What size vent hole should be left in a tank that is decommissioned in place?

In the context of decommissioning an underground storage tank (UST) in place, the correct size for a vent hole is 1/8 inch. This specification is important for several reasons.

Firstly, the vent hole needs to be small enough to prevent any potential contaminants or substances from entering the tank and causing environmental hazards. By using a 1/8 inch hole, you provide a sufficient pathway for any gases that may accumulate inside the tank due to decomposition or chemical reactions, while still minimizing the risk of external contaminants infiltrating the tank environment.

Moreover, the size of the vent hole also plays a crucial role in safety. A larger vent hole could pose risks, such as making it easier for atmospheric pressure changes to disrupt the tank's integrity or allowing for more significant releases of vapor, which can be hazardous if flammable. A smaller vent effectively balances the need for pressure equalization without compromising safety.

Additionally, the regulations governing USTs typically require adherence to specific guidelines for vent hole size to ensure environmental protection and public safety. Following these guidelines, such as leaving a vent hole of 1/8 inch, reflects compliance with best practices in tank decommissioning procedures.