By Peter Sutherland, Tanknology Canada Inc.
Over the past few years, thousands of underground storage tanks have been upgraded to include secondary containment, overfill protection and spill containers. These devices, along with tank monitors, are designed to protect against releases of product into the environment.
With the expense of these upgrades out of the way, tank owners have breathed a collective sigh of relief and considered that their newly upgraded systems were safe into the foreseeable future. This has proven to be a false sense of security because, although tank owners have installed all of the necessary equipment, they have failed to maintain these devices. It is very common to find tank systems where the upgraded equipment has not been inspected or maintained since it was installed.
One prime example of this is in the area of secondary and spill containment systems. It is now mandated in almost every province that all tank systems must have containment around fill pipes, underneath product dispensers and in submersed pump and piping pits. Many of these systems have been in place for five years or more and are deteriorating due to exposure to fuel and weather.
A new law in California recognizes the implications of secondary containment systems that are no longer able to contain leaks when they occur. This new law requires that all secondary containment systems be tested upon installation, six months later, and every thirty-six months for the remaining life of the tank. There is another secondary containment regulation in the state of Florida and other states are considering similar laws.
After a year of testing sumps in California, Tanknology has discovered failure rates between 10% and 20%, depending on the type of equipment tested. For example, one review of failure rates showed that 19% of sumps located under dispensers and 14% of product line containments leaked. These rates were calculated even after some minor repairs were conducted on systems that would have obviously failed the test.
By comparison, an inspection of containment systems in Canada shows that some are full of water, product or a combination of both. Although these systems are designed to contain releases of fuel, they are not intended to contain or store fuel over an extended period. Moreover, many of the components, particularly nitrile rubber boots around piping, may deteriorate in a relatively short time period.
In addition, if leaks do occur, water will flow into the system and there is the potential for releases of product into the surrounding environment. The associated operational problems, such as repeated false alarms from monitoring systems and the potential for environmental releases, are making testing of these sumps a popular practice even in jurisdictions where it is not required by law.
Currently the most popular methods for containment testing involve the accurate measurement of a water level over a short period of time. Normally the containment is cleaned of all debris and residual product using a power washer and detergent. The containment is then filled with water and tested using an approved test method. There are third party approved methods available that use a magnetostrictive level measuring device with compensation for level changes caused by thermal expansion or contraction of the water. These tests are typically conducted within a thirty minute time period and will detect even very small leaks.
Methods and techniques are available for conducting repairs of leaking components. Normally, leaks are discovered at entry and exit points, (i.e., at the point where the piping or electrical conduit enter the containment). Leaking entry and exit boots can be replaced with relative ease. There are also foams and epoxies available to "patch" cracks or leaking seams.
Although it is extremely unlikely that Canadian law makers will catch up with their American counterparts in this area of regulation, many tank owners will recognize that the benefits of a properly maintained system outweigh the costs by a significant margin. The average service station in Canada has between twelve and twenty secondary containment devices. With failure rates of 15%, the risk of an environmental release is significant. Periodic maintenance on all liquid handling equipment is a cost-effective strategy to assure a level of protection against product releases.
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