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Posted: Mon Feb 10, 2014 10:58 am
by screig
I have three steel rectangular manhole covers in my back garden. When I open them up, I was expecting to see a channel. However there is a pipe with a bolt down inspection plate. What is that all about?
How would I run a new drainage pipe in to this?
Posted: Mon Feb 10, 2014 11:37 am
by msh paving
A picture would help showing inside all 3 lids, could be anything without seeing it, MSH 
Posted: Mon Feb 10, 2014 11:54 am
by screig
I will take a couple of pictures, when I get home. However in the meantime it looks very much like this
Would this be under pressure or something?
Posted: Mon Feb 10, 2014 9:34 pm
by screig
Posted: Mon Feb 10, 2014 9:50 pm
by lutonlagerlout
mammy I'm blind :O
LLL
Posted: Tue Feb 11, 2014 9:41 am
by Tony McC
It *might* be a rising main, carrying water and/or sewage under pressure. That would be the most common reason for using a sealed access plate, but it's not unknown for eejit builders, with little experience of drainage and a handful of fittings they somehow acquired, to jury rig a drainage system using all sorts of bits and bats.
If I was on site, I'd be looking for how these 3 chambers are related spatially, and what it is they might be serving. So, I'd determine invert levels to ascertain which is up and which is down, and then look for any other drainage installations, whether it's chambers on neighbouring plots, outfalls to a ditch, manhole covers in the road.....anything that would allow me to build up a picture of how the drainage system lies.
On the limited information we have to date, my best bet would be on it being a rising main, so somewhere, maybe not on your property, but somewhere locally, there *must* be a wet well, the sump point where all the effluent is collected before being pumped up to another sewer.
Posted: Tue Feb 11, 2014 9:57 am
by screig
Thanks for that.
I have three covers at the back of the house and one at the front. At the back
* One is close to the back of the house where the two vertical soil pipes (these are boxed in, inside the house, 1983 build) are.
* One is inline with a downstairs toilet, give or take.
* Last one is near the kitchen.
At the front the only thing that is nearby to the manhole cover is a drainpipe (from the roof gutter) that is cemented directly in the ground. I mean there is no trap. The pipe runs down the side of the house and goes straight in the ground with some cement at the join. Thats about a meter away from the manhole at the front.
I was planning to put a patio over one of these and run some new drainage in to it.
Posted: Tue Feb 11, 2014 10:19 pm
by ringi
They *might* be one-way (non-return) valve to stop sewage flowing into your house if the sewage backs up for any reason.
Posted: Wed Feb 12, 2014 9:57 am
by Tony McC
On those photies, I can't see any maker's marks which would help identify the fitting, and it's not one that I immediately recognise.
Can you get any closer to see if there is a manufacturer name, part number, or any other text on that cover plate?
