What is typically done to achieve optimal conditions for density in natural soil liners?

To achieve optimal conditions for density in natural soil liners, adding water and compacting the soil is the most effective method. Moisture content plays a crucial role in the compaction process. When water is added to the soil, it helps to lubricate the soil particles, allowing them to slide past each other more easily. This leads to greater compaction as the soil particles are pushed closer together, resulting in a denser and more stable liner.

Compacting the soil while it is at the right moisture content also ensures minimal air pockets, which can weaken the integrity of the liner. Achieving the appropriate density is vital in landfill operations to ensure effective containment of waste and to minimize leachate production.

Other methods, while they may have their uses in different contexts, do not directly contribute to the optimal density conditions as effectively as the proper addition of water and mechanical compaction.