MV2002L2-0019 MV2014D0012 Dehcho First Nations { North American Tungsten Ltd’s Drystack Tailing Application ‐ Intervention
Dehcho First Nation’s Perspective • Cantung mine is in the traditional territory of the Dehcho First Nations • Several communities are downstream of the Cantung mine including Nahanni Butte and Fort Simpson • Boat travel, fishing and hunting and other traditional harvest activities are important for subsistence and way of life in the Dehcho • DFN’s ultimate goal for participating in this process is to ensure that the water quality and overall health of the Flat River is maintained.
DST Application – TSF4B, TSF7 & TSF6 TSF7 TSF4b TSF6
Size of the Drystack Tailings Facilities TSF 4B 210,000 (tons) TSF 6 20,350,000 (tons) TSF 7 728,700 (tons) Total 21,288,700 (tons) 2014 – Total tailings – 7,348,000 tons Total proposed tailings (old tailings + new tailings) = 22,907,100 tons
Acid Rock Drainage Potential • Majority of tailings considered potentially acid generating (sulphur content 4% or higher) • High neutralization potential (presence of dolomites and carbonates) • Significant lag to the onset of acidic conditions • If tailings do become acidic, the concentration of parameters in the leachate increases many ‐ fold.
Original Review of NATCL’s Application • DFN had several main concerns: • High quantity of proposed drystack tailings for TSF 6 • Potential risks and impacts of acid generation and metal leaching at the site • No Closure and Reclamation Plan for the Site • No Aquatic Effects Monitoring Program
Original Review of NATCL’s Application DFN felt that permit/license applications constituted a significant alteration to existing operations. DFN requested that the Board screen the application and send it to an environmental assessment. MVLWB screened the application and agreed that the mine expansion was a significant alteration to the project. However, the Board decided to not move the application to EA. DFN still has concerns regarding the quantity of tailings at TSF6 and the impacts associated with acid generation.
NATCL Technical Sessions DFN not opposed to Drystack Tailings Applications but has outstanding concerns from the Technical Sessions: • Risks associated with ARD & Metal leaching • Tailing Storage Facility Cover System & Process • Application of MMER • Flat River Floodplain & potential impacts to drystack tailings
Risks associated with ARD & Metal Leaching • The tailings are potentially acid generating • High quantity of tailings – 21.3 million tons for the proposed tailings (TSF4B, TSF7 & TSF 6) compared to 7.3 million tons for the existing tailings • Significant environmental concerns associated with ARD • Difficulty in accurately predicting ARD
Integrated Load Balance and Risk Assessment TSF6 • Report is key to DFN’s concerns as it addresses: Model outputs of concentrations to the Flat River from TSF6 • Sensitivity analysis on climate variability and extreme events, • flushes of contact water during spring freshet and worst case ARD development. • DFN expects that given the significant lag times NATCL will be looking at long ‐ term scenarios • Expect that NATCL will address accuracy associated with predictions • Report will not be completed until Jan 2016
DFN’s Recommendations – ARD Risks • MVLWB put conditions on the Water License that TSF6 not be constructed until DFN and other reviewers can review and discuss the Integrated Load Balance and Risk Assessment for TSF6 and can determine that there is a low potential for ARD and potential impacts to the Flat River. • Technical sessions be held regarding ARD and impacts to the Flat River prior to construction of TSF6.
Tailing Storage Facility Cover System • NATCL proposed to test cover designs at TSF4B to inform the cover designs in TSF7 and TSF6. • Detailed information is required on: the types of cover they will be testing and the types of testing that will occur or where they will get the source material for their covers. • DFN is supportive of this approach.
NATCL’s proposed Water License Conditions TSF6 The Licensee shall submit to the Board for approval, a Final Cover Design Report for TSF6, 90 days prior to construction. The design reports shall be signed and stamped by an Engineer and shall include, but are not limited to, the following: • a. Engineering design drawings – stamped by an Engineer • b. Issued for construction specifications; • c. A construction quality control and quality assurance plan
DFN’s Recommendation – Tailing Storage Facility • NATCL provide an explanation of the types of testing that will occur at TSF4B and how these elements will inform elements of construction/design of the tailings facilities and till cover for TSF7 and TSF6. NATCL should also provide information on where the source material will come from. • NATCL provide a link between testing at TSF4B and the Final Cover Design Report. • DFN agrees with NATCL’s proposed Water License conditions. We also recommend that a technical session be held regarding the types and thicknesses of covers prior to the construction of TSF6 so consensus can be reached on appropriate mitigation measures.
Application of MMER • Environment Canada indicated that any runoff from the dry stack tailings is considered effluent and must be collected and treated and if necessary, monitored and discharged through a final discharge point. • Want more clarification from EC and NATCL on MMER
Application of MMER • NATCL has proposed the use of a soil liner to manage seepage. • DFN needs more clarification from EC and NATCL on seepage from the drystack tailings and water quality concerns. • DFN also requests mechanism in the Water License to address seepage, soil liners and water quality concerns prior to the construction of TSF6.
Flat River Floodplain • TSF6 will be constructed 120m away from the Flat River.. The closest proximity of TSF6 is about 60 meters. The flow in this areas is not expected to exceed 0.5m in depth. NATCL is proposing 0.6m thick rip ‐ rap blanket on the TSF slope for erosion control. • NATCL is proposing a Flood Control and Action Plan be included in the Water Management Plan. Will be submitted 90 days prior to construction of TSF6. • DFN is proposing this item also be addressed in Technical sessions.
Aquatic Effects Monitoring Program & Closure and Reclamation Plan • DFN is working with NATCL and other partners in the development of an AEMP and Closure and Reclamation Plan for the Site. • We look forward to working on this processes in the future including the development of an AEMP working group and comprehensive literature review.
Conclusion • DFN needs more clarity on the following: Tailings cover systems in TSF 6 • Acid rock drainage and metal leaching in TSF 6 and long ‐ term • risks to the Flat River Seepage and runoff water in TSF4b, TSF7 & TSF6 – how it will be • gathered, processed and discharged into the Flat River
Conclusion • DFN believes that the best way to deal with unresolved issues raised by the reviewers is to create a step ‐ wise process to the licensing. • Specifically, not approving TSF6 until NATCL can provide information on: • “Integrated Load Balance and Risk Assessment TSF6” • Cover design for TSF6 • Finally, DFN requests that MVLWB facilitate a second technical session to address concerns outlined above and any other concerns from other reviewers regarding TSF6.
Recommend
More recommend
