A land disposal unit, or LDU, is a site in which hazardous waste is remedied through natural and man-made processes. "Land disposal" of hazardous waste is defined in the U.S. Resource Conservation and Recovery Act (RCRA).^[1] Types of LDUs for hazardous waste disposal:

• Landfill
• Surface impoundment
• Waste pile
• Land treatment unit
• Injection well
• Salt dome formation
• Salt bed formation
• Mine
• Cave.^[2]