Was your tower guyed or unguyed? Makes a lot of difference in the
loading on the base. I gather Chuck's would be unguyed, and that
suggests to me that he needs to be very sure of the quality of the
rock. Limestone can be strong or weak (decomposed). A weird example -
50-some years ago, I lived in Hong Kong, right after they built a new
cruise ship terminal. It had two levels, independently supported on
separate columns, and within months of its opening they discovered that
the second level was driving its columns down into the stone at about 8
inches a year. In about 25 years there would have been 6 inches of
headroom on the first floor.
73, Pete N4ZR
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On 4/9/2019 8:53 AM, Hans Hammarquist via TowerTalk wrote:
Hi Chuck,
Bedrock is, I believe, the best to anchor a tower in. Just make 100% sure it is bedrock you have where you are erecting
the tower. When I was planning for my tower a (big mouth) "friend" of mine told me where to find bedrock. He
pointed out a spot that was 100% bedrock. He even "tested" it by kicking on it with his boot. Well, the
"bedrock" turned out to be a relatively large rock, ~100 lb but there was no "bed-" with it. I'm
just happy I checked before I spent the time to attach anything to the rock. I, instead, dug down 5 feet, placed a
6'x6' granite block (that just happened to lay around on my property), and attach my tower to that. As I also had a ton
of scrap metal laying around, I placed that on top of the granite to add some extra weight.
I used 6 galvanized angle irons attached to the granite block with 12
bolts-and-nuts. The bolts all go through the block. The angle irons are encased
in concrete. I felt I didn't have to add any yards of concrete for this
installation. It has been a few years now and nothing has moved.
73 de,
Hans - N2JFS
-----Original Message-----
From: Charles Lind <cxl24@case.edu>
To: TowerTalk <TowerTalk@contesting.com>
Sent: Sun, Apr 7, 2019 7:41 pm
Subject: [TowerTalk] Tower foundation and bedrock
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.
Tnx, Chuck, N8CL
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