A container, intended for use in the disposal of hazardous waste, is provided with pairs of opposed locking rails which are attached to the interior faces of the side walls and project into the container. Extending between each pair of opposed locking rails are pairs of hold-down bars which have resilient arms biased towards one another to engage ratchet bars formed in the locking rails. The ratchet bars allow for downward motion of the hold-down bars, but do not allow for upward motion. Racks are placed between the waste material to be compacted and each pair of hold-down bars to increase the compression maintaining capabilities of the hold-down mechanism. The hold-down bars prevent expansion of the waste material through their engagement with the locking rails. Several pairs of hold-down bars and racks can be used in each container. A lid for the container is designed to be attached tightly to the container with clips which grip openings on the container walls. Optional supports can be connected to the container bottom with detachable clips to enable easy forklift transport.