What is the maximum size of material allowed in fills?

The maximum size of material allowed in fills is determined by construction standards and regulations to ensure the stability and integrity of the fill material. The correct choice of 12 inches aligns with common industry practices that specify the largest stone size that can be used in fill applications. This size helps to minimize voids and ensures that the fill material can be compacted adequately, which is critical for providing the necessary support for structures built on or near the fill.

Using material larger than this size, such as 18 inches or 24 inches, can lead to issues with compaction, proper load distribution, and could increase the risk of settling or shifting. Smaller sizes, like 6 inches, may also be acceptable but are not the maximum limit. The choice of 12 inches strikes a balance between practicality and the requirements for effective fill material.