Adding outside drain advice needed Drainage and wastage systems and plumbing help, advice and answers

[DCal]

Hello all
I need help understandig how to complete this project correctly.
In the picture you can notice some lines . the white is the actual kitchen sink/wasing machine drain . My question is, what is the correct way to add an extra drain on the extrnal wall (red Line).
any help is very much appriciated .

[DCal]

so these are few more picture i think will help.
the white pipe already in place is the condensate pipe of the boiler and goes in the gravel as you can see.
in the meantime I have been told to drill a hole on the side of the chamber, for a 40mm waste pipe.
because the only thing that will pass in the pipe is soapy water at most, the fall i have to give is not that much.
then fit an elbow & a downpipe to almost reach the bottom of the MAC, that is to avoid any splashing noise.