If my math is correct (only took off the left shoe), the LM-470 requires a base
3.5' X 3.5' X 7.5'. that equals a 4' diameter by 7.5' deep hole.
Now I need to talk to the Tower folks and see if they would sign off on that.
There is a local Tree company that I also need to chat with.
73, Dick, W1KSZ
> Date: Mon, 12 May 2008 13:53:37 -0700> From: jimlux@earthlink.net> To:
> w1ksz@q.com> CC: towertalk@contesting.com> Subject: Re: [TowerTalk] Digging a
> 5'x5'x8' tower footing> > RICHARD SOLOMON wrote:> > Let me toss this out for
> consideration. I too have the situation where I need> > a large hole for an
> LM-470 base.> > > > I thought about contacting a "Tree Planter" and getting
> him to use his big> > Auger to bore the hole for the base. I don't think it
> makes much difference> > if the hole is round or square as long as the same
> amount of concrete is> > used.> > > > Or am I totally off base here ??> >
> Nope.. you're right on base. here in Southern California, a lot of >
> structures (light posts, freeway signs, roller coasters, etc.) get >
> installed on what are essentially vertical reinforced concrete columns. >
> Drilled out with a BIG auger, rebar cage dropped in, concrete poured, etc.> >
> Your engineer can tell you what diameter and depth works for your loads > and
> soil conditions.
A lot of times, deeper and smaller in diameter > works better than big and
flat (it doesn't cost much more to drill a few > feet deeper, once you've got
the machine there and set up).> > A fairly common scenario here is upgrading
traffic signals. They'll > jackhammer out the sidewalk on the corner, leaving a
hole inside the > existing curb about 4x4 feet. Drill a 3 foot diameter hole 20
or so > feet deep, then set rebar and fill with concrete. Then, the lamp >
standard gets bolted on top. These have huge canteliever loads (imagine > the
horizontal crossbar spanning 3 or 4 traffic lanes holding up the > signals)> >
> They can do all 4 corners in a morning.> > For smaller jobs, they've got
machines that can do 2 foot piers on a > small skid-steer type carrier (think
crawler drill for blasting) that > you can get through a 5 foot wide gap
between house and fence. I don't > know how deep the little machines can go,
but 10-15 feet is plausible, > but you might have to put an ext
ension on the shaft.> > > > Jim, W6RMK
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