On October 6, 2005, around 15:05CDT (20:05 UTC), a trailer being pulled by a forklift caught on a valve in the propylene piping system near the Olefins II Unit, pulling the valve and part of the piping loose, leaving a 1.9 inch (3.5 cm) hole. Pressurized liquid propylene poured out of the opening, partially vaporizing, leaving a pool of liquid propylene and creating a flammable vapor cloud. The forklift driver and other nearby contractors saw the cloud and immediately evacuated the area.