I am going to plant a tree near a utility pole. It is several feet off the direct line from the pole to my house. The gas line was just marked (don't know why, but when my neighbor had it done they did mine also...) and it is near where I would expect the electric/cable to be. 3 years ago I had some landscaping professionally done in the same area and they didn't mark the electric, saying it was privately installed and they don't know where it is. The landscaper thought it was safe and planted 3 trees, but I am anal about these things.

1) How deep are these likely to have been buried in 2005?
2) Is it likely the electric and cable are in the same trench as the gas? (they all go the same place, and come from about the same place)
3) Are electric and cable sturdy enough to survive being hit by a shovel?

I know you haven't seen it, and things are often different than what they should be; just asking what is normal.