Can I change the volume of my tank to avoid increasing containment? - SPCC Plans - Revisited
John K. Carroll III
Associate Managing Director at Witt O'Brien's, LLC, Part of the Ambipar Group
(This article was written without AI tools, i.e., ChatGPT.)
I’ve spent the past three weeks in Africa, so I haven’t had time to prepare any new content. I’m reposting this slightly modified article, as the question continues to arise frequently.
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The Environmental Protection Agency’s (EPA) Spill Prevention, Control, and Countermeasure (SPCC) Plan Guidance for Regional Inspectors does a great job simplifying the answer to the title question (click here to read ). If you still have questions after reading the guidance, email me at the email address noted below.
Typically, we get this question for one of two reasons:? 1) a company resurveys a tank farm and finds the containment numbers had been inaccurately represented, and their containment is short, and/or 2) a company wants to bring an old permanently closed tank back into service, but the tank is larger than the current containment will allow.
We’ve just recently encountered another reason: a company wants to avoid complying with the EPA’s Facility Response Plan (FRP) requirements because the tank putting them into FRP compliance never actually gets completely filled. In this case, it is cost-prohibitive to remove the tank and then replace it with a smaller one, and the company wants to be able to change its status in the future if market conditions change.
To kick off this conversation, here is an example of the type of questions we receive:
"If we have an old tank that has been permanently closed and we want to bring it back into service but our containment is undersized, can we install vents to reduce the tank's volume rather than needing to raise its containment? What if we just set alarms to manage a new controlled volume? Will that work, too?"
The Guidance Document explains this in detail in Chapter 2.7.3, labeled Tank-Rerating.
Shell capacity is used as the measure of storage capacity, unless physical changes are made to the design shell capacity in a permanent, non-reversible, manner that reduces the capacity of the container to contain liquid. An owner or operator may reduce the capacity of a tank by changing the shell dimensions (e.g., by removing shell plate sections, or installing a double bottom in accordance with applicable industry standards). When the alteration is an action such as the installation of a double bottom or new floor to the container, the integral design of the container has changed, and may result in a reduction in shell container capacity.
EPA also considers overflow ports or vents installed in accordance with industry standards as an acceptable method of reducing the shell capacity of container. [To be considered as overflow ports, the size and number of overflow ports shall be based on filling the tank (i.e., fill rate) without increasing the liquid level above the bottom of the overflow port.] These properly engineered alterations can be considered permanent when the alteration to the container is performed in accordance with applicable industry standards. However, even when a shell penetration is completed in accordance with industry standards, this does not re-rate the storage capacity of the tank to a lower capacity if the owner or operator overrides the alteration.
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When an overflow nozzle is equipped with a pipe and a valve, and the valve is then closed, the container’s capacity reverts to the original shell capacity. [A valve is not recommended unless otherwise required by code.] If an overfill opening is closed at a later date, this constitutes a change in service and as such, per API 653, the tank’s suitability for service must be reevaluated and the original capacity of the tank to the top of the shell becomes the measure of storage capacity. This and similar actions that reverse or effectively override the prior alteration used to change the original shell capacity of the container may change the shell capacity again and require an amendment to the SPCC Plan.
Any container alteration will require a technical amendment to the SPCC Plan certified by a PE in accordance with §112.5. The PE will ensure that the alteration was performed in accordance with applicable industry standards and in consideration of original design specifications. Relevant industry standards include American Petroleum Institute (API) Standard 653 “Tank Inspection, Repairs, Alteration, and Reconstruction” (API-653). This standard includes requirements for adding shell penetrations (which may be used to reduce container capacity) such as shell penetration (i.e., nozzle) for overflow. Tank alterations which change the original shell capacity may affect secondary containment capacity necessary to comply with SPCC requirements and FRP applicability and requirements under 40 CFR part 112 subpart D. Thus, changes in container storage capacity may affect FRP requirements for calculating the worst case discharge volume and the amount of resources required to respond to a worst case discharge scenario to comply with the FRP requirements.
Simply drilling a hole in the container, so that the container cannot hold liquid above that point, may not be an appropriate method to re-rate tank capacity when this alteration is not in accordance with applicable industry standards. In this case the original capacity of the container has not changed and remains the measure of storage capacity. Finally, devices (e.g., hydraulic overfill valves and high level alarms) and procedures (e.g., administrative controls) may not be used to limit the capacity of a storage container. For more information on how to evaluate a re-rated tank see Chapter 7: Inspection, Evaluation, and Testing (see Section 7.6.1 ).
The bottom line is yes, you can alter a tank to avoid having to increase secondary containment. However, it is not as simple as drilling a hole in the tank. As such, it’s important to discuss your plans with your ?P.E. before taking action to ensure they are comfortable with your approach – because they will need to sign off on the plans in order to seal the changes in the SPCC Plan (technical amendment ).
The last paragraph from the above guidance document is very important. Simply stating you will not fill the tank beyond x or simply installing an alarm to note when a tank level reaches x does not satisfy the requirements for re-rating a tank’s volume. You must work with your P.E. to ensure that your planned approach conforms with the rule requirements.
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These articles offer additional support for today’s discussion.
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For a complete listing of archived articles and compliance insights, click here . Past articles cover training requirements, clarification on additional unclear elements within the above rules, and much more.
We are here to help solve your compliance questions and challenges. If you need compliance assistance or have a question, please email John K. Carroll III ([email protected] ), Associate Managing Director – Compliance Services, or call +1 954-625-9373.
Witt O’Brien’s:
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