Erosion - Mining and the Environment: From Ore to Metal - page 785

will not cause signii cant economic or environmental damage, controls may be established
according to standard engineering practices. If failure potentially leads to loss of life or
to signii cant environmental damage, retention basins should be designed more conserva-
tively in order to withstand the 'Probable Maximum Rainfall Event'. Erosion and sedi-
ment controls should be assessed for economic and environmental feasibility, considering
all costs, including those of environmental impacts and the costs for ongoing, long-term
maintenance.
Erosion and sediment controls should be planned and designed as a sequence of compo-
nents that incorporates the following i ve potential measures ( Figure 20.4 ): (1) minimizing
land disturbance; (2) managing run-on to disturbed areas; (3) managing drainage within
disturbed areas; (4) managing ground cover; and (5) managing runoff and sediment exit-
ing disturbed areas. These are listed in priority order, as the aim is to favour preventative
measures, minimizing the need for corrective measures and repairs.

FIGURE 20.4
The Water Erosion Prevention and
Treatment Train

MANAGEMENT FOCUS CONTROL MEASURES (examples)

Minimizing Land Disturbance

Total Area of Disturbed Land
Planning
Construction supervision
Work in stages
Backfilling concurrent to removal
Temporary and permanent vegetation

Avoid

Abate

Remedy

Compensate

Controlling Water Entrance Rainfall

None
Run-on
Diversion
Berms
Pass-through structures

Avoid

Abate

Remedy

Compensate

Slope length and gradient
Terraces
Tillage
Ground cover management
Mulch and/or vegetation
Rock cover
Supporting Practice
Silt fence
Contouring

Managing Site Drainage
and Ground Cover

Avoid

Abate

Remedy

Compensate

Controlling Exit Runoff Runoff/Sediment Loss

Retention basin
Discharge point
Collection ditch
Sediment trap
Vegetation strip
Constructed wetland

Avoid

Abate

Remedy

Compensate