Secondary release containment diking

Transfer facilities, processors and rerefiners, and burners must also have secondary containment systems to prevent oil from reaching the environment in the event of a spill or leak. Secondary containment consists of an oil-impervious dike, berm, or retaining wall to contain releases, as well as an oil-impervious floor to prevent migration. 

Secondary containment enclosures other than double-wall construction have been widely used to control vessel leaks. Bunkers built around underground storage tanks are common examples of this approach to preventing releases to the atmosphere and into the soil around the tank, to minimize potential for ground water contamination. Use of tank-high dikes with covers or roofs is another example of secondary containment that limits postrelease emissions. 

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