You mention 10 inches deep. I usually will not have more than an additional 5"6" laying down at an angle in the trench/hole and the root ball is usually not more than 5 or 6 inches from the surface.
Yes, the “noted previously” part was mostly about our rain and soils problem this year. I’ve had to work on our vehicles all day, today, but I suspect if I go out to the garden (esp. “plot 2”) and dig, I’ll hit water no more than a few inches down. Granted that the last rain finally quit about 36 hours ago...