Environmental Assessment
Volume E-3.7
Tailings Facility
Hydrogeology
Ambatovy Project
51
January 2006
Table 3.7-1 Groundwater Quality in the Area of the Proposed Tailings Facility
Constituent
Unit
WHO Drinking
Water Guidelines
Borehole
HG1
Borehole
HG2
Borehole
HG3
Borehole
HG5
Borehole
HG6
pH value @ 190
°
C
pH
N/A
6.1
7.6
6.4
6.8
7.6
conductivity @ 25
°
C
mg/l
N/A
15.2
24.9
11.8
21.8
30.6
total dissolved solids
mS/m
0-1000
128
280
154
222
282
calcium as Ca
mg/l
N/A
7.4
19.2
4.7
9.7
24
magnesium as Mg
mg/l
N/A
2.1
13.8
<0.1
8.6
14.9
sodium as Na
mg/l
0-200
13
11.7
12.9
22
17.6
total alkalinity as CaCO
3
mg/l
N/A
34
108
42
82
126
bicarbonate as HCO
3
mg/l
N/A
41
132
51
100
154
carbonate as CO
3
mg/l
N/A
Nil
Nil
Nil
Nil
Nil
chloride as Cl
mg/l
0-250
23
11.2
13.3
13.3
10.2
sulphate as SO
4
mg/l
0-250
1.9
2.9
1.4
3.5
3.8
nitrate as NO
3
mg/l
0-50
0.2
<0.1
<0.1
<0.1
<0.1
nitrite as NO
2
mg/l
0-0.02
<0.1
<0.1
<0.1
<0.1
<0.1
fluoride as F
mg/l
0-1.5
-
-
-
<0.1
<0.1
arsenic as As
mg/l
0-0.01
<0.01
<0.01
<0.01
<0.01
<0.01
aluminium as Al
mg/l
0-0.2
<0.01
<0.01
0.78
0.18
0.03
nickel as Ni
mg/l
0-0.02
<0.003
<0.003
<0.003
<0.003
<0.003
manganese as Mn
mg/l
0-0.4
0.11
0.03
0.02
0.13
0.27
iron as Fe
mg/l
0-0.3
<0.001
<0.001
0.08
<0.001
<0.001
vanadium as V
mg/l
N/A
<0.002
<0.002
0.002
<0.002
<0.002
zinc as Zn
mg/l
0-3
1.13
0.22
8.1
9.1
2.10
lead as Pb
mg/l
0-0.01
<0.01
<0.01
<0.01
<0.01
<0.01
cobalt as Co
mg/l
N/A
<0.001
<0.001
<0.001
<0.001
<0.001
copper as Cu
mg/l
0-2
<0.002
<0.002
<0.002
<0.002
<0.002
chromium as Cr
mg/l
0-0.05
<0.003
<0.003
<0.003
<0.003
<0.003
barium as Ba
mg/l
0-0.7
0.07
0.012
0.016
<0.001
0.02
mercury as Hg
mg/l
0-0.001
<0.001
<0.001
<0.001
<0.001
<0.001
silica as SiO
2
mg/l
N/A
26
73
63
47
75
Highlighted values: exceed World Health Organization drinking water guidelines.
The groundwater quality of the area is in general suitable for domestic use
(including human intake). Elevated metal concentrations (compared to WHO
standards) have been analysed for samples from boreholes HG3 and HG5. Metals
that exceed WHO standards are:
•
Aluminium (HG3)
- often associated with particulate matter or organic
complexes of high relative molecular mass. Aluminium occurs in
groundwater as a result of leaching from soil and rock material. Biotitic
associated with the gneiss and schist also contains aluminium.
