2016-06-29_REVISION - M1981185 (3)

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Wildcat Mining Corporation May Day and Idaho Mine and Mill Application 112(d) Permit – Technical Revision No. 1 May Day and Idaho Mine M-1981-185 Revised June 30th, 2016 4 2) Background The mine portal was modified in 2008-09. The mine portal collapsed in the first quarter of 2009. Portal repair activities were addressed when other site remedial activities were completed. In March of 2011, Dr. Gonzales a certified professional geologist was retained to provide a site reconnaissance assessment (Attachment 1) to determine the cause and effect of the portal collapse. Mountain Man Surveying surveyed the May Day No. 1 bench and portal area in 2011 and again in 2016 (Figure 1-“As-Built” Drawing). In 2011, portal and bench geotechnical characterization was conduct by R Squared, Inc. (Attachment 2) and other contracts were initiated to develop a portal stabilization plan and a CDRMS technical revision (TR). The retained contractors included: • R Squared, Inc.; (Bench Geotechnical Characterization); • Mountain Man Surveying: (Map Base and As-built Preparation); • Manhard Engineers; (Technical Revision Development); • EnviroGroup, Limited; (Technical Revision Development); • Trautner Geotechnical, LLC (geotechnical engineers); • Franklin Drilling and Blasting, In. (Rock Bolt, Mesh and Headwall Stabilization); and • Melcher Brothers (Portal Set Design and Construction) 3) Approach Project activities; • Reviewed site aerial photographs; • Reviewed and assessed historical bench geotechnical data (Attachment 2); • Received CDRMS –Technical Revision Approval (Attachment 3); • Conducted field slope measurements; Collected information to finalize rock anchor installation and foundation and head wall geotechnical testing; • Hand excavated tests holes above and below the headwall; to identify potential tension cracks and other conditions that could influence portal instability; • Obtained laboratory testing soil and rock material for engineering analysis; • Reviewed foundation moisture characteristics, • Conducted the following analytical tests including: o Moisture content and dry density; o Atterberg Limits used for general classifications; o Sieve analysis tests to assess the drain distribution of the samples tested; and o Direct shear test to assess strength characteristics; • Observed cut slope excavations to confirm the slope inclinations and material physical construction characteristics.