Hi everyone! We are getting ready to do the run , and I plan to put down 6 in. of road base gravel and top it with sand. My question is, do I just start with the base right on top of the grass or do I need to do a prep for the site? Also, do I do anything special to encourage drainage? The run will be covered, and the dimensions are 18x60. I just want to do everything possible to keep the run as dry as possible. I would love any advice- this is my first run! Thanks to all!