What is used to replace material removed from pipeline and culvert trenches?

Backfill is the material specifically used to refill trenches or excavations after pipeline or culvert work has been completed. This process is vital to restore the ground to its original condition and provide support for any structures placed above. Backfill can consist of various materials, such as soil or aggregate, depending on the project requirements and specifications.

The primary purpose of backfill is to ensure proper support and stability around the pipelines or culverts to prevent settling or shifting that could adversely affect their function or integrity. In addition to structural support, backfill also aids in managing surface water drainage and minimizing erosion.

In contrast, base course refers to a layer of material used in pavement construction to distribute loads and provide a stable foundation, while bearing capacity relates to the ability of soil to support loads without failure. The angle of repose is related to the steepest angle at which a sloped surface of loose material will remain stable and does not pertain to the refilling of trenches directly. Therefore, backfill is the most suitable and correct term for material used in this specific context.