Crocodile Gold - NTEPA...GHD | Report for Crocodile Gold - Pine Creek Project Area, 43/22192 | iii...

Crocodile Gold Pine Creek Project Area

Environmental Monitoring and WDL166-02 Report 2013-2014

August 2014

GHD | Report for Crocodile Gold - Pine Creek Project Area, 43/22192 | i

Executive Summary The long term water quality results show that the water quality in PCPWD is improving with an increase in pH and decrease in bioavailable metals. The ecotoxicology data from 2009 and 2013 support this, however, neither sample tested was representative of median water quality in PCPWD.

A decrease in pH at PCCK04 was observed during the 2013/14 wet season. This decrease is possibly sourced from NW WRD and backfilled International Pit seepages. Monitoring should continue at this site and further investigations should be conducted if the pH continues to decrease.

Sediment results show that zinc is present in sediments above the Interim Sediment Quality Guideline levels. The presence of zinc in the sediments is related to the high zinc concentrations in PCPWD and at PCCK04 adsorbing to the sediments downstream of the discharges. The ecotoxicology results show that toxicity is observed at PCCK06, PCCK06B and PCCK03 which can be attributed to the zinc concentrations at those sites. These results agree with the risk assessment which also detects that zinc is a high risk at PCCK06 and PCCK03, with other metals a lower risk. However, the Copperfield Creek far downstream site PCCK21 does not show any toxicity.

Even though toxicity at downstream sites was detected in the laboratory organisms, the in-situ macroinvertebrate results show that there were no significant differences in any of the univariate macroinvertebrate indices between Control site and Impact site sample groups. There was, however, significant year to year variation in Abundance, Taxa Richness and PET Richness. The latter related mainly to the very low diversity and abundance of macroinvertebrate fauna collected in 2012 and the high abundance and diversity of macroinvertebrate fauna collected in 2013.

The SSTVs calculated in this report are to be applied to the designated downstream sites for the 2014/15 wet season and then these can be recalculated using 2014/15 data for use in the next wet season. To enable better management of discharge water to meet SSTVs downstream of the discharge in Copperfield Creek, a system which allows greater control of water leaving PCPWD is required.

Recommendations

Recommendation Action

Surface Water

2.1 The Copperfield Creek 2014/15 compliance point retained at PCCK06

2.2 A mixing zone study to confirm the location of the Copperfield Creek compliance point.

2.3 Selenium and chromium are not detected in the Pine Creek or Copperfield Creek catchments and should be removed from the sampling program.

2.4 Provide a method for greater control over the volumes of water released from PCPWD to enable a better regulation of downstream dilution.

2.5 Investigate a monitoring site downstream from PCCK03

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2.6 Investigate the source of the decrease in pH at PCCK04 if the decrease continues.

Site Specific Trigger Values

3.1 Update the SSTVs on an annual basis.

3.2 Determine the mixing zones for Pine Creek and Copperfield Creek to determine appropriate monitoring locations to meet the SSTVs.

3.3 Controlled discharges to enable SSTVs to be met at downstream monitoring sites.

Sediment

4.1 It is recommended that the sediment monitoring program continues in 2015, after which the program will be reviewed, particularly for inclusion of the Pine Creek sites and if management of PCPWD discharge is modified.

4.2 Consideration should be given to removing the requirement for total metals analysis in sediment analysis. The total metals analysis does not add significant value to environmental impact interpretation process, as the ANZECC ISQGs are based on bioavailable metals.

4.3 Consideration could be given to further investigating contaminant sources that may be impacting sediment quality at PCCK03 and PCCK06B, so as to improve the understanding of sediment impacts related to mine discharge water.

Biological Monitoring

5.1 Investigate a revised study design to increase within site replication and statistical power

5.2 Sample processing methodology to be maintained

5.3 Retain SIGNAL data and review its use after the next two sampling rounds

Ecotoxicology Program

6.1 Remove all screening bioassays from the program.

6.2 Conduct the direct toxicity assessment on PCCK04 and PCPWD on a three yearly basis. As water quality monitoring is taken on a routine basis, the water quality results will provide information on the potential toxicity of the discharge water which can be confirmed with the three yearly ecotox program.

6.3 Design and implement a discharge system that can be calibrated and/or monitored to enable the application of the SSD dilution factors to the management of the discharge for environmental protection downstream of the discharge.

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6.4 Revise 2013 Ecotoxicological Monitoring Environmental Management Plan.

6.5 Investigate using water quality data and ecotoxicology results to date to determine a process where ecotoxicity can be predicted based on water quality results

Recommended Variations to WDL

Item 28

WDL Reporting requirements should be changed to annual to capture annual water quality at the end of the wet season to allow for management actions of water on site to be incorporated into the annual Water Management Plan review.

Reporting period recommended: July – June

Item 16 Retain the SSTVs to apply to PCCK06 and PCCK03

Appendix 1 Remove chromium and selenium from the monitoring program

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Table of contents Executive Summary .................................................................................................................................. i

1. Introduction..................................................................................................................................... 1 1.1 Background .......................................................................................................................... 1

1.2 Waste Discharge Licence .................................................................................................... 1

1.3 Purpose of this Report ......................................................................................................... 3

1.4 Scope and Limitations.......................................................................................................... 3

1.5 Assumptions ........................................................................................................................ 4 1.6 Data Sources ....................................................................................................................... 4

2. Surface Water Quality .................................................................................................................... 5

2.1 Introduction .......................................................................................................................... 5

2.2 Authorised Discharge Locations .......................................................................................... 5

2.3 Rainfall ................................................................................................................................. 6 2.4 Volume of Water Discharged ............................................................................................... 7

2.5 Surface Water Monitoring Program ................................................................................... 10

2.6 Surface Water Quality Results ........................................................................................... 13

2.7 Pine Creek Water Quality Trends ...................................................................................... 13

2.8 Copperfield Creek Water Quality Trends ........................................................................... 15 2.9 SSTV Exceedances 2013/14 ............................................................................................. 17

2.10 Conclusions ....................................................................................................................... 21

2.11 Recommendations ............................................................................................................. 21

3. Site Specific Trigger Values 2014/15 ........................................................................................... 22

3.1 Introduction ........................................................................................................................ 22 3.2 Sites used for SSTV Calculation ........................................................................................ 22

3.3 Data Provided by CGAO .................................................................................................... 23

3.4 Beneficial Uses .................................................................................................................. 23

3.5 Aquatic Ecosystem Trigger Values .................................................................................... 23

3.6 SSTV Exceedance Management ....................................................................................... 25

3.7 Results and Discussion...................................................................................................... 27 3.8 Selection of 2014/2015 Site Specific Trigger Values ......................................................... 30

3.9 Conclusions ....................................................................................................................... 31


4. Sediment Quality .......................................................................................................................... 32

4.1 Introduction ........................................................................................................................ 32 4.2 Sediment Monitoring Program ........................................................................................... 32

4.3 Sediment Quality Results .................................................................................................. 33

4.4 Historical Results ............................................................................................................... 42

4.5 Conclusions ....................................................................................................................... 42


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5. Biological Monitoring .................................................................................................................... 44

5.1 Biological Monitoring Program ........................................................................................... 44 5.2 Study Design and History .................................................................................................. 45

5.3 Sampling and Sample Processing Methods ...................................................................... 46

5.4 7.2.3 Data Analysis ............................................................................................................ 47

5.5 Biological Monitoring Results ............................................................................................. 52

5.6 Conclusions ....................................................................................................................... 59


6. Ecotoxicology ............................................................................................................................... 61

6.1 Introduction ........................................................................................................................ 61

6.2 Ecotoxicology Program ...................................................................................................... 61

6.3 Ecotoxicology Results ........................................................................................................ 63 6.4 Historical Ecotox Data........................................................................................................ 69

6.5 Conclusions ....................................................................................................................... 71


7. Environmental Risk Assessment ................................................................................................. 72

7.1 Introduction ........................................................................................................................ 72 7.2 Methodology ...................................................................................................................... 73

7.3 Problem Formulation .......................................................................................................... 74

7.4 Factors that Influence Impacts ........................................................................................... 80

7.5 Phase 2 – Risk Analysis .................................................................................................... 90

7.6 Phase 3 – Risk Characterisation ....................................................................................... 95

7.7 Discussion .......................................................................................................................... 95 7.8 Conclusions ....................................................................................................................... 96

8. Conclusions .................................................................................................................................. 97

8.1 General .............................................................................................................................. 97

8.2 Water Quality ..................................................................................................................... 97

8.3 Site Specific Trigger Values ............................................................................................... 98 8.4 Sediment Quality ................................................................................................................ 98

8.5 Biological Monitoring .......................................................................................................... 98

8.6 Ecotoxicology ..................................................................................................................... 99

8.7 Risk Assessment ............................................................................................................... 99

8.8 Recommended variations to WDL 166 ............................................................................ 100

9. Recommendations ..................................................................................................................... 101

10. References ................................................................................................................................. 103

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Table index Table 2-1 PCPA Authorised Discharge Points ..................................................................................... 5

Table 2-2 Waste Water Sources .......................................................................................................... 6

Table 2-3 2013/14 PCPWD Discharge Data ........................................................................................ 7

Table 2-4 2013/14 PCCK06 Flow Data ................................................................................................ 8

Table 2-5 Surface Water Monitoring Locations for WDL 166-02 ....................................................... 12

Table 2-6 Surface Water Monitoring Analytes for WDL 166-02 ......................................................... 12

Table 2-7 Pine Creek Trend Analysis (January 2010 to June 2014) ................................................. 13

Table 2-8 PCCK04 Metal and pH concentrations .............................................................................. 14

Table 2-9 Copperfield Creek Trend Analysis (January 2010 to June 2014) ...................................... 15

Table 2-10 PCCK06 Exceedances (January 2014 to June 2014) ....................................................... 18

Table 2-11 PCCK06 Water Quality (January 2010 to June 2014) ...................................................... 20

Table 3-1 Surface Water Monitoring Sites used in this SSTV ........................................................... 23

Table 3-2 ANZECC (2000) Categorisation of Pine Creek and Copperfield Creek ............................ 24

Table 3-3 2014/15 SSTV exceedance management actions (CGAO MMP 2013) ............................ 26

Table 3-4 Water Quality Data ............................................................................................................. 27

Table 3-5 Hardness Data for PCCK03 and PCCK06 (2012 to 2014) ................................................ 27

Table 3-6 Pine Creek PCCK01 Statistical Summary (July 2012 to June 2014) ................................ 28

Table 3-7 Copperfield Creek PCCK16 Statistical Summary (July 2012 to June 2014) ..................... 29

Table 3-8 Calculation of the 2014/2015 Wet Season SSTVs ............................................................ 30

Table 4-1 Sediment Monitoring Program ........................................................................................... 32

Table 4-2 Sediment Monitoring Frequency and Parameters ............................................................. 33

Table 4-3 Copperfield Creek Bioavailable Sediment Metals Amnalysis Summary (1 M HCL in mg/kg dry weight) compared to ANZECC Guidelines .................................................... 35

Table 4-4 Pine Creek Sediment Bioavailable Metals Analysis Summary (1 M HCL in mg/kg dry weight) compared to ANZECC guidelines ........................................................ 36

Table 4-5 Copperfield Creek Sediment Analysis Summary – pH, TOC, sulphate, sulphur and particle size ................................................................................................................. 40

Table 4-6 Pine Creek sediment analysis summary –pH, TOC, sulphate, sulphur, and particle size ........................................................................................................................ 41

Table 5-1 Biological Monitoring Locations and Sampling History ...................................................... 45

Table 5-2 Macroinvertebrate Indices used as part of this Assessment ............................................. 49

Table 5-3 Key to O/E50 AUSRIVAS Scores and Bands .................................................................... 50

Table 5-4 Results of Two-Way ANOVA comparing Abundance between Treatments and Sampling Occasions (years). Values in red indicate a significant effect .......................... 52

Table 5-5 Results of Two-Way ANOVA comparing Taxa Richness between Treatments and Sampling Occasions (years). Values in red indicate a significant effect ................... 53

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Table 5-6 Results of Two-Way ANOVA comparing PET Richness between Treatments and Sampling Occasions (years). Values in red indicate a significant effect ................... 54

Table 5-7 Results of Two-Way ANOVA comparing SIGNAL between Treatments and Sampling Occasions (years) .............................................................................................. 55

Table 5-8 Results of Two-Way ANOVA comparing AUSRIVAS O/E50 between Treatments and Sampling Occasions (years) ................................................................... 57

Table 5-9 Results of PERMANOVA analysis comparing community composition between treatment and sampling occasions (years). Values in red indicate significant differences ......................................................................................................................... 59

Table 5-10 Taxa that contributed most to dissimilarity in macroinvertebrate community composition between Control and Impact Sites based on SIMPER Analysis ................... 59

Table 6-1 Ecotox Monitoring Locations .............................................................................................. 61

Table 6-2 Ecotox Bioassays ............................................................................................................... 62

Table 6-3 Chemistry Analysis ............................................................................................................ 63

Table 6-4 Summary of PCPWD ecotox results .................................................................................. 64

Table 6-5 Summary of Copperfield Creek Screening Ecotox Results ............................................... 64

Table 6-6 Summary of PCCK04 Ecotox Results ............................................................................... 64

Table 6-7 Summary of Pine Creek Screening Ecotox Results .......................................................... 65

Table 6-8 Species Sensitivity distribution results ............................................................................... 66

Table 6-9 Chemistry Results Dissolved Metals (9 April 2013, Envirolab Services CoA 88633) ................................................................................................................................ 67

Table 6-10 Historical Screening Toxicity Data ..................................................................................... 69

Table 6-11 Historical PCPWD Toxicity Data (ERISS 2010) ................................................................ 69

Table 6-12 PCPWD Chemistry Data .................................................................................................... 70

Table 7-1 PCCK01 Pine Creek (upstream) Summary Data (2010 to 2014) and ISSTVs.................. 75

Table 7-2 PCCK16 Copperfield Creek (upstream) Data Summary (2010 to 2014) and ISSTVs ............................................................................................................................... 76

Table 7-3 PCCK04 Pine Creek (Authorised Discharge Point) Data Summary (2012 to 2014) and ISSTVs .............................................................................................................. 78

Table 7-4 PCPWD Copperfield Creek (Authorised Discharge Point) Data Summary (2010 to 2014) and ISSTVs.......................................................................................................... 79

Table 7-5 PCCK02 Pine Creek (downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs ............................................................................................................. 81

Table 7-6 PCCK03 Pine Creek (Compliance Point/downstream) Data Summary (2012 to 2014) and 2013/2014 ISSTVs ........................................................................................... 82

Table 7-7 PCCK06 Copperfield Creek (Compliance Point/downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs ............................................................................. 83

Table 7-8 PCCK06B Copperfield Creek (downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs ............................................................................................................. 84

Table 7-9 PCCK21 Copperfield Creek (downstream) Summary Data (2010 to 2014) and ISSTVs ............................................................................................................................... 85

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Table 7-10 Descriptors of Impact Magnitude ....................................................................................... 87

Table 7-11 Threat Score Ranking ........................................................................................................ 88

Table 7-12 Threat Scores PCCK04 ..................................................................................................... 88

Table 7-13 Threat Scores PCPWD ...................................................................................................... 89



Table 7-16 Pine Creek Summary of Risks ........................................................................................... 91

Table 7-17 Copperfield Creek summary of risks .................................................................................. 93

Table 9-1 Recommendations Table ................................................................................................. 101

Figure index Figure 2-1 2013 to 2014 Rainfall ........................................................................................................... 7

Figure 2-2 PCPWD and PCCK06 Flow Rate 2014 ............................................................................... 8

Figure 2-3 PCPWDand PCCK06 Dilution Ratio 2014 ........................................................................... 9

Figure 2-4 PCPWDand PCCK06 Cumulative Volume 2014 ................................................................. 9

Figure 2-5 Surface Water Monitoring Locations .................................................................................. 11

Figure 2-6 Pine Creek pH .................................................................................................................... 14

Figure 2-7 Pine Creek Manganese ..................................................................................................... 15

Figure 2-8 Copperfield Creek pH ........................................................................................................ 16

Figure 2-9 Copperfield Creek lead concentrations.............................................................................. 16

Figure 2-10 Pine Creek Pits zinc concentrations (2010 to 2014) .......................................................... 17

Figure 2-11 Copperfield Creek zinc concentrations (2010 to 2014) ..................................................... 19

Figure 4-1 Copperfield Creek sediment % particle size distribution (June 2013) ............................... 37

Figure 4-2 Copperfield Creek sediment % particle size distribution (May 2014) ................................ 38

Figure 4-3 Pine Creek sediment % particle size distribution (June 2013) .......................................... 39

Figure 4-4 Pine Creek sediment % particle size distribution (May 2014) ........................................... 39

Figure 5-1 Marchant sub-sampler ....................................................................................................... 47

Figure 5-2 Variation in Abundance between sites and sampling occasions ....................................... 52

Figure 5-3 Variation in Taxa Richness between sites and sampling occasions ................................. 53

Figure 5-4 Variation in PET Richness between sites and sampling occasions .................................. 54

Figure 5-5 Variation in SIGNAL between sites and sampling occasions ............................................ 55

Figure 5-6 Variation in AUSRIVAS O/E50 between sites and sampling occasions ............................ 56

Figure 5-7 NMDS plot showing variation in community composition between samples from Control and Impact Sites collected between 2010 and 2014 ............................................ 58

Figure 5-8 NMDS plot showing variation in community composition between sampled collected during the period 2010 to 2014 .......................................................................... 58

Figure 6-1 PCPWD zinc concentrations .............................................................................................. 70

GHD | Report for Crocodile Gold - Pine Creek Project Area, 43/22192 | ix

Appendices Appendix A – WDL 166-02

Appendix B – Water Quality Data

Appendix C – Linear Regressions

GHD | Report for Crocodile Gold - Pine Creek Project Area, 43/22192 | 1

1. Introduction 1.1 Background

The Pine Creek Project Area (PCPA) lies within the Daly River catchment. The local sub-catchment systems are the ephemeral Pine Creek and Copperfield Creek which drain from the project area. Both streams flow into the Cullen River, a large tributary of the Douglas Daly River. The Daly River flows into the ocean, some 200 km west of the project area.

The PCPA is currently managed under a care and maintenance lease agreement. However, discharge water and its effects on the receiving environment are required to be managed by Crocodile Gold Australia Operations (CGAO).

Pine Creek Process Water Dam (PCPWD) drains to the south via a constructed concrete spillway and wooden weir which then discharges to an unnamed tributary of Copperfield Creek approximately 2 km downstream. The release of this waste water from the PCPWD to Copperfield Creek is currently controlled by the Waste Discharge License 166-02 pursuant to S74 of the Water Act.

Enterprise and South Gandy’s Pits are connected to Pine Creek by diversion channels and as a result each wet season there are passive flows of water from the pits to Pine Creek.

To provide information that can be used to manage the environmental impacts from discharge water entering Pine Creek and Copperfield Creek, CGAO have adopted an integrated multiple lines of evidence approach. This approach includes surface water, ecotoxicological, macroinvertebrate and sediment monitoring programs, the results of which are used to assess the potential impacts to aquatic ecosystems from discharges from PCPWD, Enterprise and Gandy’s Pits.

Site-specific issues addressed by this report include:

Current passive and future active management of PCPA waste water discharge from Pine Creek Process Water Dam (PCPWD) into Copperfield Creek as per WDL 166-02 Conditions.

Passive management of PCPA waste water discharge from South Gandy’s and Enterprise Pits.

Investigating the water quality of Pine and Copperfield creeks downstream of the discharge points for contaminant issues and assessment of creek health.

1.2 Waste Discharge Licence

The environmental water quality leaving the PCPA is managed by the current Waste Discharge Licence (WDL 166-02) which commenced on the 17 December 2012 and will expire on the 31 August 2014 (Appendix A).

WDL 166-02 provides the following qualitative discharge limits:

“Waste water(s) discharged from the authorised discharge points must not:

Contain any visible matter , floating oil and grease or petroleum hydrocarbon sheen, or litter or

other objectionable floating matter;

Cause or generate odours which would adversely affect the use of the surrounding waters;

Cause algal blooms;

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Cause visible change in the behaviour of fish or other aquatic organisms;

Cause mortality of fish or other aquatic organisms; or

Cause adverse impacts on plants”.

WDL 166-02 also includes the following requirements as relevant to this report:

“15. Surface water monitoring must be conducted in accordance with Appendix 1.

16. The Licensee must, at Monitoring Points PCCK06 and PCCK03 apply the interim site specific trigger values as listed in Table 4-5 of the Crocodile Gold Australia Operations Pine Creek Project Area 2011-2012 Monitoring Report and Appendix 1 of this Licence.

17. Sediment monitoring must be conducted in accordance with Appendix 2.

18. Biological monitoring must be conducted in accordance with Appendix 3 and the Biological Monitoring Environment Management Plan for Pine Creek Project Area 2012 dated 4 March 2012.

19. Ecotoxicological monitoring must be conducted in accordance with the Ecotoxicological Monitoring Plan for Pine Creek Project Area 2012 document dated 6 March 2012 ("the Ecotox Plan") or revisions approved in accordance with condition 20 of this Licence.”

This report also fulfils the requirements of the following WDL 166-02 Sections:

“28. The Licensee must provide to the Administering Agency a Monitoring Report, in accordance with the following schedule:

Reporting Period Report Submission at the end of:

December 2012 – October 2013 November 2013 November 2013 – July 2014 August 2014

29. The Monitoring Report must:

29.1 be prepared in accordance with the requirements for a Monitoring Report identified on pages 12-24 of the document: Guidelines for Reporting in Environmental Issues available from: http://www.nretas.nt.gov.au/data/assets/of file/0009/14031/consultants reporting environmental issues pdf, and

29.2 include a trend analysis and interpretation of monitoring results (field data and analytical parameters) required as a condition of this Licence.”

31. The Licensee must provide to the Administering Agency a minimum of 20 Business Days prior to the expiry date of this Licence a Licence Report.

The Licence Report must include:

31.1 results of the ecotoxicological monitoring program together with a detailed interpretation of the results; and

31.2 revised site specific trigger values including all supporting documentation that relates to the derivation of the trigger values.”

WDL166-02 also specifies that the operator adheres to the legislative requirements of the BUD (section 73 of the Act) and Environmental Protection Objectives (Part 4 of the WMPCA).

An Environment Protection Objective (EPO) is a statutory instrument to establish principles on which:

a) Environmental quality is to be maintained, enhanced, managed or protected;

b) Pollution, or environmental harm resulting from pollution, is to be assessed, prevented, reduced, controlled, rectified or cleaned up; and

c) Effective water management is to be implemented or evaluated.


1.3 Purpose of this Report

This Environmental Monitoring and WDL Licence Report fulfils the requirements of the following Sections of WDL 166-02: 16, 17, 18, 19, 28, 29 and 30 as listed above. This report has been prepared for Crocodile Gold Australia Operations for submission to the Northern Territory Environmental Protection Authority (NT EPA) to meet WDL 166-02 requirements.

1.4 Scope and Limitations

1.4.1 Scope

This Report provides CGAO with the following to meet the requirements of WDL 166-02:

Analysis and interpretation of CGAO monitoring data for the period of November 2013 - July 2014 and preparation of an environmental monitoring report for the Pine Creek Mine Site. This report:

– is prepared in accordance with the requirements for a Monitoring Report identified on pages 12-24 of the document: Guidelines for Reporting in Environmental Issues1 available from: http://www.nretas.nt.gov.au/data/assets/pdf_file/0009/14031/consultants_reporting_ environmental_issues_ pdf; and

– includes a trend analysis and interpretation of monitoring results (field data and analytical parameters) required as a condition of this WDL-166-02.

Preparation of a Licence Report for the reporting period of the licence (17 December 2012 and expiring 31 August 2014). Specifically including:

– results of the ecotoxicological monitoring program together with a detailed interpretation of the results; and

– revised site specific trigger values including all supporting documentation that relates to the derivation of the trigger values.

Provision of achievable recommendations to necessitate meeting future WDL conditions, revised SSTVs and improvement of water management strategies.

Revision and update of the risk assessment conducted in the ‘Pine Creek Project Area 2010-2012 Environmental Monitoring Report’ September 2012, by SKM on behalf of CGAO, adopting the CGAO risk assessment framework.

1.4.2 Limitations

This Crocodile Gold Australia Operations Environmental Monitoring and WDL Licence Report (“Report”):

Has been prepared by GHD Pty Ltd (“GHD”) for Crocodile Gold Australia Operations (CGAO) and the NT EPA.

May only be used and relied on by CGAO and the NT EPA.

Must not be copied to, used by, or relied on by any person other than CGAO without the prior written consent of GHD

May only be used for the purpose of addressing WDL 166-02 requirements (and must not be used for any other purpose).

GHD and its servants, employees and officers otherwise expressly disclaim responsibility to any person other than CGAO arising from or in connection with this Report.

1 GHD has prepared previous WDL reports using an alternative format to this guideline which still achieves the EPA

requirements.


To the maximum extent permitted by law, all implied warranties and conditions in relation to the services provided by GHD and the Report are excluded unless they are expressly stated to apply in this Report.

The services undertaken by GHD in connection with preparing this Report were limited to those specifically detailed in section 1.4 of this Report.

The opinions, conclusions and any recommendations in this Report are based on assumptions made by GHD when undertaking services and preparing the Report (“Assumptions”), including (but not limited to) those specified in section 1.5 below.

GHD expressly disclaims responsibility for any error in, or omission from, this Report arising from or in connection with any of the Assumptions being incorrect.

Subject to the paragraphs in this section of the Report, the opinions, conclusions and any recommendations in this Report are based on conditions encountered and information reviewed at the time of preparation and may be relied on until 6 months, after which time, GHD expressly disclaims responsibility for any error in, or omission from, this Report arising from or in connection with those opinions, conclusions and any recommendations.

1.5 Assumptions

In using the data provided by CGAO, it is assumed that appropriate quality assurance and quality control procedures have been applied in the sampling, analysis and reporting of data for all monitoring locations.

1.6 Data Sources

Relevant reports and data were provided by CGAO. These reports included the following:

CGAO 2010-2014 water quality data

CGAO 2013-2014 sediment quality data

CGAO 2013 Mine Management Plan

CGAO 2013 Ecotoxicology Monitoring Plan

CGAO Biological Monitoring Plan

CGAO Sediment Monitoring Plan

CGAO Surface Water Monitoring Plan

SKM (2012) Environmental Monitoring Report 2010-2012

ERISS Ecotoxicology Reports (2010-2011)

Ecotox Services Australasia Ecotoxicology Reports (2010 -2014)


2. Surface Water Quality 2.1 Introduction

Discharge from the PCPA is made up of active and passive discharges. Active discharge is water that is released to the environment as a direct result from CGAO management actions for example pumping or syphoning water into an offsite drainage system; Passive discharge is water that is released to the environment from the PCPA that CGAO has no management control over, for example stream flows resulting from rainfall received in the PCPA catchments. Pine Creek received passive discharges to the system, whilst Copperfield Creek received active discharges to the system during the November 2013 to July 2014 reporting period.

Throughout the PCPA CGAO has engineered water management systems in place to manage, mitigate and monitor the potential impacts that may be associated with adverse changes in surface water quality. The management of these potential impacts on this site ensure:

Downstream ecosystems are protected from the release of poor quality water.

Downstream ecosystems are protected from the release of fugitive sediment.

Fauna and riparian vegetation and groundwater users are protected by managing surface water quality.

Receiving waters, aquatic ecology and the beneficial values of the water resource are protected.

This Report assesses all water quality from 2010 to June 2014 supplied by CGAO. Where further interrogation of the data is required the 2013/14 wet season water quality data has been used to aid in interpretation.

It must be noted that the ISSTVs listed in Appendix 1 of WDL 166-02 only apply to sites PCCK03 and PCCK06 following ANZECC (2000) guidelines. SSTVs do not apply to standing water bodies or within mixing zones. CGAO apply the stock watering guidelines to site within mixing zones and standing water bodies.

2.2 Authorised Discharge Locations

The authorised PCPA discharge locations as specified in WDL166-02 are outlined in Table 2-1 below. PCPWD discharges into the Copperfield Creek system via active discharges, and PCCK04 discharges into the Pine Creek system via passive discharges.

Table 2-1 PCPA Authorised Discharge Points

Authorised Discharge Point Description Location

PCPWD Pine Creek Process Water Dam at the Weir Boards (MLN 13 Influences).

Latitude: -13.847 º

Longitude: 131.835º

PCCK04 Pine Creek MLN 13 Eastern Tenement Boundary. Downstream of Sth Gandy’s (MLN 1130) and Enterprise Pit (MLN 13).

Latitude: -13.819 º

Longitude: 131.827 º


The sources of waste waters from the Pine Creek Project Area originate from the legacy infrastructure associated with historical mining activity including waste rock dumps, heap leach pads, open pits, backfilled pits and a tailings dam as described in detail in CGAO MMP (2013). Table 2-2 shows the main sources of waste water to the receiving creeks.

Table 2-2 Waste Water Sources

Catchment Source Receiving Sites

Pine Creek Enterprise Pit Pine Creek via PCCK04, PCCK02, PCCK03

South Gandy’s Pit

Backfilled International Pit

NW WRD

Copperfield Creek Process Water Dam Copperfield Creek via PCPWD, PCCK06, PCCK06B, PCCK21

Tailings storage facility

Main WRD

Old Heap leach facility

The main contributing contaminant loads to the Pine Creek system originate from the NW WRD. The main contributing contaminant loads to the Copperfield Creek system originate from Pine Creek Process Water Dam (PCPWD) which is a repository of a number of sources, including the tailings dam, main WRD and the old heap leach pad.

2.3 Rainfall

Two rain gauges are located at the PCPA and monitored daily through the wet season months. One is located at the CGAO Pine Creek Village and the other at the Process Water Dam. During the current reporting period, maximum rainfall occurred during January 2014 for PCPWD and March 2014 for Pine Creek as shown in Figure 2-1. The majority of the waste water discharged from the PCPWD occurred during this peak rainfall period.


Figure 2-1 2013 to 2014 Rainfall

2.4 Volume of Water Discharged

Under direction from the DME, CGAO actively discharged waters from the PCPWD authorised discharge location commencing on 24 January 2014. This was undertaken to create storage capacity to capture recession flows within the PCPWD at the end of the wet season and prevent discharge occurring into the Copperfield Creek during recessional flows.

Table 2-3 and Table 2-4 summarises the volume of water released from PCPWD and the flow data of Copperfield Creek at PCCK06 (receiving environment) respectively. This data was obtained from automated height loggers installed at the sites during the reporting period and site rating tables.

Table 2-3 2013/14 PCPWD Discharge Data

2013-2014 PCPWD Discharge Data

Max flow rate 27.2 ML/day

Days of discharge 45 Days

Total discharge 402.5 ML

Average 8.9 ML/day

Monitoring period 14/01/2014 28/04/2014


Table 2-4 2013/14 PCCK06 Flow Data

2013-2014 PCCK06 Flow Data

Max flow rate 892 ML/day

Days of flow 86 Days

Total flow 9893 ML

Average 115 ML

Monitoring period 29/01/2014 25/04/2014

A total of 402.5 ML was discharged from PCPWD over a period of 45 days, the maximum discharge flow rate was 27.2 ML/day and the average was 8.9 ML/day, in comparison the maximum flow rate in Copperfield Creek was 892 ML/day and the average was 115 ML/day over the monitoring period. Figure 2-2 through to Figure 2-4 display the flow rates of PCCK06 and PCPWD, the cumulative volumes at the two sites and the ratio of PCPWD discharges to the flow rate at PCCK06.

Figure 2-2 PCPWD and PCCK06 Flow Rate 2014

As can be seen in Figure 2-2 the discharge rates from PCPWD were low throughout the wet season, whereas the flow measured at PCCK06 was relatively high, especially during February. The high flow at PCCK06 ensured sufficient dilution of the PCPWD discharge, thus minimising the effects of the discharge waters on the receiving environment.


Figure 2-3 PCPWDand PCCK06 Dilution Ratio 2014

The maximum dilution of PCPWD release water at PCCK06 was 100 percent for most of the wet season . Figure 2-3 illustrates that high dilution occurred during February and early March 2014. The average dilution occurring at PCCK06 during the 2013/14 wet season was 92.7 percent with a minimum dilution of 59 percent in early April 2014. Figure 2-3 highlights that the current method of discharge control at PCPWD is not sufficient to maintain a high dilution throughout the wet season. This is supported by the water quality data where PCCK06 often does not meet the SSTVs.

Figure 2-4 shows the cumulative volumes of releases from PCPWD compared to PCCK06, the volume released from PCPWD is significantly less than the volume that flowed past PCCK06 after early February 2014.

Figure 2-4 PCPWDand PCCK06 Cumulative Volume 2014

0

2000

4000

6000

8000

10000

12000

Volu

me

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Cumlative Volume

PWD Cumlative Volume PCCK06 Cumlative Volume


2.5 Surface Water Monitoring Program

Surface water monitoring requirements are specified in WDL 166-02. The results of this monitoring program are used to understand the influence of wastewater discharge from the project area to the receiving Pine Creek and Copperfield Creek systems. The monitoring program is designed to assist in identifying trends and to assist determining the success of the various surface water management measures. Surface water monitoring locations for the PCPA are shown in Table 2-5 and Figure 2-5. Each catchment incorporated the monitoring of the upstream location, discharge waters, downstream compliance site, and further downstream locations.

Analytes are shown in Table 2-6 and sampling frequencies are shown in WDL 166-02.

The reference site derived Interim Site Specific Trigger Values (ISSTVs) are to be applied in the assessment of monitoring data from the Copperfield Creek PCCK06 and the Pine Creek PCCK03 downstream sites, stipulated as per clause 16 the WDL166-02 for the 2013/14 water quality data.

#*#*

#*

#*

#*

#* #*

#*

Pine Creek

PCPWD

PCCK06

PCCK16

PCCK04

PCCK03

PCCK02PCCK01

PCCK06B

STUAR

T HIG

HW

AY

OLD

STUAR

T HIG

HW

AY

COPPERFIELD CREEK

805,000

805,000

810,000

810,000

8,465,

000

8,465,

000

8,470,

000

8,470,

000

Figure 2-5N:\AU\Darwin\Projects\43\22192\GIS\Maps\Deliverables\43_22192_001_WDL166_02_MonitoringLocations.mxd

0 0.5 1 1.5 2

Kilometres

LEGEND

© 2014. Whilst every care has been taken to prepare this map, GHD (and Crocodile Gold) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.

Job NumberRevision A

43-22192

Date 20 Aug 2014oCrocodile Gold Australia Pty LtdWDL Annual Reporting

WDL 166-02monitoring locations

Data source: Crocodile Gold, Mine infrastructure, tenements and sample locations, 2014; Geoscience Australia, Watercourse Lines, Roads. Created by:cwilson

Level 5 66 Smith Street Darwin NT 0800 Australia T 61 8 8982 0100 F 61 8 8981 1075 E [email protected] W www.ghd.com

Map Projection: Transverse MercatorHorizontal Datum: GDA 1994Grid: GDA 1994 MGA Zone 52

Paper Size A4

#* Water Quality Sample Sites

Watercourses

Mine lease

#* #*#*#*

#*#*#*#*

#*

Pine Creek

PCCK21


Table 2-5 Surface Water Monitoring Locations for WDL 166-02

Pine Creek Copperfield Creek

Site Code PCCK03 PCCK01 PCCK02 PCCK04 PCCK06 PCPWD PCCK06B PCCK16 PCCK21

Latitude -13.814° -13.817° -13.818° -13.819° -13.862° -13.847° -13.878° -13.862° -13.993°

Longitude 131.839° 131.810° 131.831° 131.827° 131.833° 131.834° 131.827° 131.820° 131.903°

Description One kilometre further downstream from PCCK02 at Railway line culvert, Pine Creek (compliance)

Pine Creek upstream of Green Valley Road (control)

Pine Creek u/s Main Terrace Crossing

WDL 166-02 Authorised discharge point within Pine Creek at tenement boundary MLN13.

100 m downstream of the confluence of Copperfield Creek with the process water dam spillway tributary (compliance)

Pine Creek Process Water Dam, WDL 166-02 Authorised discharge point.

Two kilometres further downstream of PCCK06

Copperfield Creek upstream of any mine site discharge at the Jindare/Umbrawarra Road Crossing (control).

Copperfield Creek – 20 kilometres downstream of discharge at location known as 'Blue Hole"

Table 2-6 Surface Water Monitoring Analytes for WDL 166-02

Type Analytes

Field measurements Flow, water level, pH, electrical conductivity, dissolved oxygen, temperature

Dissolved metals (0.45 µm) µg/L Aluminium, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, selenium, zinc

Environmental indicators mg/L Turbidity, total suspended solids, total dissolved solids, hardness, carbonate, bicarbonate, alkalinity, calcium, magnesium, potassium, sodium, chloride, sulphate


2.6 Surface Water Quality Results

This section discusses the historical water quality trends at the site from January 2010 to July 2014 as this time period captures the water quality on and off-site prior to meeting the requirements of WDL 166-02. Recent and historical data are also assessed where appropriate. Water quality associated with ISSTVs and ANZECC (2000) guidelines is discussed for sites PCCK03 and PCCK06. Summaries of water quality data are located in Appendix B.

2.6.1 Trend Analysis

All water quality data (January 2010 to July 2014) for each site was assessed using a simple linear regression with R2 analysis to determine the trend of the analyte concentration over time. Sites with an R2 value of >0.700 were considered to show a significant trend (i.e. there is a correlation between the analyte and time of sampling 70 percent of the time). Sites with significant and non-significant trends are shown in the Table 2-7 and Table 2-8 for each catchment. All linear regression trend analysis data are shown in Appendix C. Non-significant trends are also reported where appropriate. Significant trends are discussed further in each section.

2.6.2 Application of Site Specific Trigger Values

The 2013/14 ISSTVs as listed in WDL 166-02 have been used in this assessment of downstream water quality. The application and management actions of site specific trigger values is discussed in Section 3.6.

2.7 Pine Creek Water Quality Trends

Site PCCK01 is the background water quality site for comparison with the Pine Creek downstream sites PCCK02 and PCCK03. The results from this site have been used to determine the site specific trigger values (SSTVs) used for Pine Creek. The SSTV report is located in Section 3. All water quality data tables and graphs for Pine Creek and Copperfield Creek monitoring points are located in Appendix B.

Table 2-7 Pine Creek Trend Analysis (January 2010 to June 2014)

Site Analyte Trend R2

PCCK01 No significant trends

PCCK02 Alkalinity (total) Up 0.2976

Cadmium Down 0.2352

Chloride Up 0.2751

Cobalt Down 0.3151

Lead Down 0.2319

Manganese Down 0.2419

Potassium Down 0.2656

Sodium Down 0.2238

PCCK03 Iron Down 0.4570

Manganese Up 0.3894

Zinc Up 0.3950

PCCK04 pH Down 0.4069

Sodium Down 0.4483

Total alkalinity Down 0.2258


No significant trends were detected at any Pine Creek sites. The Pine Creek upstream site (PCCK01) did not show any significant or non-significant trends over the past 4.5 years.

The water quality at PCCK04 does show a non-significant downward trend for pH as results for April, May and June 2014 are below pH 6 (5.98, 5.88 and 5.58 respectively) (Figure 2-6). These sampling periods are the first to detect pH below 6.0 at this site. This downward trend may require additional monitoring of pH as previous dry season pH quality remained stable. The metal concentrations detected during the May 2014 (pH 5.88) sampling period did show an increase from the previous months as shown in Table 2-8.

It is interesting to note that non-significant downward trends for metals are evident at PCCK02, in contrast to PCCK04 and PCCK03 which shows non-significant upward trends for iron, manganese and zinc. Figure 2-7 shows the non-significant upward trends (PCCK03) and non-significant downward trends (PCCK02) for Manganese. The pH in Enterprise Pit in January 2014 was 5.86, however, this increased to 7.22 in June 2014. This may indicate that low pH is entering the system from another source.

Table 2-8 PCCK04 Metal and pH concentrations

Analyte February 2014 March 2014 April 2014 May 2014

pH 6.0 6.11 6.53 5.88

Aluminium µg/L 50 50 20 40

Cobalt µg/L 5 15 24 33

Iron µg/L 85 67 32 100

Manganese µg/L 180 440 800 1300

Nickel µg/L 7.0 13 19 29

Zinc µg/L 330 480 830 1200

Figure 2-6 Pine Creek pH


Figure 2-7 Pine Creek Manganese

2.8 Copperfield Creek Water Quality Trends

Site PCCK16 is the background water quality sites for comparison with the Copperfield Creek downstream sites PCCK06, PCCK06B and PCCK21. The results from this site have been used to determine the site specific trigger values (SSTVs) used for Copperfield Creek. The SSTV report is located in Section 3. All water quality data tables and graphs for Pine Creek and Copperfield Creeks monitoring points are located in Appendix B.

Table 2-9 Copperfield Creek Trend Analysis (January 2010 to June 2014)

Site Analyte Trend R2

PCCK06 No significant trends

PCCK06B No significant trends

PCCK16 Magnesium Up 0.1273

PCCK21 pH Down 0.2623

PCPWD pH Up 0.5140

Aluminium Down 0.2729

Cadmium Down 0.2442

Cobalt Down 0.2156

Copper Down 0.2072

Lead Down 0.5803

Nickel Down 0.1726

Zinc Down 0.1571


No significant or non-significant trends were observed in water quality at PCCK06 or PCCK06B in the 2010-2014 data. The Copperfield Creek upstream site PCCK16 did show a non-significant upward trend for magnesium, indicating that this analyte is naturally fluctuating in the catchment as it is not influenced by the historical Pine Creek mining activities.

The far downstream site shows a non-significant downward trend for pH, however, this seems unrelated to the PCPWD discharge as sites PCCK06 and PCCK06B do not show the same trend and PCPWD shows a non-significant upward trend. Figure 2-8 shows the non-significant upward trend at PCPWD since 2010.

Due to the increase in pH reducing the bioavailability of metals by changing the speciation, a series of non-significant downward trends is detected in metals as shown in Table 2-8. Figure 2-10 shows the decrease in lead concentrations at PCPWD since 2010.

Figure 2-8 Copperfield Creek pH

Figure 2-9 Copperfield Creek lead concentrations


2.9 SSTV Exceedances 2013/14

As discussed previously the ISSTVs listed in WDL 166-02 are applied to the downstream sites on Pine Creek (PCCK03) and Copperfield Creek (PCCK06) during the reporting period November 2013 to July 2014. The Management procedures for exceedances of ISSTVs is located in CGAO MMP (2013) and summarised in Section 3.6. It is important to note that ISSTVs do not apply to other sampling sites in the catchments particularly standing water bodies such as PCPWD or within mixing zones such as PCCK02.

2.9.1 PCCK03

During the 2013/14 monitoring period all analytes were within or below the ISSTVs listed in WDL 166-02 with the exception of zinc. Zinc exceeded the ISSTV of 31 µg/L on all sampling occasions with a median concentration of 290 µg/L and a maximum of 590 µg/L recorded in April 2014. These concentrations do have potential to impact sensitive species as discussed in Section 3. However, this site is beneath a rail culvert which has the potential to contribute metals to the system and confound the water quality results. Zinc concentrations at PCCK02 are also elevated, so it may be possible that the zinc concentrations at PCCK03 originated from the water quality at PCCK04. Zinc was below the stock watering guidelines (SWG) on all sampling occasions.

Gandy’s Pit and Enterprise Pit contribute to the water flow at PCCK04 and Figure 2-10 shows that there is a slight upward trend in the zinc concentrations in Enterprise Pit while Gandy’s Pit shows a non-significant downward trend. Water quality summaries of both these sites are located in Appendix B.

Figure 2-10 Pine Creek Pits zinc concentrations (2010 to 2014)

2.9.2 PCCK06

During the 2013/14 monitoring period all analytes with the exception of electrical conductivity, cadmium and zinc were below the 2013/14 ISSTVs for PCCK06 as listed in WDL 166-02. These exceedances are discussed below and shown in Table 2-9.


Table 2-10 PCCK06 Exceedances (January 2014 to June 2014)

Date Electrical Conductivity µS/cm

Cadmium µg/L Zinc µ/L

ISSTV 250 0.8 95

26/01/14 <ISSTV 1.0 980

03/02/14 <ISSTV <ISSTV 900

09/02/14 <ISSTV <ISSTV 1100

16/02/14 <ISSTV <ISSTV 370

24/02/14 <ISSTV 1.6 1,100

02/03/14 <ISSTV 1.1 770

09/03/14 298 2.1 1,400

10/03/14 285 NT NT

16/03/14 <ISSTV 1.2 890

02/04/14 397 NT NT

03/04/14 490 NT NT

06/04/14 <ISSTV <ISSTV 130

*NT: Not tested

Electrical Conductivity

Electrical conductivity (EC) exceeded the 2013/14 ISSTV of 250 µS/cm on four occasions, twice in March 2014 and twice in April 2014. These exceedances occurred on consecutive days and the EC returned to below the ISSTV the next day. EC at the levels measured in March and April are unlikely to cause adverse environmental harm to the receiving ecosystem. Anecdotal evidence from Ecotox Services (Dr R. Krassoi pers. comm.) shows that the sensitive cladoceran (Ceriodaphnia dubia) reproduction bioassay is not adversely impacted by EC below 3,500 µS/cm.

Cadmium

Cadmium exceeded the 2013/14 ISSTVs on four consecutive occasions from 24 February to the 16 March 2014. These four exceedances do trigger management action Level 3 (CGAO MMP 2013 and listed in Section 3.6 below), however, the concentrations of cadmium detected are unlikely to cause adverse environmental harm as no observed effect concentration (NOEC) ranges as listed in ANZECC (2000), modified for hardness, range from 1.3 µg/L to 8.6 µg/L. PCPWD contributes to the concentration of cadmium detected at PCCK06 as cadmium is not detected at the upstream site, PCCK16.


Zinc

Zinc exceeded the 2013/14 ISSTV on seven consecutive occasions from 3 February to 16 March 2014, thus triggering a Level 3 management action. Zinc is present in the water during this time does have the potential to cause adverse environmental harm to aquatic organisms living in the receiving water at PCCK06, as evidenced by the ecotoxicology testing discussed in Section 6. Zinc was below the SWG on all occasions. PCPWD contributes to the concentration of zinc detected at PCCK06 as the upstream site PCCK16 does not show elevated zinc levels.

Discussion

The results of the 2013/14 monitoring program show that overall the water quality has improved as the 2012/13 results for PCCK06 detected copper and nickel above the ISSTVs, whereas, the 2013/14 period showed these metals were below the ISSTVs. This may be due to the reduction in metals in PCPWD over the last few years. The mean zinc concentration reported in CGAO MMP (2013) for PCCK06 was 122 µg/L, whereas the median zinc concentration for 2013/14 was 58.5 µg/L (Table 2-11). Figure 2-11 shows the variability in zinc concentrations and non-significant downward trend at PCPWD since 2010.

Figure 2-11 Copperfield Creek zinc concentrations (2010 to 2014)


Table 2-11 PCCK06 Water Quality (January 2010 to June 2014)

Analyte Upper ISSTV

Lower ISSTV

Count Minimum Median Maximum

pH 7.5 6 70 4.31 6.38 7.04

EC µS/cm 250 20 70 42 187 734

Dissolved Oxygen % 120 35 48 69 114 142

Aluminium µg/L 590 - 24 5 30 550

Arsenic µg/L 140 - 24 0.5 1.0 62

Cadmium µg/L 0.8 - 24 0.05 0.05 2.1

Cobalt µg/L - - 24 0.5 0.75 30

Chromium µg/L 40 - 24 0.5 0.5 0.5

Copper µg/L 2.5 - 24 0.5 0.5 4.0

Iron µg/L - - 24 71 425 1500

Lead µg/L 9.4 - 24 0.5 0.5 1.0

Manganese µg/L 3600 - 24 17 61 1000

Nickel µg/L 17 - 24 0.5 1.5 21

Zinc µg/L 95 - 24 9 59 1400


2.10 Conclusions

2.10.1 General

No significant trends were observed for any analytes at any sites. This is due to the variability of water quality at each site caused by the wet/dry season changes in water quality/quantity. However, by assessing all data since 2010, the general trends can be detected and these were discussed in each section.

2.10.2 Copperfield Creek

Surface water quality monitoring at PCPWD shows that an increase in pH is occurring with a non-significant upward trend and the resulting decrease in bioavailable metals since 2010. However, cadmium and zinc concentrations downstream at PCCK06 do exceed the 2013/14 ISSTV. This is a reduction from the previous year’s results which showed copper and nickel also exceeding the ISSTVs. Concentrations of zinc at PCCK06 are sufficient to cause adverse environmental harm to aquatic organisms.

The water chemistry results show that PCCK06 and PCCK06B are within the mixing zone of the PCPWD discharge as the PCCK06 site is only 100 m downstream of the confluence of the PCPWD spillway tributary and Copperfield Creek. Even though Copperfield Creek provides dilution during discharge, it is insufficient at PCCK06 and PCCK06B to allow these sites to meet the ISSTV for zinc. However, all other ISSTVs are met at PCCK06B, therefore PCCK06B may be a better location for the WDL compliance point to meet the 2014/15 SSTVs. However, this site has access issues and better control of the PCPWD discharge will allow the SSTVs to be met at PCCK06.

Management of the discharge from PCPWD requires investigation and the incorporation of a system that will allow better control of the flow to enable the dilution factors for environmental protection to be met downstream in Copperfield Creek is required.

2.10.3 Pine Creek

Surface water quality monitoring at PCCK04 showed a slight decrease in pH and concentrations of zinc at PCCK03 higher than the ISSTV on all sampling occasions during the 2013/14 wet season. All other analytes were below the ISSTV at PCCK03. Care must be taken when interpreting PCCK03 data as the rail crossing, Stuart Highway and Pine Creek community may influence water quality at the site.

2.11 Recommendations

Based on the conclusions above the following changes are recommended for water management at the Pine Creek Project Area:

2.1 The Copperfield Creek 2014/15 compliance point retained at PCCK06, with improved discharge management at PCPWD to enable the SSTVs to be met at PCCK06.

2.2 A mixing zone study to confirm and validate the location of the Copperfield Creek compliance point.



2.5. Investigate a monitoring site downstream from PCCK03.

2.6. Investigate the source of the decrease in pH at PCCK04.


3. Site Specific Trigger Values 2014/15 3.1 Introduction

The Site Specific Trigger Values (SSTVs) derived for CGAO’s Pine Creek Project Area for the wet season 2014/15 follows the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC 2000). These guidelines form part of Australia’s National Water Quality Management Strategy. The primary objective of the guideline is “to provide an authoritative guide for setting water quality objectives required to sustain current or likely future, environmental values [uses] for natural and semi-natural water resources in Australia and New Zealand”.

ANZECC (2000) specifically states Guidelines “are not meant to be applied directly to recycled water quality, contaminant levels in discharges from industry, mixing zones, or stormwater quality”. Instead, they should be applied to waters outside of these areas, with consideration given to the system inputs including type and condition.

Trigger values are an early warning mechanism to provide insight into potential adverse water quality changes, they are not intended to be an instrument to assess ‘compliance’ and should not be used in this capacity (Appendix 7: ANZECC 2000). Trigger values are designed for environmental protection and are to be met at the edge of the mixing zone. The SSTVs calculated in this document are to be applied to the Pine Creek downstream monitoring point PCCK03 and the Copperfield Creek monitoring site PCCK06.

3.1.1 Need for Trigger Values

Discharge from mining activities potentially contains a range of compounds and elements that could have a detrimental impact on the receiving environment. Once the concentrations of each of these chemicals are known, it is necessary to assess their impact by comparing them to relevant trigger values for ecosystem protection. Trigger values may be derived from:

ANZECC (2000) default values

Licence limits

Site specific values

Local ecotoxicity testing

The ANZECC (2000) Guidelines define trigger values as:

“… the concentrations (or loads) of the key performance indicators measured for the ecosystem, below which there exists a low risk that adverse biological (ecological) effects will occur. They indicate a risk of impact if exceeded and should ‘trigger’ some action, either further ecosystem specific investigations or implementation of management/remedial actions.” (ANZECC [2000], Volume 1, Appendix 1).

3.2 Sites used for SSTV Calculation

Pine Creek, at PCCK04, receives water from South Gandy’s Pit and Enterprise Pit. Copperfield Creek at PCCK06 includes inputs from Copperfield Dam and Pine Creek Process Water Dam (PCPWD). These inputs will impact on water quality at the mine lease boundary. Therefore, upstream sites that are applicable for use as background water quality are:

Pine Creek (PCCK01)

Copperfield Creek (PCCK16)


Table 3-1 Surface Water Monitoring Sites used in this SSTV

Pine Creek Upstream Copperfield Creek Upstream

Site PCCK01 PCCK16

MGA East 803839 804801

MGA North 8470765 8465732

3.3 Data Provided by CGAO

CGAO has provided water quality data for the sites listed in Table 3-1 obtained from the Surface Water Monitoring Program. The two locations are shown in Figure 2-5.

The data from the sites shown in this document are representative of the background environment of Pine Creek and Copperfield Creek. Upstream conditions on the creek system have been used to establish baseline water quality and current environmental conditions at these locations.

A summary of the water quality data is presented in Appendix B.

3.4 Beneficial Uses

A Declaration of Beneficial Uses and Objectives for the Copperfield Creek was gazetted on the 11th of June 1997. It lists the following areas and uses:

Drinking Water: (upstream of Zone 52 Australian Map Grid point 804650E 8465660N (1:50,000 Topo Map Series R722, Sheet 5270 - II, Edition 1 - AAS).

Aquatic Ecosystem Protection: (downstream of above reference point).

3.5 Aquatic Ecosystem Trigger Values

3.5.1 Derivation of Site Specific Trigger Values

The SSTVs in this Report have been derived on the basis of the ANZECC (2000) Guidelines procedure and CGAO Mine Management Plan (2013). The process is to calculate a series of different percentiles for different parameters as follows:

For physicochemical parameters – 20th and/or 80th percentile

For nutrients and non-toxic compounds – 80th percentile

For metals – 80th percentile

Then compare the:

ANZECC (2000) default trigger values for freshwater ecosystems and toxicants in freshwaters.

Reliable background level (80th percentile) of parameters at the chosen reference sites.

The reference sites chosen to derive the site specific trigger values for Pine Creek is PCCK01 located upstream from South Gandy Pit and Enterprise Pit. The reference sites chosen to derive the site specific trigger values for Copperfield Creek is PCCK16 located upstream from the Pine Creek Process Water Dam PCPWD as shown in Figure 2-5.

The highest value is selected as the trigger value, though for metals, if the background conditions are equal to or higher than the published trigger value or when no trigger value exists, then the 80th

percentile of the data set has been adopted as the trigger value (ANZECC (2000), Section 8.3.5.5, Volume 2).


3.5.2 Data Requirements – Chemicals and Seasonal Variation

A good understanding of the ambient water quality and its seasonal variations is a critical part of any environmental assessment study. The background data collected has included each chemical that may be present in the pit and dam waters and may enter the environment. This is of particular importance when natural background concentrations of these chemicals are high as may be the case in mineralised mining environments. In this case the water quality data includes all the analytes listed in Appendix 1 Surface Water Monitoring Program of the WDL 166-02.

The ANZECC Guidelines (2000) recommend that, for the purpose of deriving ambient values and site specific trigger values, a sufficient amount of data needs to be collected and that it should characterise seasonal variations:

“A minimum of two years of continuous monthly data at the reference site is required before a valid trigger value can be established. “ (Volume 1, Section 7.4.4.1).

The guidelines recommend the use of filtered (or dissolved) metal samples as a conservative approach to estimating the concentration of the indicator. This allows for better estimation of the presence of metals in their bioavailable form (Section 7.4.2).

ANZECC (2000) Default Trigger Values

For ecosystems that can be classified as highly disturbed, the 95 percent species protection trigger values may still apply. However, it could be appropriate to apply a less stringent guideline trigger value such as 90 or 80 percent protection level. This depends largely on the state of the ecosystem, water management goals and the approval of the NT EPA. For developing site specific trigger values for the Pine Creek Project Area, in order to not contribute to the disturbed nature of the system and to work towards continual improvement of the system, the protection levels have been set in WDL 166-02 at 80 percent due to the legacy of historical mining and current water quality in the area.

Within the ANZECC (2000) guidelines, Pine Creek and Copperfield Creek fall into different categories depending on the parameter reviewed as outlined in Table 3-2. Both Creeks fall within both the highland and low land rivers and stream categories due to their elevations. However, for the purpose of calculating the SSTVs both creeks have been designated as lowland rivers.

Table 3-2 ANZECC (2000) Categorisation of Pine Creek and Copperfield Creek

Parameter ANZECC Category

Physicochemical Aquatic Ecosystem Protection, “Lowland Rivers for NT”, (ANZECC (2000), Table 8.2.8 to 8.2.12).

Nutrients Aquatic Ecosystem Protection, “Lowland Rivers of NT”, (ANZECC (2000), Tables 8.2.2 to 8.2.7).

Metals and toxicants “Freshwater” category (ANZECC (2000), Table 3.4.1), with 80 percent species protection for highly disturbed ecosystems being considered as appropriate.


Ecosystem Conditions: For metals, it is considered that the ecosystem conditions which apply to the site are those of highly disturbed systems as prescribed in WDL166-02.

High and Low Reliability Trigger Values: High reliability trigger values have been be preferred in this Report as low reliability values are obtained from an incomplete data set2, however some low reliability values have been used where data is not sufficient to develop site specific trigger values e.g. chromium.

3.5.3 Data Validation

All available data collected to date has been considered in the determination of ambient conditions and the assessment of trigger values.

The 20th percentiles and 80th percentiles have been calculated for the derivation of site specific trigger values.

3.5.4 Data Below Limit of Reporting

When the analytical result is below the LOR for a particular chemical species, then a value of half the detection limit has been included in the calculation. This is one of the recommended approaches by the Water Quality Monitoring and Reporting Guidelines (ANZECC (2000b), Section 6.2.1). It is also understood that this approach has limitations, in particular, when over 25 percent of the data is below the detection limit (BDL). Where greater than 25 percent of values in a background dataset are below the detection limit the ANZECC (2000) default trigger value has been selected as the site specific trigger value (SSTV).

3.5.5 Hardness Modified Trigger Values

The ANZECC (2000) guidelines require the trigger values for several metals to be corrected for hardness to account for the hardness of the local water. The metals which fall in to this category are cadmium, chromium (iii), copper, lead, nickel and zinc. The SSTV may be modified for hardness using the 80th percentile hardness value for the downstream Copperfield Creek site (PCCK06) and the Pine Creek site (PCCK03) monitoring locations if required.

3.6 SSTV Exceedance Management

For parameters that exceed the 2014/45 SSTVs at the downstream monitoring location for Copperfield Creek (PCCK06) and the Pine Creek downstream site (PCCK03), the actions described in the CGAO MMP (2013) are implemented for physico-chemical stressors and for toxicants and these are summarised in Table 3-4.

2 For toxicants two types of triggers exist, high reliability trigger values and low reliability trigger values. These are defined as

follows: “High Reliability Trigger Value – Trigger values that have a higher degree of confidence because they are from an adequate set of chronic toxicity data. Low Reliability Trigger Value – Trigger values that have a low degree of confidence because they are derived from an incomplete data set. They are derived using either assessment factors or from modelled data using statistical method. They should only be used as interim indicative working levels.” (ANZECC & ARMCANZ, Volume 1, Appendix 1).


Table 3-3 2014/15 SSTV exceedance management actions (CGAO MMP 2013)

Trigger Level Corrective Action Internal Reporting Requirements

External Reporting Requirements

Focus (SSTV) and default trigger (80%) Aquatic Water Guidelines

Manage by routine procedures.

Manage at team level.

No action required.

No action required.

Action Level 1 (outside of default or SSTV value, on two sampling occasion).

Internal response required to assess discharge management

Manage through routine procedures

Report to CGAO Environmental Manager.

No action required.

Action Level 2 (outside of default or SSTV value, on three sampling occasions).

Internal response required to alter discharges and prevent further exceedances.

Investigation source of toxicants.

Manage through routine procedures.

Report to CGAO Environmental Manager.

Immediately (within 12 hours) notify the EPA and the DME.

Action Level 3 (outside ANZECC SWG). Unauthorised discharge, loss of previously contained waste water.

Cease wastewater discharges required to rectify within compliance ASAP. Follow up Investigation.

Event/Hazard/ Incident/Injury Report to be completed Report to CGAO management team.

Report to EPA and DME as an incident.


3.7 Results and Discussion

3.7.1 Gap Analysis

A gap analysis has been performed on the data provided by CGAO for sites PCCK01 and PCCK16. The amount of water quality data provided by CGAO is shown in Table 3-4 to provide a minimum of 24 months of data. A summary of the water quality data is located in Appendix B. SSTVs are based on data from the Pine Creek upstream monitoring site PCCK01 and from the Copperfield Creek upstream monitoring site PCCK16.

Table 3-4 Water Quality Data

Site Number of Samples (physico-chem)

Number of Samples (Metals)

Dates

PCCK01 49 - 64 27 July 2012 to June 2014

PCCK16 81 -112 51 July 2012 to June 2014

Table 3-5 shows the hardness data for sites PCCK03 and PCCK06 which have been used to apply the hardness correction factor as discussed in Section 3.5.5.

Table 3-5 Hardness Data for PCCK03 and PCCK06 (2012 to 2014)

Hardness (CaCO3) mg/L

PCCK03 PCCK06

Number 10 127

Minimum 28 2.5

Median 56 11

Maximum 130 400

80th Percentile 111 (Moderate) 36 (Soft)

3.7.2 2014/15 Wet Season Site Specific Trigger Values

From the data shown in Table 3-6, all analytes have sufficient data to generate SSTVs. The data in Table 3-6 shows the upstream Pine Creek water quality at PCCK01 and the data in Table 3-7 shows the upstream Copperfield Creek water quality at PCCK16. The analytes presented in Table 3-6 and those listed in WDL 166-02 that have trigger values listed in ANZECC (2000).


Table 3-6 Pine Creek PCCK01 Statistical Summary (July 2012 to June 2014)

Analyte N Min Median Max 20th

Percentile 80th

Percentile

pH 63 5.99 6.48 7.40 6.16 6.84

Electrical Conductivity µS/cm 64 25.4 40.5 91.2 34.4 61.6

Dissolved Oxygen % 49 17.3 79.7 162 55.4 110

Turbidity NTU 20 6.3 22 63 15 38.2

Total Suspended Solids mg/L 21 <5 <5 31 <5 9.0

Total Dissolved Solids mg/L 57 14.3 25.4 54.6 21.6 36.3

Calcium mg/L 27 <0.5 0.5 0.28 <0.5 0.88

Potassium mg/L 27 1.0 1.7 3.5 1.2 2.2

Sodium mg/L 27 0.25 3.7 6.8 2.7 4.7

Magnesium mg/L 27 0.25 0.8 1.4 0.6 1.1

Bicarbonate mg/L 30 9.0 16 26 14 23.2

Carbonate mg/L 30 0.5 2.5 2.5 2.5 2.5

Total alkalinity mg/L 30 9.0 16 26 14 23.2

Sulphate mg/L 33 0.5 0.5 6.0 0.5 0.5

Chloride mg/L 33 0.5 4.0 7.0 2.0 4.6

Hardness mg/L 26 1.5 4.0 9.0 3.0 7.0

Dissolved Metals

Aluminium µg/L 26 15 38 300 20 240

Arsenic (total) µg/L 26 <1.0 1.5 7.0 <1.0 3.0

Cadmium µg/L 26 <0.1 <0.1 <0.1 <0.1 <0.1

Chromium µg/L 23 <1 <1 <1 <1 <1

Cobalt µg/L 26 <1 <1 2.0 <1 <1

Copper µg/L 26 <1 <1 11 <1 2.0

Iron µg/L 26 200 460 2500 360 610

Lead µg/L 26 <1 <1 4.0 <1 <1

Manganese µg/L 26 11 18 120 12 26

Nickel µg/L 26 <1 <1 <1 <1 <1

Selenium µg/L 9 <1 <1 <1 <1 <1

Zinc µg/L 26 <1 2.0 26 <1 6.0


Table 3-7 Copperfield Creek PCCK16 Statistical Summary (July 2012 to June 2014)

Analyte N Min Median Max 20th

Percentile 80th

Percentile

pH 110 5.82 6.51 7.1 6.21 6.72

Electrical Conductivity µS/cm 112 6.5 49 327 34 59

Dissolved Oxygen % 81 6.5 108 148 64 121

Turbidity NTU 28 1.3 7.1 41 3.5 11

Total Suspended Solids mg/L 50 <5 <5 38 <5 9.4

Total Dissolved Solids mg/L 110 16.9 29.9 2665 22.7 36.4

Calcium mg/L 54 0.25 0.9 2.5 0.6 1.2

Potassium mg/L 54 1.3 1.8 3.2 1.5 2.3

Sodium mg/L 54 3 4.8 17 3.9 6.1

Magnesium mg/L 54 0.7 1.4 5.4 1 1.6

Bicarbonate mg/L 51 2.5 23 62 15 26

Carbonate mg/L 51 2.5 2.5 14 2.5 2.5

Total alkalinity mg/L 51 2.5 23 62 15 26

Sulphate mg/L 51 0.5 0.5 35 0.5 0.5

Chloride mg/L 51 1.0 2 8 2 4.0

Hardness mg/L 54 3.0 8 28 6 9.4

Dissolved Metals

Aluminium µg/L 51 5.0 25 370 5 67

Arsenic (total) µg/L 51 <1 <1 5 <1 <1

Cadmium µg/L 51 <0.1 <0.1 0.1 <0.1 <0.1

Chromium µg/L 50 <1 <1 <1 <1 <1

Cobalt µg/L 51 <1 <1 <1 <1 <1

Copper µg/L 51 <1 <1 1 <1 <1

Iron µg/L 51 190 460 2000 320 730

Lead µg/L 51 <1 <1 <1 <1 <1

Manganese µg/L 51 2.5 16 54 9 22

Nickel µg/L 51 <1 <1 <1 <1 <1

Selenium µg/L 35 <1 <1 <1 <1 <1

Zinc µg/L 51 <1 3 55 <1 9

The ANZECC (2000) default guidelines are exceeded by the 80th percentile results for turbidity, iron and aluminium at site PCCK01 and for iron at PCCK16, most likely due to the mineralised geology of the area and impacts of rainfall run-off. Therefore, it may not be appropriate to apply the default guidelines for these analytes to the downstream sites.


3.8 Selection of 2014/2015 Site Specific Trigger Values

The values shown in Table 3-6 were used to derive SSTVs for the parameters listed in WDL 166-02 as described in Section 3.5.1. The selected SSTVs for the 2014/15 wet season to be applied to PCCK03 and PCCK06 are shown in Table 3-8.

The SSTV calculated for cobalt is the moderate reliability 95 percent species protection trigger value listed in ANZECC (2000) Section 8.3.7 of 90 µg/L, due to the low anomalous value that is used for the low reliability trigger value.

All analytes without SSTVs and not shown in Table 3-8 are those analytes without references in ANZECC (2000). SSTVs have not been determined for those analytes as the likelihood of chronic toxicity at the concentrations detected at PCCK03 and PCCK06 is low.

Table 3-8 Calculation of the 2014/2015 Wet Season SSTVs

Analyte 80th

Percentile

PCCK01

80th

Percentile

PCCK16

ANZECC 80% TVs

SSTV PCCK03

SSTV PCCK06

pH 6.84 6.72 8.0 8.0 8.0

pH (20th %ile) 6.16 6.21 6.0 6.0 6.0

Electrical conductivity µS/cm 61.6 59 250 250 250

Dissolved Oxygen % 110 121 120 120 120

Dissolved oxygen % (20th %ile) 55 64 85 55 64

Turbidity NTU 38.2 11 15 38.2 15

Total suspended solids mg/L 9.0 9.4 20 20 20

Dissolved Metals

Aluminium µg/L 240 67 150 240 150

Arsenic (total) µg/L 3.0 <1 140 140 140

Cadmium µg/L <0.1 <0.1 0.8 (2.16**) 2.16 0.8

Chromium µg/L*** <1 <1 40 40 40

Cobalt µg/L <1 <1 90# 90 90

Copper µg/L 2.0 <1 2.5 (6.25**) 6.25 2.5

Iron µg/L 610 730 300* 610 730

Lead µg/L <1 <1 9.4 (37.6**) 37.6 9.4

Manganese µg/L 26 22 3600 3600 3600

Nickel µg/L <1 <1 17 (42.5**) 42.5 17

Selenium µg/L*** <1 <1 34 34 34

Zinc µg/L 6.0 9 31 (77.5**) 77.5 31

* Low reliability trigger values (ANZECC 2000. Chapter 8.3.7) ** Hardness modified *** Recommended for removal from WDL Appendix 1 analytical suite # Moderate reliability trigger value


3.9 Conclusions

Sufficient data was available of appropriate quality to calculate site specific trigger values for Pine Creek and Copperfield Creek for the 2014/15 wet season. The high background levels of iron, aluminium, turbidity and the low background of dissolved oxygen have all been taken into account in the calculation of the SSTVs. Hardness correction factors were applied to cadmium, copper, lead, nickel and zinc at PCCK03 using the 80th percentile of hardness at that site.

From the water quality data, the monitoring sites PCCK03 and PCCK06 are within the mixing zone of their respective discharges as the SSTVs are routinely exceeded. SSTVs are applied to the edge of the mixing zone where background concentrations are expected to be met. Active controlled management of discharges may be required to calculate the required volume to be discharged (particularly from PCPWD) to meet the dilution factor calculated in Section 6 and the mixing zone can then be accurately determined.

3.10 Recommendations

Based on the conclusions above, the following are recommended:

3.1. Update the SSTVs on an annual basis.

3.2. Determine the mixing zone for Pine Creek and Copperfield Creek to determine appropriate monitoring locations to meet the SSTVs.

3.3. Controlled discharges to enable SSTVs to be met at downstream monitoring sites.


4. Sediment Quality 4.1 Introduction

WDL 166-02 requires the Pine Creek Project Area (PCPA) to be assessed for sediment quality. The purpose of the sediment monitoring program is to improve the understanding of the impacts of Copperfield and Pine Creeks from PCPA wastewater discharged and to ensure compliance with WDL 166-02.

4.2 Sediment Monitoring Program

CGAO has developed a Sediment Monitoring Program for the Pine Creek Project Area for 2012-2013.

The sediment monitoring program includes sampling from four sites within Pine Creek and five sites within Copperfield Creek. The selection of sites was based on the WDL requirements. The sampling sites are aligned with the WDL defined surface water and aquatic fauna monitoring sites.

Table 4-1 Sediment Monitoring Program

Site Code Description

Pine Creek

PCCK01 Pine Creek upstream of Green Valley Road (control).

PCCK02 Pine Creek upstream of Main Terrace Crossing, downstream of discharge.

PCCK03 One kilometre further downstream from PCCK02 at Railway line culvert, Pine Creek.

PCCK04 Pine Creek authorised discharge point downstream of Sth Gandy’s and Enterprise Pit.

Copperfield Creek

PCCK16 Copperfield Creek upstream of any mine site discharge at the Jindare/Umbrawarra Road Crossing (control).

PCPWD Copperfield Creek Discharge Point.

PCCK06 100 metres downstream of the confluence of Copperfield Creek with the process water dam spillway tributary.

PCCK06B Copperfield Creek – approximately 3 kilometres downstream of the confluence with the process water spillway tributary.

PCCK21 Copperfield Creek – approximately 20 kilometres downstream of discharge at a location known as “blue hole”.

Sampling for all sediment monitoring sites occurred at the end of the wet season in 2013 (10/06/2013) and 2014 (04/05/2014, 24/05/2014 and 24/07/2014) and included analysis of parameters as shown below Table 4-2.


Table 4-2 Sediment Monitoring Frequency and Parameters

Frequency Sediment Analysis Parameters

Annual at end of wet season

Particle Size analysis, % moisture, saturated pH, TOC

2 mm size fraction 1 M HCl metal digest, Total digest metals (Al, As, Cd, Co, Cu, Fe, Mn, Ni, U, Zn) , total sulphur, sulphate, sulfide.

2 mm size fraction acid volatile sulfate (AVS) + simultaneous extracted metals (SEM) on selected metals only (Cd, Cu, Pb, Hg, Ni, Zn).

4.3 Sediment Quality Results

4.3.1 Sediment Metals Analysis

Sediment metal quality results were analysed by a NATA accredited laboratory. Bioavailable metals data (from 1M HCl dilute acid digestion analysis) have been assessed against the ANZECC (2000) Interim Soil Quality Guidelines (ISQG). A summary of metals results from 2013 and 2014 are provided in Table 4-3 (Copperfield Creek) and Table 4-4 (Pine Creek).

Copperfield Creek

The concentration of bioavailable metals from the discharge point (PCPWD) exceeded the low ISQG for arsenic in 2014 and the high ISQG for zinc in 2013 and 2014 as shown in Table 4-3.

The concentration of bioavailable metals at PCCK06B did not exceed the ISQG, with the exception of zinc which exceeded the high ISQG in 2014. The concentrations of bioavailable zinc from the same site in 2013 were below the low ISQG. The sediments at site PCCK06 did not exceed any low ISQG in 2013 or 2014, this is likely due to the high percentage of large particle sizes at PCCK06 limiting binding and adsorption sites.

All remaining sediment samples from Copperfield Creek sample locations in 2013 and 2014 had bioavailable metal concentrations below the low ISQG.

The elevated zinc levels at PCCK06B cannot be solely attributed to the PCPWD discharge as concentrations detected upstream of PCCK06B at PCCK06 (and downstream of the discharge point) were consistently lower than the concentrations detected at PCCK06B. This suggests that there are additional background sources of zinc contamination impacting Copperfield Creek at PCCK06B or this could be related to the differences in particle sizes between the sites.

All sample locations including the control site PCCK16 upstream of mine site discharge, showed an increase in concentrations of bioavailable metals between 2013 and 2104.

Pine Creek

The concentration of bioavailable metals at PCCK04, Pine Creek authorised discharge point downstream of South Gandy’s and Enterprise Pit exceeded the low ISQG for zinc and cadmium in 2014 as shown in Table 4-4. Concentrations of bioavailable zinc at PCCK03, 1 km downstream from PCCK02 at the railway line culvert in Pine Creek, also exceeded the ISQG low trigger value for zinc in 2014. The concentration of bioavailable zinc from the discharge point PCCK04 and downstream site PCCK03 were below the ISQG low trigger values in 2013.

Sample site PCCK02 immediately downstream of PCCK04 and upstream of PCCK03 did not have sediment samples exceeding the zinc ISQG trigger values in 2013 or 2014. Therefore the zinc concentrations detected at PCCK03 may not be attributed to the mine source.


No exceedances of cadmium or other metal low ISQGs were seen in downstream sites.

It cannot be confirmed at this stage, but it is possible that there is an additional source of contaminants from the railway line at PCCK03 causing the increase in bioavailable zinc between PCCK02 and PCCK03. It is not possible to relate the elevated zinc levels from PCCK03 to the discharge as levels were higher than at the discharge point and were not detected at elevated levels at PCCK02.

Similarly to Copperfield Creek, the Pine Creek sampling locations also showed an increase in concentrations of bioavailable metals between 2013 and 2014.


Table 4-3 Copperfield Creek Bioavailable Sediment Metals Amnalysis Summary (1 M HCL in mg/kg dry weight) compared to ANZECC Guidelines

Parameter Unit ISQG (low-high

trigger values)

PCCK16 (Control) PCPWD PCCK06 PCCK06B PCCK21

10/06/2013 4/05/2014 10/06/2013 24/07/2014 10/06/2013 4/05/2014 10/06/2013 29/05/2014 10/06/2013 4/05/2014

Aluminium mg/kg N/A 160 230 750 1,100 230 330 370 610 150 390

Arsenic mg/kg 20 - 70 <4 <4 1 26 <4 <4 <4 <4 <4 12

Cadmium mg/kg 1.5 - 10 <0.5 <0.5 3 2 <0.5 <0.5 <0.5 1 <0.5 <0.5

Cobalt mg/kg N/A <1 3 13 8 1 3 7 38 2 1

Chromium mg/kg 80 - 370 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Copper mg/kg 65 - 270 <1 2 <1 7 18 5 12 23 18 7

Iron mg/kg N/A 680 3,800 530 1,200 770 1,500 870 3,500 770 2,000

Lead mg/kg 50 - 220 3 5 22 30 6 7 6 9 6 10

Manganese mg/kg N/A 18 51 130 100 39 91 94 840 39 40

Nickel mg/kg 21 - 52 <1 <1 4 5 1 <1 2 8 <1 <1

Zinc mg/kg 200 - 410 <1 2 980 670 2 28 140 430 19 13

Bold denotes exceedance of low ISQG trigger values Bold and Highlight denotes exceedance of high ISQG trigger value


Table 4-4 Pine Creek Sediment Bioavailable Metals Analysis Summary (1 M HCL in mg/kg dry weight) compared to ANZECC guidelines

Parameter Unit ISQG (low-high)

PCCK01 PCCK04 Discharge Point PCCK02 PCCK03

10/06/2013 4/05/2014 10/06/2013 4/05/2014 10/06/2013 4/05/2014 10/06/2013 4/05/2014

Aluminium mg/kg N/A 94 830 430 490 220 2,000 760 240

Arsenic mg/kg 20 - 70 9 9 10 14 <4 13 18 5

Cadmium mg/kg 1.5 - 10 <0.5 <0.5 <0.5 <0.5 <0.5 2 <0.5 <0.5

Cobalt mg/kg N/A 1 <1 11 4 6 12 44 <1

Chromium mg/kg 80 - 370 <1 <1 <1 <1 <1 <1 <1 <1

Copper mg/kg 65 - 270 18 9 10 10 4 35 10 2

Iron mg/kg N/A 770 3,500 930 1,400 660 1,400 1,200 600

Lead mg/kg 50 - 220 6 13 33 36 20 49 22 10

Manganese mg/kg N/A 39 35 140 53 120 180 1,000 31

Nickel mg/kg 21 - 52 <1 <1 3 2 1 9 10 1

Zinc mg/kg 200 - 410 2 7 130 77 52 350 210 49

Bold denotes exceedance of low ISQG trigger values Bold and Highlight denotes exceedance of high ISQG trigger value


4.3.2 Sediment Particle Size, pH and TOC

Results of sediment analysis for particle size, pH, sulphur, sulphate and total organic carbon (TOC) are shown in Table 4-5 (Copperfield Creek) and Table 4-6 (Pine Creek).

Copperfield Creek

Sediments from Copperfield Creek are predominately coarse comprising mostly of gravel and coarse sand the exception is sediments from sample location PCCK21. The sediments from site PCCK21 in 2013 and 2014 contained significantly lower percentages of gravel and coarse sand and higher portions of fine sand and silt. Sample location PCCK06 in 2014 also had sediments with a lower portion of gravel and coarse sands.

TOC content of the sediments do not appear to show a trend between upstream and downstream sites. TOC in sediments in 2014 were notably higher than 2013 which is likely to be related to the higher level of small particle sizes in the sediments in 2014. Sediments with higher levels of organics have a greater capacity to adsorb and bind metals.

Concentrations of sulphur and sulphate in sediments were considered low with the exception of the discharge location. Results showed some variability between sites and sampling years.

pH of sediments ranged from 5.1 to 6.4. The pH showed some variability between sites and sample years, however there were no notable trends in sediment pH.

Figure 4-1 Copperfield Creek sediment % particle size distribution (June 2013)


Figure 4-2 Copperfield Creek sediment % particle size distribution (May 2014)

Pine Creek

Sediments from Pine Creek in 2013 Figure 4-3 were predominately coarse comprised mostly of gravel and coarse sand. In contrast, the sediments from Pine Creek in 2014 (Figure 4-4), contained a significantly higher portion of finer sediments and less coarse sediments. This was particularly notable at the upstream site PCCK01.

TOC content of the sediments do not appear to show a trend between upstream and downstream sites. Similarly to the Copperfield Creek sediments, TOC in sediments in 2014 were notably higher than 2013. Sediments with higher levels of organics have a greater capacity to adsorb and bind metals, thus reducing the bioavailability.

Concentrations of sulphur and sulphate show a slight increasing trend between upstream control (PCCK01) and the downstream sites. The sulphur and sulphate concentrations from the discharge point are quite low. Sediments from downstream sites PCCK02 and PCCK03 contained the highest levels of sulphur and sulphate. Concentrations at these sites were higher than from the discharge location indicating that sources other than from the discharge point contribute to the sulphate levels downstream.

pH of sediments ranged from 5.5 to 6.1. The pH showed some variability between sites and sample years, however there were no notable trends in Pine Creek sediment pH levels.


Figure 4-3 Pine Creek sediment % particle size distribution (June 2013)

Figure 4-4 Pine Creek sediment % particle size distribution (May 2014)


Table 4-5 Copperfield Creek Sediment Analysis Summary – pH, TOC, sulphate, sulphur and particle size

PCCK16 (Control)

PCPWD (Discharge Point)

PCCK06 PCCK06B PCCK21

10/06/2013 4/05/2014 10/06/2013 24/07/2014 10/06/2013 4/05/2014 10/06/2013 29/05/2014 10/06/2013 4/05/2014

pH 5.1 6.4 6.3 5.4 5.8 5.5 5.8 6.4 5.6 6.1

TOC % 0.285 0.87 0.76 1.9 0.31 0.575 0.485 1.45 0.195 1.05

Sulphate mg/kg <2 <10 600 560 10 10 25 10 7 10

Sulphur mg/kg 11 20 2,100 2,100 36 30 65 70 19 60

Particle Size Distribution

Gravel >2.36 mm % 28.8 14.5 N/A N/A 56.7 3.4 31.3 39.8 0.2 0.4

Very coarse sand 1.18-2.36 mm % 22.8 23.3 N/A N/A 9.1 3.1 11.7 12 0.8 0.5

Coarse Sand 0.6-1.18 mm % 23.5 26 N/A N/A 7.3 5.2 20.1 9.6 7 1.1

Medium Sand 0.3-0.6 mm % 13.1 11 N/A N/A 7.2 13.3 18.3 13.2 49.7 8.5

Fine Sand 0.15 mm - 0.3 mm % 4.3 6.2 N/A N/A 3.7 18.3 7.9 7 20.3 21

Very Fine Sand 0.075-0.15 mm % 4.2 3.7 N/A N/A 10.1 14.1 6.3 2.9 9.8 17.9

Coarse Silt 0.075-0.02 mm % 1 10.5 N/A N/A 1.5 15.1 1.2 8.3 3.8 20.4

Fine Silt 0.002-0.2 mm % 1.5 5.4 N/A N/A 2.4 11.2 1.3 3.6 7.1 13.4

Clay <0.002 mm % 0.8 0.1 N/A N/A 2 16.2 1.9 6.6 1.3 16.9


Table 4-6 Pine Creek sediment analysis summary –pH, TOC, sulphate, sulphur, and particle size

PCCK01 PCCK04 (Discharge Point)

PCCK02 PCCK03

10/06/2013 4/05/2014 10/06/2013 4/05/2014 10/06/2013 29/05/2014 10/06/2013 4/05/2014

pH 6 5.5 5.9 6.1 5.1 6.0 6.0 6.0

TOC % 0.15 1.5 0.31 0.35 0.795 0.225 1.9 0.62

Sulphate mg/kg <2 <10 85 52 160 34 120 88

Sulphur mg/kg 18 70 65 69 160 47 430 70

Particle Size Distribution

Gravel >2.36 mm % 37.1 5.8 61.6 23.1 10.1 45 3.1 2.2

Very coarse sand 1.18-2.36 mm % 20.1 2 9.7 5.9 4.7 18.2 2 2.3

Coarse Sand 0.6-1.18 mm % 18.3 2 4.5 8.3 6.4 13.3 2.5 3.9

Medium Sand 0.3-0.6 mm % 14.9 2.6 2.9 10.9 15.1 9.2 19.2 10.7

Fine Sand 0.15 mm - 0.3 mm % 4.1 4.7 1.4 7.6 19.6 3.8 33.8 22.6

Very Fine Sand 0.075-0.15 mm % 3.2 11.6 12.7 15.7 11.4 5.8 11.6 24.9

Coarse Silt 0.075-0.02 mm % 1.1 21.8 1.1 12.5 10.7 0.6 8.3 15.6

Fine Silt 0.002-0.2 mm % 1.1 19.1 4.1 6.8 10.1 2.5 7 6.5

Clay <0.002 mm % 0.1 30.4 2 9.2 11.9 1.6 12.5 11.4


4.4 Historical Results

Recent results have been reviewed against the historical results from the 2010-2012 Pine Creek Project Area Monitoring Report (SKM 2012).

Copperfield Creek

The concentrations of bioavailable zinc at Copperfield Creek PCCK06B in 2014 were consistent with the 2010-2012 results. Concentrations exceeded the low ISQG in 2012 (310 mg/kg) and the high ISQG in 2014 (430 mg/kg). As noted in Section 4.3.1 bioavailable zinc concentrations in 2013 (140 mg/kg) were below the low ISQG, suggesting that metals in sediments have varied between years and are not increasing over time.

Discharge location PCPWD was not assessed in 2010-2012 and therefore historical results are not available to compare.

Similarly to 2010-2012 results, there is a slight increasing trend in sulphur and sulphate levels from the upstream site (PCCK16) to the downstream sites.

Pine Creek

2010-2012 results for PCCK02 identified an exceedance of the lead ISQG. No such exceedances were observed in 2013 or 2014. Total lead levels from PCCK04 and downstream sites PCCK02 and PCCK03 were sometimes above low ISQGs in 2013 and 2014, however bioavailable lead levels in sediments in 2013 and 2014 were well below the low ISQG at all sample locations.

Sample locations PCCK03 and PCCK04 were not assessed in 2010-2012 and therefore historical results are not available to compare.

Similarly to the 2010-2012 result, an increasing trend in sulphate and sulphur was observed at Pine Creek sediment sampling locations.

4.5 Conclusions

The sediment analysis results demonstrate that there is an increase in bioavailable zinc concentrations downstream of discharges in both Copperfield Creek and Pine Creek. The source of zinc causing the observed exceedances however is not able to be solely linked to the mine discharges as there is evidence to suggest additional sources of metal contamination between the discharge locations and downstream sites.

The results indicate that there is likely to be a toxic impact within the immediate vicinity of Copperfield Creek Discharge (PCPWD), however the observed effects are likely to be restricted to the immediate discharge zone. A lesser effect may be seen at PCCK04 based on the zinc concentrations. These conclusions are supported by the results of the ecotoxicity tests discussed in Section 6.

Pine Creek sediments show a lower metal load than the Copperfield Creek Sediments, possibly due to the large particle sizes recorded in Pine Creek sediments, but also related to the poorer water quality discharged from PCPWD. The results of future sampling programs should investigate the removal of Pine Creek from the sediment monitoring program and determine if the sediment monitoring program inn Copperfield Creek is providing information that is useful for managing the discharge from PCPWD.

Sediment monitoring at the Copperfield Creek sites would provide useful information for determining any changes to sediment chemistry if new discharge options are applied to the PCPWD discharge point.


4.6 Recommendations


4.2 Consideration could be given to removing the requirement for total metals analysis in sediment analysis. The total metals analysis does not add significant value to environmental impact interpretation process, as the ANZECC ISQGs are based on bioavailable metals.



5. Biological Monitoring 5.1 Biological Monitoring Program

Under WDL 166-02, CGAO are required to carry out biological monitoring annually prior to cessation of creek flows at the end of the wet season in order to assess if releases of mine affected water have resulted in any significant pollution impacts on aquatic ecosystem values. The core component of biological monitoring carried out by CGAO to date has been macroinvertebrate community monitoring.

Aquatic macroinvertebrates are small aquatic fauna without backbones and include insects (larval and adults), crustaceans (e.g. crabs, shrimp, prawns), molluscs (bivalves and gastropods), as well as worms and sponges, among others. Macroinvertebrates are used widely for the biological assessment of rivers and other waterways. The popularity of macroinvertebrates in ecosystem disturbance studies stems from:

Their abundance and diversity.

Ease of sampling.

A relatively good understanding of their taxonomy and ecological requirements.

Their sensitivity to changes in water quality, flow regime and habitat conditions and that there is a spectrum in terms of sensitivity to these factors among different taxa represented within a community.

Their lifespans (6 months to 2 years) are long enough to detect short to medium term changes in water quality and for recovery from those impacts to be monitored effectively.

Community structure, at any one time, represents an integrated response to a variation in water quality, such that they can provide an indication of responses of the aquatic ecosystem to water pollution even when acute, short-term changes in water quality are missed as a part of routine water quality monitoring.

One disadvantage of macroinvertebrates as indicators of river health is that it can be difficult to attribute shifts in community composition and abundances solely to anthropogenic impacts because natural changes (such as climatic factors) and natural variability in habitat between sites or variation in microhabitat sampled between sites can also influence macroinvertebrate community structure (MDBC 2004). The other issue is that their application can be somewhat limited in ephemeral streams (Batley et al. 2003); the nature of many streams around the study area, including those monitored as part of the PCPA WDL requirements. Ephemeral streams are characterised by long dry spells, followed by shorter periods of inundation. This high variability potentially complicates biomonitoring, with many factors other than mining impacts likely to play an important role in the distribution of macroinvertebrate communities. Macroinvertebrate recolonisation pathways and dynamics also play an important role, with these limited by location/s, type and quality of macroinvertebrate recolonisation sources. Successful recolonisation within ephemeral creeks is then limited by the quality and quantity of available habitat, water quality, time of the year and physical limitations of each macroinvertebrate taxa, amongst other factors (Smith et al. 2004).

Despite these disadvantages, macroinvertebrate communities currently represent the most ideal ecosystem component to assess potential impacts of water pollution that involves a number of different potential stressors (e.g. mine affected release water, which may be subject to reduced pH, increased electrical conductivity and increased concentrations of bioavailable metals compared to background conditions in the receiving water).


5.2 Study Design and History

CGAO has undertaken macroinvertebrate monitoring in the PCPA since 2009 in order to assess the general condition of the condition of Pine and Copperfield Creeks downstream of the release points and to detect any environmental impacts over time, as well as the success of particular management actions by CGAO aimed at improving ecological condition.

Macroinvertebrates have predominantly been monitored at six sites within the Pine Creek Sub-catchment system, apart from in 2009, only three sites were sampled, and in 2013, when seven sites were sampled. Apart from those years, the study design has involved the sampling of two Control sites (upstream inflow sites) and four Impact sites (downstream of discharge locations), as shown in Table 5-1 below and Figure 2-5.

Apart from the obvious change in sampling effort between 2009 and 2010, Impact site PCCK06B was introduced in 2010 and was sampled between that year and 2013. Although still a part of the WDL 166-02, it was not sampled in 20143. A new Impact site, PCCK03, was introduced under WDL 166-02. This has only been sampled in 2013 and 2014.

Table 5-1 Biological Monitoring Locations and Sampling History

Site Code Treatment Description

2009

2010

2011

2012

2013

2014

PCCK01 Control Pine Creek (upstream of Green Valley Road).

PCCK02 Impact Pine Creek upstream of Main Terrace Crossing.

PCCK03 Impact One kilometre downstream of Pine Creek project area at railway crossing location.

PCCK06 Impact 100 metres downstream of the confluence of Copperfield Creek with the process water dam spillway tributary.

PCCK06B Impact Copperfield Creek – 3 kilometres downstream of the confluence with Process Water Dam spillway tributary.

PCCK16 Control Copperfield Creek upstream of any mine discharge at Jindare/Umbrawarra Road Crossing.

PCCK21 Impact Copperfield Creek – 20 kilometres downstream of discharge at location known as ‘BlueHole’.

3 PCCK06B was unable to be sampled during 2014 due to access issues 4 The 2014 sample was taken 100 m downstream due to access issues


5.3 Sampling and Sample Processing Methods

5.3.1 Collection Methods

Sampling has routinely been conducted in the post-wet season recessional flow period so as to capture the potential effects of mine site runoff during the preceding wet season. The timing of sampling has generally been in early to mid-May, but in 2012, sampling was undertaken in late April following an intense period of rainfall. The latter was thought to be responsible for the low diversity and abundance of macroinvertebrates from samples collected that year (SKM 2012)

Macroinvertebrate samples for the CGAO WMP have consistently been collected in accordance with the NT AUSRIVAS (Australian Rivers Assessment System) protocols. AUSRIVAS is a rapid prediction system used to assess the biological health of Australian rivers. AUSRIVAS protocols for sampling ensure that the temporal and spatial analyses are comparable amongst sites through repeatable and consistent sampling techniques. The AUSRIVAS model compares collected fauna to fauna predicted to occur at the site in the absence of environmental impacts such as pollution.

The Darwin-Daly AUSRIVAS Early-Family-Edge Habitat model (Lamche, 2007) was selected as the appropriate model for data analysis during this study due to

the locality of the study area

the timing of the surveys in the early dry season

the family level identification applied

the fact that edge habitat was sampled.

NT AUSRIVAS sampling protocols involve the collection of a sample by disturbing the substrate, benthos and overlying habitat using a three-pronged rake and then capturing organisms via a 250 μm mesh dip net that is swept through the water column in the area adjacent the area disturbed by the rake. Where possible the edge habitat sampling is carried out near vertical banks which contained root material in pools where adjacent water velocity is minimal.

Once collected, the samples were washed through 10 mm and 250 µm mesh sieves. The course mesh sieve was examined for large, conspicuous taxa, and these were placed in the labelled sample container. The sample collected in the fine mesh sieve was also placed in the labelled sample container and filled with 70 percent ethanol. All samples were sent to the laboratory for further processing and macroinvertebrate identification.

Environmental variables were also recorded at each site in accordance with NT AUSRIVAS protocols (Lamche, 2007). Habitat variables measured included flow and water quality as well as a description of the riparian zone and geomorphology at each site.

5.3.2 Sample Processing Methods

Each sample collected was registered into GHD’s sample registration system and allocated a unique identifying number.

Samples were washed through a series of sieves (10 mm, 500 µm and 250 µm mesh sizes). Any large, conspicuous taxa identified in the 10 mm mesh sieve were added to the contents of the large mesh fraction retained in the field. The contents of the 500 µm mesh sieve were retained for macroinvertebrate identification and enumeration, while the 250 µm fraction was retained as sample residue for quality assurance purposes. The contents of the 500 µm mesh fraction were poured into a Marchant sub-sampler (Marchant, 1989; Figure 5-1) and extractions made randomly from cells (aliquots) in this apparatus. These extractions were placed under a microscope and the taxa identified and counted. This process continued until either all aliquots were examined or a total of 200 individuals had been counted and identified.


Records were also kept of the number of aliquots required to be processed in order to obtain a minimum 200 individual sub-sample so that relative abundances of each taxa present could be determined. Leica MZ9.5 stereo-dissection microscopes with planachromat objectives and a zoom capability between 6.3x and 60x were used to examine specimens. An Olympus BX40 compound microscope with zoom capabilities between 100x and 1,000x magnification was used for smaller taxa that required greater magnification.

Taxa were identified to family level, where possible, with the exception of key taxa identified in Lamche (2007) as either requiring identification to sub-family level (e.g. Chironomidae) or only to order level (e.g. Acarina). All taxa have been identified using the keys specified in Hawking (2000). Following identification, raw taxa counts were recorded in MS Excel and samples preserved and archived by GHD.

Figure 5-1 Marchant sub-sampler

5.4 7.2.3 Data Analysis

There is no single macroinvertebrate community metric that can be used to assess and/or quantify the influence of anthropogenic activities on macroinvertebrate communities. Responses to pollution can result in anything from changes in abundance and diversity through to changes in community composition through the loss or reduction of sensitive taxa and their replacement by more tolerant taxa. As such, a multiple lines of evidence approach is generally adopted with regards to interpreting macroinvertebrate community data.

The macroinvertebrate data collected as part of this project were analysed using a combination of univariate and multivariate statistical techniques. Univariate metrics provided an indication of ‘health’, while multivariate analysis focusses on variability in community composition between sites and sampling occasions. This is described in more detail in the section below.

5.4.1 Data Supplied

Macroinvertebrate data were supplied by CGAO for the purpose of this study. GHD undertook macroinvertebrate sample processing and indices generation for CGAO in 2013 and 2014, but in the period 2009 to 2012, these tasks were undertaken by other consultants. Hence, GHD does not take responsibility for any errors in the 2009 to 2012 data sets supplied by CGAO5.

5 In the end, only the 2010 to 2014 data sets were submitted to GHD. 2009 data are not included as part of the data analysis for

this report.


Data were collated into a single, coherent, data set covering the 2010 to 2014 temporal period. Some modifications to the 2010 to 2012 data were required as part of the data collation process. These included:

Allocating sub-orders Oribatida and Hydracarina to order Acarina to align with data collected in 2013 and 2014.

Pooling adult and larvae count data for families Dytiscidae and Hydrophilidae that had been separated in data collected from 2010 to 2012.

Assigning taxa to updated taxonomic groups (e.g. for the freshwater crab, Parathelphusidae were reassigned to the new taxonomic grouping, Sundatelphusidae).

These actions could potentially result in some subtle differences between results presented in previous reports and this study.

5.4.2 Univariate Analyses

Table 5-2 provides a summary of the univariate macroinvertebrate indices assessed as part of this study and, where relevant, a description of how to interpret results relating to those indices. It should be pointed out that, while Lamche (2007) cautions against the use of the SIGNAL index for assessing the status of Northern Territory macroinvertebrate communities, in our view the relative abundance of pollution-sensitive versus pollution-tolerant species still provides some insight as to the level of stress the macroinvertebrate community is being subject to, so this measure is considered appropriate for this study. It was also a metric reported in previous studies, so has been adopted for the sake of consistently.

Once generated, metrics were graphed and were also analysed using a Two-way Analysis of Variance (ANOVA). For the latter, data from individual sites for a given year were used as replicates for Control and Impact site sample groups for that year. This is because the sampling method used involved the collection of a single sample at each site. As a result, these analyses have a low statistical power and, therefore, results should be interpreted with caution.

Note also that abundance data was Log (x + 1) transformed prior to analysis in order to meet the assumptions of ANOVA, which requires that the data be as close to normally distributed as possible. Transformations were not necessary for the other univariate metrics.


Table 5-2 Macroinvertebrate Indices used as part of this Assessment

Macroinvertebrate Index

Description

Abundance The total number of individual taxa observed at each site. Generally increased abundance can be taken to mean better conditions and increased access to habitat and food resources. However, high abundances can also occur under degraded conditions where pollution-tolerant taxa proliferate. Hence, abundance is a measure that must be interpreted with caution and in context with other metrics and community composition data. Abundance was calculated based on the multiplication of raw abundance data by the inverse of the proportion of sample processed.

Taxa Richness The total number of taxa present at each site is a direct measure of diversity. It assumes that a high number of taxa within a site indicate that the various water quality, habitat and food requirements of taxa have been met (though this could also occur through anthropogenic effects that increase food or habitat supply). A negative environmental impact would normally result in the loss of taxa and a decline in Taxa Richness at a site.

PET Richness PET Richness was calculated as the total number of families from three orders of macroinvertebrates; Ephemeroptera (mayflies); Plecoptera (stoneflies); and Trichoptera (caddisflies). PET taxa include taxa that are very sensitive to disturbance (though some have moderate tolerances to pollution). Higher numbers of PET taxa indicate are generally taken to indicate a lower level of disturbance.

SIGNAL SIGNAL is biotic index that allocates a value to each macroinvertebrate family based upon their sensitivity to pollution. A macroinvertebrate family with a value of 10 indicates high sensitivity whilst a value of 1 indicates high pollution tolerance (Chessman, 1995). SIGNAL scores were then used to grade water quality into the following categories:

Signal Score > 6: Healthy Habitat

Signal Score 5-6: Mild Pollution

Signal Score 4-5: Moderate Pollution

Signal Score <4: Severe Pollution

AUSRIVAS O/E50 and Bandings

AUSRIVAS modelling assesses macroinvertebrate community condition based on the observed range of macroinvertebrate families versus that expected based on samples collected from ‘reference’ condition stream habitat in the same defined geographic area. This is described in more detail below.


The AUSRIVAS model is a predictive system that uses macroinvertebrates to assess the biological health of rivers in the Darwin-Daly Region (Lamche 2007). AUSRIVAS uses site-specific predictions of the macroinvertebrate fauna expected to be present in the absence of environmental stress. The expected (E) fauna from reference sites with similar sets of predictor variables (physical and chemical characteristics which cannot be influenced due to human activities, e.g. altitude) are then compared to the observed (O) fauna that were actually collected at a given site and the ratio derived is then used to indicate the extent of any impact. Both O and E measures relate to macroinvertebrates that have a predicted probability greater than 50 percent of occurring at the site if it is in reference condition. Hence, the critical metric in the AUSRIVAS model is called O/E50. The O/E50 ratio can range from zero, when none of the expected taxa are found at a site, to one, when all the expected taxa are found. Values greater than one are achieved when more families are found at the site than predicted by the model. The scores derived from the model can be placed in bands delineated by the Monitoring River Health Initiative (Table 5-3), which allows assessment of the level of environmental health at a site.

Table 5-3 Key to O/E50 AUSRIVAS Scores and Bands

Band O/E50 Upper Limit Band Description

Band X Infinite Macroinvertebrate assemblage is more biologically diverse than reference sites.

Band A 1.18 Site is in reference condition with most/all of the expected families found.

Band B 0.81 Site is significantly impaired, indicating a potential impact either on water quality and/or habitat quality which has resulted in a loss of taxa.

Band C 0.44 Site is severely impaired; indicating a loss of biodiversity due to substantial impacts on water and/or habitat quality.

Band D 0.7 Site is extremely impaired; few expected taxa remain, indicating extremely poor water and/or habitat quality resulting in a highly degraded waterway.

5.4.3 Multivariate Analyses

The multivariate analysis methods used to assess macroinvertebrate data included:

Non-metric Multi-Dimensional Scaling (NMDS) Ordination

PERMANOVA

Similarity Percentage (SIMPER)

All the above multivariate analyses were performed using PRIMER version 6.1.6. Prior to analysis, data were square root transformed in order to reduce the biasing influence of rare as well as abundant taxa on results. Note that this approach differs from the approach used by SKM (2012) whereby relative abundance data were subject to a fourth root transformation prior to analysis. That approach was not replicated here as the fourth root transformation is an overly severe data transformation. Hence, there is a possibility that these differences may contribute to differences in community composition results between this study and that by SKM (2012).


NMDS Ordination provides a representation of the relative similarity of entities (i.e. site samples) based on their attributes (i.e. macroinvertebrate community composition) within a reduced dimensional space. The more similar sites are to each other, the closer they are located in the NMDS ordination space. In this study, NMDS plots were used to display the similarity between Treatments (Impacted and Control) and Years (sampling events). A similarity matrix for all pairs of samples based on the Bray-Curtis similarity coefficient was calculated. Stress, which is a measure of the distortion produced by compressing multi-dimensional data into a reduced set of dimensions, was used to gauge how reliable the patterns presented in two dimensional NMDS plots are. Stress levels above 0.20 indicate a poor representation of inter-sample similarity and, as such, the NMDS results with stress values of this order require interpretation with caution.

The PERMANOVA procedure was used to compare macroinvertebrate taxonomic composition between sample groups. This procedure is the multivariate equivalent of an analysis of variance (ANOVA) procedure for univariate data. PERMANOVA was used to determine whether there were any differences in taxonomic composition between Treatments and between Years and to test for Treatment by Year effects. As was the case for ANOVA, data from individual sites for a given year were used as replicates for Control and Impact site sample groups for that year. As a result, these analyses have a low statistical power and, therefore, results should be interpreted with caution.

The SIMPER routine was used to identify taxa that contributed most to the average dissimilarity between Control and Impact site groups. SIMPER computes the average dissimilarity (Bray-Curtis) between all pairs of inter-group samples (every sample in group 1 with every sample in group 2 etc.) and then breaks this average down into the separate contributions from each taxon. In addition to calculating the average dissimilarity between groups, SIMPER also calculates the average similarity within a group. More importantly, SIMPER highlights the relative contributions of individual taxa to dissimilarity between treatment groups.


5.5 Biological Monitoring Results

5.5.1 Abundance

Figure 5-2 shows the variation in macroinvertebrate Abundance between sites and sampling occasions. Of note is the particular high abundances recorded in 2013, which are an order of magnitude or so greater than that recorded on other sampling occasions. Low abundances of macroinvertebrates were collected at all sites in 2012 and in 2014.

In the period between 2010 and 2012, the highest abundance was recorded from one of the control sites (either PCCK01 or PCCK16). In 2013 and 2014, however, abundance was highest at Impact sites PCCK06B and PCCK21 respectively. Results of a Two-way ANOVA presented in Figure 5-2 show that there was no significant difference in mean abundance between Control and Impact treatment group samples, but that there was a significant variation in mean abundance according to year. While not shown here, further investigation based on least-square-mean plots show that the significant ‘Year’ effect was caused mainly by significantly higher mean abundance in 2013 compared to that for 2012 and 2014.

Figure 5-2 Variation in Abundance between sites and sampling occasions

* Note that site PCCK03 was not sampled from 2010 to 2012 and site PCCK06B was not sampled in 2010 or 2014. Also, abundances associated with PCCK02 in 2012 and PCCK03 in 2014 are too low to be seen clearly based on the scale used in this graph

Table 5-4 Results of Two-Way ANOVA comparing Abundance between

Treatments and Sampling Occasions (years). Values in red indicate a significant effect

Effect SS df MS F p

Intercept 139.8741 1 139.8741 1146.291 0.000

Treatment 0.2156 1 0.2156 1.767 0.200

Year 8.0682 4 2.0171 16.530 0.000

Treatment*Year 0.7093 4 0.1773 1.453 0.255

Error 2.3184 19 0.1220


5.5.2 Taxa Richness

Figure 5-3 shows the variation in macroinvertebrate Taxa Richness between sites and sampling occasions. Of particular note is the low Taxa Richness values recorded at all sites in 2012, where the maximum Taxa Richness recorded was only 13 while the lowest was 2. At all sites other than PCCK21, the Taxa Richness recorded in 2014 was low compared to other years (except 2012). 2012 was the only year in which the highest Taxa Richness value was recorded from a Control site.

Results of a Two-way ANOVA presented in Figure 5-3 show that there was no significant difference in mean Taxa Richness between Control and Impact treatment group samples, but that there was a significant variation in mean Taxa Richness according to year. While not shown here, further investigation based on least-square-mean plots show that the significant ‘Year’ effect was caused mainly by significantly lower mean Taxa Richness in 2012 compared to that for other years.

Figure 5-3 Variation in Taxa Richness between sites and sampling occasions

* Note that site PCCK03 was not sampled from 2010 to 2012 and site PCCK06B was not sampled in 2010 or 2014.

Table 5-5 Results of Two-Way ANOVA comparing Taxa Richness between


Effect SS df MS F p

Intercept 6318.849 1 6318.849 472.0550 0.000

Treatment 3.457 1 3.457 0.2583 0.617

Year 706.132 4 176.533 13.1881 0.000

Treatment*Year 52.696 4 13.174 0.9842 0.439

Error 267.717 20 13.386

0

5

10

15

20

25

30

Taxa

rich

ness

2010

2011

2012

2013

2014


5.5.3 PET Richness

Figure 5-4 shows the variation in macroinvertebrate PET Richness between sites and sampling occasions. Of particular note is absence of any PET taxa at three sites (including the Control site PCCK01) in 2012, which is in keeping with the overall reduced Taxa Richness recorded at all sites that year. The maximum PET richness recorded in 2012 was 3. In most other years, maximum Taxa Richness has been 4 or 5. In 2014, it was actually 6, based on a sample collected from the Control site PCCK16. Surprisingly though, PET richness at the other Control site in 2014 was only 1, but it should be acknowledged that a low number of macroinvertebrates overall were recorded from that site in 2014.

Apart from 2012 and 2014, the maximum PET richness value recorded from Control sites did not exceed the maximum values recorded from Impact sites. Results of a Two-way ANOVA presented in Table 5-6 show that there was no significant difference in mean PET Richness between Control and Impact treatment group samples, but that there was a significant variation in mean PET Richness according to year. While not shown here, further investigation based on least-square-mean plots show that the significant ‘Year’ effect was caused mainly by significantly lower mean Taxa Richness in 2012 compared to that for 2013.

Figure 5-4 Variation in PET Richness between sites and sampling occasions


Table 5-6 Results of Two-Way ANOVA comparing PET Richness between


Effect SS df MS F p

Intercept 217.4626 1 217.4626 91.33887 0.000

Treatment 1.4186 1 1.4186 0.59583 0.449

Year 33.1036 4 8.2759 3.47606 0.026

Treatment*Year 2.2588 4 0.5647 0.23719 0.914

Error 47.6167 20 2.3808

0

1

2

3

4

5

6

7

PET

Rich

ness

2010

2011

2012

2013

2014


5.5.4 SIGNAL

Figure 5-5 shows the variation in macroinvertebrate SIGNAL between sites and sampling occasions. Of particular note is the fact that SIGNAL values are largely between 3 and 4, which based on the ranges given in Table 5-2 (after Chessman 1995) indicate that the status of the macroinvertebrate community in the study area is indicative of one affected by severe pollution. However, this is generally at odds with ratings based on AUSRIVAS O/E50 (refer Section 5.5.5). Moreover, ephemeral waterways such as those sampled are often colonised by generalist macroinvertebrate taxa with low to moderate sensitivity to changes in water quality (a finding that was highlighted in results presented for the PCPA by SKM (2012) which showed taxa with SIGNAL values ranging from 1 to 5 dominated the taxa present). Hence, the use of the Chessman (1995) categories as part of this assessment should potentially be reconsidered6.

Apart from 2014, the maximum SIGNAL score recorded from Control sites did not exceed the maximum values recorded from Impact sites. Results of a Two-way ANOVA presented in

Table 5-7 show that there was no significant difference in mean SIGNAL between Control and Impact treatment group samples or between sampling occasions.

Figure 5-5 Variation in SIGNAL between sites and sampling occasions

*Note that site PCCK03 was not sampled from 2010 to 2012 and site PCCK06B was not sampled in 2010 or 2014.

Table 5-7 Results of Two-Way ANOVA comparing SIGNAL between Treatments and Sampling Occasions (years)

Effect SS df MS F p

Intercept 336.1057 1 336.1057 1668.037 0.000

Treatment 0.0052 1 0.0052 0.026 0.874

Year 1.4585 4 0.3646 1.810 0.167

Treatment*Year 1.7342 4 0.4336 2.152 0.112

Error 4.0300 20 0.2015

6 It was only used here for the sake of consistency.

00.5

11.5

22.5

33.5

44.5

5

SIG

NAL

2010

2011

2012

2013

2014


5.5.5 AUSRIVAS O/E50 and Bands

Figure 5-6 shows the variation in macroinvertebrate AUSRIVAS O/E50 scores between sites and sampling occasions. AUSRIVAS bandings are also shown in this plot. Of particular note is the fact that O/E50 was zero at site PCCK02 in 2012 and 0.08 at sites PCCK01, PCCK06B and PCCK21 in 2012. This means that these sites lacked a substantial number of taxa that were predicted to occur there based on what would have been expected under natural reference conditions. This corresponds with the particularly low abundance and diversity of macroinvertebrate taxa recorded that year at all sites. In contrast, all sites recorded a band A rating based on their O/E50 scores in 2013. This corresponds with the much greater macroinvertebrate abundance and diversity recorded across all sites that year.

All sites recorded a band A rating at least once during the 2010 to 2014 period. Interestingly, though, the control site in Pine Creek (PCCK01) has only done so on one occasion, whereas the impact site in this creek system (PCCK02) has achieved this twice. O/E50 scores for PCCK01 have been lower than those for PCCK02 on three of the past five sampling occasions. This is possibly due to the lack of suitable habitat at the PCCK01.

In Copperfield Creek, the control site PCCK16 was rated band A on three occasions, Impact sites in this system all recorded a band A rating on two occasions. However, the only time O/E50 scores were higher for PCCK16 than for Impact sites sampled in Copperfield Creek was in 2010.

Overall, apart from 2010, the maximum O/E50 score recorded from Control sites did not exceed the maximum values recorded from Impact sites. Results of a Two-way ANOVA presented in Table 5-8 show that there was no significant difference in mean SIGNAL between Control and Impact treatment group samples or between sampling occasions.

Figure 5-6 Variation in AUSRIVAS O/E50 between sites and sampling occasions


0

0.2

0.4

0.6

0.8

1

1.2

1.4

PCCK01 PCCK02 PCCK03 PCCK06 PCCK06B PCCK16 PCCK21

AUSR

IVAS

O/E

50

2010 2011 2012 2013 2014

X

A

B

C

D


Table 5-8 Results of Two-Way ANOVA comparing AUSRIVAS O/E50 between Treatments and Sampling Occasions (years)

Effect SS df MS F p

Intercept 11.41907 1 11.41907 155.9799 0.000

Treatment 0.01087 1 0.01087 0.1485 0.704

Year 0.59971 4 0.14993 2.0479 0.126

Treatment*Year 0.33152 4 0.08288 1.1321 0.370

Error 1.46417 20 0.07321

5.5.6 Community Composition

Figure 5-7 and Figure 5-8 show the NMDS ordination plot results according to treatment and sampling occasion (year) respectively. Apart from four samples collected in 2012, sample scores largely fall into two main clusters at the 40 percent similarity level. The first of these clusters (middle right hand side of plot) contains mainly Control site samples, but also contains Impact site samples from 2013. The second cluster (lower middle of the plot) contains mainly Impact site samples and (at the same time) all samples collected in 2014 and the majority of samples collected in 2010 and 2011. These results indicate significant variation in macroinvertebrate community composition according to both treatment and sampling occasion, though in some years (e.g. 2013) differences between treatments were less obvious. This is confirmed by the results of PERMANOVA (Table 5-9), which show that there was a significant treatment and sampling occasion (year) effect, though there was no significant treatment by year interaction effect, so differences between treatments were still apparent in 2013. While not shown here, pairwise PERMANOVA tests showed that community composition varied between all years except for 2010 and 2011.

Sample scores for 2012 samples were scattered within ordination space compared to samples collected in other years. This indicates a greater degree of variability in community composition in 2012 compared to other years. This is not surprising given the low abundance and diversity of macroinvertebrates sampled that year.

SIMPER analysis showed that average dissimilarity between Control site samples and Impact site samples was 64.88 percent. Eight taxa contributed to just over 50 percent dissimilarity between these two treatment groups. These are shown in Table 5-10 and are comprised of taxa that have low to moderate sensitivity to pollution based on SIGNAL ratings given in Chessman (1995). The majority of these were more abundant in Control site samples than in Impact site samples. The taxon that contributed most to dissimilarity was Chironominae. This taxon has the greatest tolerance to pollution of those listed in Table 5-10, yet was slightly more abundant in Control site samples than in Impact site samples. The taxon that contributed the least to dissimilarity of those listed in Table 5-10 was Acarina. This taxon was the most pollution-sensitive taxon of those shown in this table and was slightly more abundant in Control site samples than in Impact site samples. Based on these results, there is no general trend of taxa with lower sensitivity to pollution being more abundant in Impact site samples than Control site samples (as would be expected under a scenario where there was an impact of mine affected water discharges on macroinvertebrates). Hence, while there was a significant effect of treatment on community composition recorded in this study, this does not necessarily indicate that releases of treated mine affected water were responsible.


Figure 5-7 NMDS plot showing variation in community composition between samples from Control and Impact Sites collected between 2010 and 2014

Figure 5-8 NMDS plot showing variation in community composition between sampled collected during the period 2010 to 2014


Table 5-9 Results of PERMANOVA analysis comparing community composition between treatment and sampling occasions (years). Values in red indicate significant differences

Source df SS MS Pseudo-F P(perm) Unique perms.

Treatment 1 3918.3 3918.3 2.9754 0.002 999

Year 4 25145 6286.2 4.7734 0.001 999

Treatment x Year 4 5550.1 1387.5 1.0536 0.382 999

Residual 20 26338 1316.9

Total 29 65798

Table 5-10 Taxa that contributed most to dissimilarity in macroinvertebrate

community composition between Control and Impact Sites based on SIMPER Analysis

Taxa SIGNAL rating

Control Av.

Abund.

Impact Av.

Abund.

Impact Av.

Diss.

Diss/SD Contrib% Cum.%

Chironominae 3 12.49 11.01 8.84 1.62 13.63 13.63

Tanypodinae 4 7.5 6.34 5.2 1.18 8.01 21.64

Palaemonidae 4 4.18 1.22 4.06 0.86 6.26 27.9

Ceratopogonidae 4 5 5.73 3.73 1.37 5.75 33.65

Caenidae 4 4.4 1.93 3.36 1.14 5.17 38.82

Baetidae 5 3.93 2.52 3.07 1.23 4.73 43.55

Orthocladiinae 4 3.46 2.12 2.63 1.16 4.05 47.59

Acarina 6 2.81 2.65 2.57 0.91 3.96 51.55

5.6 Conclusions

Results of this study show that there were no significant differences in any of the univariate macroinvertebrate indices between Control site and Impact site sample groups. There was, however, significant year to year variation in Abundance, Taxa Richness and PET Richness. The latter related mainly to the very low diversity and abundance of macroinvertebrate fauna collected in 2012 and the high abundance and diversity of macroinvertebrate fauna collected in 2013.

Results of multivariate analysis showed that there was a significant difference in community composition between Control site and Impact site samples as well as between years. A difference in community composition between treatment groups was attributable largely to differences in relative abundance of taxa with low to moderate pollution sensitivity. Further, there was no consistent pattern of higher abundances of these taxa in Impact site samples, as one might expect under a pollution impact scenario. Hence, those differences probably relate to factors other than treated mine affected water release.


Overall there is no evidence to suggest that the PCPA has had any negative impact on the macroinvertebrate community in Pine Creek and Copperfield Creek. This result might be at least partly attributable to the low to moderate levels of pollution sensitivity associated with the macroinvertebrate taxa present within the PCPA study area.

It should be pointed out that the data analyses performed on the PCPA data have limited statistical power due to the fact that there has not been any within-site sampling replication. Hence there is a real risk of both Type I errors (rejecting the null hypothesis when it is true) and Type II errors (accepting the null hypothesis when it is false). Hence, these results should be interpreted with caution. Given the level of between year and within-treatment variability observed in this study, this issue should be addressed through changes to the study design in future programs.

5.7 Recommendations

The key issue to be addressed for future monitoring rounds is the study design. Currently, only one AUSRIVAS edge habitat sample is collected at each site on each sampling occasion. While this approach adheres to the NT AUSRIVAS methodology described in Lamche (2007), it does not provide for adequate within-site replication and statistical power. Hence, there is a chance that data analyses results based on this study design could indicate a treatment effect when there was none (to the detriment of CGAO) or no treatment effect when there was one (to the detriment of the environment). Based on our experience, the level of sampling replication should be set initially at two samples per site until sufficient data are available to perform a valid power analysis7 and, from this, the adequate level of replication determined.

SKM (2012) suggested that the use of abundance as a metric should be reconsidered due to the potential for sub-sampling bias skewing the results. Such impacts may have skewed the 2013 abundance results, which were an order of magnitude or so higher than those recorded in other years. In that year, the proportion of the sample processed ranged between 6 and 30 percent, whereas in other years it was much higher than this. Their argument was for 100 percent of the sample to be processed in all cases in order to provide true quantitative data and to eliminate such bias. However, in the case of the 2013 samples, this would have taken a long time (i.e. if processing 6 percent of the sample took 4 hours, then processing 100% of the sample would take up to 68 hours). It is therefore recommended that samples be processed in the same way as they have done to date, but trends for abundance be assessed qualitatively only (i.e. not analysed statistically, but basic trends described).

Lamche (2007) recommended against the use of SIGNAL for macroinvertebrate monitoring and results of this study and that by SKM (2012) highlight why this may be valid. The vast majority of taxa collected in the PCPA study area have SIGNAL scores in the low to mid-range. This is expected for ephemeral streams in the Northern Territory as the taxa present need to adapt to rapidly changing water quantity and quality in these systems and, therefore, need to have physiological tolerances or behavioural traits that make them less vulnerable to such changes. To that extent, it is perhaps not unsurprising that there was no significant treatment effect or between year effect recorded in relation to SIGNAL, or, that differences in community composition between treatments was not easily explainable based on SIGNAL ratings for individual taxa. Certainly, SIGNAL data should not be assessed against ranges given by Chessman (2012) relative to different level of disturbance based on the fact that SIGNAL levels will be naturally low for ephemeral streams in the Northern Territory. However, it could still be a useful metric for comparing between treatments given improvements in the level of sampling replication, so it should be retained for now and its use reviewed after the next two sampling rounds.

7 Most likely after the next two sampling rounds.


6. Ecotoxicology 6.1 Introduction

WDL 166-02 requires the Pine Creek Project Area discharge to be assessed using site specific direct toxicity assessment (DTA) using methodology as set out in Section 8.3.6 (ANZECC 2000). DTA assesses the combined effects of a number of compounds of unknown identity and concentration in complex mixtures such as mine discharges. DTA provides an integrated measure of the additive/synergistic/ameliorative toxicity of chemicals within a mixture accounting for interactions between compounds. DTA provides a direct measure of toxicity and bioavailability and is a reliable qualitative indicator of biological community impacts (ANZECC 2000).

Site specific toxicity tests representative of the receiving environment were conducted. Test species were indigenous to, or representative of, the receiving ecosystem. Water samples collected from Copperfield Dam during the wet season were used as the diluent to best represent the receiving environment.

6.2 Ecotoxicology Program

6.2.1 Ecotox Sampling Locations

CGAO has developed an Ecotoxicological Monitoring Program for the Pine Creek Project Area for 2013. This program assesses toxicity of waters from the sites listed in Table 6-1. The program uses a combination of DTA with a suite of ecologically relevant bioassays for the Authorised Discharge Points and a series of screening tests where only 100 percent of receiving water is assessed and compared against a control. DTA is the preferred methodology for assessing environmental impacts of complex effluents such as mine water.

Sampling occurred during discharge events following the CGAO Ecotoxicological Monitoring Plan.

Table 6-1 Ecotox Monitoring Locations

Site Code Description Assessment

Pine Creek

PCCK04 WDL 166-02 Authorised discharge point within Pine Creek at tenement boundary MLN13.

Serial dilution

PCCK01 Pine Creek upstream of Green Valley Road (control). Screening test

PCCK03 One kilometre further downstream from PCCK02 at Railway line culvert, Pine Creek.

Screening test

Copperfield Creek

CDW Copperfield Dam Water. Diluent water

PCPWD Pine Creek Process Water Dam, WDL 166-02 Authorised discharge point.

Serial dilution

PCCK16 Copperfield Creek upstream of any mine site discharge at the Jindare/Umbrawarra Road Crossing (control).

Screening test

PCCK06 100 metres downstream of the confluence of Copperfield Creek with the process water dam spillway tributary (compliance).

Screening test

PCCK06B Two kilometres further downstream of PCCK06. Screening test

PCCK21 Copperfield Creek- 20km downstream of discharge at location known as 'Blue Hole".

Screening test


6.2.2 Bioassays

The CGAO 2013 Ecotoxicological Monitoring Program uses a suite of ecologically relevant species for assessment of potential toxicity to a tropical freshwater ecosystem. Where available the bioassays are chronic tests which determine sub-lethal impacts such as growth and reproduction and is the ANZECC (2000) preferred method for assessing environmental impacts. The use of chronic bioassays also avoids the use of application factors to convert acute data to chronic data for calculation of the species sensitivity distribution (SSD). The program meets the ANZECC (2000) requirements for the use of three to five species from four taxonomic groups for the calculation of a SSD which can be used to determine safe dilution factors of the mine water. Table 6-2 lists the bioassays used in the 2013 ecotoxicology program.

Table 6-2 Ecotox Bioassays

Species Type Bioassay

Hydra (Hydra viridissma) Chronic 96 hour population growth

Cladoceran (Ceriodaphnia dubia) Chronic 7 day reproduction

Duckweed (Lemna aquinoctialis) Chronic 96 hour population growth

Green microalga (Chlorella vulgaris) Chronic 72 hour growth inhibition

Eastern Rainbowfish (Metanotaenia splendida) Chronic 96 hour larval imbalance

6.2.3 Dilution Water

Water sampled from Copperfield Dam was used as the dilution water in the serial dilution bioassays for PCCK04 and PCPWD. However, it must be noted that the use of natural water as the dilution water can introduce problems related to background toxicity from compounds further upstream. To overcome this issue, controls using laboratory diluents were also utilised.

6.2.4 Species Sensitivity Distribution

The results from the 2013 ecotoxicology monitoring program for sites PCCK04 and PCPWD were placed in the BurrliOZ (Campbell et al., 2000) statistical analytical program. This program uses the EC108 values from each bioassay to calculate the SSD for the 80 percent species protection level. The dilution factors were then calculated from the 80 percent species protection level value for each discharge point. This dilution factor will protect 80 percent of the species in the receiving ecosystem from a 10 percent reduction in growth or reproduction. The dilution factor can be used to assist in deriving site specific concentrations of contaminants that will not adversely impact on organisms within the receiving ecosystem. Concentrations of individual chemicals cannot be extrapolated from DTAs for use as trigger values. However, concentrations can be used for monitoring purposes to ensure that the dilution factors are met at the appropriate monitoring site.

8 Effect Concentration where 10% of the population exhibits a response after a specified exposure duration.


6.2.5 Chemistry

Chemistry analysis was conducted on all the samples for the analytes listed in Table 6-3.

Table 6-3 Chemistry Analysis

Parameters Analytes

Field pH, electrical conductivity, dissolved oxygen and temperature

Metals (total and filtered) Aluminium, arsenic, cadmium, cobalt, copper, iron, manganese, nickel, lead and zinc

Cations and anions Calcium, potassium, sodium, magnesium, sulphate, alkalinity, titratable acidity, hardness (CaCO3)and total suspended solids

Others Total organic carbon, dissolved organic carbon, total phosphorous, total nitrogen, NO3, NO2, NH3 and PO4

6.3 Ecotoxicology Results

The bioassays in the 2013 sampling program were conducted by a NATA accredited laboratory.

Sites shown above were sampled on the 6 April 2013 and sent directly to the laboratory where testing commenced within three weeks of receipt, with the exception of the rainbowfish larvae bioassay which commenced in October 2013. An assumption has been made that the sample was stored correctly and the chemistry remained unchanged during the storage time.

The species used were appropriate for the site and the EC10 and LC50 results for PCPWD were of sufficient quality to be used in the BurrliOZ (Campbell et al. 2000) program for species sensitivity distribution (SSD) calculations. The cladoceran (Moinodaphnia macleayi) has been replaced with the temperate cladoceran Ceriodaphnia dubia in this suite of bioassays.

Screening results are considered to show a toxicity if the results are <80 percent of the controls. This is based on the quality control parameter used by the testing laboratory.

Summaries of the Ecotox Report by Ecotox Services, “Toxicity Assessment of waters from Copperfield Creek, November 2013” results are provided in Table 6-4 and Table 6-5. Summaries of the Ecotox Report by Ecotox Services, “Toxicity Assessment of waters from Pine Creek, November 2013”, results are provided in Table 6-6 and Table 6-7.

The results of the site specific DTA testing performed by Ecotox Services used in this assessment do meet the laboratory NATA requirements for quality assurance/quality control (QA/QC) parameters. The diluent water from Copperfield Dam met all quality criteria for use as a diluent.


Table 6-4 Summary of PCPWD ecotox results

Test EC/IC10 (95% confidence limits)

% PCPWD

EC/IC50 (95% confidence limits)

% PCPWD

Microalgal 72-hour growth inhibition <6.3 7.1**

Duckweed 96-hour growth 0.9 (0.6 – 0.9) 1.2 (1.1 – 1.3)

Cladoceran 6-day reproduction 0.4 ** 0.6 (0.4 – 0.8)

Hydra 96-hour growth 16.5 (12.1 – 20.0) 50.5 (41.1 - 63.0)

Fish 96 hour larval imbalance 0.3 (0.2-0.5) 1.1 (0.8-1.5)

** 95% confidence limits not provided

Table 6-5 Summary of Copperfield Creek Screening Ecotox Results

Test Control PCCK06B PCCK06 PCCK16 PCCK21

Microalgal 72-hour % growth 100 51 41 88 80

Duckweed 96-hour % growth 100 0 0 100 104

Cladoceran 6-day % reproduction 100 0 0 0 113

Hydra 96-hour growth % growth 100 86 81 95 90

Fish 96 hour larval imbalance % unaffected

100 0 5 95 100

Table 6-6 Summary of PCCK04 Ecotox Results

Test EC/IC10 (95% confidence limits)

% PCPWD

EC/IC50 (95% confidence limits)

% PCPWD

Microalgal 72-hour growth inhibition 18.6 (16.8 – 20.1) 90.4**

Duckweed 96-hour growth 8.7 (6.3 – 16.8) 16.5 (7.4 – 20.1)

Cladoceran 6-day reproduction 1.3 (1.0 – 2.1) 6.2 (2.9 – 7.7)

Hydra 96-hour growth 98.0 >100

Fish 96 hour larval imbalance 10.7** 22.4 (14.9 – 29.2)

** 95% confidence limits not provided


Table 6-7 Summary of Pine Creek Screening Ecotox Results

Test Control PCCK01 PCCK03

Microalgal 72-hour % growth 100 97 76

Duckweed 96-hour % growth 100 92 46

Cladoceran 6-day % reproduction 100 122 0

Hydra 96-hour % growth 100 100 93

Fish 96 hour larval % imbalance 100 100 15

6.3.1 Toxic Units

Toxic units were calculated for analytes identified as contributing to toxicity. Toxic units were calculated by dividing the concentration of the analyte by the 80 percent trigger value or SSTV. The larger the TU the greater contribution to toxicity.

6.3.2 Screening Results

Copperfield Creek

The screening results for Copperfield Creek show that site PCCK21 is not significantly different from the controls. This is supported by the chemistry data which show that all analytes with the exception of zinc are similar at both sites. Zinc is present at PCCK21 at 50 µg/L which is above the SSTV of 31 µg/L (Table 6-12) but unlikely to contribute to toxicity at this level. The hydra was the least sensitive species with all sites showing a similar response.

The cladoceran result at PCCK16 is anomalous when compared to the other bioassays as all the replicates died in the test. It is not possible to determine the cause of the observed toxicity as all analytes are below the concentrations that have potential to cause acute toxicity. The naturally occurring elevated aluminium at the site of 190 µg/L does not have the potential to cause acute toxicity as the 7 day NOEC concentrations for crustaceans range from 136 µg/L to 1,720 µg/L (ANZECC 2000).

Similar toxicities were observed at PCCK06B and PCCK06 for all bioassays. The observed toxicity could possibly be attributed to zinc as both sites show zinc levels well above the SSTV at 430 µg/L (13.9 TU) and 570 µg/L (18.4 TU) respectively. These results show that both sites are within the mixing zone for the PCPWD discharge

Pine Creek

The screening results for Pine Creek show that site PCCK01 toxicity is not significantly different from the controls for all bioassays. However, Site PCCK03 does show significant differences in the cladoceran, duckweed and fish bioassays. The concentration of aluminium is elevated at PCCK03 however, as mentioned above the concentration is insufficient to cause toxicity to the cladoceran. Zinc is elevated at the site, therefore the observed toxicity could be attributed to the zinc concentration of 200 µg/L (6.5 TU).


6.3.3 Species Sensitivity Distribution

Copperfield Creek

PCPWD showed toxicity to all the species used in the bioassays and is more toxic than PCCK04. This is possibly due to the elevated zinc (255 TU) and nickel (7 TU) in the sample. Sulfate is also elevated with a concentration of 330 mg/L, however, this is lower than the hardness modified trigger value of 675 mg/L derived by Elphick et al. (2011). The pH of the sample is low, however, as the concentrations tested were highly diluted with Copperfield Dam water, the pH was similar to background in all test samples.

Pine Creek

PCCK04 showed no toxicity to the hydra, whereas, the cladoceran reproduction was the most sensitive species to the sample. From the chemistry results (Table 6-12), zinc is elevated at the site, therefore the observed toxicity could be attributed to the zinc concentration of 540 µg/L (17 TU) The EC10 results were placed in the BurrliOZ (Campbell 2000) SSD program and the results are shown in Table 6-8.

Dilution Factor

The EC10 values in Table 6-4 and Table 6-6 were placed in the BurrliOZ (Campbell et al. 2000) SSD program. The results are shown in Table 6-8.

Table 6-8 Species Sensitivity distribution results

% Species Protection

PCCK04 % Dilution PCPWD % Dilution

80 3.94 1:25 0.42 1:238

90 2.03 1:49 0.28 1:357

95 1.10 1:91 0.21 1:476

99 0.28 1:357 0.13 1:769

The SSD table of results shows that the PCCK04 sample is required to meet a dilution factor of 1:25 to provide an 80 percent species protection level. This is less than the dilution required for PCPWD of 1:238 due to the differences in water quality, most probably related to the zinc concentrations.


6.3.1 Chemistry Results

Table 6-9 Chemistry Results Dissolved Metals (9 April 2013, Envirolab Services CoA 88633)

Analyte SSTV PCCK01 PCCK03 PCCK04 PCCK06 PCCK06B PCCK16 PCCK21 PCPWD Copperfield Dam

pH 6.0-7.5 6.6 6.6 6.4 6.7 6.7 6.8 69. 5.0 7.5

EC µS/cm 20-250 28 87 140 120 99 52 57 820 42

DO mg/L - 8.4 9.1 9 9 9.2 9.2 8.8 9.1 8.8

Acidity as CaCO3 mg/L - <5 <5 <5 <5 <5 <5 <5 43 <5

TSS mg/L - 14 7 13 10 16 12 20 <5 8

TOC mg/L - 6 5 5 3 4 5 3 3 3

DOC mg/L - 5 4 4 3 3 4 2 2 3

TP mg/L - <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

TN mg/L - 0.5 0.5 0.4 0.3 0.6 0.3 0.4 0.7 0.7

Calcium mg/L - <0.5 2.9 4.5 3.0 2.4 0.6 1.5 26 1.4

Potassium mg/L - 1.7 2.1 2.2 2.1 1.9 1.9 1.8 4.6 1.5

Sodium mg/L - 3.6 4.2 4.6 8.2 6.9 4.1 5.7 49 3.2

Magnesium mg/L - 0.6 5.1 9.0 7.0 5.6 1.0 2.6 70 1.4

Bicarbonate alkalinity mg/L - 23 20 14 28 25 25 28 <5 35

Sulfate mg/L - <1 21 43 33 26 <1 9 330 <1

Chloride mg/L - 2 2 2 2 2 1 1 9 1

Hardness mg/L - 3 28 48 36 29 6.0 14 350 10


Analyte SSTV PCCK01 PCCK03 PCCK04 PCCK06 PCCK06B PCCK16 PCCK21 PCPWD Copperfield Dam

Dissolved metals

Aluminium µg/L 508 300 680 41 36 34 190 70 690 37

Arsenic µg/L 140 2 4 2 1 <1 <1 <1 7 <1

Cadmium µg/L 0.8 <0.1 0.4 1.1 0.7 0.5 <0.1 <0.1 8.4 <0.1

Cobalt µg/L - <1.0 7 12 13 9 <1 <1 180 <1

Copper µg/L 5 <1 4 5 2 2 <1 <1 21 <1

Iron µg/L - 370 470 47 120 140 320 140 57 140

Manganese µg/L 3,600 17 210 370 470 350 9 29 6,200 8

Nickel µg/L 17 <1 16 12 9 7 <1 1 120 <1

Lead µg/L 9.4 <1 <1 <1 <1 <1 <1 <1 6 <1

Zinc µg/L 31 6 200 540 570 430 4 50 7,900 11

Highlighted cells exceed SSTVs


6.4 Historical Ecotox Data

6.4.1 Results

Ecotox data from all the sampling programs has been compiled and is shown in Table 6-9 and Table 6-10. No samples for the Copperfield Creek sites were tested in 2012 or 2010. The 2011 tests included the midge and shrimp acute bioassays, these were changed to the more sensitive chronic bioassays for the 2013 sampling.

Table 6-10 Historical Screening Toxicity Data

Site Year Algae Duckweed Cladoceran Hydra Fish Shrimp Midge

% of controls

PCCK06B 2013 51 0 0 86 0 NT NT

2011 NT 150 33.9 NT 75 100 100

PCCK06 2013 41 0 0 81 5 NT NT

2011 NT 114 38.1 NT 80 100 95

PCCK16 2013 88 100 0 95 95 NT NT

2011 NT 150 100 NT 90 100 95

PCCK21 2013 80 104 113 90 100 NT NT

2011 NT 185 49.9 NT 100 100 100

PCCK01 2013 97 92 122 100 100 NT NT

2012 28.6 103 100 108 77 NT NT

PCCK03 2013 76 46 0 93 15 NT NT

PCCK02 2012 1.2 0 0 0 0 NT NT

Table 6-11 Historical PCPWD Toxicity Data (ERISS 2010)

Year Algae EC10

Duckweed EC10

Cladoceran EC10

Hydra EC10

Fish EC10

Dilution 80% SP

2013 <6.3 0.9 0.4 16.5 0.3 1:238

2009 2.5 0.5 0.16 0.1 4.6 1:1,000


6.4.2 Discussion

Copperfield Creek

The historical results (Table 6-9) show that the toxicity of the PCCK06 and PCCK06B sites varies between the sampling periods. This is probably due to the flow in the creek in relation to the flow from PCPWD as evidenced by the zinc concentrations in 2011 which were 39-66 µg/L at PCCK06 and 85-108 µg/L at PCCK06B (SKM 2012). This contrasts to the concentrations detected in 2013 of 570 µg/L at PCCK06 and 430 µg/L at PCCK06B and this will also account for the increase in toxicity observed in the 2013 sample.

Table 6-12 PCPWD Chemistry Data

Year Aluminium µg/L

Cadmium µg/L

Cobalt µg/L

Copper µg/L

Nickel µg/L

Lead µg/L

Zinc µg/L

2009 14,300 76 1,280 192 839 49 61,700

2013 690 8.4 180 21 120 6 7,900

% reduction 95 89 86 89 86 88 88

In contrast to the downstream toxicity data (which is influenced by flow rates) the PCPWD toxicity has decreased since the 2009 testing (Table 6-10) (ERISS 2010). This is due to the reduction in metals in the PCPWD sample as shown in Table 6-11 with an average reduction in metals of 88.5 percent over four years. The water quality results for PCPWD since January 2010 show that there has been a reduction in metal concentrations with a downward trend in metal concentrations evident as indicated by Figure 6-1, however, not to the extent shown in the Ecotox samples. The metal concentrations in the 2009 sample are above the maximum concentrations detected at the site since January 2010, therefore the 2009 sample provides a worst case scenario for potential toxic effects as it was sampled at the end of the dry season. The 2013 sample provides an indication of the best water quality at site with concentrations below the median values since January 2010 as it was sampled at the end of the wet season. Neither sample provides an accurate representation of zinc median water quality in PCPWD which is calculated at 22,000 µg/L from data including January 2012 to June 2014.

Figure 6-1 PCPWD zinc concentrations


Pine Creek

The Pine Creek results were derived from samples at different locations between the years. However, the results show that both sites are within the mixing zone with PCCK03 showing less toxicity as it is further downstream than PCCK02 (Table 6-9).

There is no historical data to compare the ecotoxicology of PCCK04, however, the water quality shows that the sample tested in April 2013 was representative of the median water quality sampled at PCCK04 since December 2012. Therefore, the sample tested does provide a good indication of potential impacts on the downstream ecosystem in Copperfield Creek.

6.5 Conclusions

The screening tests showed that the results are influenced by the water flows in the creeks and it is difficult to compare the results from the same sites from different years due to this influence. However, screening tests are useful for determining the edge of a mixing zone, however, this is also dependent on discharge volume and creek flow and can be measured more easily by water chemistry.

Zinc is present in concentrations that have the potential to cause toxicity in PCCK03, PCCK06 and PCCK06B. Zinc can be measured and the results used to determine the influence of the discharges from PCCK04 and the PCPWD on the receiving water in place of using screening bioassays.

Both the PCCK04 and PCPWD water samples show that dilution is required to ameliorate toxicity, particularly for the cladoceran, the most sensitive species. Zinc is the main contaminant of concern in both samples, however, PCPWD also contains nickel, copper, manganese and cadmium in concentrations that have the potential to cause toxicity. It is unlikely that aluminium has the potential to have a major contribution to toxicity as discussed previously.

The PCPWD dilution factor calculated by ERISS (2010) of 1:1,000 shows the dilution required for a worst case water quality scenario. The 2013 PCPWD dilution factor of 1:238 shows the dilution for the best case water quality scenario.

The current management of PCPWD discharge does not allow the active utilisation of the SSD calculated for downstream environmental protection. To obtain the maximum value of the SSD results and to manage discharge from PCPWD in a more environmentally relevant manner a method that allows greater control and the ability to measure the discharge is required. The same comment applies to PCCK04, without a responsive management control of discharge volumes the results of the toxicity tests are not able to be utilised to their greatest potential.

6.6 Recommendations

Based on the conclusions above the following changes are recommended to the ecotoxicology monitoring program:

6.1. Remove all screening bioassays from the program.

6.2. Conduct the direct toxicity assessment on PCCK04 and PCPWD on a three yearly basis. As water quality monitoring is taken on a routine basis, the water quality results will provide information on the potential toxicity of the discharge water which can be confirmed with the three yearly ecotox program.



6.5 Investigate using water quality data and ecotoxicology results to date to determine a process where ecotoxicity can be predicted based on water quality results.


7. Environmental Risk Assessment 7.1 Introduction

Crocodile Gold maintains the Pine Creek Project Area (PCPA). The site received a Waste Discharge Licence (WDL 166-02) on 17 December 2012 due to expire 31 August 2014 WDL. WDL 166-02 outlines the requirements associated with discharge at the PCPA. This risk assessment investigates the potential impacts of the licenced discharge to the receiving waterways, Pine Creek and Copperfield Creek and their associated values and beneficial uses.

7.1.1 Potential Risks to Aquatic Biota from Mine Discharges

Discharges from mining operations can release a mix of metals and ore-extracting substances as well as acidic water to the receiving river which may negatively impact the aquatic beneficial uses and values of the waterway (Dallas and Day 2004).

Pine Creek and Copperfield Creek support a diverse aquatic community including algae, macroinvertebrates, fish, amphibians and reptiles, including the Environment Protection and Biodiversity Conservation Act (1999) listed freshwater crocodile.

Without mitigation, acidic, metal-rich waters have the potential to place stress on macroinvertebrate communities (Gray 1998) as well as higher trophic levels such as fish, amphibians and reptiles. Common stressors in waters receiving mine water discharges stem from increased acidity (lowered pH), heavy metals and the precipitation of the iron (III). The overall effect of these stressors on macroinvertebrate communities are typically defined by a reduction in species diversity and associated shifts from sensitive to stressor- tolerant taxa. This loss of species diversity has the potential to lead to larger populations of the unaffected organisms through a reduction of predation and competition (Mason 2002).

Increased acidity influences macroinvertebrates through disruption of ionic balance across the organism’s membranes (Jarvis and Younger 1997).

Organisms such as snails with calcium carbonate shells are likely to have their shell dissolved in acidic waters (Kelly 1988). Since all carbonates are dissociated at pH 4.2 (Ravengai et al. 2005) the presence of shelled organisms is unlikely below this pH level. Gerhardt et al. (2002) estimated that these organisms can withstand a minimum pH of 5-5.5.

The increased acidity of mine waters increases the bioavailability of metals (Cherry et al. 2001). This may lead to the accumulation of metals in organisms. Grazers feeding on biofilms in a metal-impacted stream were recorded as having zinc concentrations of two to four times those in organisms feeding in a non-impacted stream (Courtney and Clements 2002). Mason (2002) suggested copper has the greatest effect on the macro-invertebrates, followed by aluminium.

The loss of algae and other primary producers will reduce the food available to herbivorous macro-invertebrate species (Courtney and Clements 2002). Mine affected waters have the potential to lower rates of decomposition which in turn lowers nutrient availability and the growth of algae (Mason 2002).

Alterations of the food web may modify competition and predation dynamics (Clements 1999); this may include the loss of predators, particularly fish (Nelson and Roline 1996), potentially increasing populations of the prey species.


7.1.2 2012 Risk Assessment Approach

In 2012, a qualitative environmental risk assessment was conducted investigating the potential PCPA impacts from discharge to Pine Creek and Copperfield Creek and their associated values and beneficial uses (SKM 2012). The approach taken in SKM (2012) identified risk activities associated with the PCPA discharges and qualitatively assessed the potential environmental impacts associated with these activities. These risk activities, as taken from “Table 8.5 in Pine Creek Project Area 2010-2012 Environmental Monitoring Report” SKM (2012) and identified risk impact were:

Discharge during the dry season – Copperfield Creek and Pine Creek (High risk)

Discharges of untreated water during high flow events (Low risk)

Uncontrolled discharges with seepage – Copperfield Creek (Low risk)

Uncontrolled discharges associated with seepage – Pine Creek (High risk)

Contaminated water enters the groundwater table (Medium risk)

Bioaccumulations in aquatic organism and subsequent health risk (Low risk)

Toxicity to aquatic organisms (Severe risk)

Lack of data to inform management practices (Severe risk)

7.1.3 2014 Risk Assessment Approach

Based on the availability on monitoring data for the PCPA, in 2014 a semi-quantitative approach will be used to conduct the risk assessment in this report. This approach will allow for more targeted and defendable outcomes to derive appropriate management actions.

7.2 Methodology

To assess the risk posed by discharges from the PCPA to Pine Creek and Copperfield Creek and to the beneficial use “Protection of aquatic ecosystems” as defined under the Water Act (1992), an Environmental Risk Assessment (ERA) was undertaken. Specifically, the focus of this ERA is on the aquatic environment of Pine Creek and Copperfield Creek in the vicinity of surface water monitoring sites listed in WDL-166-02.

The overall approach adopted for this assessment is consistent with AS/NZS ISO 31000:2009 (which supersedes AS/NZ 4360:2004). The objective of this assessment is to identify risks to aquatic values arising from the mine discharge. The method used for the risk assessment is based on the Aquatic Value Identification and Risk Assessment (AVIRA) process (Peters et al. 2009) and is compliant with the AS/NZS ISO 31000:2009 risk assessment framework. The AVIRA-based method identifies the association of threats to assets, values or beneficial uses and recognises that not all stressors have an equal impact.

The risk assessment was conducted in three phases:

Phase 1 – Problem Formulation – Establishing the context, review of beneficial uses, threats and risk identification and development of the risk analysis method.

Phase 2 – Risk analysis – conduct the risk analysis.

Phase 3 – Risk Characterisation.

This method provides a detailed approach to assess risk within a spatially based framework. The method identifies the association of threats to values and recognises that not all threats have an equal impact on all values. The association rating is used to inform the overall assessment of risk


7.3 Problem Formulation

The problem formulation stage is the crucial first step in the process that defines the overall scope and boundaries of the risk assessment. The problem formulation stage for the risk assessment includes:

Identifying the environmental management of discharges from the PCPA.

Identification of the spatial boundaries.

An overview of the existing background information on environmental values, threats and known impacts posed by the discharge of mine water.

Development of a detailed risk register.

7.3.1 Spatial Boundaries of the Environmental Risk Assessment

The spatial boundary utilised for this ERA is the aquatic environment of Pine Creek and Copperfield Creek in the vicinity of surface water monitoring sites listed in WDL-166-02.

7.3.2 Background Condition (2010-2014)

Pine Creek – Upstream

Summary of water quality data measured from the upstream location on Pine Creek, PCCK01 is presented in Table 7-1. The 80th percentile data is compared against the ISSTV consistent with the risk assessment methodology to provide the worst case scenario of upstream conditions. Water quality upstream is generally within the 2013/14 ISSTVs. However, turbidity was greater than upper limit of the ISSTV of 15 NTU at 38 NTU, and iron concentration was higher than the ANZECC (2000) low reliability trigger value of 300 µg/L at both the 20th percentile and 80th percentile, as well as the median value. In addition, turbidity and iron were the only parameters in which the median values were greater than the ISSTVs. This indicates that water quality upstream of the discharge point on Pine Creek is generally within acceptable limits but that the aquatic ecosystem may experience impacts associated with high iron concentrations and elevated turbidity.

Copperfield Creek – Upstream

Summary of water quality data measured from the upstream location on Copperfield Creek, PCCK16 is presented in Table 7-2. The 80th percentile data is compared against the ISSTV consistent with the risk assessment methodology to provide the worst case scenario of upstream conditions. Water quality upstream is generally within the 2013 ISSTVs. However, iron concentration was higher than the ANZECC (2000) low reliability trigger value of 300 µg/L at both the 20th percentile and 80th percentile. Iron was also the only parameter in which the median value was above the ISSTV. This indicates that water quality upstream of the discharge point on Copperfield Creek is generally within acceptable limits but that the aquatic ecosystem may experience impacts associated with elevated iron.


Table 7-1 PCCK01 Pine Creek (upstream) Summary Data (2010 to 2014) and ISSTVs

PCCK01 ISSTV Min Median Max 20th %ile 80th %ile

pH 6.0-7.5 5.3 6.6 8.3 6.2 6.9

EC µS/cm 20-250 19 40 213 33 58

DO % 35-120 17 80 162 57 109

TDS mg/L NA 14 26 77 22 41

Al µg/L 508 15 96 2600 28 362

As µg/L 140 0.50 1.00 7.0 0.50 2.0

Cd µg/L 0.8 0.01 0.05 0.60 0.05 0.05

Co µg/L 2.8* 0.09 0.50 2.0 0.50 0.50

Cr µg/L 40 0.30 0.50 2.0 0.50 0.50

Cu µg/L 5 0.50 0.50 11.00 0.50 2.4

Fe µg/L 300* 90 470 2500 300 774

Pb µg/L 9.4 0.50 0.50 4.00 0.50 0.50

Mn µg/L 3600 0.50 16 120. 7.0 24

Ni µg/L 17 0.26 0.50 0.50 0.50 0.50

Se µg/L 34 0.10 0.50 2.0 0.50 0.50

Zn µg/L 31 0.5 2.0 170 0.50 10

Ca mg/L NA 0.25 0.50 2.80 0.25 0.80

K mg/L NA 0.90 1.70 3.60 1.10 2.3

Na mg/L NA 0.25 3.70 6.80 2.60 4.6

Mg mg/L NA 0.25 0.70 1.60 0.50 1.0

HCO3 mg/L NA 7 15 32 11 20

CO3 mg/L NA 0.1 0.5 2.5 0.5 2.5

Alk. mg/L NA 7 15 32 11 20

SO4 mg/L NA 0.3 0.5 6.0 0.5 0.5

Cl mg/L 13 0.5 3.0 7.0 2.0 4.0

Hardness. mgCaCO3/L

NA 1.5 4.0 10.0 3.0 6.0

TSS mg/L NA 3 3 51 3 9

Turb. NTU 2-15 6 20 63 9 38

* Denotes no ISSTV and ANZECC (2000) low reliability trigger value used NA denotes no ISSTV or ANZECC (2000) trigger value Dark grey shading denotes exceedance of ISSTV


Table 7-2 PCCK16 Copperfield Creek (upstream) Data Summary (2010 to 2014) and ISSTVs

PCCK16 ISSTV Min Median Max 20th Percentile

80th Percentile

pH 6.0-7.5 5.1 6.6 7.8 6.3 6.9

EC µS/cm 20-250 6.48 43 487 34 54

DO % 45-120 6.50 85 155 57 113

TDS mg/L NA 12 29 2665 22 35

Al µg/L 590 5.0 43 1300 10 250

As µg/L 140 0.25 0.50 5.0 0.50 1.0

Cd µg/L 0.8 0.01 0.05 1.20 0.05 0.05

Co µg/L 2.8* 0.05 0.50 3.00 0.50 0.50

Cr µg/L 40 0.20 0.50 1.0 0.50 0.50

Cu µg/L 2.5 0.50 0.50 11 0.50 0.50

Fe µg/L 300* 40 510 2000 340 750

Pb µg/L 9.4 0.14 0.50 3.00 0.50 0.50

Mn µg/L 3600 0.14 11 78 6.00 20

Ni µg/L 17 0.14 0.50 8.00 0.50 0.50

Se µg/L 34 0.10 0.50 1.00 0.50 0.50

Zn µg/L 95 0.50 4.00 160 0.50 16

Ca mg/L NA 0.25 0.80 4.20 0.60 1.0

K mg/L NA 1.00 1.70 3.70 1.40 2.2

Na mg/L NA 0.70 4.50 17 3.6 5.5

Mg mg/L NA 0.60 1.20 5.40 0.90 1.5

HCO3 mg/L NA 0.05 18 62 13 24

CO3 mg/L NA 0.05 2.5 14.0 0.23 2.5

Alk. mg/L NA 0.05 18. 62 13 24

SO4 mg/L NA 0.10 0.50 35 0.50 0.50

Cl mg/L 13 0.50 2.0 8.0 1.3 3.4

Hardness mg CaCO3/L NA 1.0 7.0 28 5.0 9.0

TSS mg/L NA 2.5 5.0 70 2.5 10

Turb. NTU NA 1.3 7.2 41 3.60 14



7.3.3 Key Beneficial Values and Uses

The identified beneficial use, as defined under the Water Act (1992), is the “protection of aquatic ecosystems”. Broadly this covers water quality and all biota, such as macroinvertebrates, vertebrates (fish, amphibians and reptiles), algae, aquatic flora and their habitats.

For the purposes of this ERA, and when considering potential threats to this value, the most sensitive broad biota group/s have been taken into account. Based on GHD’s understanding of the range of biota present in Pine Creek and Copperfield Creek, the following taxa are considered to be representative of those most sensitive to toxic metals and other deleterious water quality parameters:

Macroinvertebrates in the order Cladocera (water fleas) such as Daphnia and Moino species.

Macroinvertebrates in the genus Hydra and Macrobrachium (freshwater prawns).

Aquatic plants such as Lemna (duckweed).

Microalgae.

7.3.4 Quality of the water at the Authorised Discharge Points

Pine Creek – Authorised Discharge Point

Summary water quality data measured from the discharge location on Pine Creek, PCCK04 is presented in Table 7-3. The discharge quality can be characterised by high electrical conductivity and high concentrations of cadmium, cobalt, nickel and zinc, with super-saturation of dissolved oxygen and turbid conditions.


Table 7-3 PCCK04 Pine Creek (Authorised Discharge Point) Data Summary (2012 to 2014) and ISSTVs


80th Percentile

pH 6.0-7.5 5.6 6.2 6.7 6.0 6.5

EC µS/cm 20-250 64 229 557 165 292

DO % 35-120 40 109 183 81 132

TDS mg/L NA 38 134 377 98 195

Al µg/L 508 5 31 50 16 43

As µg/L 140 0.50 2.0 5.0 0.90 3.0

Cd µg/L 0.80 0.05 0.95 1.4 0.44 1.2

Co µg/L 2.8* 0.50 14 34 3.6 27

Cr µg/L 40 0.50 0.50 0.50 0.50 0.50

Cu µg/L 5 0.50 3.0 5.0 1.8 4.2

Fe µg/L 300* 16 54 100 32 73

Pb µg/L 9.4 0.50 0.50 0.50 0.50 0.50

Mn µg/L 3600 30 405 1300 188 1120

Ni µg/L 17 0.50 13 35 8 30

Se µg/L 34 0.50 0.50 0.50 0.50 0.50

Zn µg/L 31 23 510 1200 314 1100

Ca mg/L NA 4.5 6.15 15 4.7 11

K mg/L NA 1.70 2.15 2.80 1.86 2.34

Na mg/L NA 3.90 6.05 13.00 4.54 8.72

Mg mg/L NA 7.7 12.5 32.0 8.9 25.0

HCO3 mg/L NA 3 15 130 11 38

CO3 mg/L NA 3 3 3 3 3

Alk. mg/L NA 3 15 130 11 38

SO4 mg/L NA 13 66 190 43 130

Cl mg/L 13 2 3 7 2 5

Hardness. mgCaCO3/L NA 46 68 170 48 134

TSS mg/L NA 3 8 29 3 17

Turb. NTU 2-15 0.70 8 30 2 19



Copperfield Creek – Authorised Discharge Point

Summary water quality data measured from, PCPWD is presented in Table 7-4. The discharge quality can be characterised by high electrical conductivity, high concentrations of aluminium, cadmium, cobalt, copper, lead, manganese, nickel, zinc and chloride with super-saturation of dissolved oxygen, turbid conditions and acidic water.

Table 7-4 PCPWD Copperfield Creek (Authorised Discharge Point) Data Summary (2010 to 2014) and ISSTVs

PCPWD ISSTV Min Median Max 20th Percentile

80th Percentile

pH 6.0-7.5 3.4 4.4 5.9 4.1 4.8

EC µS/cm 20-250 3.9 1627 4402 1200 2407

DO % 45-120 2.3 74 150 52 125

TDS mg/L NA 67 962 1944 683 1468

Al µg/L 590 300 2700 13000 1400 5064

As µg/L 140 2.0 7.0 18 5.0 9.6

Cd µg/L 0.8 7.20 23 77 13 35

Co µg/L 2.8* 160 420 1020 280 660

Cr µg/L 40 0.50 0.50 6.00 0.50 0.50

Cu µg/L 2.5 4.00 55 230 27 104

Fe µg/L 300* 31 110 620 67 220

Pb µg/L 9.4 3.00 15 39 9.00 28

Mn µg/L 3600 38.30 14000 25000 8700 18600

Ni µg/L 17 100 290 710 160 386

Se µg/L 34 0.50 0.50 4.00 0.50 0.50

Zn µg/L 95 7500 22000 53000 13000 29000

Ca mg/L NA 17 55 100 36 75

K mg/L NA 2.50 7.60 16 5.08 11

Na mg/L NA 4.8 85 190 44 140

Mg mg/L NA 13 150 270 108 210

HCO3 mg/L NA 0.05 2.50 140 0.50 2.5

CO3 mg/L NA 0.05 2.5 6.0 0.50 2.5

Alk. mg/L NA 0.05 2.5 150 0.50 2.5

SO4 mg/L NA 23 900 1700 600 1300

Cl mg/L 13 4.00 13 1500 9.0 19

Hardness mgCaCO3/L NA 57 710 1400 508 1000

TSS mg/L NA 2.5 2.5 1000 2.5 16

Turb. NTU NA 0.50 2.2 110 0.94 16 * Denotes no ISSTV and ANZECC (2000) low reliability trigger value used NA denotes no ISSTV or ANZECC (2000) trigger value Dark grey shading denotes exceedance of ISSTV


7.4 Factors that Influence Impacts

Metal contaminants can be directly toxic to aquatic life but the degree of toxicity depends on numerous biological factors such as life stage and tolerance level as well as other chemical factors including the presence of other compounds or pH. The toxicity of contaminants can also be exacerbated by other stressors such as flow related disturbances following heavy rain events (Walsh et al. 2004). Biological impacts can be difficult to assess due to the potential (and often poorly understood) cumulative impacts of multiple elevated metals and/or other water quality changes. For example, higher water temperatures increase the absorption of trace metals, and therefore their toxicity (Dallas and Day 1993). Toxicity of heavy metals needs to consider direct impacts and indirect impact such as bio-accumulation. Accumulation in the food chain has the potential to have both short term and long term effects (EPA 1995).

7.4.1 Water Quality Monitoring Data and Interim Site Specific Trigger Values

Surface water monitoring is undertaken across a range of sites up and downstream of the Pine Creek and Copperfield Creek discharge points. CGAO conducted water quality monitoring of Pine Creek and Copperfield Creek in accordance with WDL-166-02 from 2010 to 2014. In order to compare the CGAO monitoring data with the 2013/14 ISSTV, the 20th and 80th percentile for pH and 80th percentile for all other analytes in these data sets have been used to identify potential stressors.

It must be noted that the ISSTVs listed in WDL 166-02 are to be applied to sites PCCK03 and PCCK06 for compliance only. However, they have been used in this risk assessment for comparative purposes and to assess risk downstream of the discharge points.

Pine Creek – Downstream Sites

At downstream site PCCK02, 80th percentile data indicates electrical conductivity, cadmium, cobalt, copper, nickel, zinc and turbidity exceeded the 2013/14 ISSTV (Table 7-5). Median values indicate that cadmium, cobalt, zinc and nickel exceed the 2013/14 ISSTVs.

At downstream site PCCK03, 80th percentile data indicates dissolved oxygen (super saturated), cobalt, zinc and turbidity exceeded the 2013/14 ISSTV (Table 7-6). Median values indicate that cobalt and zinc exceed the 2013/14 ISSTVs.

Copperfield Creek – Downstream Sites

At downstream site PCCK06, the 80th percentile data indicates cadmium, cobalt, iron, zinc and turbidity exceeded the 2013/14 ISSTV (Table 7-7). Median values indicate that iron exceeds the 2013/14 ISSTV.

At downstream site PCCK06B, 80th percentile data indicates iron, zinc, and turbidity exceeded the 2013/14 ISSTV (Table 7-8). Median values indicate iron exceeds the 2013/14 ISSTV.

At downstream site PCCK21, dissolved oxygen (supersaturated), iron, zinc and turbidity exceeded the 2013/14 ISSTV (Table 7-9). All median values were within acceptable 2013/14 ISSTVs.


Table 7-5 PCCK02 Pine Creek (downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs


80th Percentile

pH 6.0-7.5 4.4 6.3 7.6 6.1 6.6

EC µS/cm 20-250 56 195 1831 155 332

DO % 35-120 11 67 165 30 111

TDS mg/L NA 35 115 312 100 217

Al µg/L 508 5 50 3700 9 158

As µg/L 140 0.50 3.0 13 2.0 4.0

Cd µg/L 0.80 0.05 1.0 7.3 0.58 1.5

Co µg/L 2.8* 0.39 16 96 5.6 26

Cr µg/L 40 0.50 0.50 0.50 0.50 0.50

Cu µg/L 5 0.50 3.0 53 2.0 5.0

Fe µg/L 300* 12 87 500 51 260

Pb µg/L 9.4 0.50 0.50 15 0.50 1.0

Mn µg/L 3600 0.65 510 2300 198 814

Ni µg/L 17 1 18 74 7 25

Se µg/L 34 0.10 0.50 0.50 0.50 0.50

Zn µg/L 31 24 700 4000 294 932

Ca mg/L NA 1.6 5.5 22 4.4 9.6

K mg/L NA 1.20 1.95 6.40 1.60 2.24

Na mg/L NA 2.60 5.40 11.00 4.22 7.54

Mg mg/L NA 2.70 11 51 8.38 21

HCO3 mg/L NA 0.05 11 140 6.80 20

CO3 mg/L NA 0.05 0.50 8.00 0.50 2.5

Alk. mg/L NA 0.05 11 150 6.80 20

SO4 mg/L NA 11 56 260 41 114

Cl mg/L 13 1 3 7 2 3

Hardness mgCaCO3/L NA 15 56 270 46 110

TSS mg/L NA 2.5 5.5 90 2.5 9.2

Turb. NTU 2-15 0.90 5.8 24 2.7 17



Table 7-6 PCCK03 Pine Creek (Compliance Point/downstream) Data Summary (2012 to 2014) and 2013/2014 ISSTVs


80th Percentile

pH 6.0-7.5 5.6 6.3 7.2 6.1 6.6

EC µS/cm 20-250 72 159 365 127 219

DO % 35-120 55 109 135 68 120

TDS mg/L NA 45 94 241 74 131

Al µg/L 508 5 20 680 5 50

As µg/L 140 1.0 2.0 7.0 2.0 4.0

Cd µg/L 0.80 0.05 0.20 0.80 0.10 0.50

Co µg/L 2.8* 0.50 4.0 11 2.0 7.0

Cr µg/L 40 0.50 0.50 0.50 0.50 0.50

Cu µg/L 5 0.50 2.0 4.0 0.50 2.0

Fe µg/L 300* 18 50 470 37 140

Pb µg/L 9.4 0.50 0.50 0.50 0.50 0.50

Mn µg/L 3600 95 210 540 150 380

Ni µg/L 17 2.0 7.0 16 5.0 11

Se µg/L 34 0.5 0.5 0.5 0.5 0.5

Zn µg/L 31 39 290 590 170 320

Ca mg/L NA 2.9 5.6 12 4.5 8.0

K mg/L NA 1.8 2.1 2.5 1.9 2.3

Na mg/L NA 3.9 5.3 8.0 4.4 6.9

Mg mg/L NA 5.1 10 24 7.0 16

HCO3 mg/L NA 9.0 17 98 12 20

CO3 mg/L NA 2.5 2.5 2.5 2.5 2.5

Alk. mg/L NA 9 17 98 12 20

SO4 mg/L NA 21 61 140 30 100

Cl mg/L 13 2.0 3.0 3.0 2.0 3.0

Hardness. MgCaCO3/L NA 28 56 130 38 86

TSS mg/L NA 2.5 7.0 27 2.5 26

Turb. NTU 2-15 0.80 8.4 44 2.7 19



Table 7-7 PCCK06 Copperfield Creek (Compliance Point/downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs


80th Percentile

pH 6.0-7.5 4.3 6.5 7.6 6.2 6.8

EC µS/cm 20-250 19 115 1012 57 209

DO % 45-120 6.5 78 153 56 116

TDS mg/L NA 20 55 3575 33 131

Al µg/L 590 5.0 49 1301 20 248

As µg/L 140 0.50 1.0 62 0.50 2.0

Cd µg/L 0.8 0.05 0.05 18 0.05 1.2

Co µg/L 2.8* 0.50 0.50 230 0.50 20

Cr µg/L 40 0.50 0.50 0.50 0.50 0.50

Cu µg/L 2.5 0.50 1.0 49 0.50 2.0

Fe µg/L 300* 71 450 1600 262 830

Pb µg/L 9.4 0.50 0.50 7.0 0.50 0.50

Mn µg/L 3600 2.5 48 6200 16 606

Ni µg/L 17 0.50 1.0 170 0.50 13

Se µg/L 34 0.50 0.50 3.0 0.50 0.50

Zn µg/L 95 3.00 60 12000 14 940

Ca mg/L NA 0.50 1.30 29 0.80 3.3

K mg/L NA 1.0 1.8 4.2 1.4 2.2

Na mg/L NA 0.05 5.60 43 4.60 7.40

Mg mg/L NA 0.80 2.00 81 1.40 8.60

HCO3 mg/L NA 0.05 19 45 14 24

CO3 mg/L NA 0.05 2.5 45 0.50 2.50

Alk. mg/L NA 0.05 19 45 14 24

SO4 mg/L NA 0.25 2.2 510 0.50 41

Cl mg/L 13 0.50 2.0 8.8 2.0 3.4

Hardness.mg CaCO3/L NA 2.5 11 400 7.2 36

TSS mg/L NA 2.5 5.0 79 2.5 15

Turb. NTU NA 2.5 10 64 4.9 24



Table 7-8 PCCK06B Copperfield Creek (downstream) Data Summary (2010 to 2014) and 2013/2014 ISSTVs

PCCK06B ISSTV Min Median Max 20th Percentile

80th Percentile

pH 6.0-7.5 5.9 6.8 8.9 6.5 7.0

EC µS/cm 20-250 25 62 297 44 112

DO % 45-120 15 65 139 46 88

TDS mg/L NA 23 39 179 29 48

Al µg/L 590 5.00 65 350 34 164

As µg/L 140 0.50 1.0 2.0 0.50 2.0

Cd µg/L 0.8 0.05 0.05 2.20 0.05 0.60

Co µg/L 2.8* 0.50 0.50 20 0.50 6.0

Cr µg/L 40 0.50 0.50 0.50 0.50 0.50

Cu µg/L 2.5 0.50 1.5 6.0 0.50 2.0

Fe µg/L 300* 100 630 1200 252 860

Pb µg/L 9.4 0.50 0.50 0.50 0.50 0.50

Mn µg/L 3600 11 47 720 19 224

Ni µg/L 17 0.50 0.50 16 0.50 6.4

Se µg/L 34 0.50 0.50 0.50 0.50 0.50

Zn µg/L 95 22 49 1300 33 388

Ca mg/L NA 0.50 1.2 4.8 0.80 2.7

K mg/L NA 1.2 1.8 2.8 1.3 2.1

Na mg/L NA 1.1 5.4 11.0 4.7 6.7

Mg mg/L NA 1.0 1.8 11 1.5 6.0

HCO3 mg/L NA 0.50 23 35 16 26

CO3 mg/L NA 0.50 2.5 2.5 0.50 2.5

Alk. mg/L NA 0.50 23 35 16 26

SO4 mg/L NA 0.50 2.0 67 0.60 24

Cl mg/L 13 1.0 2.0 6.0 2.0 3.8

Hardness mgCaCO3/L NA 5.0 10 55 8.0 31

TSS mg/L NA 2.5 6.0 24 2.5 12

Turb. NTU NA 4.3 13 33 7.8 26



Table 7-9 PCCK21 Copperfield Creek (downstream) Summary Data (2010 to 2014) and ISSTVs


80th Percentile

pH 6.0-7.5 6.3 6.6 7.4 6.5 7.1

EC µS/cm 20-250 23 61 119 51 78

DO % 45-120 17 86 148 49 127

TDS mg/L NA 14 40 63 32 48

Al µg/L 590 5 80 1300 27 252

As µg/L 140 0.50 0.50 43 0.50 1.0

Cd µg/L 0.8 0.05 0.05 0.20 0.05 0.05

Co µg/L 2.8* 0.50 0.50 2.0 0.50 0.50

Cr µg/L 40 0.50 0.50 1.00 0.50 0.50

Cu µg/L 2.5 0.50 0.50 4.00 0.50 1.2

Fe µg/L 300* 96 240 480 178 334

Pb µg/L 9.4 0.50 0.50 0.50 0.50 0.50

Mn µg/L 3600 12 35 190 19 96

Ni µg/L 17 0.50 1.0 3.0 0.50 2.00

Se µg/L 34 0.50 0.50 0.50 0.50 0.50

Zn µg/L 95 9.0 39 190 21 65

Ca mg/L NA 0.25 1.6 6.3 1.0 2.1

K mg/L NA 1.3 1.5 2.7 1.4 1.8

Na mg/L NA 1.6 5.7 9.1 4.1 7.6

Mg mg/L NA 0.25 2.2 5.9 1.5 2.7

HCO3 mg/L NA 8.00 28 45 22 37

CO3 mg/L NA 0.05 2.5 2.5 0.50 2.5

Alk. mg/L NA 8.00 28 45 22 37

SO4 mg/L NA 0.50 2.0 21 0.50 5.0

Cl mg/L 13 0.50 1.0 3.00 1.0 2.0

Hardness mg CaCO3/L NA 1.5 13 33 9 17

TSS mg/L NA 2.5 8.00 120 2.5 22

Turb. NTU NA 4.2 14 160 7.8 30



7.4.2 Threats

The risk assessment process identifies threats as the water quality parameters that are likely to cause negative impacts to aquatic values.

Threats are based on the water quality parameters that were analysed for the discharge point sites PCCK04 and PCPWD water quality monitoring program undertaken by CGAO between 2010 and 2014. Threats were screened to identify water quality analytes that were considered low risk. The screening process calculated percentiles for all analytes. In accordance with ANZECC (2000) the 80th percentile was used as the data value to screen analytes against the 2013/14 ISSTV. Water quality analytes for which the 80th percentile is below the ISSTV (or the 20th and 80th percentiles were within the ISSTV range, in the case of pH), were considered to pose a low risk to aquatic values

The water quality analytes above the 80th percentile were taken through the full risk assessment process.

The key potential stressors presented in the Pine Creek discharge (PCCK04) are:

electrical conductivity

cadmium

cobalt

nickel

zinc

dissolved oxygen

turbidity

The key potential stressors presented in the Copperfield Creek discharge (PCPWD) are:

electrical conductivity

aluminium

cadmium

cobalt

copper

lead

manganese

nickel

zinc

chloride

dissolved oxygen

turbidity

pH

This screening process assumes that threats for which the 80th percentile are below the ISSTV would pose a low risk. However, it is possible that some of these threats still occasionally exceed the ISSTV, and may have the potential to have a low-level impact on values.


7.4.3 Risk Analysis Method

The risk analysis assesses the potential risk posed by the mine discharge to the aquatic values at Pine Creek and Copperfield Creek in the vicinity of sampling sites listed in WDL-166-02. This phase of the assessment involves the development of a risk assessment method and risk register based on the water quality monitoring data and waterway conditions.

The AVIRA method consists of three components including:

Defining consequence descriptors for the values identified.

Defining a threat score for individual water quality analytes.

Determining the level of association of the threat/benefit to the beneficial use or value.

These steps are outlined in further detail in the following sections.

7.4.4 Defining Consequence Descriptors for the Value

This risk assessment uses a semi quantitative assessment and has a modified consequence (or impact) component accommodate the impacts to the beneficial use. Consequence of impact descriptors were defined on a scale of one to five where one represented little or no impact and five was a significant impact. Consequence scores were allocated for each risk based on the level of bioavailability of the toxicants and our understanding of the condition of aquatic biota in Pine Creek and Copperfield Creek.

The descriptors were developed for the beneficial use, are based on aquatic populations (encompassing aquatic flora and fauna) and are provided in Table 7-10 below.

Table 7-10 Descriptors of Impact Magnitude

Score Magnitude of Impact Aquatic Values

1 Insignificant <5 percent decline in aquatic populations

2 Low 5-10 percent decline in aquatic populations

3 Moderate >10-20 percent decline in aquatic populations

4 High >20-50 percent decline in aquatic populations

5 Extreme >50 percent decline in aquatic populations

7.4.5 Development of Threat Scores

Threat scores provide an indication of the potential for an analyte to impact a beneficial use or value, i.e. the higher the score the greater the likelihood of an impact.

Table 7-11 shows how the threat score ranking was determined for metals. For pH and dissolved oxygen the ranking was based on the exceedance occurring either over or under the ISSTV and used values that were realistic for these parameters scales, i.e. pH 5.0 to 9.0 and dissolved oxygen 10 to 160 percent.


Table 7-11 Threat Score Ranking

Score Threat Score Ranking

5 >5 x Interim Site Specific Trigger Value

4 >2 x Interim Site Specific Trigger Value – 5 x Interim Site Specific Trigger Value

3 > Interim Site Specific Trigger Value – 2 x Interim Site Specific Trigger Value

2 >0.5 x Interim Site Specific Trigger Value – Interim Site Specific Trigger Value

1 ≤0.5 x Interim Site Specific Trigger Value

Threat scores of each of the key identified threats are provided in Table 7-12 for Pine Creek with Table 7-13 for Copperfield Creek. Red bold text indicates where the 80th percentile of the measured values of the threat was in exceedance of the relevant ISSTV.

Table 7-12 Threat Scores PCCK04

Score EC Cd Co Ni Zn DO* Turb.

5 >1250 >4 >14 >85 >155 <10 or >160 >75

4 >440-1250 >1.6-4.0 >5.6-14 >34-85 >62-155 <30 or 140-160 >30-75

3 >250-440 >0.8-1.6 >2.8-5.6 >17-34 >31-62 >120-140 >15-30

2 >125-205 >0.4-08 >1.4-2.8 >8.5-17 >15.5-31 >100-120 >7.5-15

1 ≤125 ≤0.4 ≤1.4 ≤8.5 ≤15.5 ≤35-100 ≤7.5


Table 7-13 Threat Scores PCPWD

Score EC Al Cd Co Cu Pb Mn Ni Zn Cl DO* pH*

5 >1250 >2950 >4 >14 >12.5 >47 >18000 >85 >475 >65 <10 or >160 <5.0 or >9.0

4 >440-1250 >1180-2950 >1.6-4 >5.6-14 >5-12.5 >18.8-47 >7200-18000 >34-85 >190-475 >26-65 <30 or

140-160

5.0-<5.5 or

>8.5-9.0

3 >250-440 >590-1180 >0.8-1.6 >2.8-5.6 >2.5-5 >9.4-18.8 >3600-7200 >17-34 >95-190 >13-26 >120-140 5.5-<6.0 or

>8.0-8.5

2 >125-205 >295-590 >0.4-08 >1.4-2.8 >1.25-2.5 >4.7-9.4 >1800-3600 >8.5-17 >47.5-95 >6.5-13 >100-120 6.0-<6.5 or

>7.5-8.0

1 ≤125 ≤295 ≤0.4 ≤1.4 ≤1.25 ≤4.7 ≤1800 ≤8.5 ≤47.5 ≤6.5 ≤35-100 6.0-7.5

Threats scores have also been calculated for the compliance monitoring points PCCK03 and PCCK06. The discharge points have been chosen to use in the risk assessment rather than the compliance points to assessment for the worst case scenario. However, threat scores for the compliance points have been calculated to demonstrate the threats at the compliance points. Threat scores for PCCK03 are presented in Table 7-14 and threat scores for PCCK06 are presented in Table 7-15.



Score Co Zn DO Turb

5 >14 >155 <10 or >160 >75

4 >5.6-14 >62-155 <30 or 140-160 >30-75

3 >2.8-5.6 >31-62 120-140 >15-30

2 >1.4-2.8 >15.5-31 100-120 >7.5-15

1 ≤1.4 ≤15.5 35-100 ≤7.5


Score Cd Co Fe Zn

5 >4 >14 >1500 >475

4 >1.6-4 >5.6-14 >600-1500 >190-475

3 >0.8-1.6 >2.8-5.6 >300-600 >95-190

2 >0.4-08 >1.4-2.8 >150-300 >47.5-95

1 ≤0.4 ≤1.4 ≤150 ≤47.5

7.4.6 Determining the level of association of the threat to the beneficial use or value

The term “association” is used to define the strength of the linkage between the threat and the beneficial use or value. Association identifies the level of influence a threat may have on a value, and is rated low, medium or high.

For the purposes of this ERA, the parameters that have been identified as threats (aluminium, cadmium, copper, lead, nickel and zinc) have all been allocated a high association. The metals have a high association due to the direct toxicity they present to aquatic biota. Cobalt, manganese, chloride, electrical conductivity, turbidity and dissolved oxygen have been allocated a medium association. Furthermore, pH has been given a high association, due to its direct relationship to metal mobilisation and toxicity (the lower the pH, the higher the metal toxicity).

7.5 Phase 2 – Risk Analysis

The risk analysis identified a range of low and medium and high risks.

The focus of the risk assessment was to assign impact scores for each of the identified beneficial uses to threat relationships (associations) identified during the earlier stages of the risk assessment.

Scores were based on the threat tables defining levels of impact and CGAO’s water quality monitoring data collated and analysed for site PCCK04 and site PCPWD separately.

A summary of the risks calculated for PCCK04 provided in Table 7-16 and Table 7-17 for PCPWD.


Table 7-16 Pine Creek Summary of Risks

Inherent Risk - Current Situation

Beneficial Use

Spatial Extent

Threat Cons Score

Comments Association Threat/ Enhancer

Risk Score

Protection of aquatic ecosystems

PCCK04 Cadmium 2

Cadmium is easily absorbed by organisms can cause toxic effects at low concentrations (Dallas and Day 2004). However, the toxicity of cadmium is reduced under certain conditions including high concentrations of chloride (ANZECC 2000).

High 3 L


PCCK04 Nickel 2 Nickel can be toxic even in small quantities interfering with enzymes and the citric acid cycle and has been shown to be a carcinogen in some mammals (Dallas and Day 2004).

High 4 M


PCCK04 Zinc 2 Trace metals such as copper and zinc are toxic at extremely low concentrations and may act together to suppress algal growth and affect fish and benthos (Hoehn and Sizemore, 1977).

High 5 H


PCCK04 Dissolved Oxygen 1

Dissolved oxygen is essential for all aquatic plants and animals and although not directly toxic, its effects can cause dramatic changes to ecosystems (Dallas and Day 2004). Oxygen levels in excess of 110 % saturation are indicative of eutrophic conditions (Tiller and Newall 2009) or can be chemically induced (Dallas and Day 2004). Supersaturated conditions harm fish gills and result in mortality (Dallas and Day 2004). Although aquatic organisms can generally sustain low oxygen conditions for a short period, sustained conditions will result in morality of species (Tiller and Newall 2009). Furthermore low oxygen conditions can result in the production of hydrogen sulphide which is highly toxic (Tiller and Newall 2009).

Medium 3 L


PCCK04 Cobalt 1

Water quality guidelines developed using statistical distribution methods for cobalt in freshwater are particularly conservative, existing well above some experimental chronic concentrations (including LC50 of 27µg/L). While some aquatic organisms may accumulate cobalt, it is not highly toxic and in small concentrations it is an essential trace element required by most aquatic organisms (ANZECC 2000) and generally cobalt is not considered to be an ecotoxic trace metal (Dallas and Day 2004).

Medium 5 L



Beneficial Use

Spatial Extent

Threat Cons Score


Risk Score


PCCK04 Electrical Conductivity 1

Electrical conductivity above 1,500 µS/cm is considered a threshold above which impacts to freshwater species could be expected (Tiller. and Newall 2009). However, R. Krassoi has shown that, in laboratory testing, Australian species are not impacted below 3,500 µS/cm (pers. comm.) If salinity in a freshwater environment becomes too high the diversity and abundances of organisms is reduced (Hart et al., 1991). Concentrations may also impact by acting as a barrier to fish migration.

Medium 3 L


PCCK04 Turbidity 1

Increased turbidity and suspended sediment can strongly impact ecological processes through a number of mechanisms, by altering predator-prey interactions through reduced visibility, clogging the gills of fish, invertebrates and other fauna, reducing light penetration (and therefore photosynthetic potential of underwater plants) and smothering benthic (i.e. river bed) habitats as the sediment settles (Ryan 1991 and references therein). There is some limited information relating to turbidity tolerances of freshwater ecosystems, however, these appear to be largely dependent on the background level of turbidity to which that each system is adapted.

Medium 3 L


Table 7-17 Copperfield Creek summary of risks


Beneficial Use

Spatial Extent

Threat Cons Score


Risk Score


PCPWD Aluminium 2 Aluminium is considered to be one of the more toxic metals but is highly dependent on pH (Dallas and Day 2004). High 5 H


PCPWD Cadmium 2

Cadmium is easily absorbed by organisms can cause toxic effects at low concentrations (Dallas and Day 2004). However, the toxicity of cadmium is reduced under certain conditions including high concentrations of chloride (ANZECC 2000).

High 5 H


PCPWD Copper 2 Trace metals such as copper and zinc are toxic at extremely low concentrations and may act together to suppress algal growth and affect fish and benthos (Hoehn and Sizemore 1977).

High 5 H


PCPWD Lead 2 Lead is considered to be toxic and will accumulate in the tissues of organisms (Dallas and Day 2004). High 4 M


PCPWD Nickel 2 Nickel can be toxic even in small quantities interfering with enzymes and the citric acid cycle and has been shown to be a carcinogen in some mammals (Dallas and Day 2004).

High 5 H


PCPWD Zinc 2 Trace metals such as copper and zinc are toxic at extremely low concentrations and may act together to suppress algal growth and affect fish and benthos (Hoehn and Sizemore 1977).

High 5 H


PCPWD pH 2

Increased acidity (i.e. reduced pH) can impact directly upon algae and macroinvertebrates, resulting in the loss of algae and other primary producers and thereby reducing the food available to herbivorous macro-invertebrate species (Courtney and Clements 2002). Low pH also influences macro-invertebrates through disruptions of ionic balance across the organism’s membranes (Jarvis and Younger 1997). There can be a subsequent flow-on effect with a reduction in macroinvertebrates (an important part of the food web) resulting in a reduction in food source for higher trophic level organisms such as predatory macroinvertebrates, fish and reptiles such as turtles and crocodiles. Organisms such as snails with calcium carbonate shells are likely to have their shell dissolved in acidic waters (Kelly 1988). Increased acidity of mine waters also increases the bioavailability of metals (Cherry et al. 2001) resulting in greater toxicity. This may then lead to the accumulation of metals in organisms.

High 5 H



Beneficial Use

Spatial Extent

Threat Cons Score


Risk Score


PCPWD Dissolved Oxygen 1

Dissolved oxygen is essential for all aquatic plants and animals and although not directly toxic, its effects can cause dramatic changes to ecosystems (Dallas and Day 2004). Oxygen levels in excess of 110 % saturation are indicative of eutrophic conditions (Tiller and Newall 2009) or can be chemically induced (Dallas and Day). Supersaturated conditions harm fish gills and result in mortality (Dallas and Day 2004). Although aquatic organisms can generally sustain low oxygen conditions for a short period, sustained conditions will result in morality of species (Tiller and Newall 2009). Furthermore low oxygen conditions can result in the production of hydrogen sulphide which is highly toxic (Tiller and Newall 2009).

Medium 3 L


PCPWD Cobalt 1

Water quality guidelines developed using statistical distribution methods for cobalt in freshwater are particularly conservative, existing well above some experimental chronic concentrations (including LC50 of 27µg/L). While some aquatic organisms may accumulate cobalt, it is not highly toxic and in small concentrations it is an essential trace element required by most aquatic organisms (ANZECC 2000) and generally cobalt is not considered to be an ecotoxic trace metal (Dallas and Day 2004).

Medium 5 L


PCPWD Manganese 1 Manganese can be toxic to aquatic biota. However, compared to other metals its toxicity is low (ANZECC 2000). Medium 2 L


PCPWD Chloride 1 Chloride is a major ion found naturally in waterways and does not have direct toxic impacts on biota (Dallas and Day 2004). Medium 5 L


PCPWD Electrical Conductivity 1

Electrical conductivity above 1,500 µS/cm is considered a threshold above which impacts to freshwater species could be expected (Tiller and Newall 2009). However, R. Krassoi has shown that, in laboratory testing, Australian species are not impacted below 3,500 µS/cm (pers. comm.) If salinity in a freshwater environment becomes too high the diversity and abundances of organisms is reduced (Hart et al., 1991). Concentrations may also impact by acting as a barrier to fish migration

Medium 3 L


7.6 Phase 3 – Risk Characterisation

7.6.1 Basis for the Risk Characterisation

Risk characterisation considers the key risks that water quality poses to the aquatic ecosystem of Pine Creek and Copperfield Creek in the context of the objectives of the project.

In carrying out the risk assessment, it is noted:

The risks to beneficial use and values were assessed for the area in the vicinity of water quality sampling sites listed in WDL 166-02.

If the 80th percentile of an analyte from the water quality data did not exceed the Interim Site Specific Trigger Value (ISSTV), it was considered to be a low risk to the aquatic ecosystem and was not included in the risk assessment process.

The risk assessment does not identify actual impacts to aquatic species. Instead it identifies a level of risk posed by a particular threat on ecological values. Levels of risk are identified through an assessment of potential sensitivity of values to particular threats and the level of the threat in the receiving environment.

The assessment of threat associated with the range of analytes sampled in Crocodile Gold’s water quality monitoring program has been based on calculation of 80th percentiles of measured values for data at site PCCK04 and site PCPWD. This provided a realistic assessment of water quality data at the site and aligned with approaches defined by ANZECC (2000).

7.7 Discussion

The risks to the beneficial use and values were assessed for the area of Pine Creek and Copperfield Creek in the vicinity of surface water monitoring sites PCCK04 and PCPWD. The risk assessment identified:

At PCCK04, zinc poses a high risk, nickel a medium risk and cadmium, dissolved oxygen, cobalt, electrical conductivity and turbidity a low risk to the aquatic ecosystem of Pine Creek.

At PCPWD, aluminium, cadmium, copper, nickel, zinc, pH pose a high risk, lead a medium risk and dissolved oxygen, cobalt, manganese, chloride and electrical conductivity a low risk to the aquatic ecosystem of Copperfield Creek.

Scores were assigned conservatively, taking onto account the most sensitive biota such as microalgae and macroinvertebrates.

It is also evident that the water quality at Pine Creek in sites downstream of PCCK04 has elevated concentrations of the parameters identified to pose a risk to the aquatic ecosystem of Pine Creek. Cadmium, nickel and zinc were all above ISSTVs at the furthest downstream monitoring site PCCK03. However, median values were all below ISSTVs at the compliance point PCCK03 with the exception of cobalt and zinc. Parameters at downstream sites have higher levels of the contaminants compared to upstream at PCCK01, with the exception of turbidity, which indicates that the biota of Pine Creek are already exposed to turbid conditions despite the water quality PCCK04.

Additionally, at the compliance point on Pine Creek, PCCK03, threat scores were calculated for the identified potential stressors using 80th percentile data, cobalt, zinc, dissolved oxygen and turbidity. This is a reduced set of parameters and thus reduced risk compared to point PCCK04. Threat scores for PCCK03 indicate that zinc has a threat score of 5, cobalt 4 and dissolved oxygen and turbidity 3, with cobalt having a lower threat score at PCCK03 than that of point PCCK04.


It is evident that the water quality at Copperfield Creek in sites downstream of PCPWD has elevated concentrations of the parameters identified to pose risk to the aquatic ecosystem of Copperfield Creek. However, it is also apparent that some of these parameters dilute below the ISSTVs in downstream sites, so that by the furthest downstream site PCCK21 only zinc, dissolved oxygen and turbidity are above the ISSTVs. Dissolved oxygen and turbidity fluctuate throughout the downstream sites, and non-compliance with the ISSTVs may be more related to individual sites habitat conditions rather than the water quality of PCPWD. Nonetheless, when median values of all potential stressors are compared to the ISSTVs at site PCCK21 these are all compliant suggesting low risk.

Furthermore, at the compliance point on Copperfield Creek, PCCK06, threat scores were for the identified potential stressors using 80th percentile data, cadmium, cobalt, iron and zinc. Iron was also the only parameter to exceed the 2013/14 ISSTV when compared against median values. As iron was not identified as a potential stressor at the point PCPWD this suggest iron entering the waterway between PCPWD and PCCK06. Threat scores for PCCK06 indicate that cadmium has a threat score of 3, cobalt 3, iron 4 and zinc 5, with cadmium having a lower threat score than the PCPWD point and iron newly identified as a stressor.

7.8 Conclusions

This risk assessment took a semi-quantitative and conservative approach to assess the risks to the beneficial use and values for the area of Pine Creek and Copperfield Creek in the vicinity of surface water monitoring sites PCCK04 and PCPWD. The risk assessment identified:



However, water quality at the compliance points PCCK03 and PCCK06 suggests the risks posed by these parameters may not be as high as the risk assessment suggests. Furthermore, there is evidence of dilution of these parameters further downstream in both Pine Creek and Copperfield Creek. It is also apparent the water quality in both study reaches is influenced by elevated iron, which is high in upstream sites.


8. Conclusions 8.1 General

The long term water quality results show that the water quality in PCPWD is improving with an increase in pH and decrease in bioavailable metals. The ecotoxicology data from 2009 and 2013 support this, however, neither sample tested was representative of median water quality in PCPWD.

A decrease in pH at PCCK04 was observed during the 2013/14 wet season. This decrease is possibly sourced from NW WRD and backfilled International Pit seepages. Monitoring should continue at this site and further investigations should be conducted if the pH continues to decrease.

Sediment results show that zinc is present in sediments above the ISQGs. The presence of zinc in the sediments is related to the high zinc concentrations in PCPWD and at PCCK04 adsorbing to the sediments downstream of the discharges. The ecotoxicology results show that toxicity is observed at PCCK06, PCCK06B and PCCK03 which can be attributed to the zinc concentrations at those sites. These results agree with the risk assessment which also detects that zinc is a high risk at PCCK06 and PCCK03, with other metals a lower risk. However, the Copperfield Creek far downstream site PCCK21 does not show any toxicity.

Even though toxicity at downstream sites was detected in the laboratory organisms, the in-situ macroinvertebrate results show that there were no significant differences in any of the univariate macroinvertebrate indices between Control site and Impact site sample groups. There was, however, significant year to year variation in Abundance, Taxa Richness and PET Richness. The latter related mainly to the very low diversity and abundance of macroinvertebrate fauna collected in 2012 and the high abundance and diversity of macroinvertebrate fauna collected in 2013.

The SSTVs calculated in this report are to be applied to the designated downstream sites for the 2014/15 wet season and then these can be recalculated using 2014/15 data for use in the next wet season. To enable better management of discharge water to meet SSTVs downstream of the discharge in Copperfield Creek a system which allows greater control of water leaving PCPWD is required.

8.2 Water Quality

8.2.1 General

No significant trends were observed for any analytes at any sites. This is due to the variability of water quality at each site caused by the wet/dry season changes in water quality/quantity. However, by assessing all data since 2010, the general trends can be detected and these were discussed in each section.

8.2.2 Copperfield Creek

Surface water quality monitoring at PCPWD shows that an increase in pH is occurring with a non-significant upward trend and the resulting decrease in bioavailable metals since 2010. However, cadmium and zinc concentrations downstream at PCCK06 do exceed the 2013/14 ISSTV. This is a reduction from the previous year’s results which showed copper and nickel also exceeding the ISSTVs. Concentrations of zinc at PCCK06 are sufficient to cause adverse environmental harm to aquatic organisms.


The water chemistry results show that PCCK06 and PCCK06B are within the mixing zone of the PCPWD discharge as the PCCK06 site is only 100 m downstream of the confluence of the PCPWD spillway tributary and Copperfield Creek. Even though Copperfield Creek provides dilution during discharge, it is insufficient at PCCK06 and PCCK06B to allow these sites to meet the ISSTV for zinc. However, all other ISSTVs are met at PCCK06B, therefore PCCK06B may be a better location for the WDL compliance point to meet the 2014/15 SSTVs. However, access issues preclude this scenario. If a controlled discharge regime is applied to the PCPWD discharge, the volume of discharge may be adjusted to meet the SSTVs at PCCK06.

8.2.3 Pine Creek

Surface water quality monitoring at PCCK04 showed a slight decrease in pH and concentrations of zinc at PCCK03 higher that the ISSTV on all sampling occasions during the 2013/14 wet season. All other analytes were below the ISSTV at PCCK03. Care must be taken when interpreting PCCK03 data as the rail may influence water quality at the site.

8.3 Site Specific Trigger Values

Sufficient data was available of appropriate quality to calculate site specific trigger values for Pine Creek and Copperfield Creek for the 2014/45 wet season. The high background levels of iron, aluminium, turbidity and the low background of dissolved oxygen have all been taken into account in the calculation of the SSTVs. Hardness correction factors were applied to cadmium, copper, lead, nickel and zinc at PCCK03 using the 80th percentile of hardness at that site.

From the water quality data, the monitoring sites PCCK03 and PCCK06 are within the mixing zone of their respective discharges as the SSTVs are routinely exceeded. SSTVs are applied to the edge of the mixing zone where background concentrations are expected to be met. Active controlled management of discharges may be required to calculate the required volume to be discharged (particularly from PCPWD) to meet the dilution factor calculated in Section 6 and the mixing zone can then be accurately determined.

8.4 Sediment Quality

The sediment analysis results demonstrate that there is an increase in bioavailable zinc concentrations downstream of discharges in both Copperfield Creek and Pine Creek. The source of zinc causing the observed exceedances however is not able to be solely linked to the mine discharges as there is evidence to suggest additional sources of metal contamination between the discharge locations and downstream sites.

The results indicate that there is likely to be a toxic impact within the immediate vicinity of Copperfield Creek Discharge (PCPWD), with a lesser impact at Pine Creek (PCCK04), however the observed effects are likely to be restricted to the immediate discharge zone. These conclusions are supported by the results of the ecotoxicity tests discussed in Section 6.

8.5 Biological Monitoring

Results of the biological monitoring studies conducted from 2010 to 2014 show that there were no significant differences in any of the univariate macroinvertebrate indices between Control site and Impact site sample groups. There was, however, significant year to year variation in Abundance, Taxa Richness and PET Richness. The latter related mainly to the very low diversity and abundance of macroinvertebrate fauna collected in 2012 and the high abundance and diversity of macroinvertebrate fauna collected in 2013.

Results of multivariate analysis showed that there was a significant difference in community composition between Control site and Impact site samples as well as between years. A difference in community composition between treatment groups was attributable largely to differences in relative abundance of taxa with low to moderate pollution sensitivity. Further, there was no consistent pattern of higher abundances of these taxa in Impact site samples, as one might expect under a pollution impact scenario. Hence, those differences probably relate to factors other than treated mine affected water release.


Overall there is no evidence to suggest that the PCPA has had any negative impact on the macroinvertebrate community in Pine Creek and Copperfield Creek. This result might be at least partly attributable to the low to moderate levels of pollution sensitivity associated with the macroinvertebrate taxa present within the PCPA study area.

It should be pointed out that the data analyses performed on the PCPA data have limited statistical power due to the fact that there has not been any within-site sampling replication. Hence there is a real risk of both Type I errors (rejecting the null hypothesis when it is true) and Type II errors (accepting the null hypothesis when it is false). Hence, these results should be interpreted with caution. Given the level of between year and within-treatment variability observed in this study, this issue should be addressed through changes to the study design in future programs.

8.6 Ecotoxicology

The screening tests showed that the results are influenced by the water flows in the creeks and it is difficult to compare the results from the same sites from different years due to this influence. However, screening tests are useful for determining the edge of a mixing zone, however, this is also dependent on discharge volume and creek flow and can be measured more easily by water chemistry.

Zinc is present in concentrations that have the potential to cause toxicity in PCCK03, PCCK06 and PCCK06B. Zinc can be measured and the results used to determine the influence of the discharges from PCCK04 and the PCPWD on the receiving water in place of using screening bioassays.

Both the PCCK04 and PCPWD water samples show that dilution is required to ameliorate toxicity, particularly for the cladoceran, the most sensitive species. Zinc is the main contaminant of concern in both samples, however, PCPWD also contains nickel, copper, manganese and cadmium in concentrations that have the potential to cause toxicity. It is unlikely that aluminium has the potential to have a major contribution to toxicity.

The PCPWD dilution factor calculated by ERISS (2010) of 1:1,000 shows the dilution required for a worst case water quality scenario. The 2013 PCPWD dilution factor of 1:238 shows the dilution for the best case water quality scenario.

The current management of PCPWD discharge does not allow the active utilisation of the SSD calculated for downstream environmental protection. To obtain the maximum value of the SSD results and to manage discharge from PCPWD in a more environmentally relevant manner a method that allows greater control and the ability to measure the discharge is required. The same comment applies to PCCK04, without a responsive management control of discharge volumes the results of the toxicity tests are not able to be utilised to their greatest potential.

8.7 Risk Assessment

This risk assessment took a semi-quantitative and conservative approach to assess the risks to the beneficial use and values for the area of Pine Creek and Copperfield Creek in the vicinity of surface water monitoring sites PCCK04 and PCPWD. The risk assessment identified:




However, water quality at the compliance points PCCK03 and PCCK06 suggests the risks posed by these parameters may not be as high as the risk assessment suggests. Furthermore, there is evidence of dilution of these parameters further downstream in both Pine Creek and Copperfield Creek. It is also apparent the water quality in both study reaches is influenced by elevated iron, which is high in upstream sites.

8.8 Recommended variations to WDL 166

The following variations to WDL 166-02 are recommended to be implemented into WDL166-03:

Reporting requirements changed to annual at the end of the wet season to capture WQ data for the WMP management of water on site to fit with site operational requirements.

Retain the SSTVs to apply to PCCK06 and PCCK03.

Remove chromium and selenium from the monitoring program.


9. Recommendations Table 9-1 Recommendations Table


Surface Water

2.1 The Copperfield Creek 2014/15 compliance point retained at PCCK06

2.2 A mixing zone study to confirm the location of the Copperfield Creek compliance point.



2.5 Investigate a monitoring site downstream from PCCK03.

2.6 Investigate the source of the decrease in pH at PCCK04 if the decrease continues.

Site Specific Trigger Values

3.1 Update the SSTVs on an annual basis.

3.2 Determine the mixing zones for Pine Creek and Copperfield Creek to determine appropriate monitoring locations to meet the SSTVs.

3.3 Controlled discharges to enable SSTVs to be met at downstream monitoring sites.

Sediment


4.2 Consideration should be given to removing the requirement for total metals analysis in sediment analysis. The total metals analysis does not add significant value to environmental impact interpretation process, as the ANZECC ISQGs are based on bioavailable metals.


Biological Monitoring

5.1 Investigate a revised study design to increase within site replication and statistical power.



5.2 Sample processing methodology to be maintained.

5.3 Retain SIGNAL data and review its use after the next two sampling rounds.

Ecotoxicology Program

6.1 Remove all screening bioassays from the program.

6.2 Conduct the direct toxicity assessment on PCCK04 and PCPWD on a three yearly basis. As water quality monitoring is taken on a routine basis, the water quality results will provide information on the potential toxicity of the discharge water which can be confirmed with the three yearly ecotox program.



6.5 Investigate using water quality data and ecotoxicology results to date to determine a process where ecotoxicity can be predicted based on water quality results.

Recommended Variations to WDL

Item 28

WDL Reporting requirements should be changed to annual to capture annual water quality at the end of the wet season to allow for management actions of water on site to be incorporated into the annual Water Management Plan review.

Reporting period recommended: July – June

Item 16 Retain the SSTVs to apply to PCCK06 and PCCK03.

Appendix 1 Remove chromium and selenium from the monitoring program.


10. References ANZECC & ARMCANZ (2000) Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand. National water quality management strategy, Australian and New Zealand guidelines for fresh and marine water quality. ANZECC and ARMCANZ, Canberra, Australia.

Campbell E., Palmer M.J., Shao Q., Warne M.StJ. and Wilson D. 2000. BurrliOZ: A computer program for calculating toxicant trigger values for the ANZECC and ARMCANZ water quality guidelines. Perth, Western Australia.

Cherry D.S., Currie R.J., Soucek D.J., Latimer H.A. and Trent G.C. 2001 An integrative assessment of a watershed impacted by abandoned mined land discharges. Environmental Pollution, 111: 377-388.

Chessman, B. 1995 Rapid Assessment of rivers using macroinvertebrates: a procedure based on habitat-specific sampling, family level identification and a biotic index. Australian Journal of Ecology 20:122-129.

Clements, WH., 1999. Metal tolerance and predator-prey interactions in benthic macroinvertebrate stream communities. Ecological Applications 9: 1073-1084.

Courtney LA, Clements WH 2002 Assessing the influence of water and substratum quality on benthic macroinvertebrate communities in a metal-polluted stream: an experimental approach. Freshwater biology, 47: 1766-1778.

Dallas, H., and Day, J. 2004. The effect of water quality variables on aquatic ecosystems: a review. Retrieved from http://library.wur.nl/WebQuery/clc/1928741

Elphick J.R., Davies M., Gilron G., Canaria E.C., Lo B. and Bailey H.C. 2011. An aquatic toxicological evaluation of sulfate: The case for considering hardness as a modifying factor in setting water quality guidelines. Environmental Toxicology and Chemistry. 30(1):247-253

ERISS 2010. Ecotoxicological assessments of discharge waters from Cosmo Howley, Pine Creek, Tom’s Gully and Brocks Creek Project Areas. Report for Crocodile Gold Australia Operations. Environmental Research Institute of the Supervising Scientist. Department of the Environment, Water, Heritage and the Arts. Darwin NT.

Gerhardt A., Janssens de Bisthoven L. and Soares A.M.V.M. 2004 Macroinvertebrate response to acid mine drainage: community metrics and on-line behavioural toxicity bioassay. Environmental Pollution, 130: 263-274.

Gray N.F. 1998 Acid mine drainage composition and the implications for its impact on lotic systems. Water Research, 32 (7): 2122-2134.

Hoehn R.C. and Sizemore D.R. 1977 Acid mine drainage (AMD) and its impact on a small Virginia stream. Water Res. Bull. v. 13, pp. 153-160.

Jarvis A.P. and Younger P.L. 1997 Dominating chemical factors in mine water induced impoverishment of the invertebrate fauna of two streams in the Durham coalfield, UK. Chemistry and Ecology, 13: 249-270.

Kelly M. 1988 Mining and the freshwater environment. London: Elsevier Applied Science.

Lamche, G. 2007. The Darwin-Daly Regional AUSRIVAS Models –Northern Territory: User Manual. Aquatic Health Unit –Department of Natural Resources, Environment and the Arts. Report 06/2007D.

Marchant, R. (989. A sub-sampler for samples of benthic invertebrates. Bull. Aust. Soc. Limnol. 2 49-52.


Mason C.F. 2002 Biology of freshwater pollution. Harlow: Pearsons Education Ltd.

MDBC 2004 Macroinvertebrate Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 07/04. Canberra, Australia. ISBN 1 876830 74 3.

Nelson M.S. and Roline R.A. 1996 Recovery of a stream macroinvertebrate community from mine drainage disturbance. Hydrobiologia, 339: 73-84.

Peters, G., Doeg, T. and Heron, S. 2009. Aquatic Value Identification and Risk Assessment (AVIRA) Risk Assessment Process. Report for the Department of Sustainability and Environment. April 2009.

Ravengai S 2005 Impact of Iron Duke Pyrite Mine on water chemistry and aquatic life Mazowe Valley, Zimbabwe. Water SA, 3 (2): 219-228.

Ryan, P. A. 1991. Environmental effects of sediment on New Zealand streams: A review. New Zealand Journal of Marine and Freshwater Research 25 (2), pp. 206-221.

SKM. 2012 Pine Creek Project Area 2010-2012 Environmental Monitoring Report. Prepared for Crocodile Gold Australia Operation, September 2012. 148 pp.

Smith, R., Jeffree, R., John, J and Clayton, P. 2004. Review of methods for water quality assessment of temporary stream and lake systems. Report for ACMER.

Stauber, J.L., Tsai, J., Vaughan, G.T., Peterson, S.M. and Brockbank, C.I. 1994. Algae as indicators of toxicity of the effluent from bleached eucalypt kraft paper mills. National Pulp Mills Research Program Technical Report No. 3 Canberra: CSIRO, 146 pp.

Tiller, D. and Newall, P. 2009 Interpreting River Health Data Waterwatch Victoria, EPA, Victoria

Walsh, C.J., Leonard, A.W., Ladson, A.R. and Fletcher, T.D., 2004 Urban stormwater and the ecology of streams. Cooperative Research Centre for Freshwater Ecology and Cooperative Research Centre for Catchment Hydrology, Canberra.

GHD | Report for Crocodile Gold - Pine Creek Project Area, 43/22192

Appendices


Appendix A – WDL 166-02

00O^^'Q

.

.

.

Licence Details

Licence Number:

Commencement Date:

Expiry Date

WASTE DISCHARGE LICENCE(Pursuantto section 74 of the Water AGO

Licensee Details

Legal Entity Name:ACN:

Registered BusinessAddress:

WDL, 66.02December 2012

31 August 2014

Postal Address:

Contact Person:

Position Title:

Contact Details:

Crocodile Gold Australian Operations Pty Ltd136 525 990

39 Vereker Street, Humpty Doo, N. T 0836PO Box769HUMPTYDOONT 0836

Peter Crooks

General Manager- NT Operations

Location of Premises

Name:

b/h: (08) 89395000mobile: 04,2768633

email: PCrooks@crocgold. coinfax: (08) 89395099

Address:

Telephone Numbers:

24 hour emergency responseContact Person:

Telephone Numbers:

Pine Creek Mine SiteMine Lease North 13 and 1130

Old Stuart HighwayPINE CREEKNT 0847

b/h: 08 8939500o

mobile: 04/2768633

Licensed Activity

b/h: 08 8978/555

mobile: 04,2768633

Discharge of wastewaterfrom the Pine Creek Mine Site to CopperfieldCreek and Pine Creek subject to this Licence.

EN2010/0258/0027

Crocodile Gold Emergency Contact Line

Page I of, 7

TABLE OF CONTENTS

Licence Details

TABLE OF CONTENTS

Definitions of Terms

Responsibilities of Licensee

Duration of Licence

Amendment, Modification or Revocation of Licence (section 93 of the Water Act. )

Public Register

Supporting Guidelines and Documents

Environment Protection Objectives (Part 4 of the WMPCA) and Beneficial Use Declaration (section 73 ofthe Water Act)

Environmental Interests

LICENCE CONDITIONS

ADMINISTRATIVE

OPERATIONAL

DISCHARGES AND EMISSIONS

MONITORING

RECORDING AND REPORTING

DEFINITIONS

APPENDIX I - SURFACE WATER MONITORING PROGRAM

APPENDIX 3- BIOLOGICAL MONITORING PROGRAM

APPENDIX4- ANNUAL COMPLIANCEAND AUDIT REPORT

WASTE DISCHARGE LICENCE (WDL 166-02)

2

3

3

3

4

4

4

4

4

5

EN20i0/0258/0027

5

5

6

6

7

9

10

16

17

Page 2 of 17

.

.

Definitions of Terms

. A section on the definition of terms used in this Licence can be found at the end of this Licence

. Terms used in the waste discharge licence which are defined in the Water Act(the Act) have themeaning given in that Act unless specifically indicated otherwise

Responsibilities of Licensee

. It is an offence under the Water Act, ifthe holder of a waste discharge licence contravenes orfails tocomply with the conditions of a waste discharge licence

. In addition to the conditions set out in this Licence, general responsibilities of Licensees are set outin the Waste Management and Pollution ControlAct(WMPCA) and associated Regulations and theWater Act

. Licensees must comply at alltimes with the requirements of these Acts and all other applicable laws

. not cause environmental harm either directly or indirectly

. waste to come into contact with water; or

. water to be polluted.

. Without limiting the conditions of this Licence, in conducting the Activity, the Licensee must do allthings reasonable and practicable to

. prevent or minimise the likelihood of pollution occurring as a result of, or in connection with,

the Activity;

. prevent or minimise the likelihood of environmental harm occurring as a result of, or in

connection with, the Activity;

. effectiveIy respond to pollution and the risk of pollution occurring as a result of, or in

connection with, the Activity;

. effectiveIy respond to environmental harm and the risk of environmental harm occurring as a

result of or in connection with the Activity; and

. asfaraspracticable

. avoid and reduce waste produced as a result of, or in connection with the Activity;

. increase the re-use and recycling of waste;

. effectiveIy managewaste disposal; and

. apply the principles of ecologicalIysustainable development

Duration of Licence

. This Licence will remain in force untilits expiry date, unless it is surrendered by the Licensee or untilit is suspended or revoked by the Controller


EN201010258/0027 Page 3 of 15

Amendment, Modification or Revocation of Licence (section 93 of the Water Act

The Controller of Water Resources may, by notice:

. amend ormodifythe terms and conditions of a licence;

. revokealicence;or

WASTE DISCHARGE LICENCE(WDL ,66 02

as set outin section 93 of the Water Act.

.

Public Register

A copy of this Licence will be placed on a register in accordance with section 95 of the Water Act.

The register is publicly available for viewing on the Department's website.

A copy of the Annual Audit and Compliance Report will also be placed on the register.

Supporting Guidelines and Documents

This Licence has been developed based on the information provided by the Licensee in the followingdocumentation:

. CGAO Pine Creek Waste Discharge Licence Application, Cover Letter and supporting documentationdated 3 October 2012;

suspend a licence

. Waste Discharge Licence 166-1.

Environment Protection Objectives (Part 4 of the WMPCA) and Beneficial Use Declaration(section 73 of the Water Act)

An Environment Protection Objective (EPO) is a statutory instrument to establish principles on which:

a) environmental quality is to be maintained, enhanced, managed or protected;

by pollution, or environmental harm resulting from pollution, is to be assessed, prevented, reduced,controlled, rectified or cleaned up; and

c) effective water management is to be implemented or evaluated.

In accordance with section 18 of the Act a beneficial use, quality standard, criteria or objective declared undersection 73 of the Water Act and in force is an environment protection objective forthe purposes of the WMPCA.

The following EPOs and BUDS, as amended from time to time, are relevant to this Licence:

Declaration of Beneficial Uses and Objectives, Copperlield Creek, Northern Territory Gazette NO G2311/6/1 997.

Environmental Interests

This section highlights sensitivity of the surrounding land use and environment associated with the location ofthe approved activity that represents an interest to the Northern Territory Government and the community.

. The Pine Creek bioregion in the document Rangelands 2008 -Taking the Pulse under the AUStrafianGovernments Rangelands. A bioregional description of the Pine Creek area is available at:

htt ://WWW. environment. ovau/landl ublicationslacris/ ubs/biore 10n Ine-creek. of

EN2010/0258/0027 Page 4 of 15

.

.


LICENCE CONDITIONS

ADMINISTRATIVE

The Licensee must notify the Administering Agency within 24 hours ifthere are changes to the details ofthe 24-hour emergency contact as provided on page one of this Licence

The Licensee must notify the Administering Agency within 14 days ifthere are changes to the Licenseedetails shown on page one of this Licence

The Licensee must notify the Administering Agency within 14 days after ceasing to conductthe activity towhich this Licence relates

The Licensee must notify the Administering Agency prior to making any operational change that willcause, or is likely to cause, an increase in the potential for environmental harm, environmental nuisance,material environmental harm or serious environmental harm

The Licensee must cause a copy of this Licence to be available at alitimes

on the Licensee's Australian website; and5. I

at the Location5.2

Where this Licence requires the provision of any notice, document or other correspondence to theAdministering Agency, the relevant contact is

Environment Operations Unit

Physical Address: Level 2 Darwin Plaza, 41 Smith Street Mall, Darwin NT 0800

Postal Address: GPO Box 3675, Darwin NT 0831

Email: environmentops. nretas@nt. gov. au

All notices, documents or other correspondence required to be provided pursuant to this Licence must beprovided in both hard and electronic form unless otherwise specified as a condition of this Licence

OPERATIONAL

The Licensee must, without limiting any other condition of this Licence in conducting the Activity do allthings reasonable and practicable to ensure the Activity does not adversely affectthe Declared BeneficialUses and objective as declared from time to time, including those applying to:

. CopperfieldCreek

The Licensee must maintain and implement a communication plan which includes a strategy forcommunicating with members of the public who are likely to have a genuine interest in or be affected bythe Activity

The Licensee must maintain a log of each complaint, made in relation to the Activity, to any personsinvolved in the Activity. The log must include details of the following:

. the date and time of the complaint;

. the contact details of the complainantif known, or where no details are provided a note to thateffect;

. the natureofthecomplaint;

. ' the nature of events giving rise to the complaint;

. prevailing weather conditions at the time of the complaint;

2.

3

4

5

6

7

8

9

10

EN2010/0258/0027 Page 5 of 15


. the action taken in relation to the complaint, including anyfollow-up contact with thecomplainant; and

. if no action was taken, why no action was taken

DISCHARGES AND EMISSIONS

This Licence authorises wastewaterto be discharged from the Authorised Discharge Point(s) identified inTable I

11

Table I

Authorised Discharge Point

PCPWD

PCCK04

12 Waste water(s) discharged from the authorised discharge points in Table I must not:

. contain any visible matter, floating oil and grease or petroleum hydrocarbon sheen or scum, orlitter or other objectionable matter;

. cause or generate odours which would adversely affectthe use of surrounding waters;

. causealgalblooms;

. cause visible change in the behaviour offish or other aquatic organisms;

. cause mortality offish or other aquatic organisms; or

. causeadverseimpactson plants

MONITORING

The licensee must for all terrestrial sampling points required by this Licence

install, maintain and provide appropriate identification signage so that they are easily13.1

Identifiable at all times; and

13.2. maintain safe access and egress, as is reasonably practicable

For each sample required to be collected by this Licence the following information must be recorded andretained:

. the date(s) on which the sample was taken;

. the time(s) at which the sample was collected;

. the point(s) at which the sample was taken;

. the name of the person who collected the sample;

. the chain of custodyforms relating to the sample(s);

. the field measurements and/or analytical results forthe sample; and

. laboratoryQAIQCdocumentation

Description

Pine Creek Process WaterDarn at the Weir Boards

(MLN 13 Influences)

Pine Creek MLN 13 Eastern

Tenement Boundary.

Downstream of Sth Ghandi's

(MLN 1/30) and EnterprisePit (MLN 13)

I 3.

Location

Latitude: -I 3.847 o

Longitude: 131.835'

Latitude: -I 3.81 9 o

Longitude: 131.827 o

14

EN2010/0258/0027 Page 6 of 15


Surface water monitoring must be conducted in accordance with Appendix I

The Licensee must, at Monitoring Points PCCK06 and PCCK03 apply the interim site specific triggervalues as listed in Table 4-5 of the Crocodile Gold Australia Operatibn PIhe Creek Project Area 2017-2012 Monitoring Report and Appendix I of this Licence.

Sediment monitoring must be conducted in accordance with Appendix 2

Biological monitoring must be conducted in accordance with Appendix 3 and the Biological MonitoringEnvironment Management plan for PIhe Creek ProjectArea 2072 dated 4 March 2072

ECotoxicological monitoring must be conducted in accordance with the EGOtoxic0/o910a/ Monitoring Planfor PIhe Creek ProjectArea 2072 document dated 6 March 2072 ("the ECotox Plan") or revisionsapproved in accordance with condition 20 of this Licence.

The Licensee must submit an amendment to the ECotox Plan dated 6 March 2012 by 31 January 20.3 toinclude an assessment of wastewaterfrom the Authorised Discharge Points, PCPWD and PCCK04. Theproposal to amend must

include, instream monitoring points upstream and downstream of the Authorised Discharge20.1

Point PCCK04;

20.2. be approved by the Administering Agency noting that the Administering Agency may requirethe Licensee to revise, amend and/or resubmitthe proposed plan; and

20.3. be implemented within 10 Business Days of receiving written approval of the plan from theAdministering Agency

The Licensee must cause a copy of the ECotox Plan to be available on the Licensee's Australian website

RECORDING AND REPORTING

All records required to be kept by this Licence must be in a legible format

The Licensee must keep records of all non-compliances with this Licence

The Licensee must as soon as practicable and in any case within 24 hours notify the AdministeringAgency of non-compliances with this Licence

The Licensee must immediately and in any case within 24 hours notify the Administering Agency of anypotential or actual environmental harm or pollution by contacting the Pollution Hotline on telephonenumber 1800 064 567 and emailing environmentops. nretas@nt. gov. au

The Licensee must immediately and in any case within 24 hours notify the Administering Agency in writingwhen the qualitative parameters in condition 12, or the site specific trigger values in Appendix I of thisLicence are exceeded on three or more consecutive sampling and/or monitoring occasions. The writtennotification must include

26.1 an assessment of risk posed by the discharge; and

26.2 details of the action undertaken to mitigate the risk

The Licensee must comply with the requirements of section 14 of the Waste Management and PollutionControlAct

The Licensee must provide to the Administering Agency a Monitoring Report, in accordance with thefollowing schedule

45

16

17

18.

19

20

21

22

23

24

25

26

27

28

Reporting Period

December 2012 - October 2013

November 2013 - July 2014

EN2010/0258/0027

Report Submission at the end of:

November 2013

August 2014

Page 7 of 15

29 The Monitoring Report must

be prepared in accordance with the requirements for a Monitoring Report identified on pages29.1

12-24 of the document: Guidelines for Report^^g in Environmental Issues available fromhtt ://WWW. nretas nt. ovaul data/assets/ of file/0009/14031/consultants re onin environinentalissues df, and

include a trend analysis and interpretation of monitoring results (field data and analyticalparameters) required as a condition of this Licence

30. The Licensee must complete the attached Annual Audit and Compliance Report (AACR), Appendix 5 andprovide to the Administering Agency a minimum of 20 Business Days prior to the anniversary of thecommencement date of this Licence, for each year of this Licence

The Licensee must provide to the Administering Agency a minimum of 20 Business Days prior to theexpiry date of this Licence a Licence Report

The Licence Report must include

results of the ecotoxicological monitoring program together with a detailed interpretation of31.1

the results; and

revised site specific trigger values including all supporting documentation that relates to thederivation of the trigger values

END OF LICENCE CONDITIONS


29.2

31.2

This Licence is not valid unless signed below

William John Freeland

Delegate of the Controller of Water Resources

Dated the I\__/ .a, ,^/ 2012

EN201010258/0027 Page 8 of 15

DEFINITIONS

Allterms in the Licence which are defined in the Water Act have the meaning given in that Act unlessotherwise or further defined in this section

'Act'

'Activity'

WASTE DISCHARGE LICENCE(WDL 166 02

'Administering Agency'

'Business Day'

'Beneficial Use'

'Commencement Date'

means the Northern Territory of Australia Water Act

means the activity licensed under this Licence described as Licensedactivity on page I of this Licence

The definition does notin any way limitthe meaning of the term given in theAct

means the Department of Lands, Planning and the Environment

means a day not Saturday, Sunday or a public holiday in Darwin, NorthernTerritory

means the uses of water specified in subsection (3) of the Water Act

Means the date on which this Licence is signed by the Controller of Wateror his or her delegate, as indicated on page one of this Licence

Means a plan to deal with emergencies that may, or have the potential toadversely impact on the environment including but notlimited to fire, spillsand accidents

Means the date on which this Licence expires, as indicated on page one ofthis Licence

Has the meaning described in section 14 of the Waste Management andPollutibn ControlAct

Is the Location of Premises as described on page I of this Licence

Means any failure by the Licensee to comply, in whole or in part, with anycondition of this Licence regardless of the duration of the non-compliance

any written information as requested as a condition of this Licence. Anylogs, registers or other documents

means any site listed at

htt Iwww. nretas nt ovau/environment-rotection/conservation/data resources

'emergency response plan'

'Expiry Date'

'Incident'

'Location'

'non-compliance'

'records'

'Sites of Conservation

Significance'

'wet season'

'WMPC Regulations'

'WMPCA'

the period I October 2012 to 30 May 2013 and the period from I October2013 to 30 May 2014

means the Waste Management and Po"ution Control(Admim^tratibn)Regulations of the Northern Territory

means the Waste Management and Pollution ControlActofthe NorthernTerritory

EN2010/0258/0027 Page 9 of 15

APPENDIX I-SURFACE WATER MONITORING PROGRAM


Site Code

Parameter

SURFACE WATER MONITORING LOCATIONS

Longitude

PINE CREEK

Field Measurements (in situ)

Flow

coo:<ooo.

Water Level

Latitude

Abbr

pH

*-

o><ooD. .

o

cococo,-

co^

Electrical

Conductivity

CNo><ooD_

<.o><ooD_

o

o,-.

co,.

co,.

Units

Dissolved Oxygen

.^

coco,-

co

o

.a'*-

co

co^

COPPERFIELD CREEK

Temperature

*

^!:

o

I\Nco,-

co

o

I~,-

co

co*-.

,-

coco

kLlday

Dissolved Metals (Filtered 0451, in)

pH

CDo><ooQ.

.

co,-

co

co

,-

Aluminium

EC

in

.

^::D.oD_

pH units

Arsenic

o

co,-

co

co,-

NA

o

cococo^

co

Do

CD<0o:=<oo_

Cadmium

PSIcm

,-

NA

o

<.coco,-.

co

6.0 - 7.5

Chromium

^

T

v,saturation

Co

><ooD_

W

,-

Cobalt

o

N<0co

co

o

I\Nco*-

co

W

20-250

,-

^

NA

N::<ooD. .

Copper

A1

*

W

'C

^:

.

oNco,-

co

.

I~.a'co

co,-

NA

,-

35.120

W

coco

As

Iron

W

W

o

coI\co

co,-

o

cooco,-

co,-.

,-

W

NA

,-

Cd

Lead

NA

NA

W

W

W

.

C\I<0co

co

Cr

NA

W

W

Co

W

o

cococo

co,-,-

508

NA

W

EN20101025810027

6.0.7.5

W

Cu

W

140

W

W

pg/L

W

Fe

20- 250

M

W

0.8

W

W

W

Pb

W

M

40

NA

45-120

M

W

W

M

W

NA

NA

M

NA

M

M

NA

W

5

W

M

W

NA

M

M

NA

M

NA

M

M

W

W

M

W

W

NA

590

M

9.4

M

M

M

W

Q

W

140

W

M

M

M

M

W

M

0.8

Q

W

W

M

M

M

W

M

40

M

W

M

M

Q

W

NA

M

M

M

M

W

Q

M

2.5

M

M

M

W

NA

M

M

M

W

Q

9.4

M

M

M

W

Q

M

M

M

W

Q

M

M

M

Q

M

Page 10 of 15

M

M

Q

M

M

Q

M

Q

Q

,

Manganese


Nickel

Selenium

Zinc

Environmental Indicators

Mn

Turbidity

Site Code

Total SuspendedSolids

Ni

Se

SURFACE WATER MONITORING LOCATIONS

Total Dissolved

Solids

PINE CREEK

Zn

Hardness

3600

coo:<ooD_

NTU

Carbonate

17

,-

o><ooo.

Bicarbonate

TSS

M

34

No><ooD_

Alkalinity

NTU

M

31

TDS

M

.,.o><ooD_

Calcium

M

CaCO3

M

M

Magnesium

COPPERFIELD CREEK

2-15

M

M

M

Co3

M

Potassium

NA

HC03

M

M

M

<0o><ooD_

Sodium

3600

M

CaCO3

M

M

Chloride

NA

.

^::D.oo.

17

M

M

M

Ca

Sulphate

W

NA

34

CDCoo><oD_

M

M

Mg

KEY

NR - Not Required

W-Weekly

M - Monthly

M

W

inglL

NA

M

95

co

:<ooD_

M

W

M

^

K

M

NA

M

M

M

Na

W

M

,-

M

NA

NA

N>,:ooD_

M

M

M

M

M

Cl

M

NA

M

NA

M

M

M

M

So4

M

W

Q

M

NA

M

M

M

M

M

NA

Q

M

W

NA

M

M

M

M

M

Q

M

NA

NA

M

M

M

W

M

M

Q

M

NA

13

M

M

EN2010/0258/0027

M

M

M

W

M

M

NA

NA

M

M

M

W

Q - Quarterly

IsSTV* - Interim Site Specific Trigger Value

M

M

M

NA

M

M

M

M

M

W

M

NA

M

M

M

M

M

M

M

W

NA

M

M

M

M

M

M

M

W

NA

M

M

M

M

M

W

M

NA

M

M

M

M

W

M

M

13

M

M

W

M

NA

M

M

M

W

M

M

M

M

W

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

Page 11 of 15

APPENDIX2- SEDIMENT MONITORING PROGRAM


Parameter

Site Code

Copper

Abbr.

Zinc

PINE CREEK

,-

Longitude

o><ooQ.

Lead

Cu

units

No><ooo_

Nickel

SAMPLE LOCATIONS

Fe

Q

o,-

co,-

co

Arsenic

TriggerValue

coo><ooD_

Latitude

Pb

Cadmium

o,-

coco,-

co,-,-

.d'o><ooD_

Ni

Chromium

o

I\t-

co

co

cocoC

coD^ ,-:O un>co^ coto p

OF-coco OE ILl

co Zco <

EL-

co^,

=

Analysis type

o

cococo,-

co,-.

As

COPPERFIELD CREEK

NOTES:

A- Annual: Prior to cessation of creek flow at the end of the wet season.

ing/kg

.

;=a.

Q

co,-

co

co,-,-

Cd

o

I~Nco,-

co,-

coo><ooD_

o

<.*-

co

co,-

Cr

Q

<.coco^

co*-

CDCoo><ooo_

co^ o DC coTto

~ toto O >O E Co

oI- ,- .-

P

A

oco*-

co

co,-

.

cococot-

co

A

co

><ooo_

A

,-

o

I\.,.co

co^

o

I\61co,-

co

A

*-

A

A

,-

o

C\ICoco

co

N><ooa.

A

.

oC\Ico,-

co,-

A

,-

A

A

A

.

coI\co

co*..

A

o

cooco,-

co,-

A

A

A

A

A

o

C\I<0co

co,-

A

A

A

A

A

A

A

,-

o

coaco

co,-

A

A

A

A

A

A

A

A

A

A

A

A

A

A

EN20i0/0258/0027

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

Page 12 of 15

,

,

APPENDIX 3- BIOLOGICAL MONITORING PROGRAM

SITECODE

PCCKOl


PCCK02

Pine Creek upstream of Green ValleyRoad (control)

PCCK03

DESCRIPTION

Pine Creek Main Terrace Crossing (D/Scompliance)

PCCK04

Ikm downstream of Pine Creek projectarea at railway crossing location

Pine Creek MLN 13 Eastern Tenement

Boundary

Downstream of Sth Ghandi's (MLN 1130)and Enterprise Pit(MLN 13)

PCCK16Copperfield Creek upstream of any minesite discharge at the Jindare/UmbrawarraRoad Crossing (control)

PCCK06

LONGITUDE

PCCK06B

loom downstream of the confluence of

Copperfield Creek with the process waterdarn spillway tributary (compliance)

_, 3 8170

PCCK2i

Key

-I 3.81 80

LATITUDE

2km downstream of PCCK06

*

Copperlield Creek - 20km downstream ofdischarge

_, 3 8140

Prior to cessation of creek flows at the end of the wet season

131.810'

FREQUENCY

131.83jo

'38/90

131.839'

Annual*

_13.862o

Annual*

131.827o

_13,862o

Annual*

131.820'

_13,878o

Annual*

_, 3.994'

131 8330

131 8270

Annual*

EN2010/0258/0027

13,903'

Annual*

Annual*

Annual*

Page 13 of 15

APPENDIX4-SITE MAPWITH SURFACEWA ER MONITOR NG POINTS

WASTE DISCHARGE LICENCE(WDL 166 02

804000

Q

8

a

^,~

...-~~-/,

\

\

I

\

e,

806000

^Zl

.

^

LA

\\

\

\

,\

\

\

*<^!C,\.

\

808000

^I

\

.

^.

^::,

* PCCK03

q

^.

MLN13

e

.^

~.

1301^a

~

a

^

PCPWD

PCCK16

I

^<:?IF^.*

13RDCUDILGOLD

EN2010/0258/0027

muono

Q

in

1,611

PCCK06

RUS'rRALin OPERATioris a;

2IQ or netres

,

^PCCKO D

^

806000

Pine Creek

Project Area

e

Legend

8

^,~

^ MonitoringDischarge

Mirror Watercourse

^ MainRoad

Mirror Road

I^. CGAo_ML_Granted

^.

808000

e

Page 14 of 15


Appendix B – Water Quality Data

PINE CREEK CATCHMENT

Table 1: PCCK01 Summary Table

PCCK02 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15

Lower trigger 6 20 35 2

Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1

Number of Results 123 124 62 63 54 54 54 54 46 54 54 54 54 54 24 54 56 56 56 56 59 59 59 63 62 55 47 23

Minimum Concentration 5.31 18.83 17.30 14.30 15.00 0.50 0.01 0.09 0.30 0.50 90.00 0.50 0.50 0.26 0.10 0.50 0.25 0.90 0.25 0.25 7.00 0.05 7.00 0.25 0.50 1.50 2.50 6.30

Median Concentration 6.56 39.90 79.60 26.00 96.00 1.00 0.05 0.50 0.50 0.50 470 0.50 16.50 0.50 0.50 2.00 0.50 1.70 3.70 0.70 15.00 0.50 15.00 0.50 3.00 4.00 2.50 20.00

Maximum Concentration 8.33 213 162.2 76.70 2600 7.00 0.60 2.00 2.00 11.00 2500 4.00 120 0.50 2.00 170 2.80 3.60 6.80 1.60 32.00 2.50 32.00 6.00 7.00 10.00 51.00 63.00

20th%ile 6.16 32.68 56.56 22.10 28.4 0.50 0.05 0.50 0.50 0.50 300 0.50 7.00 0.50 0.50 0.50 0.25 1.10 2.60 0.50 11.00 0.50 11.00 0.50 2.00 3.00 2.50 9.28

80th%ile 6.93 58.46 108.7 40.82 362 2.00 0.05 0.50 0.50 2.40 774 0.50 24.40 0.50 0.50 10.20 0.80 2.30 4.60 1.00 20.40 2.50 20.40 0.50 4.00 6.00 9.00 38.00


PCCK02 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

Tota

l Sus

pend

ed S

olid

s @

103

-10

5o C (m

g/L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1



Median Concentration 6.32 195.15 67.35 115.2 50.00 3.00 1.00 16.00 0.50 3.00 87.00 0.50 510 18.00 0.50 700 5.50 1.95 5.40 11.00 11.00 0.50 11.00 55.50 3.00 56.00 5.50 5.75

Maximum Concentration 7.57 1831 164.6 312 3700 13.00 7.30 96.00 0.50 53.00 500 15 2300 74.00 0.50 4000 22.00 6.40 11.00 51.00 140 8.00 150 260 7.00 270 90.00 24.00

20th%ile 6.10 154.8 30.46 99.84 9.00 2.00 0.58 5.60 0.50 2.00 51 0.50 198 6.60 0.50 294 4.36 1.60 4.22 8.38 6.80 0.50 6.80 41.06 2.00 46.00 2.50 2.72

80th%ile 6.58 331.5 111.06 216.76 158 4.00 1.54 26.20 0.50 5.00 260 1.00 814 25.20 0.50 932 9.62 2.24 7.54 20.80 19.80 2.50 19.80 114 3.30 110 9.20 17.40


PCCK03 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

Tota

l Sus

pend

ed S

olid

s @

103

-10

5o C (m

g/L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1




Maximum Concentration 7.18 365.2 135.1 240.5 680 7.00 0.80 11.00 0.50 4.00 470 0.50 540 16.00 0.50 590 12.00 2.50 8.00 24.00 98.00 2.50 98.00 140 3.00 130 27.00 44.00

20th%ile 6.13 127.16 68.00 73.58 5.00 2.00 0.10 2.00 0.50 0.50 37 0.50 150 5.00 0.50 170 4.48 1.90 4.36 6.98 11.60 2.50 11.60 30 2.00 38.00 2.50 2.66

80th%ile 6.60 218.62 120.2 131.22 50.00 4.00 0.50 7.00 0.50 2.00 140 0.50 380 11.00 0.50 320 8.00 2.32 6.88 15.60 20.20 2.50 20.20 100 3.00 85.60 26.00 18.80


PCCK04 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@

103-

105o C

(mg/

L)

Turb

idity

(NTU

)


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1


Minimum Concentration 5.58 63.80 40.10 38.35 5.00 0.50 0.05 0.50 0.50 0.50 16.00 0.50 30 0.50 0.50 23 4.50 1.70 3.90 7.70 2.50 2.50 2.50 13.00 2.00 46.00 2.50 0.70


Maximum Concentration 6.68 557 182.6 377 50.00 5.00 1.40 34.00 0.50 5.00 100 0.50 1300 35.00 0.50 1200 15.00 2.80 13.00 32.00 130 2.50 130 190 7.00 170 29.00 30.00

20th%ile 6.01 164.96 81.14 98.28 16.40 0.90 0.44 3.60 0.50 1.80 31.80 0.50 188 7.80 0.50 314 4.66 1.86 4.54 8.86 11.00 2.50 11.00 43.00 2.00 47.60 2.50 2.28

80th%ile 6.54 292.22 131.76 194.95 42.80 3.00 1.22 26.60 0.50 4.20 73.00 0.50 1120 29.80 0.50 1100 11.40 2.34 8.72 25.00 38.00 2.50 38.00 130 5.00 134 17.20 19.00

COPPERFIELD CREEK CATCHMENT Table 5: PCCK06 Summary Table

PCCK06 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1


Minimum

Concentration 4.31 18.90 6.54 20.30 5.00 0.50 0.05 0.50 0.50 0.50 71.00 0.5 2.5 0.5 0.5 3 0.5 1 0.05 0.8 0.05 0.05 0.05 0.25 0.50 2.50 2.50 2.50

Median

Concentration 6.49 114.7 77.7 54.6 49 1 0.05 0.5 0.5 1 450 0.5 480 1 0.5 60 1.3 1.8 5.6 2 19 2.5 19 2.2 2 11 5 10

Maximum

Concentration 7.64 1012 153.3 3575 1301 62 18 230 0.5 49 1600 7 6200 170 3 12000 29 4.20 43 81 45 45 45 510 8.8 400 79 64

20th%ile 6.21 57 56.24 33.15 20 0.5 0.05 0.5 0.5 0.5 262 0.5 16 0.5 0.5 14.2 0.8 1.4 4.6 1.4 14 0.5 14 0.5 2 7.2 2.5 4.9

80th%ile 6.79 208.60 115.90 130.65 248 2 1.18 20 0.5 2 830 0.5 606 13 0.5 940 3.32 2.2 7.4 8.6 24 2.5 24 41.2 3.4 35.8 16 24

Table 6: PCCK06B Summary Table

PCCK06B pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1


Minimum Concentration 5.90 24.90 15.00 23.30 5.00 0.50 0.05 0.50 0.50 0.50 1000 0.50 11.00 0.50 0.50 22.00 0.50 1.20 1.10 1.00 0.50 0.50 0.50 0.50 1.00 5.00 2.50 4.30


Maximum Concentration 8.85 296.7 139.3 179.4 350 2.00 2.20 20.00 0.50 6.00 1200 0.50 720 16.00 0.50 1300 4.80 2.80 11.00 11.00 35.00 2.50 35.00 67.00 6.00 55.00 24.00 33.00

20th%ile 6.55 44.08 46.32 29.25 33.60 0.50 0.05 0.50 0.50 0.50 252 0.50 19.00 0.50 0.50 32.60 0.80 1.30 4.72 1.46 16.40 0.50 16.40 0.60 2.00 8.00 2.50 7.76

80th%ile 7.03 111.62 88.12 48.10 164 2.00 0.60 6.00 0.50 2.00 860 0.50 224 6.40 0.50 388 2.74 2.14 6.72 5.96 25.60 2.50 25.60 23.60 3.80 31.40 12.00 26.00


PCCK16 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1




Maximum Concentration 7.75 487 154.5 2665 1300 5.00 1.20 3.00 1.00 11.00 2000 3.00 78.00 8.00 1.00 160 4.20 3.70 17.00 5.40 62.00 14.00 62.00 35.00 8.00 28.00 70.00 41.00

20th%ile 6.31 34.28 57.48 22.10 10.40 0.50 0.05 0.50 0.50 0.50 340 0.50 6.00 0.50 0.50 0.50 0.60 1.40 3.62 0.90 13.00 0.23 13.00 0.50 1.32 5.00 2.50 3.60

80th%ile 6.90 54.40 113.2 35.10 250 1.00 0.05 0.50 0.50 0.50 750 0.50 19.60 0.50 0.50 16.20 1.00 2.20 5.50 1.50 24.00 2.50 24.00 0.50 3.40 9.00 10.00 14.00


PCCK21 pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1




Maximum Concentration 7.42 118.6 148.3 62.65 1300 43.00 0.20 2.00 1.00 4.00 480 0.50 190 3.00 0.50 190 6.30 2.70 9.10 5.90 45.00 2.50 45.00 21.00 3.00 33.00 120 160

20th%ile 6.47 51.10 49.22 31.72 27.40 0.50 0.05 0.50 0.50 0.50 178 0.50 19.40 0.50 0.50 20.80 1.00 1.40 4.06 1.50 21.60 0.50 21.60 0.50 1.00 9.00 2.50 7.76

80th%ile 7.12 78.10 127.34 48.49 252 1.00 0.05 0.50 0.50 1.20 334 0.50 95.80 2.00 0.50 65.20 2.06 1.80 7.62 2.68 37.40 2.50 37.40 5.00 2.00 17.00 21.60 29.80

Table 9: PCPWD Summary Table

PCPWD pH

EC

(µS/

cm)

Dis

solv

ed O

xyge

n (%

L)

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L)

Zinc

(µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Alk

alin

ity (m

g/L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s (b

y ca

lcul

atio

n) (M

g C

aCO

3/L)

To

tal S

uspe

nded

Sol

ids

@ 1

03-

105o C

(mg/

L)

Turb

idity

(NTU

)

Upper trigger 7.5 250 120 508 140 0.8 40 5 9.4 3600 17 34 31 13 15


Detection Limit 10 1 0.1 1 1 1 10 1 5 1 1 1 0.03 0.03 0.03 0.03 0.1 0.1 0.1 0.5 0.5 1 5 0.1


Minimum

Concentration 3.41 3.94 2.30 66.80 300 2.00 7.20 160 0.50 4.00 31.00 3.00 38.30 100 0.50 7500 17.00 2.50 4.80 13.00 0.05 0.05 0.05 23.00 4.00 57.00 2.50 0.50

Median

Concentration 4.38 1627 74.20 962 2700 7.00 23.00 420 0.50 55.00 110 15.00 14000 290 0.50 22000 55.00 7.60 85.00 150 2.50 2.50 2.50 900 13.00 710 2.50 2.20

Maximum

Concentration 5.94 4402 150.1 1943.5 13000 18.00 77.00 1020 6.00 230 620 39.00 25000 710 4.00 53000 100 16 190 270 140 6.00 150 1700 1500 1400 1000 110

20th%ile 4.06 1199.6 52.32 682.5 1400 5.00 13.00 280 0.50 26.80 67.00 9.00 8700 160.00 0.50 13000 36.00 5.08 44.00 108 0.50 0.50 0.50 600 9.00 508 2.50 0.94

80th%ile 4.78 2406.8 124.74 1467.7 5064.2 9.60 34.60 660 0.50 104.4 220 28.00 18600 386 0.5 29000 75.00 11.00 140 210 2.50 2.50 2.50 1300 19.00 1000 16.00 16.40

Pine Creek Catchment

Table 1: Enterprise Pit Summary Table

Enterprise Pit pH

EC

(µS

/cm

)

Dis

solv

ed O

xyge

n (%

L)

TDS

(mg/

L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L

Zinc

µg

/L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Hyd

roxi

de (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Akl

alin

ity

(mg/

L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s by

cal

cula

tion

(mgC

aCO

3/L)

Tota

l Sus

pend

ed S

olid

s @

10

3-10

5oC

(mg/

L)

Turb

idity

(NTU

)

Detection Limit NA NA NA NA <10 <1 <0.1 <1 <1 <1 <10 <1 <5 <1 <1 <1 <0.03 <0.03 <0.03 <0.03 <0.1 <0.1 <0.1 <0.1 <0.5 <0.5 <1 <5 <5

Number of Results 11 11 7 7 10 10 10 10 10 10 10 10 10 10 5 10 10 10 10 10 10 10 10 10 10 10 10 10 0

Minimum Concentration 5.58 348.2 36.5 232.7 20 4 1.2 4 1 1 10 1 280 12 1 920 10 2.8 7.4 23 0.1 0.1 0.1 0.1 130 2 120 5 -

Median Concentration 6.23 417.8 76 254.8 42 4.5 1.5 8 1 3 26 1.5 520 23 1 1054 12 3.2 8.5 26 1 9 1 9 150 2.6 130 5 -

Maximum Concentration 7.22 482.7 113.3 287.3 110 8 1.7 15 1 5 67 2 760 27 1 1400 14 3.7 9.1 30 5 30 5 30 170 10 160 5 -

20th% 5.86 385.6 63.64 238.03 29.4 4 1.4 4.8 1 1.8 10.8 1 342 19 1 986 11 3.1 7.68 25 0.82 5 0.82 5 130 2 130 5 -

80th% 6.34 475.1 78.62 276.64 78.8 7 1.5 11 1 3.2 51.6 2 644 24.4 1 1200 13.2 3.6 8.9 29 5 16.8 5 16.8 160 3 150 5 -

Table 2: Gandy’s Pit Summary Table

Gandy’s Pit pH

EC

(µS

/cm

)

Dis

solv

ed O

xyge

n (%

L)

TDS

(mg/

L)

Alu

min

ium

(µg/

L)

Ars

enic

(µg/

L)

Cad

miu

m (µ

g/L)

Cob

alt (

µg/L

)

Chr

omiu

m (µ

g/L)

Cop

per (

µg/L

)

Iron

(µg/

L)

Lead

(µg/

L)

Man

gane

se (µ

g/L)

Nic

kel (

µg/L

)

Sel

eniu

m (µ

g/L

Zinc

µg/

L)

Cal

cium

(mg/

L)

Pot

assi

um (m

g/L)

Sod

ium

(mg/

L)

Mag

nesi

um (m

g/L)

Hyd

roxi

de (m

g/L)

Bic

arbo

nate

(mg/

L)

Car

bona

te (m

g/L)

Tota

l Akl

alin

ity

(mg/

L)

Sul

phat

e (m

g/L)

Chl

orid

e (m

g/L)

Har

dnes

s by

cal

cula

tion

(mgC

aCO

3/L)

Tota

l Sus

pend

ed S

olid

s @

10

3-10

5oC

(mg/

L)

Turb

idity

(NTU

)

Detection Limit NA <10 <1 <0.1 <1 <1 <1 <10 <1 <5 <1 <1 <1 <0.03 <0.03 <0.03 <0.03 <0.1 <0.1 <0.1 <0.1 <0.5 <0.5 <1 <5 <5

Number of Results 10 10 7 7 10 10 10 10 10 10 10 10 10 10 5 10 12 12 12 12 11 11 11 11 11 11 12 10 0

Minimum Concentration 5.47 299.8 17.90 180.7 10.00 2.00 0.10 1.00 1.00 1.00 10.00 1.00 110 1.00 1.00 57.00 11.00 2.00 5.30 13.00 0.10 0.10 0.10 0.10 80.00 1.70 830 5.00 -

Median Concentration 6.15 553.65 67.40 335.4 23.00 5.00 0.20 1.00 1.00 1.00 21.00 1.00 310 4.50 1.00 120 29.50 2.95 8.45 35.50 1.00 5.00 1.00 5.00 220 2.00 220 5.00 -

Maximum Concentration 7.49 678 127.5 383.5 64.00 11.00 0.70 4.00 1.00 4.00 230 1.00 840 6.00 1.00 250 36.00 3.70 11.00 41.00 5.00 12.00 5.00 12.00 270 9.00 260 32.00 -

20th% 5.9 397.8 60.74 249.6 10 4.8 0.2 1 1 1 11.6 1 150 3 1 87 19.4 2.72 6.84 24 1 1 1 1 130 2 146 5 -

80th% 6.82 669.4 88.04 378.3 40.4 7.4 0.3 1 1 2 76.4 1 416 5.2 1 142 33 3.58 9.5 38.8 5 6 5 6 240 3 240 6.2 -


Appendix C – Linear Regressions

Trend Analysis using Linear Regression with Significance = 0.05

LocCode ChemName Max Value LastLinear Trend Degrees of FreedomR2 t-test alpha

PCCK06 Alkalinity (Bicarbonate as CaCO3)No Up 1 9.44E-02 3.402082907

PCCK06 Alkalinity (Carbonate as CaCO3)No No Change 1 0 0

PCCK06 Alkalinity (total) as CaCO3No Up 1 9.44E-02 3.402082907

PCCK06 Aluminium No Down 1 6.86E-02 2.860376698

PCCK06 Arsenic No No Trend 1 1.78E-02 1.420160901

PCCK06 Cadmium No Down 1 3.93E-02 2.131560235

PCCK06 Calcium No No Trend 1 1.19E-02 1.166981587

PCCK06 Chloride No No Trend 1 1.88E-03 0.45702325

PCCK06 Chromium (III+VI) No No Change 1 0 0

PCCK06 Cobalt No Down 1 3.25E-02 1.932071683

PCCK06 Copper No Down 1 3.97E-02 2.142160509

PCCK06 EC (field) No No Trend 1 4.98E-03 1.204209055

PCCK06 Hardness as CaCO3 No No Trend 1 6.25E-03 0.828152029

PCCK06 Iron No No Trend 1 2.16E-04 0.155025252

PCCK06 Lead No No Trend 1 2.15E-02 1.561690069

PCCK06 Magnesium No No Trend 1 0.012626752 1.202110437

PCCK06 Manganese No No Trend 1 1.90E-02 1.465332367

PCCK06 Nickel No Down 1 3.13E-02 1.89277881

PCCK06 pH (Field) No Down 1 4.26E-02 3.586943924

PCCK06 Potassium No No Trend 1 8.27E-03 0.970782477

PCCK06 Selenium No Down 1 0.053109093 1.75636921

PCCK06 Sodium No No Trend 1 5.31E-03 0.776621466

PCCK06 Sulphate No No Trend 1 1.80E-02 1.440572265

PCCK06 Total Dissolved SolidsNo Up 1 0.120176279 4.511330833

PCCK06 Total Suspended SolidsNo No Trend 1 1.05E-04 0.107872696

PCCK06 Turbidity No No Trend 1 6.69E-02 1.514754564

PCCK06 Zinc No Down 1 3.42E-02 1.983391085

PCCK16 Alkalinity (Bicarbonate as CaCO3)No Up 1 7.23E-02 2.915109285

PCCK16 Alkalinity (Carbonate as CaCO3)No No Trend 1 6.84E-03 0.866140866

PCCK16 Alkalinity (total) as CaCO3No Up 1 7.54E-02 2.980386045



PCCK16 Cadmium No No Trend 1 1.92E-02 1.46662434

PCCK16 Calcium No No Trend 1 0.018249474 1.449318448


PCCK16 Chromium (III+VI) No No Trend 1 3.51E-03 0.605459828

PCCK16 Cobalt No No Trend 1 2.05E-05 4.75E-02

PCCK16 Copper No No Trend 1 6.31E-03 0.835932118

PCCK16 EC (field) No No Trend 1 4.97E-06 3.72E-02

PCCK16 Hardness as CaCO3 No Up 1 8.93E-02 3.299555082



PCCK16 Magnesium No Up 1 0.127379259 4.061400474

PCCK16 Manganese No Up 1 6.03E-02 2.656590701

PCCK16 Nickel No No Trend 1 8.28E-03 0.95845711



PCCK16 Selenium No No Trend 1 0.016239965 0.986901845

PCCK16 Sodium No Up 1 3.06E-02 1.889693599

PCCK16 Sulphate No Up 1 3.56E-02 2.00732112

PCCK16 Total Dissolved SolidsNo No Trend 1 4.10E-03 0.734687159

PCCK16 Total Suspended SolidsNo No Trend 1 0.020007515 1.484899584


PCCK16 Zinc No Down 1 4.08E-02 2.163340984

PCCK21 Alkalinity (Bicarbonate as CaCO3)No No Trend 1 2.77E-02 0.77305678


PCCK21 Alkalinity (total) as CaCO3No No Trend 1 2.77E-02 0.77305678

PCCK21 Aluminium No No Trend 1 3.09E-02 0.818588699

PCCK21 Arsenic Yes No Trend 1 9.39E-02 1.47495937


PCCK21 Calcium No No Trend 1 1.40E-04 5.55E-02



PCCK21 Cobalt No No Trend 1 2.32E-02 0.706846875



PCCK21 Hardness as CaCO3 No No Trend 1 0.002094428 0.209941199


PCCK21 Lead No No Change 1 0 0

PCCK21 Magnesium No No Trend 1 7.46E-05 0.040518651

PCCK21 Manganese Yes No Trend 1 3.44E-02 0.865477773


PCCK21 pH (Field) No Down 1 0.262319409 2.732691978


PCCK21 Selenium No No Change 1 0 0

PCCK21 Sodium No No Trend 1 0.014298668 0.564919361




PCCK21 Turbidity No No Trend 1 0.106485831 1.035658195

PCCK21 Zinc No No Trend 1 4.02E-02 0.937918676

Trend Analysis using Linear Regression with Significance = 0.05

LocCode ChemName Max Value Last Linear Trend Degrees of FreedomR2 t-test alpha


PCCK01 Alkalinity (total) as CaCO3No Up 1 0.10545133 2.303192868


PCCK01 Arsenic No Up 1 6.81E-02 1.752304015








PCCK01 Hardness as CaCO3No No Trend 1 2.86E-02 1.084697438



PCCK01 Magnesium No Up 1 0.10667724 2.212705507

PCCK01 Manganese No Up 1 0.14066562 2.62202925

PCCK01 Nickel No Down 1 6.39E-02 1.693186744



PCCK01 Selenium No No Trend 1 1.83E-02 0.52850133


PCCK01 Sulphate No No Trend 1 0.04250496 1.444443242





PCCK02 Alkalinity (Bicarbonate as CaCO3)No Up 1 0.29760151 2.603669007

PCCK02 Alkalinity (Bicarbonate as CaCO3)No No Trend

PCCK02 Alkalinity (Bicarbonate as CaCO3)No No Trend 1 1.83E-03 0.142056251


PCCK02 Alkalinity (Carbonate as CaCO3)No No Trend

PCCK02 Alkalinity (Carbonate as CaCO3)No No Trend 1 1.96E-04 4.65E-02

PCCK02 Alkalinity (total) as CaCO3No Up 1 0.29760151 2.603669007

PCCK02 Alkalinity (total) as CaCO3No No Trend

PCCK02 Alkalinity (total) as CaCO3No No Trend 1 0.00166809 0.135571588

PCCK02 Aluminium No No Trend 1 8.24E-04 0.114884228

PCCK02 Aluminium No No Trend

PCCK02 Aluminium No No Trend 1 0.20714737 1.695273688

PCCK02 Arsenic No No Trend 1 0.15764043 1.730394131

PCCK02 Arsenic No No Trend



PCCK02 Cadmium No No Trend

PCCK02 Cadmium No Down 1 0.2351818 1.8391582


PCCK02 Calcium No No Trend


PCCK02 Chloride No Up 1 0.27511387 2.385980984

PCCK02 Chloride No No Trend

PCCK02 Chloride No No Trend 1 0.16567406 1.477936324

PCCK02 Chromium (III+VI) No No Trend 1 0.11599813 1.306082423

PCCK02 Chromium (III+VI) No No Trend

PCCK02 Chromium (III+VI) No No Change 1 0 0


PCCK02 Cobalt No No Trend

PCCK02 Cobalt No Down 1 0.31505594 2.249378969

PCCK02 Copper No No Trend 1 3.03E-04 6.97E-02

PCCK02 Copper No No Trend

PCCK02 Copper No No Trend 1 0.22364305 1.780095563


PCCK02 EC (field) No No Trend



PCCK02 Hardness as CaCO3No No Trend



PCCK02 Iron No No Trend

PCCK02 Iron No Down 1 0.30389046 2.191371876


PCCK02 Lead No No Trend

PCCK02 Lead No Down 1 0.23192856 1.822521464

PCCK02 Magnesium No No Trend 1 3.04E-02 0.7085939

PCCK02 Magnesium No No Trend

PCCK02 Magnesium No No Trend 1 0.05548407 0.839595526

PCCK02 Manganese No No Trend 1 2.32E-02 0.616486163

PCCK02 Manganese No No Trend

PCCK02 Manganese No Down 1 0.24194229 1.873704528


PCCK02 Nickel No No Trend

PCCK02 Nickel No Down 1 0.22725525 1.798602825

PCCK02 pH (Field) No No Trend 1 1.97E-02 1.098593867

PCCK02 pH (Field) No No Trend

PCCK02 pH (Field) No No Trend 1 2.07E-03 0.322146838

PCCK02 Potassium No Down 1 0.17126041 1.818358176

PCCK02 Potassium No No Trend

PCCK02 Potassium No Down 1 0.26576619 2.084122786

PCCK02 Selenium No No Change 1 0 0


PCCK02 Sodium No No Trend

PCCK02 Sodium No Down 1 0.22375895 1.859869749

PCCK02 Sulphate No No Trend 1 0.04959569 0.913750748

PCCK02 Sulphate No No Trend



PCCK02 Total Dissolved SolidsNo No Trend



PCCK02 Total Suspended SolidsNo No Trend




PCCK02 Zinc No No Trend

PCCK02 Zinc No No Trend 1 0.19657562 1.640546943

GHD

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© GHD 2014

This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited. G:\43\22192\WP\Pine Creek WDL Report\35131 Final Rev 2.docx

Document Status

Rev No.

Author Reviewer Approved for Issue Name Signature Name Signature Date

0 J.Woodworth G.Metcalfe G.Metcalfe G.Metcalfe G.Metcalfe 15/08/14

1 J.Woodworth G.Metcalfe G.Metcalfe G.Metcalfe G.Metcalfe 21/08/14

2 J.Woodworth G.Metcalfe G.Metcalfe 26/08/14

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