What are subsurface impounds primarily designed for?

Subsurface impounds are primarily designed for the underground collection of liquid waste. This design allows for the containment of wastewater and other liquids in below-ground facilities, which can be particularly beneficial in managing hazardous waste and preventing surface runoff or contamination of surrounding areas.

Such systems offer a controlled environment for managing waste and can help mitigate environmental risks associated with surface storage methods. This underground approach also minimizes exposure to the elements, reducing the chance of evaporation or contamination from external factors.

The other options represent different functions of waste management that do not align with the primary purpose of subsurface impounds. For instance, while solid waste storage is a separate function, and recycling pertains to processing waste for reuse, neither aligns with the core design intent of subsurface impounds as devices for liquid waste containment. Aeration of hazardous materials is also not a function of subsurface impounds, which focus on holding rather than processing or treating waste.