Laserfiche WebLink
Further oxidation of weathered shale in the northern boundary of the Site, as represented <br /> by MW-06 and MW-10 well logs, will likely oxidize organic carbon, but will not affect <br /> iron oxides or alter uranium speciation (already in oxidized form). It is not likely that <br /> uranium concentrations will increase as a result of mining in the northern section of the <br /> Site if the weathered shale is left undisturbed. As for other monitoring wells, where <br /> uranium concentrations are currently well below the Regulation 41 standard, leach tests <br /> show that uranium release under laboratory conditions was minimal. Further,groundwater <br /> in these wells was relatively reduced, yet uranium species remained oxidized, suggesting <br /> that uraninite precipitation/dissolution is not controlling uranium concentrations in the <br /> central and southern sections of the Site and it is more likely that sorption to iron <br /> (oxy)hydroxides sequesters uranium in these locations. <br /> Once uranium is oxidized, it is very mobile. Based on the whole rock analyses, SPLP <br /> testing on oxidized samples,the lack of uranium source in the local alluvial sediments,and <br /> geochemical makeup of the Pierre Shale, it appears that the source of the higher uranium <br /> concentrations is somewhere upgradient of the Site. Given the correlation to nitrate and its <br /> role in oxidizing uranium minerals, the source may be near individual sewage systems. <br /> 3.3 Dewatering/Mixing <br /> Given the conservative nature of oxidized uranium complexes in groundwater,we applied <br /> a straightforward mixing model to evaluate LRM's water management on uranium <br /> concentrations in the water management pond, and the resulting groundwater recharge. <br /> Telesto utilized the estimated inflows to the dewatering cells during different mine phases <br /> (Telesto, 2017) multiplied by aquifer concentrations to get a mass influx of uranium into <br /> the water management pond. We then calculated the evapoconcentration of water using <br /> the maximum, estimated consumptive water use from the Substitute Water Supply Plan <br /> request. The model shows that throughout the first half of mine life of mine, there is <br /> enough water with lower uranium concentrations to dilute the areas of higher <br /> concentrations from groundwater north and northwest of the Site that no pumped water <br /> ever exceeds Regulation 41 Standards. Likewise, the evapoconcentration effects are <br /> minimal (i.e., less than 1 µg/L increase in concentrations). This is because the amount of <br /> 1 ON eland Ready-Mix Concrete 15 December 2019 <br /> 202,u11,k,,,,.,,, hawlme„.,rryudi,iv, ary do, TELESTO <br />