Excavation and muck-away
Muck-away tonnes and lorry loads
- where
- weight to remove (t)
- volume in the ground (m³)
- bank density (t/m³)
- lorry loads
- lorry payload (t)
Explain this equation
This gives the weight of spoil to take off site and how many lorry loads that is by weight, for pricing haulage and tipping.
V is the in-ground volume, ρ is the bank density of the soil in tonnes per cubic metre, T is the total weight and P is what one lorry can legally carry. Nl is the number of loads.
Weight is volume times density. Using the in-ground volume with the in-ground density gives the right answer, because bulking adds air, not weight. The result is rounded up to whole loads.
Sense check: most dug clay and earth is about 1.9–2.1 t/m³, so 10 m³ in the ground is roughly 20 tonnes.
Watch out: do not multiply the bulked volume by the bank density; that overstates the weight by the swell percentage.
Weight of spoil to be carted away, and how many grab-lorry or tipper loads that is by weight.
Enter your values to see the result.
Good to know
Use the in-ground (bank) volume with the bank density; the weight does not change when the soil bulks. Caterpillar bank densities: clay in natural bed 2.02 t/m³, wet earth 2.02, dry packed earth 1.90, damp sand 1.90, pit-run gravel 2.17, topsoil 1.37. HSE notes that a cubic metre of soil can weigh over 1.5 tonnes. Payload depends on the vehicle and its plated weight: ask the haulier what they can legally carry. Tipping is usually charged per tonne or per load and waste must be classified (inert, non-hazardous or hazardous) for landfill.
Common mistake
Working out weight from the bulked volume and the bank density, which double-counts and overstates the tonnage.
Limits
Average densities. Wet weather can add significantly to the weight of clay.
Sources
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow BS 8500, BS EN 206, BS EN 752, Building Regulations Part H, manufacturers’ data and your engineer’s design. Structural concrete and foundations need a competent designer.