If you want to be super technical, 18 to 24 inches away from the pool wall and 4-6 inches below sub-grade, but your description is probably close enough if you don't get a picky inspector.The bond wire around the pool is supposed to be roughly 15" away from the pool all the way around it and buried 4"-6" below the finished grade.
NEC 680.26 (B) (2)(b) (4-5)
Unless you were going to do concrete and rebar, then you would just tie into the rebar.