Inspection chamber problem

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26 Apr 2020
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United Kingdom
Hi looking for some advice please. Bought house and recently discovered inspection chamber just outside building where main waste runs into sewer via inspection chamber.
Problem is the run between waste pipe and sewer is concrete and not enough elevation drop so waste routinely stuck here. Any advice on how to improve?

Have attached pic for info.


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So, you have a waste pipe, and a soil pipe discharging onto concrete benching?
Two inlets and one outlet?
Or is there a third inlet in the top LH corner?

Are you complaining that the concrete benching is too flat - not enough fall?

Has your manhole been altered that you know of? It appears to have a peculiar construction.
There seems to be a lot of loose sandy gravel in the benching channel.
Thanks for replying. Apologies, this is a first time post and probably lacking detail.

“Peculiar construction” sums up entire house. A 1979 built unique exposed breezeblock oddity so not surprised to hear inspection chamber also strange looking!

2 inlets, one waste and one soil (soil is the drainage from monoblock drive positioned higher up as house built on a hill).

Waste reaches end of grey pipe from house and usually sticks on concrete straight away. Eventually pressure builds and it may tumble down a few inches but bottom line is that the concrete run from there to the sewer pipe is too flat and possibly too rough for waste to flow away (sewer entry at bottom of pic so 90 degree angle from waste pipe).

Hoping to find some sort of solution that means I don’t have a calendar reminder each week to fetch a big stick and nudge away that weeks family “output”.
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First one, could do with clearing out the bottom of that channel- looks like a load of rubbish in there at the mo

Second- yeah that's not an ideal design. Its hard to tell but is that brown inlet higher than the grey one? If the bottom of the brown is above the top of the grey you could put a 135 bend on the end of the grey & extend the brown so it drops past the grey with bend on

Or another worthwhile experimental bodge- get a lump of flat plastic (felt support trays are my favourite), cut it to length so it will wedge into the sides of the chamber with the bottom edge in the channel (from brown inlet to outlet). Try it for a week- if it runs clear then that'll prove your theory (about the benching being too rough).

How deep is that manhole- it looks like about 500mm? Wouldn't be a massive job to dig it out & put a round plastic chamber at the bottom
Thanks for your reply. Typically:
Soil in the pipework world refers to a soil pipe carrying sewage from WC's.
Waste refers to sink and bath water.
Perhaps both soil & waste are combined in your grey pipe?

Your m/h might have been carelessly altered at some time.
It would be a straight forward job to crack out, and relay your benching to falls - thing is, is the outlet pipe at a correct falls to wherever its going? Make sure its not blocking as well?
There should be falls from the benching to the next m/h or the main sewer line.

Having said that, it might be possible to crack out the benching, & then construct new benching to a correct design with a perfectly smooth surface.
Raising the new benching surface at the back would help the flow and be self-cleansing.
You are absolutely correct (and my lack of knowledge brutally exposed! Ha ha!) Soil & waste from house leaves via the grey pipe. Brown pipe purely driveway water. Brown pipe does sit higher than grey pipe so it sounds like there might be a few options to explore.
Thank you very much for feedback, lots of food for thought. I think I’ve had so much to do on the inside that by time I’ve come to this problem on the outside I’m mentally shot and out of ideas.
Enjoy what’s left of Sunday, cheers
routinely tipping a bucket of water down the driveway drain should keep things moving as it runs the right way to keep things flowing.
apart from the obvious that the grey pipe should not be down there in the first place.

That manhole is not sealed, and all that crap will be going out into the ground, and if that's near the house its a candidate for foundatiuon subsidence due to soaking the ground.

And one of the problems (the problem ?) is that its not properly formed to allow the water to flow smoothly, so no wonder it gets blocked.

And having the waste and rain water in the same manhole is a bodge, and unlawful - don't let the water company find out. Or if the drive has been resurfaced within the past few years, the planners!

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