Having just drilled a well nearby, I can tell you the rock is solid at least
300 feet. My well had to go down 400 feet to get into the aquifer. The local
blaster has also told me the rock is solid and very strong.
Les
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of John W2iD
Sent: Thursday, February 16, 2006 2:58 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] UST HDX589 crank-up tower base on rock?
I'm following this thread and wondering: Surely it must matter how thick
the rock is. How does one tell accurately how thick is the rock? And is it
possible that a rock of unknown (and uncontrollable) mechanical soundness
turns out to be less "solid" than it may originally appear, i.e. less sound
than a known (poured) block?
Wondering because when it comes time for me to finally start digging, I
expect to hit rock immediately as well.
John
W2iD
(Stuck in the ZBA appeal process for 12 months and counting...)
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Les Kalmus
Sent: Thursday, February 16, 2006 2:34 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] UST HDX589 crank-up tower base on rock?
That's exactly the point. I don't want to blast a hole in the rock and then
fill it up with concrete. I want to anchor the tower base to the rock with
only enough concrete to come a few inches above grade. My concerns are the
following:
-How much up force will the anchors handle? There will be a lot of leverage
produced by the wind on the tower.
-How deep into the rock should I go? A few inches doesn't seem to be enough
given the winds and exposed location on top of the hill.
-The "T" base of the tower is drilled for three pairs of one inch bolts. Can
the holes in the rock be aligned accurately enough for the bolts to slide
through the base holes easily? If a pair of holes are drilled a few inches
apart will the rock between them still retain its strength?
-Normally, in concrete, J bolts are used and tied to the rebar in the
footing. I guess I would need longer threaded rods with whatever is used to
anchor them to the rock on the bottom end.
Les
-----Original Message-----
From: K7LXC@aol.com [mailto:K7LXC@aol.com]
Sent: Thursday, February 16, 2006 10:16 AM
To: towertalk@contesting.com; w2lk@earthlink.net
Subject: Re: [TowerTalk] UST HDX589 crank-up tower base on rock?
In a message dated 2/13/2006 3:17:48 A.M. Pacific Standard Time,
towertalk-request@contesting.com writes:
> Hi TTians,
> In a few months I will be starting construction on a new house which
will be
located on top of a hill on a adjacent piece of property. My HDX589 is
currently installed on the manufacturer's recommended base of 5x5x8.5
feet
of concrete with rebar.
> Test holes in the vicinity of the new house have revealed between 16
and 40
inches of soil on top of the rock the hill is made of. A blasting
contractor
has told me that the stone is very strong and stable and he will not
have
any problems blasting for the house basement and foundation.
> I won't be able to dig another hole and use the same method as the
current
location. Instead, I have been told there are bolts or rods that can be
set
into holes drilled into the stone and epoxied in place which can support
the
tower.
> I will probably need an engineer but don't know where to begin to
find one
familiar with this type of work or what alternatives exist. Anyone
familiar
with this technique or alternative method who can steer me in the right
direction? Any particulars I need to provide to him/her that I need to
research in advance?
Well, getting an engineer's blessing is always a good idea. Maybe
you can talk to a couple and get some off-the-record feedback on what you've
got and what's possible.
I would be in favor of using the rock as the base and then you only
have to use a little concrete to get the top of the base a little above
grade. Why would you dynamite out a bunch of rock and then fill in the hole
with concrete when the rock by itself would accomplish the same thing?
You can rent a rock corer to drill the appropriate holes for the
factory anchor bolts - or have someone come out and do it - and then you can
epoxy them in or use rock expansion bolts - or both. It'll be real strong.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for amateurs
Cell: 206-890-4188
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