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Entering Swell and Yield Factors

Use swell and yield factors to estimate how much dirt swells when it is excavated from its natural state on a job site, and how much dirt you will need when you compact it on a job site.

ProContractor considers natural dirt in terms of Bank Cubic Yards (BCY) or Bank Cubic Meters (BM3). Once you excavate or remove the dirt from its normal state, it swells and becomes Loose Cubic Yards (LCY) or Loose Cubic Meters (LM3). When you replace and compact the dirt, it becomes Compacted Cubic Yards (CCY) or Compacted Cubic Meters (CM3).

One of the most important concepts to understand is that you must always work with the same units of measurement. One cubic yard that is in the ground of a job site (BCY) will be more than one cubic yard when you excavate it out of the ground (LCY). When you move this dirt to another location on the job site and compact it in the ground (CCY), it will usually be less than a cubic yard.

For example, if you excavate 1.0 BCY of dirt from the ground, it may swell 25%. To determine the volume of dirt you will have to haul to another location on the site or off the site, you would multiply the cubic yard by a Swell Factor, which in this case would be 1.25. This would convert the 1.0 Bank Cubic Yard (BCY) to 1.25 Loose Cubic Yards (LCY).

According to the estimate of the job, you now know you will actually need to haul this 1.25 LCY to another location on the job site to use as compacted fill material. This means that the Loose Cubic Yards will become Compacted Cubic Yards (CCY). To calculate this, you multiply the Loose Cubic Yard value by the Yield Factor. For example, the 1.25 LCY we calculated in the previous example might need to be compacted by 10% when filled into the ground to convert the unit to Compacted Cubic Yards. To calculate this, you would multiply 1.25 LCY by 1.1, which equals 1.38 Loose Cubic Yards to equal one Compacted Cubic Yard.

If you don't know the yield factor for the dirt on a job site, use the yield calculator in ProContractor to determine what the yield factor based on the swell factor, original density, and design density. The basic equation is:

Swell factors range between 0.5 and 4.00, and yield factors can range from 1.00 to 4.00. You can apply swell and yield factors to every layer of the job.

If you don't plan to use swell or yield factors for a job site, set both factors to 1.

To set default swell and yield factors, select the appropriate boring attributes. See Customizing Boring Attributes for more information.

If you change the swell or yield factor for a material, the factor is updated everywhere the material is used.


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