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Re: CONCRETE: Repair of Segmental Post-Tensioned Concrete Tank

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Bill,
 
Several years ago, there was a failure of a similar tank in Westminster CA.
 
"In September 1998, the 5,000,000-gallon water-storage tank on Hefley Street ruptured, flooding the adjoining fire station and forty-nine Hefley Square Townhouses. There was no loss of life, but damage to homes was extensive. Nearly a year later, eleven of the homes were still being rebuilt or repaired. The fire station was damaged but is back in service. City employees, the Orange County Fire Authority, neighboring fire services and the Red Cross were on-site for days assessing the damage and assisting residents. Water storage for the city was non-existent as the twin storage tank was emptied while the cause of the tank failure was determined." 
 
I do not quite understand what "imminent qualification" means.  However, I would think that any rationally thinking and reasonably experienced engineer can successfully assess the condition of the subject tank and suggest some mitigating measures (for example, retaining of a qualified repair company, like, http://www.cbiepc.com/services/projects/westminster-reservoirs.aspx
 
Looks like that that's exactly what you did.
 
Steve Gordin, SE
Irvine CA
  
 
----- Original Message -----
Sent: Thursday, July 28, 2005 11:45 AM
Subject: Re: CONCRETE: Repair of Segmental Post-Tensioned Concrete Tank

> Bill,
>
> Having some experience with tank design, my biggest concern would be the
> reinforcement that is likely damaged (possibly, beyond repair) by the
> long-time leaks. The subsequent loss of the hoop compression/post-tension
> may be one of the causes of the leaks.

Thanks, I really didn't make myself very clear. That's my major concern as
well.

I know that we can "stop the leaks," but I doubt we can stop the effects
of the damage that has already been done. This is a case of "out of sight,
out of mind." The water tank sits on a back lot. As long as it fulfills
its major purpose, and water comes out when we turn on the tap, we just
don't worry about it. We figure "it's a big, expensive tank, what's to
worry?"

So, no inspection and no maintenance, and this is what you get.

FWIW, I consider myself imminently qualified to assess this tank. But
anyone here who thinks they possess all the wisdom of the world (at least
in our profession), I would ask you: What the heck are you doing here
then?


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