

we recently purchased a house (mid 60s build) and I have uncovered some problems with the drains.

To describe the site: there is no inspection chambers on my property, we share an IC with our neighbours. The main connection to the IC runs from our downstairs WC in a straight line. The IC is about 4 meters away however, the IC is 1.8 meters lower than the wc - the pipe gradients is nearly at 45 degrees!

I've excavated down to the pipe and there is two T joints about 60cm apart providing a branch for RW gullies and a Vent pipe. The main problem I have is the previous owner has "fixed" a blockage by smashing a 4inch round holes in the top of each joint. He'd covered these with broken pipe and backfilled...

i've not finished excavating and exposing the pipes becuase of wet weather but from what I can see, things do not look very good - the clay pipes seem mostly covered in concrete plus the trench is already pretty deep... Replacing the damaged joints looks like a really involved job...

Would having this section of pipe lined be a possible solution?

Any advice would be great
Phil

 

[Hugh Jaleak]

Lining is a solution, although I think it needs a reasonably intact pipe to work. Seen it used when tree roots have become an issue, roots etc are removed and liner offers protection against reoccurance of root entry.

If the pipe is already broken it may allow the liner to deform where the weaknesses in the host pipe are present, which could lead to problems. The laterals would still need to be reconnected too, and as these seem to be where the current problems lie then you may not actually achieve much by lining the pipe!

Personally I would be inclined to replace the pipes, any a mini digger in the hands of a decent builder should be able to expose the existing pipework quite quickly. Remove damaged sections, replace with plastic, peagravel bedding as required and backfill sensibly.

 

[Nige F]

and get rid of that 45 degree fall . should be 1:40 or maybe a backdrop setup or a marscar bowl

 

[digdilem]

I had something very similar - and the cracks from the break extended to two whole lengths of 3' clay pipe. Again, someone had physically broken into a clay pipe and covered over in a mixture of broken tiles, a plastic bag and cement. The cracks were all the way around and sewage had been seeping through for years. Sewage was forcing its way back up as it had snagged on the inside. I was also under a bit of time pressure to fix since I had contractors arriving to concrete over that section in 2 days and I didn't expose the problem until dusk!

Spoke to a drainage friend who dropped me up two "Underground Drainage Clay to Plastic Band Seal Couplers" (Quick google shows them here, but available at all builders merchants: http://www.areco.co.uk/shop/pipe-fittings.asp ).

Expose the broken section and at least 12" either side.

Cut out the clay pipe on a non-flanged section. (Take off the guard and a 4.5" grinder will drop inside the pipe after you've cut out a square for it, and cut right round from the inside very easily - saves a lot of digging to attack it from the outside).

Cut out a section of new 4" plastic (or matching) drainage pipe to EXACTLY fit the missing section.

Slide the connectors over the plastic pipe, then drop into position.

Slide the connectors over the joints and do up tight. (Cordless driver a handy tool here but seriously, DO NOT overtighten or you'll crack the clay. Only go tight enough so that you can't turn the rubber on the pipe.)

Bed around the new pipe with pea gravel to give even support (also makes it slightly less horrible to work in next time you're down there after a failure!)

Backfill and walk away.

(Same technique for cast iron pipe, just different connectors. If plastic pipe, better to just replace a section or use the normal pushfit connectors if you do have to cut)

 

[10phil79]

Thanks all for the replies and advice - appreciated.

I may well be calling in a bit of pro help because i'm getting now where fast. I'm already 5 feet down from the level of my drive and not exposed enough of the pipe to effect any repair...

@nige F - Marscar bowl. Not come across these before - does this allow for a change of height in the same way as a backdrop, but without a brick manhole needing construction?

Cheers!

 

[Nige F]

Exactly that , M8 - be careful in that 5 foot hole