House Drainage Puzzle

[GE90]

Hi Guys, a little puzzle!

Any chance someone might be able to help with a drainage issue please? I have set out my investigations on the plan.

Right, so the issue is that, when raining, the garage channel drain and the roof downpipes drain both overflow. When is stops raining, the level of both go down at the same rate, so must be connected.

So, I lifted main chamber (foul) and saw a pipe going into it. Although I understand surface water should not drain into it, there was a drain higher up that I thought might be the roof and garage drains. However, I have traced it back to what is shown as the redundant pipe, under the drive.

Any thoughts on what I should be looking at next? I put a flex pipe inside the pipeline leading from the garage drain, and show an arc of where it reaches. Should this connect to something?

Thanks very much.

 

[23vc]

When you pour water down the garage/downpipe drains, do you see it flow past in any of the ICs?

 

[GE90]

When you pour water down the garage/downpipe drains, do you see it flow past in any of the ICs?

Hi, no. I tried with the pipeline from a jet washer, both from the garage and downpipe, and cannot see it flow anywhere I'm afraid. It just fills and overflows both at the same time. A bit of muddy/sandy water came out.....

Thanks very much - I really don't know too much about this sort of thing.

 

[23vc]

Might be going to a soakaway then. Do you know if your house/street is meant to have separate storm drainage? What age is the house? Unless you’ve got any drain plans or any of your neighbours know the layout, you might want to get a local drain guy out to trace it/camera it

 

[GE90]

Thanks. not sure about the storm drainage. 1930's semi. Looked at the planning permission, but no drainage details online.

 

[Nige F]

That redundant pipe is an air inlet for the interceptor trap in your partially blocked main manhole . It is not used now . Get the interceptor cleaned with rods and a hose/pressure washer. Then you will see how that plastic pipe is arranged at the bottom Google interceptor / Buchan trap . Then when it's clean you can unscrew the access cover on the bend of plastic pipe and see what runs through that pipe ( I have a feeling it's the rainwater connection .) Don' t go spending £ on drainage guys yet .

 

[GE90]

That redundant pipe is an air inlet for the interceptor trap in your partially blocked main manhole . It is not used now . Get the interceptor cleaned with rods and a hose/pressure washer. Then you will see how that plastic pipe is arranged at the bottom Google interceptor / Buchan trap . Then when it's clean you can unscrew the access cover on the bend of plastic pipe and see what runs through that pipe ( I have a feeling it's the rainwater connection .) Don' t go spending £ on drainage guys yet .

Thanks very much. I have almost bottled it, as I called a small local family drainage chap, and he visited to give his thoughts. Well spotted, the sewer is blocked, so that needs jetting. He also suggested jetting both the gutter drain and garage pipes, as they might clear. CCTV has been recommended to see whats going on. Seemed a really decent chap, and although I am awaiting a quote, I think he said something like £270 plus VAT for either the jetting or CCTV, and the other £195 plus VAT. Discount if done together, and I'm South London. Local Facebook community group thinks this price is about right.......

I'll wait for the quote.....

Cheers

 

[ETAF]

Thats the sort of price i was quoted by a local firm, in west sussex, to look at an issue we had with a gutter downpipe into a soakaway.
BUT they also said as it went to an OLD 1932ish soak-away chances are it may all be silted up and a jet wash may not clear.

 

[Hugh Jaleak]

Can you lift any of the covers along the side of the house, and see whats under there? I have an inkling the drainage may have been relaid at some point, given the internal plastic backdrop into that open manhole, and the fact you have a plastic soil pipe and gulley, (the originals would have been cast iron and salt glazed stoneware, along with the drainage.) To save on excavation costs, the new drainage has been laid at a higher level, and simply dropped in to the last chamber to meet the existing invert depth. Is there another inlet to that chamber under the plastic can you see?

I would have also expected a property of that era to be on 'Combined Drainage', i.e. foul and rain water into the same sewer. Possible the system has been relaid and they've had the bright idea of diverting the rainwater into a soakaway which is now silted up....

 

[GE90]

Can you lift any of the covers along the side of the house, and see whats under there? I have an inkling the drainage may have been relaid at some point, given the internal plastic backdrop into that open manhole, and the fact you have a plastic soil pipe and gulley, (the originals would have been cast iron and salt glazed stoneware, along with the drainage.) To save on excavation costs, the new drainage has been laid at a higher level, and simply dropped in to the last chamber to meet the existing invert depth. Is there another inlet to that chamber under the plastic can you see?

I would have also expected a property of that era to be on 'Combined Drainage', i.e. foul and rain water into the same sewer. Possible the system has been relaid and they've had the bright idea of diverting the rainwater into a soakaway which is now silted up....

Thanks. I lifted one down the side, and it seemed like just a foul drain. House was extended to the side about 10-15 years ago. The last big chamber does not appear to have the garage and roof water draining into it. I’ve booked a jetting of garage and roof drains that are not draining away, a clean of the foul and cctv to work out what’s going on. Next Tuesday. Cheers.

 

[Hugh Jaleak]

Let us know how you get on please. My suspicion is, they've relaid the drains to just take the foul and diverted the rainwater into a soakaway, which has now ceased to function. Heaven only knows why....