Rain downpipe causing internal flooding

[mike42]

Hello All

For years now, whenever it rains we've had some flooding appear. Its taken me a long time to get around to looking at it because the internal area is really more like garage quality. Its a passage with a rough concrete floor and brick sides (unclad). There is a shared sewer about 6ft underneath it which I'm guessing the downpipe feeds. I found out so far that the downpipe drain is completely blocked and when the water backs up it seeps through a hole in the crappy wooden doorway structure. I'll look into sorting the hole but for now would like to unblock (or should I re-route?) the drain.

Its a clay swept bend presumably 4 inches. They would have been put in in 1970. There was a big problem with ivy in the past with roots going down the drain. I found it was filled to the top with soil. I've dug what I could out but need smaller hands and the wife wasn't going anywhere near it 8-(. A 1M single rod went in about 2/3 but then I couldn't ram it any further.

So one question I have is how likely/unlikely would a drain cleaning hose attachment to my power washer be to clear it? And if it doesn't, could I fit a soakaway nearby re-routing the water? Another question is would a clay trap typically have been fitted after the swept bend or would a trap be integral to the drain? That would make a drain cleaner even harder to remove the blockage? Thanks a lot for reading and for any tips.

 

[blup]

Persist with rodding then try a power washer, if not get a commercial company in to blast it, with a cctv survey first if there are root issues.

 

[mike42]

So got the drain attachment and it does absolutely blast jets of water out of it. In 2 minutes its cleared enough to not be totally blocked but still think don't think its full flow. A lot of silt and yet the soil here is clay.

Pretty sure its a trap as water always stands at the bottom but when I pour say 5L in from a watering can it goes through if I don't pour too fast.

One of the nozzles has 3 jets at the back and 1 at front. The other is similar but spins. I don't know but total guess is there are still some thick roots down there. Maybe they'll rot away over time so maybe will jet every year. For 20 odd quid its a fantastic bit of kit.

I've had the drain washing hose snake around the trap (was nearly stuck at one point and had to really yank it hard) for a total of maybe 5 minutes active flushing.

Is it worth doing more I wonder ?

 

[Hugh Jaleak]

That should be a Gully there, as it has a Waste pipe going into it, and I suspect will be connected to a Combined sewer, so would need to be Trapped to prevent odour issues. Grey Water shouldn't really go to a soakaway, so I'd be looking to get the drain unblocked, and see what your options are going forward to prevent reoccurrence.

Roots in a drain do not rot, they just multiply! Nearby vegetation, Leylandi can be some of the worse culprits, will put out roots to find water, if they can find their way into drain or sewer they've got it made, and so just grow bigger/more roots, continuing to fill the pipe, outwards and along.

It is possible to remove some root ingress with a Jetter, Spinner jet would be the best option to start with and try and break through, root cutters and Chain Flails are also an option, but need a perfectly round pipe or you risk them getting stuck. Other machinery is available, e.g. rotating cutters which will also remove roots, but as with the bigger Jet Heads, they need a full pipe diameter to access, e.g. going from a manhole.

I think your options now are the following. Either, persevere as you are with your own machine, break as much as you can out and see if you can restore flow, but bear in mind it'll be an ongoing battle.

Or, get a Drain Specialist in, (better looking for a Private Company and get a fixed price before they start, (and avoid anyone with a brightly coloured van, or has any A's or 1's anywhere on their Name, Paperwork or Website.) Need Drain cleaning out and ideally a CCTV survey to ascertain it's condition before/after cleaning. If root ingress is a major issue, get roots removed and drain lined to prevent recurrence. Gully will probably have to be broken out to do this work, but provided drain isn't buried in concrete, replacing it with plastic isn't difficult.

Lastly, full replacement, (if CCTV shows roots/collapse is an issue), but this would be a last resort and only if the pipe couldn't be cleaned and a liner fitted.

 

[mike42]

Thanks a lot Hugh - it was worth waiting for a high quality answer.

Since my last post, I spent part of yesterday alternatively jetting and then sucking up the waste with an old but quite powerful wetndry vac. Well, I fairly quickly got to the point that water would drain at a moderate speed. When I went to suck up the debris it was just pulling in huge amounts of silt and pea-shingle. At the time I thought the pea shingle had dropped in over many years as the border to the house is covered in the stuff (you can see some of it in one of the pics to the left).

But then when the water flow wasn't getting any better, I thought maybe the drain has collapsed and I'm simply scooping up all the 50 year old building materials around the break. Do you know if they used pea shingle back then to bed their drain pipes in?

The jet didn't get beyond about 2M in. And every time I ran the jet, it would give me another load of silt and tiny stones to hoover up. In total I'm probably close to a full bucket now.

 

[Hugh Jaleak]

Peagravel (as I've always known it), came into use I think around the 70's, so quite possibly would be my answer. Need to also bear in mind, if roots have got into the drain, and have found water, then they'll be growing quite rapidly, a small crack in the pipe could have been widened drastically, and with introducing high pressure water, you've possibly washed out a big void, with soil, stones and pieces of pipe heading downstream, as well as what you've brought back.

My honest opinion now is, time for CCTV and see what is actually going on down there. Plan remedials from that.