What is the recommended maximum compacted thickness of leaching bed fill per pass when using a tracked bulldozer?

What is the recommended maximum compacted thickness of leaching bed fill per pass when using a tracked bulldozer?

• A. 5 cm
• B. 25 cm
• C. 60 cm
• D. 80 cm

Answer: (B)

The key idea is balancing compaction with surface porosity. Leaching bed fill must stay permeable enough for effluent to infiltrate, so you don’t want to crush the fill into a dense, nearly impermeable layer. When you compact with heavy equipment, you do it in layers to control density and preserve pore spaces. For a tracked bulldozer, keeping the per-pass thickness to about 25 cm (roughly 10 inches) is the practical limit. This depth lets the implement compact the material effectively without overdoing it, which would reduce infiltration and risk creating a hard crust or dense zones that slow or block drainage. Thicker passes (like 60 cm or 80 cm) would overcompact underlying layers and impair permeability, while far thinner passes (like 5 cm) would be inefficient and still carry the risk of uneven compaction if not done carefully. So about 25 cm per pass is the best balance.

The key idea is balancing compaction with surface porosity. Leaching bed fill must stay permeable enough for effluent to infiltrate, so you don’t want to crush the fill into a dense, nearly impermeable layer. When you compact with heavy equipment, you do it in layers to control density and preserve pore spaces. For a tracked bulldozer, keeping the per-pass thickness to about 25 cm (roughly 10 inches) is the practical limit. This depth lets the implement compact the material effectively without overdoing it, which would reduce infiltration and risk creating a hard crust or dense zones that slow or block drainage. Thicker passes (like 60 cm or 80 cm) would overcompact underlying layers and impair permeability, while far thinner passes (like 5 cm) would be inefficient and still carry the risk of uneven compaction if not done carefully. So about 25 cm per pass is the best balance.