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'ARLITransit Mix Concrete Co. <br /> 444 E.Costilla Street,Colorado Springs,CO 80903 Office: (719)475-0700 Fax: (719)475-0226 <br /> A representative of the qualified blasting contractor, along with a Transit Mix <br /> employee will layout the pattern that is to be drilled. Typically the blast holes will <br /> be drilled in a vertical orientation. Holes will be angled only as needed to <br /> construct the final bench geometry, for specific design features or to address an <br /> unusually irregular face profile. Where angled holes are required,the quarry <br /> manager, in consultation with the qualified blasting contractor, will determine the <br /> appropriate angle based on survey or mine plan. <br /> Hole depths will range from 10 ft. to 45 ft. which includes up to 5 ft. of sub drill <br /> depending on ground conditions, burden and where the hole is located in the <br /> pattern. The number of holes on each pattern will vary depending on the size of <br /> the area cleared and what the current tonnage needs of the operation are. Drill <br /> logs will be recorded for each blast. Holes will normally be drilled on a staggered <br /> pattern on the bench top. Holes will be drilled on a square pattern on an as needed <br /> basis determined by the qualified blasting contractor to facilitate development of <br /> ramps, sumps etc. <br /> Figure 1 below shows a representative blast pattern design layout(staggered)reflecting <br /> the typical blast pattern designs described above. <br /> Typical Blast Pattern Layout <br /> Burden Blast Hole <br /> Spacing �• • • <br /> E <br /> Burden <br /> • • Spacing • <br /> Bench Open Face <br /> FIGURE 1: Typical Blast Pattern Layout <br /> 5 <br />