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To: Jared Ebert <br /> Date: December 29, 2017 <br /> Page 20 <br /> — Water movement <br /> • LRM commits to monitoring and managing its water to limit the potential for <br /> water quality issues <br /> While the Pierre Shale is documented to have source constituents available, it is also well <br /> documented that it is highly impermeable. On site, the Pierre Shale drilled dry, meaning <br /> there is no water present. Thus, the only mechanism to move source constituents from <br /> the Pierre into contact water is through molecular diffusion, which is a slow process. <br /> Recently, LRM collected samples of the Pierre Shale at the contact with the alluvium and <br /> subjected the samples to the synthetic precipitation leach procedure (SPLP) testing. One <br /> of 5 samples resulted in detectable selenium. Three groundwater quality samples were <br /> taken from monitoring wells MW-06, MW-13, and MW-02. MW-06 showed detectable <br /> levels of selenium below the drinking water standard. The sample from MW-06 <br /> contained sedimentation (i.e., the well has not completely developed), thus it is most <br /> likely that the detected selenium was part of the solid matrix. LRM will sample MW-06 <br /> again and filter the sample to corroborate this supposition. These data corroborate the <br /> potential for the Pierre Shale to contain selenium, and on the whole, show that ground <br /> water quality is not significantly impacted by the Pierre Shale. LRM's water <br /> management activities keep the groundwater system outside of the mining area in tact <br /> with respect to water contacting the Pierre Shale. Inside the mining area, no water that is <br /> in direct contact with the shale is proposed to leave the site. Thus, no water quality issues <br /> are anticipated. Regardless, LRM commits to monitoring its water quality in the water <br /> management pond and respond accordingly should discharges be an issue. <br /> Comment 40 <br /> Regarding the item discussed above,please provide a rational and any applicable data to <br /> substantiate the claim that groundwater quality will not be an issue. <br /> Response 40 <br /> See previous response and section 5.5.3 of the revised groundwater report. <br /> Comment 41 <br /> The "Natural Areas" will essentially be lined pit excavations that will on average be <br /> about 15 feet deep. After the site is reclaimed, please demonstrate how precipitation and <br /> storm water will not be allowed to stand in the pit? If storm water is retained onsite for <br /> Response to DBMS comments T E l E S T O <br />