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conservative answer, the skeptics should be satisfied. If it does not, then the Division might ask for more measurement to constrain the degee of sorption within this stratigraphic column. As explained in the phone conversation [with Cotter Corporation] it appeazs that the model does provide for sorption ofmulti-parameters, however the text should better present input assumptions regazding the type and availability of the absorbing materials. [Emphasis added.] After more meetings with the Division, Cotter asked GeoScience to respond to the issues raised by the staff. The report prepared on behalf of Cotter by GeoScience dated February 7, 2006 responds to the Division's January 17, 2006 letter review. After a detailed review of the questions raised by the Division related to the PORFLOW Multiphase Transport Model, the GeoScience report concludes in part, "The implications of this analysis suggest that infiltrating water would actually dilute groundwater concentrations of species of concern. Realistically, the impact from the waste rock piles on the underlying groundwater quality would be `negligible'." The GeoSciences' report also states, "The modeling simulations used in the Cotter Mine reports used a zero value for sorption that is unrealistic but still results in contaminant migration rates that failed to reach the water table." Notably, the Februazy 7, 2006 GeoScience report concludes at page 5 that, "In summary, modeling predictions using several conservative assumptions indicated that the waste piles from uranium mining operations at the SM-18, JD-6, JD-8 and JD-9 mines pose minimal impact to the environment." This GeoSciences' conclusion is based on the following factors: 1. Model predictions show that after 1,000 years of transport, no species of concem reached the underlying water table; 2. Concentrations at the leading edge of the plume aze significantly lower than the background concentrations in the underlying aquifers; 8