Shower waste in a concrete floor

[RobOak]

Help. I'm changing a groundfloor toilet into a bathroom by adding a shower and a basin. The basin waste is ok, but how can i join a shower waste to the existing ground level toilet waste without raising the shower up by about a foot to get a decent fall (I don't want to use a macerator)! Is it ok to join the 40mm pipe to a boss underground?
I was hoping to 'Tee' the basin waste into the shower waste underground and run this pipe to the toilet soil pipe and connect into it (all below ground)!
Any thoughts!
I would welcome any help as I've just dug channels in the concrete floor and not sure how to proceed.

 

[Bahco]

Common practice is to raise the shower tray by approx 6 inches. You don't need a great fall for a shower, 20 mm will suffice per metre.

As for the underground stuff, well you should consult BCOs for advice.

Maybe the other guys will help you more on this one.

 

[kevplumb]

I was hoping to 'Tee' the basin waste into the shower waste underground and run this pipe to the toilet soil pipe and connect into it (all below ground)!

should be interesting if it ever blocks

 

[Nige F]

Is it possible to put in a gulley @ the right height for shower waste outside