Environmental Assessment
Volume C-3.7
Slurry Pipeline
Water Quality
Ambatovy Project
61
January 2006
3.7
WATER QUALITY
3.7.1
Introduction
This section presents the Environmental Assessment (EA) for the effects of the
slurry pipeline on sediment and water quality as per the Ambatovy Project Terms
of Reference, which is described in Volume H, Appendix 1.
Construction of the slurry pipeline will involve clearing and excavation along the
pipeline right-of-way as well as disturbance to the streambed at watercourse
crossing locations. Channel disturbance during construction may affect water
and sediment quality in downstream reaches. Water withdrawal and disposal will
also be required for hydrostatic testing of the pipeline. The disposal of
hydrostatic testing waters may affect water and sediment quality.
Field water quality data were measured along the pipeline route (Volume I,
Appendix 9.1) and is summarized briefly in Section 3.7.3 below. The available
baseline water quality is summarized in this section to evaluate potential effects
of the Ambatovy Project (the project) on water quality.
3.7.2
Study Area
The local study area (LSA) for the slurry pipeline is shown in Volume A,
Figure 7.2-2 and is the same as the LSA for hydrology assessment. The study
area includes a 1 km buffer on both sides of the route, along the length of the
pipeline corridor.
3.7.3
Baseline Summary
Field measurements were taken at watercourse stations along the proposed slurry
pipeline route. The watercourses were slightly acidic to slightly alkaline with pH
ranging from 6.2 to 7.6. Temperature values ranged from 17.5 to 27°C and
dissolved oxygen results were generally at or below saturation.
Based on the Madagascar classification system for water quality, five
watercourses were classified as Class A, which indicates that these watercourses
are suitable for multiple uses, including swimming. Seven of the watercourses
were classified as Class B, which indicates that although the water is suitable for
non-contact recreation, it may not be suitable for swimming.
