Final Grading with Natural Regrade™
Geomorphic reclamation is becoming recognized by industry and regulators as a superior method for mine site reclamation compared to traditional, constant slope reclamation with cross slope ditching, terraces, rock erosion control structures, and trapezoidal channels. However, implementation of this approach both in design and construction is challenging. BRS was retained in 2007 by the AML division of the WDEQ to test Natural Regrade™ software as a tool within an Autocad™ platform to facilitate geomorphic reclamation at a surface mine site in Gas Hills, Wyoming.
Key aspects of the design surface include slopes which transition from convex to concave profiles, concave drainage profiles, a high degree of dissection of the surface by multiple small drainage basins, and meandering channel alignments to increase length with a corresponding decrease in overall gradient. As a result, the intent of the design is to decrease overall runoff flow quantities and velocities at any given point on the final surface, in order to minimize erosional damage to the surface.
Successful application of Natural Regrade™ software in the design process requires an intimate understand of engineering and hydrologic parameters for each individual specific site. This application does not replace sound earthwork design but rather refines and enhances the design. One challenge in the design process is to develop a design that can be implemented and to convey the construction parameters and requirements to perspective contractors.
Properly done, geomorphic reclamation produces aesthetically pleasing, stable final surfaces which encourage vegetative diversity, improved habitat, and decreased maintenance. Translation of a complex geomorphic design to the field requires real-time survey grade GPS control integrated with GPS machine control.