[en] A substantial quantity of low-level radioactive and hazardous wastes has been interred in shallow land burial structures throughout the United States. Many of these structures (trenches, pits, and landfills) have proven to be unstable. Some surface feature manifestations such as large cracks, basins, and cave-ins are caused by voids filling and physico-chemical degradation and solubilization of the buried wastes which could result in the release of contamination. The surface features represent a potential for increased contamination transport to the biosphere via water, air, biologic, and direct pathways. Engineering alternatives for the reduction of buried waste and matrix materials voids are identified and discussed. As a guideline, a reduction of the voids within the waste to 80% or more of maximum relative dry density (a measure of in situ voids within the waste) is proposed. The advantages, disadvantages, and costs of each alternative are evaluated. Falling mass and pile driving engineering alternatives were selected for further development