If you're travelling from Rhyl to Manchester are you not on the M56? If so you could be talking about Stanlow Oil Refinery (Shell) at Ellesmere Port or ICI at Runcorn. Presuming you mean industrial plant and not vegetation!
Do you mean where you pass through all the cones, and they are building a new bridge and roads over a massive area. It is one big building site?
We have been passing through this all summer on the way to our caravan in North Wales.
Sorry I dont know the answer, but I hope someone does, because I would like to know as well.