Environmental Assessment
Volume E-3.10
Tailings Facility
Water Quality
Ambatovy Project
119
January 2006
3.10
WATER QUALITY
3.10.1 Introduction
This section presents the Environmental Assessment (EA) for the effects of the
tailings facility on water and sediment quality, as per the Ambatovy Project (the
project) Terms of Reference described in Volume H, Appendix 1.
The project will include the construction, operation and reclamation of a facility
to hold the tailings material after it has been treated at the process plant.
Groundwater originating from the tailings facility area will be affected by the
tailings material and has the potential to change surface water quality
downstream of the tailings facility. In addition, development of the tailings
facility will involve the collection and diversion of surface runoff in the upper
basins of the affected watersheds. As a result, flows in the downstream rivers of
the tailings facility will decrease, reducing the dilution (assimilation) capacity of
these receiving watercourses.
Groundwater seepages from the tailings facility can also cause changes in
sediment quality. Increases in the concentration of substances in the water
column may enhance adsorption into the 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.
Water and sediment quality information has been compiled to characterize
baseline conditions in the tailings area (Volume I, Appendix 9.1). The available
baseline information is used in the following sections to predict and evaluate
potential effects of the project on water and sediment quality.
3.10.2 Study Area
The Local Study Area (LSA) for water quality is the same as the hydrology study
area for both the tailings facility and process plant, as presented in Volume A,
Section 7, Figure 7.2-3. The area includes the likely spatial extent of tailings
facility development and effects on water and sediment quality. The LSA for the
tailings area includes the subcatchments downgradient of the tailings facility,
which drain three tributaries and a reach of the Ambolona River. These features
are shown on Volume A, Section, 7, Figure 7.2-3.
