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Mine Groundwater Treatment Study and Design of Effluent Removal

The La Coipa Mine is a large gold and silver mine located 140 kilometers west of the City of Copiapo, Chile. Our team has provided services for the evaluation and engineering of the mine¡¯s groundwater resources for the last 10 years. Because precipitation in this arid, high-elevation area is minimal, annual groundwater recharge from the Andes is an important water source for the region¡¯s agricultural economy.

The solid waste from extraction processes¡ªin the Atacoma Desert region of Chile¡ªproduces tailing materials that are disposed in a typically dry tailing disposal area identified as the Rahco waste dump. Over time, the residual tailing leachate had seeped through and contaminated the local aquifer¡ªrequiring a subsurface containment barrier to be constructed.

So, they hired us to design a treatment system that reduces the concentration of these contaminants in order to inject the treated effluent downstream of the containment barrier in the aquifer and reduce the water quality impacts in the groundwater leaving the mine site.

In 2007, we completed a feasibility level study for water treatment of effluents and groundwater seepage at the Rahco Tailings Management Facility (TMF). As a result of the study, water treatability tests were conducted to collect metals by physical-chemical treatment including coagulation, flocculation, sedimentation, and filtration. In 2010, our team prepared a comprehensive groundwater treatment and implementation approach for an effective treatment system for the facility.