Environmental Assessment
Volume C-3.2
Slurry Pipeline
Soils
Ambatovy Project
30
January 2006
Table 3.2-4 Disturbance of Soil Types Along the Slurry Pipeline
Soil Type
Length of Slurry
Pipeline (km)
Area
(ha)
Percent of LSA
(%)
high to moderate erosion risk (clearing/tavy
vegetation type)
170
800
89
low erosion risk (remaining vegetation types)
25
96
11
Total
195
896
100
3.2.3.5 Residual Impact Analysis
The environmental consequence of the slurry pipeline on soils is rated as
moderate during construction, low during operation and low following closure
(Table 3.2-5).
Slurry pipeline construction will result in a short-term disturbance of the pipeline
RoW. The erosion risk of all soils will increase substantially with the removal of
vegetation, particularly the 96 ha with substantial vegetation cover (Table 3.2-4).
Due to the relatively short construction time period, the environmental
consequence was rated as moderate.
During pipeline operation, the surface soil erosion risk will decrease substantially
once vegetation re-establishes and slopes are stabilized. Many mitigations will
be implemented to control erosion (Section 3.2.4.1). The high intensity of
precipitation in the region makes erosion events highly likely.
The environmental consequence was rated as low following closure since natural
erosion rates are expected once a stable vegetation cover is established (see
Volume C, Section 6).
Table 3.2-5 Residual Impact Classification for Soils
Phase
Direction Magnitude Geographic
Extent
Duration Reversibility Frequency
Environmental
Consequence
Key Question ST-1What Effect Will the Slurry Pipeline Have On Soils?
construction negative
high
local
short-
term
no
low
moderate
operations
negative
moderate
local
medium-
term
yes
low
low
closure
negative
low
local
long-term
yes
low
low
