Secondary Containment means any temporary and/or emergency holding of a product or substance that has been previously retained within a primary system.
The secondary containment system par excellence is the waterproofing of spillage lagoons built around large tanks of the oil industry. This is achieved with a safety system that prevents, in case of emergency, the surface runoff of a highly polluted liquid, and contaminate a large area or even reached the ground-water level, causing an environmental disaster.
A secondary containment system, by definition, should never run but if it does, it should operate for a very short time interval, hours, days ... Therefore, extreme durability is not essential for waterproofing against contact with the retained substance, which would put up the price of the waterproofing without economic compensation at all.