Drainage Proposal advice Sought

[hamazz]

as part of our side extension we decided to put in a new manhole, existing all surface water and soil are combined and go into a manhole in the neighbours garage.
we want to try and make away with any internal manholes within the property, so will need a 16m run from the front to the rear of the property, on the attached drawings is a quick sketch of what we are thinking of doing. we already have permission from thames water to connect into the existing public sewer, the manhole will be sited about 800mm away from this pipe as it cannot be built ontop of it.

is it ok to have multiple branch connections in the middle of the run?
i have put in orange an alternative run to the red one, would this be accepted at all???

the pvc pipe will have to run through the foundation at the front and rear of the property, so im guessing bco will want it deeper than the pipe there

any advice greatly appreciated.

hamazz View media item 52887

 

[hamazz]

also just wanted to double check, pipes need to be bedded in 100mm shingles, and covered by at least another 100mm ontop before throwing soil over it again?

hamazz

 

[Agile]

I would certainly do it differently!

The sink at the back I would take directly to the front!

The toilet and basin I would try to combine at that point and take it straight towards the extension so it is not under any walls and then through a slow bend towards the front.

I dont know if my suggestions are permissible as building regs have a lot of custom and practice aspects!

But if allowable they do seem to be simpler!

Tony

 

[hamazz]

tony

thank you for your comment, im not sure i clearly understand the bit about taking the toilet and the basin straight towards the extension??
i ran the kitchen sink to the rear rather than the front, so would help with keeping the run clear, with the water running from the sink and w/c d/w etc.

i was thinking of taking the 2 en-suites next to each other on a separate run to the front, but also have a surface water run next to this, so didnt really want 3 or 4 pipes running next to each other towards the front of the property




hamazz

 

[Hugh Jaleak]

I think it highly unlikely BCO will allow your proposals, golden rule of drainage is all pipework must be accessible for rodding in event of blockages.... Bends and/or junctions under the floor are very unlikely to be permitted.....

Either, take the 2 en-suites on the right hand side out through the adjacent wall, fit a gulley for the kitchen sink waste, and put a chamber externally running to the front, the en-suite on the left can be brought out to the front, either connect two runs at front before connecting to existing sewer, or make seperate connections.

If that is not possible then I cannot see how a chamber inside the property can be avoided. The 3 en-suites could be commoned into the one chamber, with a connection run in 110mm to the kitchen sink position. This could then run out to the front as per your drawing. BCO will have final say, but be prepared to have to fit a chamber internally.

 

[hamazz]

thanks for the comments,

the adjacent wall is a neighbours property so no option of putting anything there, the idea of having a manhole at the front and rear, was to be able to rod the whole line in one go.

the toilets will all be boxed out in the bathrooms, so could maybe add a rodding position behind it somewhere,
or i could run the 2 bathrooms on the right with their own run straight to the manhole in the front.

the issue is this is ground floor plan, the first floor has bathrooms above in the same locations.

hamazz

 

[Hugh Jaleak]

It's not rodding the main run that presents the problem, it's accessing the branches! Rods cannot be steered once in the drains... Rodding eyes are a possibility, but opening one when the pipework is full of effluent is not a job for the faint hearted and certainly wont do your decor any favours either.....

Best option is to discuss with Building Control what is acceptable, they will need to sign the work off so better to get it right first time!