Watson Millican was contacted the same day as the incident and arrived at the plant the next morning. We were tasked to document the scene, conduct interviews, examine evidence, collect the available plant history data, and coordinate efforts with a visual recording consultant retained to record the incident scene.  We traced the plant piping, equipment lineups, and valve positions to confirm the reported operation at the time of the incident and examined the fire damaged items to prepare an initial assessment of the most likely scenarios. While several plausible scenarios were developed, the available evidence supported a scenario that high vapor pressure natural gas liquids (NGLs) were inadvertently routed along with the lower vapor pressure natural gasoline into the atmospheric storage tanks during the plant startup. The NGLs began to vaporize in the storage tank resulting in a vapor cloud which exited the atmospheric tank top vents and settled towards the ground, eventually reaching an ignition source, resulting in the fire involving the tanks.