Excess spoil generated during surface mining in southern West Virginia is generally placed in headwater valleys. Known as valley fills, these structures are designed to move water rapidly through constructed drains to maximize geotechnical stability using the conventional design method termed Approximate Original Contour (AOC). Seepage from valley fills tends to be elevated with respect to calcium, magnesium, alkalinity and sulfates and there is evidence that, in high concentrations, these ions can contribute to stream degradation. New fluvial geomorphic principals are being researched to aid in reclamation alternatives to AOC designs. Geomorphic designs have proven successful in semi-arid regions; however, there has been little research performed into the application of this approach for eastern surface mining reclamation.
Geomorphic reclaimed landforms aim to improve groundwater movement and diminish contaminant transport through increased runoff and reduced groundwater infiltration. The objective of this research was to determine if geomorphic reclamation techniques result in improved selenium concentrations of discharge water as compared to conventional reclamation for valley-fills constructed of blasted rock. Comparisons investigated if groundwater and contaminant desorption could be improved by altering valley-fill construction. Three-dimensional finite-element groundwater modelling was performed on two valley-fill geometries and was coupled with laboratory testing of selenium leaching from blasted-rock overburden. Selenium desorption characteristics and distributions were compared. Lower water volumes and shorter contact times with overburden fill resulted in lower masses of selenium desorbed from geomorphic fills as compared to conventional techniques. When results were normalized by varying fill areas and volumes, the geomorphic valley-fill exhibited 23% lower surface infiltration, 27% lower discharge volumes and 39% lower selenium discharge loads as compared to the conventional reclamation. To achieve these advantages in geomorphic reclamation, infiltration must be reduced through both the construction of curvilinear slopes of the fill surface and the creation of a low infiltration-capacity reclaimed stream.
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