According to the ERG Table of Isolation Distances, a large spill is defined as a quantity greater than how many gallons?

• A. 55 gallons
• B. 100 gallons
• C. 10 gallons
• D. 5 gallons

Answer: (A)

The key idea here is how the ERG uses a volume cutoff to decide how big a spill is and, therefore, how far to isolate and what actions to take. In the Table of Isolation Distances, the amount that marks the boundary between a small and a large spill is 55 gallons. This means any spill greater than 55 gallons is treated as large, triggering larger isolation distances and more protective actions.

For example, a spill of 60 gallons would be considered large, leading to expanded exclusion zones and more conservative response steps. A spill of 50 gallons would not be classified as large, so the isolation distances would be smaller. The number 55 gallons is simply the boundary used to make that quick distinction in the field.