Environmental Assessment
Volume C-3.2
Slurry Pipeline
Soils
Ambatovy Project
24
January 2006
Table 3.2-1 Summary of Pipeline Soil Characteristics
Slope Position
Soil Type
Soil Characteristics
summit (crest)
ferrilitic soils – typical
blocky structure (Oxisols)
soil has a “good” blocky structure, soil is chemically rich due to
enrichment by bases and minerals (mica); soil cohesion is weak to
medium
mid slope
strongly altered or
changed ferrilitic soils
(Ultisols)
soil horizon with weak cohesion low and weak structure; soil
aggregates are porous; primary minerals are more or less altered
(disappeared)
base of slope
(depressions)
poorly developed
hydromorphic soils
(Histosols)
soils are more or less rich in altered minerals; horizons have formed
from valley alluvium; soils are sandy or silty with low clay content;
soils have concretions
Additional details concerning baseline conditions are provided in Volume I, Appendix 3.1.
3.2.3
Impact Assesssment
3.2.3.1 Issue Scoping
The list of issues from the Terms of Reference (Volume H, Appendix 1) and the
public consultation program (Volume A, Section 6) were reviewed to focus the
soil assessment on key issues and group the issues into common themes.
As part of this process, an interaction matrix was used to evaluate all possible
slurry pipeline impacts on soil resources (Table 3.2-2). The interactions were
rated to highlight the key issues and to help focus the assessment.
Only those activities rated moderate or high were analyzed in detail in the
assessment.
Table 3.2-2 Project Interaction Matrix
Project Activities or Facilities
Soil
(a)
Issue
Comments
construction phase
vegetation clearing
M to H
increase in wind and water
erosion risk; soil compaction
from equipment
impact depends on length of time
soil exposed and timing of
construction (e.g., dry season)
topsoil removal
H
increase in wind and water
erosion risk; loss of soil
nutrients, soil compaction
final impact depends on whether
topsoil is salvaged and stored
overburden removal
M to H
wind and water erosion; soil
compaction from equipment
impact depends on length of time
soil exposed
potential spills
L to M
contamination from spills
impact depends on clean spill
response
reclamation and closure phase
reclamation
P
reclamation of disturbed areas
positive effect
(a)
Interaction Ratings: N - Negligible; L - Low; M - Moderate; H - High; and P - Positive.
