Grounding of Propane Tanks

I have a propane tank.  It has the copper piping running only a few inches underground and then connects to the piping in the house.  I've been securing the legs of the tank to get ready for a possible flood along the Missouri river.  I used thick wired to wrap around three of the legs so far.  The wire goes only a couple of feet into the ground and is encased in cement.  I can sense a difference in the way it feels inside the house.  I'm thinking I'm getting a little bit of grounding on the tank and that is what is making the difference.  I'm thinking I should do a real grounding job on the remaining leg.  Like put a grounding rod in the ground and then use thick cable to connnect to the grounding rod that is tied around the leg of the propane tank.  Anybody have any thoughts on that?