[TowerTalk] Water table and tower foundation

[Roger (K8RI)]

R. David Eagle wrote:
> Is there any benefit to removing the forms or can one just leave them there for worm food?
>   
With wood nearly all manufacturers state the form must be removed.  They 
prefer you pour into undisturbed soil, but when that is not possible 
forms are required.  That wood may last a very long time and as it 
breaks down (decays) particularly in a wet environment it gets really 
slippery.  Also , rater than the irregular shape of undisturbed soil for 
better "purchase" the sides are straight, offering less grip/purchase. 
Leaving a wood form is like greasing the sides of the concrete.  One 
thing to remember about pouring into wood forms. That concrete exerts a 
LOT of pressure and just nailing or bolting them together will most 
likely fail  They need several levels of reinforcement all the way 
around, particularly at the bottom and mid levels of say a 5 or 6' deep 
form. I'd use at least a 2 X 6 on edge (going all the way around, 
bolted/pinned together at the corners.  These can be a real bear to get 
out of the hole after the concrete has set as usually some dirt falls 
in. Working between the form and the so called undisturbed soil is a 
very dangerous position.  Use temporary shoring to hold back the dirt 
walls.  Try to make some provision for pulling the forms without having 
to get down into the hole.

Construction companies usually use steel forms which of course would be 
too expensive to leave in.

73 and good luck,

Roger (K8RI)
> Dave
> KB8NNU
>
> Rudy Bakalov wrote:
>   
>> Hello,
>>
>> I was wondering if anyone has experience and suggestions for building a rather large foundation (11 x 11 x 5) in a area with high water table.  My builder hit water at 34" and while he has some ideas, I would appreciate thoughts from other hams with real-life experience in this area.
>>
>>   
>>     
> Get a big pump!
> Actually that is just what they do around here.  No pouring into 
> undisturbed soil. They dig the hole and keep it pumped out, place a form 
> in the hole, do the pour, keep pumped out until the initial cure (3 days 
> to a week), remove the forms, back fill, and let set for the final cure.
> At least that's what the construction companies do around here.
>
> Throughout the county the water table runs from a foot to about 3' 
> although it's usually lowest by the end of Summer to mid Fall.
>
> 73
>
> Roger (K8RI)
>   
>> 73 de Rudy N2WQ
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