Abstract: A method and system is disclosed for reversibly establishing a closed, flow-impervious cryogenic barrier about a predetermined volume extending downward from a containment site on the surface of the Earth. An array of barrier boreholes extend downward from spaced apart locations on the periphery of the containment site. A flow of a refrigerant medium is established in the barrier boreholes whereby water in the portions of the Earth adjacent to the barrier boreholes freezes to establish ice columns extending radially about the boreholes. The lateral separations of the boreholes and the radii of the ice columns are selected so that adjacent ice columns overlap. The overlapping ice columns collectively establish a closed, flow-impervious barrier about the predetermined volume underlying the containment site. The system may detect and correct potential breaches due to thermal, geophysical, or chemical invasions.