DENVER, Feb. 15, 2013 /PRNewswire/ -- Vista Gold Corp. (TSX & NYSE MKT: VGZ) ("Vista" or the "Company") announced that it has completed the initial phase of water treatment at the Mt. Todd mine site in Northern Territory, Australia, and initiated the second phase of the program.
Additionally, on February 5, 2013, through its wholly-owned Australian subsidiary, Vista Gold Australia Pty. Ltd., Vista has received authorization from the Northern Territory (" NT") Government to release treated water from the mine site into the Edith River, subject to stringent water quality and environmental standards.
Since its initial involvement in the Mt. Todd gold project, Vista has worked closely with the NT Government to effectively manage acidic water accumulated on site. As part of the water management plan to protect the nearby Edith River system, approximately 10.3 gigaliters of water affected by acid rock drainage is currently stored in the Batman pit. Vista has undertaken laboratory, bench-scale and pilot-scale testing programs to evaluate the effectiveness of the water treatment methods to be used at the Mt. Todd gold project.
Commencing in October 2012, Vista has added over 10,000 tonnes of finely ground limestone to the water in the Batman pit. The water quality has rapidly improved with the pH rising from 3.3 to 6.4 with significant decreases in the concentrations of aluminum, copper, chromium, ferrous iron and lead due to precipitation. Vista is now adding approximately 2,000 tonnes of hydrated lime and believes water quality will continue to improve as the water approaches the pH target of 7.Vista remains committed to the protection of the Edith River system and has been authorized to release treated water only when flow rates are sufficient to ensure that Australian drinking water standards for health are achieved downstream of the mixing zone. In addition to daily water quality testing during periods of discharge, Vista will continue to conduct annual macro-invertebrate and sediment testing programs in the Edith River to ensure that there is no long-term impact to the environment.