Large garden project

This garden project has me tree surgeons guys laying paths a big garden the amount of couch grass.

Apart for pulling and digging it out ,dont want to use chemicals .

What can I do .

 

Sorry, but I would use roundup - just the once to get it under control.

Barrier membrane perhaps?

Digging it out will work (done that, back before we had Glyphosphate, not keen to do it again!!), but you need to be thorough and then vigilant until its all gone. If the area is small that woudln't be too bad, but you say "Large garden project ..."