| Support posts
hold the cross members and support steel that will, in turn,
support the coping that guides the screeds that forms the bowl
walls. So, support posts are very important. It is
imperative that these be placed accurately and solidly. It
will be easiest if you have a base of at least 16 inches of
clean fill in which to place the support posts. Support posts
can be made from 4 x 4’s or by cutting 2 x 4’s and nailing
them together at a right angle to each other.
Support posts are placed
on 3-feet centers from side to side, with 2-feet centers
between the posts front to back. The term “centers” means
that there is a stated amount of space between the center of
one support member and the next. As example, posts set on
“3-feet centers” means that there is 3-feet of space between
the center of one post and the center of the next post.
Dig the holes for the
support posts 16 inches deep and 10 to 12 inches in diameter.
The front hole should be one foot from the outside edge of the
coping it is to support. The holes can be dug using a manual
post hole digger or various mechanical diggers. The posts
should be square to one another and plumb. Check to insure
this with a carpenter square and level. Place the support
posts in the holes and set them in place using concrete. If
using pre-mixed bag concrete it will take approximately two
bags for every three holes. Allow the concrete to cure
completely before setting the cross members.
Be sure to leave a sufficient amount of the
support post remaining above the line of the cross members.
This will facilitate the removal of the support posts at a
later time. It is easiest to remove the support posts with an
articulated bucket on the front of a back-hoe or by pulling
them out with a logging chain (if the former is not
available). It is important when removing the posts to pull
them straight up. If you do not remove them in this way you
can cause cracking of the freshly poured concrete walls. If
you have any concerns about cracking the walls while removing
the support posts, take the time to dig them out by hand.
Under no circumstances can the posts be cut off and the
concrete and embedded wood allowed to remain in the ground.
The wood will eventually rot, leaving a void that will lead to
cracking or caving.
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