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Colowyo Coal Company, LP. <br />5731 State Highway 13 <br />Meeker, Colorado 81641 <br />(970)824-1532 <br />(970) 824-1598 FAX <br />G CRELLIN SCOTT <br />Slt ENVIRONMENTAL ENGMEER <br />February 25, 2003 <br />RECE9VED <br />FEB 2 8 2003 <br />Division of Minerals and Geology <br />Mr. Byron Walker, P. E. <br />Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />//= Kennecott <br />~ ®Energy <br />C~~ <br />Colowyo Coa! Company L,P. <br />RE: Response to the CDMG Complete Inspection dated 2/19/2003, by Byron Walker <br />for Permit No. C-81-019. <br />Dear Mr. Walker: <br />As per your completeness inspection of the mine site on February 18~' and 19th, 2003 <br />you have requested that Colowyo Coal Company examine the blasting incident for the <br />February 16, 2003 date, between STA 34+00 to 44+00. Colowyo Coal Company has <br />completed their review including a review of the blasting report, recent blasting <br />practices, and seismographic data. <br />The blasting report was reviewed in more detail including the pattern, number of holes, <br />delays used, distance to the nearest dwelling, drill logs, and pounds of explosive per <br />hole. The data in the blasting report was determined to be accurate with respect to the <br />blast activities. <br />Recently, Colowyo has been experimenting with their blasting practices to further <br />minimize both seismic and airblast impacts. Colowyo is focusing on executing each <br />shot by single shot ignition. This recent improvement is targeted to reduce vibrational <br />impacts. Another improvement has been reducing airblast impacts. Colowyo has <br />recently changed to initiating system by using shock cord versus traditional detonation <br />cord. This has reduced the airblast impact by 10 decibels. <br />Colowyo continuously monitors the shots at the nearest dwelling using seismographic <br />instrumentation. This information measures our performance for each shot event. The <br />seismographic information collected for the February 16, 2003 shot indicates that <br />compliance was maintained throughout the entire shot. Please see the attached blast <br />monitoring data for February 16, 2003 from the Ott's (Durham) ranch. <br />Colowyo encourages the State to take into account the intent of the law regarding blast <br />impacts to nearby dwellings. Seismographic data for this event indicates there were no <br />exceedences to the State regulations and thereby indicating compliance with the <br />blasting standards. <br />