Long Lake Gold Reclamation Update. May 25, 2016 SNC Lavalin - MNDM 1

Transcription

1 Long Lake Gold Reclamation Update May 25, 2016 SNC Lavalin - MNDM 1

2 Agenda 1. Site Background 2. Conceptual Reclamation Plan 3. Supporting Activities 4. Detailed Design a) Bathymetric survey b) Tailings and Contaminated Soil Volume assessment c) Geotech Investigation d) Detailed Design of the Tailings Impoundment (60% complete) e) Hydrologic Assessment and Water Management f) Tailings Removal Methodologies from Long Lake g) Water Treatment during Construction (IN PROGRESS) h) Species at Risk Assessment Studies May 25, 2016 SNC Lavalin - MNDM 2

3 4,400 abandoned mines in AMIS database Class D (low risk) contain tailings 56 Crown sites with booked liability May 25, 2016 SNC Lavalin - MNDM 3

4 Long Lake Gold - Background Atikameksheng Anishnawbek May 25, 2016 SNC Lavalin - MNDM 4

5 Long Lake Gold - Background Ore body consisted of gold-bearing arsenopyrite and pyrite. Mine operated from 1909 to 1916 & from 1937 to 1939 Mine produced: o 56,742 oz Au o 221,000 tons milled at a average grade of 0.26 oz/ton. May 25, 2016 SNC Lavalin - MNDM 5

6 Long Lake Gold - Background Underground workings extend to 345 ft (105m). Site contains both open pit (glory hole) and underground working which are currently flooded. May 25, 2016 SNC Lavalin - MNDM 6

7 Preferred Conceptual Reclamation Conceptual Site Model: Tailings are primary concern (not mine water or waste rock) Pathway is primarily surface water erosion of tailings and runoff from tailings area (flushing of oxidation products) Groundwater is being re-evaluated. Options Evaluated based on following criteria: feasibility of implementation and effectiveness long-term care and maintenance requirements Service life (i.e. time to replacement) minimizing potential impacts to stakeholder concerns regulatory requirements cost of implementation and care and maintenance Options Included: Off-site processing Off-site disposal Relocate to the open pit Consolidate and encapsulate on Site Long-term Treatment of runoff/seepage May 25, 2016 SNC Lavalin - MNDM 7

8 Preferred Conceptual Rehabilitation Preferred Conceptual Plan Construct new impoundment at TA- 01 Consolidate tailings in new impoundment (through excavation and dredging). Tailings in Long Lake removed max. 2 m below water surface. Re-establish drainage around impoundment and in Luke Creek and wetland Allow Long Lake water quality to recover on its own now that source is minimized. May 25, 2016 SNC Lavalin - MNDM 8

9 Supporting Activities LiDAR Survey Completed May 2014 Airborne survey using laser technology to map the mine site area, Providing updated topography and aerial photography for the site. May 25, 2016 SNC Lavalin - MNDM 9

10 Archaeological Assessment Purpose is to evaluate areas that will be disturbed by reclamation activities for archaeological values prior to completing reclamation work. Supporting Activities Site inspection identified approximately 20% of reclamation area that was not already disturbed. Areas that were not visibly disturbed, permanently wet, or slopes were subjected to a stage 2 assessment. AA staff were in attendance. No archaeological resources were identified within the areas that will be affected by the site reclamation work. May 25, 2016 SNC Lavalin - MNDM 10

11 Supporting Activities Fish Tissue Sampling Sampling completed by MOECC Long Lake Fall 2013 Round Lake Fall 2014 Skinless, boneless dorsal fillets were tested for metals, mercury and arsenic. Results for Long Lake (2013) Consumption of Cisco and Small Mouth Bass are restricted due to arsenic ( Guide to Eating Ontario Sport Fish). Arsenic does not cause consumption restrictions for any other species in the South or Central Basins of Long Lake. Consumption advisories for other fish species are similar for both the South and Central Basins and unrelated to the Mine. Results for Round Lake (2014) Walleye, N.Pike, SM Bass, Cisco and Rainbow Smelt were captured in There are no consumption restrictions related to Arsenic for fish in Round Lake. All consumption limits are related to mercury, except Smelts, which are limited by Chromium. May 25, 2016 SNC Lavalin - MNDM 11

12 Summary of Data Collected to Date Joint water sampling in Round Lake with Atikameksheng Anishnawbek staff show water in Round Lake is below Federal Drinking Water Guideline of 10 ug/l for total arsenic. Fish tissue sampling was completed in the fall of Proposed Consumption Limits for : Walleye and Pike remain similar to the current guidelines. Rainbow Smelt will be more restrictive than the current guidelines due to chromium contamination. Small Mouth Bass are new as they were not included in the current consumption guidelines. Total Arsenic Concentration (ug/l or ppb) 06-Dec Aug Jun Aug Jun Aug Total Arsenic concentration as measured at Round Lake Outlet (RL-3) Based on fish sampled in 1994 Results based on Hg contamination only Based on fish sampled in 2014 Reduction reflects Cr contamination Bass not captured previously May 25, 2016 SNC Lavalin - MNDM 12

13 Detailed Engineering & Design (2015) Winter 2015 SNC Lavalin Inc initiated soil sampling program to support the detailed design of the conceptual reclamation plan. Data collection to support: Tailings excavation work Design of the impoundment Water management during construction Final site grading and drainage permitting. Work Completed to Date a) Bathymetric survey b) Tailings and Contaminated Soil Volume assessment c) Hydrologic Assessment and Water Management d) Geotech Investigation e) Detailed Design of the Tailings Impoundment (60% complete) f) Tailings Removal Methodologies from Long Lake g) Water Treatment during Construction (IN PROGRESS) h) Species at Risk Assessment Studies May 25, 2016 SNC Lavalin - MNDM 13

14 Bathymetric Survey May 25, 2016 SNC Lavalin - MNDM 14

15 Bathymetric Survey Long Lake Bathymetric Survey Complete in Long Lake at Luke Creek discharge. Long Lake water level varies 0.6 m to 0.9 m seasonally Tailings that are permanently flooded will not leach arsenic. Proposing minimum 2 m water cover over any remaining tailings May 25, 2016 SNC Lavalin - MNDM 15

16 Tailings and Contaminated Soil Volumes May 25, 2016 SNC Lavalin - MNDM 16

17 Tailings & Contaminated Soil Volumes Tailings & Contaminated Soil Volumes 245 soil samples were collected; 408 samples were sent for laboratory test work Analyses included: Metals (As, Cu, Co, Fe, and Ni) Static Acid Base Accounting Shake Flask Extraction Testing May 25, 2016 SNC Lavalin - MNDM 17

18 Tailings & Contaminated Soil Volumes Tailings & Contaminated Soil Volumes - TA-01 Max. arsenic was 65,000 ppm based on 105 samples Of 43 ABA samples, 91% were PAG Avg. SFE leachate As concentration exceeded MISA 40 times Contamination (arsenic) was found to have leached into native soils underlying tailings to a significant depth significantly increasing material volumes in TA-01. May 25, 2016 SNC Lavalin - MNDM 18

19 Tailings & Contaminated Soil Volumes TA-02 and samples collected for metals. Max. arsenic was 81,000 ppm. 39 ABA samples collected 74% PAG 43 SFE samples collected. Avg. leachate concentration of arsenic was 41 times MISA (limit 1 mg/l). Review of historic aerial photography (1927, 1949, 2014) suggest tailings extend beyond the current footprint. Bedrock is relatively shallow (<3m) and all contaminated material is expected to be removed. Excavated areas to be backfilled and graded to prevent ponding water. May 25, 2016 SNC Lavalin - MNDM 19

20 Tailings & Contaminated Soil Volumes Luke Creek and Wetland 145 samples collected for metals. Max. arsenic was 18,000 ppm. 80 ABA samples collected 72% PAG 90 SFE samples collected. Avg. leachate concentration of arsenic was 0.9 mg/l (MISA limit 1 mg/l). Contamination was found to be substantially more extensive than was initially thought. Additional sampling in Feb.2016 found with the exception of the creek channel, contamination was generally less than 1.2m depth May 25, 2016 SNC Lavalin - MNDM 20

21 Tailings & Contaminated Soil Volumes Photos: Luke Creek Wetland Summer (top); Spring (bottom) May 25, 2016 SNC Lavalin - MNDM 21

22 Tailings & Contaminated Soil Volumes Long Lake Delta 66 samples collected for metals. Max. arsenic was 21,000 ppm. Avg result in underlying clay 21 ppm. 58 ABA samples collected 33% PAG 56 SFE samples collected. Avg. leachate concentration of arsenic was 3.5 times MISA (MISA limit 1 mg/l). Contamination is extensive and extends into Long Lake to the limits of the sampling program. Contamination appears to be relatively shallow (1.5 m) and does not appear to extend significantly into underlying clay. Contaminated material deeper than 2 m below lake level will be capped with sand and gravel and left in place. Material outside of the 2m depth clean up zone will be left in place. 2 m Boundary May 25, 2016 SNC Lavalin - MNDM 22

23 Tailings & Contaminate Soil Volumes Summary of Material Volumes May 25, 2016 SNC Lavalin - MNDM 23

24 Geotechnical Investigation May 25, 2016 SNC Lavalin - MNDM 24

25 Field Program Area Borehole ID Depth (m) In-Sit Testing TA-01 BH BH BH MW/BH BH BH BH BH BH BH BH BH SPT, FV, PP* SPT, FV, PP SPT, FV, PP SPT, FV, PP SPT, FV, PP SPT, FV, PP SPT, FV, PP SPT, FV, PP SPT, Packer SPT, Packer SPT, Packer SPT, Packer SPT, Packer BH BH SPT BH SPT TA-02 BH SPT BH SPT TA-03 BH SPT July 6-13, 2016 October 14-16, 2015 (MW repair) May 25, 2016 SNC Lavalin - MNDM 25

26 Geotechnical Analyses Depth to bedrock 9m-19m used in analyses (based on BH15-01, BH15-02, BH15-05, BH15-08) Estimated settlement between 0.5m 1.6m Primary Consolidation Borehole Number Depth to Bedrock (m) Soil Thickness (m) Estimated Primary Consolidation (mm) 9.0 BH15-01 BH BH15-05 BH Existing Tailings 2.0 Native Soil , , ,600 May 25, 2016 SNC Lavalin - MNDM 26

27 Geotechnical Analyses cont d May 25, 2016 SNC Lavalin - MNDM 27

28 Geotechnical Analyses cont d Time vs. Degree of Consolidation at TA-01 Estimated 50% of Consolidation at BH15-08 May 25, 2016 SNC Lavalin - MNDM 28

29 Impoundment Design May 25, 2016 SNC Lavalin - MNDM 29

30 Design Criteria Remove tailings and contaminated material from (adopted from feasibility study by CH2MHILL): TA-02 TA-03 Luke Creek Wetland Long Lake Consolidate contaminated material at TA-01 Design impoundment to ensure: Stable facility No discharge of contaminated water to the surrounding environment Minimal construction cost Encapsulate contaminated material. Cover objectives: Dust and erosion control Minimum rainfall / snow melt water infiltration Suitable growth medium May 25, 2016 SNC Lavalin - MNDM 30

31 Phase 1-TA-01 May 25, 2016 SNC Lavalin - MNDM 31

32 Phase 1-TA-01 Foundation Preparation and Rock Drains Construction Rock drains proposed for the groundwater control within the impoundment Available material on the site to be used for construction May 25, 2016 SNC Lavalin - MNDM 32

33 Phase 1-TA-01 Preparation PERIMETER BERM DETAILS Tailings and contaminated material to be removed and replaced by clean fill material Different perimeter berm design options were evaluated Cut and fill methodology found to be most feasible Cut and fill material in balance Geomembrane is proposed for berm (downstream) to prevent contamination of clean runoff Containment berm will be part of permanent containment facility May 25, 2016 SNC Lavalin - MNDM 33

34 Phase 2 Excavation at TA-02 and TA-03 ~60,000m 3 May 25, 2016 SNC Lavalin - MNDM 34

35 Phase 3- Luke Creek May 25, 2016 SNC Lavalin - MNDM 35

36 Phase 4-Luke Creek Wetland and Long Lake Delta Long Lake Delta-~36,000m 3 Luke Creek Floodplain-~54,000m 3 May 25, 2016 SNC Lavalin - MNDM 36

37 Phase 5 Cover Construction TYPICAL SECTION COVER DETAILS May 25, 2016 SNC Lavalin - MNDM 37

38 Water Management May 25, 2016 SNC Lavalin - MNDM 38

39 Water Management May 25, 2016 SNC Lavalin - MNDM 39

40 Water Management cont d May 25, 2016 SNC Lavalin - MNDM 40

41 Water Management cont d May 25, 2016 SNC Lavalin - MNDM 41

42 Water Management cont d May 25, 2016 SNC Lavalin - MNDM 42

43 Water Management cont d May 25, 2016 SNC Lavalin - MNDM 43

44 Tailings Removal Methodologies Long Lake Delta May 25, 2016 SNC Lavalin - MNDM 44

45 Tailings Removal Methodologies cont d Removal Criteria (adopted from CH2MHIL) Remove and relocate contaminated material with less than 2 m of water cover Leave in place tailings or contaminated sediments that are submerged with a minimum of 2 m of water at all times (i.e. at low water level in lake) Rehabilitate excavated delta areas, including installation of protective layer of sand and gravel over footprint of removed tailings to stabilize underlying sediment and minimize scour effects Continue water quality monitoring May 25, 2016 SNC Lavalin - MNDM 45

46 Tailings Removal Methodologies cont d Excavation and Stockpile Excavation and Disposal Directly to TA-01 EXCAVATION DREDGING Mechanical Dredging (Clamshell) and Cyclone Mechanical Dredging (Clamshell) and Geotextile Tubes Hydraulic Dredging and Cyclone Hydraulic Dredging and Geotextile Tubes May 25, 2016 SNC Lavalin - MNDM 46

47 Tailings Removal Methodologies cont d REMOVAL METHODOLOGY SELECTION CRITERIA Ease of Permitting and Public Perception AMD Control/ML Dust Control and Physical Stability Hydrological Considerations (Water Management) Cost Other Environmental Considerations Constructability and Construction Duration and Schedule Source: TENCATE May 25, 2016 SNC Lavalin - MNDM 47

48 Tailings Removal Methodologies cont d PREDERMINED EVALUATION CRITERIA FOR CONTRACTOR Proposed methodology to meet clean up criteria Feasibility of implementation and effectiveness of proposed approach Health and Safety targets Environmental compliance Execution strategy and cost of implementation. Source: TENCATE May 25, 2016 SNC Lavalin - MNDM 48

49 Water Treatment Water treatment requirements are still being evaluated. Issues that will be considered include: Active treatment of runoff from disturbed areas during reclamation Treatment of drainage from dredged/excavated material Treatment of water that collects in the impoundment during construction and filling. Long term treatment of groundwater seepage from impoundment May 25, 2016 SNC Lavalin - MNDM 49

50 Species at Risk May 25, 2016 SNC Lavalin - MNDM 50

51 Surveys were conducted in Spring & Summer 2015 for: Eastern Whip-poor-wills Eastern Massasauga Blanding Turtles Migratory Birds Whip-poor-wills and Blanding Turtles were identified on or near the site area. Blanding Turtles habitat is defined as 2 km from the occurrence for connected wetlands and water-bodies Eastern Massasauga None were observed. Historic observation on Lakes End Road. Species at Risk May 25, 2016 SNC Lavalin - MNDM 51

52 Species at Risk Eastern Whip-poor-will Sensitive to up to 500 m from recorded occurrence Next Steps: It is believed that the Site Remediation work is eligible for the ESA Threats to Health and Safety not imminent exemption (S.23.18) S is a proponent-led process with no requirement for MNRF approval, however MNRF staff are certainly available to provide advice as needed No mitigation plan required, however requirement to minimize adverse effects (S.23.18(5)5). Upgrading Access Road is NOT eligible for exemption because footprint is being enlarged and will require an A-Permit. A-Permit process does not involve any formal application form or the consideration of overall benefit measures. A-Permit does require mitigation of impacts to the Species at Risk/habitat as well as rationalization that there is a threat to human health or safety for which Access Road is required. May 25, 2016 SNC Lavalin - MNDM 52

53 Tentative Schedule Tentative schedule based on current understanding of the site conditions Schedule will be updated as new information becomes available Construction sequence is currently unknown. Seasonal restrictions, species at risk issues, etc. may delay or extend construction schedule. Start Finish Activity Nov April 2016 Detailed Design Complete Field Work & Data Collection April 2016 Dec Detailed Design Preparation of Cost Estimate, Draft Drawings & Specs, Consultation Dec Dec Permitting, Funding, Construction Tender & Award Jan 2018 Dec Site Remediation Spring 2021 As Required Post Remediation Monitoring, Maintenance and Repair May 25, 2016 SNC Lavalin - MNDM 53

54 Other Site Reclamation Work 54

55 Engineered Dry Covers Kam Kotia Mine Timmins Sulphide tailings (Cu, Zn) 60 ha engineered cover installed using geosynthetic clay layer (GCL) May 25, 2016 SNC Lavalin - MNDM 55

56 Tailings Impoundments Placing HDPE Liner at Kam Kotia Tailings Impoundment Construction of Tailings Impoundment at Kam Kotia Covering GCL at Kam Kotia (winter work). Winter tailings removal from North Creek, Kam Kotia. May 25, 2016 SNC Lavalin - MNDM 56

57 1992 Then and Now Kam Kotia Mine at discharge to Little Kamiskotia River May 25, 2016 SNC Lavalin - MNDM

58 Then and Now Zenmac Mine Tailing dusting issue controlled through revegetation. Cover does not limit infiltration or groundwater seepage from tailings. May 25, 2016 SNC Lavalin - MNDM 58

59 Long Lake Gold Reclamation Questions / Comments May 25, 2016 SNC Lavalin - MNDM 59