This is how I set my fence posts. I dig down atleast 4' (which is the frost line). After putting the post in place, using a string line I backfill the hole with exactly what came out. Compact it as you go, and use water to help compact. Keep the post plumb as you fill. My dad and I have been doing posts this way for 20 years without any issues. #fencebuilding #fenceinstallation #fenceposts #diyfence #fencebuilder #privacyfence #carpentrytools #carpentrywork #clamdiggers #postholes #deckbuilding