Summary
above the Malagasy water quality standards. These parameters require
further dilution on disposal into the marine environment in order to
reduce possible negative impacts.
According to the modelling, effluent components will be diluted to within
water quality limits by the time they reach the water surface. However,
the discharge of effluent may result in a change in species composition
and abundance in the immediate sea bed area (500 – 1000 m) around
the effluent disposal site. This will prevail throughout the operational
phase of the mine until natural recovery of the benthic biota occurs once
the mine is decommissioned. However, the impact occurs within an area
of low conservation importance, which already experiences high levels of
turbidity. Therefore, the overall environmental consequence has been
predicted to be low.
Reef near Toamasina
Although increases in turbidity are generally non-toxic, they can have
both direct and indirect impacts on the marine environment. Specific
consideration was given to the corals found at Nosy Faho, south of the
proposed outfall. The modelling indicates that the outfall plume could
move in the direction of Nosy Faho, but due to dilution, the TSS would be
similar to present conditions and the impact would be low around this
reef.
Predicted manganese concentrations derived from conservative
modelling indicate that guideline levels will be achieved through rapid
dilution in the outfall area. Manganese is not predicted to pose a risk to
ecological health.
A local change in sea bed biota near the pipe outfall may result in a
moderate impact on the local fishery right by the outfall. The fisheries
sometimes operating within the area are the small scale commercial
operators and artisanal fishers who occasionally venture out to sea from
the Ivondro estuary. The line fishery operates on deeper reefs, none of
which are found around the proposed outfall location.
Socioeconomics
The human and ecological health assessment evaluated the potential for
adverse effects to health associated with seepage from the tailings
facility. Human exposure to drinking water and eating fish and aquatic
life exposure to water and sediment were evaluated as well as potential
effects on changes in livelihood resources due to impacts on surface
water quality. With the proposed mitigation in place, potential effects
were rated as low to negligible for people, aquatic life, livestock and
produce.
Human health
For the population between the tailings facility and the plant site, the
impact analysis is similar as has been summarized for the plant area,
with some differences of emphasis as noted below. Differences are
Socioeconomics
January 2006
Ambatovy Project — 40
