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RE: Effect of swimming pool on retaining wall

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I have had the pleasure and pain of funding two in-ground gunite pool
projects.  The first was in my backyard in 1978.  The second was in my
other backyard in 1989.  Both projects turned out well, but the only
quality assurance was that provided by the owner (me).  Residential
swimming pools are not engineered by anyone, at least not in a formal
way.  They certainly are not designed as structures.  The irregular
(shape, thickness, reinforcement) concrete shell is not designed for
lateral loads.  It is dependent on surrounding soils to withstand
hydrostatic pressure inside the pool, and vice versa.  This works most
of the time, but not always.  If the surrounding soils are highly
expansive clays and start to swell, all bets are off.  This caused a 40
foot longitudinal crack down the center of my first pool, which allowed
leaking water, which supported further swelling.  Not a pretty picture.

I concur with what Jordan has written below.  Do not expect the pool to
reduce lateral pressure on the nearby retaining wall, and do not rely on
the retaining wall to support the pool.


Stan R. Caldwell, P.E.
Dallas, Texas

Does the War on Terror constitute World War III?
Experts agree:  No ... not until France surrenders.

-----Original Message-----
From: Jordan Truesdell, PE [mailto:seaint1(--nospam--at)] 
Sent: Friday, July 28, 2006 2:52 PM
To: seaint(--nospam--at)
Subject: Re: Effect of swimming pool on retaining wall

Going back to first principles, The lateral pressure from a swimming
pool should be counteracted by the passive pressure of the surrounding
soil. If there isn't enough soil between the pool and the retaining wall
to provide a full passive wedge, I'd say you've got problems. The good
thing is that such an analysis shouldn't be difficult. The bad thing is
that I've never applied the above analysis is real life and don't know
for certain whether it fully applies or whether there are unforseen
complications with the theoretical model. ;-)


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