Environmental Assessment
Volume B-3.3
Mine
Soils
Ambatovy Project
39
January 2006
3.3.3.5 Results
A total of 1,734 ha of soils will be disturbed by the mine over the life of the
project (Table 3.3-3). The majority of disturbed soils will be red/yellow ferrilitic
soils (731 ha, 42 % of total). The second most common disturbance type is the
armoured ferricrete soils (474 ha, 27% of total). Ferricrete soils are associated
with azonal vegetation and once disturbed the dense surface horizon cannot be
reclaimed following mine closure. Therefore, there will be a permanent loss of
474 ha of these unique soils following mining (Table 3.3-3). However, other
soils will form with the aid of reclamation amendments. When reclamation is
completed following closure, there will be no overall net loss of soils due to the
mine, although different soils will predominate.
Table 3.3-3 Disturbance of Soil Types in the Mine Area
Soil Type
Area
(ha)
Percent of LSA
(%)
armoured ferricrete
474
27
organic
13
1
pisolite
516
30
red/yellow ferrilitic
731
42
total
1,734
100
3.3.3.6 Impact Analysis
Residual Impacts
The environmental consequence of the mine on soils is rated as moderate during
construction, high during operation and low following closure (Table 3.3-4).
Mine construction will result in a gradual disturbance of the mine pits as mining
progresses. Once mine construction disturbs the dense surface horizons of
ferricrete soils, these soils conditions will not be replicated following
reclamation. Also, the erosion risk of all soils will increase substantially with the
removal of vegetation. Due to the relatively short construction time period, the
environmental consequence was rated as moderate.
During mine operation, the surface soil erosion risk will increase substantially
due to the long length of time that soils will be without vegetation cover. While
many mitigations will be implemented to control erosion (Section 3.3.3.4), the
high intensity of precipitation in the area makes erosion events highly likely. The
environmental consequence for soils is high during operations.
