Environmental Assessment
Volume B-3.9
Mine
Water Quality
Ambatovy Project
115
January 2006
3.9
WATER QUALITY
3.9.1
Introduction
This section presents the Environmental Assessment (EA) for the effects of the
mine on water and sediment quality as per the Ambatovy Project (the project)
Terms of Reference, which is described in Volume H, Appendix 1.
The project will include the development of a nickel laterite mine for two ore
bodies, referred to as the Ambatovy and Analamay areas. Development of the
mine will involve varying degrees of land disturbance, such as removal of
vegetation, excavation and ground compaction. The mine will also include the
construction of roads, buildings, parking and storage areas, waste dumps, and an
ore preparation facility, which will include the preparation plant and water
holding pond or tank. These disturbances will result in increased rates of runoff
from the area until reclamation and re-vegetation activities are complete. The
increased runoff will likely increase erosion and transport additional sediment
into downstream watercourses. Changes in suspended sediment concentration
due to potential increases in erosion are addressed in Section 3.8 of this volume
(Hydrology).
During operations, the water quality of runoff that originates from different land
types within the mine area may be different than the water quality of runoff
during baseline conditions. All runoff from the site will be controlled. The
majority of the runoff from the mine area will be routed to collection and
clarification ponds and then released to downstream watercourses and water
bodies. These releases have the potential to affect the water quality of the
receiving downstream waters. Any runoff that is not routed to the ponds will be
diverted to the ore preparation plant or slurry pipeline that transports mined ore
to the process plant, as described in Volumes C (slurry pipeline) and D (process
plant).
The mine development and operations can also cause changes in sediment
quality. Increases in the concentration of substances (e.g., metals and organics)
in the water column may enhance adsorption of these substances to sediment and
result in changes in sediment quality. Furthermore, if unmitigated, increased
erosion could contribute to changes in substance concentrations in bottom
sediments of receiving watercourses and water bodies.
