Which of the following is a key component of a mound soil absorption system?

A sand mound is fundamental to a mound soil absorption system because it serves as the primary interface where wastewater is treated before it enters the surrounding soil. The purpose of the sand mound is to provide adequate space for the soil absorption process to occur, while also ensuring that the effluent from the septic system is evenly distributed over a larger area. This system is particularly useful in areas with shallow soil depth, high groundwater tables, or poor drainage conditions, allowing for efficient wastewater management while minimizing the risk of contamination to groundwater.

Other components in typical waste disposal systems, such as concrete slabs, gravel pits, or clay liners, serve different functions or may be used in other types of systems, but they do not fulfill the essential role that a sand mound plays in effectively treating and dispersing wastewater in mound systems.