Abstract: A containment assembly for storing a liquid substance above a ground support surface has an inner tank for receiving and storing the liquid and an outer tank surrounding the inner tank and forming a first air space therebetween for trapping any of the liquid which might escape said inner tank. A support beneath the outer tank provides a second air space between the outer tank and the ground support surface, and a thermal insulating layer substantially envelopes the inner tank, outer tank and support from the ambient. A vapour exhaust vent is provided atop the inner tank, which may include a liquid scrubber for recovering liquids from discharging gases and returning the liquids to the inner tank or elsewhere. Piping is provided for liquid communication between the inner tank and external liquid sources for filling and emptying the inner tank.