A liquid-containment barrier installed underneath an aboveground storage tank that is sufficiently impervious to the liquid being stored. Its purpose is to divert a product release toward the perimeter of the aboveground storage tank where it can be easily detected and to prevent liquid from contaminating the environment.
Release prevention barriers are composed of materials that are compatible with the liquid being stored in the aboveground storage tank and that meet proper engineering standards. Examples include steel, concrete, elastometric liners or other suitable materials that meet the criteria described above.
See also PEI/RP800.