A system and method for storing multiple canisters containing high level waste below grade that afford adequate ventilation of the spent fuel storage cavity. In one aspect, the invention is a system comprising: an air-intake shell forming a substantially vertical air-intake cavity; a plurality of storage shells, each storage shell forming a substantially vertical storage cavity; a hermetically sealed canister for holding high level waste positioned in one or more of the storage cavities so that a gap exists between the storage shell and the canister, the horizontal cross-section of each of the storage cavities accommodating no more than one canister; a removable lid positioned atop each of the storage shells so as to form a lid-to-shell interface, each lid containing an outlet vent forming passageways between an ambient environment and the storage cavity; and a network of pipes forming a passageway between a bottom portion of the intake cavity and a bottom portion of each of the storage cavities.