A secondary enclosure, typically consisting of a wall or berm, which surrounds a tank or fluid-handling mechanism, intended to contain any spills or leaks.
The most important of these [secondary containment] provisions are bunds, which are enclosures capable of holding liquids that may escape from the vessels and pipes within the bund wall. — Second progress report on the Buncefield investigation https//web.archive.org/web/20060414122438/http://www.buncefieldinvestigation.gov.uk/reports/report2.pdf
A perennial ("wet") or seasonal ("dry") pond constructed in a depression and in which fish are stored, typically for breeding.
To provide berms or other secondary enclosures to guard against accidental fluid spills within.
Plant room floors are generally bunded and/or waterproofed to contain any leaks or spillages of liquids and fluids from faulty tanks, plant or pipe work. RIW Ltd. Waterproofing Products