Containment and control of oil leaks and spills at electric supply substations is a concern for electric utilities. The environmental impact of oil spills and their cleanup is governed by regulatory authorities necessitating increased attention in substations to the need for secondary oil containment and a Spill Prevention Control and Countermeasure plan. A number of electrical apparatus installed in substations are filled with oil that provides the necessary insulation characteristics and assures their required performance. Power transformers, oil-filled reactors, large regulators, and circuit breakers are the greatest potential source of major oil spills in substations, since they typically contain the largest quantity of oil. Substation pumping facilities and cable terminations that maintain oil pressure in pipe-type cable installations are another source of oil spills. Soil underlying power facilities usually consists of a non-homogeneous mass that varies in composition, porosity, and physical properties with depth.