Farmington Mine Disaster

in the link watch the video about a 1968 coal mine disaster which killed 78 miners in West Virginia and and list two possible controls for preventing or
mitigating/reducing the severity of coal mine explosions or, in the alternate video, flooding by applying these controls:

Hazard control by elimination
Hazard control by substitution
Hazard control by engineering controls
Hazard Control by administrative controls including training
Hazard control using personal protective equipment