Redoing a big portion of my drive way as it was getting higher than the entrance into my shop and I did not want it flooding again this year when the snow melts, I cut/dug the top layer of gravel/dirt off so I am now down to topsoil/clay base which I dropped and sloped to where I want it. Before I put the gravel back on what should I but down as a base??1 inch- 2 inch -3 inch pit run or anything?