Which scenario constitutes a change in service for a UST?

• A. Using a tank to store a regulated substance after previously storing a non-regulated substance.
• B. Moving the tank to a different site.
• C. Replacing the tank with a newer model.
• D. Placing a UST out of service by using it to store a non-regulated substance instead of a regulated substance.

Answer: (D)

A change in service happens when a UST’s use shifts in a way that changes how it’s regulated—the substance stored affects the controls and status of the tank. In the scenario described, placing the UST out of service by using it to store a non-regulated substance instead of a regulated substance clearly alters its service status. Switching to non-regulated storage changes which regulatory requirements apply (and may lead to decommissioning steps), so it’s a change in service.

Relocating the tank, upgrading to a newer model, or merely switching to a different substance without changing the tank’s regulatory status don’t reflect this same service-status shift in context, so they aren’t the same kind of change in service.