Environmental Assessment
Volume B-3.9
Mine
Water Quality
Ambatovy Project
118
January 2006
have been derived, due to local climatic, geological and hydrogeochemical
characteristics and the adaptation of site-specific aquatic species.
3.9.3.2 Sediment Quality
Stream bed sediment in the mine area ranged from predominantly fines to
predominantly coarse material. Differences in the physical characteristics of
sediments are manifested as differences in key chemical characteristics of
sediment, including organic carbon, nutrients and metals. However, due to the
limited sediment quality sampling undertaken so far, it is not possible to identify
clear spatial trends in sediment characteristics within the mine area.
Madagascar does not have sediment quality guidelines. In the absence of
national sediment quality guidelines, results of sediment quality sampling at the
site were compared to international guidelines from Canada (CCME 2003) and
the US (US National Oceanographic and Atmospheric Association 1999).
Because guidelines from other jurisdictions do not take into account local
ecological conditions, guideline exceedances should be treated with caution.
These international sediment quality guidelines are available only for a few
metals, including arsenic, cadmium, copper, lead, mercury, nickel and zinc. Of
the metals with sediment guidelines, only two, copper and nickel, were above the
corresponding international guidelines.
Additional details concerning baseline conditions are provided in Volume I,
Section 9.1.
3.9.4
Issue Scoping
Surface water concerns of stakeholders and regulators are focused on potential
changes for water users and ecological processes (Volume A, Section 6).
Downstream water users and aquatic life may be adversely affected by changes
in water and sediment quality associated with construction, operation, and
closure activities of the project. In the watersheds surrounding the project, the
major water uses include domestic, agricultural irrigation (mainly rice paddies)
and ecological sustenance.
The following aspects of the project in the mine area could potentially affect
water and sediment quality of nearby surface watercourses and water bodies:
•
site preparation and clearing;
•
air emissions from ore preparation plant, mine equipment and vehicles;
