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Design of drainage in to be built over mains manhole


Jml

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Our extension will be built over a mains manhole, which will have to be moved or covered over anyway.   We do have another manhole on our property serving the mains drain. I have been trying to work out how this will work so that I can put in a build over claim to Thames Water, without success.

 

At the moment the manhole to be moved/covered has FOUR  pipes coming from our property going ito it, all from one side of the manhole:

 

1. Roof rainwater, which when new flat roof built/ extended will need to go to a new soakaway in the garden. (And then there were 3)

 

2. Soil vent pipe.  This runs vertically to the roof outside the current house then has a long horizontal run in the loft space does a zig zag and then pops  out next to our dormer window. No other pipes are attached to it.  It needs to be moved (I THINK) as it sits right at the corner where the new extension will start and therefore, as far as i can work out, is in the way of the new block and beam floor.

 

3. waste water from sink, bath, and old kitchen(to be new utility room)

 

4. Waste from loo in bathroom.

 

In addition we need a new connection from the other side of the mains for the waste water from the new kitchen.

 

See Picture.

 

The mains drain is such that connections to it will have to be via a preformed junction(s).

 

i was thinking of creating one connection only to the soon to be covered manhole, get rid of the soil vent pipe, create a soil stack where the loo is, to which the loo, waste water from sink, bath and utility and from new kitchen run to, then this attaches to the remaining pipework of the soil vent pipe to the roof.  Not ideal a loo soil is in floor of bathroom so would loose space from stack and connecting new kitchen waste to it through existing house wall is a problem(?). Also whilst can rod down flow of sewer from other manhole, what about the metre or so between bottom of soil stack and the new connection to the sewer?

 

See picture.

 

 

CB7FF2B1-65B8-49CD-BD73-84D57DADD013.jpeg

1566FEF3-D0A8-408D-8DC1-7F9BA633B802.jpeg

 

Any help much appreciated, as fed up waking up thinking of possible drain designs, and worrying Thames Water will not like any of them!

Edited by Jml
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I’d put a pair of 45 or Y branches into the existing manhole, one each side. New stack into one - that needs to be your venting compromise unless Thames agree someone else is venting the sewer as you could fit an AAV. Second branch to the kitchen, carry on up past it into a rodding eye if you can and roberts your aunties husband ....

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19 minutes ago, PeterW said:

I’d put a pair of 45 or Y branches into the existing manhole, one each side. New stack into one - that needs to be your venting compromise unless Thames agree someone else is venting the sewer as you could fit an AAV. Second branch to the kitchen, carry on up past it into a rodding eye if you can and roberts your aunties husband ....

 

Many thanks for your response.

 

Could do vent into other manhole, may be easier.

 

Second branch to kitchen could easily continue to do rodding eye.  Problem i forsee is that kitchen waste further to right than manhole, so waste has to run to left (as on diagram) then curl round to meet current manhole position.

 

How do I rod bit between current manhole postion and new stack?

 

Would love ‘robert to be my aunties husband .......’

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15 hours ago, PeterW said:

I’d put a pair of 45 or Y branches into the existing manhole, one each side. New stack into one - that needs to be your venting compromise unless Thames agree someone else is venting the sewer as you could fit an AAV. Second branch to the kitchen, carry on up past it into a rodding eye if you can and roberts your aunties husband ....

 

I’m sure i’m making this more complicated than it should be.  Having looked at various documents and leaflets on the web it seems I cant connect to the sewer with an angle of less than 90 degrees from the direction of flow.  This means as the proposed kitchen waste is further down steam than the manhole I need another solution, without creating yet another join to the mains further down it.

 

Drains seem to run in straight lines, so a gradual backwards curve, is probably not the answer. (?)  I know i could move the kitchen but it fits neatly where it is.  What I therefore thought was two drains with rodding eyes, see pictures.  Thoughts??

 

FEEAD674-B659-4D46-A003-95FD92C2318C.jpeg

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21 minutes ago, le-cerveau said:

Have you got an overall ground floor layout including drains the people can work on?

 

Have proposed downstairs, but not with drains.  Will work on that tonight.  

D7CCFA6D-F533-4881-ABF5-697D5CDE34AD.png

9157685D-EC44-4415-8399-4393C64575C6.png

Edited by Jml
Show existing ground floor
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10 minutes ago, Jml said:

Just found diagarm for changing y connection at sewer into 90 degree bend on different thread ( dont know how to quote that thread on this thread), but thanks to @Nickfromwales. Easy when you know how!

Top right hand corner of each post 'box' has a feint square. Next to that, to the left, is a ( hyperlink ) symbol thingamijig which you press once and a box pops up with the link details. Select, then select all, then copy. Tap the text box to get rid of the details and then go to the destination thread. Press paste and give it a couple of seconds and it'll pop in as a quote style link in all its glory. ;) 

 

Like that. ?

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15 minutes ago, Nickfromwales said:

Top right hand corner of each post 'box' has a feint square. Next to that, to the left, is a ( hyperlink ) symbol thingamijig which you press once and a box pops up with the link details. Select, then select all, then copy. Tap the text box to get rid of the details and then go to the destination thread. Press paste and give it a couple of seconds and it'll pop in as a quote style link in all its glory. ;) 

 

Like that. ?

 

Ok, im being seriously thick here,  found the hyperlink thingy and box popped up with link details, but cant then copy those or paste over! I am using an ipad which can causes problem on various sites or i am just doing it wrong?

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I'm on iPad right now and did the above

When the box pops up it should have the text already in the box. Like this. 

 

 

image.thumb.png.27d18f0a69b8ac161ed459e5517a5396.png

 

Then just tap on that text to get a cursor and then tap again to get the slelct - select all tab. Choose select all. 

 

image.thumb.png.13b4f1cd35c1a9d86d7c8c0a6df86ae3.png

 

Then select all, then copy and your done. Just try again. If you duplicate post I'll just delete it for you ;) 

 

 

Edited by Nickfromwales
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