Environmental Assessment
Volume C-4.3
Slurry Pipeline
Fish and Aquatic Resources
Ambatovy Project
135
January 2006
Table 4.3-7 Potential Effects and Residual Impacts for Aquatic Habitat
Project Period
Potential Effects
Mitigation
Residual Impacts
construction
displacement and disturbance of
critical riparian and instream aquatic
habitats
effects on downstream water quality
(TSS) and habitat loss
use of aerial crossings,
water diversion techniques
or trenchless methods at all
critical / endemic habitat
water management,
including silt traps,
sedimentation ponds
minimize RoW clearing and
grading
erosion control
low magnitude / short-term
physical disturbance during
pipeline construction
high magnitude /short-term
disturbance from water quality
/ TSS changes during both
pipeline, RoW and road
construction
low magnitude / short-term
physical disturbance during
road and infrastructure
construction
low magnitude /long-term loss
from footprint and effects of
bridges, culverts, etc.
operation
potential alteration of downstream
watercourse habitats for as a result
of hydraulic and water quality
changes (increased TSS from
erosion) , spills or pipeline breaks
water management plan
revegetation
erosion and sediment
guidelines
spill response plan
low magnitude / medium-term
modification of habitats
closure
existing changes in the landscape
continued water
management; erosion
control
on-site reclamation and
habitat enhancement
low magnitude / long-term
modification of crossing
location habitats
The status of aquatic habitat in the pipeline area is moderately well understood,
but the level of baseline information (ground surveys at 15 of 99 potential
watercourse crossings) is low-moderate. This is because, surveys have shown
that it is difficult to generalize results to other streams, even though
representative size classes of stream were visited. Construction mitigation will
however be used, which means that the prediction confidence for impact ratings
for habitats within the slurry pipeline area is medium.
An overall residual impact classification is presented in Table 4.3-8; the overall
environmental consequence scores were based on the screening system described
in Volume A, Section 7.
