1. Your supervisor is contemplating excavating an underground primary opening at a mine site where a 36 m gold vein, dipping at 60 degrees from the horizontal, outcropping on the surface and open at depth (i.e. drilling has not reached a definitive end to the deposit) was recently discovered. The purpose of the underground opening is to provide access to a level to be located 1,500 m below surface. Given the following two alternatives: (15 points)

1. Vertical shaft access

a) Shaft sinking costs, 6.1 m in diam.: $21,800 /m (vertical)

b) Shaft must be sunk at least 70 m below targeted level

2. Ramp access

1. Ramp excavation, 5.0 m wide x 4.0 m high, -8 degrees: $7,450/ m (linear)

2. Switchback (turnout) required every 250 m drop in elevation (disregard the length of the turnouts in your calculations).

Do the following:

1. Prepare a diagram for each alternative.

2. Given the solid (i.e. in situ ) density of the material (rock) to be excavated is 2650 kg/m³ and a swell % of 40, calculate and compare the volume of the muck (broken rock) to be hoisted or hauled to surface for each of the two alternatives considered for this project.

3. Determine the total cost of excavating a vertical shaft for the project.

4. Determine the total cost of excavating a ramp for the project.

5. Other than the total cost of driving the excavation, what other points would you urge your supervisor to consider before making a decision regarding the type of underground primary access that should be excavated forthe project

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