[TowerTalk] Pad and Pier Foundations

[Jim Lux]

At 08:18 AM 7/11/2005, K7LXC at aol.com wrote:
>In a message dated 7/10/2005 10:39:28 PM Pacific Daylight Time,
>towertalk-request at contesting.com writes:
>
> >  The ability to dig an "undercut" hole no doubt depends on the soil. I
>gave a local concrete contractor the AN Wireless foundation plan, and he
>said there was no way to dig such a hole. He said the only way to do a
>pad and pier foundation around here would be to dig the hole the size of
>the pad, construct a form the size of the pier, then backfill.
>
>     A couple of comments about the Trylon base design. First, IMO it's a
>stupid design. I'm sure there's a valid engineering reason to have the bottom
>belled-out but it's not only dangerous to be in a hole that deep but it's 
>also
>illegal per OSHA rules to be that deep in a hole without being shored up. 
>This
>was designed by an engineer in an air-conditioned office that never has to
>install one of them. In many cases the soil won't allow it anyway.

I seem to recall a recent post describing how there are drilling rigs that 
can produce this kind of hole.  That might eliminate the need to have a 
worker in the hole, which as you say, raises all sorts of flags.

The other thing to contemplate is that the base design may have been done 
decades ago, when the risk of inadvertently killing people in hole caveins 
may have been treated a bit more casually.  Safety standards DO change, 
after all, and people have been hand digging wells hundreds of feet deep 
for millenia (and, dying in the process, too).