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Actual inflows into even fractured bedrock would be less than 1/10 of the total precipitation in a precipitation event. The notion that 1/10`h of the surface precipitation could actually reach bedrock mudstone is unrealistically high, and therefore conservative for modeling purposes. While this input assumption would tend to generate greater appazent attenuation by dispersion, it also speeds the apparent travel time. 5. The assumption that native rock units are more transmissive than actual measurements for those units and/or published ranges for similar lithologies is a conservative assumption. The assumption of azbitrarily high transmissivities would speed the flow of contaminants through the formation. 6. The assumption of neutral pH, after equilibration with carbonate-bearing host rocks, is moot to the dispersion calculations. 7. Dilution of U concentrations as a surrogate for dilution of other contaminants (Al, As, Pb and Se) is acceptable. Dilution by 1000x of any of the pazameters that exceeded standards according to the SPLP results is conservative. Overall, the Division accepts that the model results and modeling approach are conservative insofar as their utility for predicting worst-case condition for transport of contaminants through unsaturated media. Despite the conservativeness of the dispersion model input pazameters, the model interpretations rely in some cases on information that is presumed or inferred. The following critique identifies further shortcomings in the model interpretations, and lays out data gaps that would need to be filled in order for the model interpretations to be acceptable. SM-18. The Division accepts that contaminants from waste rock piles or underground workings within approximately % mile of the SM-18 / Wright mine dump would be sufficiently diluted well before reaching the water table. The Division therefore should no longer consider SM-18 mine to be a Designated Mining Operation, unless new evidence justifies reconsideration of this conclusion. JD-9. The Division recognizes that the mine is being developed in a zone that requires pumping water from a perched aquifer in the Salt Wash member of the Morrison formation. The Division accepts that water quality of this perched aquifer, while quite saline, is still what the Safe Drinking Water Act would consider a US Drinking Water source (USDW), because it has TDS concentrations less than 10,000 mg/L. Contaminants cannot be dischazged into a USDW without permit, so water quality there is protected by regulations promulgated under the Safe Drinking Water Act, which is reflected in the groundwater regulations of the Water Quality Control Act, which in turn is the Act to which the Division defers in carrying out our implementing agency authority for groundwater. The operator's inference that the Division needs not be concerned with discharges into aquifers having TDS concentrations greater than 500 mg/L TDS is in error (see Water Quality Control Commission, Basic Standards for Groundwater, Regulation 41). Because the mined material has the potential to release acid and toxic substances in excess of groundwater standards, based on SPLP results, it is evident on its face that re-flooding of underground workings with perched aquifer water from the Salt Wash formation would have the potential to violate state-wide standards. Therefore, the Division considers that the JD-9 mine is a Designated Mining Operation. The operator may elect to have this determination reconsidered by identifying in more detail the quality of water in the perched aquifer and conducting appropriate, representative (not conservative) water-rock interaction tests or other leach tests to support a revised interpretation. Until such results are received, this operation should be considered a DMO, and the operator should take measures to construct