[TowerTalk] Crank-up base

[K7LXC--- via TowerTalk]

>  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