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Blast Reconstruction Comments Colowyo Coal Company, Mazch 28, 2003 In response to CDMG's letter dated Mazch 11, 2003, and the analysis of the blast on February 16, 2003, 4:04 PM, Cut No. 63, Station 34+00 to 44+00 Blast record. Following aze Colowyo's analysis of the blast, as well as comments on the assumptions and results from that analysis. Upon completion of Colowyo's analysis, the following table has been developed Colowyo CDMG Analysis Analysis Blast Record Number of Holes 189 189 189 Feet of drilling 14,012 14,012 14,012 Total pounds of explosive 421,184 422,084 438,644 Distance to nearest dwelling 3,160 3,160 3,160 Pattern Layout 23' x 33' 23' x 33' 23' x 33' Delay Layout and Locations See Blast Report See Blast Report See Blast Report Drill Logs -Holes Missing 5 5 5 Max number of holes detonated per 8ms period 4 3 1 Max Wt. of explosives allowed per 8ms period 3,303 3,303 3,385 Max Wt. of explosives used per 8ms period 9,135 7,055 2,970 Comments: 1) CDMG's analysis showed 189 hoes, 14,012 feet of drilling, and 421,1841bs of explosive. The calculations for the number of holes and feet of drilling are supported. The number of pounds in the pattern were adjusted based on Comment 5. 2) CDMG's analysis assumed 14 feet of stemming. This assumption is supported. 3) The pattern spacing was 23x33. In the design statements on the spreadsheet it was indicated that the holes were separated by 25 feet, however in the calculation for shock tube between cords the analysis was done with 23', therefore the analysis was not in error in this regard. 4) The shock tube distance between holes appeazs correct. An assumption that the lead in time to G row was 16.5'; too B,D,F row the length was the burden too the row; and to A,C,E row the burden plus %z the hole spacing. These assumptions are supported.