A 16 inch natural gas pipeline, located in California (USA), which conveys gas entrained with oil containing polychlorinated biphenyl (PCB) was damaged by third party activity.

An excavation subcontractor using a drill punctured the gas pipeline. The hole allowed the gas to escape in an upward direction, which was then carried towards nearby buildings. The gas did not ignite and was naturally dispersed. However, there was a fall out of the PCB-oil as a mist, which contaminated an eight square block area of the city’s financial district. This initiated the evacuation of approximately 30,000 individuals

Image Credit: NTSB