Environmental Assessment
Volume E-6
Tailings Facility
Reclamation and Closure
Ambatovy Project
229
January 2006
the material contains or retains topsoil characteristics it will be used in final
surfacing for revegetation. Lacking these properties, the material may be used
for general cover purposes. No stockpiles will remain at the site following the
active closure phase.
6.3
RECLAMATION PLANS
6.3.1
Erosion Control
The following general mitigation options are available to prevent water erosion:
•
salvage topsoil where feasible and store away from areas of potential
erosion;
•
construct temporary cross ditches to redirect surface runoff;
•
construct temporary berms of imported logs, construction timbers,
sandbags or other material as appropriate and available;
•
construct berms with overburden in areas where topsoil has been
stripped;
•
construct mine roads so natural drainage patterns are not impeded and in
a manner that runoff to road ditches enters natural drainage systems or
contoured containment areas;
•
use temporary erosion control measures such as mulches, mats, netting,
or straw crimping to control erosion before establishing a protective
vegetative cover;
•
apply tackifiers where necessary to stabilize soils and use hydroseeders
for seeding on steep slopes; and
•
promptly seed exposed areas and topsoil stockpiles with a self-
sustaining, erosion-controlling seed mix appropriate to the region. It is
suggested that Vetiver grass (
Vetiveria zizanioides
) be planted in strips
across slopes (following contour lines) (NRC 1993). Other species can
then be planted between the strips of Vetiver.
6.3.1.1 Using Vetiver for Erosion Control
Vetiver (
Vetiveria zizanioides
) is a native grass from India that is being used
throughout the tropics for erosion control (NRC 1993). It has been used in
Madagascar for erosion control by farmers and industry for over a decade and is
also suggested for erosion control of mine dumps in the country
(Grimshaw 1997). Users in the tropics for erosion control have reported that
