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Matheson <br />:• Mining <br />Consultants, Inc. <br /> <br /> <br />March 15, 2008 <br />2801 Youngfield Street, Suite 171 <br />Golden, CO 80401-2266 <br />303-456-5638 <br />Toll Free 888-456-5638 <br />Fax 303-456-5639 <br />www.mathesonmining.com <br />P ~~x <br /> <br />Mr. Timm Comer APR ~ ~ 2008 <br />Cripple Creek & Victor Gold Mining Company <br />P. O. Box 191 1?ivision o~ rceclar~iation, <br />Victor, CO 80860 Mining and Safety <br />Re: Review of Ground Motion Attenuation Studies performed at CC&V. <br />Dear Mr. Comer: <br />Matheson Mining Consultants, Inc. (MMC) was retained by Cripple Creek & Victor Gold <br />Mining Company (CC&V) to review the Ground Motion Attenuation Studies that have been <br />performed by various consultants at CC&V from 1993 through 2004. Five reports have been <br />completed comprised of data sets from seven distinct mining areas and one construction site. <br />Mining areas studied include Ironclad, Globe Hill, Cresson, Ajax, Ridge Road, North Cresson <br />and East Cresson. The results of the studies are remarkably similar except for the construction <br />site study. MMC does not consider the construction site study to be applicable to mine blasting <br />as it was conducted on poorly consolidated material. MMC does not recommend additional <br />ground motion attenuation studies but recommends continued monitoring at the closest non-mine <br />owned structures, including the Molly Kathleen Mine, to continue to demonstrate compliance <br />with permit obligations and all accepted non-damage criteria as outlined by the United States <br />Bureau of Mines Report of Investigations 8507 "Structure Response and Damage Produced by <br />Ground Vibrations From Surface Mine Blasting". Designing all charge weights per 8- <br />millisecond delay period using a Scaled Distance of 35 and confirming the results with an <br />ongoing blast effects monitoring program will restrict ground motion to a maximum of 0.50 <br />inches per second peak particle velocity. <br />Scaled Distance to not exceed 0.50 inches per second peak particle velocity are determined in <br />each of the above noted studies. Below is a table listing the study, date of the report and Scaled <br />Distance relationship: <br />TahlP 1 ~ firnnnd Motion Attenuation Studv Results <br />Mine Area Date Scaled Distance <br />Ironclad 5/25/93 30.66 <br />Globe Hill 5/25/93 34.31 <br />Cresson 5/25/93 25.98 <br />Combined 5/25/93 32.85 <br />AJpX 6/ 13/97 47.59 <br />Ridge Road/Goldfield 6/13/97 34.03 <br />Construction Leach Pad 6/13/97 13.43 <br />North Cresson 3/8/2000 43.80 <br />East Cresson 3/22/04 34.09 <br />