I'm thinking of building some raised garden beds, about 12 inches deep.
Does anyone know if that is deep enough to discourage the bermuda
grass and other weeds from creeping in?

I plan on putting down a few layers of brown paper bags and newspaper
so hopefully that will help too. Any other suggestions on keeping the
invasive grass out of my raised beds? (Or is it a lost cause and I
just need to get used to pulling the bermuda runners?)