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Response to Geochemistry Review - May Day Conversion CN-1 <br />File No. M-1981-185 <br />As contemplated by the Joint Stipulation and clarified in the Division's preliminary adequacy <br />letter, dated 15 March 2011, the Operator may not be able to adequately characterize the ground <br />water regime until after CN-01 is issued. However, CN-01 must include a detailed plan whereby <br />the ground water regime may be adequately characterized. The plan may not be implemented <br />until after CN-01 is issued but such plan must be reviewed now, as part of CN-01. <br />Response #15 <br />See the groundwater response provided in Response 5 and Attachment H. <br />Adequacy Issue #16 <br />Exhibit T - Environmental Protection Plan; Rule 6.4.20(14)(d) [Rule 6.4.21(14)(d) under the <br />Hard Rock Rules effective Sept. 30, 2010], page 14. The Applicant states that the pH of the <br />mined rock is 7.5. Please describe how the pH of the rock was measured. <br />Response #16 <br />The paste pH procedure was used to measure rock pH. <br />Adeauacv Issue #17 <br />Exhibit T - Environmental Protection Plan; Rule 6.4.20(14)(d) [Rule 6.4.21(14)(d) under the <br />Hard Rock Rules effective Sept. 30, 2010], page 14. The Applicant states that there is no <br />pathway to the drinking water. In the opinion of the Division, a potential pathway to drinking <br />water exists in the form of ground water migration from the mine workings to the La Plata River. <br />Therefore, appropriate monitoring must be implemented as described in bullet 6.C above. <br />Response #17 <br />Dry stack underground tailings disposal methods have been adopted to eliminate potential <br />water quality concerns with the mine operation An appropriate groundwater and surface <br />water monitoring and point of compliance programs will be established to demonstrate <br />compliance with applicable water quality standards. <br />Adequacy Issue #18 <br />Exhibit T - Environmental Protection Plan; Rule 6.4.20(14) [Rule 6.4.21(14) under the Hard <br />Rock Rules effective Sept. 30, 2010], Geochemical Data and Analysis, page 14. In addition to <br />the Acid-base accounting and SPLP analyses, the applicant is required to submit one sample of <br />tailings for a long-term humidity cell test under ASTM method D5744-07. The sample to be <br />submitted shall be selected in consultation with DBMS. The test shall commence as soon as <br />possible and continue for the life of the project or until permission is received from DRMS to <br />discontinue the test. Specific parameters of the test are shown in the table below. As the long- <br />term results of these humidity cell tests will have a bearing on the technical practicability of the <br />May Day Idaho Mine Complex 112(d) Permit Application <br />Revised: April 14, 2011