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Step 4: Estimate Consequences of Failure Consequences of a tailing dam failure can be defined by a number of different factors, including potential for loss of life or injury, property damage, and environmental damage. Specific quantified downstream flood hazard (consequence) information is not available, and would require analyses based on ground surveys, dam break modeling and flood routing, and tailing flow modeling. Lacking this information, a qualitative approach was used with descriptive categories that take into consideration potential consequences in terms of loss of life or injury, property damage, and environmental impacts associated with release of water and tailing to downstream habitat. The broad consequences category descriptions used for this PFMA are summarized on Table 5. The consequences categories defined on Table 5 were developed, in part, from consequence category descriptions that are used by various agencies for dam - safety reviews of traditional water - retention dams. A failure of the San Luis Tailing Facility dam, which under normal operations impounds predominantly drained and consolidated tailing materials and a relatively small free -water pool situated several hundred feet upstream from the dam, would likely have different downstream consequences compared to a water - retention dam of similar size that stores only water. Consequently, the descriptions for the consequence categories have been modified for this analysis to reflect those differences and are considered conservative for purposes of this semi - quantitative risk analysis. Table 5 Consequences Categories Consequence Description Level 0 No significant impacts to the downstream population other than temporary minor flooding of roads or land adj acent to the river. No measurable environmental impacts. 1 Downstream discharge results in limited property damage and /or minor environmental impacts. Damage is likely to recreation areas, roads, and bridges in low -lying areas. Small risk of serious injury, but first aid may be necessary. 2 Downstream discharge results in moderate property damage, and /or significant environmental impacts to downstream habitat that is reversible. Small risk of fatality, or potential for serious injuries, related primarily to difficulties in warning and evacuating recreationists /travelers. 3 Downstream discharge results in significant property damage and /or significant, long -term environmental impacts to downstream habitat. Some potential for fatality, or severe injury or disability likely, related primarily to difficulties in warning and evacuating recreationists/ travelers and /or larger population at risk with significant warning time. 4 Downstream discharge results in extensive property and /or long -term and large environmental impacts on downstream habitat. Fatality or multiple fatalities can be expected due to limited warning time for population at risk. San Luis Project Miller Geotechnical Consultants Tailing Dam Data Report 39 February 2014