干旱区生态环境知识资源中心

Many landfills designed for long-term containment of radiological and hazardous waste are located in arid to semiarid areas. Cover designs for landfills in these areas often include highly durable rock riprap on side slopes to satisfy engineering standards for erosion control. However, the highly durable rock required by the U.S. Nuclear Regulatory Commission is not readily available, particularly on the Colorado Plateau. Furthermore, rock riprap alters the water balance of landfill covers and can enhance water infiltration. Current design guidance does not consider the beneficial erosion resistance and favorable soil water balance provided by vegetation. We suggest that a combination of rock and vegetation is adequate to control erosion over hundreds to thousands of years without increasing water infiltration. We examined the morphology, stability, and soil water balance of a naturally occurring vegetated rocky slope near the Cheney Uranium Mill Tailings Repository south of Grand Junction, Colorado, as an analog of long-term performance. Rock varnish, lichenometry, pedogenesis, and plant succession were investigated as indicators of the relative age and stability of the slope. We also monitored seasonal changes in profiles of soil water content of the upper horizons.