NASCLA Accredited Commercial General ContractorSite WorkMedium
A construction company is planning to install a new utility line across a site. The excavation will involve removing 1,200 cubic yards of undisturbed soil. The soil has a swell factor of 25%. How many cubic yards of soil will need to be hauled away after excavation?
- A1,200 cubic yards
- B900 cubic yards
- C1,800 cubic yards
- D1,500 cubic yards
Show answer & explanationAnswer & explanation
Correct answer: D. 1,500 cubic yards
When soil is excavated, it expands due to the introduction of air voids. A swell factor of 25% means the excavated volume will be 125% of its original undisturbed volume. Therefore, 1,200 cubic yards * (1 + 0.25) = 1,200 * 1.25 = 1,500 cubic yards.
Why the other options are wrong
- A. This assumes no swell, which is incorrect as excavated soil always swells.
- B. This calculates the original volume minus 25%, indicating shrinkage, which is incorrect for excavation.
- C. This would be a 50% swell factor, which is too high for the given scenario. 1200 * 1.50 = 1800.
Soil Swell Factor
The ratio of the volume of excavated (loose) soil to its original undisturbed (bank) volume, typically expressed as a percentage.
- Excavated soil occupies more volume than in its natural state.
- Important for calculating hauling and disposal needs.
- Varies significantly by soil type (e.g., rock swells more than sand).
Memory trick: Dig it Up, It Gets Bigger: Swell Factor is The Key.