[TowerTalk] [Bulk] Guy anchors in shallow soil

[Grant Saviers]

My Rohn catalog says 2'6" deep for the base and 4' for the guy 
anchors.   I'm guessing you were trying to drive the screws by hand, a 
machine that pushes and turns them in may make a big difference. 
Otherwise, a small or mid-sized backhoe or mini-excavator probably will 
dig deep enough unless the rock is granite.  Check your local rental yard.

If not, then engage a PE for a spread footing design.  Enough mass of 
concrete can work at very shallow depths.

Your trench idea seems way too little IMO.

Grant KZ1W


On 8/30/2014 3:27 PM, Linux Mercedes wrote:
> 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.
>
> For what it's worth, I'm in central Missouri.
>
> Thanks!
> --Nathan
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