Miramar Northern Mining Limited - Con Mine Remediation MV2017L8-0008 - - PowerPoint PPT Presentation

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Miramar Northern Mining Limited - Con Mine Remediation MV2017L8-0008 Technical Workshop July 4 and 5, 2018

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How Did We Get Here?

Dec 2017

• Water Licence Submission

March 1/2

• First Technical Session
• EQC, modelling, monitoring

March 23

• Discharge Criteria Concept Meeting
• Discussion on how to address stakeholder concerns, focus on

chloride

May 23

• Technical Workshop
• Overview of approach
• No results at that time

June 15

• Second Technical Session
• New limits for chloride
• Proposed delineation of regulatory mixing zone
• Additional monitoring – plume study and AEMP

Peg Lake 2017

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Additional Studies Since March 2018

Effluent Quality Criteria for Chloride 1. Lab Study - Site-specific acute toxicity threshold for chloride using site-relevant waters 2. Desktop Study - Chronic SSWQO for chloride in the downstream receiving waters 3. Model chloride concentrations in receiving water for different loading scenarios 4. Develop EQC for chloride Regulatory Mixing Zone 5. Propose mixing zone boundary Future Monitoring 6. Develop Draft AEMP

Meg Lake 2017

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Where to Find the Material - EQC

Task Main Report1 Appendix A Appendix B Appendix C Effluent Quality Criteria for Chloride  Develop a site relevant acute threshold for chloride  Evaluate proposed chronic SSWQO for chloride  Model chloride loading scenarios in M-K-P lakes & Jackfish Bay  Compare predictions to site-specific acute threshold & SSWQO  Regulatory Mixing Zone within Jackfish Bay  Compare model predictions to SSWQO  Evaluate sampling depths and accessibility  Future plume validation and monitoring 

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Where to Find the Material - AEMP

2Report on Draft Aquatic Effect Monitoring Program Outline (Golder 2018b)

Section in Main Report2 Description 1.0 Introduction Background and regulatory framework 2.0 Site Characterization Characterization of site, treated effluent discharge and receiving water 3.0 Conceptual Site Model Identification of stressors, environmental pathways, receptors, measurement and assessment endpoint 4.0 Study Design Outline of study area, components, and sampling locations, frequency, and type 5.0 Response Framework Development of significance thresholds, Action Levels and potential response if Action Levels triggered 6.0 Reporting Requirements for AEMP reporting

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Additional Chloride Toxicity Studies Completed

Keg Lake 2017

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Objective: Identify acute toxicity threshold of chloride, in a site-relevant mixture

• Effluent and downstream receiving environment samples frequently

exceed short-term CCME WQG (640 mg/L Cl)

• Future chloride concentrations in treated effluent are uncertain, but could

be higher than recent concentrations

• A site-specific threshold for acute chloride toxicity will help inform water

management decisions and non-lethality is met at compliance and monitoring stations

Acute Chloride Toxicity Study - Overview

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Acute Chloride Toxicity Study – Study Design

Collected representative base water from Peg Lake Measured base chemistry—Treatments were amended in-lab to achieve total chloride targets (base plus amendment) using mixture-specific recipes Mixture A Low SO4 Mixture B Moderate SO4 Mixture C High SO4 A0 A1 A2 A3 A4 B0 B1 B2 B3 B4 C0 C1 C2 C3 C4

Base water (unamended)

Conducted spiked chloride tests:

• D. magna (48-h), O. mykiss (96-h)

Base water plus low chloride Base water plus moderate chloride Base water plus high chloride Base water plus very high chloride

Site chloride 5,000 3,500 1,500 2,500 Target chloride levels (mg/L): Lab Control Lab Control Lab Control

Standard laboratory negative control (high hardness)

Exposure Scenarios Cl- approximately equal across treatment levels, but relative ionic composition differs among Mixtures A, B and C

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Acute Chloride Toxicity Study – Study Design

• Reviewed current and future,

modelled ionic composition

• Study focused on chloride and

sulphate

• main constituents of interest
• exhibited largest variance
• Selected 3 ion composition

mixtures

Mixture B Mixture C

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Acute Chloride Toxicity Study – Study Design

Mixture A

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Scenario Description Ionic Composition (%) Mixture A Low Sulphate Mixture B Moderate Sulphate Mixture C High Sulphate Station SNP 0040-5 SNP 0040-1 SNP 0040-1 Time Period Existing Conditions Average August to October (2015 to 2017) Future Conditions Scenario 2 (2018 to 2028) Existing Conditions Maximum June to September (2015 to 2017) Description

• 10% SO4 (of TDS)
• 55% Cl
• Represents dry conditions
• 20% SO4 (of TDS)
• 49% Cl
• Intermediate mixture
• 33% SO4 (of TDS)
• 35% Cl
• Current ion composition of

effluent

Acute Chloride Toxicity Study – Scenario Selections

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Acute Chloride Toxicity Study – Results

Survival (%) Measured chloride (mg/L) Measured chloride (mg/L)

• D. magna Responses:
• Test validity criteria met for

all controls

• Acute lethality occurred at

chloride concentrations > 2,500 mg/L in all Mixtures

• 48-hr LC50 (survival &

immobility) ranged from 2,894 to 3,086 mg/L

Mixture A Mixture B Mixture C

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Acute Chloride Toxicity Study – Results

Mixture A Mixture B Mixture C

Survival (%) Measured chloride (mg/L) Measured chloride (mg/L)

Rainbow Trout Responses:

• Variable response
• Low, but acceptable control

mortality (10% mortality)

• No clear concentration-

response

• 96-hr LC50 ranged from >4,820

to 5,220 mg/L Cl Survival (%)

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Acute Chloride Toxicity Study – Discussion

• Acute toxicity threshold should focus on D. magna

as the more sensitive species For D. magna:

• Threshold response in this study similar to

published toxicity results (2,565 to 3,630 mg/L chloride; Elphick et al. 2011; Mount et al. 1997; Biesinger and Christensen 1972)

• Toxicity results were generally similar across the

mixtures

• Acute chloride toxicity unlikely to occur under

current, or future predicted conditions at concentrations ≤ 2,500 mg/L

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Chronic Chloride Site Specific Water Quality Objective

• Objective: validate interim chronic site-specific water quality objective (SSWQO) of

388 mg/L (derived using Elphick et al. 2011 hardness-dependent chloride equation)

• Validation procedure:

I.

Reviewed recently published literature (2011 to 2018) for new toxicity data

II.

Multiple lines of evidence considered (e.g., approaches applied at northern mine sites)

III.

Applied site-specific conditions of environmental and toxicity modifying factors

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Chronic Chloride Site Specific Water Quality Objective – Literature Review

• New data from Streuwing et al. (2015) indicated

high sensitivity of mayfly (Centroptilum triangulifer) to chloride under long-term exposure (14-d IC25 dry weight = 138 mg/L)

• Not a common test species but increasingly

applied in freshwater toxicity testing (Conley et

• al. 2009; Xie et al. 2010)

University of Iowa / www.discoverlife.org

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Chronic Chloride Site Specific Water Quality Objective – Elphick et al. (2011) Model

Elphick et al. (2011) Hardness-dependent Model

• Conducted acute and chronic toxicity testing

with nine freshwater species

• Derived an HC5 using species sensitivity

distribution for tox data (15 species) collected under hardness of 80 to 100 mg/L (as CaCO3)

• Additional toxicity testing indicated strong

ameliorating effect of hardness on acute and chronic chloride toxicity

• Derived a hardness-dependent equation,

applicable over a water hardness range of 10 to 160 mg/L: 𝑋𝑅𝑃 = 116.63 𝑦 ln ℎ𝑏𝑠𝑒𝑜𝑓𝑡𝑡 − 204.9

Elphick et al. 2011

Ceriodaphnia dubia response to chloride toxicity is positively correlated to water hardness

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Chronic Chloride Site Specific Water Quality Objective – Con Mine SSWQO

Elphick et al. (2011) model with Streuwing data incorporated

• Elphick equation remains an appropriate

model (used for chronic SSWQO at Ekati)

• Streuwing study of sufficient quality to include

in SSWQO derivation and conducted under hardness range of 80 to 100 mg/L

• Using Elphick approach incorporated IC25 for
• C. triangulifer into chronic toxicity dataset
• Derived an updated hardness-dependent

equation, applicable over a water hardness range of 10 to 160 mg/L as CaCO3 𝑋𝑅𝑃 = 79.02 𝑦 ln ℎ𝑏𝑠𝑒𝑜𝑓𝑡𝑡 − 138.28 SSD with C. triangulifer Updated hardness-dependent equation:

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Chronic Chloride Site Specific Water Quality Objective – Con Mine SSWQO

Elphick et al. (2011) model with Streuwing data incorporated

• Median hardness at all locations in Jackfish

Bay higher than calibrated range

• SSWQO derived from maximum calibrated

hardness (160 mg/L as CaCO3)

• SSWQO = 260 mg/L Cl (rounded to two significant figures)

𝑋𝑅𝑃 = 79.02 𝑦 ln ℎ𝑏𝑠𝑒𝑜𝑓𝑡𝑡 − 138.28 SSD with C. triangulifer Updated hardness-dependent equation:

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Additional Desktop Study Completed – Chloride EQC and Mixing Zone

Keg Lake 2017

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Chloride EQC and Regulatory Mixing Zone

Outline of Chloride EQC and Regulatory Mixing Zone

• Methods for determining chloride EQC and regulatory mixing zone
• Incorporation of supporting chloride studies
• Predicted concentrations in receiving water
• Proposed EQC for chloride and regulatory mixing zone
• Next steps

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Treated Effluent and Receiving Water Characterization

<0.5 m <1 m 1.5 m

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Mean Chloride Concentrations in Treated Effluent and Receiving Water

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Determination of EQC and Regulatory Mixing Zone

Development of Effluent Quality Criteria for chloride

• Discharge concentrations should not be acutely toxic
• Discharge concentrations and loadings should not cause:
• acute toxicity within the regulatory mixing zone
• chronic toxicity beyond the boundary of the regulatory mixing zone

Determination of a proposed regulatory mixing zone within Jackfish Bay

• Chronic SSWQO for chloride met most of the time under typical hydrological conditions
• Location is accessible and expected to be within an appropriate sampling depth

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Methods for Determining Chloride EQC

Steps to Develop Effluent Quality Criteria for Chloride 1. Compare predicted treated effluent concentrations to acute toxicity threshold 2. Ran the Models

• 15 loading scenarios = 5 WTP effluent Cl concentrations X 3 hydrological conditions
• WTP effluent Cl concentrations: 0, 2,000, 2,300, 2,500 and 3,000 mg/L
• Hydrological conditions: dry, average and wet conditions

3. Compare predicted Cl concentrations in M-K-P to acute threshold and scenario with no WTP discharge 4. Compare predicted Cl concentrations in Jackfish Bay to chronic SSWQO and scenario with no WTP discharges

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Model Predictions for Meg, Keg, and Peg Lakes

Water Treatment Plant Scenarios Comparison of Predicted Concentrations in Meg, Keg, and Peg Lakes Hydrological Conditions Volume (m3/yr) Chloride Concentrations in Effluent (mg/L) Loading (kg/yr) To Acute Toxicity Threshold To Predicted Concentrations in No Water Treatment Plant Scenario Dry 100,000 2,000 200,000 Above Decrease 2,300 230,000 Above Decrease 2,500 250,000 Above Decrease 3,000 300,000 Above Decrease Average 180,000 2,000 360,000 Below Increase 2,300 414,000 Below Increase 2,500 450,000 Below Increase 3,000 540,000 Below Increase Wet 250,000 2,000 500,000 Below Increase 2,300 575,000 Below Increase 2,500 625,000 Below Increase 3,000 725,000 Below Increase

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Proposed Effluent Quality Criteria for Chloride

Chloride Effluent Quality Criteria Value Maximum grab concentration 2,500 mg/L Annual loading limit 450,000 kg/yr

• Concentrations in the treated effluent will not be above the acute toxicity threshold (2,500 mg/L)
• Concentrations within the regulatory mixing zone will be either:
• < 2,500 mg/L (ave/wet) or
• < concentrations without WTP discharges (dry)
• Exception: 95th percentile at Meg Lake (ave)
• Low risk for acute toxicity within the regulatory mixing zone because predictions are:
• an over-estimate because discharge concentrations will typically be less than 2,500 mg/L
• < the range where toxicity was observed in the acute toxicity study

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Model Predictions for Jackfish Bay

Predicted Concentration in Jackfish Bay Hydrological Conditions Dry Average and Wet Median 400 m 200 m 75th Percentile 1,000 m 600 m 95th Percentile >1,000 m >1,000 m

Regulatory Mixing Zone

• Determine distance in Jackfish Bay where chronic SSWQO is met most of the

time under typical hydrological conditions

• Evaluate location for site accessibility and suitability for sampling (e.g., adequate

depth) Distances from the Inlet of Jackfish Bay Where the Chloride Site-Specific Water Quality Objective is Predicted to be Met for All Water Treatment Scenarios:

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Proposed Regulatory Mixing Zone

• Meets SSWQO for chloride at 600 m most of

the time (>75% of the time) during average hydrological conditions

• Location is accessible by boat for field crew
• Depths at 600 m from the inlet of Jackfish Bay

are expected to be greater than 1 to 1.5 m during average hydrological conditions

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Proposed Effluent Quality Criteria for Chloride

Chloride Effluent Quality Criteria Value Maximum grab concentration 2,500 mg/L Annual loading limit 450,000 kg/yr

• Concentrations at the edge of the MZ will be either:
• < the chronic SSWQO (75% of the time for ave/wet) or
• not different from concentrations without WTP discharges (other conditions)

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Additional Desktop Work Completed – Development of Draft AEMP

Keg Lake 2017

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Monitoring and Proposed AEMP

• Plume validation
• Effluent
• SNP (WQ, compliance for acute toxicity and evaluation of chronic toxicity)
• Chloride loading will be calculated based on weekly analytical analysis, and

flowmeter readings

• Meg, Keg, and Peg lakes monitoring will be determined through the Working Group
• AEMP
• Builds on SNP and EEM monitoring + additional monitoring at the edge of the

regulatory mixing zone boundary

• Response Framework to address potential concerns in the receiving water

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AEMP Outline

• Site characterization
• Conceptual Site Model
• Study Design
• Response Framework
• Reporting

Peg Lake 2017

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Conceptual Site Model

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Assessment and Measurement Endpoints

• What is assessed?
• The ecological function of Jackfish Bay (including benthic invertebrate community

and fish health) is preserved.

• How will it be measured?
• Exposure - potential exposure of receptors to Mine-related chemicals, including

surface water and sediment.

• Effects - potential ecological changes, including measures of benthic invertebrate

abundance community structure and fish health.

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AEMP Sampling Schedule for the 2018 to 2021 Period

Component 2018 2019 2020 2021 Site characterization √ √ √ √ Water quality √ √ √ √ Toxicity √ √ √ √ Sediment quality √(a) √(a) Benthic invertebrates √(a) √(a) Small bodied- fish health √ √

a) Biological sampling to occur on a three year cycle, consistent with federal metal mining EEM programs, which use annual water and toxicological samples paired with a tiered, three-year cycle for biological sampling.

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Monitoring Outline for AEMP - Water Quality and Toxicity

Component Frequency Timing Sampling Depth Sample Type Parameters or Species Monitored Number of Stations Water quality – SNP annually monthly during periods of open- water grab sample (surface) discrete routine (e.g., pH, TDS, TSS, alkalinity, hardness), major ions, nutrients, metals, cyanide Meg Lake: 1(a) Peg Lake: 1(b) Water quality – MDMER and AEMP annually monthly during discharge from WTP grab sample (surface) discrete routine, major ions, nutrients, metals, cyanide Meg Lake: 1 Keg Lake: 1 Grace Lake: 1 Jackfish Bay: 3(c) Toxicity – SNP annually twice (at the beginning and end of the

• pen-water

season) grab sample (surface) discrete static pass/fail bioassay for Rainbow Trout and D. magna (water flea) Peg Lake: 1(b) Toxicity – AEMP annually twice during discharge grab sample (surface) discrete sub-lethal toxicity testing should be completed for Fathead Minnow.), C. dubia (water flea), L. minor (Lesser Duckweed), and P. subcapitata (an alga) Jackfish Bay: 3(c) a) Channel of Meg Lake b) Outflow of Peg Lake. It is recommended that consideration be given to monitoring toxicity at a different location within the mixing zone to avoid backwater/pooling conditions during low flows that occur here. c) At the edge of the regulatory mixing zone.

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Component Frequency Timing Sampling Depth Sample Type Parameters or Species Monitored Number of Stations Benthic invertebrates*

• nce every

3 years

• nce during open-

water 10 to 15 cm in sediment in water depth of approximately 1 m or less composite of 5 Ekman grabs

• inner Jackfish Bay

(near-field): 5

• uter Jackfish Bay

(mid-field): 5 Kam Bay: 5 Sediment quality*

• nce every

3 years

• nce during open-

water top 5 to 10 cm composite of 3 Ekman grabs TOC, moisture, particle size, metals, nutrients, major ions inner Jackfish Bay (near-field): 5

• uter Jackfish Bay

(mid-field): 5 Kam Bay: 5 Fish health*

• nce every

3 years

• nce during open-

water

• Ninespine

Stickleback Fish Survey lethal and non-lethal lethal: up to 100 Ninespine Stickleback (target 40 males, 40 females, 20 juveniles) per area non-lethal: additional 100 YOY Ninespine Stickleback per area Jackfish Bay and Horseshoe Island Bay (number of stations not applicable)

Monitoring Outline for AEMP - Benthic Invertebrates, Sediment Quality and Fish

*Aligned with MDMER

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Reporting for AEMP

• Final AEMP Design Plan – 2019
• First AEMP Data – June 2019
• AEMP Report – date TBD, pending licence
• Aquatic Effects Re-evaluation Report - date TBD
• AEMP Response Plans submitted if Action Level triggered

*All data/reports submitted to the MVLWB, Design Plan and AEMP annual reports shared with ECCC

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Overview of AEMP Response Framework

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Conceptual Overview of Action Levels Relative to Significance Threshold

Significance Threshold: The ecological function of Jackfish Bay is preserved.

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Low Action Levels - Water Quality and Toxicity

Tiered Action Level Water Quality and Toxicity Ecological Integrity Maintained Measurement Endpoint Water Quality Toxicity Key Information acute AEMP WQOs differences between current and historical water quality within the mixing zone (i.e., at Peg Lake outflow or alternate location within the mixing zone) differences between current water quality in the mixing zone and in reference lake chronic AEMP WQOs differences between water quality at the edge

• f the mixing zone and historical water quality

Jackfish Bay differences between water quality at the edge

• f the mixing zone and in reference lake or

area toxicity results within the mixing zone (i.e., at Peg Lake outflow or alternate location within the mixing zone) or at the edge of the mixing zone Negligible concentration not exceeding acute AEMP WQOs within the mixing zone, or if exceeding, not due to WTP discharges AND within reference lake range or historical range within the mixing zone concentration not exceeding chronic AEMP WQOs at the edge of the mixing zone, or if exceeding, not due to WTP discharges AND within reference lake range or historical range within the mixing zone no acute toxic effects to test organisms within the mixing zone AND no concurrent or consecutive sublethal toxic effects to test organisms at the edge of the mixing zone Low concentration greater than historical and reference range supported by a temporal trend AND exceeding 75% of an acute AEMP WQO within the mixing zone concentration greater than historical and reference range supported by a temporal trend AND exceeding 75% of a chronic AEMP WQO at the edge of the mixing zone

• ne acute toxic effects to test
• rganisms within the mixing zone

OR consecutive or concurrent sublethal toxic effects to test organisms at the edge of the mixing zone

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Low Action Levels - Biological Components

Tiered Action Level Benthic Invertebrates and Fish Health Ecological Integrity Maintained Measurement Endpoint Benthic Invertebrates Fish Health Key information differences between Jackfish Bay and reference area or normal range; trends over time in Jackfish Bay and reference area differences between Jackfish Bay and reference area or normal range Negligible density and richness between Jackfish Bay and reference area(s) are statistically the same. weight, relative gonad size, relative liver size, or condition between Jackfish Bay and reference area(s) are statistically the same Low density and richness between Jackfish Bay and reference area(s) exceed a critical effect size weight, relative gonad size, relative liver size, or condition between Jackfish Bay and reference area(s) are above a critical effect size Rationale/ comments Statistically different is defined using critical effects size as per EEM (i.e., exposure outside of ±2SD of index in reference area). Statistically different is defined using critical effects size as per EEM:

• weight (total weight or carcass weight) = 25%
• relative gonad size = ±25%
• relative liver size = ±25%
• condition = 10%

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Summary

• Recap of the day
• Key areas of agreement
• Follow-up items

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