Safe answer: dig a 2.5' deep post hole, and cover it. If it doesn't show water at the bottom, you should be good to go.

Re Chattanooga: my younger son, who used to think of Chattanooga as a bit of a dead-end, has now concluded that it's his preferred location. Florida and other places are nice to visit, but not for living. Flat doesn't make him happy, and a LOT of the land west of the Miss. is pretty flat. And he's decided that big cities are best visited online!

Ironically, there've been a few articles lately about how Chattanooga is becoming 'hip'. It's been an outdoor mecca, for awhile (local world-class hang-gliding, mountain biking & bouldering; near-by world class white water + lots of TVA water, Forest Service semi-wilderness, etc). But the redevelopment on the north side of the TN + the gigabit Internet (Chattanooga has the fastest available internet in the US) has brought folks here for 'cool'.

Who'd a thunk that redneck Chattanooga would be a hipster heaven?