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Underground drainage advice please.

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Discuss Underground drainage advice please. in the Ground Sourced Heat Pumps area at Plumbers Forums

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mutley racers

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Hi all. I have not done any drainage as of yet but will be next week.

I am taking out a macerator and instead installing a soil stack and underground drainage to an existing man hole.

Q1) can I use a short radius (rest) bend at the foot of a stack? When looking online it does say that this is what they are for. But there are also long radius bends which you can use.

Q2) How far below ground does the drainage pipe have to be?

Q3) Can I use sand to lay the pipe on and then cover it with sand or should it be pea shingle? Maybe pea shingle will go a lot further.

Q4) I am hoping to pop through the side of the manhole close to 2/3s the way up and drop down and chase shoe into the benching. Does anyone know what mix this benching is? I know there is a name for this installation but I cannot think of it.

Cheers all
 
Are you looking to get it done to pass building control or are you looking for trouble free future? (ie is it your own place).
If the former, do whatever they let you get away with.
If the latter, dig down and do it properly. The “least work” robust way is to dig right down at manhole so as to enter horizontally at sewer pipe level. A couple of feet away from this you can then employ the ‘back drop’ method with no worries - better if you use a nice slow bend at the base of back drop and you also need to add rodding access to this (basically at top of back drop use a branch rather than bend, with rod point on vertical section).
I did this at home 7 years ago and no problem since (why did I write that down.....)
 
Ben-gee said:
Are you looking to get it done to pass building control or are you looking for trouble free future? (ie is it your own place).
If the former, do whatever they let you get away with.
If the latter, dig down and do it properly. The “least work” robust way is to dig right down at manhole so as to enter horizontally at sewer pipe level. A couple of feet away from this you can then employ the ‘back drop’ method with no worries - better if you use a nice slow bend at the base of back drop and you also need to add rodding access to this (basically at top of back drop use a branch rather than bend, with rod point on vertical section).
I did this at home 7 years ago and no problem since (why did I write that down...)
Click to expand...


Hi, thanks for the reply. It is at a client's so belt and braces and with regs
 
Called them and they say I can do internal backdrop as long as there is still room for access. Not sure what space it is you need but it is a standard manhole drain so I would have thought big enuf
 
How much space you need depends on the depth of the manhole. Over a certain depth you have to have enough space for a "man" to get down the hole so in theory an internal backdrop might encroach on that.
How deep is the manhole ?
A normal rest bend isn't a short radius bend, two different things. Use a rest bend as they are easier to rod.
 
Thanks for the advice so far guys.

So reading up on drainage, it is most likely I can do an internal backdrop as the man hole is about 600 x 900 and about 1.6 metres deep.

Upon reading, it says I need a flexible connection 150mm away from where the pipe enters the manhole. Does anyone know where I can find one of these?

Also, what are the fittings called that you cut into the benching? Or can I just cut a spigot elbow in half to create this open channel?

Cheers
 
Another question guys. I will be running a new toilet soil pipe out of a pitched roof to the stack. Do I use a pitched roof slate but reverse it so the pitch is pointing down and then I shall get the slope to the toilet? Or do I use a flat roof one
 
mutley racers said:
Another question guys. I will be running a new toilet soil pipe out of a pitched roof to the stack. Do I use a pitched roof slate but reverse it so the pitch is pointing down and then I shall get the slope to the toilet? Or do I use a flat roof one
Click to expand...

How high is this toilet? Any photo or diagram of proposal?
 
Ok, managed to dig them out.

20190527_205616.jpg


20190527_205639.jpg


20190527_205712.jpg
 
CBW1982 said:
Ok I a make a it’s more sense from that. So you propose a soil pipe somewhere? Might be easier to run pipes out of eaves?
Click to expand...

Do you mean out through the soffit board then? Still need to install the vent through the roof though. Unless a house in that row has a vent on it so I could get away with a durgo.

Would it be OK to run the bath and basin waste into the toilet branch or will the BCO want to see it going into the main stack?

I want to run the soil pipe next to the down pipe.
 
mutley racers said:
Do you mean out through the soffit board then? Still need to install the vent through the roof though. Unless a house in that row has a vent on it so I could get away with a durgo.

Would it be OK to run the bath and basin waste into the toilet branch or will the BCO want to see it going into the main stack?

I want to run the soil pipe next to the down pipe.
Click to expand...

Yes through soffit, providing it’s not asbestos. Why would your bent need to go through roof? Could take it 1m higher than gutters on an offset? Do you mean bath and basin in the same stack as wc? If so, i don’t see an issue.
 
CBW1982 said:
Yes through soffit, providing it’s not asbestos. Why would your bent need to go through roof? Could take it 1m higher than gutters on an offset? Do you mean bath and basin in the same stack as wc? If so, i don’t see an issue.
Click to expand...

Hi, I do mean into the same branch as WC? Which then goes into the stack through the soft rather than 3 pipes coming out of the soffit and into the stack.

Also, any ideas on what the flexible connection should be before the pipe enters the manhole?

Thanks for all the help by the way.
 
I would go with the length of soil connecting to wc pan, then a bossed connector to take bath and basin all on same horizontal yes, then only one pipe outside. Not sure what flexible connection you’re on about? However if it’s what I think it is then a soil bend, piece of pipe and another soil bend at the bottom.

Short bossed connection Short Boss Pipe 110mm Black

You’re welcome for the help, it’s what we’re here for.
 
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