DE BEERS GAHCHO KUÉ WATER LICENCE AMENDMENT HEARING PRESENTATION Lynx Room, Chateau Nova, Yellowknife July 25-26, 2018
AGENDA • Summary of Amendment Application - Changes to mine plan and mine water management - Overview of amendment application • Key Responses to Interventions from DFO, ECCC, and GNWT - Water use - Effluent quality criteria (EQC) - Amendments to SNP - Discharge timing and monitoring - Response framework and action levels - Air quality - Offsetting plan and downstream flow mitigation The De Beers Group of Companies 1
GAHCHO KUÉ MINE • Gahcho Kue is owned by a Joint Venture Partnership • Located 280 km northeast of Yellowknife, 140 km from Lutsel K’e • Open Pit Mine: 5034 Pit, Hearne Pit, and Tuzo Pit • Mine Life: 2 Years Construction, 11.6 yrs Operation, 2 yrs Active Closure, and 19 yrs re-filling Kennady Lake The De Beers Group of Companies 2
BASIS FOR THE WL AMENDMENT A A Ne New Chall Challenge f for the Mine – r the Mine – Joint sets in oint sets in all three pits all three pits BFA 85° BFA 70° 6m 2m • A joint joint is a break (fracture) of natural origin in the Planned break- continuity of the rock back • A joint set joint set is a family of parallel, evenly spaced joints • When joint sets joint sets are blasted, blast pattern is affected • Rock is not only breaking along vertical blast lines, Actual break- but also along the joint sets back 24m • Results in reduction of the catch benches – leading to safety issue for workers below • 5034 pit has joint sets on the eastern wall 90° • Issue extends to Tuzo and Hearne pits • Necessary to re-design slope walls to accommodate additional break-back and preserve bench widths for safety The De Beers Group of Companies 3
KEY OUTCOME – EXTRA MINE ROCK • Pit shapes will change; wall slopes decrease • Additional mine rock will be produced - Planned case = 65 Mt - Worst case = 100 Mt • Where does the extra mine rock go? - Alternatives Analysis conducted to examine best design for mine rock management - Parameters considered: • Containment within Controlled Area • Minimized footprint on land and in water • Close proximity to pits • Minimized height increase • Technical feasibility • Feedback received from Aboriginal Parties during previous reviews The De Beers Group of Companies 4
WEST MINE ROCK PILE – SELECTED DESIGN Sele Selected and Refi and Refine ned Opti Option on Capacity 130 Mt Height increase 35 m Total height 135 m Proximity to pits Close Land increase 7.1 ha Water increase 55.4 ha Key Features: • Footprint within Controlled Boundary • Drainage channel from D lakes required at closure The De Beers Group of Companies 5
HOW DOES THIS LARGER MINE ROCK PILE CHANGE AFFECT THE MINE? Operations Operations • Increased footprint • Adjustments to water management • Additional camp occupancy and annual camp water intake • Additional mining equipment and operating hours • Some additional infrastructure within camp • Life of mine extended by 7 months Closur Closure • Longer to refill Kennady Lake • Constructed diversion channel required to reconnect D Watershed to Kennady Lake The De Beers Group of Companies 6
CHANGES TO PLANNED DISCHARGE TO LAKE N11 AND AREA 8 Additio tional Y al Year of Dischar of Discharge t to Lak Lake N1 N11 1 (Y (Yea ear 4; r 4; Sept Septem ember t r to No November 2020) 2020) • Annual allotment remains same as licenced = 3.45 Mm 3 /yr • Discharge planned for Sep 1 to Nov 1 • EQC evaluation report submitted • If EQC are met in WMP beyond Year 4 (2020), discharge can continue under same conditions Discharge fr Discharg from om Area Area 7 7 to Area 8 Area 8 • Supplemental source of downstream flow mitigation water to Area 8 • ~1.55 Mm 3 as available from natural watershed runoff during Life of Mine (~4 time periods during LoM) • EQC evaluation report submitted Contingency opti Conti y option f on for st r stora orage of WMP of WMP water in r in Area Area 7 7 • WMP water storage could be temporary (i.e., pumped back to WMP or a pit) • Water discharged to Area 8 if contingency EQC are met (EQC evaluation in response to IR #1) The De Beers Group of Companies 7
RESPONSES TO INTERVENTIONS
CAMP WATER USE AND DEFINITION OF MODIFICATION Wa Wate ter U Use • De Beers is seeking 45,000 m 3 /y, with a bridging amendment for 2018 = 35,000 m 3 /y - GNWT Recommendation 5 ecommendation 5.1 stated no concern with request • De Beers requested confirmation that no additional sampling would be required during discharges that crossed the anniversary date of the Water Licence. - GNWT Recommendation 5 ecommendation 5.2 supported the request as long a regular SNP monitoring occurred during discharge Def Defini niti tion of Modi on of Modifi ficati cation on • De Beers stands by the request for amendment to the term ‘modification’ under Part A of the Water Licence, where the definition of modification omits the exclusion of expansion (GNW (GNWT T Recommendation 6. commendation 6.1) 1) • Rationale based on recent MVLWB decisions where the increase in size (or expansion) of several internal dykes (D, A1, and L) were considered modifications The De Beers Group of Companies 9
AMENDMENTS TO SNP • The proposed wording by GNWT for condition Part G, Item 29 of the Water Licence is acceptable to De Beers ( GNW GNWT Recommendation 2.3. commendation 2.3.1a 1a ) - Inclusion of pre-discharge WQ results from additional SNP stations (e.g., SNP 06) close to compliance stations for consideration by the Inspector provides increased flexibility • Monitoring results provided to the Inspector prior to any discharge will include all EQC parameters, as well as any required toxicity testing outlined in the Water Licence ( GNW GNWT Recomm commendation dation 2.3. 2.3.1b ) The De Beers Group of Companies 10
EFFLUENT QUALITY CRITERIA • Same approach used to set water quality-based EQC for the Mine as in WL MV2005L2-0015 - Based on guidance from AEP (1995) and USEPA (1991) - Consistent with water quality-based EQC in Water Licences for Snap Lake Mine and Ekati Mine (Jay Project) • Step-wise process for both Area 8 and Lake N11; described in detail at the Technical Sessions • EQC developed in the EQC Report (Attachment 3 of the Water Licence Application) – WMP to Lake N11: chloride, fluoride, sulphate, nitrate, total ammonia, total phosphorus, and total aluminum, chromium, copper and iron – Area 7 (mostly composed of natural watershed runoff) to Area 8: total copper The De Beers Group of Companies 11
EFFLUENT QUALITY CRITERIA Area 7 Discharge Area 7 Discharge to Area 8 Area 8 • De Beers developed contingency EQC for discharge from Area 7 to Area 8 if WMP water is transferred to Area 7 - Contingency EQC developed that that would only be triggered if water from WMP is transferred to Area 7( GNWT R Recommendation 2 commendation 2.2.1 ) • Prior to discharge under contingency EQC condition, De Beers will use existing processes to evaluate the volume of water that could be transferred from the WMP to Area 7( ECCC CCC Recommendation 4. commendation 4.1a 1a ) - Based on water chemistry in WMP and Area 7, and volume of water in Area 7 at the time of transfer, so contingency EQC can be met - Inspector would confirm prior to discharge The De Beers Group of Companies 12
EFFLUENT QUALITY CRITERIA Lak Lake N1 N11 EQC 1 EQC • De Beers acknowledges supporting recommendations for proposed EQC ( GNW GNWT Recommend commendations 2. ations 2.1. 1.1 t 1 to 2. 2.1. 1.13, 2.2.2b , 2.2.2b ) SS SSWQOs and Nitr WQOs and Nitrogen Managem ogen Management nt • De Beers has agreed to use CCME Protection of Aquatic Life guideline as the SSWQO for cadmium ( ECCC R ECCC Recommendation 4.2 commendation 4.2 ) • De Beers will continue to review measured copper concentrations and condition of the aquatic biota in the receiving environment to evaluate potential effects ( GNW GNWT R Recommendation commendation 2.2.2a 2.2.2a and b and b ) • De Beers is committed to reducing nitrate loading to WMP ( GNW GNWT R Recomm commendations 2. dations 2.1.4 1.4 and and 2. 2.1.6 1.6 ) - Nitrogen management processes will be included in the Explosive Management Plan; the Plan will be updated to include management measures to reduce nitrate loadings to the WMP The De Beers Group of Companies 13
EFFLUENT QUALITY CRITERIA Discharge t Discharge to Lak Lake N1 N11 fr 1 from the WMP om the WMP af after Y Year 4 ar 4 (2020) (2020) • De Beers requests EQC proposed for WMP discharge to Lake N11 remain applicable for Life of Mine and not limited to just Year 4 ( GNW GNWT Recommendation 2. commendation 2.1. 1.14 ) • EQC proposed for discharge to Lake N11 are projected to be achievable in Year 5 (2021) for EQC parameters, except chloride, nitrate, total phosphorus, and total chromium • SSWQO will be met for EQC parameters for discharges to Lake N11 Year 5+ at MAC EQC, with exception of total phosphorus, aluminum, chromium, copper, and iron - Projected concentrations only slightly higher than SSWQO and limited to brief periods during under-ice conditions - Risk of any potential adverse effects low The De Beers Group of Companies 14
Recommend
More recommend
