I have been using nr 3 rebar stuffed inside 1/2 copper tubing instead of
copper clad ground rods for years. You can beat the hell out of them when you
pound them in and the rebar doesn't allow much crush. I sharpen the ends of
with a grinder blade for my circular saw for easier burial. The cost for a
ten foot section of tubing and bar...around $5.
If you want to jet the tubing into the ground you can omit the rebar and the
cost will run around $3.50. In any case it is pure copper going into the
hole..no chance of it corroding off...and it's CHEAP!