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<br />h) Weather: Weather conditions were very good. The day was clear and dry. The wort: site was <br />relatively Flat and well maintained. "temperature was in the 50's, as it had been for minty a <br />previous day. There was a brisk breeze coming out of the west. A weather front was most <br />likely moving into the area. There was no prior freezing-thawing or precipitation event <br />before the event that could have loosened the rock wall. The hightvall is examined each shift <br />for safety and no unusual conditions were observed or noted. <br />cj Drill Pattern. Drill pattem was drilled out before the loading crew came on site. There were <br />64 holes in this pattem, 8 rows of 8 holes per row. Rows were laid out approximately on a <br />41 degree angle from the high wall . The drill pattern was a 13 ft x 15 ft, staggered pattem. <br />Blast hole diameter was a nominal 6.25 inches and average hole depth was 45.75 feet. The <br />minimum horizontal distance from the nearest borehole on the east limit of the shot was <br />approximately eight feet. The minimum horizontal distance from the nearest borehole on the <br />south limit of the shot was approximately nine feet. Most outside holes were further that the <br />distances just stated. I personally examined the pattern the previous day and the morittg of <br />the shot and found no alarmingly close holes to any free face. I also noticed that the bore <br />(toles were consistantly drilled on the designated pattem dimensions. 1 was impressed with <br />the drilling practices and precision. <br />d) Explosive loading procedure. Standard loading procedures were used by the loading crew. <br />The bore holes were first measure for total depth and any water found itt them was noted <br />for further reference . 63 holes out of the 64 were loaded with ANFOhvet-bas combination. <br />The remaining one "wet" hole was loaded with emulsion. The bore hole that vented out the <br />side was loaded with ANFO. The relative powder factor was approximately l .l 1 IVs/BCY <br />for the entire shot. We have been using this powder factor for better tlta» a year will good <br />results and predictability. All holes were stemmed with washed gravel to a depth of <br />approximately nine feet. Nine feet of washed gravel has always contained the blasting <br />energy very well in the vertical and horizontal direction, it did on this shot as well. It has <br />been WFC's experience that eight feet of washed gravel stemming or natural ground would <br />contain the blast energy but an extra foot was nice for an extra degree of safety. The surface <br />delay detonation sequence was pre-planned to "pull" the shot to the southeast at 30 degrees.. <br />This sequence was chosen to utili2e [he two free faces and to maximize the amount of <br />material cast into the open pit due east of the blast. The primary open face was due east and <br />the secondary free face was due south. <br />e) At approximately 9:30 am, ]came on the blast site to verify the progress of the loading <br />procedure. To my amazement, the crew had completed the actual loading of the bore holes <br />with explosives and stemming. They had already begun connecting the surface connectors <br />in the approved sequence. This was standard procedure. Basically, they were wav_ ahead of <br />the scheduled noon blasting time frame and the possibility of detonating the shot curly <br />existed. 1 took a quick look at the shot and surrounds and saw no alarming conditions. As <br />1 was confirming the readiness of the pattern with Cliff, we both heard a loud crashin~~ of <br />rocl: coming from the south east corner of the pattern. We walked over and discovered that <br />C;tdata~.wpdata\rlg\blast412.doc <br />