About 15 years ago I found a post of how to build a sloped driveway from an English web site. The process was simple so I did it. Wet ground until it slightly pools, lay down a good layer of gravel until you cannot see any earth, layer local clay on top, layer gravel. pound the ground energetically with a tamper or roller. Layer with local clay, layer gravel tamp down wet surface. Add more gravel as the clay shows through. Repeat. I did this 5 or six layers 15 years ago and it's held up beautifully on a heavily sloped and used driveway. Every year big tree trucks drive on it a couple of times. If a chunk gets dug out 'cause someone spun a tire. It's easy to patch. Maybe in 5 or 6 years I'll put another layer of two on, maybe not.
