[TowerTalk] Guy anchors in shallow soil

[K7LXC--- via TowerTalk]

>  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