Abstract: Liquefied gas is stored in a large rigid or semirigid cylindrical container. Between the walls and floor of this container and the walls and floor of an outer container, which may be an earthen cavity in which the container rests, is distributed a continuous layer of insulating material such as perlite or vermiculite in granular form. This insulating material serves as the sole means of support for the rigid or semirigid container and the liquefied gas stored therein. An impediment is included in the construction near the intersection of the floor and side wall of the rigid or semirigid container, the impediment completely encircling the container to substantially limit the cross-sectional area through which the granular insulation material may flow upward. By confining this cross-sectional area, the creep or migration of insulation material from beneath the container during initial filling, repeated filling and emptying of the liquefied gas contents of said container is substantially reduced or eliminated.