Water is essential to mining, but it is also a scarce commodity in many parts of the world. A commonly held perception is that the mining industry is wasteful of water.
“That’s a challenge the industry has to confront and say, ‘We’re water conscious and taking steps to conserve water,’ ” says Bill Williams, Vice President of Environment at Barrick.
The company is meeting that challenge, Williams says, noting that water management is closely monitored at Barrick operations and a key design criterion for future sites. Currently, 22 of Barrick’s 26 operating mines are zero discharge sites, meaning all water used is recycled and reused for mining processes on site.
Since 2008, Barrick has had a Water Conservation Standard that establishes a uniform approach to water monitoring and accounting. The standard creates processes for continually improving water use efficiency, and requires all sites to implement water conservation plans. Sites are also required to continuously conserve fresh water usage and reduce water inventories. “We only want to take what we need and use it to its maximum,” Williams says.
In cases where a Barrick operation discharges water, the company ensures that the water meets local legal, regulatory and permitting requirements, Williams says. The company also uses sophisticated technology to monitor water quantity and quality around its operations. For instance, at its Pascua-Lama project, which straddles the border of Argentina and Chile, Barrick has installed 30 automated water-monitoring stations at strategic points along the rivers in the site’s area of influence. The stations transmit online information about key water-quality metrics, such as pH, turbidity and flow rates. This real-time information allows project operators to detect anomalies early and take any necessary corrective action.
Representatives of communities and governments in Pascua-Lama’s area of influence also serve on water-monitoring committees that collect water samples and submit them for analysis at certified laboratories of their choice. Similar community-monitoring programs are in place at Barrick’s Lagunas Norte and Pierina mines in Peru, as well as the Veladero mine in Argentina. “The community water-monitoring programs increase transparency and underscore our commitment and confidence in the measures we are taking to maintain water quality around our operations,” Williams says, noting that Barrick is spending about $280 million to protect downstream waterways.
A large portion of that $280 million is being spent on a cut-off wall that will prevent water exposed to the mine’s waste dump from flowing into the local river system. The 140-meter wide wall will divert water into two collection ponds that can each store up to 200,000 cubic meters of water. The ponds are lined with high-density polypropene plastic, preventing leakage into the surrounding soil. Water that accumulates in the ponds will be tested for heavy metal and acidity levels and, if elevated levels are detected, treated at an on-site treatment plant. Once treated, the water can be reused in the operation or released into the river system so long as water quality meets government standards.
Barrick has also built two diversion canals at Pascua-Lama to prevent water from the upper water basin of the Estrecho River from flowing into the site’s waste dump. “We know the communities downstream rely on the water for agricultural use and that there was concern about the potential impact of the mine,” Williams says. “We think the steps we are taking address those concerns and our obligations to act in a responsible manner.”
The cut-off wall, collection ponds and canals at Pascua-Lama are just some examples of the water-management initiatives Barrick is implementing at its sites. The company is leading the way in developing innovative methods to conserve and reuse water, or find alternatives to fresh water.
For instance, at Barrick’s Jabal Sayid copper project in Saudi Arabia, the primary source of water will be treated wastewater that is trucked in daily from the city of Jedda about 350 kilometers away. At Veladero, 700 cubic meters of wastewater from the site’s mine camp is pumped daily through a four-kilometer pipeline and used in the leaching process. At the Zaldivar copper mine, located in Chile’s Atacama desert, wastewater is treated using micro-organisms and earthworms in an ecologically friendly process that recycles 46,000 cubic meters of water annually. At the Goldstrike mine in Nevada, the company is using satellite imagery to improve water monitoring by measuring water levels in aquifers deep below ground.
Because Barrick operates in many arid regions, the company has developed expertise in using brackish or saline water to meet its water needs. In 2010, 31 percent of the externally sourced water that Barrick used for its mining operations was brackish, saline or hypersaline. Using saline water has the environmental benefit of reducing soil salinity while also maximizing the availability of fresh water for irrigation, farming, ranching and other domestic purposes. The company’s Cowal mine, which is located in a drought-prone region in central Australia, is sourcing saline groundwater for a substantial portion of its mining activities. The mine, which routinely engages the community in its water management and use, reduced intake from fresh water sources by 26 percent between mid-2008 and mid-2010. It has set a 2011 target for a 10 percent reduction from the previous year and is on track to meet this goal.
To avoid tapping into water aquifers near its Buzwagi mine in Tanzania, Barrick deploys a rainwater harvester, which collects rainwater and funnels it into reservoirs that can store up to 1.5 million cubic meters of water. The 75-hectare harvester supplies the majority of the mine’s annual water requirements. “Buzwagi is one of the only places in the world that uses this rainwater harvesting system,” Williams says.
The mining industry’s water-management obligations don’t end when a mine closes. Water flow at dormant mines must continue to be monitored and water exposed to mineralized ore bodies must be treated. When Barrick took control of the Lagunas Norte mine in Peru, it inherited the dormant Callacuyan coal mine, which closed many years earlier without proper remediation. Barrick agreed to rehabilitate the old mine site, removing all mineralized ore bodies near the Callacuyan Lagoon and covering them with a clay layer to prevent acid rock drainage. Barrick is also treating contaminated water at the site by using passive treatments, which involve combining contaminated water with organic matter that removes heavy metals and restores the water to a neutral pH level. “We made obligations to communities and governments that we’re going to maintain water quality, and we’re living up to that commitment,” Williams says.