Allan BlanchardUncategorized

What is the Lifespan of an Underground Storage Tank?

These two tanks were both installed in the 1970s. They had vastly different levels of corrosion. They also had massively different costs to resolve environmental issues!

 

Modern-day USTs used for the purposes of storing fuel are composed of one of two materials; steel or fiberglass reinforced plastic. There are advantages to each material plus there are regulatory changes and upgrade requirements that affect the practical lifespan of USTs.

 

Steel Tank Lifespan

Corrosion experts attribute different rates of deterioration of steel tanks to a multitude of factors including:

  • Quality of the steal
  • Geology
  • Soil type
  • Soil moisture
  • Tank pit backfill material
  • Presence of metal in nearby soils
  • Dissimilar metals in UST system components
  • Use of dielectric coating
  • Use of cathodic protection systems

 

 

Fiberglass Tank Lifespan

Typical warranted lifespans of fiberglass reinforced plastic (FRP) tanks are 30 years.  There is concern that insurance companies may begin to get nervous after 25 years!  The lifespan of an FRP tank depends mainly upon how it was constructed and installed.

  • Single wall vs double wall
  • Installation procedures
  • Backfill materials (presence of sharp stones/rocks)
  • Buoyancy issues
    • Tie downs in high water table areas
    • Amount of product in tank if backfill becomes saturated
  • Improper venting

 

Steel Tanks vs Fiberglass Tanks

Steel is stronger and more rigid than fiberglass, which makes installation easier.  Sites with heavy equipment onsite may have surface compaction issues that result in tank deformation. Sites that experience high water tables or flooding may lead to ground and tank backfill saturation that result in breaches caused by buoyancy issues.

Both steel and fiberglass tanks require backfill, but steel tanks don’t need the backfill to provide supplemental structural support like FRP tanks. Therefore, backfill for steel tanks is usually less expensive than fiberglass tanks. The domed ends of fiberglass tanks make them longer than flat-end steel tanks; so, if a property has limited space for a tank field, tank shape also may be a consideration. In most cases, installation costs for steel tanks are lower than fiberglass tanks.

Generally, FRP tanks are known for their ability to resist corrosion in all types of climates. That being said, some steel tank fabricators construct their tanks with a fiberglass or other type of corrosive-resistant armor or lining which provides an extra level of protection between the steel structure of the tank and the environment surrounding it.

 

Material Compatibility in Older Tank Systems

The ethanol to gasoline ratio in common use today (approximately 10%), required to meet the 1990 Clean Air Act requirements, poses no problems for most modern UST systems. However, higher ethanol, E85 for example, may create cause for concern.  Various soft metals (aluminum, brass, zinc) are incompatible with E85. Many components constructed of these metals are common in UST Systems. In addition to soft metals, many non-metallic materials may undergo accelerated degradation due to ethanol exposure. These materials include natural rubber, fiberglass adhesives, polyurethane, and various polymers/elastomers used in flex piping, bushings, gaskets, etc. Some states have regulations that require a UST system that will store E85 to be certified compatible with E85 by the manufacturer or by Underwriters Laboratories

 

Tank Upgrade Regulations – Impact on UST Lifespan

Irrespective of lifespan expectations for the type of tanks are evolving regulatory update requirements. Every state, and sometimes areas within states, have different regulations.  At a minimum, states must meet federal regulations.

1988 Federal Requirements – Regulated UST systems that were constructed of steel and installed before December 22, 1988, had to be upgraded to meet one of the following corrosion protection options (or be properly closed):

  • Interior lining,
  • Cathodic protection, or
  • Internal lining combined with cathodic protection.

NOTE: Prior to adding cathodic protection, the integrity of the tank must have been ensured using one of the following methods:

  • The tank was internally inspected and assessed to ensure that the tank was structurally sound and free of corrosion or holes.
  • The tank had been installed for less than 10 years and used monthly monitoring for releases.
  • The tank had been installed for less than 10 years and was assessed for corrosion holes by conducting two tightness tests–the first occurring prior to adding cathodic protection and the second occurring 3 to 6 months following the first operation of cathodic protection.

All USTs that were installed after December 22, 1988, had to meet one of the following performance standards for corrosion protection:

  • Tank and piping completely made of noncorrodible material, such as fiberglass-reinforced plastic
  • Tank and piping made of steel having a corrosion-resistant coating and having cathodic protection
  • Tank made of steel clad with a thick layer of noncorrodible material (this option does not apply to piping)
  • Tank and piping are installed without additional corrosion protection measures provided that a corrosion expert has determined that the site is not corrosive enough to cause it to have a release due to corrosion during its operating life and owners or operators maintain records that demonstrate compliance with this requirement
  • Tank and piping construction and corrosion protection are determined by the implementing agency to be designed to prevent the release or threatened release of any stored regulated substance in a manner that is no less protective of human health and the environment than the options listed above

2015 Federal Requirements – Not later than April 11, 2016, all new and replaced tanks and piping must meet the secondary containment requirements, including interstitial monitoring, according to the new requirements for secondary containment. EPA considers piping replaced when 50 percent or more of the piping is removed and other piping is installed. In addition, owners and operators must install under-dispenser containment for new dispenser systems.

The 2015 UST regulation changed certain portions of the 1988 underground storage tank technical regulation in 40 CFR part 280. The changes established federal requirements that are similar to portions of the Energy Policy Act of 2005. In addition, EPA added new operation and maintenance requirements and addressed UST systems deferred in the 1988 UST regulation. The changes:

The new federal regulations put more responsibility on owners and operators – to know what is expected of them at both the state and federal levels.

 

What if my Tank has Reached Its Lifespan?

UST replacement represents an opportunity to upgrade equipment and address future fueling business objectives.

Equipment manufacturers are addressing the importance of secondary and even tertiary containment systems and corrosion prevention in new product releases. Suppliers are redesigning components such as fittings, spill containers, manholes and tank sumps to eliminate potential leak points. Advances in automated tank gauging and leak monitoring systems have greatly reduced environmental impacts from spills.

Tank Installation Expert

If you choose to replace your UST system, seek the advice of a trusted advisor to explain spill prevention and tank construction options.  The right solution for a given fuel site will help eliminate the early replacement of damaged or failing UST components.

Tank Removal Expert

The complex aspects of tank replacement require project planning and specific expertise.  A tank removal expert can help guide you with:

  • Compliance with state and local regulations
  • Early identification of potential environmental issues
  • Contractor licensing requirements
  • Soil and equipment staging
  • Required reporting and remediation

For a more detailed discussion of tank replacement procedures, see my article Understanding the Tank Removal Process.

Determine Future Fueling Requirements

Technology advances such as hydrogen fuels or rechargeable electric vehicles are on the horizon. As I write this article, CA is set to vote on a measure to ban the sale of new gasoline powered cars and SUVs after 2035. Technology advances and/or government mandates may make your new tank investment obsolete before the tanks reach the end of their useful life. Consider interim fueling options such as those provided by Booster to bridge the gap between tank removal and selection of long-term fueling solutions.

 

About the author: Allan Blanchard leads Ambipar Response’s technical consulting group in the US. He and his team of Geologists, Engineers, Environmental Scientists and Technicians specialize in UST removal and rehabilitation of properties contaminated with petroleum and other hazardous chemicals.

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