Secondary Containment

Secondary containment is your backup when the tank or drum fails. It's the wall around the fuel tank, the bermed area under the drums, the double wall on a tank, the pan under the generator. The idea is dead simple: if the container leaks, the containment holds it so it never reaches the ground or water.

How Big It Has To Be

Under SPCC, bulk oil storage containment has to hold the entire capacity of the largest single container in that area, plus enough freeboard to catch rainfall. So a containment area around three 500-gallon tanks is sized for the biggest one plus rain, not the total of all three. Mobile refuelers have their own rules.

The point for you: don't add a bigger tank or an extra drum to a containment area without checking that the containment still holds the largest container.

Common Types You'll See

Bermed or diked areas around tank farms and drum storage.
Double-wall tanks that contain a leak in the outer shell.
Spill pallets and drum decks with a built-in sump.
Drip pans and containment berms under equipment and generators.

Keep It Working

Containment only works if it's empty and intact. Drain accumulated rainwater properly, and only after you've checked it for sheen. If there's an oily sheen on the water, it's not clean rain and it can't just be released. Watch for cracks, gaps, and corroded valves. And never leave a containment drain valve open, because an open valve turns your containment into a funnel straight to the ground.

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