In earthwork, what is a lift?

• A. 3 inches of compacted depth at full width.
• B. 6 inches of compacted depth at full width.
• C. 12 inches of compacted depth at half width.
• D. 8 inches of compacted depth at full width.

Answer: (B)

A lift is the layer of material placed and compacted in a single operation to a specific compacted thickness. For most earthwork jobs, the standard lift thickness across the full width of the area is six inches. This depth is chosen because it allows the compaction equipment to achieve the required density uniformly without over-stressing the material or creating voids. It also helps prevent segregation and uneven settlement.

If you tried to use a much thinner lift, like three inches, you’d waste effort and time because you’d need more lifts to reach the same depth. A thicker lift, such as eight or twelve inches, is harder to compact to the target density across the full width and height, which can lead to poor density and uneven surface. The wording about full width vs half width matters because full width means the entire placement spans the project width in that lift, whereas half width would complicate achieving uniform compaction across the surface.