Pascua-Lama will operate based on industry-leading environmental systems and safeguards. Environmental approval for the project includes controls for the protection of the three ice bodies in the vicinity of the project as well as water resources.
These safeguards, particularly the project’s multiple-barrier water management system, were designed in consultation with downstream water users. A dedicated team of environmental and engineering professionals will manage the project, with active involvement and monitoring by independent auditors, government regulators and communities.
“The water coming out of the mountains in the project area is not crystal clear,” said Bruce Mack, Pascua-Lama’s environmental manager. “It is naturally acidic. Yet as it travels further downstream into the river systems, it becomes diluted and acceptable for irrigation treatment.” Mack points out that Pascua-Lama will use untreated, lower quality water for its operations, diverting it from the mixing zone, and thereby improving overall water quality further downstream.
Water used in the processing of ore will be captured, recycled, and re-used to minimize withdrawal of fresh water from the Estrecho and Las Taguas river systems. The entire operation will draw only about 0.5% of the water in the Huasco River, which flows into the Huasco Valley’s Santa Juana Reservoir. That works out to about 42 L/sec, whereas river flow is 3,800 to 4,580 L/sec. On the Argentinean side, where the mine’s processing plant will be located and more water is required, the operation has been permitted to draw about 6.0% of water from Las Taguas. Contact of other surface and groundwater with operations will be minimized. As there are no planned discharges to the environment, any water that comes into contact with facilities will be captured, pumped to treatment plants and re-used.
Stringent water monitoring
Under approved water monitoring plans, monitoring starts on the property on both sides of the border and continues 45 km downstream in Chile and more than 100 km downstream in Argentina.
An extensive system of water monitoring will encompass both surface and underground water levels to ensure water availability and quality remains the same or improves. In total, 87 water monitoring points have been identified to safeguard water quality, 26 automated to provide real time reporting, with most results instantly accessible to regulators and communities via the web. In Chile, audits will be conducted by state authorities and independent auditors to ensure compliance with stringent water quality standards and laws. In Argentina, a participative monitoring program will involve authorities and the community.
“One of the most significant and innovative structures is a cutoff wall that will be located at the headwater of the Estrecho River in Chile,” said Mack. “The wall will offer an added level of protection by acting as a barrier to prevent water which may come into contact with the operation from entering the river system.”
Other environmental features
In Argentina, the tailings ponds have been designed with an impervious system of multiple barriers of protection to prevent pond water from contacting groundwater. The operation’s primary crusher will feed into underground ore passes and then onto a conveyor belt tunnel, transporting ore downhill over a distance of 4.7 km to the process plant on the Argentinean side of the operation. The short overland section of the conveyor belt will also be enclosed. This minimizes dust and particulate emissions into the atmosphere, and generates clean electrical energy for operational use. Other dust control measures include road watering and the choice of transportation routes away from the ice bodies. All hazardous materials will be managed in closed circuit systems featuring secondary containment.
Harnessing wind power
Barrick has invested $70 million to build the Punta Colorada wind farm project near Pascua-Lama, in the Coquimbo region of Chile. The renewable power project will feature 18 wind turbines and inject 36 MW of energy into Chile’s power grid. The large wind farm supports the Chilean government’s objective of enhancing the generation of clean energy, while addressing the country’s energy deficit. Pascua-Lama will draw all of its electrical energy from suppliers to the grid. Barrick is currently installing 20 MW in the first phase of the project.
The El Indio closure precedent
When Barrick closed the El Indio mine in Chile in 2003, it was determined to do it right.
To date, the company has spent $70 million on closure activities, an unprecedented amount in that country. Barrick worked with stakeholders and environmental authorities to develop a closu
re plan, even though it was not required, since the mine predates closure laws. The land was cleared and the stark contours of the natural topography restored. Today, the closure of El Indio is seen as a standard-setter for mine closure in Chile.
Next: A conversation with senior project engineer Mark Rookes.