What should I do about deck footings near the house?
Contact the building inspector for your area. They will know whether the whole area around your house was dug and backfilled, or whether the ground is undisturbed. They will also know what is under the dirt and how far down you need to go. I live in a very rural area and my building inspector remembers a TON of details about my house to the extent of not needing to come out for a site inspection pre-build because he remembers from a previous visit. But even in the city there is documentation that the inspector can look up. They want you to be safe so they will help you do what you need to do.