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Second Submittal <br /> 5.0 MODEL PREDICTIONS <br /> The previous four sections of this report describe the building of the numerical model to <br /> provide a base upon which potential impacts from LRM's proposed operations can be <br /> evaluated. The good calibration provides a high level of comfort that the model can <br /> accurately identify problematic areas that might produce impacts from the operational <br /> scenarios. <br /> The overall mine plan related to groundwater is to excavate a dewatering sump and remove <br /> groundwater to the water management pond where water is re-infiltrated into the alluvial <br /> aquifer. From the initial sump excavation, mining will progress and is described by five <br /> phases depicted in Figures 13 through 15. A perimeter drain (Figure 15) will be placed <br /> along the outer perimeter of the excavation that will serve during mining to dewater the toe <br /> of the high wall to maintain stability, and direct groundwater to the dewatering sump. As <br /> reclamation materials become available,a compacted earth barrier(i.e.,sometimes referred <br /> to as a seal or liner) will be installed over the perimeter drain such that the drain is <br /> hydraulically connected tq the surrounding alluvial aquifer and hydraulically separated <br /> from the interior of the gravel pit. Once the gravel pit perimeter is entirely sealed, the <br /> perimeter drain will serve to route groundwater around the barrier by maintaining a high <br /> permeability adjacent to the compacted backfill. <br /> Five phases of mining describe the mine plan and are modeled to predict potential impacts <br /> on the groundwater system. Sealed portions of the mine pits were simulated as no-flow <br /> boundaries. The perimeter drains were simulated using a higher hydraulic conductivity at <br /> a factor of 2 times higher than the CDSS value used for the rest of the model. This <br /> conductivity value is lower than the calculated equivalent (Appendix F) hydraulic <br /> conductivity that the drain system will provide, lending a level of conservatism to the <br /> predictions. <br /> Most wells in the area range in depth from 5 to 20 feet. Thus, for the purposes of describing <br /> modeling predictions, we considered drawdowns of five feet or more during the irrigation <br /> season (when wells are used) to indicate a potential area for concern from dewatering <br /> Loveland Ready-Mix Concrete 17 Telesto Solutions,Inc. <br /> 20180112�ruwx�u,q t�may_z�.��nnunal air January 2018 <br />