Michael,
I've had a chance to read all these great response to your questions and I don't have very much to add to this conversation.
Anyway, I've been blessed enough to work in many different places around the world and have had the opportunity to work with many different types of pipe materials (VCP, ACP, Concrete (non reinforced, RCP, PCCP), PVC, DIP, Fiberglass, HDPE, etc.). And as you are aware if one designs, installs, operates, and maintains the gravity sewer systems properly (using any of those materials). In the case of VCP a lot of the municipalities that I have worked with generally have issues with VCP and in my opinion I don't necessarily believe its the VCP, our designs and installation practices have improved over time. Many of the failures of VCP have been due to the practices of the those days, for example we now look at the bedding and backfill much differently than before (I'm sure 20 to 30 years from now someone is going to think the things we did today belong in the dark ages as new technologies and advancements happen). All this being said there is a lot of VCP out there today that is still in very good shape and going strong. Again in many of those municipalities they replace (or rehabilitee) their VCP an issue arises. However, when they replace it, it tends to be another type of pipe material altogether. One of the reasons behind this is because they can reduce the number of joints between manholes (laying lengths for VCP can be shorter than PVC, DIP, Fiberglass, etc.) and thus reduce risk of joint failure.
As for your seismic question it's been a while since I've worked in an area like yours but I do know that the National Clay Pipe Institute publishes 100 years and older sewer table and I believe that they state that San Francisco has had a VCP in operation since 1876, one may wish to do a little research on that line and see how it's doing, just a thought. There are others on that list as well that one may wish to do some research on.
Well I've taken up enough of your time.
Have a great day and good luck!
Doug
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C Douglas Jenkins, PE., M.ASCE
Director - Water Networks
Ramboll
Atlanta, GA
770.781.1720
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Original Message:
Sent: 04-02-2019 16:20
From: Michael Tran
Subject: Vitrified Clay Pipe - Modern Use in Sewers
Hi,
I'm trying to gauge what are utilities using for their gravity sewer systems. How often is Vitrified Clay Pipe (VCP) still used? Has any utilities revised old standards to adopt modern materials, such as HDPE? Are other materials considered as a standard? I'm most interested in cities located in seismically active areas.
Thanks in advance for your feedback.
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Michael Tran P.E., M.ASCE
San Francisco Public Utilities Commission
San Francisco CA
(415)695-7372
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