Conceptual Model for Hydrology-Based Geomorphic Evapotranspiration Covers for Reclamation of Mine Land

Abstract

Currently, there are about half a million abandoned mine sites in the U.S. and an estimated 15,000 in New Mexico alone. Surface mining imposes severe ecological effects on the land because it not only alters the vegetation, soils, bedrock, and landforms, but also changes the surface hydrology, groundwater, and flow paths that ultimately result in degraded ecology and water quality. Two relatively new methodologies, fluvial geomorphic landform design and evapotranspiration (ET) waste covers, offer solutions to reclaim these sites for long-term, maintenance-free reclamation. GeoFluv TM is a specific geomorphic grading design method that uses natural analogues for post-mining landscapes and uses design input values taken from stable natural landscapes to make a reclamation design that provides hydrological function, supports ecosystem integrity, and is cost-effective, sustainable, and more visually attractive. It has documented ability to produce surface runoff water quality at least equal to adjacent undisturbed lands and has been used for disturbed lands, including active and abandoned mine sites. Surface ET covers have been used to manage the subsurface hydrology above landfills, waste sites, and mine lands. ET covers protect the underlying materials against erosion, provide a medium for vegetation growth, store precipitation within the cover, and release the stored water into atmosphere so that the infiltration of precipitation is minimized. A conceptual design study is carried out based on an actual, typical abandoned mine site near Raton, New Mexico, to which common problem conditions at abandoned mine sites are assumed. The purpose of this study is to present the concept that covers can be designed by integrating two remediation technologies (geomorphic grading and ET cover) as a geomorphic ET (GET) cover to improve performance. The overall shape of the GET cover can mimic the natural topography of the surrounding area, while the thickness and layering of the cover can be optimized for best vegetation growth and infiltration control. The application of GET cover technology on mine land is expected to substantially improve the reclamation effects by coupling the benefits of the geomorphic cover (drainage reduction, runoff management, vegetation diversity) with the benefits of ET covers (vegetation growth and sustainability, percolation reduction, protection of surface and groundwater). Additional