How should material be dispersed in a fill area to allow for compaction?

Material should be dispersed in a fill area higher than the desired grade to allow for proper compaction. When fill material is initially placed above the target elevation, it accounts for the reduction in volume that occurs during the compaction process. This settling is a result of air being expelled from the material and particles rearranging to create a denser configuration. If the material is placed at or below the desired grade, there may not be enough volume during the compaction to achieve the necessary density, which can lead to issues like settling or uneven surfaces later on. Placing material higher than needed ensures that after compaction, the fill will meet the desired grade and have the appropriate stability and strength for the intended use.