Overburden is rock that must be
moved aside to gain access to ore that is mined and processed to
recover metals for commercial purposes. PT Freeport Indonesia
handles overburden under a comprehensive Overburden Management
Plan approved by the Government of Indonesia. Many metals occur
in nature as sulphide minerals. When ore is mined and overburden
containing sulphides is left exposed to the elements, the action
of water, oxygen and naturally occurring bacteria has the
potential to create
sulfuric acid. This acidic water can
dissolve metals contained in overburden rock and cause adverse
environmental impacts in water drainage systems if not properly
managed. This process is known as acid rock drainage (ARD).
PT Freeport Indonesia manages and monitors acid rock drainage
from its operations. Independent audits of PT Freeport
Indonesia’s environmental management system concluded that our
overburden management programs are “well integrated” and
“consistent with international practice.” Under the
Government-approved overburden management plan, PT Freeport
Indonesia places overburden in managed areas around the Grasberg
open pit. PT Freeport Indonesia’s acid rock drainage mitigation
plans provide for capture and treatment of the existing acid
rock drainage, in conjunction with limestone blending and
limestone capping of existing overburden placement areas to
manage future acid rock drainage generation.
PT Freeport Indonesia’s
long-term environmental monitoring program (LTEMP) evaluates
potential impacts of our operations by routinely measuring water
quality, biology, hydrology, sediments, air quality and
meteorology in our area of operations. In 2006, the overall
monitoring program encompassed the collection of nearly 7,000
environmental samples and the completion of over 53,000 separate
analyses on these samples, including aquatic biology, aquatic
tissue, plant tissue, mine water, surface water, ground water,
sanitary wastewater, river sediments and tailings. The program
ensures that we have the scientific information necessary to
make management decisions about our operations so that we can
minimize and mitigate environmental impacts.
PT Freeport Indonesia does not use mercury or cyanide in its
processes, relying instead on a flotation process that
physically separates the copper- and gold-bearing minerals from
the ore. Comprehensive monitoring conducted over many years
continues to show there is no significant elevated level of
mercury or arsenic in the water, sediment, fish or plants from
our operations area relative to background samples from the east
and west of our project. |
|
LONG-TERM
ENVIRONMENTAL MONITORING PROGRAM |
|
|
However, the recent high price
of gold has enabled the profitable recovery of gold from the
tailings stream by panners not licensed by the Government of
Indonesia (GOI), who have moved into the area by the thousands,
straining resources (particularly medical resources) and
pressuring the local population. The unlicensed panners do not
participate in traditional mining as their activity is recent
and the panners are not native to the area. PT Freeport
Indonesia cooperates with the government in attempting to
control this situation and remove these panners, and this has
precipitated occasional confrontations, which in one case
resulted in a four-day shutdown of production in 2006. As a
result of this activity, we have developed a concern about the
possible use of mercury in refining this illegally taken gold.
To date, our environmental monitoring programs have not detected
mercury in the area. At our request, the United Nations
Industrial Development Organization/Global Mercury Project
inspected the area and confirmed that mercury was not yet being
used in the area.
In 2006, PT Freeport Indonesia monitored water
quality at over 200 locations throughout the project area,
collected nearly 6,000 water samples and conducted nearly 45,000
water quality analyses. We monitored more than 100 sampling
locations for nekton, benthos, plankton and mangrove
invertebrates in the aquatic biology program. As noted above,
data from this sampling continue to show that the estuary
downstream of the tailings deposition area is a functioning
ecosystem, based on both the number of species and the number of
specimens collected of nektonic, or free-swimming, organisms
such as fish, shrimp and mangrove aquatic fauna. |
|
|
Between 1999 and 2006, over 6,000 samples of aquatic fauna were
collected and a total of over 34,000 analyses conducted on them.
The monitoring of benthos, or bottom-dwelling organisms,
continued in 2006 at 16 sites in the estuaries and 40 sites in
the Arafura Sea. Studies during our approved 300K AMDAL
identified these organisms as being at risk from sedimentation.
The results of this monitoring indicated that tailings sites
generally have high densities of very small polychaetes, or
marine worms, which are pioneer species to disturbed areas.
Benthos diversity is now increasing in the Minajerwi estuary, an
area that received tailings prior to design and construction of
the tailings deposition area, indicating no long-term impacts
once mining operations are completed. The monitoring also
indicates no impact of tailings on the marine benthos in the
Arafura Sea outside of the tailings management area.
As part of routine environmental audits by the Government of
Indonesia regulators, Sarpedal (the government’s environmental
laboratory) annually samples water, sediment, fish, ambient air
and stack emissions. Results generally confirm PT Freeport
Indonesia’s results routinely reported in Environmental
Management Plan and Environmental Monitoring Plan reports to the
government. |
|
 |
The Timika Environmental Labratory is an important part
of Freeport Indonesia’s Long-Term Environmental
Monitoring Plan. |
|
|
| |
|
