he only other time these systems are ever really tested is
if the site has an incredibly high groundwater level that
causes not only the tanks to become completely submerged,
but also the sumps, electrical entry boots, piping entry
boots, and piping, so any leaks allow water to enter a sump and set off
a sensor. Sites with water tables like this do exist, but they are a very
small percentage of all the double-wall sites out there. So, for the
majority of facilities, we don’t even know if this secondary system is
capable of not only containing the leaks, but transporting the leaking product to a sensor to shut things down and set off alarms, as is
assumed they will, the way things are legislated across Canada today.
If you’ve been in the field, you have seen entry boots that are
cracked, split, ripped, and dried out, as well as non-coaxial secondary containment piping leaking or bulk head fittings, electrical entry boots, or sumps cracked or caved in from ground pressure so
badly you can’t even see inside the sumps anymore. And this just
isn’t at a few sites here and there; many sites out there have these
kinds of issues.
The problem we face is there is no easy way to ensure this secondary system is all intact. Although jurisdictions require annual
testing of the electronic monitoring system and sensors and visual
inspection of the systems, I don’t know of any that enforce it. That
being said, it’s not likely a petroleum mechanic, professional engineer, or even the original equipment manufacturer (if they’re still in
business) would sign off that everything is fine and capable of doing
what it is designed to do. Entry boots are impossible enough to see all
the way around to check for any rips, let alone to see if the secondary
containment layer of the pipe between sumps is okay.
The only way to be sure is to reinstall all of the test boots on the
piping system and pressure test the secondary of the pipe, as was
done when it was installed. Then, fill all the sumps with water; however, because you cannot see the outside of the sumps/boots as you
could during the initial hydro test, you have to leave it for at least 24
hours to see if the water level has dropped. Now, assume the water
you pumped out is contaminated, as testing would cost the same, and
dispose of accordingly. Even if the test boots are all in good shape and
fit to re-test, it requires the removal of all dispensers off the islands to
access the sumps and test boots. This typically costs $3,000-$5,000,
and requires a site shutdown for at least two days.
This problem is easily resolved for tanks by “positive” monitoring of the tank interstitial space, either by putting a vacuum on it,
which is the method I have found most successful, or by using a
“ et’s move to
legislate that all
and piping pressure
systems, both new and
existing, be upgraded
to include electronic
line leak detection.
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JUNE 2014 • CANADIAN PETROLEUM CONTRACTOR • 9
2014-06-17 10:57 AM