The Ite Tailings Reserve, located in the Bay of Ite, in the Department of Tacna in southern Peru, was formed as a result of the disposal of tailings from SPCC’s operations at the Toquepala and Cuajone concentrators by the sea. A successful program of environmental remediation has been carried out at this reserve forming the largest wet- lands with the greatest diversity of aquatic birds on the coast of Peru.
Formation of the Ite tailings reserve
The exploitation of the Toquepala and Cuajone mines, which began in 1960 and 1976, respectively, supplies the concentrator plants, which process the ore concentration corresponding to each unit. In this process, the ore is crushed, milled, and then benefited by floating, meaning the usable ore, which represents less than 1% of the material processed, is recovered by being floated with foaming agents to then be concentrated to produce the final product. The inert material representing over 99% of the ore processed is removed by the lower section of the floating system as tailings.
From the start of operations at Toquepala and Cuajone until December 1996, the concentrators had discharged a total of 785 million tons of tailings, sent downriver from the operations through dry ditches, to eventually be deposited into the sea, at the opening of the Locumba River in the Bay of Ite. As of 1996, the tailings from both concentrators are deposited inland in the Quebrada Honda Tailings Dam.
The smallest particles (clays and mud) were deposited offshore in the densest sands, which were deposited on sea’s edge. This material deposited at the sea’s edge contained on average 4% primary iron sulfurs (pyrite). Sands that were deposited on the beach formed the Ite Tailings Reserve. Currently, this reserve contains 40% of the total tailings discharged into the sea. The accumulation of the sands caused the beach to grow, pushing back the sea, and so by December 1996, the beach had grown to cover a total area of more than 1,600 hectares, one and a half kilometers wide and 12 kilometers long.
The portion of tailings deposited on the beach came into contact with the waters emerging from the filtrations from the irrigation of farmlands found on the terraces near the Bay of Ite. The presence of water made the pyrite oxidize on coming into contact with the oxygen in the atmosphere, creating a pH that was more acid than the water, favoring the accumulation of salts on the surface of the tailings, therefore both conditions prevented the development of vegetation on their surface.
The remediation process considered the creation of a wetland throughout the flood area of the Ite Tailings Reserve, for which berms/beds were built to retain the water coming into the area of the Reserve. To accelerate the remediation, organic material was added to improve the fertility of the tailings.
In 2002, the Peruvian Government acknowledged the commitment for the remediation of the Ite Tailings Reserve, which SPCC had included in the PAMA, had been satisfied.
Currently, maintenance activities con- tinue in the area, especially in terms of water control and management to guarantee the long-term stability of the wetlands.
The permanency of the wetlands has created a very biodiverse ecosystem, due to the abundance of food and the variety of life zones that exist in the Ite Tailings Reserve, where indigenous plant species are found, such as the saltgrass and verdolaga and later, rushes and bulrushes. At total of 144 species of birds have been identified in the wetlands through sightings made over the last few years. As birds continue to be ob- served, the number of sightings of new species is sure to increase.