Instead of relying on the undisturbed earth to hold your tower in position,
you are basically relying on a 60,000 pound weight with a 10 foot square
footing to hold up a 90 foot tower. Since this is a drastic change from
the tower manufacture's design, you should not erect your tower until your
have an engineer evaluate your tower base. It's unfortunately that you have
gone this far with the project and probably spent thousands of dollars on
this base, but you can loose much more if it should fail. There may have
been other solutions or ways to install a base below the water table.
Perhaps AN Wireless can assist you with the base design?
Subject: [TowerTalk] Engineering advice on above ground foundation
From: Rudy Bakalov
Date: Fri, 5 Jun 2009 11:41:58 -0700 (PDT)
I have a rather complex situation that certainly can benefit from
the collective wisdom and experience of this reflector.
My property has a very high water table and as a result my builder and I
decided to build the tower foundation mostly above ground. Specifically, we
a hole, filled it with compacted gravel that is above the water table,
the gravel with very thick sheets of plastic, and inserted 2' styrofoam
around the base. Then we poured the concrete. As a result, only about 1.5'
the foundation is below ground, 3.5' are above. The overall dimensions are
x 10' x 5'.
Now I wonder what are the additional engineering issues we need to address
make sure the foundation will last and the 90' AN Wireless tower will stay
Currently, we have identified the following next steps:
1) Waterproof the concrete using silica based solutions, such as Penetron,
Xypex, etc. as permanent solution against water getting into the
Add extra waterproofing using tar/asphalt-like solutions to make sure we
extra protection should cracks emerge3) Add styrofoam boards to prevent
freezing (it gets as cold as -25F in Ontario)4) Backfill around the
to create a mound that takes the rain and melting snow water away from the
concrete. I have also proposed we layer more plastic sheets about a foot
the mound surface to make sure no water gets near the foundation
Any further comments and suggestions will be greatly appreciated.
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