Quantities
Excavation & loose spoil
- where
- in-situ (bank) volume (m³)
- length (m)
- width (m)
- depth (m)
- loose volume (m³)
- bulking factor
Explain this equation
This gives the volume of soil dug out and how much space it will take up once loosened. Use it for planning skips, muck-away or stockpile space.
L, W and D are the length, width and depth of the excavation in metres. V_in situ is the volume of undisturbed ground. k is the bulking factor: how many times larger the soil becomes once dug. V_loose is the loose volume.
Dug soil takes up more room than in the ground because air fills the gaps between broken lumps. The bulking factor multiplies the in-situ volume to allow for that.
A 10 m trench 600 mm wide and 1 m deep is 6 m³ in the ground. With a factor of 1.3 that becomes 7.8 m³ of loose spoil.
Watch out: the factor depends on the soil. Skips are often limited by weight, not just volume.
Apply an estimated bulking factor to in-situ excavation.
Enter your values to see the result.
Good to know
Use a soil-specific factor. Loose volume does not establish skip payload; check mass and waste rules separately.
Sources
- Geometry / arithmetic
Estimates are not design approval or British Standards compliance checks. Structural arch, retaining-wall, wind, foundation, lintel and masonry-capacity design are not performed. Use the project engineer’s specification.