In article , Dave Lemper
wrote:

The soil in central Texas is called Caliche with a lot of clay,
CaCO3 & shale. Attempting to drive in a ground rod
yielded only a mushroom on top & blisters on me.
Local tool rental place has concrete bits, but maximum
length of 18 inches. Possibly longer bits are available in
a larger city.

Dave-

Last year there was a discussion here about sinking a ground rod using
an "SDS Plus" Hammer Drill set to hammer-only. I think it was Ian
White, GM3SEK, who proposed that method. There is also an article at
http://www.n4lcd.com/groundrod/ that proposes a slightly different
method of coupling the hammer drill to the ground rod.

The question is whether Caliche can be penetrated by such a method. Has
anyone tried it?

Another consideration is whether or not there is moisture in the soil
below the Caliche. If not, then it might not provide a low-impedance
ground even if you could penetrate it!

Fred
K4DII