I am doing a small wall install ( 100' long, 3' tall, 6 lannon steps) and the customer wants to put a fence at the top of the wall. My concern is trying to put the posts into the drainage stone. I konw that it would not be easy to dig the post in (stone caving in). My first thought is to put in PVC sleeves for the posts and capping the sleeves off. I would make the sleeves about 5' long (so they would be anchored into virgin soil). Does anyone see any problems with this idea? Any improvements? Thanks in advance.