Loooong long waste pipe

[newhere]

Hi,
We want to put 2 toilets, sink and work shower in our warehouse. The run is about 18 metres from the stack (we can't use the local drains that we were led to believe we could use). We can't locate the bathroom any closer to the stack but do have permission to run the pipe along the length of the same 1st floor external wall.
The stack is vented. We're planning on adding a Durgo/AAV above the toilets or even a vent through the roof if possible.

1. Is this length of soil pipe feasible? Or what method can we use to make it feasible.
2. Do we need to add extra AAV's along it's length, if so how often? Can the y be boxed in with the pipe?
3. What size waste pipe should we use?

Thanks!

 

[htgeng]

What you're asking for shouldn't be rocket science to any decent contractor. I would run one 110mm waste for the two toilets and a 50mm waste for the shower/basin all the way back to the stack. If you try to cut corners and run a single pipe you may find unpleasant surprises if someone is in the shower and the toilets are flushed!

The fall on the toilet pipe doesn't have to be much above horizontal at all. If you can put an open vent above the toilets that would be advisable. Same goes for the shower as with that length of run it could easily suck out the water trap from the shower leading to smells.