[TowerTalk] Crank-up base

[Kimberly Elmore]

I did exactly this with a base for my Rohn HDBX48 tower. The plywood will slowly decompose and as it does, soil will filter in to take its place. For all practical purposes, it all remains "undisturbed." What the tower engineers do not want is for the base to be sunk into fill dirt -- that won't be stable and you will likely have stability problems (the base may wobble with time such that your tower is no longer vertical). 

With sandy soil and high water table, you risk having the hole walls collapse into the hole, which changes lots of stuff you don't want changed and violates the "undisturbed soil" requirement.  

Kim N5OP


________________________________
 From: Mike Reublin NF4L <nf4l at comcast.net>
To: towertalk reflector <towertalk at contesting.com> 
Sent: Wednesday, April 30, 2014 7:20 PM
Subject: [TowerTalk] Crank-up base
 

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?

73, Mike NF4L


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