What is a disposal field in subsurface sewage disposal systems?

A disposal field, also known as a drain field or leach field, is an essential component of subsurface sewage disposal systems. It serves a crucial function by utilizing the natural properties of the soil to absorb and treat effluent that comes from the septic tank. Once the sewage is processed in the tank, the liquid effluent is transferred to the disposal field, where it percolates through the soil layers.

The soil acts as a natural filter, removing contaminants and pathogens from the effluent as it moves downward. This process helps to purify the wastewater before it eventually reaches the groundwater. The effectiveness of a disposal field hinges on various factors, including soil type, depth to groundwater, and moisture levels, all of which influence how well the effluent is treated.

In contrast, storing solid waste, holding sewage in a tank, or chemically treating sewage are not functions of the disposal field. Instead, these are associated with different parts of the sewage treatment process. The disposal field specifically focuses on the absorption and natural treatment of liquid waste, aligning it with the definition provided in the correct answer.