Hydrogeology, High Lake Rob Dickin Hydrogeologist, GLL

Overview Brief background Discussion of key issues Summary of commitments Recent comments –INAC –NRCAN –KIA

Background Bedrock Geology Lake Taliks Baseline Data Collection Conceptual Model Groundwater Model

Felsic to ultramafic metavolcanics (country rock) Intrusive hornblend/biotite granodiorite Diabase dykes Hydrogeological Conceptual Model: Vertical north-south trending bedding planes Bedrock Geology

2005 Drilling in West Zone

Winter Drilling into High Lake Talik

Hydrogeological Field Program Packer tests in five boreholes Country Rock, High Lake Talik

Hydrogeo Conceptual Model

Structure of the Groundwater Model

Gw flow Groundwater flow beneath permafrost Lakes with through talik Shaded dark blue

Overview of Recent Comments Recommendations and information requests raised on Nov. 23, 2007 by INAC review NRCan (reviewers 1, 2, 5) KIA (Rescan review team) Note: past comments responded to from Environment Canada

Key Issues Identified Issue 1. Shallow seepage from High Lake TCF to lakes L15 and L4 (Granite L.) Issue 2. Groundwater transport and attenuation from High Lake TCF to Kennarctic River and Granite Lake (L4) Issue 3. Potential for groundwater seepage into West Zone underground mine ramp near or beneath lakes L12/L14/L22

Issue 1. Shallow Groundwater Seepage Issue #1 Potential for shallow groundwater seepage in active layer from High Lake TCF to lakes L15 and L4 (Granite L.) This issue involves permafrost engineering and water quality in TCF as well as hydrogeology Following 4 slides will help with discussion

Shallow Groundwater Flow from High Lake Attachment to INAC_58 response

Permafrost Aggradation Attachment to NRCAN_6 response

L15L4 Assumed Depth of saturated flow, Ds (m) 55 Width of flow, W (m)18338 Ave. Distance between High Lake and receiving environment dx, (m), Hydraulic conductivity, (m/s)10 -5 Seepage Parameters

To L15To L4 year year year year 4 to year year Estimated seepage from High Lake by year, m3/day

Issue 2 Attenuation of contaminants along deep groundwater pathway from High Lake TCF to Kennarctic River and Granite Lake (L4) Involves water quality in High Lake TCF Clarify and discuss Following 4 slides for assisting discussion

Groundwater flow from High Lake Talik Observed concentration reduction takes place over the first segment of the groundwater flow pathway (about 25 m). Additional attenuation capacity is available in the remaining section of the flow path from Kennarctic River to High Lake (about 800 m).

Salinity and trace metal transport Geochemical batch modeling in PHREEQC-V2 Cadmium – affected by salinity due to complex formation Zinc and copper – no change due to complex formation

Geochemical Modelling Simplified assumption that attenuation is primarily due to surface complexation onto hydrous ferric oxides (HFO’s) Two scenarios were simulated for cadmium complexation –(1) baseline - existing cadmium attenuation was matched by adjusting the concentration of surface sites –(2) future: attenuation capacity of cadmium in the presence of higher salinity was assessed using the calibrated parameters

Effect of salinity on attenuation Cadmium attenuation decreases in presence of salinity from a factor of 33  4 Result of a chloride-cadmium complex that does not readily attenuate

Issue 3 Potential for groundwater seepage into West Zone underground mine ramp near or beneath lakes L12/L14/L22 Involves mine planning, grouting, hydraulic conductivity testing 12 m of permafrost and 70m of rock following slide shows section for discussion

L12/L14/L22 groundwater seepage

List of Hydrogeology Commitments by Proponent 1.Collect additional hydrogeology baseline data 2.Update and recalibrate MODFLOW model 3.Improve assessment of mine inflow quality after obtaining samples from beneath permafrost in year 5 4.Improve assessment of shallow groundwater flow from High Lake TCF to L15/L4 after collecting shallow groundwater baseline data (Key Issue #1) 5.Implement long-term permafrost monitoring program 6.Reassess transport of contaminants from TCF to receiving environment after collection of additional baseline water quality data

New Baseline Data new data for MODFLOW model update includes: ground temperature (permafrost)data, groundwater lake leakage rates, hydraulic conductivity data, hydraulic head data update model with new data by the end of year 5

INAC Hydrogeology Overview INAC made 5 recommendations to improve the hydrogeological assessment Of the original 12 information requests, 10 responses were accepted Issue for discussion identified within shallow groundwater assessment (key issue #1)

INAC Rec #33: Hydrogeology Model Recalibrate flow and quality groundwater model with additional baseline data: –Three talik groundwater samples and K values –K values and pressure from four West Zone boreholes drilled by year five –Sample deep groundwater quality –K values in shallow active zone around the perimeter of High Lake Zinfex accepts recommendation #33

INAC Rec # 34: Climate Change INAC recommends that a monitoring plan be put in place to monitor the permafrost condition on a long-term basis. The additional information gathered should be included in the periodic updates to the groundwater model. Zinfex accepts recommendation #34

INAC Rec #35: Groundwater Contamination Assessment of groundwater impacts resulting from facilities / activities such as the use of chemicals, and the potential for contaminant releases into the environment, such as from spills Provide a monitoring and mitigation plan for groundwater protection related to these facilities / activities Clarify and discuss recommendation

INAC Rec #36: Environmental Impacts Assess additional contaminants of concern that may be present in High Lake during operation and closure Identify whether there are other issues / contaminants that may be of concern Impact predictions and associated mitigation measures should be revisited as further site specific information becomes available Monitoring and mitigation plan for closure should be updated Clarify and discuss recommendation

INAC Rec #37: Monitoring The final EIS should include further detail on the groundwater monitoring program, and Indicate the mechanism whereby the monitoring results will be used to update and verify/ calibrate the groundwater model. Clarify and discuss recommendation

Remaining INAC IR Issues INAC #50: Plans were outlined to obtain additional baseline hydrogeology data (agreement has been reached) INAC #57: Proponent should outline mitigation measures that can be applied if the operational measures are not sufficient to maintain permafrost beneath L12/L14/L22 (key issue #3)

NRCan Review Nov 23 Reviewer 1, issues A3 and A4 Reviewer 2, Issues B1, B3, B4 Reviewer 5, issue E2

NRCan Reviewer 1 A3: protecting L15 and L4 from shallow seepage from TCF –thermal issues need to be resolved before the groundwater issues can be addressed (discussion with Jim Cassie for Key issue #1) A4: protecting L12/L14/L22 from closed talik becoming and open talik –comments are helpful for resolving issue (discussion with P. Davis for key issue #3)

NRCAN Reviewer 2 B1 is similar to A4, key issue #3 B3 follows A3, key Issue #1 –Leslie Gomm required for discussion of longer term closure and monitoring requirements B4 is key issue #2 –Attenuation argument has uncertainties. Zinifex could assess pathway with no attenuation, –Zinifex has committed to reducing uncertainty by sampling additional talik water under HL –Tailings cover issues (LG)

NRCAN Reviewer 3 E2 is similar to B4 (Key Issue #2) –Zinifex has agreed to sample more groundwater (Conclusion No. 3) –Zinifex is not planning to define the elemental transport and attenuation mechanism for this level of the permitting process

KIA Review 11 of the thirteen issues raised by the KIA are dealt with in Volumes 1 to 11 of the DEIS –Detailed response can be provided if required Issue 45: Arbitrary assumption of one order of magnitude variation in hydraulic conductivity –Proponent commits to complete the sensitivity analysis recommended by KIA in future modelling. Issue 51: Attenuation modeling based on one sample –Rescan suggests a conservative assumption would be to consider no attenuation… –Similar to NRCAN B4 issue (Key Issue #2). Further talik groundwater sampling will be completed.

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