What must backfill be free from?

Backfill must be free from debris to ensure proper drainage and stability of the surrounding structures. Debris can include materials such as rocks, construction waste, and other foreign objects that can affect the integrity of the soil and how it compacts. When backfill is not clean, it can lead to uneven settling, increased erosion, or obstruction of drainage pathways, all of which can ultimately compromise the structural integrity of the building.

While it may seem that other options could also be important, water, soil, and air are components that typically have a valid role in the backfilling process. Soil, of course, is the primary material used for backfilling. Water, in controlled amounts, can actually assist with compaction, and air can be present in the soil without causing issues as long as the backfill has the proper composition. Thus, ensuring the backfill is free from debris is critical for maintaining the intended performance of the backfilled area.