[TowerTalk] Crank-up base

[Mike Reublin NF4L]

Thanks Steve -
The engineer didn't want to do a formal analysis, and there is no permit involved. Undisturbed soil is what I'd heard, but the HyGain book doesn't mention it. I have no idea how old it is.

Still in Duval, so care is certainly advised. What that means in terms of real life shovel-in-the-ground practice, I'm unsure.

73, Mike

On May 1, 2014, at 11:31 AM, K7LXC at aol.com wrote:

> >  I'm negotiating to get the base for my HG70-HD dug and poured. I have a high water table, soil tends toward sandy, and an engineer said he would be happier if the hole were 10' deep rather than the 7.5' called for in the manual.
>  
> >  The concrete guys I'm talking to want to line the hole with plywood to prevent collapse. One guy who does a lot of big sign installations says he does it regularly, and there would be no stability issues.
>  
> >  I've read several times the pour needs to be into undisturbed soil, no backfill, altho that's not in the manual.
>  
> >  What are the facts?
>  
> Howdy --
>  
>     First, your engineer should be specifying everything - including hole depth. What does it say on your building permit plans? If in doubt - I'd go for making the engineer happy and overbuild it.
>  
>     All the tower specs I've seen call for the base to be poured into undisturbed earth. If you do have to use forms, you'll have to be very careful with the backfilling. Put some in, tamp it down (a Jumping Jack is the way to go), and repeat.     
>  
>     If you're still in Duval County, it's a 95 MPH windspeed zone so I'd be real careful with all aspects of the installation. And pretty conservative with everything.
>  
> Cheers,
> Steve     K7LXC
> TOWER TECH