Environmental As
Mine
sessment
Volume B-5.4
Human and Ecological Health
Ambatovy Project
382
January 2006
Table 5.4-6 Assessment Criteria for Evaluation of Effects on Aquatic Life
Resource
Direction
(a)
Magnitude
(b)
Geographic
Extent
(c)
Duration
(d)
Reversibility
(e)
Frequency
(f)
aquatic life
health
positive
(beneficial
in nature),
negative
(adverse in
nature)or
neutral
for the
measurement
endpoints
negligible
HQ≤1
or no change from
Baseline Case
Low and likely to
be negligible
:
HQ>1 and ≤10
Potentially
elevated
: HQ>10
local
: effect
restricted to the LSA
regional
: effect
extends beyond the
LSA into the RSA
beyond
regional
:
effect extends
beyond the RSA
short-term
:
construction
medium-
term
:
operation
long-term
:
post-closure
reversible
or
irreversible
low
: occurs
once
medium
:
occurs
intermittently
high
: occurs
continuously
(a)
Direction: positive (beneficial to, or protective of health) or negative (adverse towards health).
(b)
Magnitude: degree of change to analysis endpoint: potential incremental hazard quotient (HQ).
(c)
Geographic Extent: area affected by the impact.
(d)
Duration: length of time over which the environmental effect occurs. Considers a three-year construction period and a 27-
year operations period.
(e)
Reversibility: effect on the resource (or resource capability) can or cannot be reversed.
(f)
Frequency: how often the environmental effect occurs.
Results
Water Quality
Although aluminum, iron, copper, lead and manganese were considered
chemicals of potential concern in the baseline risk assessment (Section 5.4.3
Baseline Summary) they were not assessed further because predicted
concentrations are similar to the baseline conditions and hence no incremental
risk for aquatic life is expected for these chemicals.
Water quality parameters which were conservatively predicted to change due to
the operation of the mine (Section 3.9, this volume) were screened against South
African Guidelines for Aquatic Ecosystems (DWAF 1996). Alternative
references were used for sulphate (100 mg/L) and barium (1 mg/L) which are not
listed in the South African document (Recommended Guideline for Freshwater
Aquatic Life by Province of British Columbia, 2001). These screening criteria
suggested fluoride, sulphate, arsenic, barium and zinc were not chemicals of
concern and therefore did not warrant further consideration.
Sodium, chromium, molybdenum, thallium and selenium, however, were
retained for further analysis because no screening guideline values were available
(for sodium, molybdenum and thallium) and because concentrations of selenium
exceeded guidelines. The calculated hazard quotients (HQs) for each type of
organism are presented in the Table 5.4-7. The HQs for all chemicals were
considered negligible. Therefore incremental risk to aquatic life due to mine
operations is considered unlikely.
