Erosion - Mining and the Environment: From Ore to Metal - page 786

FIGURE 20.5
Using Down-slope Vegetation Cover
to Dissipate Energy from Runoff
and to Collect Eroded Soil Materials

This sequence enables the management of all factors that contribute to erosion, except
precipitation. Clearly, the best management measure is to avoid land disturbance alto-
gether. The least desirable management technique is the management of sediment-laden
water leaving the site, which is a corrective measure responding to soil loss that has already
occurred. Key points in managing surface water erosion as summarized in Figure 20.4 are
discussed below.

Minimizing Land Disturbance
Minimizing land disturbance should be a priority of project planning. An erosion man-
agement plan should be formulated at the beginning of mine development and carefully
followed. Very often this is not done, leading to patchwork solutions which may create
problems in the future.
Before the mine plan is developed, the entire mine area should be carefully surveyed.
Construction and engineering structures, layout of supporting facilities, transport routes
and mining technology should all be compatible with the terrain, landscape and ecosys-
tems of the site area such that land disturbance is minimized.
Any feasible preservation of natural vegetation cover during the construction and oper-
ations periods should be planned before site disturbance begins. One major advantage of
such preservation is the capacity of natural vegetation to handle increased runoff resulting
from adjacent land disturbance. A vegetative buffer strip running across a slope dissipates
the energy from runoff; small barriers may be installed within the strip to collect sediment
( Figure 20.5 ). This method is most appropriate where there is no well-dei ned channel
coming from the disturbed land.
Implementation of the erosion management plan is often neglected during the construc-
tion phase if the construction contractor is not contractually obliged to adhere to commit-
ments made, and if not properly supervised. Ensuring that equipment operators understand
survey markings and do not exceed the limits of work sites minimizes land disturbance.
The correct equipment for earthworks should be used, since equipment that is too light or
too heavy can have detrimental effects on erosion, besides delaying completion of site work.

An erosion management plan
should be formulated at the
beginning of mine development
and carefully followed.