Edith River Flooding Event Investigation
On 27 December 2011, a freight train owned and operated by Genesee & Wyoming Australia Pty Ltd (GWA) and travelling north to the Port of Darwin derailed at the Edith River Bridge Crossing, which is about 42 kilometres northwest of Katherine, in the Northern Territory. The Edith River Bridge Crossing is located about 250 metres to the northeast of the Stuart Highway.
The derailment occurred following high rainfall associated with Cyclone Grant.
Approximately 240 tonnes of freight, a crew van, 16 containers, and 130 kibbles (tarpaulin- covered containers) carrying an approximate total dry load of copper concentrate of 1500 dry metric tonnes (DMT), overturned into the Edith River. The copper concentrate in the kibbles originated from the OZ Minerals Prominent Hill copper-gold mine in South Australia and was being transported to the Port of Darwin for export.
This incident was reported to the Department of Lands, Planning and Environment (DLPE) (formerly Department of Natural Resources, Environment, the Arts and Sport- NRETAS).
Mt Todd Mine
On the same day as the derailment, Vista Gold Australia Pty Ltd (Vista Gold) reported a suspected uncontrolled discharge (later confirmed) from the Mount Todd Mine Site to DLPE.
The Mount Todd Mine Site is located in the Edith River catchment, approximately 55 kilometres north of Katherine, 250 kilometres south of Darwin, and 10 kilometres upstream of the Edith River Bridge Crossing.
Uncontrolled discharges from Retention Pond 1 (RP1) occurred via a spillway within the Vista Gold mining lease boundaries. RP1 collects water runoff from a large portion of the mine site. The water flowed over the spillway designed to maintain the structural integrity of the retention pond walls. Water was released into West Creek and discharged into the Edith River approximately 2 kilometres downstream of the Edith Falls Road crossing. Discharge from the site is regulated by a waste discharge licence.
Uncontrolled discharges from the mine continued from 27 December 2011 until 5 January 2012 (inclusive).
Given DLPE’s (now NT EPA) role under the Waste Management and Pollution Control Act and the Water Act, and the potential for environmental harm to the Edith River ecosystem, DLPE undertook an independent assessment of the impact posed by pollutants associated with the copper concentrate from the train derailment and discharges from the mine on the Edith River.
The findings of the investigation are provided in DLPEs investigation report: Assessment
of Harm on Edith River associated with Train Derailment and Wastewater
Discharges from Mount Todd Gold Mine (27 December 2011 – 5 January
2012), December 2012.
This report is provided below.
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|Appendix A: Declaration of Beneficial Use
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|Appendix B: Decision Tree for Metal Speciation
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|Appendix C: Decision Tree for the Assessment of Contaminated Sediments
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|Appendix D: Data Quality Objectives, Quality Assurance, Quality Control
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|Appendix F: Laboratory Certificates of Analysis and Field Data Sheets
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|Appendix G: Water Quality Summary of Results
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|Appendix H: DTA Reports, SW10, Control 4 and Control 5
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|Appendix I: DTA Report and SSD, RP1
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|Appendix J: Total Toxicity of a Mixture Calculation Results
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|Appendix K: Sediment Quality Summary of Results
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|Appendix L: UoM Lead Isotope Analysis and CSIRO Report
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