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Geotechnical Stability Exhibit <br />Exhibit 6.5 <br />road which was evaluated in connection with the new access road. The private owner property <br />boundary is approximately 80 feet from the New Access Road cut slope and if the road cut failed <br />(which is highly unlikely) where a final 3:1 slope was created, the land slide head cut would be <br />approximately 40 to 45 feet from the private landowner's property boundary. Recent <br />geotechnical assessments described in Attachment 6.5.3 and Attachment D -1 suggest that the <br />current and final cut slopes are stable. Additional geotechnical studies will be undertaken to <br />support the New Access road design. <br />Blasting Impacts <br />The effects of blasting on adjacent structures have been conducted by Mr. Terry Morris <br />(Colorado Registered Professional Engineer No. 28457) and are presented in Attachment 6.5 5. <br />Mr. Morris concludes that no structural damage is expected using up to 100 pounds of explosive <br />per blast within the Mayday No. 2 underground workings. As the proposed blasting will be <br />undertaken in the Mayday No. 1 underground workings further to the east, the existing blasting <br />analysis is sufficient. As recommended, Wildcat will perform vibration monitoring if the size of <br />the blasts exceed 200 pounds of explosive per delay. It is anticipated that the contractor <br />conducting daily blasting will be Franklin Drilling & Blasting under the permits identified in <br />Attachment 6.5 -5. <br />Predicting surface air and ground blasting vibration is based on research information published <br />on March 8, 1993 by US Office of Surface Mining (OSM). OSM developed the "scaled distance <br />factor (SDF)" which is a conservative and accepted approach to estimating ground vibration <br />without the use of seismographs. For example, if a structure is located from 0 to 300 feet from a <br />blast site, the "scaled distance factor" would 50. If the blast site is located from 301 to 5,000 feet <br />away, the SDF would be 55 and for blasts where the structure is greater than 5001 feet away <br />would have a SDF of 65. Using the OSM SDF, blasting can be used to predict potential impacts <br />according to the following formula. <br />W= (D /SDF) <br />Where <br />W= weight in pounds of detonated explosive in any period greater than 8 milliseconds. <br />D =is distance in feet from the structure of concern <br />SDF = Scaled Distance Factor <br />As an example, <br />Wildcat Mining Corporation <br />May Day Idaho Mine Complex — 112d Permit Application <br />Revised August 2011 <br />Geotechnical Stability Exhibit 6.5 <br />If a structure is 200 feet away from the blast site, the maximum amount of explosives per delay <br />is 16 pounds without the need for a seismograph. Wildcat proposes to use 5 to 10 pounds of <br />explosives at any one time on the road cuts where the nearest structure will be in excess of 400 <br />feet. <br />Page 10 of 11 <br />