2017-04-26_REVISION - M1977300 - Laserfiche WebLink

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Technical Revision 25 Schwartzwalder Mine ' chemicals, toxic or acid-forming materials and describe how unauthorized discharge of acid mine drainage will be prevented. ' No designated chemicals are currently in use or being stored at the Schwartzwalder Mine site. No acid- forming materials exist onsite. Native rock at the Schwartzwalder Mine is not acid-generating. Instead, it ' is classified as having a low potential to generate acidic drainage, and no acidic drainage has occurred from the mine or waste rock facilities to date. Geochemical characterization of the waste rock piles is described in Section 14 of the Revised EPP. The water quality of the flooded mine workings is described ' in Section 9(b)(iv) of the Revised EPP. The pH of groundwater in the flooded mine is near neutral, and has been stable (no obvious increasing or decreasing trend) since monitoring of mine water began in ' 2000. The mine pool has shown no potential to generate acid. The flooded mine workings and the alluvium and fill have been identified as toxic-forming materials on ' the basis of(1) uranium and radium-226 in groundwater in the underground mine pool and (2) uranium in groundwater in the alluvium and fill. The hydrogeologic conceptual model is described in Section 8(e) of the Revised EPP. Water quality in the mine pool is summarized in Table 9-8 and discussed in Section ' 9(b)(iv) of the Revised EPP. Water quality in the alluvium and fill is summarized in Table 9-3 and discussed in Section 9(b)(ii) of the Revised EPP. Potential mitigation options for groundwater are discussed in Section 15 of the Revised EPP along with a proposed schedule for feasibility investigations, ' engineering design, and implementation. 3.2.3 Geological and Geochemical Conditions ' Section 8 of the Revised EPP presents geological conditions, and Section 14 of the Revised EPP presents geochemical conditions. ' 3.2.4 Monitoring and Sampling Water levels will be monitored in the clean water, treated water, and reactor tanks in the following manner: ' • Water levels within the two, 20,000-gallon storage (treated water) tanks (which are connected via a 4"pipeline) are monitored with a pressure transducer connected to the programmable logic controller(PLC). The PLC maintains the levels within the tanks to a determined height by ' speeding up or slowing down booster pumps that draw from these storage tanks and provide pressure for the RO system. • Water levels within the reactor tank will be monitored by a pressure transducer connected to the ' PLC. Water level control is accomplished by a throttling valve. • Water levels within the clean water tank will be monitored by a pressure transducer connected to the PLC. The treated water tanks and the reactor tank will not be Y sampled routinely. However, the clean water tank will be sampled as required by Cotter's discharge permit CO-0001244. Sampling will occur from a ' sampling port within the NWTP building immediately upstream of the clean water tank, except for pH. ' Mine Permit M-1977-300 Cotter Corporation(N.S.L.) 14 April 2017