[TowerTalk] Soil Composition and Tower Bases

[chris]

garyejones at cmaaccess.com wrote:
> The new Qth that I just bought has soil which differs from the dense
> common clay usually found in the soil here in NorthWestern Louisiana.
> This soil has a noticeable percentage of sand mixed in with  the soil
> producing a somewhat more porous soil. There is a pit not far from the
> house where this soil was carved out because I was told it makes
> excellent foundation soil under slab houses, etc. 
> 
> I have checked in the documentation for the crank up towers that I
> have
> and I don't see any information on the soil composition factoring into
> the tower base dimensions. The base is spec'd to be 3 x 3 x 7. Does
> the
> soil composition enter into this picture at all?  The tower is a 70'
> unguyed crank up. 
> 
> The hole will be underdisturbed except for the hole specifically.
> Logic
> seems like I should make the base bigger, but I really don't have a
> clue what I should do, or if I should just ignore that factor. If it
> is
> an important issue, it would seem that it would be factored in in the
> standard base recommendation from tower manufacturers, but I have
> never
> seen it even in fixed tower footings such as Rohn catalog engineering
> specifications. So, that tells me it is probably not important. So, I
> go back and forth. If soil composition is important, how do I figure
> out what to do?
> 
> I certainly don't want to weaken the wind ratings of the tower and
> antenna by whatever I do. 
> 
> Any help or experience on how to deal with this issue would be greatly
> appreciated. 
> 
>                       Gary      W5FI 
> 
> _______________________________________________
> 
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> 
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References are generally made to undisturbed soil.  The first line of 
professional advice would be an engineer.

-- 
Chris, K4AY

In theory, theory and practice are the same.  In practice, they are 
different.