Design and methods

• Pages: 16-21

16

6. Design and methods

6.1. Design requirements

6.1.1. Where the depth of an opencast mine excavation is planned to exceed 10

m, the mine operator should, prior to the commencement of excavation, prepare:

6.1.1.1. a design report; and

6.1.1.2. an operating manual.

6.1.2. The design report should include:

6.1.2.1. maps and, where available, recent aerial photographs, showing the location

and physical features of the mine area, including local drainage systems;

6.1.2.2. drawings showing:

6.1.2.2.1. the contours of the ground before any site preparation;

6.1.2.2.2. structural geology in the region of the mine;

6.1.2.2.3. a plan of the mine illustrating the projected five-year plan;

6.1.2.2.4. typical cross-section through the walls; and

6.1.2.2.5. the location of any diversionary drainage systems;

6.1.2.3. the results of any tests, studies and investigations to determine:

6.1.2.3.1. geotechnical properties of the rock and soil in the vicinity of the walls;

and

6.1.2.3.2. groundwater conditions in the vicinity of the mine;

6.1.2.4. the design, position, nature of construction and stability analysis of any

support structures to be incorporated in the walls;

6.1.2.5. a stability analysis including an outline of any design assumptions that were

made; and

6.1.2.6. details of any testing and instrumentation which may be required to monitor

wall or strata movement and groundwater conditions in the region of the mine

to verify the design assumptions.

6.1.3. The operating manual should include:

6.1.3.1. specifications for the configuration of the final mine walls, including toe and

crest positions, planned face slopes, average overall wall slopes, bench widths,

bench intervals and any berm construction;

6.1.3.2. the method and rate of excavation to the final walls;

6.1.3.3. details of any blasting procedure to maintain control of the pit wall;

6.1.3.4. specifications for drainage and dewatering systems; and

6.1.3.5. details including location, method and frequency of reading and of

maintenance of any instrumentation required to monitor wall and strata

movement or groundwater conditions in the region of the mine.