I just had one of my new construction guys call and said he was turned down for a fire pump install, he did not install or connect to a grounding electrode for the fire pump service. (he should have known better anyway, he has a masters license, and of course the engineer that drawed the blueprints didn't know any better either, because he left it off) When he asked the inspector if the exsisting cold water and building steel (commercial building)was Ok, the inspector said he wanted a ground rod too. I told him to politely ask the inspector where in the code he was required to also drive a ground rod when the other two grounding electrodes were present.
In the 2008 code, I believe the code reference might be 250.52(A)(2) and 250.53(D)(2)
250.52(A)(2) tells us that the building steel only counts as a grounding electrode if it is connected to ground by one of the four methods. Note that a metal water line is not one of the four methods. It may be that the building steel did not qualify as a grounding electrode.
250.53(D)(2) requires a supplemental electrode for the water line.
If the building steel does not qualify as discussed above, then the inspector may have considered the rod to be the supplemental electrode, or he may have wanted it to satisfy 250.52(A)(2)(3) so that the building steel could qualify as a grounding electrode. But in either case, he should have been asking for 250.56 compliance as well.
The inspector stuttered when he said it, so I figured he was not sure and defaulted back to one of those "that's the way it's always been done around here."
I might stutter a bit when asked the same question because the thought would be running through my mind "Does that building steel actually qualify as a grounding electrode in this case?"