Laserfiche WebLink
Geochemica] attenuation of potential leachate would occur as liquid is transmitted <br />through the bedrock formations. The Salt Wash Member is about 120 feet thick with <br />surdstones totaling about 90 feet in thickness and contauring calcium carbonate cement. <br />Geochemically, this calciwn carbonate would buffer any solutions exiling the repository, <br />The Salt Wash member also contains about 30 feet of shale. Tests on Salt Wash shales <br />indicate Cation Exchange Capacity (CEC} values ranging from 9.9 meq/100 g to 32 <br />meq/100 g and a pH of approximately 8.4. These tests indicate that the Salt Wash <br />shales could attenuate contaminants contained in repository seepage. [See page 15 <br />of Decision Analysis. Emphasis added.] <br />F. Cotter Answered the Division's Questions. <br />After more meetings with the Division, Cotter asked GeoScience to respond to the issues <br />rwsed by the staff. The report prepared on behalf of Cotter by GeoScience dated Febn~ary 7, <br />2006 responds to the Division's January 17, 2006 letter review. After a detailed review of the <br />questions raised by the Division related to the PORFLOW Multiphase Transport Model, the <br />GeoScience report concludes in part, "The implications of this analysis suggest that <br />infiltrating water would actually dilute groundwater concentrations of species of concern. <br />Realistically, the impact from the waste rock piles on the underlying groundwater quality <br />would be `negligible'." <br />The GeoSciences' report also states, "The modeling simulations used in the Cotter Mine <br />reports used a zero value for sorption that is unrealistic but still results in contaminant migration <br />rates that failed to reach the water table." <br />Notably, the February 7, 2006 GeoScience report concludes at page 5 that, "In <br />summary, modeling predictions using several conservative assumptions indicated that the <br />waste piles from uranium mining operations at the SM-18, JD-6, JD-8 and JD-9 mines pose <br />minimal impact to the environment." This GeoSciences' conclusion is based on the following <br />factors: <br />10 <br />