What is being used for the equipotential plane mentioned in 682.3?

George:
The two (2) that I had (Retention basins, with aerator pumps & services); one used the rebar (12" +/- squares) within the slab, #8 solid Cu (including fence & jumper on gate). #2 used the 12" Cu mat under 3/4" blue gravel, #8 solid Cu (including guard rails)

Both were under '05 NEC at the time.