> So I have been trying to put up a 50' 25G tower for a little while now.
I bought some 6'x8" screw anchors thinking they'd go into the clay soil
pretty easily, and they do...for about two feet. Then they hit rock; I
am pretty sure it's bedrock or something similar from talking to my
neighbors. Obviously that's hardly enough earth for a screw anchor to
hold on to.
> What are my options here? Looking at Rohn's drawings, I am entirely
sure
that going down 4' for a concrete base is out of the question. I am
currently thinking I'll bust a hole about 8" around down maybe 3', dig
an angled trench for the bar of the screw anchor, and set it in the hole
with a bag or two of concrete. Hand digging that hole doesn't sound fun,
though.
If it's solid rock and not shattered, you can drill into the rock.
Epoxy in some rebar in the holes. They should stick up some distance. You can
make a form and pour concrete thus joining the bedrock and the concrete. A
2' high cube might be enough for the anchor encasement. A yard of concrete
weighs 4000# so some significant portion of that should be sufficient. Real
engineering comments anyone?
For shattered rock, your plan sounds fine. 50' of 25G won't create a
lot of stresses but over-engineering in any case is highly recommended.
Cheers,
Steve K7LXC
TOWER TECH
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