[TowerTalk] Looking for some foundation advice

[jimlux]

On 5/27/20 3:51 PM, Tim Duffy wrote:
> Hi Don:
> 
> I recommend that customers consult with the engineers at the tower company
> when they are thinking about making changes to the designed specifications
> for the foundations.
> 
> There is no room for mistakes or an unsafe installation. Call US Tower and
> let them guide you.
> 
Or hire a local engineer to help - they'll know the local soil types, 
and what works and what doesn't - both from a practical, and a "will I 
get a permit", standpoint.

Off hand, there's no fundamental problem with a concrete base being 
below the water table height - concrete in water just keeps getting 
stronger. Digging and forming is somewhat of a pain, but it's pretty 
common practice in places with high water table and lots of rain. The 
concrete going into the hole is a lot more dense than the water, so it 
displaces the water in the bottom of the hole as you fill it.

But, really, call a local engineer - you may have soil that is squishier 
(bad) or stiffer (good) than the basic design. You may also have 
"expanding clay" to worry about.



> 73
> Tim K3LR
> 
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Don
> Solberg
> Sent: Wednesday, May 27, 2020 6:45 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Looking for some foundation advice
> 
> I was planning on purchasing a used US Tower HDX-572, 72 ft crank up
> tower.  It looks like I may have run into a problem with the foundation.  I
> had some trenching done today for a new well and discovered that the ground
> water level is just slightly lower than 6ft.  US Tower specifications call
> from a 7.5 foot deep hole. My soil is mostly sand, so in addition to not
> being able to go down 7.5 ft, I probably also want to make the foundation
> wider.
> 
> Is it practical to put up the 72ft tower with a wider pad, or should I look
> at getting a smaller 55ft tower?  Another alternative is find another
> location for the tower.  I have about a 10 ft hill on another property that
> I own across a gravel road.  This would most likely eliminate the ground
> water problem but I would have about a 300 ft cable run and I would have to
> trench across the town's gravel road.
> 
> I am looking for recommendations.
> 
> 73,
> 
> Don K9AQ
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