Design of the Ruby Gulch Repository, Gilt Edge Mine, South Dakota

The recently constructed Ruby Waste Rock Repository utilizes a structured geomembrane with an integral drain layer to form a barrier over a 26 hectare (65-acre) valley fill of waste rock and spent ore from the Gilt Edge Mine in Lawrence County South Dakota. The $20 million capping project is intended to minimize water and air infiltration into a mass of acidic waste rock that was placed in a steep valley fill. The new structured geomembrane product provides excellent frictional and drainage characteristics for this steep-slope application in a moist climate. The recently completed cap experienced an extreme rainfall event and performed well.