1995-04-17_GENERAL DOCUMENTS - M1977451 (4)

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geochemical environment, these may form soluble sulfates or carbonates or may be lost to groundwater. From the Division' s perspective, the physical chemistry of such processes is distant in importance to the degree of weathering in small areas over short periods of time and their relation to environmental or human receptors. The chart (Figure 13) indicates that these two minerals are soluble, and therefore potentially available to the natural environment. It remains to be told whether under the conditions at the Ike mine these may be released or accumulated in abundances that would cause environmental damage. To show that these materials are not weatherable in significant quantities we would need leach tests of the ore and waste showing what toxic materials are released, how much, and how much would be available at the first point of use. Eh-oH Diagrams. The Eh-pH diagrams are useful for delimiting the equilibrium stability fields for minerals within the simple systems they describe. However, variations in these fields will appear as other components are added; a condition that one should certainly expect in the natural environment. Several things cannot be predicted from Eh-pH diagrams. The behaviour of contaminants in non-equilibrium systems cannot be known from Eh-pH studies. Reaction of any solid or other species shown on the Eh-pH diagrams that can be expected in natural systems is depicted only in equilibrium terms. As equilibrium implies systems at rest, the products - and therefore the potential contaminant contribution - of components in response to interaction with fluids other than pure water cannot be known. Kinetics of reactions. As all of the presented arguments depend on equilibrium systems, there is an understandable dependance on qualitative terms to define rates of reactions. The speed at which a given material will form, or re-combine, or dissolve is expressed in relative terms and, for the most part, cannot be of quantitative use for describing the system under natural conditions. This is not a fault of the authors or of the studies they utilize; rather it is a fact of the state of knowledge. Real time tests should be employed to quantify the statements whose consequences may affect the environment that may result from mining and post-mining weathering. Standard leach tests, a review of which the Division can provide, will help quantify the problem. CONCLUSIONS Potential receptor systems that could be affected by mining activities at the Ike No. 1 property, and that were considered in this review, include air, surface water, and groundwater. Soils and plant life, were not considered in my review. The fundamental conclusion of the Cotter report is apparently that the mine wastes will weather in such a way that they will not release toxic substances in quantities of consequence to these receptor systems. Although the arguments are compelling with regard to equilibrium systems, they are not convincing when considered in context of the weathering environment. Uraninite and coffinite, the principle ore minerals, are soluble in natural waters. Uranium and vanadium, in their intermediate states between these two minerals and other, consequent, uranyl- or vanadyl-carbonates or phosphates, are mobile and potentially available to the environment via air and water pathways. The concentrations or uranium that would be considered toxic to aquatic life appear to be very high relative to the average grade of ore in the Colorado Plateau. However, the concentrations of vanadium are considerably lower, and should be evaluated with greater scrutiny than uranium. The concentrations of other metals are considerably higher than crustal abundance averages, and indicate that they should be evaluated for potential environmental consequences.