_PERMIT FILE - C1981008A ‎(10)‎

• Permit No: C1981008A
• IBM Index Class Name: PERMIT FILE
• Doc Name: Swell Factor Study
• Section_Exhibit Name: Tab 20 Attachment 20-A
• Media Type: D
• Archive: Yes

The swell factor is calculated by relating the amount of fill material to the amount of
cut material. This factor is a percentage increase from the cut material. Prior to
determining the factor, the amount of coal material removed from the pit was subtracted
from the cut material volume as this cut volume represents the amount of overburden,
parting, and coal. Based upon the average tons per acre foot of 1504.378, the conversion
factor to obtain cubic yards of coal is 0.932466 tons per cubic yard and amounts to 20,656
cubic yards of coal.
Results and Discussion
The swell factor is determined by dividing the total amount of noncoal fill material by
the total amount of noncoal cut material, subtracting the unit one and then multiplying by
100. Therefore, the swell factor is 14.99 percent. Considering that mining operations
are performed by scrapers and dozers, this factor is reasonable.
The designed postmining topography landform presented in the November permit revision was
based on an estimated swell factor of 15 percent. As determined from this study, that
swell factor was indeed reasonable and the postmining topography derived from that swell
factor also reasonable.