Mark J. Farrow, P.E.

Development of large sites require civil engineering studies to determine appropriate finished floor elevations and final grade elevations that will result in a balanced cut/fill condition. During these studies, estimates must be made to approximate the shrinkage factor that may be anticipated during excavation and compaction operations. If appropriate shrinkage factors are not used, major changes in grading plans and finished floor elevations are required during construction activities. These changes can result in significant additional change order costs to the owner or developer. Increased development costs can be fairly large if adequate quantities of fill soil are not available to achieve the final pad elevations specified. Problems also tend to escalate if the fill shortage is not detected during the early stages of grading operations. In order to prevent the need for major grading changes during construction, variables affecting shrinkage factors must be identified and considered.
Due to repeated problems with large unbalanced cut/fill quantities at large residential sites across the DFW Metroplex, studies were performed to determine a procedure and design methodology related to the estimation of shrinkage factors used during earthwork operations. This paper presents variables other than compaction levels and in-situ soil densities that can affect the accuracy of balanced cut/fill studies. It also presents a method of calculating the anticipated shrinkage or swell factor based on simple geotechnical parameters.