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Re: [TowerTalk] Tower foundation and bedrock

To: Charles Lind <cxl24@case.edu>, k7lxc@aol.com
Subject: Re: [TowerTalk] Tower foundation and bedrock
From: Grant Saviers <grants2@pacbell.net>
Date: Mon, 8 Apr 2019 17:35:20 -0700
List-post: <mailto:towertalk@contesting.com>
Since soft rock may not be strong enough in tension for grouted or epoxied anchors, perhaps a bit of caution or maybe some consultation from a soils engineer. Anchors are A+ in solid granite and cured concrete. We had some holes drilled with an air powered drill + trailer compressor in Adirondacks granite to anchor a cantilevered deck over a lake.

Grant KZ1W

On 4/8/2019 13:41 PM, Charles Lind wrote:
Tower talk has been great for ideas.  The property is in the general area
of a limestone quarry, and the owner, my brother-in-law-says he has never
been able to get more than 3 to 4 feet before hitting rock.  The good news
is he has an excavator, so soon we will make a trial dig to see how deep,
and how solid the limestone is.  If the rock is solid and at least 3 feet
down, I like the idea of epoxy and big rebar.  If the rock is in chunks,
then the dig goes on!!

On Mon, Apr 8, 2019 at 12:32 PM <k7lxc@aol.com> wrote:


  I have the opportunity to put up a TX-455 tower on the property of my
brother-in-law:  200+ acres and no zoning issues.  He says, however, that
there is limestone bedrock about only three feet down.  Before I start
Digging pilot holes, is there any advice a how to proceed with providing a
solid foundation if this is the case.

     What sort of shape is the bedrock in? Is it shattered? How big are the
pieces?

     If you have to use "extreme" techniques to get the bedrock out, why
are you removing it? You want your tower to have a 3000 PSI concrete base
and most rocks are equal to or more to that. Why excavate a hole of heavy
material and then refill it with different heavy material?

     If this was my installation, I'd drill holes into the bedrock, epoxy
in a bunch of rebar (you could even use a concrete adhesive to bond the
rock and the concrete) and then fill the 3' hole with concrete with the
anchor bolts in it. Voila! A yard or two of concrete and you have a 100%
reliable, simple and cheaper tower base. I'm just saying.

Cheers,
Steve     K7LXC
TOWER TECH-
Professional tower services for amateur and commercial
Cell: 206-890-4188

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