What systems are used to contain transformer oil spills?

Common containment systems include bunded pits, concrete basins, berms, oil water separators, drain valves with normally closed configuration, absorbent media, and lined secondary containment around the transformer footprint. Substations may use gravel filled pits with impermeable liners and collection sumps to keep oil from reaching soil or waterways. Design typically accounts for full oil volume plus firefighting water, and includes controlled drainage and inspection access. Containment is crucial for compliance and rapid emergency response.