Environmental Assessment
Volume E-1
Tailings Facility
Alternatives Considered
Ambatovy Project
8
January 2006
1.3
PREFERRED OPTION
During the site investigation of the TA-10 and 11 valleys in May 2004, the
potential socioeconomic impacts from using these two valleys was reviewed in
more detail. As a result of these investigations, Option 4 was developed, which
minimizes impacts to the downstream or eastern portions of TA-10 and 11 where
the valleys are more heavily populated and cultivated. Option 4 is similar to
Option 3 for the initial phase but different in later years. To minimize social
impacts in the eastern or downstream portions of TA-10 and 11, the upper part of
a valley west and south of TA-10 was chosen for Phase 2 tailings deposition
while the western portion of TA-10 was selected for a water basin (Figure 1-3).
During Phase 3, tailings would be placed in the west portion of TA-10 with a
new water basin being placed to the east within TA-10. A more detailed
description of each phase is provided in the next section.
In terms of economics, Knight Piésold has indicated that Option 1 has the lowest
estimated construction cost, followed by Option 2, 3, and lastly, Option 4.
However, it has been realized that reduced construction cost does not compensate
for the upfront socioeconomic impact and the cost of relocation of the population
within the valleys. There is a relatively large population in the eastern end of the
valleys, and this would have an adverse effect on project cost and schedule, as
well as a high socioeconomic impact.
The first phase of Option 3 and Option 4 would be built in an area of lower
population density than Option 1. However, the higher population density area
would eventually be developed. Option 4 does not use the lower elevation areas
of the valleys and, therefore, avoids the areas of highest population density. For
this reason, Option 4 was selected as the preferred option.
