Hi, I already have a Cotswold stone gravel driveway. It has a few small pot holes which I can fill and wack down. It has been a good 7 - 8 years since it was topped up and as it has access to my next door neighbors house, it is looking a bit tired. Can I just lay the new stone chipping on the top or do I need to wack down what is already there? The problem at the moment is that the stone has almost completely gone and what is left is a slurry. If I lay straight on top of this it will move around. What is the best prep method before laying the new layer of stone chippings?