Tracing the Justification for Tracer Testing

This post discusses the use of tracer testing for gasoline station construction in California and argues that, while the regulatory regime is excessive given that its original justification no longer exists, mandating use of tracer testing technology makes sense as long as we are under the current regulatory standards for “product-tight.”

As a laborer in the gasoline station construction industry, I found myself at odds with the then-new regulatory regime enacted by California in 2003. At the time, I blamed California for requiring excessively advanced technology for testing. Tracer testing placed onerous requirements upon construction workers, requiring utmost care in an industry that is by its nature rough and dirty.

When I began research for this post, I expected to find tracer testing to be the culprit for exorbitant costs imposed upon gasoline stations. But though the original justification for tracer testing no longer exists, the regulatory regime, rather than the technology, is responsible for the difficult standards. As long as California retains the current definition of product-tight—including both liquid and vapor—tracer testing is necessary.

Tracer Testing

Tracer testing, also known as inert gas pressure testing, is a form of testing used to find small leaks in containment systems. The containment system is pressurized with the tracer gas (usually helium due to its inertness, small molecular size, and thermal conductivity) and then delicate instruments search for the presence or concentration of the inert gas in the air immediately surrounding the containment system.

Tracer testing is more advanced than traditional air or water-based pressure testing. Under the traditional forms of pressure testing, a containment system is placed under substantial pressure and the amount of pressure lost determines whether there is a substantial leak. Unlike traditional pressure tests, tracer testing detects extremely small leaks, because rather than simply measuring the lost pressure, the presence of inert gas is measured. Extremely small amounts of helium can escape and still be detected, rendering the test able to achieve more exacting requirements.

AB 2481: Mandating Vapor-Tight Standards in California

In 2002, California passed AB 2481, rendering California standards for underground storage tanks stricter than federal standards in several ways. The bill redefined “product-tight,” a basic requirement for underground storage tanks, to include the ability to contain the liquid and vapor of the product, rather than merely the liquid. To meet this new requirement, the bill mandated enhanced leak detection or inert gas testing, as approved by the State Water Resources Control Board. Praxair’s tracer testing was the only test approved by the California Water Resources Control Board for quite a while, and remains the industry-dominant test.

Passing tracer tests was extremely difficult for contractors used to meeting traditional pressure testing standards. Systems that fail tracer tests, and most do, must be inspected and repaired by hand, until they can pass tracer testing. This process is very difficult, as the cracks being dealt with are sometimes not identifiable to the naked eye. The prior testing regime, air or water based pressure testing, still required careful inspection, but any flaw large enough to cause a pressure test failure could be easily found using soap and water. Because tracer tests can discover minute discrepancies, these discrepancies are harder to find and remedy. Requiring tracer testing increased the cost of labor and decreased the pool of specialists who could bring a station into compliance.

MTBE’s Rise and Fall

The original purpose of AB 2481 was “to protect the environment against unauthorized releases of methyl tertiary butyl ether (MTBE).” The legislation was later changed to account for all “unauthorized releases of petroleum, including methyl tertiary butyl ether (MTBE),” but MTBE remained a major motivating factor for the updated containment requirements.

MTBE was a substantial threat for three reasons. First, it poses a greater threat to the water supply than other gasoline components, including petroleum, because it has higher water solubility, allowing it to travel further underground than other gasoline components. MTBE also poses a more substantial water contamination threat than other gasoline components because even trace amounts of MTBE noticeably alter the taste of water. Finally, MTBE has potentially negative health effects. Considering these factors, the concern than MTBE would contaminate the groundwater could powerfully justify stringent regulation of underground storage tanks.

This original purpose no longer exists; MTBE is permanently banned in California and many other states. MTBE was permanently banned in all gasoline sold in California in 2003, the same year AB 2481 began enforcement. Gas station contractors in California are left with an extremely stringent test that requires product-tight containment that prevents even subterranean emission of vapor.

Should California Continue Tracer Testing?

One alternate justification for the regime of testing is extreme environmental caution. Keeping any amount of gasoline out of the ground could be said to be worth substantial investment. If MTBE had been banned before it caused problems in the water supply, perhaps the regulatory regime would have continued to use traditional air or water based testing, but now that the industry has used enhanced leak detection tests for eight years, much of the fixed costs to learn how to pass tracer testing have already been incurred. There are also the continuing costs that come from the enforcement of a strict regulatory regime that does not permit any leakage of vapor.

Many inefficiencies plague California’s regulatory regime of gasoline stations: California-mandated use of phase II enhanced vapor recovery (EVR) in gasoline stations creates more air pollution by conflicting with EPA-mandated onboard vapor recovery. California’s requirement for secondary containment for tank sumps is unjustified because sumps are not a primary containment system that holds product, and California’s use of continuous monitoring systems prone to false alarms has created a cottage-industry around checking false alarms. However, the use of tracer testing does not seem to be one of those inefficiencies. The technology itself is more effective at locating deficiencies than traditional air or water based pressure testing. The need for vapor-tight underground containment is debatable, but so long as California requires it, tracer testing is a justified standard for contractors to employ.


About the Author

Joseph Alm

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