Are there tolerance standards for the use of shotcrete in pool construction? For example, in regard to the pool depth, what is the accepted variation from the depth specified?

We are not aware of specific tolerances for shotcrete in swimming pools. Shotcrete is a method of placing concrete and the cover over reinforcing steel should be the same as that for cast concrete. With respect to the depth of the pool, this would be a building code issue, not a shotcrete issue.