Environmental Assessment
Volume E-4.1
Tailings Facility
Flora
Ambatovy Project
161
January 2006
Mitigation to limit the amount of disturbances in the LSA has in part been
achieved through siting design (i.e., locating the tailing facility in a previously
disturbed area). To further minimize the long-term effects of the project on
vegetation, reclamation is planned during the closure phase.
The tailings facility will be re-vegetated in stages after each basin is infilled with
tailings material and soil moisture levels are within an acceptable range for
reclamation purposes. The main objectives of the revegetation program include:
•
control water erosion on tailings embankments and other steep slopes;
and
•
revegetate the remaining areas based on guidance from local
stakeholders and results derived from the reclamation trials program.
Water erosion control on steep slopes such as on the tailings embankments will
be achieved through designed systems and seeding with a self-sustaining seed
mix appropriate to the region (see Volume E, Section 6 for additional
information on reclamation). A research-based reclamation trials program will
be initiated to adequately address the optimal reclamation techniques given the
nature of the tailings material.
Given the uncertainty associated with the type of vegetation that will establish
during the closure period, a worst-case scenario is assumed for the purposes of
this assessment. This scenario states that all woodlots and plantations (7 ha) will
be permanently lost from the tailings area. In the place of these forest types, it is
assumed that some form of secondary forest vegetation will re-establish. Based
on these assumptions and the current general vegetation characteristics (i.e.,
current vegetation not unique to the region and existing in a degraded or
unnatural state), a low environmental consequence is predicted for forest loss.
Table 4.1-3 Residual Impact Classification for Loss or Alterations of Plant
Communities
Component
Direction
Magnitude
Geographic
Extent
Duration
Reversibility
Frequency
Environmental
Consequence
losses to plant communities
forested vegetation
types
negative
moderate
local
medium-
term
reversible
medium
low
wetlands
negative
moderate to
high
local to
regional
long-term
irreversible
medium to
high
moderate
