years, significant improvements have been made to tailings management practices to isolate mine waste from the environment, and belowgrade disposal practices have been developed specifically to address concerns regarding tailings dam failures. However, the short period of monitoring data at these sites provides insufficient information from which the committee can judge the long-term (200- to 1,000-year) effectiveness of modern uranium tailings management facilities in preventing groundwater and surface water contamination. The potential long-term environmental effects posed by uranium mining and processing waste (e.g., wide-spread groundwater and surface water contamination) are likely to be more than trivial if waste management facilities fail to perform as designed. Major failures would necessitate aggressive remediation strategies and possibly long-term active site management to limit off-site migration and restore the affected area.
• Significant potential environmental risks are associated with extreme natural events and failures in management practices. Extreme natural events (e.g., hurricanes, earthquakes, intense rainfall events, drought) have the potential to lead to the release of contaminants if facilities are not designed and constructed to withstand such events, or fail to perform as designed. The failure of a tailings facility is one example of a design failure that could have widespread human health and environmental effects. Extreme weather events are not rare in Virginia, and need to be carefully and appropriately considered in facility design, management, and maintenance. Management issues or human error, as well as criminal acts such as intentional release, could lead to large-scale environmental contamination by hazardous materials or radionuclides used or stored on-site. The empowerment of all regulatory and mine- and processing-site staff to report and address deficiencies can reduce such occurrences or minimize their impacts. Thoughtful environmental monitoring design can also lead to early detection of contamination caused by management failures, thereby lessening the extent of any offsite remediation that might be required. Until comprehensive site-specific risk and vulnerability assessments are conducted, including accident and failure analyses, the short-term risks associated with natural disasters, accidents, and spills remain poorly defined.
• Models and comprehensive site characterization are important for estimating the potential environmental effects associated with a specific uranium mine and processing facility. A thorough site characterization, supplemented by air quality and hydrological modeling, is essential for estimating the potential environmental impacts of uranium mining and processing under site-specific conditions and mitigation practices. Ongoing water and air quality monitoring are necessary to confirm model predictions and provide the basis for updating and revising these models as additional site-specific data become available.