I am going to be putting up about 90' of Rohn 25G tower and had a couple of
questions about guying. This is going to be a temporary installation in a
location which has a leave no trace policy.
Things that make my project different include:
No concrete can be used.
The soil is very dry and fairly crumbly (it's a dried alkaline lake bed)
There will be no antenna at the top, simply a set of lights, so less wind
load.
My plan was to use a Rohn hinged base, nailed into the ground with 3' long
steel nails, assemble the tower on the ground, attach the guys and lights,
then pivot the tower up on the hinge (I've got lots of manpower) and attach
the guys to the anchors, for which I'm considering the Rohn GAS604 4' long
screw anchors.
The anchors are the part that worries me a bit. The ground is not terribly
strong and I'm somewhat worried about the anchors pulling loose. To spread
out the force a bit, I'm considering using an extra anchor on each side, as
shown in the 3k gif here: http://byz.org/~eric/tower.gif. I would guy the
top and middle points to the outer anchor and the middle and bottom to the
inner anchor, meaning that the middle point is anchored twice. Guy AZ is
parallel to guy BY, so the inner anchor is placed about 80% of the height of
the middle anchor point.
Does this seem like it would increase the overall strength of the tower and
reduce chance of failure through anchor pullout? Does anyone have other
ideas or approaches?
Finally, can anyone recommend a good place in the Seattle area to actually
purchase Rohn 25G components?
Thanks
-Eric
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