[TowerTalk] Questions. Was: Photodocumentary of the W4XN TowerInstallation

[JC Smith]

Concrete prices seem to vary all over the place.  Out here in the SF Bay
area it currently runs $120/yard for the "regular" stuff and $132.50 for six
sack - 3/4  (4000-psi) mix.  Pumps are typically $100/hour + $3/yard with a
3 hour minimum.  A friend in San Juan just paid $84/yard (with a $49
delivery charge) for 3000-psi mix.  Pump rent was $175.  Big difference.

On a tilt-over tower the bracket is positioned so the tower lays down where
you want it.  Orientation relative to the pad shouldn't matter as long as
your base bolts stay contained completely inside the rebar cage.  We used
the roller method to move a TX-472MDP a few years ago.  It worked well
(moderately level ground).

For this type of foundation, consider drilling a cylindrical hole vs. the
square one.  It is real hard for a backhoe to dig a narrow, square hole that
is very deep.  A big drilling rig (IF you can get it into location) can dig
a real deep hole in normal soil in a matter of minutes once it's set up.
Check with the CE for your particular project, but when I installed a UST
foundation the engineer said either a square hole or a round hole with
diameter equal to the side of the square would be good.  Obviously, the
square holds more concrete, but the foundation weight isn't the main thing
supporting it.  If you want (I did) it is easy to go deeper with the
drilling rig.  You probably won't use their minimum time (usually a 3-hour
minimum) no matter how deep you go.  Then you can put the concrete that
would have been in the corners of the square into the bottom of the hole and
for the same cu. yds. you'll have a stronger foundation.  Also, I've found
round rebar cages easier to build (use a conduit bender for the hoops), and
they are probably cheaper to have built as that is the way they do most
foundation piers.

Just food for thought.

73 - JC, K0HPS


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of Alan NV8A
Sent: Wednesday, September 06, 2006 7:50 PM
To: towertalk reflector
Cc: DrD at 2020.com
Subject: [TowerTalk] Questions. Was: Photodocumentary of the W4XN
TowerInstallation

1. I am still waiting for the contractor to come by and give me a price
for the foundation for an HDX-555. Although I know that costs can vary
from place to place, may I ask how much it cost to construct your
foundation, including excavation, building the cage, and pouring and
finishing the concrete? Mine will be smaller anyway (6.5 cu. yds.), but
the cost for yours would give me a ballpark figure.

2. I notice that the hole ended up oversize and would thus have needed
more concrete than planned. Who bore the cost of the extra concrete?

3. I notice that your base plate is not square with the hole and the
cage, as shown on US Tower's Web site. Why?

4. How hard a job was it to move the tower on those PVC rollers? How
even was that grass surface?

73

Alan NV8A


On 09/06/06 09:51 pm Dr M J DiGirolamo wrote:

>     Many of you have been following my ham radio tower erecting project
since it
> began back in May, 2006.  I have promised all of you photos and the
project
> photos to date are now posted for viewing.  The most recent Cadweld joints
shown
> were made today, 9/6/06.  I will be adding a few final photos later this
month
> as completion approaches, God willing!
>
>     You can view the photo documented project by clicking on or pasting
the
> following URL into your browser:
>
> http://new.photos.yahoo.com/drd_007/albums
_______________________________________________



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