Summary
Madagascar is a developing field and revegetation trials will be
established to increase this knowledge base and develop pragmatic
restoration solutions. The lessons learned from these trials will also be
made available to other restoration efforts planned by other
organizations within the Ankeniheny–Zahamena Corridor.
Impacts to faunal populations as a result of habitat fragmentation are
predicted to be low because most of the route was sited along pre-
existing disturbance and the pipeline will be buried. Construction will
create temporary barriers to movement (e.g., roads, construction activity)
for fauna in environmentally sensitive forest areas near the mine.
Connectivity will be restored once the pipeline is buried and the route
reclaimed to forest on the right-of-way in these sensitive areas. In some
areas, roads will be left in place as part of regional planning, so barriers
to movement will remain. However, the majority of these roads will be in
areas of existing disturbance and higher population density. No
maintenance road will be constructed alongside the sections of pipeline
to be reclaimed to primary forest near the mine and in the Ankeniheny–
Zahamena Corridor.
Minimization of impacts to aquatic and riverside resources will come
from mitigation applied at stream crossings. Construction of the slurry
pipeline will involve about 100 watercourse crossings of a variety of
sizes. Initial assessments of the crossings have been conducted to
assist in pipeline routing. Just prior to construction, an environmental
team will conduct a further field survey of the crossing locations and
identify any with high sensitivities with respect to aquatic and riverside
resources. Where feasible, the pipeline route will be adjusted through
design or minor reroute to avoid or minimize impacts on the sensitive
areas. The majority of watercourse crossings will be buried and will
involve excavating across the channel, laying the pipe and backfilling the
trench. Where possible, water will be diverted to one side of the stream
to enable a relatively dry work space on the opposite side. Construction
of crossings will typically be conducted during low flow conditions to
minimize water depths and the amount of suspended solids generated
and transported to downstream reaches. The effects on suspended
solids levels are expected to be high during construction, but to last only
a short time, on the order of hours for small streams and up to a few
days for very large streams. No effects on sediment levels are expected
in the streams during operation or post-closure since revegetation and
erosion controls will have been applied and stream banks will be
stabilized.
Aquatic resources
Aquatic organisms survey
Endemic fish species were mainly associated with the presence of
natural forest stream habitat (40% of sample sites). Assuming open cut
installation of the pipeline, effects will be primarily short-term disturbance
of riparian and instream habitat and limited to the construction period.
January 2006
Ambatovy Project — 24
