What requirement was mandated by the 1984 amendment to RCRA for hazardous waste landfills?

The requirement for double liners in hazardous waste landfills was mandated by the 1984 amendment to the Resource Conservation and Recovery Act (RCRA) due to concerns about the environmental risk posed by leaking landfills. The double liner system consists of two layers of impermeable material, often with a leachate collection system in between, designed to prevent any potential leachate—contaminated liquid waste—from escaping into the surrounding soil and groundwater. This engineering control is critical for protecting public health and the environment from the long-term hazards associated with the improper management of hazardous waste.

The other options may reflect practices related to hazardous waste management, but they do not specifically address the legal requirements introduced by the 1984 amendment to RCRA as directly as the double liner system does. Instead, the amendment's primary focus was on ensuring that landfills are designed to minimize the risk of environmental contamination, thereby highlighting the importance of double liners in modern hazardous waste management practices.