I generally pass on pool projects since in my experience most pool designs seem to defy rational analysis at one point or another. There are also many non-structural aspects of the design that one must be acquainted with such as water tightness, accessibility, codes governing depth, the slope of the bottom, drain locations, etc. If you are the only design professional involved in the project then you are “the nail that sticks up the highest” and will likely shoulder responsibility for many of these issues.
To avoid new settlement concerns, mass concrete concerns and to save the client money, you might consider 4’+ of sand, a vinyl liner, and a perlite or vermiculite bottom. I recommend consulting a grey haired pool contractor since they will have a lot of experience in the holistics of pool design and construction.
There is some good information here
http://www.schundler.com/swim.htm
Christopher Banbury, PE
President
Ark Engineering, Inc.
Phone: (352) 754-2424
Fax: (352) 754-2412
From: Jim Wilson [mailto:wilsonengineers@yahoo.com]
Sent: Wednesday, September 19, 2007 9:01 AM
To:
Subject: Swimming pool concrete fill
A client intends to fill a 9' deep pool with 5' of concrete to make a wading pool for the elderly. Are there any particular concerns with the mix design to mitigate chemical reactions between pool chemicals and components in the mix? If not, would a simple 3000lb or 4000lb mix suffice? I am thinking that they should place the final 6" in a separate lift to reduce cracking and facilitate finishing.
The client expects to have a cold joint around the perimeter that will need to be sealed. They intend to drain and repaint the pool every year, so maintenance of the joint will not be too great of an issue.
Jim Wilson, PE