Old house, rainwater drain in pieces

[Kaymo]

First pic below shows the corner outside wall, where main wall on the left meets protruding wall from the porch, black downpipe is from the rainwater collection from the flat roof of porch. House is down has being ~1885, but I suspect that this was just when the porch and bay section was added and I think the house is older, maybe ~1820.

I've been concerned since moving in about the dampness on the wall you can see on the right, and I dug this out today to find that the bend is just butted up against the underground straight section, and then as seen in the next photo with it all out you can see that this was butted up against another short straight section that is a completely different size. I suspect water has been seeping out between the bend and the first straight piece over a long period of time and saturating the ground and the sandstone wall in that corner, causing the damp at the bottom of the wall on the inside.

The sections I have taken out amount to about 1.5m away from the wall, then I stuck a drain rod in which went about 2-3m before stopping. I was concerned it might be blocked or terminated but I stuck a hose into the drain and left it running for 5 minutes and didn't get any water coming back so it must be going somewhere.

Any advice about what the best thing to do here would is appreciated. Obviously I want to seal this up, not sure what the best way to approach this would be though. Was thinking probably to try and get a new plastic pipe to fit between the bend and the piece that is still in the ground but not sure about the best way to connect and seal as I have never done anything with underground drainage before. Not sure whether I should dig more of the drain out, but as that would probably involve lifting the path it goes under was hoping to avoid that and it appears to be taking the water away ok.

 

[Ian H]

The piece after the bend is backwards and missing it’s collar, must be a bodge up from some point in time.

Then after that the pipe looks black, could it be pitch fibre from the 60’s? If your water runs away you could be hitting a junction with your rods.

If I were i’d buy a 4D900 gully, a length of pipe and an AC4000 plastic to clay connection. Join that onto the black pipe and monitor it for a while.

 

[Kaymo]

Sorry Ian, the black pipe is the painted cast iron downpipe, its just upside down in the bottom pic because of the way I laid it out on the ground. The black downpipe goes into the 90 degree bend, the lighter grey part of which was above ground. The bend was just butted up against the clay pipe. Its definitely been a botch up, I suspect its been done when the driveway was added probably around the 80's and they seem to have just butted random, different sized pipe up against each other and just pressed the soil around the joints!

Thanks for the parts, just the terminology helps (I didn't realise the open drain was called a gully). The 4D900 one that I found seems a bit bulky for the space but on the same site there were other, slimmer gully's that might be better for that corner.

I put the downpipe back on and left in a bucket last night. This morning with a bit of light rain last night the bucket was nearly full. A lot more water than I would have thought from that small porch roof, and a good portion of that being funnelled under the house for probably the last 30 years!

 

[Kaymo]

I've taken another look at this in daylight, and it seems that the small piece of pipe on the rightmost in the bottom pic is not broken, but is what I think was called a drain tile and is the same as the sections that are still in the ground. Its flat on the bottom and is slightly oval in shape, 67 to 79cm internal diameter, so its unlikely that I would get a very good seal to round PVC pipe even with a flexible connection. I did a bit of looking up on the internet and I think these tiles were simply laid in the ground butted up against each other. I suspect that some time in the past some of these have been broken near the house and someone has laid the big section of round clay pipe up against one end, then the cast iron bend from the downpipe up against the other end of the long section.

I am starting to wonder if a better option in this scenario, might be to push a one piece 50mm flexible pipe as far down the existing drain as it will go, and connect the other end directly to the downpipe. The downpipe is open at the top so there should be no issue with any pressure or gas build-up, and it would probably have a better chance of being sealed, with the old pipe still around it for a bit of protection. Its only a porch maybe a metre or so square, so 50mm should be enough for the flow, and the downpipe itself can't be much more than that anyway.

Any downsides to this plan?

 

[Ian H]

It might work but I wouldn’t.

With a gully you catch any silts before they go down the drain and if the drain blocks you will see the gully overflow. The band seal should fit over the oval pipe, the joint won’t be perfectly aligned but it will be watertight and get the water further from the property.

With the 50mm flexi pipe joined to the downpipe, if it blocks first you will know is when yours gutters over flow.

You could try it though, it could work for many years.

 

[Kaymo]

Thanks Ian. I'd prefer the gully set up, my concern is that these clay drainage tiles, which are only about 1 foot in length, could be seeping water out at the next or the next again connection, and the only way to be sure would be to dig the whole thing up, which would be quite a substantial job. I don't even know if this pipe connects into the main drain or is buried in the garden somewhere. The flexi pipe might even be a good temporary solution until I have the time to do something better.

 

[Ian H]

If you do that i’d push it in as far as you can, then pull it back by 150mm before you seal it. Just in case it is hanging into a junction.