Abstract: Apparatus for confining a leakage of polychlorinated byphenyl (PCB) from an utdoor electrical substation while permitting rain water to be discharged into the outside environment when no PCB is present. The electrical equipment is disposed on a walled pad having sufficient containment volume to hold the maximum PCB leakage. The outlet from the containment volume is through a water/PCB separator float valve which is disposed vertically in a catch basin. The valve has a tubular body having a flow-through section with apertures which communicate with the catch basin and a converging section of circular cross-section above the flow-through section. A spherical float having a specific gravity between that of water and PCB is confined in the tubular body.