What is the formula to determine the load factor when accounting for soil swell?

The load factor when accounting for soil swell is represented by the correct formula: bank volume divided by the sum of back volume and the swell percentage.

This formula is critical because it illustrates the relationship between the volume of soil in its undisturbed state (bank volume) and the amount of volume that will actually be present after that soil has been excavated and allowed to swell. Soil often expands or "swells" when it is removed from the ground due to changes in moisture content and structure. Therefore, to accurately calculate the effective volume of the material post-excavation, you must account for this swell.

In practical terms, if you only use bank volume without adding the swell percentage, you would underestimate the volume of soil you have to work with after it has been disturbed. Conversely, using back volume without considering the swell wouldn't account for the soil’s behavior under different conditions. Hence, combining both the back volume and the swell percentage gives a comprehensive calculation needed for accurate construction and excavation assessments, ensuring that project planning and execution remain effective and efficient.