Revised Waste Discharge Requirements for DV Natural Resources
The agenda item discusses the need for updating waste discharge requirements and monitoring programs for the Briggs Project. It includes permitting a bioleaching process for gold extraction, evaluation monitoring, and maintenance updates based on current site conditions. Issues such as groundwater contamination, facility history, and current site conditions are outlined for discussion and recommendation.
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Presentation Transcript
Agenda Item No. 8 REVISED WASTE DISCHARGE REQUIREMENTS FOR DV NATURAL RESOURCES AND THE U.S. DEPARTMENT OF THE INTERIOR, BUREAU OF LAND MANAGEMENT BRIGGS PROJECT Lahontan Water Board Meeting May 6, 2020 Tiffany Steinert Engineering Geologist
Reason for Action Issue Revised Waste Discharge Requirements (WDR) and update the Monitoring and Reporting Program (MRP) to: Permit Bioleaching Process to extract gold Require Evaluation Monitoring Program (EMP) Update maintenance and monitoring requirements Provide general updates based on current site conditions Rescind Board Order No. 6-01-33 Item No. 8 2
Topics of Discussion Location Briggs Mine Project Facility History Current Site Conditions Release to Groundwater Evaluation Monitoring Program Gold Extraction with Microorganisms Recommendation Item No. 8 3
Location Briggs Mine Project Item No. 8 4
Facility History Well MW-6 exceeds nitrate MCL 2018 2016 Report findings are inconclusive 1995 Mine1st permitted 2019 Staff find ponds are not being used as designed 2015 WAD Cyanide in well MW-6 exceeds WQPS 2016 Bankruptcy, Mine acquired by DVNR Item No. 8 5
Current Site Conditions No active mining Heap at >90% capacity Continue to leach the ore, but slowing down Concrete floor of processing plant in need of replacement Item No. 8 6
Release to Groundwater Weak Acid Dissociable (WAD) cyanide detected in groundwater at 0.064, more than double the WQPS on October 28, 2015 Nitrate concentrations detected in groundwater samples at 15 mg/L concentrations above the DWS on May 6, 2019 Item No. 8 7
Evaluation Monitoring Program This Order includes a requirement that the Discharger begin an Evaluation Monitoring Program (EMP) at the site: Discharger must delineate the nature and extent of WAD cyanide and nitrate impacts Discharger must develop and submit proposed corrective action measures in a Corrective Action Plan as part of the EMP Item No. 8 8
Gold Extraction with Microorganisms Construction of microorganism growth facilities Microorganisms will liberate gold still held within the heap leach pad that the cyanide could not. The microorganisms will also break down the residual cyanide within the heap leach pad (detoxification) Item No. 8 9
Recommendation Water Board Staff recommend that the Board adopt the Order as proposed Item No. 8 10
Questions? Item No. 8 11
