Grounding Near a Gas Line

[JPRYOR@UGA.CC.UGA.EDU (Jay Pryor)]

I'm putting a rooftop tower up the summer and will ground it somewhere
behind my house. Problem is, in the area where I would like to put the
ground rod, there is a gas line running underground from the house
(specifically from the hot water heater) to the backyard grill. So,
how far away from the gas line can I safely put the ground rod?

Seems like nothing's easy!

Thanks.
Jay/K4OGG