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BLAST DESIGN AND LAYOUT <br />After the area is deemed satisfactory for layout, measurements are taken of the surface area <br />dimensions of the proposed blast area desired and of the thickness and types of material and if there is <br />a free face existing. <br />The quarry manager, in consultation with the qualified blasting contractor, will design an <br />appropriate drill pattern to ensure safe and efficient production in each area of the quarry. This <br />includes the burden and spacing design, hole depth, number of holes, explosive densities, initiation <br />sequencing pattern, stemming and other factors included in general blasting practice. <br />All owned and non -owned structures are located and the distance to these structures is <br />measured and recorded. <br />The following is the blasting design used mostly in the past and will be used in upcoming blast <br />unless the parameters change. Note that thicknesses of the subsurface geological strata do vary which <br />require different hole patterns and/or different drill hole sizes. <br />The thickness of the sandstone structure that will be shot typically varies from 11 ft to 25 ft. and <br />the clay (if it is of a hardness needing to be shot) varies from 4 ft. to 15 ft. Note that the sandstone <br />thickness can exceed 25 feet in which case the sandstone will be benched and will necessitate a double <br />shot. For example the nearest non -owned structure to Area A is the Miller residence that is <br />approximately 790 feet from the permit line. In area A the next phase of blasting will be approximately <br />1,060 feet west of the permit boundary or more than 1,1850 ft from the closest structure. <br />Typical blast design parameters <br />Hole diameter = 3 Y' <br />Pattern = 8x8 or 7x7 or tighter (depending on depths — shallower depths would require a <br />tighter pattern) <br />Primers = 200 gram and 350 gram cast booster <br />initiation = non electric shock tube <br />Bulk explosive used = anfo or titan emulsion at 1.05 g/cc final density (when the explosives are <br />loaded into the hole, the blaster will monitor the rise of the explosive column with a tape <br />measure and stop the loading when the desired stemming height is reached. This is done an <br />every hole loaded.) <br />Timing = 25ms from hole to hole and 42ms to 84ms from row to row <br />Stemming = crushed stone from the top of the explosive to the surface, typically 5 ft to 8 ft. <br />The pattern is laid out on the ground by the blaster and the holes are drilled to the depth as <br />determined by the thickness of the rock structure. The holes are protected with a hole plug so that no <br />loss to the depth occurs until the day of blasting. <br />Once the pattern is drilled, the blast is scheduled. <br />4 <br />