Earthwork
Swell
The increase in volume that occurs when soil or rock is excavated from its natural state, due to the introduction of air voids.
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In the Field
Swell is critical for trucking and spoil calculations. A yard of in-place clay may become 1.25–1.40 yards when excavated — you need more trucks than the in-place volume suggests. Rock swell can exceed 50%.
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Rule of Thumb
Common swell factors: clay soils 20–30%, sandy soils 10–15%, rock 30–50%. Always verify with geotechnical data for your specific site.