[TowerTalk] Screw in anchors

[Bob Shohet, KQ2M]

Hi Jeff,

My qth is at the top of a heavily forested hill on uneven and jagged ledge with wetlands, ravines, etc.  It is a nightmare to do tower work here.

I have dealt with all the issues you describe for the past 20 years.  Let me offer you some suggestions based on my experiences with putting up and maintaining 2 Rohn 45 towers at 100’ and 130’.

1) Be prepared to clear out a LOT of trees.  I did all the chainsawing down and cutting up myself.  If you like wood fires you will have enough for many years.  If you don’t want to do the work yourself, then spend the money to hire a good local Tree service that will charge you reasonable rates and have them do all the work – cutting down, cutting up and/or hauling away.

Depending on the community, there may be some loggers that will either take some of your trees down gratis – for the wood – or may pay you for the trees once they are taken down.  This could reduce your overall cost and reduce the amount of work you need to do.

2) Yes, hire a competent local backhoe operator.  They can get their backhoe into narrow areas between trees, around ledge etc.  They also cost less than larger machinery.   Have them dig ALL the holes for the towers and guy anchors.  I used the 7’ Rohn guy anchors with 5-hole equalizer plates.  My advice is DON’T use screw-in anchors.

3)  It was impossible to get a concrete truck to the holes for the tower bases and guy anchors.  Not a problem.

I hired the same competent backhoe operator.  We had the concrete truck maneuver his chute to the top of the ledge where one of the concrete truck guys used a shovel to push the concrete down the chute and into the front loader bucket of the backhoe.  The backhoe operator then turned around and slowly maneuvered around the ledge and trees and trucked the concrete to the holes where he dumped it in.  This process was repeated about 8 times over the next 1 1/2 hours.  At the holes, the other concrete truck guy then spread and smoothed out the concrete over the rebar cages that I and N1MM had built.

I used up about 2 cubic yards of concrete for the 2 tower bases and 3 guy anchor holes – which were all unusually deep and wide thanks to all the boulders and debris that he kept digging out of the hardpan and rock mounds on the ledge.

4) All the work was completed in 3 hours including all the pouring and smoothing of the concrete.

The concrete (20 years ago) cost $1,050

The backhoe operator cost $200 to dig all the holes on the ground and up on the ledge and another $150 to haul and dump the concrete.

I live in Western CT so nothing is cheap here.  But it was money well spent to have highly competent people do the specialty work that I would not have done nearly as well.  I save money by doing did all the weeks of chainsawing and lost weight and put on muscle in the process – a side benefit.  If you are not into physical work or you are not healthy enough, spend the money to have a small professional and insured Tree crew do it for you.  They can probably get it all done in two days for two tower worth of work with a few chainsaws and a log chipper.

20 years later, my 2 towers have remained unscathed through Hurricanes Sandy (110+mph wind gusts) and Irene, and F1 and F0 tornado direct hits and countless episodes of straight-line winds, ice-storms and blizzards with hurricane force wind gusts.  I never worry about the earth anchors.  I would however worry if screw-in anhors would have stood up to the storms here.

GL and 73

Bob, KQ2M


From: Jeff Whisler 
Sent: Tuesday, March 13, 2018 11:49 AM
To: Bill via TowerTalk 
Subject: [TowerTalk] Screw in anchors

All,

I am rather new here.

I did put up 60 feet of Rohn 45 many years ago so I am not a complete
novice.

I am planning to erect a 70 ft Rohn 25G tower this summer.  The location is
very remote and heavily wooded.  The location makes using conventional cast
in-place re-enforced concrete anchors difficult and very expensive.  I
might be able to get a mini-excavator in to dig but I would certainly have
to use a pump truck to get the concrete in place.  $$$

I did have a comprehensive soil evaluation done for a conventional septic
system when I built the home in 2013.  In the area tested it perked for a
conventional system.  When they excavated for the foundation however they
found heavy clay and rocks.  Same when they drilled the well.

I am considering using AB Chance screw anchors or perhaps "Bust" anchors.
I realize that the book calls for the cast in place option but I am afraid
that will not be affordable.

Any constructive thoughts (pun intended) pro or con or other anchor ideas
would be most appreciated.

Jeff

WV9X--
J Whisler
262-623-7450