In the ’50s, my dad and I traveled from Enid, Okla., to Cabot, Ark., to drill 3,000 post holes 16 inches in diameter and 3 feet deep. After arriving at the Little Rock Air Force base and before signing the contract, we drilled a test hole in the most difficult location we were to encounter. The formation was to be original soil or fill dirt with no rocks or large boulders. This test hole turned out to be the easiest.
Most of the holes were easy, but some of the fill dirt holes had large boulders and the inspector said that if we encountered boulders we could just bypass that hole. The inspector noticed that we were bypassing many of the holes, so he felt we were bypassing many of the holes that only had small boulders. Note that we were being paid for all the holes whether we drilled them or not.