Hi Pking and welcome to GoY. What are you going to do with the ground after you've covered it with the membrane?

If you want to reseed you need to remove the old turf first.
And membrane is not a good foundation for a lawn, if that's what you're thinking of doing.

Laying down membrane in my garden for weed supression was a big mistake. Eventually weeds will grow on top of it and if the membrane was of the porous type as mine was, the weed roots will grow right through the membrane making them almost impossible to pull out. To deweed, I had to pull out the whole membrane and it was back breaking work.