Secondary containment

The primary container, such as a drum or tank, is the first barrier. If it leaks, overflows or is knocked over, the second barrier stops the liquid from reaching floors, drains, soil or neighboring containers. This limits harm to people and the environment and makes cleanup easier.

Containment should be sized for the hazard. Many guides suggest it should hold at least the volume of the largest container, plus an allowance, but required capacity depends on local rules and the materials stored, so check your regulations. The material of the tray also matters. It must resist the chemical it holds, as an unsuitable plastic or steel can be attacked by corrosives or solvents.

Secondary containment also supports Chemical segregation. Incompatible chemicals stored together can react if they mix, so separate trays prevent leaks of an acid from meeting a base or an oxidizer from reaching a fuel. SDS Section 7 gives storage advice, and Section 10 lists incompatibilities.

Containment needs maintenance. Rainwater or liquid should be removed promptly, and outdoor bunds may need covers or drains controlled by valves that stay closed. Inspect for cracks and corrosion, and keep a Spill kit close by. Large bulk storage such as an IBC tote or a tank farm often has regulatory requirements.