What method is NOT an approved method for abandoning an underground tank?

When it comes to abandoning an underground tank, there are established methods that ensure safety and environmental protection. Pulling a vacuum is not an approved method for tank abandonment because it does not adequately secure the tank in a manner that prevents potential leaks or contamination. This process might leave residual vapors or contaminants in the tank, which could pose risks to the surrounding soil and groundwater.

In contrast, excavation allows for the complete removal of the tank and any associated contaminants, while filling with concrete can provide a method to immobilize the tank in place effectively. Disconnection typically involves emptying the tank and securely closing off any connections to prevent leakage. These methods are considered safe and effective in ensuring that abandoned tanks do not pose health or environmental hazards.