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December 2, 2005 <br />To: Russ Means ~ <br />From: Harry Posey, Kate Pickford <br />~~ <br />o`~>~, ~F~'~ C~~li <br />FO <br />b ~~ <br />,, ~'6 <br />Zip <br />~~ti <br />RE: Review; Nov 28, 2005 letter from GeoScience Services, re: contaminant transport <br />simulations for Uranium-vanadium ore bodies, Montrose County; M-1977-310, M-1984- <br />014, M-1977-306, & M-1978-116 <br />This does not constitute a complete or final review of the materials that Cotter Corporation <br />submitted in regard to the two groups of U-V ore bodies in western Montrose County. However, <br />it should provide some guidance to the operator and consultant in preparing an acceptable <br />submittal for our review. <br />The original submittal, dated November 2, 2005, provided transport simulations for <br />contaminants that were identified as potential contaminants from the results of SPLP tests of the <br />ore and waste. These simulations presumed that sorption would help contain contaminants. <br />The Division responded, informally, that the simulations that assumed sorption throughout the <br />stratigraphic column were unconstrained, and therefore were not conservative. Hence, the <br />Operator's consultant, GeoScience services, responded with a more conservative, albeit less <br />complete model simulation, which was submitted via E-mail and dated November 28. <br />The current simulation "appears" to meet DMG's requirements that the simulation be run under <br />conservative conditions. However, backup information is lacking. Before agreeing with the <br />model results, the Division should be provided a report containing all of the input parameters, <br />including but not limited to: <br />• concentrations of regulated parameters <br />• composition of simulated rainwater (the write-up appears to indicate that rainwater <br />(snowmelt) pH is neutral, which is not correct); <br />• transmissivity of the various units, <br />• all other input parameters and assumptions. <br />This report should be submitted in paper form, per Division policies, and signed by the author. <br />We do not disagree that sorption will act to some degree to retard the movement of <br />contaminants through the stratigraphic column. The actual amount of sorption, however, has <br />not been quantified, so cannot be permitted in the models to act in an unconstrained fashion. If <br />the ultra-conservative approach of assuming zero sorption provides a simple way to reach the <br />hoped-for, conservative answer, then skeptics should be satisfied. If it does not, then the <br />