If I recall correctly the ground rod(s) if more than one must be at least
10' apart and the number required will be a function of the grounding
efficiency of the soil. In addition the wire must be a continuous loop
without splices at each rod.

Ground rods are normally bonded by interconnecting them with #6 copper
wire. This may be one case
where using larger wire is not desireable -- use the #6 between the
electrical system ground and the
lightning type grounds, but perhaps use larger wires between any other
electrodes in the respective