An owner/operator must leave vent lines open and functioning if a UST remains in temporary closure for how many months or more?

The correct duration for leaving vent lines open and functioning when a UST (Underground Storage Tank) is in temporary closure is three months. This requirement is important because vent lines are crucial for maintaining the proper pressure and preventing the buildup of vapors within the tank. If a UST is closed for an extended period, those vapors could become hazardous or lead to compliance issues, making it essential to keep the vent lines operational during the temporary closure.

After three months, the regulations mandate that appropriate safety measures remain in place to mitigate any risks associated with the storage of fuels or other hazardous materials, ensuring environmental safety and compliance with regulatory standards. This three-month rule helps ensure that the integrity of the UST system is preserved, reducing the likelihood of harmful leaks or other issues that could arise from prolonged inactivity.