Defendant owns and operates a petroleum bulk storage terminal in Guaynabo, PR. The complaint alleges violation of the requirement to use ?good air pollution control practices? found at 40 C.F.R. ? 63.11085 for failure to properly maintain the internal floating roofs in its gasoline storage tanks, resulting in dangerously high concentrations of gasoline vapors accumulating in the internal air space in the tanks, which created a risk of fire and explosion and resulted in air vapor emissions from tank vents. This violation was previously the subject of a CAA section 303 emergency order issued to the Defendant on May 20, 2019. The complaint also alleges violation of requirements to take timely action when liquid was observed on top of the internal floating roof (IFR) in one tank. Finally, the complaint alleges that t he Defendant failed to properly operate its truck loading rack vapor recovery unit (VRU), leading to excess emissions of gasoline vapors, and failed to comply with related monitoring and recordkeeping requirements.