My drive is currently very scruffy-looking tarmac - lots of potholes and it looks like somebody has spilled a load of concrete on it at some point.
I want to lay a gravel drive and have heard that putting gravel directly onto tarmac (after filling the potholes obviously) isn't a great idea. So my question is, how much of the old drive should I remove? E.g. is it ok to just dig down a few inches, then lay some scalpings and put the gravel on that? Or should I excavate to the full 200mm suggested in the "Driveway and Path Project"?