I just dug (actually my son did) a similar hole for my HDX555 last October.
It can be done with a "rented for the weekend" (the cheapest way)
mini-excavator with no problems except, while operating our excavator, you
could not see the last foot or so of the hole. I helped my son to guide the
last foot of digging. But it is possible. We ended up making the hole
slightly deeper (8 ft.)
than needed. We did do some minor hand work on the walls to make
them pretty and vertical. We ended up dumping in almost 9 yards of concrete.
I don't like the backfill idea. I think the tower manufacturer says
undisturbed soil.
Roger
----- Original Message -----
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
To: "Scott McClements" <kc2pih@gmail.com>
Cc: "Towertalk Reflector" <towertalk@contesting.com>
Sent: Monday, May 12, 2008 2:25 PM
Subject: Re: [TowerTalk] Digging a 5'x5'x8' tower footing
> Scott McClements wrote:
>> Hi,
>>
>> I am in the process of trying to find a excavator to dig the footing
>> for my HDX572 tower. To the 5 people I've talked to so far, this
>> 5x5x8 hole is difficult. I think mostly because none of them have a
>> small enough backhoe. Most of them want to dig a big hole and have me
>> pour into a concrete form and backfill later.
>>
> The problem might be getting one with enough reach into the small hole.
> Plus they are probably used to doing the dig and form approach instead
> of pouring into undisturbed soil. In some areas it's almost impossible
> to pour into undisturbed soil. On one side of my yard it's difficult
> to dig a hole with steep sides. On the other you could did one and
> park a truck on the edge of the hole with no problem.
> http://www.rogerhalstead.com/ham_files/tower12.htm shows a small backhoe
> that just barely had enough reach roughing out one of the guy anchor
> holes and he had to reposition to get it all. He would not have been
> able to get below 5'
>> They claim they can backfill and bring the soil back into
>> "undisturbed" condition around the footing by compaction - even
>> claiming that this might be more reliable than just digging a hole
>> just to the size I need.
>>
>> I am lining a couple people up for estimates, but I think this already
>> sounds like the are trying to wring a couple days of work out of this
>> - maybe I am wrong here. I have even have one person decline giving an
>> estimate altogether. Should this be an easy task for a skilled person
>> to dig on a mini-excavator? I was told that if the hole is deeper than
>> 4', that no person can enter it unless walls are built up.
>>
> Depends on regulations. I've forgotten what the federal regs are now.
> Small, deep holes are risky. In some soils it's the risk of cave in
> (we had that happen when we dug up our weep tile) and in others it's
> the risk of insufficient oxygen. In the early days I used to work on
> instruments down in holes at "the plant". By the time I went back to
> college you couldn't even enter one of those places without a two man
> crew outside the hole while I had to wear a harness so they could pull
> me out just-in-case.
>
> Roger (K8RI)
>> Any ideas?
>>
>> -Scott, WU2X
>> _______________________________________________
>>
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>
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