Environmental Assessment
Volume E-3.10
Tailings Facility
Water Quality
Ambatovy Project
139
January 2006
However, an increase in concentration of 0.006 mg/kg is considered to be small
relative to the CCME ISQG of 37.3 mg/kg.
Table 3.10-5 Predicted Maximum Concentration in Bottom Sediment in the
Tailings Area Versus Baseline and Guideline Values
Operations
Post-closure
Results Above
Canadian Sediment
Guidelines
Results Above
Canadian Sediment
Guidelines
Parameter
Results Above
Baseline Sediment
Concentration
ISQG
(a)
PEL
(b)
Results Above
Baseline Sediment
Concentration
ISQG
(a)
PEL
(b)
aluminum
-
-
arsenic
-
-
barium
-
-
chromium
√
-
-
√
-
-
cobalt
-
-
copper
-
-
lead
√
-
-
√
-
-
manganese
-
-
mercury
√
-
-
√
-
-
nickel
-
-
vanadium
-
-
zinc
√
NG
NG
-
iron
-
-
(a)
Probable Effect Level (CCME 2003).
(b)
Interim Sediment Quality Guideline (CCME 2003).
-
Not above baseline (less 10% difference between baseline and maximum predicted concentration) or guideline
value.
√
Project-related changes in water quality concentrations are above baseline value by 10% or more.
Blank cell Not compared to guidelines when projected-related activities results in less than 10% difference in maximum
predicted concentration compared to baseline value.
NG
No applicable guideline.
Note:
Because baseline concentrations were not available for chromium, it was assumed that predicted maximum
concentrations were above baseline concentrations. If a 0.006 mg/kg increase would have caused
concentrations to increase above the ISQG, than this would have resulted in an increase of less than 10% from
baseline.
3.10.5.5 Impact Analysis
Prediction Confidence
The main potential sources of uncertainties in the water and sediment quality
assessment include surface and groundwater flows, baseline water quality,
seepage quality and runoff water quality. The prediction confidence of the
surface water flows was medium for average flows and low for dry season flows,
as discussed in Volume E, Section 3.8. The baseline status of surface water in
