Environmental Engineering Reference
In-Depth Information
●
Might natural upstream-to-downstream changes account for monitoring results? As
one example benthic macro-invertebrate results might be explained by natural shifts in
macro-invertebrate community composition from headwaters to mouth.
●
Does weather appear to inl uence monitoring results? For example, do problem levels
coincide with intense rainstorms? Might elevated water temperature levels be caused
by unusually hot weather?
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Does the presence of specii c sources explain results? As one example, can increased
water turbidity be attributed to logging activities? Can mercury content in sediment
be related to small-scale gold mining?
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Do changes in one parameter appear to explain or to relate to changes in another? As
one example, could low dissolved oxygen be explained by high temperature? Do prob-
lem levels coincide with rising l ow?
●
Do visual observations support i ndings? For example, observed land clearing upstream
of the monitoring location may explain high turbidity.
●
For multiple years of data, are there overall trends?
Sometimes, monitoring results may be simply explained by the way samples were col-
lected and analyzed. Flaws in i eld and/or laboratory techniques do occur. For example,
high concentrations at one location may be the result of cross contamination, due to a sam-
pling error, or simply the result of erroneous laboratory analysis. Field equipment should
CASE 8.10
Sometimes Conclusions are Controversial
Newmont Mining Corporation's 80%-owned subsidiary, PT
Newmont Minahasa Raya (PTNMR), operated the Minahasa
Gold Mine at Mesel in North Sulawesi, Indonesia from 1996
to August 2004. PTNMR was authorized by the Indonesian
government to use submarine placement of tailings (tail-
ings are fi nely ground rock from which gold has been
recovered). The tailings were placed on the seabed at a
depth of 82 metres via a pipeline that rested on the sea-
bed. The pipeline extended 900 metres from the coast with
the outfall well outside 'Buyat Bay'. As known and analyzed
in the environmental impact assessment completed prior
to operations, the Mesel ore contained small amounts
of naturally occurring, insoluble mercury and arsenic
compounds. Roasting of the ore prior to gold extraction
removed the mercury, which was recovered and sent to a
government approved hazardous waste storage site. Arsenic
remained in the tailings as insoluble compounds. In July
2004, shortly before the eight year project operations were
scheduled to cease due to completion of the mine, non-
governmental organizations (NGOs) instigated a campaign
alleging that PTNMR's use of submarine tailings placement
had polluted Buyat Bay with mercury and arsenic causing
adverse health effects to area residents. In subsequent
months, the Government of Indonesia initiated civil and
Sea Garden Standard 6
g/l
6
5.5
5
Standard Applicable to Mining 5
g/l
4.5
PTNMR Monitoring
(1996-2004)
4
Ministry of
Environment Survey
3.5
3
Police Replicate
Samples
2.5
North Sulawesi
Independent Team
2
CSIRO Survey
1.5
2004 Seawater Standard 1
g/l
WHO/Minamata
Institute
1
0.5
Government
Integrated Team
0
criminal proceedings against PTNMR and its senior manage-
ment. This conclusion was based on samples collected by
the Indonesian police and tested in government laboratory.
Subsequently the company and government regulators
carried out additional sampling and analyses, the results
of which failed to support the results obtained in the
police investigation. In fact these results indicated that
mercury and arsenic concentrations in the sea water were
well within the range of natural concentrations for these
elements. Despite such fi ndings from respected independ-
ent authorities such as the CSIRO from Australia and the
Minimata Institute from Japan, the case against PTNMR
continued until in 2007, the mining company and its
management were eventually acquitted of the charges.
Source:
Newmont's letter to the stakeholders, 31 May 2006
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