In 1974, the Climax Molybdenum Co., then a subsidiary of AMAX Minerals Co., closed its Urad Mine near Berthoud Pass in Clear Creek County, CO. The tailings - the waste rock residue remaining after the ore is extracted - provided a poor foundation for plant growth, especially young trees, which could be uprooted in the strong winds that frequently buffeted the slopes of the Rocky Mountains. The best solution, it turned out, was to spread waste rock from a nearby mine over the tailings to provide a footing for vegetation, apply a mixture of biosolids and wood chips over the rock, then plant high-altitude grass seed and shrubs.