In Part I of this series we reviewed the 5 scenarios that require an owner to remove/replace an Underground storage tank (UST). Now we further examine the question: “When should a UST be removed or replaced?”
I’ve worked with gas stations and UST’s since 2002 and I wanted to know the answer to this question. I looked up all the resources I could find to get the answer. I’m sharing my research and conclusions with you. Tell me what I missed and what do you think?
There are articles online that discuss when USTs should be replaced. Some of these articles did not include the variables (age, volume, product stored, design, materials of construction, etc.) that influence the lifespan of a UST. These variables are what make the answer to most UST related questions begin with, “It depends”. This clarifying response might as well be the UST mantra. It’s how most of my answers to UST related questions begin.
Owner Options for replacing UST’s
There are two general approaches to equipment lifecycles. “Preemptive”, or planning for an expected end of the equipment’s functional life cycle, or “Reactive”, making decisions after the equipment has failed.
I want to replace a UST before it leaks and try to avoid any potential bad publicity, NOV’s or cleanup costs. Should I be proactive and remove a UST at an arbitrarily chosen age or date or squeeze every penny out of the UST by utilizing it until it no longer functions as designed. What does the data tell me?
Brief Summary of UST’s in the US
In 1988 EPA set minimum standards for new USTs and required owners of existing USTs to upgrade, replace, or close them. Most of these regulations didn’t take effect until 1998.
In July 2015 EPA revised the 1988 federal underground storage tank (UST) regulations and required all new UST systems installed after April 11, 2016, to use secondarily contained USTs and piping and use continuous interstitial monitoring for release detection. All owners must prove their UST is compatible with regulated substances containing greater than 10 percent ethanol or greater than 20 percent biodiesel. Generally, double-walled USTs since 1995 are compatible with most ethanol-blended fuels and biodiesel fuels.
In September 2019 there were 546,192 active USTs at approximately 197,000 facilities.
Risk assessment tools for a UST
The Cherokee Nation and Region 6 EPA created the Cumulative Risk for Underground Storage USTs (CRUST) Tool, now used in New Mexico as the GoNM tool. This software evaluated the risk of a release from UST systems by grading UST system equipment and analyzing ESRI GIS data sets. The equipment criteria included manufacturer, age, materials of construction, design (Double Wall vs Single Wall), the volume of USTs, number of dispensers, compliance history, and more.
Equipment over 30 years old received the highest risk grade under the age category. Yet, a site with UST’s over 30 years old may still be “Low Risk” after all the risk criteria are calculated.
Industry professionals and regulators have tried to answer “What is the lifespan of a UST?”
From the Association of State and Territorial Solid Waste Management Officials (ASTSWMO) on the aging UST universe:
In October 2015, the ASTSWMO USTs Subcommittee released a report titled, “An Analysis of UST System Infrastructure in Select States”. The conclusion was not definitive:
The average age of in-use USTs has not been calculated by most States, making it impossible to discern trends over time. While the age of a UST does not appear to be a major concern in most states, a few have implemented policy decisions to compel the removal of USTs after they reach a certain age.
Appendix D from the ASTSWMO report provides some interesting quotes. “Arbitrary age limits are a bad idea. We have not seen an age [at which] USTs are likely to fail…Data indicates fiberglass USTs should last over 100 years…Steel USTs may have a similar lifespan, although anodes need to be replaced periodically…USTs [should be replaced] not because of their age, but because of the fuels to which they are exposed. If fiberglass USTs [contain] diesel there is no need to replace them. If they are going to see 15% or greater alcohol, they should be removed or replaced…”
“Requiring replacement of USTs at the end of their warranty period is a crazy idea. Many components of UST systems have warranties of only 1 year or a few years…Owners are not required to replace those components at the end of a warranty period. Would you require cars to be replaced at the end of their warranties?”
Some State Regulators and individuals in the industry have implied, “A UST is no longer useful after its warranty has expired”. Fiberglass USTs are warrantied for 30 years and steel USTs are warrantied for 10. So steel USTs are only good for 10 years? Is an expired warranty a finite declaration that the equipment won’t function after that? Is a car that is warrantied for 150,000 miles, junk after reaching that milestone?
The Petroleum Equipment Institute on the aging UST universe
On September 19, 2018, PEI Tulsa letter, PEI suggests working together to determine the lifecycle of a UST system by compiling and aggregating data on UST systems, to evaluate the risks associated with older USTs and encourage strategies for reducing those risks. Collaboration, data input and feedback from EPA, Tribal and State regulators, ASTSWMO and NWGLDE workgroups, online UST compliance groups, Petroleum Equipment Institute members, Petroleum service technicians, Technicians in the petroleum Industry, Owners/operators of UST systems, NEIWPCC, NFPA, API, Underwriters Laboratories (UL) and all Industries associated with UST’s, might reveal the true lifecycle of a UST.
To get a realistic idea on the life cycle of a UST requires standardized data collected from all USTs and reported in a universal format. Without the data to assess the trends, very little can be reliably concluded.
How often do UST’s fail?
The Fiberglass UST & Pipe Institute on SW Fiberglass UST failures:
A 2013 report from the Fiberglass UST & Pipe Institute titled “Fiberglass Underground Storage UST Success in the USA” claims that of 19,240 SW fiberglass USTs, with an average age of 8 years, only 4 had failures and 3 of those failures were attributed to poor installation practices.
UST’s since 2016
By federal regulations, every new UST system (Since April 11, 2016) must have secondary containment, including double-walled USTs and piping. Looking 10-30 years in the future at these new UST systems, (with continuous interstitial leak detection, tested and maintained annually) is the owner going to be required to remove the UST from service because it is out of warranty? Or when someday of the year arrives?
Conclusion: When should an underground storage UST (UST) be removed or replaced?
The irony of this entire article is that most recorded releases from a UST system did not originate from the UST. So we just spent all this time examining how long a UST will last when a release probably will not come from the UST. ASTSWMO reports “The few published studies available on this subject all have concluded that components other than the UST itself – i.e., piping, joints, connectors, gaskets, dispensers, etc. – are the source of most leaks”.
As we noted in part I, there are 5 reasons a UST has to be removed/replaced. But, can an owner of a UST plan for when to remove or replace a UST? Until we have reliable data and apply valid scientific analysis, the only concrete answer to when a UST should be removed/replaced is the 5 reasons in part I.
That may not be a very satisfactory answer. My personal opinion for different scenarios is below.
If a UST was installed before 1988 and it is a single-walled UST, it should be replaced.
If the UST’s were installed between 1988 and April 11, 2016, the UST is double-walled with continuous interstitial monitoring, compatible with the product stored, and the equipment is being inspected and maintained annually? I wouldn’t worry about the UST until it fails a release detection test. Any other UST system, it depends. Who made it, what is it made it out of, what is the release detection method, how has the compliance history been with this site, etc..?
If the UST’s were installed after April 11, 2016, these USTs will last more than 50 years. The UST has to be compatible with the product stored, it is double-walled with continuous interstitial monitoring, and the equipment is being inspected and maintained annually, I wouldn’t worry about the UST until it fails a release detection test or a new fuel additive (Lead, MTBE, ethanol, ??) is introduced that causes the materials new USTs are created from to degrade.
Thank you for reading these. Let’s hear from you now. What other gas station issues do you want to hear about? What about the other components of the UST system? What did I miss? What does your experience say?
About the Guest Author:
This article was originally posted on LinkedIn by Robert Largent, CHMM , an Environmental Engineer @ AAFES (The Exchange).
Robert Largent is experienced in most environmental media and an active member of the gas station and UST communities. His introduction to UST systems in 2002 has led to an extensive career in UST gas station compliance. This includes 12 years of assisting the Cherokee Nation and several Intertribal organizations. He has provided compliance assistance, training, regulatory guidance, installation, removals, remediations and every aspect of building, operating, and decommissioning gas stations. He has earned multiple certifications/licenses related to gas stations including NACE CP tester, CHMM, Sanitarian, as well as Installations, Removals, and Remediation certifications. He has also presented at industry events on UST topics including operator training, installations, removals, remediation, inspections, cathodic protection, and vapor recovery. As an active contributing member of the industry, he also participated in drafting and commenting on parts of the 2005 Energy Policy Act pertaining to UST’s and the 2015 40 CFR 280 update as well as several state UST regulatory updates.