Environmental Assessment
Volume E-3.3
Tailings Facility
Soils
Ambatovy Project
37
January 2006
Table 3.3-4 Residual Impact Classification for Soils
Phase
Direction Magnitude
Geographic
Extent
Duration
Reversibility Frequency
Environmental
Consequence
Key Question ST-1What Effect Will the Tailings Facility Have On Soils?
construction negative
high
local
long-term
no
low
high
operations
negative
high
local
long-term
no
low
high
closure
negative
low
local
long-term
yes
low
low
3.3.3.6 Prediction Confidence
The soil impact classification relies heavily on the planned reclamation program
to establish a productive soil on the tailings material and implement successful
erosion control methods. There are uncertainties regarding the reclamation of the
tailings, given very high local rainfall. As noted above, there are uncertainties as
to how quickly the tailings will harden at closure, to allow re-vegetation.
Planned reclamation research will address these issues.
3.3.3.7 Monitoring
The proponent will implement reclamation monitoring programs to ensure
mitigation processes are successful and adjust if necessary. The tailings
reclamation monitoring plan will consist of:
•
ensuring that environmental protection measures are being followed
during tailings construction, operations and closure;
•
ensuring tailings dike stability;
•
measuring vegetation performance; and
•
documentation of the monitoring results.
3.3.4
Conclusions
Following mitigation, the tailings will have a high environmental consequence
for soils during the construction and operations phase due to the long-term loss of
productive land use. There will be a low environmental consequence following
closure and reclamation. The main issues are the loss of productive land and the
increase in erosion risk of the fine-textured soils on the tailings dikes. The
potential impact to soils has implications for vegetation, hydrology and
particularly water quality, where there is a likelihood of increased sediment
runoff. These issues are addressed in other sections of the EA.
