Bulk Density of Loose-Dumped Mine Spoils for Forestry Reclamation In West Virginia.

The Forestry Reclamation Approach for reclaiming surface mined lands in Appalachia recommends that mine soil materials be placed on the surface with little grading to avoid compaction and to maintain an open and loose material for tree root expansion.  In order to determine the level of compaction of these rocky materials, bulk density measurements are needed.  Mine soils made from blasted rock materials on surface mines in this region are composed primarily of broken rocks and coarse-textured materials with little fine earth material.  Traditional methods like soil cores for measuring bulk density are difficult or impossible and prone to errors in rocky materials.  We used four methods for measuring bulk density in rocky soils on compacted and uncompacted mine soil materials and compared these values to native forest soil bulk density. Sand cone bulk density was significantly lower than bulk density determined by the other three techniques (frame, polyurethane foam, and radiation methods).  These latter techniques all produced similar results.  For substrates, the native forest soil showed an average bulk density across techniques of 1.05 g cm^-3, while the compacted and uncompacted mine soils ranged from 1.70 to 1.84 g cm^-3.  Field efficiency (or the amount of time required to conduct the bulk density determination) was also determined.  The radiation method was most efficient at 345 seconds, compared to 612 seconds for polyurethane foam, 837 seconds for sand cone, and 1605 seconds for the frame.