Builders seem to have clogged up rain gully

hatt55

My third post of the day! It never rains etc etc.

It looks like the builders who have been doing work at my house have clogged up the rainwater gully, potentially with cement. Its the small grate that the main roof gutter runs into, along with the waste water pipe from a utility room sink (luckily not used very much). This pipe connects into the main foul water drain somewhere underground, so on the plus side at least it doesn't seem to have impacted the soil pipe.

I hadn't been out in the garden much lately but was pouring a bucket of water outside today and spotted it. It looked like it was clogged up with muck, but when I tried to clear it it was solid. Its just about managed to not block water from the utility room getting outside, but anything that actually makes it into the gully just overtops and spills out under the concrete (the yard is concrete, and there is a bit of a void between old ground level and the concrete. On a long list of things to improve).

I've informed the builder and am yet to hear back. They've generally been very good at fixing little bits, but this seems like it could be a bigger job. What should I be asking of them? Do I request that they can a drain specialist to come and have a look? I'd be nervous of them just going at the concrete with a power tool, and feel like it would be reassuring to see that this doesn't extend any further down the pipe…

RAS

Don't let them jet wash it to break up the lump. It'll just cause even more issues.

WIAWSNB

HiHatt. (drrrr-cheeesh! Soz…)

What sort of work have they been doing? And have you been able to remove any of this hard stuff to check what it is?

There's been a lot of rain recently, so is there a chance you just didn't notice it was partially blocked before?

hatt55

They've been doing work that would involve mixing cement - they had a cement mixer, though I wouldn't have expected it to be used extensively. A little bit of brickwork and a little bit of bedding in roof tiles.

The 'plug' in the drain seems very solid. Initially I though it was just going to be gravels and bits washed off of the concrete (the yard is concrete, so this does happen), but it wouldn't move when tapped with a trowel. Its also the case that the metal grate itself had been moved away, as though someone had wanted access.

Was chatting through with a friend last night and they said that perhaps it is just very compacted wash off from the work and I agree that it would seem foolish for someone to have just poured cement in there so that seems unlikely. But it really didn't seem like it was going to move when I was tapping it.

stuart45

Could be it was partially blocked before with gravel and when they've cleaned the mixer and their tools enough cement has mixed in to harden it up.

You have to be careful not to fracture gullys. You sometimes end up renewing them. You don't want it leaking out for years into the foundations. It's a common cause of subsidence.

Boohoo

https://forums.moneysavingexpert.com/discussion/comment/81864500#Comment_81864500

Lift the manhole cover if you can and check to see if there is an cement residue showing.

Don't rely on and trades person not to put anything down a drain/manhole as I have known painters to throw paint down a drain and plasterers washing their trowels in a bucket and then empty the bucket down the drain.

hatt55

Unfortunately there is no manhole visible. I think it may have been covered by the concrete a long time ago.
Yes, my concern is that if its a clay pipe and they try and break this up then it could damage the pipe but I won't know until there is some problem further down the line. Obviously I'll have a chat to them first but my inclination is that I want some assurance that however they remove it hasn't done any damage. Perhaps a CCTV survey after?
Having a look on the internet there are some suggestions that they whole 'joint' can be replaced rather than removing the blockage.

stuart45

You can replace the gully if that's what you mean. In some cases it's easier.

hatt55

Yes, that is what I mean. There must be something a bit more complex under the concrete where it meets the foul sewer and becomes combined, other than just what I can see above. But maybe for a builder with all the tools it isn't that complex - I would be expecting them to sort this out rather than me paying for it.

stuart45

It's not that complex. Google trapped gullys, and you'll see various types. They could be plastic or clay.

Boohoo

https://forums.moneysavingexpert.com/discussion/comment/81864791#Comment_81864791

You should try and locate any manhole covers on your land for future reference. Have a chat with next door neighbour's to see where theirs are.

A CCTV inspection maybe hard to do without access to an inspection chamber/manhole as I think it would be hard to do from a gulley.