Plumbing in the Home/Service line depth
Reputable long time local plumbing contractor installed 100' of 3/4" pvc from water meter to water service inside our home. Trench was dug 8" to 10" deep. Frost line in our location in north Georgia is 5" to 7". Asked the licensed plumber doing the work if this was deep enough to insure that pipe would not freeze in extreme temperature and he assured me that this was standard for doing this in our area and said he had never seen freezing at this depth. The work he did appeared to be first class in all respects both outside and inside the house. They had previously done a large job replacing galvanized with cpvc and that has been trouble free. Not looking for trouble, just wanted an unbiased opinion if depth ok.
Based on your information and what I know about the frost patterns in Georgia I would say you are going to be just fine. The 5-7" depth has been exceeded and in order for a freeze up at 8-10" the temps would have to be extreme for several days in a row to freeze the water line. Just as an example, here in upstate NY we have a frost line of 48
" We put in meter pits that are nothing more than 18 - 20" pieces of plastic pipe stood on end. We then bring the water line up from the 48" minimum depth, install a meter and then elbow it back down to 48" again and continue it into the house. Thereby making a loop so-to-speak. We get below zero temps quite often and the lines still don't freeze. It sounds like you have a good company working for you that you can trust. Often rare in this business.