[TowerTalk] One anchor Hole is not deep enough to Specs (3 feet versus 6 feet deep)

[J. Hunt]

Hi Everyone,
Years ago (20+), was aware of shale rock level ~24" below grade.Rented a Bobcat with hydraulic drill.  
Between the Bobcat and jackhammer, sank post holes ~7' depth, 3' width.Guy posts were covered with Rust-Oleum oil based paint.
The guy posts have steel standoffs welded within the concrete.

Nothing has moved since.  The protective paint prevents rust and concrete contact.
Cheers n 73,JamesKI5DQ
    On Thursday, February 17, 2022, 09:37:44 PM CST, john at kk9a.com <john at kk9a.com> wrote:  
 
 165 foot anchor distance seems pretty extreme to me but I am not the tower
and rotating engineer.

It is easy to visualize guy wire/antenna clearance if you make a simple
drawing showing the side view of the tower and the antenna turning radius in
a CAD program.

What kind of anchor are you using? A Rohn GAC3455 is less than 7ft long and
is usually in a hole 4 ft deep.  If you are not using the standard 80%
location you should adjust the rod angle accordingly. 

I thought I had hard soil!  I would keep using a jack hammer and a back hoe
until you hole that is sufficient depth.

GL,
John KK9A




Steve Lott KG5VK wrote:

My plan is now a Rotating Tower
using the K0XG tower Hardware

Tower is Rohn 45G
140 feet Tall

It will have a KT34XA at 142 feet (short Mast)

A Fifteen meter Stack of Three 5 element beams at heights of
52, 82 and 112 feet

The Rohn Specs show Guy anchors at 112 feet from the base of the tower
However, it was recommended by Richard of K0XG rotating Tower Equipment to
push those guy anchor points out much longer
So, I have chosen 165 feet as the distance to the Guy anchors, Richard say
this will afford me very good guy clearance on my antennas
and an Excel spreadsheet program written by Hal Kennedy N4GG confirms this.

Here is the kicker.............

Once again I have hit Shale Rock in one of my Guy anchor holes
and was only able to get to 3 feet zero inches deep versus the specified 6
feet deep for the anchor holes

I had this issue before with my North Guy anchor on my first tower
at that time I was only 2 feet deep
Back then used the Rotating Hammer drill and the expanding paste and gained
another 6 inches after 6 weeks of work

The solution then was instead of a 1 foot 6 inch pad of concrete in that
hole and then back fill the dirt on top of it, I filled the hole to surface
level with concrete
and have had zero issues, with a very heavy loaded on a Rohn 55G tower
Those guy anchors are 130 feet per specs on the distance.

My question is with the Guy anchors further out (distance) than spec
can I get away with filling the less than spec deep hole once again with
concrete
(versus a 1.5 foot thick pad in the 6 foot deep hole back filled with dirt,
a three foot deep 6x3 by 3 deep, filled to the ground level with concrete)

Someone stated that further out guy distance from the base of the tower
will actually place much more stress on my guy anchors and therefore my
once again plan
may not be viable.

Everyone's thoughts would be appreciated

Steve
*KG5VK*
Tele 318-470-9806
ARRL NTX Section Manager
*Please note: My Out Going Email address is LottsPhoto at Gmail.com*
*KG5VK at ARRL.ORG <KG5VK at ARRL.ORG> is forwarded to my Gmail address*

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