Since Barrick began operating the Pueblo Viejo mine in the Dominican Republic, the once acidic waters of the nearby Margajita River have become cleaner. Carlos Tamayo, Environmental Manager at Pueblo Viejo, recently addressed more than 400 delegates from 31 countries at a conference in Santiago, Chile, to explain how the site remediated the river.
“To me, this invitation was recognition of the good work we are doing at Pueblo Viejo,” Tamayo told Beyond Borders.
The 10th Annual International Conference on Acid Rock Drainage focuses on mining’s water management practices and provides a forum for industry leaders to share ideas and best practices.
“Our environmental management is based on our commitment to leave the site in better conditions than those we found it in.”
Tamayo began his presentation with a detailed overview of Pueblo Viejo’s recent history. He explained that the site’s previous operator, which operated the mine from 1975 to 1999, declared bankruptcy without a proper environmental clean-up, leaving a legacy of acid rock drainage that contaminated local waterways. Acid rock drainage refers to the acidification of water that occurs when sulfur-based rock—prevalent at Pueblo Viejo—is exposed to air and water. Under the previous operator, acidic water was often discharged untreated into the Margajita, causing the river to literally run red due to the high levels of acidity.
During his presentation, Tamayo showed photos of the acidified river, which shocked the audience, but the real wow factor came towards the end of the presentation when Tamayo showed photos of the rehabilitated Margajita.
“Pueblo Viejo exemplifies how sustainable mining can manage water and the environment for the benefit of communities,” Tamayo said during his presentation. “Our environmental management is based on our commitment to leave the site in better conditions than those we found it in.”
The change in the Margajita was the result of Pueblo Viejo’s state-of-the-art water treatment plant, which opened in 2012—the year that Barrick began producing gold at the site. (Barrick operates the mine and holds a 60 percent stake; Goldcorp holds the remaining 40 percent.) Some of the Margajita’s tributaries, such as the Hondo River, have also been positively impacted by the site’s water treatment process and become less acidic, Tamayo told the audience.
Throughout his presentation, Tamayo stressed how important planning was to the overall success of Pueblo Viejo’s environmental clean-up of the site. First, his team had to identify how acidic water was produced at the site and in what quantities. They then implemented a range of prevention and control measures to reduce the amount of water that would need to be cleaned at the site’s treatment plant. These measures included the construction of separate channels to capture storm water and acid rock drainage. Not only do these channels help minimize acid rock drainage from storm water, they also ensure that acidic water stays within the site and that it is funneled to collection ponds that pump the water to the treatment plant.
Another vital component to environmental management is engagement with the community through environmental monitoring, Tamayo said. Local communities, their leaders, government officials and other local stakeholders are invited by the mine four times a year to collect water, soil and air samples. The samples are sent to independent labs in Puerto Rico or Canada for analysis. This monitoring is in addition to government and independent third-party inspections of the mine. These activities help to build trust and ensure transparency with Pueblo Viejo’s local stakeholders.
“Our colleagues at this conference saw that this community participation is real,” Tamayo told Beyond Borders. “This is a successful example of community engagement that we hope will be followed in the rest of Latin America and other parts of the world.”