Project specifications require a relative compaction of 95% (modified Proctor).  Construction of a highway embankment requires 10,000-yd³ of fill.  The borrow soil has an in-situ dry density of 94-PCF and a laboratory maximum dry density of 122.5-PCF.  The total volume of soil that must be excavated from the borrow area is most nearly:

Solution: The most common method of assessing the quality of field compaction is to calculate the Relative Compaction (RC) of the fill, defined as:

RC = 100 * (field dry density, PCF) / Laboratory maximum dry density (PCF)

Apply the equation using the given data:   

RC = 100 x 94-PCF / 122.5-PCF = 76.73%

Calculate the required volume of soil that must be excavated from the borrow area:  

(Required Fill) x (Compaction %) x (Relative Compaction)-1 = Excavated   Volume (borrow)

 10,000-yd³ of fill x (95%) x (76.73%)-1 = 12,380-yd³