You have bedrock to help keep your base from settling, and your base is
pinned to the bedrock to keep the lateral forces on the tower from
tilting the base. He has a layer of gravel over a water table deal
with settling, and he has only the weight of the base to withstand the
wind forces on a 90 foot freestanding tower. The AN Wireless towers (I
have one) are spec'd for the foundation to be surrounded by undisturbed
soil ... not air.
My point is that the time to figure out whether something will survive
is before you do it, not afterward. Engineering after the fact is
called failure analysis.
73,
Dave AB7E
Joe - WDØM wrote:
> As I pointed out - similar, but my issue was bedrock, his is water
> table. It's never too late....
>
> 73,
>
> Joe
> WDØM
>
> David Gilbert wrote:
>
>> Your foundation is pinned to the bedrock ... his isn't.
>>
>> It seems to me that the opportunity for N2WQ to properly engineer his
>> installation may have come and gone.
>>
>> 73,
>> Dave AB7E
>>
>>
>>
>> Joe - WDØM wrote:
>>
>>
>>> Hi Rudy,
>>>
>>> My situation is similar, although different. I have an above ground
>>> base but without the water table issues. My problem was bedrock. The
>>> tower has been up for over 5 years without a problem, and has withstood
>>> 90 mph gusts that blew out the windows on my home.
>>>
>>> http://www.wd0m.com/
>>>
>>> Click on Ham Radio, then Tower Project. I hope this gives you some
>>> confidence that it will work!
>>>
>>> 73,
>>>
>>> Joe
>>> WDØM
>>>
>>>
>>> Rudy Bakalov wrote:
>>>
>>>
>>>
>>>> Looks like first post came out very difficult to read so here it is again.
>>>>
>>>> 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 dug a hole, filled it with compacted gravel that is above the water
>>>> table, covered the gravel with very thick sheets of plastic, and inserted
>>>> 2' styrofoam boards around the base. Then we poured the concrete. As a
>>>> result, only about 1.5' of the foundation is below ground, 3.5' are above.
>>>> The overall dimensions are 10' x 10' x 5'.
>>>>
>>>> Now I wonder what are the additional engineering issues we need to address
>>>> to make sure the foundation will last and the 90' AN Wireless tower will
>>>> stay up. 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 foundation
>>>>
>>>> 2) Add extra waterproofing using tar/asphalt-like solutions to make sure
>>>> we have extra protection should cracks emerge
>>>>
>>>> 3) Add styrofoam boards to prevent against freezing (it gets as cold as
>>>> -25F in Ontario)
>>>>
>>>> 4) Backfill around the structure 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 below the mound surface to make sure no
>>>> water gets near the foundation
>>>>
>>>> Any further comments and suggestions will be greatly appreciated.
>>>>
>>>> Rudy N2WQ
>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
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>>>>
>>>>
>>>>
>>>>
>>>>
>>> _______________________________________________
>>>
>>>
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>>>
>>>
>>>
>>>
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>>
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