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6. A simple dilution model, which dismissed the effects of sorption, was submitted subsequently. Explanations of the model raised questions that are the subject of the remainder of this review. The original submittal, dated November 2, 2005, provided transport simulations for contaminants that were identified as potential contaminants from the results of SPLP tests of the ore and waste. These simulations presumed that sorption would help contain contaminants. The Division responded, informally, that the simulations that assumed sorption throughout the stratigraphic column were unconstrained, and therefore were not conservative. GeoScience Services responded with a more conservative, albeit less complete, model simulation, which was submitted via E-mail and dated November 28. In particular, the second submittal provided a simple dilution model only, and dismissed the potential effects of sorption. The Nov 28 submittal approaches DMG's requirements that the simulation be run under conservative conditions. However, backup information is lacking. Before agreeing with the model results, the Division should be provided a report containing all of the input parameters, and answer the following questions. ^ Please list the presumed concentrations of regulated parameters. ^ Please clarify the composition of simulated rainwater used in the SPLP tests. The write- up appears to indicate that rainwater (snowmelt) pH is neutral, which is not correct. ^ Please identify the transmissivity of the various units as used in the model, and indicate whether the transmissivity was measured or assumed ^ Please furnish a more detailed explanation of how faulting in the area of these operations impacts contaminant transport and explain what if any consideration was given to those issues in the modeling. ^ The Division requests a depiction of the water table on the model results and an indication, in the text, of how closely contaminants will travel relative to the water table. ^ Please supply the Division with the background TDS value for the perched aquifer. ^ Please state all other input parameters and assumptions that are implicit in the model. This report should be submitted in paper form, per Division policies, and signed by the author. We agree that sorption should retard the movement of contaminants through the stratigraphic column. The actual amount of sorption, however, has not been quantified, so cannot be permitted in the models to act in an unconstrained fashion. If the ultra-conservative approach of assuming zero sorption provides a simple way to reach the hoped-for, conservative answer, then skeptics should be satisfied. If it does not, then the Division might ask for more measurements to constrain the degree of sorption within the stratigraphic column. As explained in the phone conversation, it appears that the model does provide for sorption of multiple parameters. However, the text should better present input assumptions regarding the type and availability of the sorbing minerals. The November 28 submittal should be augmented to explain more than the diagram portrays. For instance, from the diagram it appears that the contaminant plume approaches the cliff face in the cross-section, Given that some of the mines are closer to the mesa face than others, it remains questionable based on the diagram whether the plume might discharge at the cliff face 4