Rod,
The electric utility industry is faced with the same problem when they
install towers for transmission lines. The standard practice is to drill a
hole into the rock, perhaps ten feet or so, and drop a 4/0 stranded copper
wire down into it. The hole is then filled with a slurry made from sodium
Bentonite clay. This clay is also called Montmorillonite. Its great
virtue is that it expands in the hole, essentially making the 4/0 wire much
larger in surface area and ensuring a low-resistance connection to Mother
Earth. The enormous pressure developed as it expands causes the rock to
fracture and make more pathways for current.
This was exactly the way a good grounding system was created for a nearby
(at Vandenberg AFB) rocket launch pad that was constructed in an area that
is mostly granite rock a few feet below the surface. The Bentonite can be
purchased in pellet form from any company that supplies the petroleum
drilling industry. It's the stuff used to plug wells once they've been
pumped dry.
73, Eric Lemmon WB6FLY
[EMAIL PROTECTED] wrote:
> Hello to the list and here is my question. The repeater site I am
> working at has little dirt and lots of rock. I have to use a jackhammer
> for the fence post holes, I can't hardly wait - ha ha. What are your
> thoughts? What have you done, if faced with the same problem. If
> this topic has been beat like a dead horse, let me know and I will go
> dig thru the archives. Thank you.
>
> Rod KC7VQR
>
>
> Yahoo! Groups Links
>
>
>
>
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