A contractor is tendering for a road cutting to be blasted through a competent dolerite. He asks you for your assistance in designing a pre-split blast using the following parameters. Hole diameter: Vertical depth: Hole angle: 91mm 14.0m 73 There are significant penalties in the contract such that the contractor is prepared to put considerable effort into the drilling and blasting operation so as to minimize over break. You are asked to design the drilling pattern and the blast design and recommend an explosives and initiation system to achieve the best result possible. What should the standoff distance be for the main blast holes? Motivate your answer with the aid of sketches. Clearly state your assumptions. Design a blast with the following parameters. The muck pile needs to be thrown / casted into the void. Rock type: Competent sandstone Strip width: 45m Bench height: 28m Hole diameter: 238mm Explosives: Recommend the most suitable product Initiation system: Electronic delay detonators + 400g boosters Motivate your answer with the aid of sketches (Drill pattern and timing pattern). Clearly state your assumptions and any additional recommendations.