What type of fill tends to separate by particle sizes when dumped down a steep slope into a deep depression?

• A. Granular fill
• B. Backfill material
• C. Common borrow fill
• D. Compacted fill

Answer: (C)

When loose fill with a mix of particle sizes is dumped down a steep slope, it naturally segregates as the flow carries coarse pieces differently from fines. Common borrow fill is typically a poorly graded, variable mix, so it’s most prone to this size separation as it drops into a deep depression. The coarse material tends to move differently and may ride ahead or settle differently than the fines, creating visible segregation and layering.

Granular fill, backfill material, and compacted fill are either more uniform or placed with procedures (such as lifting, moisture control, and compaction) that reduce this tendency. That's why common borrow fill is the best answer here.