The biggest problem, Richard, is when the temperature gets much below 32
degrees, the water will freeze, and in the process, expand with enough
pressure to rubture the tubing of the tower legs! I've seen vertical splits
and bulging from freezing many times on various installations. This is not
pretty and nearly impossible to repair and maintain original strength. It
could actually cause the tower to collapse once it thaws! This is a
situation not to be ignored.
One sure fire approach would be to have a masonry drill, nearly the size of
the leg inside diameter, welded to an appropriate extension and drill out
the "plug" through each affected tower leg.
At this point, you might first try inserting a piece of rebar, a foot or so
longer than the total tower section into each affected leg and attempt to
drive the "plug" out of the bottom. If the concrete didn't work its way too
far up the leg, or too far into the gravel bed, this may work.
If this is unsuccessful another alternative is to drill a couple of
5/32"-3/16" drain holes in each affected leg, as close to the concrete as
you can get, and check that these holes remain open every couple of weeks by
inserting something into these holes and/or observing actual drainage. (They
WILL periodically plug up, and you'll not want to ever let this happen,
especially when subjected to freezing temps.)
You'll also want to apply some tar from the bottom of the holes to to
concrete, encapsulating the entire exposed leg, below the holes, to retard
the rusting of the leg/s at this point from the (more present) moisture.
(Thats always a good idea anyways where the legs go into the concrete.) 73 &
Good Luck, -=Rog-K9RB=-
Don't let the callsign fool ya.....I'm in Northern Florida, where the
temperature got down to 24 degrees on two mornings this past winter. So I'm
sure you experience freezing temps. in Virginia too!
-----Original Message-----
From: Richard Eckman <ko4mr@arrl.net>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Wednesday, April 14, 1999 8:55 PM
Subject: [TowerTalk] Tower base drainage problem
>
>I recently installed a 30' Universal tower. Before pouring the concrete
>into the appropriately sized hole, I added several inches of crushed rock
>to the bottom of the hole for drainage of the base legs. Sometime after
>pouring the concrete, I noticed that two of the three bases legs (which are
>largely embedded in the concrete) were not draining. I could see water in
>the legs nearly up to the top, just below where the hinged base attaches to
>the bottom tower section..
>
>I'm assuming that in pouring the concrete, the contractor and I somehow
>managed to get some of it under the legs, even with the several inches of
>drainage rock, thus preventing adequate water drainage.
>
>My question is whether anyone has a feeling of how serious a problem this
>lack of water drainage is. Will this prolonged exposure of the steel legs
>to water likely cause any structural integrity problems?
>
>Richard Eckman KO4MR
>Hampton, VA
>ko4mr@arrl.net
>
>
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>
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