Washington State Underground Storage Tank (UST) Site Assessment Certification Practice Test

The appropriate height for venting an underground storage tank is based on preventing the accumulation of harmful vapors and ensuring that the vent discharge is above possible sources of ignition, as well as maintaining regulatory compliance. Venting at 12 feet above grade is generally considered sufficient to achieve these objectives.

This height minimizes the risk of vapor migration close to the ground level and provides adequate dispersion of vapors into the atmosphere, allowing for effective ventilation. By ensuring that vents are placed at this height, the potential for hazardous situations is significantly reduced, which is a key component of safety regulations for USTs. Vents positioned at 10 feet may not be high enough to effectively disperse vapors, while those at heights like 15 or 20 feet, although safe, may not offer additional safety advantages and could be impractical or more costly to install. Therefore, 12 feet is regarded as the optimal height for tank venting under standard conditions.