Special Topics in Environmental Management

What Everybody Wants to Know About Secondary Containment

A delivery truck with a 100-gal diesel fuel tank delivers fuel to my facility. Is SPCC applicable to it, particularly the secondary containment requirement, or is it covered under 40 CFR 112, Appendix B, the MOU with DOT and DOI?

As long as the vehicle is in “transportation mode” (it has papers and it’s stopping at your facility for a delivery only and not, for example, overnight), then you are not responsible for the fuel that is powering the vehicle and are most likely exempt from SPCC. But you are responsible for the fuel being transferred to your tank. However, in terms of the tank powering the delivery truck, it is also a good idea to err on the side of caution. When regulators say you are most likely exempt, they are leaving themselves some wiggle room. Obviously, if you see that tank leaking, you should do something about it.


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For the purposes of SPCC, and providing compliance with the secondary containment provisions, is a “double-hulled” or “double-walled” storage tank considered to provide the secondary containment?

Shop-built double-walled or double-hulled aboveground storage tanks (ASTs) may be used for secondary containment purposes, as long as they are operated with certain protective measures. EPA describes these measures as “when the inner tank is an Underwriters’ Laboratory-listed steel tank, the outer wall is constructed in accordance with nationally accepted industry standards (e.g., those codified by the American Petroleum Institute, the Steel Tank Institute, and the American Concrete Institute), the tank has overfill prevention measures that include an overfill alarm and an automatic flow restrictor or flow-shutoff, and all product transfers are constantly monitored.” Shop-fabricated double-walled ASTs may satisfy the secondary containment requirements of 40 CFR 112.7(c) and the bulk secondary containment requirements of 40 CFR 112.8(c)(2).

When using double-walled ASTs as secondary containment, certain inspection requirements apply.

Owners and operators must inspect the inner wall and interstitial spaces of a shop-built double-wall AST, using industry standards such as the SP001-00 Standard for Inspection of In-Service Shop-Fabricated Aboveground Tanks for Storage of Combustible and Flammable Liquids. In addition, any piping, equipment, or device not contained within a double-walled AST is subject to the requirements of 40 CFR 112.8(b)(3) and (4) if such piping, equipment, or device is in an undiked area.

Here’s more on simplifying secondary containment requirements.


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During delivery of fuel to my site, a tanker truck comes up to refuel tanks with gas or diesel. Does our SPCC plan need to address the ability to deal with a spill where the entire truck loses its load or only a portion of the tank load?

As required under 40 CFR 112.7, your facility’s SPCC Plan must address your containment system’s ability to hold at least the maximum capacity of any single compartment of a tank truck loaded or unloaded at your facility. If there are separate areas for different unloading or loading operations, each area should be designed specifically to hold the capacity of the largest carrier anticipated to conduct operations in that area. Loading/unloading areas are typically are designed to permit vehicle access and incorporate a secondary containment system. The most common tanker truck loading/unloading area containment system is a covered, curbed, and graded area that drains to a catchment basin.

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