OLYMPIC DAM Environmental Management and Monitoring Report 1 July 2010 – 30 June 2011

Report No. ODENV 050

1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT 1 JULY 2010 - 30 JUNE 2011 The Hon. Tom Koutsantonis MP Minister for Mineral Resources Development PO Box 2832 ADELAIDE SA 5001

DISTRIBUTION

Department of Primary Industries Chief Inspector of Mines 1 CD copy and Resources South Australia (PIRSA)

Department of Environment and CE Dept of Environment and Natural 1 CD copy Natural Resources (SA) Resources

Senior Scientific Officer – Pastoral Land 1 CD copy Management – Land and Biodiversity Services Principal Scientific Officer – Pastoral 1 CD copy Program

Environment Protection CE Environment Protection Authority 1 CD copy Authority (SA) EPA Licence Coordinator 1 CD copy Manager Mining and Environment 1 CD copy Group Radiation Protection Branch

Department For Water (SA) CE Dept For Water 1 CD copy Senior Hydrogeologist 1 CD copy

Great Artesian Basin The Chair 1 CD copy Coordinating Committee

South Australian Arid Lands The Chair 1 CD copy Natural Resources Management Board

EXECUTIVE SUMMARY Page i BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

INTERNAL DISTRIBUTION

BHP Billiton Adelaide President Uranium 1 CD copy Vice President External Affairs 1 CD copy Corporate Lawyer 1 CD copy Vice President HSEC (Health, Safety, 1 CD copy Environment and Community) Manager Sustainability 1 CD copy Manager Radiation Services 1 CD copy

BHP Billiton Olympic Dam Asset President 1 CD copy Head of Production 1 CD copy General Manager Mine 1 CD copy General Manager Surface 1 CD copy General Manager Services 1 CD copy Head of HSEC Manager Environment and Radiation 1 CD copy Superintendent Environment 1 CD copy Superintendent Radiation & Occupational 1 CD copy Hygiene Environment Section Library 2 hard copies 2 CD copies Records Centre 2 hard copies 1 CD copy

Page ii EXECUTIVE SUMMARY 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Table of Contents 1 EXECUTIVE SUMMARY ...... 2 1.1 Overview...... 2 1.2 Major Achievements ...... 2 1.3 Monitoring Summary ...... 2 1.4 Future Challenges ...... 4 2 ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION ...... 5 2.1 ID 01 Use of Resources – Water ...... 10 2.2 ID 01 Use of Resources - Land ...... 11 2.3 ID 02 Operation of Industrial Systems – Airborne Emissions ...... 18 2.4 ID 02 Operation of Industrial Systems – Hazardous Materials Spillage ...... 22 2.5 ID 03 Generation of Wastes – Tailings Storage System (TRS) ...... 25 2.6 ID 03 Generation of Wastes – General and Industrial Waste ...... 26 2.7 Conclusion ...... 28 3 GROUNDWATER MONITORING PROGRAM ...... 31 3.1 Groundwater Abstraction and Mine Water Balance ...... 31 3.2 Groundwater Levels ...... 37 3.3 Groundwater Quality...... 44 3.4 Use of Mine Water for Dust Suppression ...... 46 3.5 Conclusion ...... 48 4 GREAT ARTESIAN BASIN (GAB) WATER MONITORING PROGRAM ...... 49 5 FAUNA MONITORING PROGRAM ...... 50 5.1 Avifauna...... 50 5.2 Small Mammals and Reptiles ...... 52 5.3 Amphibians ...... 53 5.4 Feral and Abundant Species ...... 54 5.5 At-risk Species – Category 1a ...... 58 5.6 At-risk Species – Category 1b and 2 ...... 60 5.7 Fauna Losses ...... 62 5.8 Conclusion ...... 66 6 FLORA MONITORING PROGRAM ...... 68 6.1 Emission Impacts to Vegetation ...... 68 6.2 Long Term Changes to Perennial Vegetation ...... 71 6.3 Land Disturbance ...... 74 6.4 Pest Plants ...... 77 6.5 GAB Spring Vegetated Wetland Area ...... 87 6.6 At-risk Species – Category 1 ...... 88 6.7 At-risk Species – Categories 1b and 2 ...... 91 6.8 Conclusion ...... 92 7 AIRBORNE EMISSIONS MONITORING PROGRAM ...... 93

EXECUTIVE SUMMARY Page iii BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

7.1 Smelter 2 Emissions ...... 93 7.2 Calciner Emissions ...... 95 7.3 Slimes Treatment Plant Emissions ...... 96

7.4 Ambient Sulphur Dioxide (SO2) ...... 97 7.5 Fugitive Particulate ...... 101 7.6 Results/Discussion ...... 102 7.7 Raise Bore Ventilation Shaft Emissions ...... 108 7.8 Conclusion ...... 110 8 ENERGY USE AND GREENHOUSE GAS EMISSIONS ...... 111 8.1 Energy Use ...... 111 8.2 Greenhouse Gas Emissions ...... 112 8.3 Conclusion ...... 113 9 RADIATION DOSE TO MEMBERS OF THE PUBLIC MONITORING PROGRAM ...... 114 9.1 Dose to Members of the Public ...... 114 9.2 Conclusion ...... 122 10 WASTE MONITORING PROGRAM ...... 123 10.1 Tailings Storage Facility (TSF) ...... 123 10.2 Evaporation Ponds (EPs) ...... 136 10.3 Mine Water Disposal Pond (MWDP) ...... 141 10.4 Site and Olympic Village Sewage Ponds ...... 142 10.5 Waste Management Centre ...... 143 10.6 Miscellaneous Hazardous Wastes ...... 144 10.7 Conclusions ...... 145 11 REFERENCES ...... 146 12 GLOSSARY OF TERMS ...... 149 13 APPENDIX 1: SUMMARY OF EXTERNALLY REPORTABLE SPILLS ...... 152 14 APPENDIX 2: METEOROLOGICAL DATA ...... 153 15 APPENDIX 4: CONSULTANTS UTILISED BETWEEN 1 July 2010 – 30 June 2011 ...... 156

Page iv EXECUTIVE SUMMARY 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

List of Figures Figure 2-1: Rehabilitation of a road to the TSF5 soil stockpile ...... 13 Figure 2-2: Contours are created in northern TSF5 soil stockpile to reduce erosion and to help promote native vegetation growth ...... 14 Figure 2-3: BEFORE – regenerated Athel Pines along Eagle way ...... 15 Figure 2-4: AFTER – regenerating stumps were uprooted and left in situ ...... 15 Figure 2-5: Example of signage at Myall Grove drain outlet ...... 16 Figure 2-6: June 2011 dashboard ...... 17 Figure 2-7: Total notifiable emissions trend ...... 19 Figure 2-8: Salt damage to surrounding vegetation ...... 20 Figure 2-9: Site immediately after initial remediation works ...... 21 Figure 2-10: Vegetation recovering approx 12mths after initial remediation work ...... 21 Figure 2-11: Number of radioactive process material spill events recorded in each area FY07 to FY11...... 24 Figure 2-12: Area of liquor stored on TSF Cells 1 – 4 during FY11 ...... 27 Figure 2-13: Olympic Dam site layout ...... 29 Figure 3-1: Olympic Dam regional bore locations ...... 32 Figure 3-2: Olympic Dam site area bore locations ...... 33 Figure 3-3: Simplified Olympic Dam hydrogeological cross-section ...... 35 Figure 3-4: Site groundwater abstraction ...... 36 Figure 3-5: Mine water balance summary FY11 (ML/d) ...... 37 Figure 3-6: TSF area groundwater levels (mAHD) - Andamooka Limestone aquifer ...... 39 Figure 3-7: Change in groundwater elevation along an east-west cross- section from LT19 to LT18, through the centre of the TSF ...... 40 Figure 3-8: Groundwater levels for Andamooka Limestone bores in the vicinity of the TSF ...... 40 Figure 3-9: Groundwater levels for Andamooka Limestone bores in the vicinity of Roxby Downs (LR) and the Mine Water Pond (LM) ...... 41 Figure 3-10: Groundwater levels for exploration drill holes in the vicinity of the underground mine ...... 42 Figure 3-11: Mine area groundwater levels (mAHD) - Arcoona Quartzite aquifer ...... 43 Figure 3-12: Mine water sample 238U levels and upper limit, FY11 ...... 47 Figure 3-13: Mine water sample 226Ra levels and upper limit, FY11 ...... 48 Figure 5-1: Abundance of Crested Bellbirds (CBB) in each of the monitoring zones (± 1 standard error)...... 51 Figure 5-2: Abundance of insectivorous feeding flock (IFF) species in each of the monitoring zones (± 1 standard error)...... 51 Figure 5-3: Impact footprint of the bioindicator bird species during FY10 and FY11 periods...... 52 Figure 5-4: Impact footprint of reptiles and small mammals during FY10 and FY11 periods...... 53 Figure 5-5: Three sampling sessions moving average (per km2) for rabbit abundance at three transects in the Olympic Dam region ...... 56

EXECUTIVE SUMMARY Page v BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 5-6: Three sampling sessions moving average (per km2) for cat abundance at three transects in the Olympic Dam region ...... 57 Figure 5-7: Three sampling sessions moving average (per km2) for fox abundance at three transects in the Olympic Dam region ...... 57 Figure 5-8: Three sampling sessions moving average (per km2) for kangaroo abundance at three transects in the Olympic Dam region ...... 58 Figure 5-9: Monthly summary of weekly monitoring results for FY11, showing total number of animals (birds, mammals and reptiles) recorded within the TRS ...... 63 Figure 5-10: Quarterly summary of all weekly monitoring results, showing total number of animals (birds, mammals and reptiles) recorded within the TRS ...... 64 Figure 5-11: Monthly summary of opportunistic observation results for FY11, showing total number of animals (birds, mammals and reptiles) recorded within the TRS ...... 64 Figure 5-12: Monthly summary of number of water birds recorded at local non- toxic water bodies in comparison to TRS during FY11 ...... 65 Figure 6-1: Location of radial sample sites and front sites monitored in FY11 ...... 70 Figure 6-2: Modelled distribution of symptoms in FY11 in and about the operation ...... 71 Figure 6-3: Modelled surface of Simpson’s index. The contours represent the modelled level of dominance based on the values from the sample sites (red dots) ...... 74 Figure 6-4: Disturbance on the SML between June 2010 and July 2011 ...... 76 Figure 6-5: Athel Pine control efforts continued on the SML during FY11. Seven regenerating Athel Pine plants were controlled along Eagle Way. Photo taken 5 weeks after control efforts undertaken ...... 79 Figure 6-6: Control efforts of Innocent Weed within the Myall Grove reserve during summer FY11. Example of ‘Noxious Weed’ signage installed at earth drains in Roxby Downs, where Innocent Weed infestations are known to occur ...... 79 Figure 6-7: Distribution of Extreme and High risk weed species on the SML in FY11 ...... 80 Figure 6-8: Distribution of weed species at Olympic Dam Village (within the Municipal Lease) in FY11 ...... 81 Figure 6-9: Distribution of weed species in the Roxby Downs urban area (in the Municipal Lease) in FY11 ...... 82 Figure 6-10: Distribution of weed species in the Arid Recovery reserve in FY11 ...... 83 Figure 6-11: Distribution of weed species on Andamooka Station (including Andamooka township) in FY11 ...... 84 Figure 6-12: Distribution of weed species on Roxby Downs Station and Purple Downs Station in FY11 ...... 85 Figure 6-13: Distribution of weed species on Stuarts Creek Station in FY11 ...... 86 Figure 7-1: Calciner particulate emissions sample run averages ...... 96

Figure 7-2: Modelled maximum 1-hour average ground level SO2 concentration, FY11 ...... 98

Figure 7-3: Modelled maximum 24-hour average ground level SO2 concentration, FY11 ...... 99

Figure 7-4: Modelled average annual ground level SO2 concentration, FY11 ...... 100

Page vi EXECUTIVE SUMMARY 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 7-5: Passive dust monitoring site locations ...... 103 Figure 7-6: Annual passive dust deposition rates measured at monitoring sites, FY11 ...... 104 Figure 7-7: Dust deposition rate by month at sites south of Olympic Dam ...... 105 Figure 7-8: Annual dust deposition rate for sites south of Olympic Dam ...... 105 Figure 7-9: Annual 238U deposition rates measured at monitoring sites, FY11 ...... 106 Figure 7-10: Annual 238U deposition rate by site ...... 107 Figure 7-11: Modelled distribution of limestone dust deposition in FY11 ...... 108 Figure 7-12: Monthly average of daily salt deposition rate, at monitoring sites 100m from raise bore ...... 109 Figure 9-1: Environmental Radiation Monitoring Sites ...... 115 Figure 9-2: FY11 radon decay product monthly averages, including five-year trends ...... 117 238 Figure 9-3: U concentration for the previous 5 years (in TSP and PM10) ...... 118 230 Figure 9-4: Th concentration for the previous 5 years (in TSP and PM10) ...... 119 226 Figure 9-5: Ra concentration for the previous 5 years (in TSP and PM10) ...... 119 210 Figure 9-6: Pb concentration for the previous 5 years (in TSP and PM10) ...... 120 210 Figure 9-7: Po concentration for the previous 5 years (in TSP and PM10) ...... 120

Figure 9-8: Total TSP and PM10 concentration for the previous 5 years ...... 121 Figure 9-9: Total effective dose ...... 122 Figure 10-1: TSF Supernatant Pond areas ...... 124 Figure 10-2: TRS aerial photograph – July 2011 ...... 126 Figure 10-3: Tailings Solids, Liquor and Tailings Density as % Solids ...... 127 Figure 10-4: TSF Cell 4 Underdrainage Pumping Rate ...... 128 Figure 10-5: Elevation of tailings in TSF cells ...... 129 Figure 10-6: TSF Cells 1 – 4 Liquor Balance – Inputs, FY11 ...... 130 Figure 10-7: TSF Cells 1 – 4 Liquor Balance – Outputs, FY11 ...... 130 Figure 10-8: Location of perimeter features monitored regularly ...... 132 Figure 10-9: Photo of location 3 in August 2011 showing buttress ...... 133 Figure 10-10: Schematic cross section through south side of TSF Cell 1 – June 2011 ...... 133 Figure 10-11: TSF Cell 1 South Wall Piezometer Hydrographs ...... 134 Figure 10-12: TSF Cell 3 daily seepage liquor flow ...... 134 Figure 10-13: TSF Cell 3 liquor analyses ...... 135 Figure 10-14: Photograph of Location 13B looking North in July 2011 ...... 136 Figure 10-15: EP1 and EP2 Liquor Balance – cumulative apparent evaporation trends ...... 138 Figure 10-16: EP3 Liquor Balance – cumulative apparent evaporation trend ...... 139 Figure 10-17: EP4 Liquor Balance – cumulative apparent evaporation trend ...... 139 Figure 10-18: EP5 Liquor Balance – cumulative apparent evaporation trend ...... 140 Figure 10-19: All EP Liquor Balance – cumulative apparent evaporation ...... 140 Figure 10-20: Evaporation pond capacity ...... 141 Figure 14-1: Annual rainfall FY11 ...... 153 Figure 14-2: Wind rose, FY11 ...... 154 Figure 14-3: Corrected Wind rose, FY10 ...... 155

EXECUTIVE SUMMARY Page vii BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

List of Tables Table 2-1: FY11 EMP Implementation Summary ...... 6 Table 2-2: Olympic Dam Progressive Rehabilitation conducted prior to FY11 ...... 12 Table 3-1: Groundwater chemistry data for bores located in the vicinity of Olympic Dam ...... 45 Table 3-2: Upper limits for radionuclide content in dust suppression water ...... 46 Table 3-3: Radionuclide analysis for dust suppression water ...... 47 Table 5-1: Summary of rabbit, cat, fox and kangaroo numbers (per square kilometre), showing historical abundance, FY10 and FY11 ...... 56 Table 5-2: Cat stomach analysis results ...... 58 Table 5-3: Category 1b &2 species recorded in the Olympic Dam and wellfields region for FY11 ...... 61 Table 6-1: Areas of modelled impact for symptoms since FY07 and change between FY10 and FY11 (areas modelled to the nearest 50ha) ...... 70 Table 6-2: Changes in quadrat species counts FY10-11, for sites sampled in both years (n=44 sites) ...... 73 Table 6-3: Changes in the total number of plants FY07-11, for sites sampled in over those years ...... 73 Table 6-4: Areas of disturbance on the SML from June 2010 to July 2011 ...... 75 Table 6-5: Pest plant species that pose an extreme or high risk ...... 78 Table 6-6: Changes in Eriocaulon carsonii abundance, FY10 – FY11 (n=131) ...... 89 Table 6-7: Changes in Eriocaulon carsonii abundance, baseline – FY11 (n=103) ...... 90 Table 7-1: Smelter 2 Stack Sampling Results June 2011 ...... 94 Table 7-2: Measured particulate concentrations in Calciner Emissions (mg/Nm3) ...... 95 Table 7-3 Classification of limestone dust deposition on ground surfaces ...... 101 Table 7-4: Modelled impact footprint for limestone dust deposition and change FY10-FY11 (areas modelled to the nearest 50 ha) ...... 107 Table 8-1: Actual results of Energy Efficiency for June 2011 ...... 111 Table 8-2: Actual results of Carbon Equivalent Intensity for June 2011 ...... 113 Table 10-1: List of perimeter features including their location, discovery date and status ...... 131

Page viii EXECUTIVE SUMMARY BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

1 EXECUTIVE SUMMARY

1.1 Overview This report represents the first annual report under the approved three year FY11-FY13 Environmental Protection and Management Program (EPMP). Considerable progress against actions and improvement targets in the FY11 EMP was made during the reporting period, with 75 percent of actions completed. Actions not completed during the reporting period will be progressed as a priority during FY12.

1.2 Major Achievements Following is a list of major achievements for the reporting period:  Reducing flow of water from pastoral bores by 4ML/d from the FY08 baseline;  Maintaining an industrial water efficiency of 1.12kL/t at an annual production rate of 10Mt;  Updating the existing hydrogeological model to include additional spring groups and information from new monitoring bores;  The establishment of Energy and Water reduction cost curves to evaluate abatement opportunities;  The establishment of Energy and Water Steering committees, with representatives from all departments, to ensure a coordinated approach to energy and water management across site;  Reviewing our Environment and Indigenous Heritage Clearance Permit procedure to include the Native Vegetation Management Plan and Significant Environmental Benefit requirements;  Update and submission to Government of the 2011 Closure and Rehabilitation Plan;  Rehabilitation of TSF5 construction support areas; and,  Significant improvements in streamlining data collection of measurements of energy and greenhouse gas emission data.

1.3 Monitoring Summary During the reporting period, ongoing environmental monitoring activities were undertaken. The following are points of interest:  Peak groundwater level beneath the TSF for this reporting period was approximately 67mAHD. Levels are not expected to exceed the limit of 80mAHD (20m below the ground) within the next 12 months;  Slightly elevated concentrations of uranium continue to be detected in the groundwater beneath the mine water disposal pond and old mine water disposal pond. Measured values do not pose a health hazard due to the low concentrations and the salinity of the water, which restrict its use for human or animal consumption;  Radiation activity levels for dust suppression water were found to be consistent with those measured in FY10 and were all below the upper limit values;  Avifauna indicators show that the operation appears to have measurable impacts in close proximity to the operation. The extent appears similar to the previous year;  Gecko gravidity, reptile and small mammal indicators show that the operation appears to have observed impacts when in close proximity to the operation. High

Page 2 EXECUTIVE SUMMARY 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

numbers of the introduced House Mouse influenced scores from small mammal and reptile monitoring;  Kangaroo, rabbit and fox numbers were lower than the long term mean on all transects;  Several Category 2 listed species were recorded in the Olympic Dam SML area and the wellfields region. Three of the species recorded were within the TRS system and several other waterbird species have the potential to visit this area;  There were 348 fauna mortalities recorded during weekly monitoring at the TRS in FY11, which compares to 148 for the previous reporting period. This increase was largely due to introduced house mice (over 100 recorded). The TRS Fauna project continued in FY11;  The total area of detectable symptoms on vegetation for FY11 was 2,500ha. This is 100ha larger than that identified in FY10. Where areas were affected, there were likely to be slightly fewer plant symptoms than in FY10;  The estimated total area of disturbance that occurred between June 2010 and July 2011 was 423.8ha;  Above average rainfall in the year preceding and during FY11 resulted in a high number of pest plant infestations within the control area. Known infestation areas were monitored and controlled with a focus on Extreme risk species;  Whilst there were some changes in Eriocaulon carsonii cover for individual spring units between FY10 and FY11, the changes were not significant at the spring group or impact zone level;  Isokinetic sampling of the Main Smelter Stack and Acid Plant Tail Gas Stack indicated continued compliance with the requirements of EPA Licence 1301 and the Environment Protection (Air Quality) Policy 1994;  The results of sampling indicate that emissions from Calciner A and B met the requirements of the Environment Protection (Air Quality) Policy 1994;

 No exceedance of the NEPM for ambient air quality for SO2 occurred over Olympic Dam Village or Roxby Downs Township during the reporting period;  Dust and 238U deposition rates recorded during the reporting period were overall lower than those measured in previous periods due to above average rainfall throughout the year;  Salt deposition rates for RB10, RB16 and RB19 are comparable to previous reporting periods. Deposition around RB21 increased during the first half of FY11, but as a result of improvement works emissions have been significantly reduced for the remainder of the year;  The site wide performance for GHG emissions in FY11 was 0.60GJ/t material milled and 86kg CO2e/t material milled;  The dose to members of the public due to operation-related radon progeny at both RDS and ODV were below the detection limit of 0.040mSv;  The dose to members of the public due to operation-related radionuclides in dust at both RDS and ODV were below the detection limit of 0.008mSv;  An effective dose to members of the public of less than the detection limit of 0.048mSv/year was calculated when background dose calculations were subtracted from measured doses. This value was less than 5% of the legislative limit of 1mSv/year;  The region continued to experience above average rainfall during FY11 which has resulted in the recording of some of the lowest PM10 and radionuclide concentrations in recent history.

EXECUTIVE SUMMARY Page 3 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

 Rainfall for the reporting period was 88% higher than the long term median annual rainfall. As a result of the high rainfall and significantly higher tailings deposition, the proportion of decant to evaporation ponds and liquor retained in tailings was significantly higher than the previous reporting period;  The combined area of the supernatant ponds on TSF Cells 1–3 varied between 7.6ha and 25.0ha over the reporting period with an average of 15.6ha, an increase of 84% from the previous years average of 8.5ha;  The supernatant pond area on TSF Cell 4 varied between 22.6ha and 42.5ha over the reporting period with an average of 30.5ha, an increase of 68% from the previous years average of 18.2ha;  A number of dark areas with increased moisture were identified previously around the perimeter of the TSF and four additional areas have been identified in the current reporting period;  A filter blanket was constructed over Location 3 on the South Wall of TSF Cell 1 to minimise the risk of piping;  The results of the water balance indicate that the TSF has the capacity to dispose of excess liquor by evaporation although the unaccounted liquor may also include seepage from beach areas. Seepage from supernatant liquor ponds was estimated at 3% of liquor output;  Evaporation Pond 2 was recommissioned in November 2010, following problems with the wave barriers in the previous reporting period;  It is estimated that approximately 35,922m3 (loose fill) of general waste was transported to the Waste Management Centre in FY11;  Approximately 787m3 of paper and cardboard waste was collected for recycling in FY11; and,  It is estimated that approximately 7,917 tonnes of hazardous waste was disposed of within the SML in FY11.

1.4 Future Challenges  Continuing implementation of water use conservation and recycling initiatives, including the substitution of saline water for high quality water use;  Continuing implementation of energy efficiency projects;  Continuing to develop the Smelter Environmental Improvement Plan with aims to reduce the total smelter emission events;  Continuing investigations into management methods relating to interactions between the TRS and fauna species;  Continuing to develop, update and implement a strategy towards minimising radioactive waste produced from the mining and processing of ore;  Identifying further opportunities for improvement of general and industrial waste management practices on site;  Integration of DEIS/SEIS approval conditions to the EPMP documents for next Ministerial and Commonwealth Submission;  Preparation for a carbon price; and,  Streamlining data capture and reporting processes through the implementation of a central environmental data management system (EDMS).

Page 4 EXECUTIVE SUMMARY 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

2 ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION

This section includes a summary of actions and improvement targets (Table 2-1) identified for the financial year 2011 (FY11), from 1 July 2010 to 30 June 2011 under the approved three years FY11-FY13 Environmental Management Program (EMP) for Olympic Dam. Details of progress against these actions and improvement targets are provided in Table 2-1. The following progress indicators have been used to assist the reader in being able to quickly assess progress that has occurred during the reporting period:

= Activity or target achieved

= Significant progress towards achieving the activity or target

= Activity or target not achieved.

The approved FY11 EMP contained 68 actions with improvement targets to be achieved during the year. The performance against these commitments was:

= 75% = 9% = 16%

A plan showing the areas of the Olympic Dam site discussed in this report is provided in Figure 2-13.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 5 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Table 2-1: FY11 EMP Implementation Summary

ID 01 Use of Resources - Water ID 1.1 Great Artesian Basin (GAB) Pressure Reductions Targets FY11:

 Reduce Etadunna and Muloorina West pastoral flows by 4ML/day from the FY08 baseline  Maintain an industrial water efficiency of 1.12kL/t at an annual production rate of 10Mt.  Maintain a domestic water use target of 2.6ML/day. Action Plan FY11:  Remove Jackboot Bore as an assessment criteria monitoring point.  Update the existing GAB hydrogeology model based on new information and review of existing technical information.  Continue implementation of water use conservation and recycling initiatives.  Continue substitution of saline water for high quality water use. ID 01 Use of Resources – Land ID 1.2 Land Disturbance and Rehabilitation Targets FY11:

 Review EIHCP procedure to include requirements of the SEB NVMP. Action Plan FY11:  Identify and prioritise projects to clarify high risk assumptions identified in Olympic Dam

Rehabilitation and Closure Plan.  Continue EIHCP awareness sessions with influencing personnel and contractors as

required.  Continue to implement the site rehabilitation strategy.

ID 1.3 Spread of Pest Plants Targets FY11:

 Eradicate Athel Pines along Eagle Way on the SML through mechanical removal where past control efforts are deemed unsuccessful.

 Install signage at drain culverts where declared pest species are found. Action Plan FY11:  Continue to monitor and control all known Innocent Weed infestation. Address any new

infestations of Innocent Weed as required.

 Continue to progress control of Buffel Grass within the SML and Municipal Lease.  Continue to progress control of Athel Pines within the SML and at the Olympic Dam Aerodrome.

 Continue to improve community knowledge of local pest plant species. ID 01 Use of Resources – Energy and Greenhouse Gas Emissions ID 1.4 Climate Change Targets FY11:  To be developed by the Energy Excellence Program during FY10 and reported through the Olympic Dam Dashboard. Action Plan FY11: Continue implementation of the energy efficiency projects.   Improve energy and greenhouse gas emission data collection and measurement.

 Continue to establish and embed sound energy excellence procedures and systems.

Page 6 ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

ID 02 Operation of Industrial Systems – Airborne Emissions ID 2.1 Sulphur Dioxide Emissions Targets FY11:  Reduce unplanned Acid Plant bypass events by 5% of the FY10 target (to less than or equal

to 14 events).  Maintain Acid Plant Tails Gas Stack exceedances at the FY10 target (to less than or equal

to 16 events).  Reduce the total unplanned emission events by 5% of the FY10 target (less than or equal to

78 events). Action Plan FY11:  Implement the Smelter/Refinery Environmental Improvement Plan.

 Identify reductions to SO2 emissions after the Smelter maintenance shutdown. ID 2.2 Particulate Emissions Targets FY11:  Maintain annual average operational contributed PM10 concentration at sensitive receptors

at equal or below the assessment criteria (ID2.2 – 7). Action Plan FY11:  Continue with the annual Processing Environmental Improvement Plan process.  Continue with the annual Mining Environment Improvement Plan process. ID 2.3 Saline Aerosol Emissions Targets FY11:  Reduction in the deposition of salt (NaCl) from saline aerosol emissions at RB21 salt jars by 25% from the 2009 annual average (less than 1,066mg/m2/day). Action Plan FY11:  Remediate areas of saline contamination around RB21  Develop criteria for saline emission controls at raise bores and ensure future changes to controls meet the criteria  Install and repair fencing barricades to high priority raise bores according to the action plan developed in Q3 FY10. ID 2.4 Radioactive Emissions Targets FY11:  Annual operational component of radiation doses to members of the public remain below 0.3 mSv. Action Plan FY11:

 Continue with Monitoring Program Airborne Emissions FY11-13 and Radiation Dose to Members of the Public FY11-13. ID 02 Operation of Industrial Systems – Hazardous Materials Spillage ID 2.5 Chemicals/Hydrocarbon Spills Targets FY11:  Concentrator – recordable spills of chemicals and hydrocarbons less than or equal to 4.  Hydromet – recordable spills of chemicals and hydrocarbons less than or equal to 3.  Smelter – recordable spills of chemicals and hydrocarbons less than or equal to 5.  Refinery – No recordable spills of chemicals and hydrocarbons.  Infrastructure – recordable spills of chemicals and hydrocarbons less than or equal to 3.  Mine – recordable spills of chemicals and hydrocarbons less than or equal to 14.  Supply – recordable spills of chemicals and hydrocarbons less than or equal to 1.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 7 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Action Plan FY11:  Undertake annual site chemical/hydrocarbon audit and implement actions from this audit with regards to bunding criteria and implementation. ID 2.6 Radioactive Process Material Spills Targets FY11:  Concentrator – reduce recordable spills of radioactive process material by 10% of the FY10 target (to less than or equal to 14 spills).  Hydromet – maintain recordable spills of radioactive process material at the FY10 target (to less than or equal to 18 spills).  Smelter – reduce recordable spills of radioactive process material by 10% of the FY10 target (to less than or equal to 11 spills).  Refinery – maintain recordable spills of radioactive process material at the FY10 target (to less than or equal to 6 spills).  Infrastructure – maintain recordable spills of radioactive process material at the FY10 target (less than or equal to 4 spills).  Mine – maintain recordable spills of radioactive process material at the FY10 target (less than or equal to 5 spills). Action Plan FY11:  Continue with the annual Processing Environmental Improvement Plan process.  Continue with the annual Smelter/Refinery Environmental Improvement Plan process.  Continue with the annual Mining Environmental Improvement Plan process.  Develop an annual Infrastructure Environmental Improvement Plan. ID 03 Generation of Wastes – Tailing Storage System (TRS) ID 3.1 Embankment Stability Targets FY11:  Review the slope stability around the perimeter of TSF Cells 1-4 using actual measured pore

pressure distributions and confirm the factors of safety for embankment stability.  Install a buttress and filter at the toe of the western embankment of TSF Cell 3 and the

adjacent eastern section of the northern embankment of TSF Cell. Action Plan FY11:  Prepare a report on the embankment stability of TSF Cells 1 to 4 using actual pore pressure

monitoring data.  Complete the detailed design and construction of a buttress and filter at the toe of the western embankment of TSF Cell 3 and adjacent eastern section of the northern embankment of TSF Cell 4. Install de-watering bore in spine of cells 3/4 to try to intercept liquor.  ID 3.2 Seepage Targets FY11:  The groundwater level in the Andamooka Limestone aquifer outside the perimeter of TSF Cells 1 to 4 shall not rise above 80 metres AHD. Action Plan FY11: Identify and install additional liquor interception systems if required.  ID 3.3 Fauna Interaction Targets FY11: Initiate assessment of the potential for Sound ID as an on demand deterrent system.   Initiate assessment of the durability of the HDPE balls and netting within the TRS. Action Plan FY11: Continue trials of Sound ID acoustic recognition systems. 

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 Continue trials of HDPE netting and balls within the TRS. ID 03 Generation of Wastes – General and Industrial Waste ID 3.4 Solid Waste (Non Hazardous and Hazardous) Action Plan FY11:  Improve data availability and integrity for tracking of wastes from source to disposal.  Set targets for waste recycling based on collected data. ID 3.5 Radioactive Waste Targets FY11:  Maintain the area of liquor stored in the TRS below or equal to 22ha as a monthly average. Action Plan FY11:  Continue to develop, update and implement a strategy towards minimising radioactive waste

produced from the mining and processing of ore.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 9 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

2.1 ID 01 Use of Resources – Water 2.1.1 ID 1.1 Great Artesian Basin (GAB) Pressure Reductions Targets FY11:

 Reduce Etadunna and Muloorina West pastoral flows by 4ML/day from the FY08 baseline. Following the purchase of Etadunna and Muloorina West in 2009, pastoral flow rates have been reduced in an effort to conserve water. Flow rates from pastoral bores on these leases equalled 5.42ML/day in FY08. Flow rates measured during FY11 equalled 1.30ML/day – a reduction of 4.12ML/day over the period.

 Maintain an industrial water efficiency of 1.12kL/t at an annual production rate of 10Mt. The GAB Industrial Water Efficiency of the operation in FY11 was 1.07kL/t. Production for the year (total material milled) was 10.5Mt. The achievement of 1.07kL/t equalled FY09 as the most water efficient year on record for the operation.

 Maintain a domestic water use target of 2.6ML/day. Domestic water consumption for FY11 averaged 2.11ML/day, which achieved the target. Action Plan FY11:

 Remove Jackboot Bore as an assessment criteria monitoring point. Jackboot bore was removed as an assessment criteria monitoring point for Wellfield A for the FY12 reporting period, however it still applies to Wellfield B. Discussions are continuing regarding a proposal for the Ongoing Sustainable Management for the GAB and part of this includes identifying alternative monitoring points.

 Update the existing GAB hydrogeology model based on new information and review of existing technical information. Numerical models have been used for more than 15 years to simulate groundwater flow in the south-west Great Artesian Basin (GAB) and the influence of the wellfields supplying water to Olympic Dam and Roxby Township. Several groundwater models have been created, from the initial GAB95 model, through successive improvements and more and better data to the ODEX model families. The following improvements were completed during the reporting period:  ODEX6 was created to distinguish the new model from the previous version (ODEX5).  The ODEX6 model domain was extended to include the western springs, from Anna to Strangways; and to place new information from the new monitoring bores MB5 and MB6 into better hydrogeological context. • The ODEX6 model was reviewed and enhanced between Jackboot Bore and the western springs to improve drawdown predictions. New bore data and the results of recent hydrostratigraphic and geophysical work were included to the west of Jackboot Bore.

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• Monitoring (drawdown data) and abstractions, including pastorals and Moomba, were updated to June 2011. • The time periods ODEX6 uses were improved to better reflect the changes in wellfield abstractions related to the Clark Shaft outage.

 Continue implementation of water use conservation and recycling initiatives Implementation of the following water conservation and recycling initiatives began in FY11 and are expected to reduce water use in FY12:  Increasing the equipment capacity for recycling of tailings liquor to the metallurgical plant  Covering an open water storage at the desalination plant to reduce evaporative losses

 Continue substitution of saline water for high quality water use. Saline water continues to be used in lieu of high quality water where feasible, including use in CAF, road watering and construction. Saline water is not being used to augment the process water stream as this results in an unacceptable increase in chloride in the system, which effects plant performance. Research is continuing into overcoming the technical barriers of high chloride in the system and its negative impact. Implementation began on a project which will use saline water as a substitute for high quality water at the Mine vehicle wheelwash.

2.2 ID 01 Use of Resources - Land 2.2.1 ID 1.2 Land Disturbance and Rehabilitation Targets FY11:

 Review EIHCP procedure to include requirements of the SEB NVMP The Environmental and Indigenous Heritage Clearance Permit (EIHCP) procedure was reviewed to improve the efficiency of the process and to include requirements of the Significant Environmental Benefit (SEB) Native Vegetation Management Plan (NVMP) in FY11. Key outcomes from the review have resulted in:  Identification of areas subject to a SEB offset;  The addition of a SEB ratio attribute to the EIHCP spatial database;  Identification of process improvements to automate SEB offset accounting; and,  Identification of the requirement for a robust process and field guide for assessing SEB ratios. Continuous improvement will continue in FY12 to further improve the SEB accounting process by developing an assessment field guide and by further integrating SEB accounting requirements into the EIHCP and reporting procedure. Action Plan FY11:

 Identify and prioritise projects to clarify high risk assumptions identified in Olympic Dam Rehabilitation and Closure Plan. As part of updating Olympic Dam’s Closure and Rehabilitation Plan, the Life of Asset (LOA) Plan has been used to derive key assumptions in calculating the provision for

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 11 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT closure costs. Some of the assumptions applied in the Closure Plan were derived from the LOA Plan, namely:  The estimated life of the mine;  The useful life of the site plant and equipment as suggested in the LOA Plan;  Closure measures area referenced in the FY11 LOA Plan and defined in the Olympic Dam Closure Plan 2007. The FY12 Life of Asset Plan will reference closure measures as defined in the Olympic Dam Closure and Rehabilitation Plan 2011 – Submitted to Government (PIRSA) in August 2011;  Rehabilitation activities conducted in FY11 will be reported in the FY12 Life of Asset Plan; and,  Table 2-2 was provided by the Environment and Radiation Section for the Progressive Rehabilitation Plan document in May 2011.

Table 2-2: Olympic Dam Progressive Rehabilitation conducted prior to FY11

Facility Description Area Rehabilitated

Borefield Facilities Disturbance from the construction of 365.6ha the GAB water pipeline

Exploration Borrow pits, Drill pads, turkey nest 14.0ha

Metallurgical Facilities Unsealed road and mullock pile 6.4ha

Tailings Facilities Unsealed road 0.5ha

Miscellaneous Facilities Borrow pits, unsealed roads and other 28.0ha disturbances

Town Facilities Unsealed roads, Olympic Dam Camp 1 26.1ha and Camp E

TOTAL 440.6ha

 Note: Additional rehabilitation was undertaken of TSF5 stockpile areas and other areas no longer required. Rehabilitation of these areas took place following the submission of the Closure and Rehabilitation Plan and are not included in the table above. The FY11 Annual Closure and Rehabilitation Plan review included a Closure Planning Workshop in March 2011 and Risk Assessment Workshop in June 2011. These workshops were held with the relevant internal stakeholders. The following changes were considered to update the Closure Economic Evaluation and associated Closure Risk Register:  The mine closure date was decreased from 2084 to 2082;  No changes to Life of Asset tailings cells were required; and,  The FY12 Life of Asset Plan will update any changes. The Annual Closure Summary Report was completed by the Olympic Dam Resources Planning and Development and Finance Departments and sent to BHP Billiton Corporate.

 Continue EIHCP awareness sessions with influencing personnel and contractors as required.

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EIHCP awareness sessions, with current information, were undertaken with key personnel and contractors. This included presentations to influencing personnel from the TSF5 construction crew, mine projects, services, exploration and drilling, and backfill. Sessions will continue throughout FY12.

 Continue to implement the site rehabilitation strategy. With the underground nature of the operation and awareness of a possible future expansion, large scale rehabilitation works were not undertaken during FY11. EIHCP conditions require temporary disturbances to be rehabilitated where possible. This is the case for excavation works to lay cable or fix burst pipes where topsoil is respread and the earth lightly ripped to promote natural revegetation. All areas cleared for the construction of TSF5 that are no longer required for ongoing operation have been rehabilitated. This includes adding bunds into long term stockpiles to prevent erosion and ripping up compacted laydown areas (Figure 2-1 to Figure 2-2).

Figure 2-1: Rehabilitation of a road to the TSF5 soil stockpile

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 13 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 2-2: Contours are created in northern TSF5 soil stockpile to reduce erosion and to help promote native vegetation growth 2.2.2 ID 1.3 Spread of Pest Plants Targets FY11:

 Eradicate Athel Pines along Eagle Way on the SML through mechanical removal where past control efforts are deemed unsuccessful.

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Seven regenerating Athel Pine trees were up-rooted along Eagle Way during FY11. Past cut and swab control efforts were unsuccessful, so mechanical removal was instigated and no regeneration has been noted since. Trees ranged from 1m to 3m in height and were removed from the ground using a small excavator. Figure 2-3 and Figure 2-4 show before and after photos of Athel Pine removal efforts.

Figure 2-3: BEFORE – regenerated Athel Pines along Eagle way

Figure 2-4: AFTER – regenerating stumps were uprooted and left in situ

 Install signage at drain culverts where declared pest species are found. Signage displaying information regarding the presence of noxious weeds were installed at four earth drain heads within Roxby Downs, in consultation with the Roxby Downs Municipal Council. Signs were installed where infestations of Innocent Weed were known to occur and there was a risk of contaminated soil being removed for maintenance requirements (Figure 2-5).

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 15 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 2-5: Example of signage at Myall Grove drain outlet Action Plan FY11:

 Continue to monitor and control all known Innocent Weed infestations. Address any new infestation of Innocent Weed as required. Innocent weed was present at known infestation locations during the summer of FY11. Extensive physical and chemical control was undertaken on numerous occasions. Despite flooding of several drainage areas where Innocent Weed occurs during FY10 and the substantial rainfall throughout FY11, the Myall Grove infestation area appeared to be smaller and less dense than in previous years. Infestations found in earth drains that run into the larger Myall Grove reserve area continue to be actively controlled as a priority.

 Continue to progress control of Buffel Grass within the SML and Municipal Lease. During FY11 Buffel Grass was monitored and controlled, using a combination of spot spraying and hand-pulling. The distribution of this weed has in the past been largely limited to the northern sections of Roxby Downs, particularly around the town water supply and light industrial area. During FY11, infestations of significant size were controlled along B97 Highway (Woomera to Olympic Dam). Individual infestations continue to be controlled on the Special Mining Lease and appear to be decreasing in density. Opportunistic monitoring, especially following rain, will continue in FY12.

 Continue to progress control of Athel Pines within the SML and at the Olympic Dam Aerodrome. Progress of Athel Pine control is detailed in the ‘Targets FY11’ section of ID 1.3, above.

 Continue to improve community knowledge of local pest plant species.

During FY11, articles on ‘Pest Plants’ and the use of ‘native species’ for landscaping were submitted and published in local newspapers. Internal BHP Billiton notifications were also sent in relation to common weed species following the substantial rainfall events throughout FY11. Two Weed Management Group meetings were held during FY11, attended by regional stakeholders and government representatives.

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2.2.3 ID 01 Use of Resources – Energy & Greenhouse Gas Emissions 2.2.4 ID 1.4 Climate Change Targets FY11:

 To be developed by the Energy Excellence Program during FY10 and reported through the Olympic Dam Dashboard. Targets for energy efficiency and greenhouse gas emissions (carbon equivalent intensity) were set for each month and reported through the Olympic Dam dashboard. Figure 2-6 shows the June 2011 results as an example. It gives the June actuals and targets and the year to date (YTD – i.e. overall result for 2011) actuals and targets. Figure 2-6 shows that overall site was close to target for energy efficiency and carbon equivalent intensity. Some of the individual plant areas achieved target and some were over target.

Figure 2-6: June 2011 dashboard The reason targets were not met was more related to the quality of targets, rather than a reflection of performance. FY11 was the first year targets were set in this way, since then the understanding of the drivers of energy use and greenhouse gas emissions has improved. These learnings will be applied when setting future targets. Action Plan FY11:

 Continue implementation of the energy efficiency projects. Progress was made on projects that had an energy benefit in FY11. This was documented as part of the requirements of the federal government’s Energy Efficiency Opportunities (EEO) legislation.

 Improve energy and greenhouse gas emission data collection and measurement. Significant improvements in streamlining data collection and measurements were made in FY11. This has reduced the time for the collation of routine monthly reports from a full day to several hours. Changes have also resulted in improved accuracy of departmental energy use and greenhouse gas emissions and for site as a whole. This in turn has facilitated a better understanding of the drivers of variation in energy use and greenhouse gas emissions.

 Continue to establish and embed sound energy excellence procedures and systems.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 17 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Existing procedures covering the monitoring of energy use and greenhouse gas emissions, and the energy and greenhouse gas management plan were reviewed and updated. An Energy Steering Committee was formed and imbedded in FY11, which brings together key personnel from across site to coordinate improvement actions and drive accountability for energy performance. The committee is chaired by the Manager – Environment and Radiation.

2.3 ID 02 Operation of Industrial Systems – Airborne Emissions 2.3.1 ID 2.1 Sulphur Dioxide Emissions Targets FY11:

 Reduce unplanned Acid Plant bypass events by 5% of the FY10 target (to less than or equal to 14 events). In FY11 a change was made to the way emission events were tracked and reported. This change was made in order to shift the focus on reducing overall notifiable emission events. This was done by reviewing the internal definition around planned and unplanned events and tracking our total notifiable events rather than unplanned events. As a result of this change a target for total notifiable Acid Plant bypass events was determined. The FY11 target for Acid Plant bypass events was 23. This represents both unplanned and planned events. Actual number of Acid Plant bypass events in FY11 was 46. This represents a 100% increase in the target number.

 Maintain Acid Plant Tails Stack exceedances at the FY10 target (to less than or equal to 16 events). Acid Plant Tails Stack exceedances were 119% above target, with 35 events recorded.

 Reduce the total unplanned emission events by 5% of the FY10 target (less than or equal to 78 events). In FY11 a change was made to the way emission events were tracked and reported. This change was made in order to shift the focus on reducing overall notifiable emission events. This was done by reviewing the internal definition around planned and unplanned events and tracking our total notifiable events rather than unplanned events. As a result of this change a target for total notifiable emission events was determined based on a 5% reduction of the FY04-09 average. The FY11 target for total notifiable emission events was 196. The actual result for FY11 was 194 total notifiable emission events, which is under target. (Figure 2-7). When compared with the total emissions from FY09, this is a 25% reduction in the total number of emissions notifiable to Government. Because FY10 does not represent a full production year, the data has been compared with the FY09 period.

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300

250

200

150

100

50 Number of emissionevents

0 FY06 FY07 FY08 FY09 FY10 FY11

Total Notifiable Emission Events Acid Plant Tails Stack Exceedances Acid Plant Bypass Events

Figure 2-7: Total notifiable emissions trend Action Plan FY11:

 Implement the Smelter/Refinery Environmental Improvement Plan. An action plan was developed and implemented throughout FY11. This was reviewed periodically and most actions deemed relevant were completed during FY11. The few outstanding actions will be considered in the FY12 EIP process. A significant focus was put in by the operations area in the EIP to reduce bypass events associated with the anode furnace off gas area. As a result a large reduction in emissions was observed during FY11 from this area.

 Identify reductions to SO2 emissions after the Smelter maintenance shutdown. As a result of the Smelter maintenance shutdown that occurred in FY10 a decrease in emissions was not observed. Due to equipment being offline for an extended period of time, emission events increased due to a failure with the variable speed drive on the anode furnace four off-gas fan. 2.3.2 ID 2.2 Particulate Emissions Targets FY11:

 Maintain annual average operational contributed PM10 concentration at sensitive receptors at equal or below the assessment criteria (ID2.2 – 7). Annual average PM10 concentrations at Olympic Dam Village (ODV) and Roxby Downs (RDS) for FY11 were below 30µg/m3. PM10 concentrations peaked in September 2010 at ODV and RDS, at 18µg/m3 and 25µg/m3, respectively. Annual average concentrations for ODV and RDS were 10.5µg/m3 and 11.1µg/m3, respectively. Action Plan FY11:

 Continue with the annual Processing Environmental Improvement Plan process.

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An action plan was developed and implemented throughout FY11. This was reviewed periodically and most actions deemed relevant were completed during FY11. The few outstanding actions will be considered in the FY12 EIP process.

 Continue with the annual Mining Environment Improvement Plan process. An EIP for the mine has been initiated, focusing on saline aerosol emissions from raise bores and improving controls as well as hydrocarbon management. Outstanding actions will be considered in the FY12 EIP process. 2.3.3 ID 2.3 Saline Aerosol Emissions Targets FY11:

 Reduction in the deposition of salt (NaCl) from saline aerosol emissions at RB21 salt jars by 25% from the 2009 annual average (less than 1,066mg/m2/day). The RB21 mist eliminators were repaired in January 2010, which substantially reduced salt emissions. The FY11 annual average RB21 salt deposition result was 358mg/m2/day. RB21 salt deposition peaked in February 2011 at 1,220mg/m2/day. Action Plan FY11:

 Remediate areas of saline contamination around RB21. During FY11 contaminated soil was removed from the eastern area surrounding RB21. Following substantial rainfall throughout the reporting period, annual and some perennial vegetation has re-established in areas previously impacted from salt deposition, see Figure 2-8, Figure 2-9 and Figure 2-10 below.

Figure 2-8: Salt damage to surrounding vegetation

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Figure 2-9: Site immediately after initial remediation works

Figure 2-10: Vegetation recovering approx 12mths after initial remediation work

 Develop criteria for saline emission controls at raise bores and ensure future changes to controls meet the criteria. Saline emission controls at raise bores have been identified and are currently being tested. Suggested controls are the installation of mist eliminators and cement wall fencing around barricades. An investigation is currently underway with a contract company to upgrade the mist eliminators and increase the raisebore fan performance, therefore reducing the need for strenuous maintenance caused by the current maintenance regime. Further investigation will also focus on the possibility of using shade cloth as an extra emission prevention device by extending it from the top of the concrete barriers to the top of the fan outlet.

 Install and repair fencing barricades to high priority raise bores according to action plan developed in Q3 FY10.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 21 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

The installation of cement barricades to high priority raise bores are tracking well within the set timeframes, with no major problems. 2.3.4 ID 2.4 Radioactive Emissions Targets FY11:

 Annual operational component of radiation doses to members of the public remain below 0.3mSv. Operational component of radiation doses to members of the public at Olympic Dam and Roxby Downs remained below the detection limit of 0.048mSv/year. Action Plan FY11:

 Continue with Monitoring Program Airborne Emissions FY11-13 2788 and Radiation Dose to Members of the Public FY11-13 2790. Monitoring programs continue to be executed without any changes.

2.4 ID 02 Operation of Industrial Systems – Hazardous Materials Spillage 2.4.1 ID 2.5 Chemicals/Hydrocarbon Spills Targets FY11:

 Concentrator – recordable spills of chemicals and hydrocarbons less than or equal to 4. Recordable spills of chemicals and hydrocarbons in the Concentrator were 25% above target with 5 events recorded in FY11.  Hydromet – recordable spills of chemicals and hydrocarbons less than or equal to 3. Recordable spills of chemicals and hydrocarbons in the Hydromet were 100% below target with no events recorded in FY11.

 Smelter – recordable spills of chemicals and hydrocarbons less than or equal to 5. Recordable spills of chemicals and hydrocarbons in the Smelter were 20% below target with 4 events recorded in FY11.

 Refinery – no recordable spills of chemicals and hydrocarbons. Recordable spills of chemicals and hydrocarbons in the Refinery were above target with 2 events recorded in FY11.

 Infrastructure – recordable spills of chemicals and hydrocarbons less than or equal to 3. Recordable spills of chemicals and hydrocarbons in Services were above target with 4 events recorded in FY11.

 Mine – recordable spills of chemicals and hydrocarbons less than or equal to 14. Recordable spills of chemicals and hydrocarbons at the Mine were below target with 5 events recorded.

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 Supply – recordable spills of chemicals and hydrocarbons less than or equal to 1. Recordable spills of chemicals and hydrocarbons in Supply were above target with 2 events recorded in FY11. Action Plan FY11:

 Undertake annual site chemical/hydrocarbon audit and implement actions from this audit with regards to bunding criteria and implementation. The annual site Hydrocarbon Audit was conducted and an action plan developed for each area. The main recommendations related to specific hydrocarbon management in some areas within the surface Mine workshops and the underground mine fuel bay, including provision of spills kits and improving storage areas and bunds to avoid and capture any spillages. The main recommendation for Processing and Smelter was to improve bunds in storage areas through correct use and provision of appropriate/additional facilities. The standard of housekeeping could also be improved within each area with emphasis on increasing ownership and education. 2.4.2 ID 2.6 Radioactive Process Material Spills Targets FY11: All spills of radioactive process material during the reporting period occurred within the plant and TRS areas and did not result in harm to the environment or radiation risk to personnel.

 Concentrator – reduce recordable spills of radioactive process material by 10% of the FY10 target (to less than or equal to 14 spills). Recordable spills of radioactive process materials in the Concentrator were 21% above target with 17 events recorded in FY11. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11.

 Hydromet – maintain recordable spills of radioactive process material at the FY10 target (to less than or equal to 18 spills). Recordable spills of radioactive process materials in the Hydromet were 22% above target with 22 events recorded. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11.

 Smelter – reduce recordable spills of radioactive process material by 10% of the FY10 target (to less than or equal to 11 spills). Recordable spills of radioactive process materials in the Smelter were 18% below target with 9 events recorded. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11.

 Refinery – maintain recordable spills of radioactive process material at the FY10 target (to less than or equal to 6 spills). Recordable spills of radioactive process materials in the Refinery were 67% below target with 2 events recorded. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11.

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 Infrastructure – maintain recordable spills of radioactive process material at the FY10 target (less than or equal to 4 spills). Recordable spills of radioactive process materials within Infrastructure were above target with 5 events recorded. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11.

45

40

35

30

25

20

Number of spill events 15

10

5

0 Concentrator Hydromet Smelter Refinery Mine Infrastructure

FY07 FY08 FY09 FY10 FY11 Figure 2-11: Number of radioactive process material spill events recorded in each area FY07 to FY11.

 Mine – maintain recordable spills of radioactive process material at the FY10 target (less than or equal to 5 spills). Recordable spills of radioactive process materials at the Mine were below target with 3 events recorded. Figure 2-11 shows the number of recordable spills of radioactive process material in FY11. Action Plan FY11:

 Continue with the annual Processing Environmental Improvement Plan process. An action plan was developed and implemented throughout FY11. This was reviewed periodically and most actions deemed relevant were completed during FY11. The few outstanding actions will be considered in the FY12 EIP process.

 Continue with the annual Smelter / Refinery Environmental Improvement Plan process. An action plan was developed and implemented throughout FY11. This was reviewed periodically and most actions deemed relevant were completed during FY11. The few outstanding actions will be considered in the FY12 EIP process.

 Continue with the annual Mining Environmental Improvement Plan process.

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An EIP for the mine was developed and implemented throughout FY11. Outstanding actions will be considered in the FY12 EIP process.

 Develop an annual Infrastructure Environmental Improvement Plan. The FY11 Infrastructure EIP was developed during the reporting period with actions entered and tracked within First Priority (FPe), an internal system for HSE management.

2.5 ID 03 Generation of Wastes – Tailings Storage System (TRS) 2.5.1 ID 3.1 Embankment Stability Targets FY11:

 Review the slope stability around the perimeter of TSF Cells 1-4 using actual measured pore pressure distributions and confirm the factors of safety for embankment stability. Geotechnical drilling and testing was undertaken around the perimeter of TSF Cells 1-3 during FY11. A review of the stability of TSF Cells 1-3 was undertaken using this information, as well as actual pore pressure measurements.

 Install a buttress and filter at the toe of the western embankment of TSF Cell 3 and the adjacent eastern section of the northern embankment of TSF Cell 4. The buttress was installed during FY10 as planned. Refer to Section 10 – Waste for more detail. Action Plan FY11:

 Prepare a report on the embankment stability of TSF Cells 1 to 4 using actual pore pressure monitoring data. A report was prepared on the stability of TSF Cells 1-3 during FY11 based on results from geotechnical investigations.

 Complete the detailed design and construction of a buttress and filter at the toe of the western embankment of TSF Cell 3 and adjacent eastern section of the northern embankment of TSF Cell 4. The buttress was installed during FY10 as planned.

 Install de-watering bore in spine of cells 3/4 to try to intercept liquor. A de-watering bore was installed during the reporting period into the mullock spine separating TSF Cell 3 and TSF Cell 4. This was successfully commissioned and has reduced seepage reporting to the Cell 3/4 Buttress by over 95%. Refer to Section 10 – Waste for more detail. 2.5.2 ID 3.2 Seepage Targets FY11:

 The groundwater level in the Andamooka Limestone aquifer outside the perimeter of TSF Cells 1 to 4 shall not rise above 80 metres AHD. The groundwater level in the Andamooka Limestone aquifer outside the perimeter of TSF Cells 1-4 did not rise above 80m AHD during the reporting period. The maximum level during FY11 was 67.26m AHD.

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 25 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Action Plan FY11:

 Identify and install additional liquor interception systems if required. A liquor interception system is planned to be installed at Location 13A/B during FY12 as a precautionary measure. No other locations requiring liquor interception systems were identified during FY11. 2.5.3 ID 3.3 Fauna Interaction Targets FY11:

 Initiate assessment of the potential for Sound ID as an on demand deterrent system. Completed, refer to comments under action plan FY11.

 Initiate assessment of the durability of the HDPE balls and netting within the TRS. Completed, refer to comments under action plan FY11. Action Plan FY11:

 Continue trials of Sound ID acoustic recognition systems Trials of sound identification software continued, to determine its efficacy at identifying waterbird species and its potential use as part of an on demand deterrent system. At this stage the SoundID system will be investigated, plans for the Marine Radar have been put on hold pending the outcomes of the SoundID trial. Assessments suggest that SoundID has the potential to be equally or more effective than a marine radar system.

 Continue trials of HDPE netting and balls within the TRS HDPE netting and balls remained in place and were monitored throughout the reporting period. Trials are planned to continue to determine longer term durability of the materials.

2.6 ID 03 Generation of Wastes – General and Industrial Waste 2.6.1 ID 3.4 Solid Waste (Non Hazardous and Hazardous) Action Plan FY11:

 Improve data availability and integrity for tracking of wastes from source to disposal. Several aspects of data availability and integrity were improved during FY11. The main improvement was in the recording of waste disposed to landfill. Historically recyclable material diverted from landfill wasn’t recorded, leading to an overestimation in waste disposed to landfill. Data management has been improved so that these values can be recorded and a more accurate figure calculated. Volumes of material reused around site are also captured, leading to improved data availability and integrity. Data availability has also been improved by the addition of a monthly summary for major inputs and outputs from the Resource Recovery Centre. Percentages of material to landfill, material recovered from landfill and material delivered to recycling point are reported on monthly.

 Set targets for waste recycling based on collected data. Based on the improved data availability and integrity, targets have been set for FY12.

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2.6.2 ID 3.5 Radioactive Waste Targets FY11:

 Maintain the area of liquor stored in the TRS below or equal to 22ha as a monthly average. The area of liquor stored in the TRS averaged 45.1ha over the reporting period with a June 2011 value of 53.5ha (Figure 2-12). Liquor area remained over target during the year due to ongoing issues with above average rainfall of 278mm, low tailings densities and reduced evaporation pond capacity.

60

50

40

30

Hectares 20

10

0 Jul-10 Jan-11 Apr-11 Jun-11 Oct-10 Nov-10 Feb-11 Mar-11 Aug-10 Sep-10 Dec-10 May-11

Target Actual Figure 2-12: Area of liquor stored on TSF Cells 1 – 4 during FY11 Action Plan FY11:

 Continue to develop, update and implement a strategy towards minimising radioactive waste produced from the mining and processing of ore. Whilst no strategy document has been produced, current work on reducing radioactive waste is around disposal of redundant contaminated plant items. Minimisation of ore tailings material is generally limited to improvements in processing recoveries and efficiencies (i.e. reducing water and reagent input to limit overall volume of tails produced) and use of tailings sands as mine backfill material. A project is underway to replace the defective uranium solvent extraction crud centrifuge. Without the centrifuge operating waste volume is greater as process liquids are entrained in the crud. The centrifuge separates the crud into solids, aqueous liquor and organic solvent. This allows for the aqueous and organic to be recycled reducing water and solvent input and minimising the volume of material sent to the TSF. There are a number of demolition projects scheduled for the upcoming financial year to remove redundant plant. The Environment and Radiation section are assisting project planners assess the radioactive contamination levels in order to minimise the volume of material that will be classified as radioactive waste. Projects currently scheduled include the pilot plant and the pregnant leach solution sand filters. Scoping projects may also commence for demolition of smelter 1 and the old extraction plant. Investigation has also commenced on alternative storage options for redundant contaminated plant classified as low level radioactive waste (LLRW). LLRW is currently

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 27 BHP BILLITON OLYMPIC DAM 1 JULY 2009 – 30 JUNE 2010 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT disposed into the TSF and there is a quantity stored at the Resource Recovery Centre. The investigation will look at the feasibility of alternative sites which may be able to be made into compliant storage facilities, e.g. the old mine water disposal pond and the quarry.

2.7 Conclusion FY11 saw 75% of our targets and actions achieved; an increase of 6% from the previous reporting period. Significant progress was made on 9% of our actions and targets whilst 16% were not met. Targets met include:  Reducing flow of water from pastoral bores by 4ML/d from the FY08 baseline;  Maintaining and industrial water efficiency of 1.12kL/t at an annual production rate of 10Mt;  Updating the existing hydrogeological model to include additional spring groups and information from new monitoring bores;  Reviewing our Environment and Indigenous Heritage Clearance Permit procedure to include the Native Vegetation Management Plan and Significant Environmental Benefit requirements;  Updating the Closure and Rehabilitation Plan;  Rehabilitation of TSF5 construction support areas;  The groundwater level in the Andamooka Limestone aquifer outside the perimeter of TSF Cells 1-4 did not rise above 80m AHD during the reporting period. The maximum level during FY11 was 67.26m AHD;  Significant improvements in streamlining data collection of measurements of energy and greenhouse gas emission data;  Remediation of saline contamination areas around RB21; and,  Installation of a buttress and filter on the northwest corner of TSF Cell 3. Targets not met included:  Three targets relating to the reduction of SO2 emissions;  Four targets relating to the number of spills of chemicals and hydrocarbons;  Three targets relating to the number of spills of radioactive process material; and,  One target relating to area of liquor stored on the TSF due to above average rainfall and reduced capacity of evaporation ponds contributing to increased area of liquor on TSF;  Continuation of trials of the SoundID acoustic recognition system for potential use as an on-demand deterrent at the TRS

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Figure 2-13: Olympic Dam site layout

ENVIRONMENTAL MANAGEMENT PROGRAM (EMP) IMPLEMENTATION Page 29 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

3 GROUNDWATER MONITORING PROGRAM

3.1 Groundwater Abstraction and Mine Water Balance 3.1.1 Background Olympic Dam abstracts groundwater from both aquifer systems within the Special Mining Lease. The shallow Andamooka Limestone is completely dewatered in the mine area with inflows into the mine only from the deeper quartzite aquifer. In the TSF area and around the process plant there is considerable saturated thickness in the limestone due to seepage induced mounding. Local groundwater is used primarily for dust suppression, construction work, underground mining operations and in the Backfill Plant. Water supply facilities include:  Saline Wellfield, comprising several bores which intersect the Arcoona Quartzite aquifer (Figure 3-2);  Production bore LP02, located on the north side of the TSF producing from the TSF seepage mound in the Andamooka Limestone aquifer (Figure 3-2). 3.1.2 Purpose  Monitor abstraction rates from the TSF mound and saltwater wellfield and analyse patterns of saltwater use.  Maintain an understanding of the mine water balance through measurement, derivation or estimation of key parameters.  Estimate groundwater discharge to the mine workings. 3.1.3 Deliverable(s)  Review abstraction rates and trends and assess with respect to groundwater levels.  Define and map the mine water balance.  Estimate the degree of groundwater discharge to the mine. 3.1.4 Method Average daily production from production bore LP02 and the saltwater wellfield is monitored and recorded as the monthly average abstraction in ML/d. The mine water balance is calculated annually from a combination of measured, derived and estimated data.

GROUNDWATER MONITORING PROGRAM Page 31 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 3-1: Olympic Dam regional bore locations

Page 32 GROUNDWATER MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Figure 3-2: Olympic Dam site area bore locations

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Figure 3-3: Simplified Olympic Dam hydrogeological cross-section 3.1.5 Results/Discussion LP02 – TSF Mound Abstraction from the Andamooka Limestone aquifer using production bore LP02 averaged 0.14ML/d (Figure 3-4) from July 2010 to June 2011, compared to 0.17ML/d over the previous reporting period. In previous reporting periods, water from LP02 has not been included in the mine water balance. However, this water source has been integrated with the surface and mine saline water network, and can no longer be considered a separate water source. Saline Wellfield Saline water was abstracted from the Arcoona Quartzite throughout FY11 from the Saline Wellfield, located south of the Whenen Shaft. Some of this water from the Saline Wellfield was used in construction projects throughout the operations, whilst the remainder was discharged to the mine water disposal pond for evaporation. An average of 2.59ML/d was abstracted over the period, compared to 1.33ML/d during the previous reporting period.

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4.0

3.5

3.0

2.5

2.0

1.5 Water abstraction (ML/d) abstraction Water 1.0

0.5

0.0 Jul-10 Oct-10 Jun-11 Jan-11 Apr-11 Nov-10 Mar-11 Aug-10 Feb-11 Sep-10 Dec-10 May-11

TSF (LP02) Supply Saline Wellfield Figure 3-4: Site groundwater abstraction Groundwater Discharge to the Mine Groundwater inflow to the mine occurs at several intersections with the underground operations. Total natural inflow is estimated to be approximately 3.00ML/d, the majority entering via upcast raise bores. Additional natural inflow comes into the mine via other entry points, including downcast raise bores, exploration drill holes and shafts (Figure 3-5). The majority of the total inflow to the mine is exhausted to the surface as saline aerosols or moisture-laden air via upcast raise bores, estimated at around 2.50ML/d. Mine Water Balance The mine water balance is a summary of the volume of water going into and out of the underground mine. It includes saline water abstracted from local bores that is added to surface storages and used around site. The balance presented in Figure 3-5 is generated from a combination of measured, derived and estimated data.

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FY11 Yr Mine Water Balance Summary (ML/d)

Disposal/Losses Supply Sources 0.8 Evaporation/Misc Losses 0.0 Misc Supply 1.1 Mine Water Disposal Pond 0.0 Surface Recycled Potable 2.6 Saline Borefield 1.9 Surface 0.1 Andamooka Limestone Aquifer

2.7 . 1.6 Construction Use

Total Use Underground 5.1 5.9 Dewatering Risers 4.3 Saline Droppers 0.8 CAF Bleed

Natural Inflow 3.0 1.6 Raisebore Aerosols 0.9 Ore Moisture Underground Recycled Underground 2.5 Potable 0.3

Estimated Calculated or derived with some assumptions applied Measured value

 Note: sum of individual items may not exactly match totals due to rounding. Figure 3-5: Mine water balance summary FY11 (ML/d)

3.2 Groundwater Levels 3.2.1 Background Mine dewatering and seepage from surface facilities has resulted in altered groundwater levels in both the Andamooka Limestone and Arcoona Quartzite aquifers. Standing water levels differ between the aquifers from between 1m and 15m, with the potentiometric surface being approximately 50m below the surface when unaffected by Olympic Dam’s activities. In the centre of the mine area, groundwater is constantly being depleted in both aquifers creating a cone of depression which extends for a distance of approximately 5km in the Arcoona Quartzite aquifer and approximately the same distance to the north, south and east in the Andamooka Limestone aquifer. To the west, seepage from the TSF and old mine water pond area have created a groundwater mound which has risen to a maximum height of approximately 30m below the ground surface. The low transmissivity in the limestone aquifer, limited hydrogeological interconnection to the Arcoona Quartzite aquifer and the limited number of man-made interconnections (exploration drill holes, ventilation shafts etc.) result in the mound changing very little over extended periods of time, i.e. years. Abstraction from production bore LP02 from January 2000 has reduced the groundwater mound. Commissioning approval for TSF Cell 4 requires BHP Billiton Olympic Dam to ensure that ground water levels do not rise above 80mAHD. A contingency plan nominates remedial action that can be undertaken. The groundwater has no natural surface expression in the vicinity of the Olympic Dam Mine, and is at sufficient depth as to not adversely affect the native vegetation. 3.2.2 Purpose  Define the extent of groundwater level changes that have resulted from Olympic Dam’s activities.  Maintain groundwater levels in the tailings retention area to below a level at which native vegetation could be affected.

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3.2.3 Action Trigger A trending increase in the groundwater level that indicates that 80mAHD may be exceeded within 12 months. 3.2.4 Method Groundwater levels are monitored utilising a network of exploration and groundwater monitoring bores in both the Andamooka Limestone and Arcoona Quartzite aquifers. If for some reason a groundwater level cannot be obtained (e.g. blocked bore), the nearest suitable bore will be located and monitored if appropriate. Olympic Dam will maintain sufficient monitoring bores to satisfy the requirements of the ground water model and approval MPNR98/0034 Reg 98/2639 98/2885, 6/1/99, Condition 3. 3.2.5 Results/Discussion Andamooka Limestone Aquifer Groundwater Levels Water levels in the limestone aquifer beneath the TSF (Figure 3-6) remain stable. The extent of the area with a groundwater level above 65mAHD reduced slightly from previous years. The drawdown cone on the north side of the TSF corresponding to LP02 has reduced further as a result of reduced pumping volumes from this bore (see Section 3.1.5). Groundwater levels beneath the TSF between June 2010 and June 2011 confirm these changes (Figure 3-7 and Figure 3-8). Water levels have decreased around the Quarry, where inflow into the A North Decline has resulted in localised drawdown. The maximum groundwater level recorded below the TSF for the current reporting period was 67.26mAHD at LT50 in March 2011, 0.52m higher than the maximum during the FY10 reporting period. However this measurement is uncharacteristic of the general trend of falling water levels at LT50. Trends indicate that water levels are not expected to exceed the agreed limit (TSF Cell 4) of 20m below the ground (80mAHD) within the next 12 months. Monitoring of bore LM25, located near the Olympic Dam Desalination Plant, commenced in June 2005 and following a gradual decline has remained stable over recent years. Monitoring bore LR07, located in the Roxby Downs Township, continues to report stable groundwater levels. A slight level increase is evident at LR03, near the town water storage dams. Trends at this bore will be monitored. Water levels at LM46 (Figure 3-9), located near the mine water disposal pond to the northeast of the mine area, finished the reporting period at 61.77mAHD. This is an increase from 60.64mAHD last year. Water levels increased rapidly from September 2008, due to the increase in water volume discharged into the pond from the trial mine dewatering project. Water level has been relatively stable since but recent increases in discharge appear to be resulting in a gradual water level rise. Nearby LM43 has shown near identical water level changes.

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June 2006

June 2010 Groundwater level (mAHD) Groundwater

70

65

June 2011 60

55

50

35

Datum: GDA94 Projection: MGA94 Zone: 53

Figure 3-6: TSF area groundwater levels (mAHD) - Andamooka Limestone aquifer

GROUNDWATER MONITORING PROGRAM Page 39 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

75

70

65 AHD)

60

55 Groundwater level (m (m level Groundwater

50 LT19 LT35 LT52 LT45 LT50 LT51 LT09 LT16 LT17 LT18 45 -4000West -3000 -2000 -1000 0 1000 2000East Distance from centre of tailings (m from LT05)

Jun-06 Jun-10 Jun-11 Note  Monitoring bore locations shown in Figure 3-2 Figure 3-7: Change in groundwater elevation along an east-west cross-section from LT19 to LT18, through the centre of the TSF

75 LT06 replaced by LT45 LT05 replaced by LT50 70

65

60 LT36 replaced by LT52 LT07 replaced by LT51 55 Groundwater level(m AHD)

50

45 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05 Jun-06 Jun-07 Jun-08 Jun-09 Jun-10 Jun-11 Dec-01 Dec-02 Dec-03 Dec-04 Dec-05 Dec-06 Dec-07 Dec-08 Dec-09 Dec-10

LT05 LT06 LT07 LT16 LT18 LT19 LT36 LT45 LT50 LT51 LT52 Note  Monitoring bore locations shown in Figure 3-2 Figure 3-8: Groundwater levels for Andamooka Limestone bores in the vicinity of the TSF

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75

70 Town storage liner replaced

65

60

55 Groundwater level (m AHD) (m level Groundwater

50

45 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05 Jun-06 Jun-07 Jun-08 Jun-09 Jun-10 Jun-11 Dec-01 Dec-02 Dec-03 Dec-04 Dec-05 Dec-06 Dec-07 Dec-08 Dec-09 Dec-10 LR03 LR07 LM25 LM43 LM46 Note  Monitoring bore locations shown in Figure 3-1 and Figure 3-2 Figure 3-9: Groundwater levels for Andamooka Limestone bores in the vicinity of Roxby Downs (LR) and the Mine Water Pond (LM) Arcoona Quartzite Aquifer Groundwater Levels An aquifer drawdown pattern is apparent in the Arcoona Quartzite due to the dewatering around the mine workings. Over previous years the gradual drawdown trend that has remained more or less constant (Figure 3-10 and Figure 3-11). During the reporting period levels have continued to drop although bores closer to the current mine workings (RD115) remain stable. RD364 was destroyed as a result of mining activities during FY06 and removed from the monitoring program. RD169, located west of RD364, exhibits a similar drawdown curve and has been shown in Figure 3-10 as a replacement, with RD364 left for comparison. RD479 was destroyed in FY09 as a result of mining activities. During the reporting period a reading was not able to be determined for RD194 due to bore integrity. RD66, located west of RD194, has been shown here as a replacement. Water level at RD115 remains stable due to its proximity to the mine and consistent drawdown patterns in that area.

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60

40

20

0

-20 Groundwater level (m AHD) (m level Groundwater

-40

-60

-80 Jun-90 Jun-91 Jun-92 Jun-93 Jun-94 Jun-95 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05 Jun-06 Jun-07 Jun-08 Jun-09 Jun-10 Jun-11 RD66 RD115 RD169 RD172 RD194 RD364 RD479 Note  Monitoring bore locations shown in Figure 3-2 Figure 3-10: Groundwater levels for exploration drill holes in the vicinity of the underground mine

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June 2006

June 2010

Groundwater level (mAHD) Groundwater

60

40

20 June 2011 0

-20

-40

-60

-80 Datum: GDA94 Projection: MGA94 Zone: 53

Figure 3-11: Mine area groundwater levels (mAHD) - Arcoona Quartzite aquifer

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3.3 Groundwater Quality 3.3.1 Background Groundwater in the vicinity of the operation contains water of poor quality and, as defined by ANZECC (2000), is not suitable for supporting the environmental value categories (aquatic ecosystems; recreation and aesthetics; drinking supply; primary industry). Local groundwater is also unsuitable for ore processing at Olympic Dam. 3.3.2 Purpose  Monitor groundwater quality in the vicinity of the operations.  Quantify any possible impacts of seepage. 3.3.3 Deliverable(s) Review trends and make comparisons to ANZECC criteria. 3.3.4 Method Aquifer specific monitoring bores are pumped or bailed in order to obtain a representative groundwater sample for quality analysis. The samples are analysed for the following analytes:  TDS, pH, calcium, chloride, copper, iron, manganese, sulphate and uranium.  In addition, samples will be analysed for the following radionuclides:  238U, 226Ra, 230Th, 210Pb and 210Po If for some reason a groundwater sample cannot be obtained (e.g. blocked bore), the nearest suitable bore will be located and sampled if appropriate. 3.3.5 Results/Discussion Groundwater samples were collected and subsequent analytical chemistry data was obtained for 17 groundwater monitoring bore locations in May 2011. Groundwater summary data is shown in Table 3-1. Monitoring bores sampled in May 2011 varied slightly from those detailed in BHP Billiton Olympic Dam (2010c) due to access restrictions or loss/abandonment of bores. These variations are summarised below:  Bore LR6 was sampled instead of LR7 due to issues with high silt levels;  Bore LT21 was sampled instead of LT29 to provide a more even spacing in sampling locations;  Bore LT25 was included in the 2011 sampling event and is located in close proximity to the southwest corner of Evaporation Pond 2;  Bore LT26 was abandoned and backfilled during the Evaporation Pond 1 wall raise;  Bore LT51 was not sampled as the PVC casing in the bore has been damaged likely by construction activities in the area; and,  Bore LT61 was sampled instead of LT60 due to assess restrictions. In the majority of bores, the salinity has remained relatively stable and within the range that could be expected for natural variation within the aquifer. The exceptions were bore LT17, which has risen from 34,000mg/L in the previous reporting period to 54,000mg/L; and, bore LM46 which has fallen from 65,000mg/L to 49,000mg/L in the current reporting period. In the majority of bores, uranium concentrations have remained relatively stable since the previous reporting period. The highest uranium concentration in the 2011 monitoring event was from bore LM46, located adjacent to the mine water pond,

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northeast of the mine (0.53mg/L), and is slightly higher than when sampled in 2010 (0.37mg/L). The uranium concentration recorded in 2011 remains less than that recorded in 2009 (0.71mg/L). Uranium concentrations of 0.48mg/L were recorded from bore LT25 in 2011. This bore is located at the southwest corner of Evaporation Pond 2. Bore LT25 was sampled for the first time in 2011 and will be included in future monitoring to confirm the elevated uranium concentration. The reported uranium concentrations in 2011 are lower than the adopted ANZECC (2000) guidelines for livestock consumption of 0.2 mg/L except at LM46 (0.53mg/L), LT25 (0.48mg/L and LT15 (0.48mg/L). The depth (approximately 40m – 50m below ground level) and the high salinity (>19,000mg/L TDS) of the local groundwater will restrict the likelihood that it would be consumed in any significant quantities, thus not posing a health hazard to people or fauna. The groundwater monitoring program continues to define the impacts of seepage in a clear and repeatable manner. The soil cover and underlying limestone rock mass continues to effectively attenuate elements present in seepage from the TSF. All analytical results are shown in Table 3-1 below. Table 3-1: Groundwater chemistry data for bores located in the vicinity of Olympic Dam

Cu U Mn Chloride SO Ca Fe pH TDS Analyte 4 (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Drinking Limit 2.00 0.02 0.50 N/A 500 N/A N/A N/A N/A (ADWG 2004) Livestock (Sheep) Limit 0.50 0.20 N/A N/A 1000 N/A N/A N/A 5000 (ANZECC, 2000)

Bore Date LM43 May 2011 <0.005 0.063 1.1 21000 2000 1300 1.6 6.9 39000 LM46 May 2011 <0.005 0.532 <0.025 28000 2100 1300 <0.25 7.3 49000 LR6 May 2011 <0.005 0.016 2.0 12000 1500 980 0.60 7.2 26000 LR8 May 2011 <0.005 0.020 0.47 15000 1500 1100 1.8 7.4 31000 LR9 May 2011 <0.005 0.031 2.3 14000 1900 1100 4.6 6.8 28000 LT1 May 2011 <0.005 0.106 0.58 12000 1600 880 2.2 6.9 24000 LT2 May 2011 <0.005 0.047 1.5 12000 1600 1000 7.5 6.5 26000 LT15 May 2011 <0.005 0.479 <0.025 11000 1900 1100 <0.25 6.8 34000 LT17 May 2011 0.009 0.069 <0.025 23000 1900 1300 <0.25 7.6 37000 LT19 May 2011 <0.005 0.025 0.54 11000 1600 960 1.2 7.2 24000 LT21 May 2011 <0.005 0.138 0.31 12000 1800 950 0.07 6.8 26000 LT22 May 2011 <0.005 0.072 <0.025 4500 1500 730 <0.25 7.4 19000 LT25 May 2011 <0.005 0.484 7.9 12000 2200 850 34 6.4 27000 LT34 May 2011 <0.005 0.045 0.72 13000 1900 980 1.6 6.9 26000 LT35 May 2011 <0.005 0.046 0.75 11000 1800 990 2.0 6.8 24000 LT39 May 2011 <0.005 0.033 0.86 14000 1700 1000 3.0 7.1 26000 LT61 May 2011 <0.005 0.017 0.53 13000 1700 1000 2.3 7.2 27000

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3.4 Use of Mine Water for Dust Suppression 3.4.1 Background Water obtained from the mine as a result of mine dewatering or collected from vent fan outflow is used around site for watering of roads for the purpose of dust suppression. Local groundwater is of very low quality and is unsuitable for other industrial or environmental uses. Radiation levels in mine water used for road watering are monitored annually to ensure they remain within acceptable levels. Table 3-2: Upper limits for radionuclide content in dust suppression water

Upper Limit Value Radionuclide (Bq/L) 238U 50 226Ra 5 3.4.2 Purpose Monitor sources of mine water used for road watering. Ensure negligible long term effects of the release of mine water. 3.4.3 Deliverable(s)  Ensure water used for dust suppression is within acceptable radiation levels as defined in Table 3-2.  Review results and provide for increased monitoring frequency where readings approach the action trigger level. 3.4.4 Action Trigger  A radiation level obtained from sampled mine water that approaches the upper limits of the acceptable radiation level.  A trend indicating that the radiation level upper limit will be exceeded within a period of 12 months. 3.4.5 Method Sources of mine water, including raise bore ponds and storage dams, are sampled at least once per year and checked for radiation levels. Where readings for a source are near to or above the action trigger, additional monitoring will be conducted on a more frequent basis. Use of mine water from a source found to exceed the limit will cease until the radiation level has been found to have dropped below that limit. 3.4.6 Results/Discussion Samples from water used for dust suppression were collected during May 2011 and results are shown in Table 3-3, Figure 3-12 and Figure 3-13. 238U and 226Ra activity levels for all samples were well below the respective upper limits and are consistent with previously recorded values.

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Table 3-3: Radionuclide analysis for dust suppression water

238 U 230Th 226Ra 210Pb 210Po Radionuclide (Bq/L) (Bq/L) (Bq/L) (Bq/L) (Bq/L) Sample ID Date DESAL PLANT May 2011 0.08 0.010 2.10 0.002 0.008 A-BLOCK May 2011 0.63 0.120 2.20 0.000 0.021 D-BLOCK May 2011 10.700.060 1.00 0.122 0.110 F-BLOCK May 2011 15.700.013 1.10 0.007 0.017 TURKEY NEST May 2011 0.82 0.000 0.59 0.000 0.000

50 Upper limit

40

30 U (Bq/L) 238

20 Activity level level Activity

10

0 Desal Dam A Block D Block F Block Sample site

Figure 3-12: Mine water sample 238U levels and upper limit, FY11

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5.0 Upper limit

4.0

3.0 Ra (Bq/L) Ra 226

2.0 Activity level level Activity

1.0

0.0 Desal Dam A Block D Block F Block Sample site

Figure 3-13: Mine water sample 226Ra levels and upper limit, FY11

3.5 Conclusion  Average abstraction rates from the TSF mound (LP02) and Saline Wellfield were 0.14ML/d and 2.59ML/d respectively.  Peak groundwater level beneath the TSF for this reporting period was approximately 67mAHD. Levels are not expected to exceed the limit of 80mAHD (20m below the ground) within the next 12 months.  The drawdown cone in the Arcoona Quartzite aquifer has changed slightly although water level in bores closer to the current mine workings remain stable.  Slightly elevated concentrations of uranium continue to be detected in the groundwater beneath the mine water disposal pond and old mine water disposal pond. Measured values do not pose a health hazard due to the low concentrations and the salinity of the water, which restrict its use for human or animal consumption.  Radiation activity levels for dust suppression water were found to be consistent with those measured in FY10 and were all below the upper limit values.

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4 GREAT ARTESIAN BASIN (GAB) WATER MONITORING PROGRAM

Water used at Olympic Dam and the Roxby Downs township is pumped from two wellfields located within the GAB. A summary and interpretation of data related to the impact of Olympic Dam on the GAB is the subject of a separate annual GAB Wellfields Report (BHP Billiton Olympic Dam 2011a), produced in accordance with the requirements of the Roxby Downs (Indenture Ratification) Act 1982. The Wellfields Report 1 July 2010 – 30 June 2011 is attached to this document and the content is not repeated in this section. The requirements of Olympic Dam in regard to management of GAB groundwater supply issues are outlined in the Monitoring Program – Great Artesian Basin (GAB) FY11 (BHP Billiton Olympic Dam 2010d).

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5 FAUNA MONITORING PROGRAM

5.1 Avifauna 5.1.1 Background Previous monitoring and research has indicated that several species or species groups of birds may be used as indicators of impacts associated with the mine and processing operation. It has been demonstrated that Crested Bellbirds and mixed feeding flocks of insectivorous birds decrease in abundance in close proximity to the operation (Read et al. 2000, Read et al. 2005). Past research has also determined a group of bird species that have been seen to benefit from the presence of operations, known as ‘disturbance’ species. The presence/absence of these bioindicators and species richness of ‘non- disturbance’ bird species at different site types are surveyed. 5.1.2 Purpose Utilise avifauna as an indicator of environmental change. 5.1.3 Deliverable(s) Map the impact footprint of Olympic Dam’s activities on abundance of Crested Bellbirds and mixed feeding flocks of insectivorous birds, and species richness of ‘non- disturbance’ species, for the Environmental Management and Monitoring Report. 5.1.4 Method A total of 48 sites are surveyed in April, July and October for all bird species present. Sites are separated into three main areas defined by potential impact: mine (within 500m of mine and process); intermediate (1km from mine and process); and control (> 4km from mine and process) (Figure 8-1). Each site is located on a dune containing a patch of mulga woodland and other shrub species. Each site covers an area 200m by 200m. During each survey period all sites are surveyed for a period of 10 minutes. During this time all birds, seen and heard, are recorded. Surveys are conducted in the morning, within four hours of sunrise, allowing approximately six sites to be surveyed each day. Avifauna survey data are used to determine the presence/absence of bioindicator species and the species richness of ‘non-disturbance’ bird species at different site types. 5.1.5 Results/Discussion The overall abundance of Crested Bellbirds and mixed feeding flocks within mine, intermediate and control zones remained similar to previous years (Figure 5-1 and Figure 5-2). There was a significant difference in abundance of Crested Bellbirds recorded at mine, intermediate and control sites (Kruskal-Wallis non-parametric test, 2 = 20.34 and P = <0.001). Numbers of Crested Bellbirds were higher at intermediate sites than mine sites and higher at control sites than intermediate sites (Figure 5-1). This trend is consistent with previous reporting periods. No significant difference was detected between abundances of insectivorous mixed feeding flocks at sites distant from the operations and those within the immediate vicinity of the operations (Kruskal-Wallis non-parametric test, 2 = 4.01 and P = 0.135), however graphically the trend shows a lower number closer to operations (Figure 5-2).

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3.5

3.0

2.5

2.0

1.5

Mean number of CBB (+SE) CBB of number Mean 1.0

0.5

0.0 Mine (n=15) Intermediate (n=17) Control (n=17)

FY00 FY01 FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 FY10 FY11

Figure 5-1: Abundance of Crested Bellbirds (CBB) in each of the monitoring zones (± 1 standard error).

8.0

7.0

6.0

5.0

4.0

3.0 Mean number of IFF (+SE) (+SE) of IFF number Mean

2.0

1.0

0.0 Mine (n=15) Intermediate (n=17) Control (n=17)

FY00 FY01 FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 FY10 FY11

Figure 5-2: Abundance of insectivorous feeding flock (IFF) species in each of the monitoring zones (± 1 standard error). An impact footprint of the bioindicators, Crested Bellbirds (CBB), insectivorous feeding flocks (IFF) and the species richness of ‘non-disturbance’ bird species, suggests that the impacts of the operations on avifauna are limited to the immediate vicinity of the mine and processing plant and surrounding areas within the Special Mining Lease (Figure 5-3). The impact footprint for the current reporting period appears slightly larger than the FY10 mapped impact footprint (Figure 5-3).

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Figure 5-3: Impact footprint of the bioindicator bird species during FY10 and FY11 periods

5.2 Small Mammals and Reptiles 5.2.1 Background Small mammals and reptiles are used as biological indicators of the condition of the environment, both adjacent to, and at a distance from, the mine and processing plant. These studies allow examination of the nature and extent of impacts. Geckos, due to their sensitivity to air pollution, are the most suitable local reptiles for use as bioindicators (Read 1998). Geckos have large eyes and soft skin, making them susceptible to contaminants. Geckos are also ideal bioindicators as their fecundity is readily measured, therefore any declines in fecundity as a result of operational activities can be assessed. Ctenotus skink captures generally exceed Ctenophorus dragon captures in unimpacted sites (Read et al. 2005). Similarly, native rodent captures (Pseudomys sp., Leggadina forresti, and Notomys alexis) generally exceed captures of House Mice (Mus domesticus) in unimpacted sites (Read et al. 2005). 5.2.2 Purpose Utilise small mammals and reptiles as an indicator of environmental change. 5.2.3 Deliverable(s) Map the impact footprint of Olympic Dam’s activities on the fecundity of geckos, Ctenotus/Ctenophorus ratios and feral/native mouse ratios for the Environmental Management and Monitoring Report. 5.2.4 Method Reptile abundance, mammal abundance, and abundance, age, and fecundity of geckos are recorded annually during a trapping session each December. A total of 14 sites are monitored with sites located in areas as defined by possible impacts. These include sites located near the smelter and ventilation shafts, and also intermediate and

Page 52 FAUNA MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT control sites. The regional locations of the fauna monitoring sites are shown in Figure 8-2. Animals are captured using pitfall traps. Each trapping site consists of 13 pitfall traps arranged in a cross formation. The pits are five metres apart and, when opened, are linked by a fly mesh fence. Between the annual sampling periods the fence is removed and pits are left in place covered with tightly fitting caps. 5.2.5 Results/Discussion The FY11 results showed an increased impact footprint compared with the FY10 period (Figure 5-4). Sites closest to the operation generally scored lower than those at distance, which may indicate evidence of impacts from mining and processing operations. However scores for FY11 were biased by the high number of introduced house mice in the region following good conditions brought on by an extended period of above average rainfall. This may explain the expanded impact footprint during FY11. Gecko fecundity scores were variable, although sites within the raisebore saline exhaust area all scored 0%. While fecundity at sites near the smelter were higher, very few geckos were captured there. Captures at intermediate and control sites were generally higher. Results suggest some impact from the operation may be present.

Figure 5-4: Impact footprint of reptiles and small mammals during FY10 and FY11 periods

5.3 Amphibians 5.3.1 Background The Trilling Frog (Neobatrachus centralis) is a medium sized burrowing frog that is common in the Olympic Dam region. Typically large numbers of this species emerge en masse following rainfall events of greater than 50mm during the warmer months. Levels of limb abnormalities in frogs are investigated from individuals captured close to the mine and metallurgical plant and at control sites distant from Olympic Dam. 5.3.2 Purpose Utilise amphibians as indicators of environmental change.

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5.3.3 Deliverable(s) Establish if there is a difference in the incidence of abnormality in the most recent cohort of Trilling Frogs in areas close to, and distant from, operations. 5.3.4 Method Adult frogs are opportunistically sampled from sites close to (within 1km), and distant from (over 4km), the mine and processing plant. Frogs are collected from the road, or from areas surrounding and within bodies of water immediately following significant rainfall. Snout-vent length and sex is determined and recorded for all frogs captured. Juvenile frog offspring resulting from the breeding event triggered by significant rainfall are collected over following weeks as they emerge from ephemeral water bodies. Each frog is also carefully scrutinised for deformities before being released. Detailed methods are described in Read and Tyler (1990). 5.3.5 Results/Discussion As reported in the FY10 EMMR, on the 9th of April 2010 over 80mm of rain was received. Following the rainfall frogs emerged, however the moderate temperatures during that period meant that the frogs did not emerge en masse. As a result of this, ideal sample sizes of frogs were not able to be collected. Adult frogs were collected directly following the rainfall event, with 100 being collected from close proximity to the operation and 212 collected distant to the operation. Several weeks after the rain 440 metamorphlings were collected close to the operation and 192 were collected away from the operation. Abnormalities were detected in both adult frogs and metamorphlings. Further testing is required to determine if abnormalities were due to mutations or injury. This is a highly specialised skill and there has been some difficulty contracting a suitably skilled person to complete the work. Frogs with abnormalities are currently being examined and results will be available in FY12.

5.4 Feral and Abundant Species 5.4.1 Background Kangaroos are native and commonly recorded medium sized mammals of the region, however due to artificial water bodies and the lack of domestic grazing on the SML their abundance is often altered. Both kangaroo and rabbit numbers directly affect the condition of the vegetation on the mine and municipal leases. These herbivores also affect the success of rehabilitation measures and amenity plantings within the mine and municipal leases. Similarly, cat and fox numbers have the potential to increase in response to land management practices and impact on native vertebrate populations. Therefore, these medium sized mammal species can potentially have an impact on the ecology of the region. For this reason medium sized mammal numbers are monitored regularly and controlled when necessary. 5.4.2 Purpose Monitor and control feral and abundant species within the Special Mining and Municipal Leases. 5.4.3 Deliverable(s)  Provide a quantitative assessment of the abundance of specific feral and abundant species in the operations area.  Identify if measures are required to control feral or abundant species in the operations area.

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5.4.4 Method The abundance of kangaroos, rabbits, cats and foxes is determined every three months along three spotlight transects of approximately 20km in length (Figure 8-3). Fixed transects are located in the dune country north of the operation, south of the operation around the town lease boundary, and east of the operation on Andamooka Station. All transects are located inside the dog fence. Cattle grazing occurs on Andamooka Station but on all other transects cattle have been removed for over 15 years. Kangaroo harvesting is undertaken on Andamooka Station. A permanent water source is available on the north transect while water is available irregularly in other transects. The south transect is located among closely spaced dunes, while the other two transects are located in an area of widely spaced dunes. As a result of the varying transect characteristics, the number of kangaroos in the north transect are often observed to be at levels significantly higher than those recorded in the other transects. Cat and fox control is conducted in and around the operations and on the more remote areas of the SML on an opportunistic basis, through trapping and baiting. Stomach content analysis is conducted and reported for all cats and foxes collected. Populations of feral and abundant mammals (rabbits and kangaroos) are largely dependent on climatic conditions and fluctuate accordingly. Furthermore, these populations are largely independent of mining and processing operations. Control of these groups is also considered impractical on a large scale. House mice are not controlled. As the operation is located in a pastoral area, they are not considered to be a significant pest species. 5.4.5 Results/Discussion Summaries of monitoring results for rabbits, kangaroos, foxes and cats are shown in Table 5-1. As expected, following the above average rainfall during FY10 and FY11, local rabbit populations have risen over the monitoring period, more than doubling along some transects (Figure 5-5). However, rabbit densities for the FY11 reporting period remained lower than the long-term mean on all transects. The number of cats observed during FY11 was also above FY10 records. On the mine transect, the average abundance of cats observed during FY11 is above the long term mean. Other transects remain below the long term mean (Figure 5-6). The higher number of cats is likely a result of an increase in food availability (small mammals and reptiles) following the above average rainfall during previous years. No foxes were observed during FY11 monitoring (Figure 5-7). The average abundance of kangaroos was lower than that recorded during FY10 on all transects (Figure 5-8). The same trend was noticed when compared to the long term mean. This is likely due to the dispersal of kangaroos given the favourable conditions.

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Table 5-1: Summary of rabbit, cat, fox and kangaroo numbers (per square kilometre), showing historical abundance, FY10 and FY11

Long-term Long-term Long-term FY10 FY11 Species Transect min max mean mean mean

Rabbits Town 0 220 49.76 22.26 43.11 Mine 0 586 81.39 11.14 32.37 Andamooka 4.10 83.92 31.23 8.67 24.02 Cats Town 0 3.10 0.56 0 0.25 Mine 0 4.70 0.64 0 1.28 Andamooka 0 2.05 0.15 0 0 Foxes Town 0 3.60 0.35 0 0 Mine 0 3.90 0.32 0 0 Andamooka 0 0.76 0.06 0 0 Kangaroos Town 0 17.60 3.31 1.29 0.97 Mine 0 35.59 11.30 4.69 3.70 Andamooka 0 28.67 5.51 3.00 2.42  Note: the Town and Mine transects were established in 1989 and the Andamooka transect was established in 2002.

600

500

400

300 Rabbits per km² Rabbits per 200

100

0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Town Mine Andamooka

Figure 5-5: Three sampling sessions moving average (per km2) for rabbit abundance at three transects in the Olympic Dam region

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4

3

2 Cats per km²

1

0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Town Mine Andamooka

Figure 5-6: Three sampling sessions moving average (per km2) for cat abundance at three transects in the Olympic Dam region

3

2 2 Foxes per km per Foxes 1

0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Town Mine Andamooka

Figure 5-7: Three sampling sessions moving average (per km2) for fox abundance at three transects in the Olympic Dam region

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35

30

25

20

15 Kangaroos per km² per Kangaroos

10

5

0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Town Mine Andamooka

Figure 5-8: Three sampling sessions moving average (per km2) for kangaroo abundance at three transects in the Olympic Dam region A total of 54 cats and 29 foxes were shot, trapped or tracked and caught within the Olympic Dam region during FY11 and 66 stomachs were examined for items of prey. Stomach analysis of these animals found that 190 individual items of prey were evident (Table 5-2). A majority of the prey items were mammals with one species of bird also identified. Five fauna species found in cat stomachs were identified, there were eight rabbits, 43 house mice, 46 hopping mice, five Plains Rats and two Button Quails. Also present were 85 unidentified small mammal specimens. The data recorded during FY11 indicates that native fauna species continue to be preyed upon by feral cats and foxes in the region. Table 5-2: Cat stomach analysis results

Prey groups No. of stomachs Total individuals containing prey items taken

Invertebrates 11 Mammals Rabbit 8 8 House mouse 19 43 Hopping Mouse (Notomys alexis) 24 46 Plains Rat (Pseudomys australis). 3 5 Unidentified Small Mammal 34 85 Birds Little Button Quail (Turnix velox) 22 Total Prey Items 190

5.5 At-risk Species – Category 1a A number of at-risk species have been recorded or regularly occur within the project area. At-risk species have been classified by BHP Billiton Olympic Dam into three main

Page 58 FAUNA MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT categories – Category 1a, Category 1b and Category 2. Appendix 2 contains a flow chart detailing how priority species are identified. All Category 1a species are considered ‘at-risk’ as their population as a whole is largely restricted to the impact area and therefore the species has a higher risk of being impacted. These species are all formally listed species under state, national and international conservation listings. The degree of at-risk species monitoring depends largely on the category under which they fall. Monitoring of Category 1a is intensive in comparison to Category 1b and Category 2 (Section 2.6), which reflects the species’ reliance on the potential impact area. A list of all Category 1a fauna occurring in the impact zone is included in Appendix 3. This includes invertebrates largely restricted to the GAB springs of the Lake Eyre South region in the vicinity of the wellfields. 5.5.1 Background A diverse endemic invertebrate fauna occurs in springs associated with the GAB in South Australia and Queensland. As GAB springs are small aquatic habitats, widely separated in an arid environment, it has been found that localised groups of GAB springs support their own specific types of endemic invertebrates (Ponder 1986). GAB springs in the Lake Eyre South region support at least six species of Hydrobiid in two genera (Trochidrobia and Fonscochlea), a phreatoicid isopod (Phreatomerus latipes), an ostracod (Ngarawa dirga) and an amphipod (Afrochiltonia sp.). All these species are aquatic and are currently only known to occur in GAB springs between Marree and Oodnadatta (the only known exception is a species of Hydrobiid recorded in low abundance from Coward Springs Railway Bore) (Ponder et al. 1989). All species of Hydrobiid present in these springs are currently recognised as internationally significant (Baillie and Goombridge 1996). The persistence of GAB spring aquatic invertebrates is intimately linked to the availability of free flowing water at GAB springs. While the aquatic populations have been exposed to natural spring processes of emergence and decline over considerable time periods, it is likely that populations would be susceptible to any accelerated spring decline over comparatively short time periods, which may be caused by excessive drawdown. 5.5.2 Purpose Qualify the level of population change that may be attributed to water extraction from the wellfields. 5.5.3 Action Trigger Evidence that indicates unacceptable harm or detriment to at-risk species or ecological communities which can be attributed to drawdown. 5.5.4 Method Spring groups within the potential impact zones of the GAB are visited triennially and sampled for the presence/absence of endemic invertebrate species. Sampling is conducted in the middle year of the Environmental Management Manual (EMM) triennium, with sorting analysis completed during the final year of the EMM triennium. Previous research has shown that presence/absence data provides the same level of information as measures of abundance (Tyre and Possingham 2001). Therefore a large number of springs are visited and sampled for presence/absence, as opposed to visiting a small number of springs and providing a quantitative analysis. This enables a broader impression of current population status to be gained. Substrate samples are taken at each of the designated springs using a standardised scoop and tray, and analysed for presence/absence of key fauna species/groups.

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Time series data are summarised and inspected for long term trends. Baseline data consists of samples collected during 1995/1996 with further additional sampling conducted during 1999, 2000, 2002-2005. Monitoring sites are grouped in zones for analysis based on predicted levels of impact listed in Appendix 5 of the Monitoring Program – Great Artesian Basin (OLYMPIC DAM Document No: 2789). 5.5.5 Results/Discussion Field surveys and sample collection were completed during FY09 with laboratory analysis completed in FY10. Data analysis was not completed before the deadline for this report and therefore will be reported on at a later date.

5.6 At-risk Species – Category 1b and 2 5.6.1 Background Category 1b comprises species for which important populations may be critically reliant on areas impacted by the operation. Category 1b species are those with local sedentary populations that are exposed to impact from the operations and have limited alternate habitat in the region. Also included are highly mobile species that travel in large numbers and are attracted to hazardous areas within the operation. Category 2 includes at-risk species whose population as a whole is not critically reliant on the area of impact, i.e. only individuals of a species are likely to be impacted. Category 2 species are those that are included under state, national and international conservation listings and other species which have been recorded in the area that BHP Billiton Olympic Dam are not legally required to manage but which may also be adversely impacted by operations (includes some resident un-listed species) (Appendix 2). Species listed as migratory under the Environment Protection and Biodiversity Conservation Act 1999 are only included under Category 2 if they both occur within the impact zone and are also likely to be impacted by the operation. The degree of at-risk species monitoring depends largely on the category under which they fall. Category 1b and Category 2 at-risk species are recorded in the region but are not considered to be confined or dependent on this area. Consequently, there is no specific management activity which applies to Category 1b and Category 2 at-risk species, unless a risk-based assessment identifies action by BHP Billiton Olympic Dam as necessary (i.e. Category 1b and Category 2 species affected by the TRS). If the understanding of a species risk category changes, Category 1b or Category 2 species may be elevated to Category 1a, with a subsequent increase in monitoring effort. Forty- two species of bird, nine species of mammal and one reptile species have been identified in the Olympic Dam and wellfields region under Categories 1b and 2 (Appendix 3). 5.6.2 Purpose Determine if there is a requirement to implement any management activity for the protection of Category 1b or Category 2 species in the vicinity of the operations. 5.6.3 Deliverable(s)  Provide a qualitative assessment of the presence of Category 1b and 2 at-risk species in the SML and wellfields region; and  Identify if management activity is required for Category 2 at-risk species through a risk-based assessment (i.e. bird species on the TRS). 5.6.4 Method Species lists are compiled monthly for all birds sighted in:  The SML;

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 The surrounding pastoral stations; and,  The wellfields region. Category 1b and Category 2 at-risk species of mammals are observed through the annual field sampling associated with the small mammal and reptile monitoring (Section 2.2), regular surveys of local water bird populations (Section 2.6), avifauna monitoring (Section 2.1) and through opportunistic sampling. 5.6.5 Results/Discussion Twenty species of Category 1b and 2 birds and five species of mammal were recorded in the Olympic Dam SML, wider region and the wellfields during the reporting period (Table 5-3). Twelve Plains Rats, one Banded Stilt and two Musk Ducks were recorded dead following interactions with the Tailings Retention System (TRS) during the reporting period. Management of deaths associated with the TRS is discussed in Section 5.7. No management activities were required for Category 1b and 2 species during FY11. Table 5-3: Category 1b &2 species recorded in the Olympic Dam and wellfields region for FY11

Species Jul Oct Jan Jan Apr Feb Feb Mar Jun Jun Sep Dec Nov Nov Aug Aug May

Birds Australasian Shoveler   Australian Bustard   Banded Stilt            Blue-billed Duck   Brolga  Caspian Tern  Cattle Egret  Common Greenshank  Common Sandpiper  Elegant Parrot   Flock Bronzewing   Fork-tailed Swift  Great-crested Grebe   Great Egret  Musk Duck           Peregrine Falcon  Plains Wanderer  Red-necked Stint   Sharp-tailed Sandpiper      Thick-billed Grasswren   Mammals Burrowing Bettong             Greater Bilby             Greater Stick Nest Rat            

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Species Jul Oct Jan Jan Apr Feb Feb Mar Jun Sep Dec Nov Nov Aug Aug May

Plains Rat             Western-barred             Bandicoot

5.7 Fauna Losses 5.7.1 Background Priority species of water birds have been recorded in the Olympic Dam area. Evaporation ponds and tailings storage facilities (which together comprise the Tailings Retention System – TRS) are sometimes visited by fauna which can result in fauna deaths (particularly birds and kangaroos). There is the potential for at-risk species of birds to visit these waste liquor storages. Several engineering controls have been designed and implemented to minimise these impacts. 5.7.2 Purpose Assess the performance of control measures that aim to minimise the risk of Category 1b and Category 2 fauna species from entering waste process liquor ponds. 5.7.3 Deliverable(s)  Provide an assessment of fauna activity and losses within the TRS; and,  Provide a quantitative assessment of the numbers of waterfowl using local non- toxic water bodies. 5.7.4 Method Standardised monitoring of the Evaporation Ponds and Tailings Storage Facilities is conducted on a weekly basis (each Wednesday) to detect the presence of any fauna (dead or alive) within the system. This monitoring is conducted by trained staff members and any fauna carcasses present are removed. This data is not a quantitative number of fauna using or dying within the system, rather it is used to assess trends and detect large changes in fauna activity and losses experienced at the TRS. Where appropriate, data is correlated to changes in management practices or other factors. Opportunistic observations of fauna using the TRS are also made by trained staff and technicians. Monthly bird surveys are conducted at large water bodies where water birds congregate (i.e. desalination plant, sewerage ponds, and mine water ponds) and also the TRS. This allows the local population of water birds (especially transient species) to be determined and compared with those detected at the TRS. 5.7.5 Results/Discussion Opportunistic observations of fauna within the TRS continued to be made by TRS technicians during the FY11 reporting period. Opportunistic observations were also made by Environment and other staff throughout this period. Standardised weekly monitoring was undertaken throughout the reporting period. During the FY11 period a total of 348 mortalities were recorded during standardised weekly monitoring (Figure 5-9), compared with 148 recorded in FY10 (Figure 5-10). This year was exceptional as small mammals comprised the majority of deaths (246) as opposed to birds. A majority of the small mammals that could be retrieved and identified were introduced house mice. Also observed were 12 Plains Rats and eight Spinifex Hopping Mice. The increase in numbers of small mammals recorded dead at the TRS is due to the massive increase in small mammal numbers in the region following the favourable conditions induced by prolonged above average rainfall.

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Although the Plains Rat is listed as vulnerable under state legislation the death of 12 individuals at the TRS is believed to be a reflection of the current high numbers in the area. Of the birds, Silver Gulls were the most commonly recorded mortalities with 28 deaths, followed by the Whiskered Tern (12) and Hoary-headed Grebe (10). A small number of reptiles were also recorded (two Sleepy Lizards, two dragon species, two snake species, one Central Netted Dragon, one blind snake, one Broad-banded Sand- swimmer and one Curl Snake). The numbers of live fauna observed was positively skewed by Fairy Martins nesting in the area during the first half of FY11. No Fairy Martins were found dead and they were not observed interacting with the liquor.

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Figure 5-9: Monthly summary of weekly monitoring results for FY11, showing total number of animals (birds, mammals and reptiles) recorded within the TRS

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Alive Confirmed Dead

Figure 5-10: Quarterly summary of all weekly monitoring results, showing total number of animals (birds, mammals and reptiles) recorded within the TRS All fauna observed opportunistically (i.e. outside formal monitoring sessions) during FY11 are summarised in Figure 5-11. Opportunistic observations bias towards live animals, especially large flocks, hence more live animals than dead animals are usually observed.

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0 Jul-10 Oct-10 Apr-11 Jan-11 Jun-11 Mar-11 Feb-11 Aug-10 Sep-10 Nov-10 Dec-10 May-11 Opportunistic Observations - Alive Opportunistic Observations - Confirmed Dead Figure 5-11: Monthly summary of opportunistic observation results for FY11, showing total number of animals (birds, mammals and reptiles) recorded within the TRS

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The data presented indicate the number of fauna counted and do not represent total numbers. They are presented as an index only. A number of factors must be considered when interpreting these data and refining our monitoring and data analyses:  Birds may be seen and recorded as alive on one day and subsequently may be observed as dead. The total includes both observations, leading to a possible overestimate;  Scavenging by birds of prey and corvids means that some carcasses may be removed from the system prior to an observation being made;  Carcasses floating in the liquor may sink and disappear before being recorded; and,  Some fauna species may leave the system and die elsewhere. The numbers recorded as having been killed by their interactions with the TRS represent a small proportion of those that visited. Preventing and deterring visitations by large flocks of birds, particularly Banded Stilts, remains a focus of management efforts at the TRS. The large numbers of birds recorded at local non-toxic water bodies continue to demonstrate the limited number of birds from local and nomadic bird populations that utilise the TRS (Figure 5-12).

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 Note: Observed TRS bird numbers for several months were very low (<3) and may not be visible at the scale of this graph. Figure 5-12: Monthly summary of number of water birds recorded at local non- toxic water bodies in comparison to TRS during FY11 An increase in the usage and associated deaths of fauna at the TRS was noted during 2004. This increase was reflected in much higher water bird numbers in regional clean water bodies and is thought to be largely due to increased bird traffic associated with seasonal flooding of the Lake Eyre Basin. A public disclosure about this matter was made by Olympic Dam in January 2005. The increase in observed fauna interactions prompted the commencement of a research project aimed at investigating risks to fauna resulting from interaction with the TRS. This project commenced in July 2004 and continued throughout the FY11 reporting period.

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Activities undertaken during FY11 as part of the project include:  The full time, Scientist Environment (TRS Fauna) role was maintained over the reporting period;  Assessment of the effectiveness of current and alternative control measures (including deterrent systems) continued;  Trials of sound identification software continued, to determine its efficacy at identifying waterbird species and its potential use as part of an on demand deterrent system. The SoundID option is currently being progressed with the option to develop a Marine Radar system at a later date. Assessments suggest that SoundID has the potential to be equally or more effective than a marine radar system;  Regular meetings of the TRS fauna working group continued;  Collaborative research between BHP Billiton Olympic Dam and Deakin University continued. This is an approximately $5 million dollar project conducted over four years. The research is focusing on two particular areas:  Using captive birds to determine the most effective light wavelengths and flicker rates for aversive stimuli in an effort to develop a more effective deterrent. The critical flicker fusion rate has been determined for a number of wavelengths for a number of species as has their spectral sensitivities; and,  Better understanding bird movements between regional water bodies and what effects these movements e.g. night time light levels and weather patterns in different regions. In depth movement data has been gathered from 38 Pacific Black Ducks using satellite transmitters. This has revealed useful patterns of day/night movement and movement in response to rain etc. The project is now seeking approval to begin tracking and gathering data from Black Swans.  Trials designed to determine the durability of HDPE netting and bird balls at the TRS continued. This will help determine their suitability for use in future tailings storage facilities. Future planned activities include:  Ongoing projects assessing water efficiency onsite, to reduce volume of liquor on the Tailings Storage Facility (TSF);  Continued collaboration with Olympic Dam Projects section regarding future infrastructure as part of the expansion project;  A trial of netting materials;  Development of the SoundID system; and,  Consideration of the use of offsets for the current impacts at the TRS.

5.8 Conclusion  Avifauna indicators show that the operation appears to have measurable impacts in close proximity to the operation. The extent appears similar to the previous year.  Gecko gravidity, reptile and small mammal indicators show that the operation appears to have observed impacts when in close proximity to the operation. High numbers of the introduced House Mouse influenced scores from small mammal and reptile monitoring.  Kangaroo, rabbit and fox numbers were lower than the long term mean on all transects. Cat numbers rose above the long term mean on the mine transect. Rabbit numbers were nearly double the previous reporting period due to above average rainfall over FY10 and FY11.

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 GAB spring invertebrate data analysis has not yet been completed and will be reported on at a later date.  Several Category 2 listed species were recorded in the Olympic Dam SML area and the wellfields region. Three of the species recorded were within the TRS system and several other waterbird species have the potential to visit this area.  There were 348 fauna mortalities recorded during weekly monitoring at the TRS in FY11, which compares to 148 for the previous reporting period. This increase was largely due to introduced house mice. The TRS Fauna project continued in FY11.

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6 FLORA MONITORING PROGRAM

6.1 Emission Impacts to Vegetation 6.1.1 Background Atmospheric emissions from the Olympic Dam mine and processing operation include:  dust from quarrying, mining and milling operations, and vehicle use of tracks.  saline aerosols from raise bore ventilation shaft exhausts, and mist with solvents from the tailings residue dams and evaporation ponds,the tailings retention system (TRS).

 gaseous and acidic emissions, primarily sulphur dioxide (SO2), other sulphur oxide gasses, hydrogen fluoride, and heavy metal compounds from the smelter and sulphur and sulphuric acid production plants. The largest volume of dust is generated from the Backfill Quarry northwest of the mine operation and from vehicles conveying quarried material to and from the Backfill plant and stockpiles. Dust is readily dispersed by wind. The mine ventilation shafts (raise bores), used for circulating fresh air underground, intercept two saline aquifers. The water from these aquifers flows into the shafts and is carried to the surface by the upcast ventilation (upcast raise bores) in the form of a saline aerosol. The aerosol is released into the environment where it accumulates on vegetation and in the soil. Parts of the copper smelting process (flash furnace and anode furnaces) result in the generation of SO2 and other compounds including copper compounds. The emission of SO2 from the process plant is controlled through the collection of SO2 rich off-gases for conversion to sulphuric acid at the Acid Plant. During normal operation, the residual emissions are vented to the atmosphere via the Acid Plant Tails Stack. Fugitive emissions captured by the hygiene ventilation system are vented via the Main Smelter Stack. These low level emissions are continuous. High concentration SO2 emissions can occur if the off-take gas cleaning system fails. The management of SO2 is regulated according to the Olympic Dam EPA Licence 1301. These emissions have the potential to damage vegetation in the areas surrounding the operation. However, many control measures have been employed to reduce emissions and hence the impact of the operations. These strategies include improved environmental engineering and process control. Research to date (Griffin and Dunlop, 2007 and 2007a) suggests that indicator species sensitive to atmospheric emissions are Acacia ligulata and Dodonaea viscosa. The symptoms displayed by these species are used as indicators of Olympic Dam’s impact. The symptoms may reflect a number of cumulative impacts from aerosols and from solutes in the soils and systemically in the plants. Sampling has demonstrated a correlation between the number of symptoms present on both species at a site and the levels of copper (Cu) and sodium (Na) combined in the foliage of these plants. These two contaminants each reflect different sources of emissions (the Main Smelter Stack for Cu, and raise bores for Na) and their different spatial distributions. The two plant species, A. ligulata and D. viscosa, each respond differently to the contaminant levels. The combined symptom count provides a simple and robust measure that is demonstrably linked to emissions levels.

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6.1.2 Purpose To define the impact footprint of BHP Billiton Olympic Dam’s activities, if any, on vegetation and in particular the indicator species (Acacia ligulata and Dodonaea viscosa). 6.1.3 Deliverable(s) Map the impact footprint of BHP Billiton Olympic Dam activities for the Environmental Management and Monitoring Report. 6.1.4 Method Monitoring of symptoms occurs within, and surrounding, the Special Mining Lease surrounding the Olympic Dam operation. Monitoring is centred on the main sources of emissions: the main smelter stack (as the source of copper (Cu) and SO2), the raise bores (as the source of saline aerosols) and the Backfill Quarry (as the source of dust). Sampling is undertaken in two stages:  sample sites are located on a radial grid pattern with the distance between sample points increasing exponentially out from the centre of the grid (the centre being near the Main Smelter Stack) to a maximum distance of 25 km to locate the approximate extent (front) of each of the emissions impacts.  sampling on a dense though irregular pattern in and around the ‘fronts’ (detected during the radial sampling) for each of the symptoms to be modelled. At each location on the radial grid and the ‘front’ sampling, five individuals of each of the two indicator species, A. ligulata and D. viscosa, are selected to identify the presence or absence of each of the following 13 symptoms listed below:  necrotic spots, leaf tip necrosis, apical chlorosis, marginal chlorosis, dorsiventral colour contrasts, deformations, stagging, dead twigs retaining leaves, excessive leaf abscission, leaf dulling, major new growth, salt crystals and death. A symptom is recorded as present if evident to any extent and the symptom count is derived from the percentage of foliage affected. The five individuals are those nearest the sampling point and within a radius of 50 m of the point. If one or both species are not present within 50 m of the point, no sample is recorded for the absent species. 6.1.5 Results/Discussion In FY11, 24 new sites were added to the sampling grid. Sites sampled in FY11 are shown in Figure 6-1. During the FY11 monitoring period, sites EV916 and EV928 were inaccessible due to operational activities. The modelled footprint of detectable emission levels in plants for FY11 covered 2,500ha. This included a high impact area centred on the Olympic Dam operation (Figure 6-2). Ignoring two outliers, individual sites with a ‘detectable’ impact were recorded up to 4.5km from the Main Smelter Stack, and sites with a ‘high’ impact up to 2km from the Main Smelter Stack. Whilst most sites with symptoms were centred on, and relatively close to, the main Olympic Dam operation, there were records of dead A. ligulata or D. viscosa at one site each, 25-26km east or south-east of the operation. As no symptoms were observed on the sites intervening between these sites and the Olympic Dam operation, these symptoms at the two outliers were interpreted to be the result of other factors, not the operation (Griffin and Dunlop, 2010a)

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Figure 6-1: Location of radial sample sites and front sites monitored in FY11 The total area modelled as having a ‘detectable’ and ‘high’ impact has remained reasonably constant since this form of monitoring was introduced, varying between 2,300ha (FY08) and 2,650ha (FY07) (Table 6-1; Figure 6-2). The FY11 figure, 2,500ha, lies in the middle of this range. This is 100ha larger than that identified in FY10. Where areas were affected, there were likely to be slightly fewer plant symptoms than in FY10: the area covered by a ‘high’ impact had decreased whereas that associated with a ‘detectable’ impact had increased. In FY10 it was suggested that the decreased area in FY10 compared with FY09 may have partly reflected the higher rainfall in the 12 months preceding the FY10 sampling, compared with rainfall preceding the FY09 sampling (Griffin and Dunlop, 2009). In contrast, rainfall prior to the FY11 sampling was even higher than in FY10, yet the detectable impact had increased slightly rather than decreased. It may be that without the relatively high rainfall, there would have been a larger increase in detectable impact. FY11 rainfall data can be found in Appendix 2 (Figure 14-1) of this report. FY10 rainfall data can be viewed in the FY10 EMMR (BHP Billiton 2010e). Table 6-1: Areas of modelled impact for symptoms since FY07 and change between FY10 and FY11 (areas modelled to the nearest 50ha)

Impact category Change FY07 FY08 FY09 FY10 FY11 FY10-FY11 Total footprint 2,650 2,300 2,600 2,400 2,500 100 Detectable 2,350 1,600 1,650 1,800 2,000 200 High 350 700 950 550 500 -50 Extreme 0 0 0 0 0 0

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Figure 6-2: Modelled distribution of symptoms in FY11 in and about the operation

6.2 Long Term Changes to Perennial Vegetation 6.2.1 Background Changes in the composition and structure of vegetation surrounding the Olympic Dam operation have occurred as a result of emission impacts (Fatchen Environmental, 2005). Fatchen reported that in areas that continue to be affected by emissions, recovery, either from regrowth of damaged individuals, or recruitment of new plants, may be depressed or even inhibited. Whilst the impact to individual plants is currently monitored (Section 6.1), no data is collected on the long term effect of these emissions, if any, on plant communities,

FLORA MONITORING PROGRAM Page 71 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT specifically perennial plant communities. Perennial species are persistent and are an ideal indicator group as they are not likely to change in abundance in response to season or to most short mesic or xeric periods. Recruitment is likely to be aperiodic and in response to unusually high rainfall periods (Griffin and Dunlop, 2006). By collecting annual data at different proximities from the emission sources and using simple assessment methods, changes in perennial plant communities as a result of emissions can be monitored. 6.2.2 Purpose To determine what impact, if any, Olympic Dam Operations has on perennial plant communities surrounding the operation. 6.2.3 Deliverables  Report on the annual changes in perennial communities surrounding the Special Mining Lease and surrounds in the Environmental Management and Monitoring Report.  Provide a comparative assessment on perennial species existing at different proximities from the main stack. 6.2.4 Method A total of 46 long term vegetation monitoring sample sites are located in a radial grid (centred on the Main Smelter Stack) surrounding the Olympic Dam operations. Sites are located up to 25 km from the centre (Griffin and Dunlop, 2006).The exact locations of these sites can be seen in Figure 6-1 of this report. Note: EV939, EV929, EV925, EV911, EV910 and EV940 are not sampled as they do not fit the criteria required for this sampling. At each of the sites on the radial grid, a sample quadrat 100m  25m is assessed for perennial vegetation species. Within the quadrat the frequency of occurrence is recorded for all perennials. Annual monitoring of these sites and vegetation composition is undertaken to detect if emission impacts continue and, if so, their effects on plant communities. 6.2.5 Results/Discussion During FY11, 24 new sites were added to the sampling grid. Comparisons with previous years at these sites was therefore not possible, however the data will be utilised in future reporting. During FY11 monitoring sites EV916 and EV928 were inaccessible due to operational activities. Changes in monitored vegetation Conditions in FY11 were relatively wet in comparison to previous years, which is the likely cause for the recruitment of many small A. ligulata growing at most sites (even ones with no other A. ligulata). Heavy herbage cover prevented an accurate count of these seedlings. In addition, it was expected that most of these plants would not survive to FY12. For this reason, it was decided to exclude small A. ligulata from the count if they were still showing juvenile pinnate foliage. In FY12, a review of which of these small plants did survive will be undertaken, and the FY11 data adjusted accordingly, so that only cases of genuine recruitment are included. Between FY10 and FY11, species composition changed at 42 of the 44 sites where comparison was possible. Summed over each species and site, the counts of plant numbers per site changed by 227 plants in FY11 compared to FY10 (in some cases representing recruitment and in others plant deaths) (Figure 6-2). This was slightly lower than the change between FY09 and FY10 for the same 44 sites (244 plants). However, over FY09-10, net plant deaths far outweighed net recruitment, with a net loss of 114 plants (65 new plants less 179 plant deaths). In contrast, net deaths and

Page 72 FLORA MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT recruitments were relatively equal over FY10-11, with a net loss of only nine plants (Table 6-3). Table 6-2: Changes in quadrat species counts FY10-11, for sites sampled in both years (n=44 sites)

No. plants in Total Net Species Net died FY11 changes recruited Acacia aneura 17 2 2 0 Acacia ligulata 730 104 21* 83 Acacia ramulosa 72 2 1 1 Alectryon oleifolius 81 3 1 2 Dodonaea viscosa 771 50 28 22 Eremophila longifolia 42 8 8 0 Gunniopsis quadrifida 70 39 39 0 Pimelea microcephala 1 1 1 0 Santalum lanceolatum 3 1 0 1 Senna artemisioides 187 17 8 9 Total (for these species) 1,974 227 109 118 Note:  Only includes those species whose count per quadrat differed for at least one quadrat between FY10 and FY11. The ‘total changes’ are the sums of net gains (in some quadrats) and net losses (in other quadrats). Gains and losses within an individual quadrat are not shown; instead the net effect, the total number of plants, was recorded.  *Note that this figure may be revised upwards, once genuine recruitment can be assessed.

Table 6-3: Changes in the total number of plants FY07-11, for sites sampled in over those years

Total no. plants Net change from Total no. plants Net change from Year (28 sites) previous year (44 sites) previous year

FY07 1,542 N/A N/A N/A FY08 1,509 -33 N/A N/A FY09 1,398 -111 2,150 N/A FY10 1,327 -71 2,036 -114 FY11 1,348 21 2,027 -9  Note. The numbers of plants reported in Table 6-3 are calculated for sites which were sampled in FY07-11 (first set of plant numbers), and for the larger set of sites which were sampled in FY10-11 (second set of plant numbers). ‘Net change’ equals net gains minus net losses. Plant diversity Simpson’s index is a measure of the extent to which sites were dominated by one or a few species. Modelled dominance was generally highest near the operation and lowest distant from the operation (Figure 6-3). Indeed, areas close to the centre of the operation were modelled with the maximum dominance (1.0, i.e. only one species present, in this case, A. ligulata). Areas at the perimeter were modelled with greatest plant diversity at the scale of the model (<0.1). There was, however, a high degree of variation amongst the more distant sites. The plot of Simpson’s index was very similar to that in FY10 (cf. Griffin and Dunlop, 2010b).

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Figure 6-3: Modelled surface of Simpson’s index. The contours represent the modelled level of dominance based on the values from the sample sites (red dots)

6.3 Land Disturbance 6.3.1 Background Various resource drilling, mine, process and development related activities involve the clearance of vegetation and ground surface for access tracks, drill pads, drilling sumps, lay down areas, quarries, surface soil stockpiles, general excavation and waste management areas. The results of all development activities include:  clearance of topsoil and vegetation (for the construction of drill pads and access tracks, extraction of sand from dunes and rock quarrying, etc.); and,  the alteration of surface soils and surface water flows. All activities that result in land clearance are subject to the Environmental/Indigenous Heritage Clearance Permit (EIHCP) procedure.

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The extent of land disturbance and the impact of drilling activity are controlled through site procedures developed with earthworks contractors and drilling crews. Waste management and infrastructure expansion is subject to the approval of the appropriate authorities and is regulated through discussions with planning personnel and site procedures developed with earthworks contractors. 6.3.2 Purpose  Define the disturbance impact footprint of infrastructure, development, resource drilling and associated waste management activities.  Ensure all disturbance activities have been undertaken in compliance with the EIHCP system. 6.3.3 Deliverable(s) Define and map the disturbance impact footprint of Olympic Dam’s activities for the Environmental Management and Monitoring Report 6.3.4 Method The extent of physical land disturbance is measured using GIS technology. Geo- referenced aerial photographs of the Special Mining Lease and Municipal Lease are analysed for physical disturbance during the period prior to the photographs being taken. Evidence of disturbance will be cross-referenced against the EIHCP system records for the same period. For land disturbance occurring following the capture of aerial photography through until the end of the reporting period, the area will be calculated from the EIHCP database. 6.3.5 Results/Discussion Spatial analysis techniques were utilised on geo-referenced orthoimagery for the period June 2010 to July 2011. During this reporting period, satellite imagery of the vast majority of the SML was captured on a quarterly basis, offering a more accurate account of the timing of land disturbance. Satellite imagery (captured in July 2010, October 2010, December 2010 and June 2011) was used in conjunction with aerial photography of the whole SML (captured in June 2010 and June 2011) to identify new areas of land disturbance. Disturbances identified as occurring between these dates were digitised and are represented in Figure 6-4. The total area of disturbance that occurred between June 2010 and July 2011 is 423.8ha (Table 6-4). The majority of disturbance in FY11 is attributed to the construction of TSF5 (399.2ha). Other disturbance areas include the construction of the Tailings Disposal Unit pipe trace and the expansion of the quarry. All activities that resulted in land clearance during the reporting period were undertaken in accordance with the EIHCP process. Table 6-4: Areas of disturbance on the SML from June 2010 to July 2011

Facility Area (hectares) Mine Facilities 16.9 Miscellaneous Facilities 1.8 Tailings Facilities 399.2 Exploration 5.9 Total 423.8  Note: Disturbance on the SML has been allocated to certain facilities such as mine or tailings etc. depending upon where they are situated or their purpose. For example, drill pads in the Olympic Dam Expansion exploration area have been allocated to mine facilities.

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Figure 6-4: Disturbance on the SML between June 2010 and July 2011

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6.4 Pest Plants 6.4.1 Background Weeds within the Olympic Dam region are managed through the Weed Management Strategy (BHP Billiton Olympic Dam, 2010a), a collaborative effort driven by BHP Billiton Olympic Dam, in conjunction with Arid Recovery, the Roxby Downs Municipal Council and the Andamooka Progress and Opal Miners Association. The Weed Management Strategy (2010a) takes significant direction from other over-arching National and Regional Pest Strategies, especially the South Australian Arid Lands (SAAL) Natural Resource Management (NRM) Pest Management Strategy. The Weed Management Strategy (BHP Billiton Olympic Dam, 2010a) includes a risk assessment of weed species that are currently found within the Olympic Dam region or which may become a problem in future. In the Weed Management Strategy (BHP Billiton Olympic Dam, 2010a), weeds risk is assessed according to two different habitat types: Developed and Rangeland. A detailed description of the two habitat types can be found in the Weed Management Strategy (BHP Billiton Olympic Dam, 2010a), Section 3.1. Weeds have been ranked, taking into consideration their invasiveness potential and feasibility to control. Weeds that have an extreme risk or high risk status are species which Olympic Dam will monitor and control. 6.4.2 Purpose Determine the extent of weed infestations of extreme risk and high risk weed species within the Olympic Dam region and Special Mining Lease. 6.4.3 Action Triggers All infestations of species declared under the Natural Resources Management Act 2004 must be controlled in accordance with the act. Species declared under the Act (as of Jan 2010) that are knowingly present within the Olympic Dam region are; Prickly Pear, Innocent Weed, Bathurst Burr, Caltrop, Salvation Jane, Onion Weed and Athel Pine. African Boxthorn and Horehound are also found within BHP Billiton’s HV Powerline corridor from Pt Augusta and Olympic Dam. If any declared species are found on BHP Billiton leased land, control and any government notification requirements are to be initiated in accordance with the relevant provisions under the Act. 6.4.4 Deliverable(s) Define and map the current distribution of extreme risk and high risk weed species within the Olympic Dam region and Special Mining Lease. 6.4.5 Method The current distribution of extreme risk and high risk weed species is determined during scheduled weed monitoring. Comprehensive biennial monitoring is conducted every 18 months, thereby alternating between a summer survey period and a winter survey period. Routine and opportunistic monitoring is still conducted in high risk habitats and previous control locations. Areas surveyed include the Special Mining Lease, the Municipal Lease, pastoral leases and the Arid Recovery reserve. The next scheduled biennial monitoring will be undertaken in August 2011. 6.4.6 Results/Discussion Routine and opportunistic observations were undertaken throughout the reporting period as per the Weed Management Strategy. Significantly higher rainfall throughout the reporting period led to an abundance of various pest plant species growing in previously unknown areas. A total of 85 plant species have been recorded and identified as weeds, of which three species have been identified as Extreme risk and 16 identified as High risk ( In many cases a single GPS location may reference a large

FLORA MONITORING PROGRAM Page 77 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT infestation area, distribution of weeds such as Ruby Dock, Salvation Jane, Caltrop and Blackberry nightshade may be more extensive than appears on the map below. In the developed habitat, three species of Extreme risk and 11 species of High risk were identified; and in rangeland habitat, one species of Extreme risk and seven species of High risk were identified. Control efforts for these species were undertaken throughout FY11. Existing infestations of all known Extreme risk species in a developed habitat were subject to significant control efforts. Removal of Athel Pine trees continued during FY11 (Figure 6-5) as per EMP targets and action plans. Innocent Weed was continually monitored and controlled over the summer months (Figure 6-6). It is worth noting that despite flooding of the infestation areas over FY10-11, the infestation density appears to be declining at some locations. Noxious Weed information signage was erected at four earth drains within Roxby Downs to reduce the potential of soil movement where Innocent Weed (Cenchrus incertus) is present. New infestations of Buffel Grass were identified and physical and chemical control techniques were implemented. There appeared to be an increase in the occurrence of infestations along roadsides (main roads) and this will be closely monitored in the future. Significant rainfall throughout FY10 and FY11 provided ideal conditions for many weed species. Extensive infestations of (in particular) Ruby Dock, Salvation Jane and Buffel Grass emerged. Control of these species was undertaken at several locations on the SML and ML. It is anticipated that the high rainfall will have had an impact on the spread of declared plants over future monitoring seasons. The FY11 distribution of Extreme and High risk species is shown in Figure 6-7 to Figure 6-13. In many cases a single GPS location may reference a large infestation area, distribution of weeds such as Ruby Dock, Salvation Jane, Caltrop and Blackberry nightshade may be more extensive than appears on the map below. Table 6-5: Pest plant species that pose an extreme or high risk

Risk Extreme High Athel Pine Blackberry Nightshade Caltrop Fountain Grass Buffel Grass Onion Weed Paddy Melon Developed habitat Innocent Weed Potato Weed Ruby Dock Prickly Pear Salvation Jane Three-Corner Jack White Cedar Bathurst Burr Buffel Grass Caltrop Horehound Rangeland habitat Prickly Pear Saffron Thistle Salvation Jane Wards Weed

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Figure 6-5: Athel Pine control efforts continued on the SML during FY11. Seven regenerating Athel Pine plants were controlled along Eagle Way. Photo taken 5 weeks after control efforts undertaken

Figure 6-6: Control efforts of Innocent Weed within the Myall Grove reserve during summer FY11. Example of ‘Noxious Weed’ signage installed at earth drains in Roxby Downs, where Innocent Weed infestations are known to occur

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Figure 6-7: Distribution of Extreme and High risk weed species on the SML in FY11

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Figure 6-8: Distribution of weed species at Olympic Dam Village (within the Municipal Lease) in FY11

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Figure 6-9: Distribution of weed species in the Roxby Downs urban area (in the Municipal Lease) in FY11

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Figure 6-10: Distribution of weed species in the Arid Recovery reserve in FY11

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Figure 6-11: Distribution of weed species on Andamooka Station (including Andamooka township) in FY11

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Figure 6-12: Distribution of weed species on Roxby Downs Station and Purple Downs Station in FY11

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Figure 6-13: Distribution of weed species on Stuarts Creek Station in FY11

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6.5 GAB Spring Vegetated Wetland Area 6.5.1 Background The rate of artesian flow from a GAB spring is directly correlated with the area of vegetated wetland and are also a valuable proxy for the assessment of GAB spring flow (Williams and Holmes 1978). Changes in the area of vegetated wetland may influence populations of threatened flora and endemic invertebrates. Changes in wetland area may be used to assess the extent of aquifer drawdown resulting from water extraction. Research has proven that GIS techniques can be used to determine the size of vegetated wetland (Niejalke and Lamb 2002). This method involves less field time and is deemed more accurate than field assessments. 6.5.2 Purpose Quantify the change in GAB spring vegetated wetland area that may be attributed to water extraction from the wellfields. 6.5.3 Action trigger(s) Evidence that flow reductions (measured as a reduction in wetland area data) at GAB springs may exceed the predictions made in the Environmental Impact Statement (Kinhill Engineers 1997) and Kinhill Stearns 1984 (refer to Appendix 5 in the Monitoring Program - Great Artesian Basin - OLYMPIC DAM Document No: 2789). 6.5.4 Method The area of GAB spring wetland is calculated triennially using geo-referenced aerial photography (Niejalke and Lamb 2002). Imagery is captured in the first year of the Environmental Management Manual (EMM) triennium, with area reported in the second year of the EMM triennium. Additional monitoring currently undertaken on the springs, spring flow rate (biannually) and aquifer pressure (monthly/quarterly), will be used to identify any gross change and may trigger a field assessment between photography capture. The aerial photography of the vegetated wetlands of GAB springs is classified using ER Mapper software and the classified area is calculated using ArcGIS software. This technique is not appropriate for some springs due to their small size, or for the small number of wetlands that do not support wetland vegetation. Therefore, these springs are assessed using field techniques. To simplify analysis, spring groups are allocated to predicted impact zones that reflect the anticipated level of hydrological influence caused by water extraction from the wellfields (see Figure 8.3, Monitoring Program - Great Artesian Basin - OLYMPIC DAM Document No: 2789). These impact zones are used in analysis to determine the impact of water extraction from the wellfields. Wetlands may also be grouped into categories depending on their biological complexity and the elevation of the spring vent. GAB spring groups to be analysed using the GIS technique should include those listed in Appendix 5 of the Monitoring Program - Great Artesian Basin - OLYMPIC DAM Document No: 2789. Wetland size is compared with the previous reported measurement to determine the impact, if any, of drawdown. Springs that show a significant difference in measurement are visited to determine possible causes. 6.5.5 Results/Discussion Mound spring imagery was acquired on 20 May 2011, and analysis of this data is currently being undertaken. Wetland vegetated areas will be reported in FY12 in line with the triennial reporting process.

FLORA MONITORING PROGRAM Page 87 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT 6.6 At-risk Species – Category 1 A number of at-risk flora species have been recorded within the project area. At-risk species are those where isolated populations or the species population as a whole have the potential to be adversely impacted by the operations. Species include formally listed species under state or national conservation listings and other significant species defined by BHP Billiton Olympic Dam. At-risk species have been classified by BHP Billiton into three main categories, Category 1a, Category 1b and Category 2. Category 1a includes those at-risk species whose population distribution as a whole is largely restricted to the impact area and therefore the species has a higher risk of being impacted by the operations. This includes flora species restricted to the GAB springs of the Lake Eyre South region in the vicinity of the wellfields. The degree of at-risk species monitoring depends largely on the category under which they fall. Monitoring of Category 1a species is intensive in comparison to Category 1b and Category 2 species (Section 2.7), which reflects the species’ reliance on the potential impact area. A list of all at-risk flora occurring in the impact zone is included in Section 9. Section 10 contains a flow chart detailing how at-risk species are identified. 6.6.1 Background A diverse and rare group of flora is found within mound springs of the Great Artesian Basin in South Australia and Queensland. These landforms occupy an extremely small percentage of semi-arid Australia, and are probably the rarest landform on the continent (DEH 2006). Eriocaulon carsonii is a distinctive plant restricted to the active mound springs of the GAB, where it is reliant on a constant supply of flowing water. The largest single population exists at the Hermit Hill spring complex near Wellfield A. Eriocaulon carsonii is listed as endangered by state and national legislation. BHP Billiton Olympic Dam has the potential to alter the flow of mound spring water within the GAB, which may have an adverse effect on E. carsonii populations. 6.6.2 Purpose Determine if the distribution and abundance of E. carsonii is affected by water extraction from the wellfields. 6.6.3 Action Trigger(s) Evidence that indicates unacceptable harm or detriment to rare or threatened species or ecological communities that can be attributed to drawdown caused by extraction from Wellfields A or B. 6.6.4 Methods The relative abundance of E .carsonii is estimated using the Domin cover-abundance scale (Kershaw and Looney 1985). Changes in the cover abundance and the proportion of GAB springs supporting E. carsonii are used to assess the dynamics of the population. To simplify analysis, spring groups are allocated to predicted impact zones that reflect the anticipated level of hydrological influence caused by water extraction from the wellfields (see Figure 8.3, Monitoring Program - Great Artesian Basin - OLYMPIC DAM Document No: 2789). 6.6.5 Results/Discussion Within the region studied, populations of E. carsonii were restricted to 19 spring units in the Hermit Hill and Lake Eyre springs complexes in FY11. It occurred on the Hermit (12 units), North West (1), Gosse (3), Sulphuric (1), Old Finniss (1) and West Finniss (1) spring groups. Eriocaulon carsonii was uncommon and limited in abundance where it did occur. It ranged in cover class on any one spring unit from 1 (< 0.1% cover) to 6 (26-33%

Page 88 FLORA MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT cover), with a median cover of 0.1-< 1%. Eriocaulon carsonii occurred on spring mounds/springs and spring tails. Eriocaulon carsonii appeared on ten new spring units between the baseline years and FY11 (in addition to being transplanted to the spring HSS012). It disappeared from 15 spring units between the baseline years and FY11. Some problems with the historical data are discussed below, meaning some records of apparent local extinction or re-colonisation of E. carsonii should be interpreted with caution. Table 6-6 and Table 6-7 include only those spring groups where E. carsonii has been recorded at some time during or between 1983/4 and FY11. Between the baseline year and FY11, the distribution of cover classes has shifted. The higher cover classes of 1983/4 had declined by FY10 and FY11. There have been significant declines in the Hermit spring group (Table 6-7). Whilst there were some changes in E. carsonii cover for individual spring units between FY10 and FY11, the changes were not significant at the spring group or impact zone level (Table 6-6). Table 6-6: Changes in Eriocaulon carsonii abundance, FY10 – FY11 (n=131)

Sampling units where Eriocaulon carsonii:

Spring group Disappeared Decreased Showed no change - present Showed no change - absent Increased Appeared Chi-square t-test n Hermit Hill impact zone Hermit 0 1 10 27 1 0 NA NS 39 Old Finniss 0 0 1 18 0 0 NA NA 19 North West 0 0 1 33 0 0 NA NA 34 Gosse 0 0 3 3 0 0 NA NA 6 Zone total 0 1 15 81 1 0 NA NS 98

Northern Sub-basin (Lower) impact zone West Finniss 0 0 1 23 0 0 NA NA 24 Sulphuric (transplants) 0 0 1 8 0 0 NA NA 9 Zone total 0 0 2 31 0 0 NA NA 33  Significance: NS = not significant; NA = not applicable (insufficient data to test)  Note: The chi-square is testing changes in the presence or absence of E. carsonii between the comparison years (in this case, FY10 and FY11). The t-test tests the change in abundance of E. carsonii within a spring group.

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Table 6-7: Changes in Eriocaulon carsonii abundance, baseline – FY11 (n=103)

Sampling units where Eriocaulon carsonii:

Spring group Disappeared Decreased Showed no change - present Showed no change - absent Increased Appeared Chi-square t-test n Hermit Hill impact zone Hermit 12 6 0 15 0 5 NS *** 38 Old Finniss 0 0 0 18 0 1 NS NA 19 North West 0 0 0 6 0 1 NS NA 7 Gosse 0 0 0 3 0 3 NS NA 6 Zone total 12 6 0 42 0 10 70 Sub-total for Hermit and Old Finniss spring groups 12 6 0 33 0 6 NS *** 57

Northern Sub-basin (Lower) impact zone West Finniss 3 1 0 20 0 0 NS NS 24 Sulphuric (transplants) 0 0 0 8 0 1 NS NA 9 Zone total 3 1 0 28 0 1 NS NS 33  Significance: NS = not significant (p≥0.05); NA = not applicable (insufficient data to test), *** p<0.001.  Note. For all spring groups reported in the above table except North West, the baseline year was 1983/4. The baseline year for the North West spring groups reported here was 1988 (Of the 34 monitored springs in the North West spring group, the baseline year was variously 1988 (28 spring units), FY06 (4) and FY07 (2). 1988 E. carsonii data are missing for 21 of the sites with this year as baseline year). As there is some doubt about the 1983/4 Gosse results, the statistical tests for the Hermit Hill impact zone combined data have been applied only to the two spring groups with reliable 1983/4 baseline year data. Hermit Hill impact zone Between FY10 and FY11, E. carsonii did not change in cover on 15 spring units, increased in cover on one spring unit, and decreased in cover on one. Between 1983/4 and FY11, E. carsonii increased in cover (was recorded for the first time) on nine spring units and decreased in cover on six spring units. However, there is some doubt as to the accuracy of the 1983/4 records for three of these spring units (reporting the appearance of E. carsonii at the Gosse spring group). It disappeared from 12 spring units over this period. The change in cover for the impact zone for this time period was significant. For those spring units with a 1988 baseline year (from the North West spring group), E. carsonii was recorded for the first time on one spring unit between 1988 and FY11. Northern Sub-basin (Lower) impact zone Between FY10 and FY11, E. carsonii cover was constant on two spring units. E. carsonii declined in cover on one spring unit and disappeared from three spring units between 1983/4 and FY11. The only other change represents plants transplanted in the intervening years. The changes in occurrence were not significant at the impact zone level.

Page 90 FLORA MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT 6.7 At-risk Species – Categories 1b and 2 Category 1b includes at-risk species that have an important population (where there are few other populations within the region or interstate) that may be critically reliant on the area of impact and the population has the potential to be impacted. Currently there are no at-risk flora species that fall into category. Category 2 includes at-risk species whose population as a whole is not critically reliant on the potential area of impact i.e. only individual species are likely to be impacted. This includes species which have a wider distribution within the state, interstate or overseas and are not considered to be dependant upon existing populations within the impact area. The degree of at-risk monitoring depends largely on the category under which they fall. Monitoring of Category 1 species (Section 0) is intensive in comparison to Category 2. 6.7.1 Background There have been 26 at-risk species recorded within the Olympic Dam Special Mining Lease, Municipal Lease, Pastoral Leases, Transmission Line and the Wellfields area. All species, with the exception of Eriocaulon carsonni (Section 6.6.1), were found to be non- dependent on the populations which exist within the impact area and have been classified as Category 2. This includes species that are not listed as threatened, but are considered to be regionally/locally significant. No specific monitoring programs apply to individual Category 2 species however all at-risk species are protected where possible under the Environmental Indigenous Heritage Clearance Permit procedure implemented for all disturbance works related to BHP Billiton activities. This includes species that are not legally required to be protected but have the potential to be adversely impacted by operations. If a Category 1b or 2 species is elevated to Category 1a, then a more intensive monitoring/protection program will be implemented. 6.7.2 Purpose Determine if there is a requirement to implement any management activity for the protection of Category 1b and 2 species in the vicinity of the operations. 6.7.3 Deliverable(s) Identify if additional management activity is required for Category1b and 2 at-risk species through risk-based assessments. 6.7.4 Method Locations will be collected opportunistically for annual and or ephemeral at-risk species after periods of substantial rain and added to the Environmental and Indigenous Heritage Clearance Permit spatial database for future reference. Locations of these species and perennial Category 1b and 2 species will be considered when Environmental and Indigenous Heritage Clearances are undertaken 6.7.5 Results/Discussion Category 2 at-risk species are identified during EIHCP assessments and other environmental surveys. Wherever possible these species are avoided or protected to limit the impact from operations and associated disturbances. No Category 2 species listed under state or national legislation have been knowingly disturbed in FY11. Category 2 flora species impacted by disturbance activities during FY11 are listed in Table 6-8. Acacia aneura and Alectyron oleifolius are common trees species prevalent on the SML, Municipal Lease and pastoral leases. These species are included in the Category 2 species list as they are long-lived and slow growing species with limited recruitment opportunities. Efforts are made to avoid these species where possible. During FY11 a significant area was cleared of vegetation for the construction of Tailings Storage Facility (TSF) 5, these species were impacted by this disturbance.

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One new population of Orobanche cernua var australiana, a Category 2 species listed as rare under the National Parks and Wildlife (SA) Act 1972, was identified within the Wellfield area during the reporting period. Table 6-8: Category 2 species identified in areas subject to land disturbance

Species Impacted by land New location identified disturbance in FY11 FY11 (s = seedling) (a = adult) Acacia aneura  - Alectyron oleifolius  - Orobanche cernua var australiana 

6.8 Conclusion  The total area of detectable impact for FY11 was 2,500ha. This is 100ha larger than that identified in FY10. Where areas were affected, there were likely to be slightly fewer plant symptoms than in FY10: The area covered by a ‘high’ impact had decreased whereas that associated with a ‘detectable’ impact had increased.  Twenty four new sites were added to the radial sampling grid in FY11. These sites enabled baseline data to be collected at more sites at a distance from the existing operations which should benefit data analysis for the Long Term Vegetation Monitoring Program when comparisons can be made next year.  The estimated total area of disturbance that occurred between June 2010 and July 2011 was 423.8ha.  Above average rainfall in the year preceding and during FY11 resulted in a high number of pest plant infestations within the control area. Known infestation areas were monitored and controlled with a focus on Extreme risk species.  Whilst there were some changes in Eriocaulon carsonii cover for individual spring units between FY10 and FY11, the changes were not significant at the spring group or impact zone level.  Two common, locally significant Category 2 species were impacted upon during FY10. This was the result from continued vegetation clearance associated with the construction of TSF5 where it was not possible to avoid individual species.

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7 AIRBORNE EMISSIONS MONITORING PROGRAM

7.1 Smelter 2 Emissions 7.1.1 Background Smelter 2 is one of the major sources of airborne emissions at Olympic Dam and comprises a Flash Furnace, Electric Slag Reduction Furnace, two Anode Furnaces and an Acid Plant. Off-gas from the Flash Furnace is directed to the Electrostatic Precipitator, which removes particulate matter for recycling to the furnace before being directed to the Acid Plant. Here the sulphur dioxide (SO2) is converted and absorbed to produce sulphuric acid for use in the metallurgical plant. Unconverted SO2 is directed to the Acid Plant Tails Gas Stack and discharged to atmosphere. Electric Furnace off-gas is directed to a quench tower and venturi scrubber gas cleaning system before release to the atmosphere via the Main Smelter Stack. Anode Furnace off-gas is treated in gas cleaning systems similar to that of the Electric Furnace with the exception of sulphur dioxide rich oxidation gases that are directed to the Acid Plant for conversion to sulphuric acid. All furnaces have gas cleaning system bypass stacks in addition to the Main Smelter Stack and the Acid Plant Tails Gas Stack, for use in abnormal or emergency situations. In addition, the Acid Plant also has a bypass stack for use in abnormal or emergency situations in the Acid Plant or during planned maintenance activities. 7.1.2 Purpose To monitor air emissions from Smelter 2. 7.1.3 Deliverable(s)

 Calibration of and record retention for SO2 analysers on the Main Smelter Stack and Acid Plant Tail Gas Stack.  Compliance with the emission limits, monitoring and reporting requirements of EPA Licence 1301, EPA Exemption 3014 and the Environment Protection (Air Quality) Policy 1994.

 SO2 recovery of greater than 99%. 7.1.4 Method The impact of specific emissions on air quality is assessed through monitoring operational compliance against the requirements and emission limits specified in EPA Licence 1301, EPA Exemption 3014 and the Environment Protection (Air Quality) Policy 1994. Olympic Dam maintains systems to report bypass and exceedance emission events in accordance with statutory and other obligations. If either of the Anode Furnaces, Electric Furnace, Flash Furnace or the Acid Plant Bypass stacks have been operated for a period of greater than 10 minutes duration, a report is automatically generated by the process control system. Similarly, at the completion of every 12-hour shift (at 0600 and 1800) a report is automatically generated by the process control system detailing the 30-minute average SO2 concentrations for the Main Smelter Stack and the Acid Plant Tails Gas Stack for the duration of the shift. If at any time, SO2 emissions from the Main Smelter Stack or Acid Plant Tails Gas Stack exceed 2400mg/Nm3 (except during conditions specified in the EPA Exemption 3014), Olympic Dam is required to notify EPA Regulation and Compliance within one working day of the event.

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All emission events likely to result in an exceedance of the National Environment Protection (Ambient Air Quality) Measure (NEPM) limits for ground level concentrations of SO2 are modelled using the CALPUFF Emission Dispersion Model (see Section 2.4). In the event of an exceedance of the NEPM limits, Olympic Dam is required to notify EPA Regulation and Compliance within one working day of the event. All information on bypass and exceedance emission events is compiled monthly to form the Notification of Emission Events report. This report is submitted to EPA Regulation and Compliance within ten working days from the completion of the month. All other relevant information is available to EPA Regulation and Compliance on request. Isokinetic stack sampling is performed in accordance with condition (305-137) of EPA Licence 1301. Sampling of Smelter stack emissions and intermediate process gases are undertaken as necessary to ensure gas cleaning systems are operating optimally and in compliance with prescribed limits based on process control data obtained from the process control system. This sampling typically includes analysis for SO2, sulphur trioxide (SO3), particulates, heavy metals and other chemical compounds. Results from this sampling are used to update the emission profiles used in the generation of emission dispersion maps and to validate the continuous emission monitoring (CEM) results. 7.1.5 Results/Discussion

The SO2 analyser in the Main Smelter Stack which was installed in FY10 had no major outages during the reporting period. From January to May however readings from the analyser started to drift. This was caused by an issue with build-up on the internal lens, combined with contamination of the nitrogen span calibration gas due to the incorrect gas being supplied. This was rectified by a manufacturer service technician in May. For the remainder of the period it was maintained in accordance with site procedures and manufacturers recommendations. A new SO2 analyser was installed in the Acid Plant Tail Gas Stack in July 2010. For the remainder of the reporting period it was maintained in accordance with site procedures and manufacturer’s recommendations. Isokinetic sampling of the Main Smelter Stack and Acid Plant Tail Gas Stack was undertaken in June 2011. The results indicate continued compliance with the requirements of EPA Licence 1301 and the Environment Protection (Air Quality) Policy 1994 (Table 7-1). The results have decreased when compared to FY10, however they remain consistent with measurements from previous monitoring periods. Table 7-1: Smelter 2 Stack Sampling Results June 2011

Sampling Point Total acid gas Sulphur trioxide Particulate emissions* and acid mist emissions (mg/Nm3) emissions* (mg/Nm3) (mg/Nm3) Regulatory Limit 3000 100 100

Main Smelter Stack 78 3 16 Acid Plant Tail Gas 766 3 0.8 Stack  * Expressed as sulphur trioxide equivalent

The average SO2 recovery percentage for the reporting period was 97.88%. This recovery result has decreased from the previous reporting period (99.28%). Notifiable emission events have increased from 176 events in FY10 to 194 events during FY11, representing a 10% increase. Considering the Smelter and Acid Plant were both shutdown for approximately four months in FY10, this reporting period does not represent a full production year. When comparing FY11 notifiable emission events with FY09 the number of events has decreased by 25%.

Page 94 AIRBORNE EMISSIONS MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT 7.2 Calciner Emissions 7.2.1 Background The precipitation area of the Hydromet includes two calciners (Calciners A and B), each with its own off-gas cleaning system and gas discharge stack. Ammonium Diuranate (ADU) enters the calciners after the completion of the solvent extraction and precipitation stages of the uranium recovery process. The ADU is calcined to uranium oxide concentrate (UOC), which is subsequently packed and prepared for shipping. The off-gas from the individual calciners passes through venturi scrubbers, droplet separators and mist eliminators to remove particulates prior to release to atmosphere. 7.2.2 Purpose To monitor emissions of particulates from the calciners. 7.2.3 Deliverable(s) Compliance with emission limits specified in Environment Protection (Air Quality) Policy 1994. 7.2.4 Method The impact of specific emissions on air quality is assessed through monitoring the compliance of processes against emission limits specified in the Environment Protection (Air Quality) Policy 1994. Particulate emissions from Calciners A and B are measured on a quarterly basis by isokinetic sampling, where possible, depending upon process reliability and plant availability. Any measurement above 250mg/Nm3 is investigated and reported to EPA Regulation and Compliance within one working day. The isokinetic stack-sampling filters used to capture particulates are also analysed for Uranium-238 (238U) activity. Results from this, together with data obtained from the process control system, are used to estimate total uranium discharged from the stacks, which is subsequently reported in the LM1 Radiation Annual Report. 7.2.5 Results/Discussion Scheduled sampling of the calciner gas cleaning systems occurred in September 2010, November 2010, May 2011 and June 2011. Scheduled sampling was not undertaken in February 2011 due to a Processing Plant planned shutdown followed by the unplanned bogging of Calciner A. Stack testing of Calciner B in May 2011 had to be rescheduled to June 2011 due to the unplanned outage of the calciner in May when the testing was planned. Figure 7-1 shows the sampling results for both calciners since FY06. The results of the sampling (Table 7-2) indicate that emissions from Calciners A and B met the requirements of the Environment Protection (Air Quality) Policy 1994 during the reporting period. Particulate emission concentrations measured in samples collected from Calciner A decreased from an average of 74mg/Nm3 during FY10 to 64mg/Nm3 during this reporting period. Particulate emissions from Calciner B decreased from an average of 107mg/Nm3 during FY10 to 83mg/Nm3 during this reporting period. Table 7-2: Measured particulate concentrations in Calciner Emissions (mg/Nm3)

Calciner A (after mixing) Calciner B September 2010 58 136 November 2010 47 49 May 2011 86 Not conducted June 2011 Not conducted 64  Note: Environment Protection (Air Quality) Policy Limit is 250mg/Nm3

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Figure 7-1: Calciner particulate emissions sample run averages

7.3 Slimes Treatment Plant Emissions 7.3.1 Background The Slimes Treatment Plant, also referred to as the Gold Room, treats slimes generated during the electro-refining of copper anodes to produce ingots of gold and silver. This occurs inside a secure building with fume and emissions extraction provided by one of three systems; either the roaster scrubber system, the nitrogen oxides (NOx) scrubber system or general building ventilation. The roaster scrubber principally treats off-gas from the various roaster and gold and silver furnaces via a high pressure impaction scrubbing system with subsequent emission to atmosphere. The NOx gas cleaning system treats fume from the electroplating and aciding processes via sodium sulphide (Na2S) treatment, followed by scrubbing and emission to atmosphere. The general building ventilation uses positive pressure created through constant air-conditioning to remove fume via louvres. 7.3.2 Purpose To monitor emissions of particulates from Slimes Treatment Plant. 7.3.3 Deliverable(s) Compliance with the emission limits and requirements of EPA Licence 1301 and the Environment Protection (Air Quality) Policy 1994. 7.3.4 Method The impact of specific emissions on air quality is assessed through monitoring the compliance of processes with the emission limits specified in the Environment Protection (Air Quality) Policy 1994. Particulate emissions from the Slimes Treatment Plant are measured on a biannual basis by isokinetic sampling, where possible, depending upon process reliability and plant availability. Any measurement above 100mg/Nm3 is investigated and reported to EPA Regulation and Compliance within one working day.

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7.3.5 Results/Discussion Particulate sampling of the Roaster scrubber off-gas was undertaken in December 2011. The final results for particulates were 127mg/Nm3, which is above the 100mg/m3 licence condition under EPA Licence 1301. This was due to the fan being operated in manual mode which decreased the scrubber efficiency. Further stack testing which was conducted in February 2011 returned particulate results of 54mg/Nm3, which is below the 100mg/m3 licence condition under EPA Licence 1301.

7.4 Ambient Sulphur Dioxide (SO2) 7.4.1 Background

The principal point sources of SO2 at Olympic Dam are Smelter 2 and the Acid Plant. Small quantities of SO2 are also emitted from diffuse sources (e.g. process vessels). In accordance with EPA Licence 1301 Conditions (305-139), (305-140) and (305-141), Olympic Dam conducts an ongoing assessment of SO2 generation, dispersion and ambient concentration. 7.4.2 Purpose

To monitor the impact of SO2 emissions on ambient air quality. 7.4.3 Deliverable(s)

Compliance with the ground level SO2 concentration requirements of the Ambient Air Quality NEPM at Olympic Dam Village and Roxby Downs Township. 7.4.4 Method

Modelling of the annual average SO2 ground level concentration, 24-hour maximum and one-hour maximum SO2 ground level concentrations are completed using a South Australian EPA-approved computer dispersion model. Modelling is undertaken following any emission event likely to result in an exceedance of the NEPM limits and on a monthly and annual basis. A modelled exceedance of the NEPM will be reported to EPA Regulation and Compliance within one working day of the event. Results of the dispersion modelling are presented in the monthly Notification of Emission Events report submitted to EPA Regulation and Compliance within ten working days from the completion of the month. 7.4.5 Results/Discussion The results of the dispersion modelling for the reporting period indicate that no exceedance of the NEPM for ambient air quality for SO2 occurred over Olympic Dam Village or Roxby Downs Township (Figure 7-2, Figure 7-3 and Figure 7-4).

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6645

6640

1.00

6635

0.80

Smelter 6630

0.60

6625 Olympic Dam Village 0.081ppm

0.40

6620

0.20 Roxby Downs 0.023ppm 6615

0.00

6610

670 675 680 685 690 695

Note  NEPM Limit 0.2ppm over Olympic Dam Village and Roxby Downs Township.

Figure 7-2: Modelled maximum 1-hour average ground level SO2 concentration, FY11

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6645

6640

0.120

6635 0.100

Smelter 6630 0.080

0.007ppm 6625 Olympic Dam Village 0.060

0.040 6620

Roxby Downs 0.002ppm 0.020 6615

0.000

6610

670 675 680 685 690 695

Note  NEPM Limit 0.08ppm over Olympic Dam Village and Roxby Downs Township.

Figure 7-3: Modelled maximum 24-hour average ground level SO2 concentration, FY11

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6645

6640 0.0045

0.0040 6635 0.0035

Smelter 6630 0.0030

0.0025

6625 Olympic Dam Village <0.001ppm 0.0020

0.0015 6620 0.0010

Roxby Downs <0.001ppm 6615 0.0005

0.0000

6610

670 675 680 685 690 695

Note  NEPM Limit 0.02ppm over Olympic Dam Village and Roxby Downs Township.

Figure 7-4: Modelled average annual ground level SO2 concentration, FY11

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7.5 Fugitive Particulate 7.5.1 Background Many activities undertaken at Olympic Dam generate some level of fugitive particulate emission, despite efforts to minimise these emissions. Particulate emissions are monitored using a passive dust sampling network to determine dust deposition rates and concentrations of Uranium-238 (238U) contained within the dust. 7.5.2 Purpose To monitor dust deposition rates and concentration of 238U contained within deposited dust. 7.5.3 Deliverable(s)  Characterise the annual dispersion and deposition of particulates.  Characterise the annual dispersion and deposition of 238U contained within deposited particulates. 7.5.4 Method Particulate and 238U deposition rate dispersion profiles are generated and analysed to assess the impact of airborne particulate on ambient air quality. Fourteen passive dust deposition monitoring sites have been established radiating out from the operation and at background locations. Samples are collected every month and analysed for the total quantity of particulates. Six monthly composite samples are analysed for 238U activity. From these values, dust and 238U deposition rates are calculated and compared annually to previous monitoring results to assess trends. During annual flora monitoring a visual inspection of limestone dust deposition is also assessed at specific monitoring sites. The coverage of limestone on the soil surface is scored based on six rankings from no dust deposition evident to between 81% and 100% of the surface covered with limestone dust. These scores represent 4 categories of dust deposition; undetectable, detectable, high or extreme (Table 7-3). These categories are then modelled to provide a distribution of dust deposition surrounding the operations. Refer to Figure 6-1 for the sampling sites. Table 7-3 Classification of limestone dust deposition on ground surfaces

Symptom Rank score Symptoms classification of symptom category 0 No dust deposition evident Undetectable 1 Between 1 and 20% of surface covered with limestone dust 2 Between 21% and 40% of surface covered with limestone dust Detectable 3 Between 41% and 60% of surface covered with limestone dust 4 Between 61% and 80% of surface covered with limestone dust High 5 Between 81% and 100% of surface covered with limestone dust Extreme

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7.6 Results/Discussion A map detailing the passive dust monitoring site locations and numbers is shown in Figure 7-5. The average dust dispersion and deposition map for FY11 was developed as specified and is shown in Figure 7-6. Dust deposition rates at increasing distances south from site towards Roxby Downs are shown monthly in Figure 7-7. This supports the previous suggestion that there is distinct seasonal variation in dust deposition rates throughout the year. Samples were not collected in January, due to excessive rain and poor road conditions. Figure 7-8 shows historic dust deposition rates south of the operation on an annual basis. The results for FY11 are significantly lower when compared with dust deposition rates from the last reporting period due to the dust storms that occurred in FY10. Dust deposition results for PD13 however, are slightly higher when compared to previous year’s results at these locations. With the exception of PD13, the results indicate similar dust deposition rates to previous reporting periods, excluding FY10. Figure 7-9 shows the 238U deposition rate at all sites for FY11. Figure 7-10 indicates that 238U deposition at most sites recorded lower results than previous reporting periods in line with the reduced dust deposition rates. PD13 and PD14 sample points closest to the townships, returned 238U results below the detection limit. The only site recording a significant increase in 238U deposition was PD8, however the increase was not observed at the nearby PD7 site and the result is suspected to be sample contamination. Limestone dust deposition was detectable in the area immediately around the backfill and quarry again in FY11 (Figure 7-11). The modelled area of detectable dust has decreased however when compared to FY10 and did not encompass areas with a ‘high’ or ‘extreme’ impact (Table 7-4). The distribution is very similar to that observed in FY10 with an overall slight decrease, which is attributed to the substantial rainfall that occurred in 2010.

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Figure 7-5: Passive dust monitoring site locations

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Figure 7-6: Annual passive dust deposition rates measured at monitoring sites, FY11

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400

350

300 /day) 2 250

200

150

Dust (mg/m deposition 100

50

0 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun

PD10 PD11 PD12 PD13 PD14

Figure 7-7: Dust deposition rate by month at sites south of Olympic Dam

900

800

700

600 /day) 2

500

400

300 Dust deposition (mg/m deposition Dust

200

100

0 FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 FY10 FY11

PD10 PD11 PD12 PD13 PD14 Figure 7-8: Annual dust deposition rate for sites south of Olympic Dam

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Figure 7-9: Annual 238U deposition rates measured at monitoring sites, FY11

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100

90

80

70 /day) 2 60

50

40

U deposition (mBq/m 30 238

20

10

0 FY01 FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 FY10 FY11

PD10 PD11 PD12 PD13 PD14 Figure 7-10: Annual 238U deposition rate by site Table 7-4: Modelled impact footprint for limestone dust deposition and change FY10-FY11 (areas modelled to the nearest 50 ha)

Surface area modelled (ha) Soil deposition FY08 FY09 FY10 FY11 Change category Undertaken in Undertaken in Undertaken in Undertaken in FY10- September August September October FY11 Total footprint 1,050 1,050 800 200 -600 Detectable 1,050 1,050 800 200 -600 High 0 0 0 0 0 Extreme 0 0 0 0 0

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6638000

6636000 Borefield Road Borefield

6634000

6632000 North 6630000 Special Mining Lease

6628000

6626000

6624000

672000 676000 680000 684000 688000 East

Datum: GDA94 Legend Dust deposition class

Pr ojecti on: MGA94 Undetectable Operation site feature, roads Detectable and boundaries High Zone: 53 Extreme

Figure 7-11: Modelled distribution of limestone dust deposition in FY11

7.7 Raise Bore Ventilation Shaft Emissions 7.7.1 Introduction Raise bores are required to ventilate the underground mine. Emissions can be produced from the raise bores, as the ventilation shafts pass through two aquifers (Arcoona Quartzite and Andamooka Limestone). Groundwater flows passively into the unlined raise bores during normal operation, where it may be collected by the updraft of air and subsequently emitted at the surface as saline aerosols. 7.7.2 Purpose Monitor emissions of saline aerosols from the raise bores. 7.7.3 Deliverable(s) Characterise the dispersion and deposition of saline aerosol emissions around the raise bores. 7.7.4 Method A system of 26 salt deposition monitoring jars are located within the vicinity of the northern upcast raise bores, extending 3 km to the north. Salt jars are collected monthly and analysed for sodium chloride (NaCl), from which a deposition rate is derived. Comparison with historic data enables broad trending of emission capture efficiency.

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7.7.5 Results/Discussion The results of monitoring undertaken during the reporting period are presented in Figure 7-12. Deposition rates for RB10, RB16 and RB19 have maintained historically low levels during the reporting period. Note that in January 2011, there was no data collected due to high rainfall. Salt deposition data for February 2011 is a composite of the two months. Deposition rates for RB21 increased in FY08 due to the deterioration of the mist eliminator panels. Replacement panels for this raise bore were installed at the end of FY08, leading to a decrease in emissions in FY09. Emissions for RB21 increased slightly in Q4 of FY09 due to the degradation of mist eliminator panels, which continued during the first half of FY10. The mist eliminators were replaced in January 2010 which significantly reduced aerosol emissions in February 2010. Concrete fencing was installed around the raise bore to intercept aerosol emissions, and repairs were made to five bore pumps to remove the saline groundwater before it entered the ventilation fan. These improvements have continued to keep saline aerosol emissions at a low level throughout FY11.

14000.0

12000.0

10000.0

8000.0

6000.0 Salt deposition rate (mg/m2/day) rate deposition Salt

4000.0

2000.0

0.0 Jul-07 Jul-08 Jul-09 Jul-10 Jan-08 Jan-09 Jan-10 Jan-11 Nov-07 Mar-08 Nov-08 Mar-09 Nov-09 Mar-10 Nov-10 Mar-11 Sep-07 May-08 Sep-08 May-09 Sep-09 May-10 Sep-10 May-11 RB16 RB19 RB21 RB10 RB29 RB30 Figure 7-12: Monthly average of daily salt deposition rate, at monitoring sites 100m from raise bore

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7.8 Conclusion  Isokinetic sampling of the Main Smelter Stack and Acid Plant Tail Gas stack indicated continued compliance with the requirements of EPA Licence 1301 and the Environment Protection (Air Quality) Policy 1994.  The results of sampling indicate that emissions from Calciner A and B met the requirements of the Environment Protection (Air Quality) Policy 1994.

 No exceedance of the NEPM for ambient air quality for SO2 occurred over Olympic Dam Village or Roxby Downs Township during the reporting period.  Dust and 238U deposition rates recorded during the reporting period were overall lower than those measured in previous periods due to above average rainfall throughout the year.  Salt deposition rates for RB10, RB16 and RB19 are comparable to previous reporting periods. Deposition around RB21 increased during the first half of FY11, but as a result of improvement works emissions have been significantly reduced for the remainder of the year.

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8 ENERGY USE AND GREENHOUSE GAS EMISSIONS

8.1 Energy Use 8.1.1 Background The main energy sources at Olympic Dam are purchased electricity, diesel and LPG. Other sources include coke, fuel oil, soda ash, kerosene, oil, grease, sulphur, anode paste and petrol. The largest consumers of energy at Olympic Dam are the Smelter, Mine and Mill. 8.1.2 Purpose The purpose is to monitor and report the energy efficiency of the Olympic Dam operation overall and that of each area. Reporting of this to the workforce will help drive behaviours toward energy efficiency opportunities. 8.1.3 Deliverable(s) The following energy efficiencies will be calculated and made available to site personnel through Olympic Dam’s Dashboard each month. Site wide Energy Efficiency (GJ/t material milled) Mine Energy Efficiency (GJ/t hoisted) Processing Energy Efficiency (GJ/t material milled) Smelter/Refinery Energy Efficiency (GJ/t concentrate smelted) Other Energy Efficiency (GJ/t material milled) 8.1.4 Method Energy data is obtained primarily from invoices and purchasing records. Sources are traceable in accordance with the audit requirements of the National Greenhouse and Energy Reporting Act 2007 (the NGER Act). 8.1.5 Results/Discussion Energy from liquid, solid and gaseous fuel use was calculated each month based on data provided by the Olympic Dam Supply department (sourced from invoices). Energy from electricity use was calculated based on measurements from onsite metering. Calculations were performed in accordance with NGER requirements. Energy efficiency for each plant area and overall for site was calculated monthly and made available to site personnel through Olympic Dam’s Dashboard. An example of the information shown each month is given in Error! Reference source not found.. It shows the actual results for June 2011 and the year to date result (which in this case is also the overall result for FY11). Table 8-1: Actual results of Energy Efficiency for June 2011

Area Units June 2011 June 2011 Year to Date result (Overall FY11 result)

Site wide GJ/t material milled 0.62 0.60 Mine GJ/t hoisted 0.15 0.14 Processing GJ/t material milled 0.12 0.12 Smelter/Refinery GJ/t concentrate 6.79 6.66 smelted

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Area Units June 2011 June 2011 Year to Date result (Overall FY11 result) Other GJ/t material milled 0.04 0.05

8.2 Greenhouse Gas Emissions 8.2.1 Background The main GHG emissions produced due to the Olympic Dam operation are the Scope 2 emissions from electricity generated and supplied to site. The major GHG emitting areas are the Smelter, Mill and the Mine. 8.2.2 Purpose To monitor and report GHG emissions of the Olympic Dam operation overall and that of each area. Reporting of this to the workforce will help drive behaviours toward reducing GHG emissions. 8.2.3 Deliverable(s) The following GHG emission intensities will be calculated and made available to site personnel through Olympic Dam’s Dashboard.

Sitewide Carbon Equivalent Intensity (kg CO2e/ t milled)

Mine Carbon Equivalent Intensity (kg CO2e/ t hoisted)

Processing Carbon Equivalent Intensity (kg CO2e/ t milled)

Smelter/Refinery Carbon Equivalent Intensity (kg CO2e/ t concentrate smelted)

Other Carbon Equivalent Intensity (kg CO2e/ t milled) 8.2.4 Method Calculation of GHG emissions takes into account all six groups of direct GHG listed in the Annex A of the Kyoto Protocol (United Nations, 1998) as well as in the National Greenhouse Gas and Energy Reporting Regulations 2008. Emissions of each type are weighted according to their Global Warming Potential (GWP) to give a carbon dioxide equivalent emission value in units of metric tonnes of carbon dioxide equivalent, t CO2e. The other five direct GHGs listed in the Regulations are:  Methane  Nitrous Oxide  Hydrofluorocarbons (specified)  Perfluorocarbons (specified)  Sulphur hexafluoride

Emissions of Nitrous Oxide (N2O) are unlikely from Olympic Dam’s operations. Hydrofluorocarbons (CHF2FCF3) are negligible and perfluorocarbons (CF4 and C2F6) apply mainly to aluminium smelters and thus do not apply to Olympic Dam. Sulphur hexafluorides (SF6) are also negligible. Various indirect GHGs are also recorded in Olympic Dam’s reporting process, such as carbon monoxide (CO), oxides of nitrogen (NOx), oxides of sulphur (SOx), and Non- methane Volatile Organic Compounds (NMVOCs), but since these have no GWP associated with them, they are not used in the calculation of carbon dioxide equivalent emissions.

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All calculations and data sources are traceable in accordance with the audit requirements of the National Greenhouse Gas and Energy Reporting Act 2007. All emission factors are aligned with NGER guidelines. 8.2.5 Results/Discussion Greenhouse gas emissions from energy (liquid, solid and gaseous fuel use) was calculated each month based on data provided by the Olympic Dam Supply department (sourced from invoices). Greenhouse gas emissions from electricity use were calculated based on measurements from onsite metering. Calculations were performed in accordance with NGER requirements. Greenhouse gas emission intensities (carbon equivalent intensities) for each plant area and overall for site were calculated monthly and made available to site personnel through Olympic Dam’s Dashboard. The FY11 year to date was also given. An example of the information shown each month is given in Table 8-2. It shows the actual results for June 2011 and the year to date result (which in this case is also the overall result for FY11). Table 8-2: Actual results of Carbon Equivalent Intensity for June 2011

Area Units June 2011 June 2011 Year to Date result (Overall FY11 result)

Site wide kg CO2e/ t material 89 86 milled

Mine kg CO2e/ t hoisted 20 21

Processing kg CO2e/ t material 26 26 milled

Smelter/Refinery kg CO2e/ t 817 630 concentrate smelted

Other kg CO2e/ t material 5 6 milled

8.3 Conclusion  Site energy use and greenhouse gas emissions (carbon equivalent intensities) were calculated monthly during FY11. The monthly and year to date results were communicated to site personnel through Olympic Dam’s dashboard.

 The site wide performance for FY11 was 0.60 GJ/t material milled and 86 kg CO2e/t material milled

 The Mine area performance for FY11 was 0.14 GJ/t material hoisted and 21 kg CO2e/t material hoisted  The Processing area performance for FY11 was 0.12 GJ/t material milled and 26 kg CO2e/t material milled  The Smelter/Refinery area performance for FY11 was 6.66 GJ/t concentrate smelted and 630 kg CO2e/t concentrate smelted  The performance for the remainder of the operation for FY11 was 0.05 GJ/t material milled and 6 kg CO2e/t material milled

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9 RADIATION DOSE TO MEMBERS OF THE PUBLIC MONITORING PROGRAM

9.1 Dose to Members of the Public 9.1.1 Background The primary emission source of environmental radiation exposure from Olympic Dam is radon, with ingrowth of radon decay products. Radon is emitted from both point and fugitive sources. Point sources include ventilation shafts (raise bores) and some process stacks. Fugitive releases of radon may occur from mineral processing and materials handling activities as well as from ore stockpiles and the tailings storage facility. Airborne dust containing radionuclides is emitted from the operation. Olympic Dam has consistently operated in a manner that limits annual radiation dose to members of the public from operational activities to less than a small fraction of the 1mSv/y limit. 9.1.2 Purpose To conduct radon decay product monitoring and Radionuclides in Suspended Particulate Matter for the purpose of calculating radiation dose to members of the public. 9.1.3 Deliverable(s)  Calculation and assessment of annual radiation doses to the critical group i.e. members of the public with full time occupancy in Olympic Dam Village and members of the public with full time occupancy in Roxby Downs.  Reporting of results in the annual Environmental Management and Monitoring Report (EMMR) and the Radiation Protection Annual Report - Licence Number LM1. 9.1.4 Method

The effective dose attributable to radon decay products (EDERn) and radionuclides in dust (EDED) are calculated and summed to produce the total effective dose (i.e. the annual radiation dose to members of the public). Radon Decay Products Radon decay product concentrations are measured and recorded on a ten minute basis at powered monitoring stations located at Roxby Downs (RDS) and Olympic Dam Village (ODV) (Figure 8-1). Meteorological data is acquired from the Bureau of Meteorology weather station equipped with wind speed and direction sensors. This is located in the vicinity of the ODV monitoring station at the Olympic Dam Airport and is representative of meteorological conditions in the operational area. The radon decay product concentration measurements are captured by data loggers and are regularly downloaded to the computer network for storage in a database. The natural background concentrations of radon decay products at ODV and RDS and the concentrations attributable to the operation are calculated using wind direction to differentiate the location of the sources. The concentration of radon decay products measured at ODV and RDS when the wind is blowing from within their respective operational sectors (i.e. comes from the vicinity of the operation) (Figure 1-1) is deemed to be comprised of background plus operationally-related radon decay products. Alternately, when the wind is blowing from directions other than the operational sectors, it is designated as coming from the background sectors, and the measured concentration of radon decay products is deemed to be entirely due to natural background sources.

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Figure 9-1: Environmental Radiation Monitoring Sites

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The annual radon decay product concentration attributable to the operation is calculated at ODV and RDS by:  Subtracting the monitoring site’s mean background sector concentration from the site’s mean operational sector concentration and then;  Multiplying the residual by the fraction of time that wind direction was within the monitoring site’s operational sector. A threshold wind speed (1m/s) is used to exclude data from the above calculation because concentrations measured at RDS and ODV below this wind speed are unlikely to be influenced by radon decay products originating from the operation, and the wind direction sensor nears the limit of its ability to accurately determine direction at wind speeds below this value.

BHP Billiton Olympic Dam estimates the effective dose from radon decay products EDERn (in mSv/y) using the following equation:

EDERn = R x t x DCF where R is the residual radon decay product concentration (mJ/m3), t is the total number of hours per year (h/y) and DCF is the dose conversion factor applicable for non-working residents living at home and is equivalent to 1.1mSv per mJ.h.m-3 (ICRP 1996a). Radionuclides in Suspended Particulate Matter The suspended particulate matter monitoring program (using high volume samplers fitted with PM10 size-selective inlets) yields fortnightly PM10 samples from ambient air for each monitoring site. The PM10 size-selective inlet is used to ensure only dust of the inhalable size fraction is sampled. Background radionuclide concentrations have been measured by a high volume air sampler fitted with PM10 size-selective inlet at the Roxby Downs Homestead (RDH) located on Roxby Downs Station, approximately 30 kilometres SSW of the operation. Analysis of long-lived radionuclide concentrations in dust is undertaken on samples collected from each of the three sites. The calculation of dose to members of the public related to the operation involves subtracting the derived background concentrations measured at RDH from the measured RDS and ODV results. The dose estimation methods used are provided in ICRP 71, and the DCFs used for each uranium series radionuclide are specified in ICRP 72. The mean concentration of radionuclides in dust attributable to the operation is multiplied by the number of hours of exposure per year, the standard persons breathing rate, and a dose conversion factor (DCF) that converts the concentration of inhaled radionuclide in dust into effective dose for that radionuclide (EDR). The formula used is:

EDR = C x h x B x DCF where C is the mean annual concentration (Bq/m3), h is the number of hours of exposure per year, B is the breathing rate (m3/h) and DCF is the dose conversion factor (in mSv/Bq) for the specific radionuclide.

The effective dose from dust (EDD) is then the sum of the effective dose for each of the long lived radionuclides.

EDD = Σ EDR

Total Effective Dose Equivalent

By summing the two effective dose equivalents, one due to radon decay products (EDERn) and the other due to radionuclides in dust (EDED), the total effective dose equivalent ED (in units of mSv/y) for RDS and ODV is obtained.

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9.1.5 Results/Discussion Radon Decay Products Monthly radon decay product averages for the reporting period are shown in Figure 9-2, together with the five year rolling average.

50

45

40 ) 3 35

30

25

20

15 Radon concentration (nJ/m concentration Radon

10

5

0 Jul-10 Oct-10 Apr-11 Jun-11 Jan-11 Mar-11 Feb-11 Nov-10 Aug-10 Dec-10 Sep-10 May-11

RDS Monthly Average ODV Monthly Average RDS 5 Year Rolling Average ODV 5 Year Rolling Average

Figure 9-2: FY11 radon decay product monthly averages, including five-year trends The total doses to members of the public at RDS and ODV due to radon progeny (including background) were 0.166mSv/yr and 0.134mSv/yr respectively. Both results were lower compared to previous reporting periods. The major source of error in these estimates arises from the natural variation of the background radon decay product concentration. The standard errors associated with these measurements for the reporting period were 0.002mSv/yr and 0.001mSv/yr respectively. A unit of measurement error was found in the standard error calculation process and has been corrected for this report. When background concentrations were subtracted using the method outlined in Section 9.1.4, the mean calculated doses to members of the public attributable to the operation were 0.009mSv/yr at RDS and 0.006mSv/yr at ODV. Error analysis conducted on 11 years of monitoring data (Crouch et al. 2003) indicates that the radon progeny component of the dose calculation methodology is subject to a minimum detection level of approximately 0.040mSv. That is, it can only determine dose due to radon progeny from the operation above that value. A result below this detection level represents a dose less than 4% of the legislated exposure limit of 1mSv/yr. The dose to members of the public due to operation-related radon progeny at both RDS and ODV were found to be close to or below the detection level (0.040 mSv). Historic monitoring data suggests that there is little operation-related radon progeny concentration at these monitoring sites. Calibration of the radon prism monitors was undertaken in August 2010 and March 2011. There were a number of periods throughout the year where the radon prisms were unavailable for sampling due to technical problems or in transport to and from the calibration facility.

RADIATION DOSE TO MEMBERS OF THE PUBLIC MONITORING PROGRAM Page 117 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Radionuclides in Dust Monthly concentrations of the long-lived radionuclides, 238U, 230Th, 226Ra, 210Pb and 210Po for the previous five years, are shown in Figure 9-3, Figure 9-4, Figure 9-5, Figure 9-6 and Figure 9-7. The monthly dust (TSP/PM10) concentration is shown in Figure 9-8. It is important to note that from FY08 onwards, data is from High Volume Air Samplers (HVAS) using PM10 size selective heads, which sample only the respirable dust fraction. Previous years’ data is from TSP sampling heads. The data from FY08 onwards is therefore not directly comparable with previous years, although comparative analysis of the TSP and PM10 data during an eight month overlap period indicated that:

 Approximately 40-50% of the dust present at RDS and ODV reports as PM10, so results obtained using the PM10 sampler are expected to be approximately half of the results using the TSP samplers;  238U, 230Th and 226Ra radionuclides are distributed fairly equally between sub 10µm and larger dust particles, so results obtained using the PM10 sampler are expected to be approximately half of the results using the TSP samplers; 210 210  Effectively all Pb and Po are present in the PM10 dust fraction. TSP and PM10 data would therefore be fairly comparable for these isotopes.

20

15 ) 3

10 Activity (uBq/m

5

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

238 Figure 9-3: U concentration for the previous 5 years (in TSP and PM10)

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20

18

16

14 ) 3 12

10

8 Activity (uBq/m

6

4

2

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

230 Figure 9-4: Th concentration for the previous 5 years (in TSP and PM10)

35

30

25 ) 3 20

15 Activity (uBq/m

10

5

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

226 Figure 9-5: Ra concentration for the previous 5 years (in TSP and PM10)

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700

600

500 ) 3 400

300 Activity (uBq/m

200

100

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

210 Figure 9-6: Pb concentration for the previous 5 years (in TSP and PM10)

180

160

140

120 ) 3

100

80 Activity (uBq/m 60

40

20

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

210 Figure 9-7: Po concentration for the previous 5 years (in TSP and PM10)

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300

250 ) 3 200

150

100 Dust Concentration(ug/m Dust

50

0 Jul-06 Jul-07 Jul-08 Jul-09 Jul-10 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09 Apr-10 Oct-10 Apr-11 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

RDS ODV

Figure 9-8: Total TSP and PM10 concentration for the previous 5 years The region continued to experience above average rainfall during FY11 which has resulted in the recording of some of the lowest PM10 and radionuclide concentrations in recent history. The PM10 results did however follow a seasonal trend throughout the warmer months. Analysis error estimates have also been presented in Figure 9-3 through to Figure 9-7 for data from January 2009 to be consistent with recent quarterly environment reports. Several of the radionuclide activity concentrations were below analysis error during FY11. The estimated doses to members of the public at RDS and ODV, due to radionuclides in dust, including background, were 0.0025mSv/yr and 0.0027mSv/yr respectively. When background is subtracted from the above figures, the mean doses to members of the public at RDS and ODV, due to radionuclides in dust and attributable to the operation, were 0.0003mSv/yr and 0.0001mSv/yr respectively. The operational contribution to dose was lower than in previous years as some radionuclide activities were below the activities recorded at the background site. This was due to the above average rainfall causing a reduction in PM10 and radionuclide concentrations. Error analysis previously conducted on four years of data indicates that the dose calculation methodology is subject to a minimum detection level of approximately 0.0080mSv (>0.01%). That is, it can only determine dose due to radionuclides in dust from the operation above that value. Thus, the dose to members of the public due to radionuclides in dust at RDS and ODV are both below the detection limit (0.0080mSv).

RADIATION DOSE TO MEMBERS OF THE PUBLIC MONITORING PROGRAM Page 121 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Total Dose to Members of the Public The total estimated doses to members of the public at RDS and ODV contributed by the operation were 0.009mSv/yr and 0.006 Sv/yr respectively. The estimated mean dose to members of the public at RDS and ODV attributable to operations at Olympic Dam are sufficiently masked by the natural background variations to be below the detection limits. Thus, the maximum effective dose at both RDS and ODV is below the detection limit of 0.048mSv/yr for the combined dose from radionuclides in dust and radon decay products. This effective dose to members of the public is less than 5% of the legislative limit of 1mSv/yr and less than 10% of the operations internal working limit of 0.5mSv/yr (Figure 9-9).

1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40 Dose equivalent equivalent (mSv/yr) Dose 0.30

0.20

0.10

0.00 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 FY05 FY06 FY07 FY08 FY09 FY10 FY11

RDS ODV Detection Limit Legislative Limit

Figure 9-9: Total effective dose

9.2 Conclusion  The dose to members of the public due to operation-related radon progeny at both RDS and ODV were below the detection level of 0.040mSv.  The dose to members of the public due to operation-related radionuclides in dust at both RDS and ODV were below the detection limit of 0.008mSv.  An effective dose to members of the public of less than the detection limit of 0.048mSv/year was calculated when background dose calculations were subtracted from measured doses. This value was less than 5% of the legislative limit of 1mSv/year.

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10 WASTE MONITORING PROGRAM

10.1 Tailings Storage Facility (TSF) 10.1.1 Background Tailings generated from the hydrometallurgical plant are pumped as slurry from the tailings disposal surge tanks to the TSF. The tailings are discharged onto the TSF cells via spigot off-takes from the tailings distribution pipework located at the crest of the perimeter embankments of each cell of the TSF. Other miscellaneous hazardous or low level radioactive wastes are also delivered to the TSF as a solid, slurry or liquid. External perimeter embankments of the TSF are constructed using clayey soil, sand, crushed rock and tailings. The outer face is covered with rock armouring for erosion protection and the crest is covered with a crushed road base material to provide a trafficable surface. Design, construction and operation ensure stability under static and seismic loading minimises seepage of liquor as far as practicable and minimises erosion on the outer face. 10.1.2 Purpose Monitor the operation and performance of the Tailings Storage Facility to identify potential for adverse environmental impact on soil and groundwater quality. 10.1.3 Deliverables  Monitor the size and location of the supernatant liquor ponds in each TSF cell.  Monitor the rate of rise of tailings in each TSF cell.  Review the water balance on an annual basis.  Monitor the pore pressures within tailings adjacent to the external walls of the TSF.  Fulfil requirements of the Groundwater Monitoring Program. 10.1.4 Method The monitoring of tailings deposition is conducted in accordance with the Tailings Retention System Technician Daily Routine (BHP Billiton Olympic Dam 2010f) and the Tailings Management Plan (BHP Billiton Olympic Dam 2010g). The Tailings Management Plan incorporates:  Detailed description of the Tailings Retention System (TRS)  5 year rolling production plan  50 year tailings storage plan  50 year tailings storage financial plan  Operating plan  Monitoring plan  Licensing plan  Decommissioning and closure plan Assessment of the size and location of the supernatant ponds is conducted weekly by visual inspection (BHP Billiton Olympic Dam 2010f). A more detailed estimate of the location and area of the supernatant liquor pond in each TSF cell are carried out monthly and reported to regulatory agencies quarterly. Periodic capture of satellite photography provides accurate size and pond location. Annual overhead aerial photography allows the accurate calculation of pond area. Oblique aerial photography is performed at a nominal monthly interval subject to weather and aircraft availability.

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The rate of rise of tailings is determined using tailings deposition records and surveys of the tailings beach at the perimeter of each TSF Cell prior to each tailings embankment raise. An annual water balance is calculated from monthly data for the TSF to assess the ongoing liquor disposal requirements. Data used includes estimates of tailings production and average tailings slurry density, daily volumes of supernatant liquor decanted to the EPs, daily records of rainfall and pan evaporation, flows into and within the EPs and daily liquor levels in the EPs. An annual operational audit is performed for the TSF by an external tailings consultant. The annual audit includes a geotechnical assessment of the facility and a water balance. Standpipe and vibrating wire piezometers are monitored on a regular basis to assess the pore pressures within the tailings adjacent to the embankments of the TSF. Piezometers used include standpipe, pneumatic and vibrating wire piezometers. Additional or replacement piezometers are installed from time to time as required. 10.1.5 Results/Discussion Management of Supernatant Ponds The combined area of the supernatant ponds was within target pond area of 3.0ha per cell for TSF Cells 1, 2, and 3 during July 2010 and December 2010 but was above for the remainder of FY11. The area of the supernatant ponds was above target of 13.0ha for Cell 4 for the entire reporting period (Figure 10-1).

50

45

40

35

30

25 Area (ha) 20

15

10

5

0 Jul-10 Jul-09 Apr-11 Apr-10 Oct-10 Oct-09 Jan-11 Jun-11 Jan-10 Jun-10 Mar-11 Mar-10 Feb-11 Feb-10 Nov-10 Nov-09 Dec-10 Dec-09 Aug-10 Aug-09 Sep-10 Sep-09 May-11 May-10

TSF 1-3 Target TSF 1-3 TSF 4 Target TSF 4

Figure 10-1: TSF Supernatant Pond areas The combined area of the supernatant ponds on TSF Cells 1–3 varied between 7.6ha and 25.0ha over the reporting period with an average of 15.6ha, an increase of 84% from the previous year’s average of 8.5ha.

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The supernatant pond area on TSF Cell 4 varied between 22.6ha and 42.5ha over the reporting period with an average of 30.5ha, an increase of 68% from the previous year’s average of 18.2ha. The increase in supernatant pond area over the reporting period was mainly due to significant rainfall, however low tailings densities and EP2, EP3A and EP3B being out of service and not available for tailings liquor also contributed. A satellite photograph of the TRS, taken in early July 2011 is shown in Figure 10-2.

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Figure 10-2: TRS aerial photograph – July 2011

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Tailings Density The return to full production following an incident at the Clark Shaft in October 2009 can be seen in the net tailings density (tailings density after allowance for liquor return) shown in Figure 10-3, which shows a significant decline in net tailings density until it was recommissioned in May 2010. During FY11, the net tailings density rose steadily from 47.64% in July 2010 to 50.89% in June 2011, with the average over the reporting period being 49.16%. The average pumped density over the reporting period was 46.72%. The net tailings density is the adjusted tailings density after liquor returned to the plant is subtracted from liquor contained in pumped tailings and is a measure of the liquor in the tailings stream that needs to be stored or evaporated.

1,000,000 100

900,000 90

800,000 80

700,000 70 Slurry Density (% Solids)

600,000 60

500,000 50

400,000 40 Solids (Tonnes), Liquor (Kilolitres) (Kilolitres) Liquor

300,000 30

200,000 20 No solids to TSF during Jan 2010 100,000 10

0 0 Jul-09 Jul-10 Oct-09 Apr-10 Oct-10 Apr-11 Jun-10 Jan-10 Jun-11 Jan-11 Mar-10 Mar-11 Feb-10 Feb-11 Nov-09 Nov-10 Aug-09 Dec-09 Aug-10 Dec-10 Sep-09 Sep-10 May-10 May-11

Solids Liquor Net Tailings Slurry Density Tailings Slurry Density

Figure 10-3: Tailings Solids, Liquor and Tailings Density as % Solids The TSF Cell 4 underdrainage system pumped a total of 51,003kL over the reporting period. The average pumping rate on days that the pump was operating was 174kL/day and at the end of the reporting period the average daily pumping rate was approximately 150kL/day. The corresponding average daily pumping rate at the end of the previous reporting period was 200kL/day. Figure 10-4 shows the pumping rate over the last two years.

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1000

900

800

700

600

kL/d 500

400

300

200

100

0 Jul-09 Jul-10 Apr-10 Apr-11 Oct-09 Oct-10 Jun-10 Jun-11 Jan-10 Jan-11 Mar-10 Mar-11 Feb-10 Feb-11 Nov-09 Nov-10 Aug-09 Aug-10 Dec-09 Dec-10 Sep-09 Sep-10 May-10 May-11 Figure 10-4: TSF Cell 4 Underdrainage Pumping Rate Cycling of Active Tailings Discharge Locations The location of supernatant ponds is managed such that ponding of supernatant against perimeter embankments is minimised by practices such as rotation of spigot (deposition) points. Tailings deposition is managed to ensure cycling of tailings deposition around each tailings cell. The locations of tailings deposition in each cell are monitored daily. Notable operational changes during the reporting period include:  Tailings deposition at 9.25Mt/yr, an increase of 108% compared to the FY10 reporting period, due to the return to full production rates following recommissioning of the Clark Shaft.  Continued raising of the walls of TSF Cells 1–3 in 1 metre lifts as follows:  Fifteenth lift of TSF Cell 2 was completed to RL 128.5mAHD in September 2010  Fifteenth lift of TSF Cell 3 was completed to RL 128.5mAHD in December 2010  Sixteenth lift of TSF Cell 1 was completed to a height of RL129.5mAHD in March 2011  Sixteenth lift of TSF Cell 2 was completed to a height of RL 129.5mAHD in May 2011  Continued raising of the walls of TSF Cell 4 in 1 metre lifts as follows:  Fourteenth lift of the TSF Cell 4 south wall was completed to RL 122.0mAHD in December 2010  Fourteenth lift of the TSF Cell 4 west wall was completed to RL 122.0mAHD in January 2011  Fourteenth lift of the TSF Cell 4 north wall was completed to RL 122.0mAHD in February 2011

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Rate of Rise of Tailings The rate of rise of tailings has been limited to 2m/annum or less for all cells to ensure consolidation of tailings material. During the reporting period, tailings were distributed to TSF Cells 1–4 with an average rate of rise of the perimeter tailings beach of 1.6m/annum. Tailings delivery to TSF Cell 4 prior to 2003 was biased towards the internal east wall as the availability of this wall for tailings deposition was largely unaffected by wall-raising activities, resulting in a higher beach level when compared to the external wall. A plan was initiated in 2003 to address this issue and bias the tailings delivery to TSF Cell 4 external walls. Good progress has been achieved during the current reporting period with the difference in elevation (between the east wall and other walls) decreasing by 0.31m. No significant impacts have resulted from the difference in height between the internal east wall and external walls of TSF Cell 4. This issue will continue to be addressed by the program of reduced deposition to the east wall, gradually bringing it in line with other walls. The elevation of tailings in the cells illustrated on Figure 10-5 gives an indication of the rate of rise of the perimeter tailings beaches. The rate of rise in TSF Cells 1, 2, 3 and 4 were all less than or equal to the target of 2m/annum. The rates of rise for TSF Cells 1, 2 and 3 were 2.0, 1.7 and 1.4m/annum respectively, and for TSF Cell 4 the average rate of rise was 1.6m/annum for external walls and 1.4m/annum overall.

130

128 126 124 122 120 118 116

(m AHD) 114 112 Tailings Beach Level Beach Tailings 110 108 106 104 102 100 Jun-95 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05 Jun-06 Jun-07 Jun-08 Jun-09 Jun-10 Jun-11

TSF1 TSF2 TSF3 TSF4 TSF4 East Wall

Figure 10-5: Elevation of tailings in TSF cells TSF Water Balance The water balance for TSF Cells 1–4 indicates that the calculated evaporation factor to dispose of unaccounted liquor is 51% of the Class A pan evaporation rate (56% for TSF Cells 1–3 and 46% for TSF Cell 4). The results indicate that during the reporting period the TSF had the capacity to dispose of excess liquor by evaporation. It is noted that the unaccounted liquor also includes seepage from beach areas.

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Unaccounted liquor includes input liquor shown in Figure 10-6 (tailings liquor, rainfall, flushing liquor, and the decrease in supernatant pond inventory) minus liquor retained in tailings (moisture content assumed of 30% by weight), liquor decanted to evaporation ponds, and estimated seepage from (supernatant liquor) ponds. Output liquor is equal to input liquor and is shown in Figure 10-7. Seepage from pond areas has been calculated based on the average supernatant pond areas for TSF Cells 1-4 (26.7ha) and an assumed tailings permeability (2x10-8 m/s). Liquor retained in tailings was assumed to be 30% of the weight of tailings solids deposited based on previous testing of in-situ tailings. Note, flushing liquor is liquor pumped out of the evaporation ponds to the TSF for the purpose of flushing lines or to enhance evaporation. The water balance shows 9% of liquor input due to rainfall compared to 14% in the previous reporting period. Rainfall measured for the reporting period was 278.4mm compared to the previous reporting period of 251.4mm and a median rainfall of 136.2mm. The increased volume of rainfall input, with the majority falling in February 2011, combined with increased tailings deposition resulted in a significant increase in the proportion of liquor decanted to evaporation ponds and an increase in the proportion of liquor retained in tailings.

Decrease in TSF Pond Flushing Liquor Inventory 0% 1%

Rainfall 9%

Decant to EP's Evaporation 27% 44%

Liquor with Tailings 90% Retained in Tails 26%

Seepage from Ponds 3%

Increase in TSF Pond Inventory Liquor Inputs [ TOTAL 10788.324 ML] 0% Liquor Outputs [ TOTAL 10788.324 ML] Figure 10-6: TSF Cells 1 – 4 Liquor Figure 10-7: TSF Cells 1 – 4 Liquor Balance – Inputs, FY11 Balance – Outputs, FY11 Pore Pressures The perimeter of the TSF is monitored on a regular basis to identify any additional features which develop and to record changes to existing features. Most of the features observed are minor and the increased moisture is likely to be the result of a localised area of increased permeability and higher phreatic surface as the height of the TSF increases over time. A network of piezometers has been installed to monitor pore pressure distributions within and adjacent to perimeter embankments of the TSF to ensure that adequate factors of safety are maintained for the stability of embankments.

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A number of areas of increased moisture have been observed around the perimeter of the TSF. Four new areas (locations 13A, 13B, 15 and 16) have been identified over the reporting period. All other areas have been reported previously. The areas are shown on Figure 10-8 and are listed below in Table 10-1. Table 10-1: List of perimeter features including their location, discovery date and status

Location Location Discovery Summary of Status Number Date 1 East wall of TSF Cell 1 at the 2008 Damp, no change from previous toe reporting period 2 East wall of TSF Cell 1 at the 2008 Liquor intercepted in trench, no toe and pipe corridor change in dampness from previous reporting period. There has been an increase in the average daily flow rate from 4 to 6m3/day over the reporting period. 3 South wall of TSF Cell 1 on Feb 2008 Becoming drier, no seepage flow the embankment face present. Filter Blanket now installed over area. Quality of seepage encountered during construction was found to be neutral. 4 Adjacent to the south wall of 2006 Slightly damp, no change from TSF Cell 4 previous reporting period 5 Southwest Corner of TSF Cell 2008 Slightly damp, no change from 4 on the embankment face previous reporting period 6A and West wall of TSF Cell 4 on 2008 Slightly damp, no change from 6B the embankment face previous reporting period 7 Intersection of TSF Cell 3 and Apr 2008 Beneath Cell 3-4 buttress, no change TSF Cell 4 at toe from previous reporting period 8 Intersection of TSF Cell 3 and Apr 2008 Beneath Cell 3-4 buttress, no change TSF Cell 4 on embankment from previous reporting period face 9 Toe of the west wall of TSF Apr 2008 Beneath Cell 3-4 Buttress, no change Cell 3 from previous reporting period 10 West wall of TSF Cell 4 on 2008 Dry, no change from reporting period the embankment face 11 South wall of TSF Cell 4 2008 Slightly damp, no change from adjacent to the toe of the previous reporting period dune – east of decant pipe 12 Cell 2 crest of starter 2009 Slightly damp, no change from embankment previous reporting period 13, 13A Cell 1 crest of starter 2009 13A and 13B growing in size. Liquor and 13B embankment and at toe present at surface, but no flow is present. 14 West wall of TSF Cell 4 at the 2009 Slightly damp, no change from embankment toe previous reporting period 15 South wall of TSF Cell 4 Jul 2010 Slightly damp (East of Location 11) 16 Northeast corner of Cell 3 Dec 2010 Slightly damp (North of Location 12)

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Figure 10-8: Location of perimeter features monitored regularly A brief description of selected locations and commentary on any significant changes over the reporting period is provided below. Location 3 – Cell 1 South Side – Face of Embankment An area of increased moisture content was identified in February 2008 and is shown in Figure 10-9. Investigations indicate the area is adjacent to an old causeway. A network of 18 standpipe piezometers and 7 trial vibrating wire piezometers have been installed to monitor the area. A schematic cross section for 10 of the piezometers and the 7 vibrating wire piezometers is shown in Figure 10-10 for the south side of TSF Cell 1. Hydrographs for the piezometers are shown in Figure 10-11. A steady trend with upper level piezometers shows an increasing water level in response to increased tailings deposition rates since the Clark shaft incident in October 2009. Ponded water on the surface has been tested and is neutral and low in copper and uranium indicating it could be neutralised tailings liquor or stormwater. The vibrating wire piezometers are currently out

Page 132 WASTE MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT of service due to problems with the instrument that reads the piezometers. A buttress was constructed over Location 3 during May and June 2011 to minimise the potential for piping (internal erosion through the embankment). During construction, seepage quality was tested and the results showed that the seepage was neutral.

Figure 10-9: Photo of location 3 in August 2011 showing buttress

TP45 VWP11 TP47 130 VWP12 TP44 VWP13 TP46

125 TP50 VWP7 Hydrostatic TP48 VWP8 Pressure TP51 VWP9 VWP10 Line 120 TP49

115 TP56 Elevation (mAHD) Elevation 110

TP39

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100 200 740 200 760 200 780 200 800 200 820 200 840 200 860 200 880 Northing (m)

Figure 10-10: Schematic cross section through south side of TSF Cell 1 – June 2011

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TP39 TP40 TP41 TP42 TP43 TP44 TP45 TP46 TP47 TP48 TP49 TP50 TP51 TP52 TP53 TP54 TP55 TP56 VWP7 VWP8 VWP9 VWP10 VWP11 VWP12 VWP13 Figure 10-11: TSF Cell 1 South Wall Piezometer Hydrographs Locations 7, 8 and 9 – TSF Cell 3 west /TSF Cell 4 north Liquor was observed at the toe of the west wall of TSF Cell 3 in April 2008. Installation of a permanent engineered liquor interception system was completed in March 2009 and an engineered filter and buttress was installed in June 2010. A dewatering bore was installed into the mullock starter embankment of TSF Cell 3 which has reduced the seepage rate to approximately 3kL/d (Figure 10-12).

150 140 Dewatering bore commissioned 130 13 May 2010 120

110 100 90 80 70 60

Flow (kL per Day) Seepage flow 50 reduced from 105 kL/d to 40 3 kL/d 30 20 10 0 01-Jul-08 01-Jul-09 01-Jul-10 01-Apr-09 01-Apr-10 01-Apr-11 01-Oct-08 01-Oct-09 01-Oct-10 01-Jun-08 01-Jan-09 01-Jun-09 01-Jan-10 01-Jun-10 01-Jan-11 01-Jun-11 01-Feb-09 01-Mar-09 01-Feb-10 01-Mar-10 01-Feb-11 01-Mar-11 01-Aug-08 01-Sep-08 01-Nov-08 01-Aug-09 01-Sep-09 01-Nov-09 01-Aug-10 01-Sep-10 01-Nov-10 01-Dec-08 01-Dec-09 01-Dec-10 01-May-08 01-May-09 01-May-10 01-May-11

Total Flow 14 per. Mov. Avg. (Total Flow) 91 per. Mov. Avg. (Total Flow) Figure 10-12: TSF Cell 3 daily seepage liquor flow

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Chemical analysis of the liquor is also recorded on a regular basis and is shown in Figure 10-13. During the reporting period, the concentration of U3O8 had reduced to near background levels, and the pH had increased to near neutral. However, the 14 day moving average U3O8 concentration has increased to a peak of 85 mg/l and then reducing to 40mg/l, and the pH has decreased to 4.9. Investigations into the cause of the change are currently being undertaken but it appears to be associated with an increase in flow rate following significant rainfall in February 2011.

350 7.0

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0 0.0 01-Jul-10 01-Jul-09 01-Jul-08 01-Apr-11 01-Apr-10 01-Apr-09 01-Oct-10 01-Oct-09 01-Oct-08 01-Jan-11 01-Jun-11 01-Jan-10 01-Jun-10 01-Jan-09 01-Jun-09 01-Jun-08 01-Feb-11 01-Mar-11 01-Feb-10 01-Mar-10 01-Feb-09 01-Mar-09 01-Aug-10 01-Sep-10 01-Nov-10 01-Aug-09 01-Sep-09 01-Nov-09 01-Aug-08 01-Sep-08 01-Nov-08 01-Dec-10 01-Dec-09 01-Dec-08 01-May-11 01-May-10 01-May-09 01-May-08 U308 PH 14 per. Mov. Avg. (U308) 91 per. Mov. Avg. (U308) 14 per. Mov. Avg. (PH) 91 per. Mov. Avg. (PH) Figure 10-13: TSF Cell 3 liquor analyses

Location 13A & 13B – TSF Cell 1/2 East Two areas of increased surface moisture were identified in July 2010 during regular embankment inspections. These are located within the pipe trace adjacent to Lower Valve Station 2, on the east side of TSF Cell 1/2. The moist areas were initially very small, however, they have steadily grown over the reporting period (Figure 10-14). There is liquor present at the surface, however no seepage flow is present. Piezometer TP88, located at 13A is dry. However, TP176 which is located within Cell 2, east of Location 13B, shows a head of approximated 10m above the natural surface (RL110 mAHD). This could indicate a potential flow path through an existing sand dune within the dam, which then connects to the mullock starter which forms the east wall of Cell 2. It is planned to install a seepage trench similar in design to Location 2 as a precautionary measure.

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Figure 10-14: Photograph of Location 13B looking North in July 2011 Project Progress Progress highlights of current projects are provided below:  Raising EP Embankments  2 metre wall raise to EP1  Commissioned successfully in July 2010  Stability Review  A further 9 Standpipe piezometers were installed  Stability assessment undertaken to investigate TSF Cells 1-3 potential height increase from 30m to 34m.  Design and installation of a buttress on South Wall TSF Cell 1.  TSF Cell 5  Continued construction of TSF Cell 5  Commissioning planned to commence in FY12  Tailings Disposal Upgrade  Construction of a staged upgrade commenced with commissioning of the first stage to coincide with commissioning of TSF Cell 5 East.

10.2 Evaporation Ponds (EPs) 10.2.1 Background Olympic Dam operates five EPs. The principal function is the storage and evaporation of surplus tailings liquor decanted from the TSF.

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The crests of the EPs are profiled such that there is a uniform cross fall from the outer edge to the inner edge and a constant level is maintained around the perimeter of each cell. A bund is included on the outer edge as a contingency to contain any liquor that overtops the ponds due to wind and wave action. Liquor evaporates and concentrates in the evaporation cells, resulting in precipitation of solids, principally iron sulphate. A programme has been developed to minimise the precipitation of solids and is currently being implemented. 10.2.2 Purpose  Monitor the operation and performance of the EPs to identify potential for adverse environmental impact on soil and groundwater quality.  Monitor the liquor inventory in the EPs to assess the evaporation capacity of the ponds in relation to the volume of surplus liquor reporting from the TSF and assist in the liquor management within the TRS. 10.2.3 Deliverables  Monitor the liquor level in each cell of the EPs to maintain adequate freeboard to prevent overtopping of the embankment crest.  Monitor the overall (solids and liquor) inventory in the EPs.  Conduct a liquor balance of each evaporation cell to highlight potential significant leaks.  Fulfil requirements of the Groundwater Monitoring Program. 10.2.4 Method EP levels are measured using a combination of laser, radar and manual measurements depending on the level of solids build-up in the cell and access provisions in each cell (eg stilling wells or jetty). EPs are inspected and liquor levels are recorded on a daily basis (BHP Billiton Olympic Dam 2010f). Stored volume (liquor and solids) is calculated from daily liquor level measurements to enable freeboard and overall EP (solids and liquor) inventory to be determined. A liquor balance is performed to highlight cells with potential significant leaks by comparison of the apparent evaporation from each cell of each EP. The comparison is carried out on a monthly basis and presented to regulatory agencies in a quarterly report. 10.2.5 Results/Discussion Tailings Retention System Seepage (ID 3.2) within the Environmental Management Program (BHP Billiton Olympic Dam 2010b) describes a number of management controls in place to control environmental impacts. Monitoring is conducted to assess the performance of the controls. Detection of Seepage Seepage from the ponds is identified by piezometers in and around the ponds and liquor balance calculations. The former is addressed in detail in Section 3. Figure 10-15 shows the cumulative evaporation trends for EP1 and EP2. Figure 10-16, Figure 10-17 and Figure 10-18 show the cumulative apparent evaporation trends for Evaporation Ponds 3, 4 and 5 respectively. Figure 10-19 shows the comparison of cumulative evaporation for all cells. The upper and lower bounds have been calculated using the average evaporation rate from all operational cells and applying an estimated error or variation (plus or minus) to the average value. The performance of each of the evaporation ponds is discussed in further detail below. Evaporation cells occasionally ‘dry out’ when all free liquor is evaporated, exposing the surface of the solids sludge built up in the cell. During these periods a liquor level is not

WASTE MONITORING PROGRAM Page 137 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT able to be measured and therefore the cumulative evaporation trends level out and the water balance method is no longer effective in confirming cell integrity. However, as the cell is ‘dry’ there is little if any free liquor available and therefore very little potential for significant seepage from the ‘dry’ cells. EP2 was out of service at the start of the reporting period after movement of some of the wave barriers, and was returned to service during November 2010. EP3A was out of service due to high level of precipitated solids for the entirety of the reporting period. The trend in EP3B was consistent with other fully operational cells as shown in Figure 10-19. EP3B dried out in May 2010, and is currently out of service due liner damage identified in September 2010. The trends in EP4A and EP4B were consistent with each other as shown in Figure 10-17 and with other operational cells as shown in Figure 10-19. The trends in EP5A and EP5B were consistent with each other as shown in Figure 10-18 and with other operational cells as shown in Figure 10-19. Figure 10-19 shows the comparison of cumulative evaporation for all evaporation cells. The upper and lower bounds have been calculated using the average evaporation rate from the ‘non-dry’ cells that have been fully operational during the period.

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EP1 EP2 Upper Bound Lower Bound

Figure 10-15: EP1 and EP2 Liquor Balance – cumulative apparent evaporation trends

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Figure 10-16: EP3 Liquor Balance – cumulative apparent evaporation trend

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Figure 10-17: EP4 Liquor Balance – cumulative apparent evaporation trend

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Figure 10-18: EP5 Liquor Balance – cumulative apparent evaporation trend

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CELL 1A CELL 1B CELL 1C CELL 1D CELL 2A CELL 2B CELL 2C CELL 2D CELL 3A CELL 3B CELL 4A CELL 4B CELL 5A CELL 5B Upper Bound Lower Bound

Figure 10-19: All EP Liquor Balance – cumulative apparent evaporation

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Freeboard Figure 10-20 shows the evaporation pond capacity in relation to the normal maximum operational storage capacity. Additional capacity is provided as a contingency for extreme rainfall events and allowance for waves. At the end of the previous reporting period, evaporation pond capacity had been modified by the addition of a 2 metre embankment raise to EP1. During the current reporting period the evaporation pond capacity was revised to reflect the recommissioning of EP2 storage capacity and the removal of EP3B storage capacity from service in September 2010. Reported liquor inventory in the evaporation ponds as a proportion of storage capacity was 109% of the normal maximum operational level (NMOL) at June 2011.

EP3B out of EP2 service recommissioning

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Note:  Normal operation and contingency limits revised to reflect the removal of EP3B storage capacity from service and the addition of recommissioned EP2 storage capacity. Figure 10-20: Evaporation pond capacity

10.3 Mine Water Disposal Pond (MWDP) 10.3.1 Background Water pumped from the Olympic Dam underground workings originates predominantly from the Arcoona Quartzite geological unit. The Arcoona Quartzite geological unit is fractured in its lower sections and yields water into the mine ventilation shafts, decline, haulage shafts and drill holes. The orebody and its host rocks generate little or no groundwater flows into the workings. Water collected from the mine is pumped to the surface storage (settling) ponds to allow for the slimes and fine particles to settle and “clean” water to be collected and re-used on site for dust suppression, soil conditioning during construction or underground mining

WASTE MONITORING PROGRAM Page 141 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT activities or is discharged to the MWDP for subsequent evaporation and recharging of the Andamooka Limestone aquifer (BHP Billiton Olympic Dam, 2009). Operational improvements have maximised the reuse of mine water and therefore minimised the disposal of saline water to the MWDP. As a result the MWDP is used on an intermittent occasional basis and therefore the risk of overtopping is minimal. 10.3.2 Purpose To monitor the operation and performance of the MWDP to identify potential for adverse environmental impact on soil and groundwater quality. 10.3.3 Deliverables(s) Maintain freeboard levels to within the maximum operational capacity. Fulfil requirements of the Groundwater Monitoring Program. 10.3.4 Method There are no current operational methods for monitoring Mine Water Disposal Pond levels. Quantities disposed of into the pond are captured in the Mine Water Balance. Water levels of the mine water settling ponds are monitored via Citect. Settled sludge is removed and disposed to the TSF. 10.3.5 Results/Discussion Water was discharged to the MWDP during FY11. Daily inspections were undertaken in accordance with the document (BHP Billiton Olympic Dam 2011b). Monitoring requirements of the Groundwater Monitoring Program (BHP Billiton Olympic Dam 2010c) were fulfilled and are discussed in Section 4.

10.4 Site and Olympic Village Sewage Ponds 10.4.1 Background Olympic Dam operates two onsite anaerobic sewage ponds and four anaerobic sewage ponds located at Olympic Dam Village. Their principal function is to contain and facilitate the anaerobic treatment of sewage from the metallurgical plant, mine and Olympic Dam Village. 10.4.2 Purpose Monitor the operation of the Sewage Ponds to minimise impact on soil and groundwater quality. 10.4.3 Deliverables(s) Monitor sewage ponds to identify potential for adverse environmental impact. Fulfil requirements of EPA Licence 3054. 10.4.4 Method Sewage Ponds are inspected on a daily basis to identify potential for adverse environmental impact. 10.4.5 Results/Discussion The sewage ponds at Olympic Dam Village (ODV) were monitored in accordance with the document (BHP Billiton Olympic Dam 2011b). Daily visual inspections were undertaken of the sewage ponds on site, and water quality monitoring was undertaken monthly. The requirements of EPA Licence 3054 were fulfilled.

Page 142 WASTE MONITORING PROGRAM 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT 10.5 Waste Management Centre 10.5.1 Background Most of the industrial and general waste materials generated at Olympic Dam are managed through the Waste Management Centre, which is located north-west of the Smelter and south of the quarry. An ongoing program has been established to minimise waste disposed to landfill through increased reuse and recycling. Recovered scrap material is cleaned and undergoes a formal radiation clearance procedure prior to leaving the site. The Waste Management Centre incorporates various categorised lay-down areas for the temporary storage of materials nominated for reuse or recycling. Material which cannot be reused or recycled is disposed of to the landfill facility, which is also located within the Waste Management Centre. At the landfill face, waste materials are deposited in thin layers and covered with clean fill material to facilitate containment of waste. Miscellaneous low level radioactive contaminated waste is disposed in the landfill. The Waste Management Centre is enclosed on all sides by either a two-metre high mesh fence topped with strands of barbed wire or a bund of height at least 1.5m. This is designed to restrict unauthorised access and function as a secondary litter containment control. 10.5.2 Purpose Monitor the disposal and recovery of industrial and general wastes to identify opportunities to minimise resource use intensity. 10.5.3 Deliverables(s)  Record quantities of general and industrial waste disposed of to landfill.  Record quantities of material recovered for reuse and recycling. 10.5.4 Method Waste materials generated across site are collected by the waste management contractor in a dedicated waste collection vehicle for recovery or disposal. At the time of collection, the operator of the vehicle records the quantity of the material and collection location where appropriate. In cases where material is delivered to the Waste Management Centre by operations personnel, the quantity, type and source of the material is recorded at the Waste Management Centre office prior to being placed in storage for subsequent recovery or disposal to landfill. The waste management contractor is responsible for processes associated with the reception, disposal, storage and recovery of waste materials and the control and operation of the Waste Management Centre facilities. Olympic Dam maintains systems to record quantities of industrial and general waste generated and subsequently disposed of or recovered for reuse or recycling. The waste management contractor is responsible for maintaining such records, which is entered into an electronic register. These include:  Cardboard collected.  General waste collected.  Waste disposed of in the TSF.  Materials sent off site for recycling.

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10.5.5 Results/Discussion From waste collection records, including waste delivered to the Waste Management Centre, it is estimated that approximately 35,922m3 (loose fill) was transported to the Waste Management Centre in FY11. This is a decrease of 3% on the volume of waste delivered to the Waste Management Centre in FY10. Bin records also show that approximately 787m3 of paper and cardboard waste was collected for recycling in FY11, a decrease of 10.5% of the volume collected in FY10.

10.6 Miscellaneous Hazardous Wastes 10.6.1 Background Miscellaneous hazardous wastes such as laboratory chemicals, process chemicals and process waste materials are generated on an ongoing basis at Olympic Dam and require appropriate disposal. Olympic Dam maintains systems and processes to control and administer the disposal of hazardous waste. Designated HSE personnel provide advice on the disposal of hazardous waste and authorise waste disposal within the Special Mining Lease (SML) primarily to the Tailings Storage Facility or Waste Management Centre. Low level radioactive waste is disposed in the TSF. Hazardous waste unsuitable for disposal within the SML is transported off site to an appropriate waste depot for further treatment, recycling or disposal. Off site disposal of hazardous waste categorised as listed waste (within the meaning of the Environment Protection Act 1993) is transported by an EPA licensed transporter to an EPA licensed waste depot and is undertaken in accordance with EPA guidelines for waste transport and tracking. 10.6.2 Purpose Manage miscellaneous hazardous wastes in an appropriate manner. 10.6.3 Deliverables(s)  Record categories, quantities, and location of hazardous waste materials disposed of within the SML.  Comply with the requirements pertaining to listed waste in EPA Licence 1301. 10.6.4 Method The disposal of hazardous waste is managed by the waste management contractor through the Waste Management Centre. Each material requiring disposal is assessed and the most appropriate disposal option is chosen. Olympic Dam maintains systems to record categories, quantities and location of hazardous waste materials disposed of within the SML. The waste management contractor is responsible for maintaining such records. The transport of hazardous waste off site is documented through the EPA waste transport and tracking system as required to provide assurance to regulators that wastes are managed appropriately. Hazardous waste disposal data (for wastes disposed of within the SML) are entered into an electronic register. Some low level radioactive waste (e.g. long lived low level radioactive sample waste) is disposed in the TSF. The location, type and quantity of low level radioactive waste disposed to the TSF are recorded.

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10.6.5 Results/Discussion Records of the hazardous materials disposed of within the SML were maintained by the waste management contractor during FY11. Data collected included the type of waste, quantity and disposal location. From these records it is estimated that approximately 7,917 tonnes of hazardous waste was disposed of within the SML in FY11. The requirements of EPA Licence 1301 pertaining to listed waste (67-578) were complied with in FY11.

10.7 Conclusions  Rainfall for the reporting period was 88% higher than the long term median annual rainfall. As a result of the high rainfall and significantly higher tailings deposition, the proportion of decant to evaporation ponds and liquor retained in tailings was significantly higher than the previous reporting period.  The combined area of the supernatant ponds on TSF Cells 1–3 varied between 7.6ha and 25.0ha over the reporting period with an average of 15.6ha, an increase of 84% from the previous years average of 8.5ha.  The supernatant pond area on TSF Cell 4 varied between 22.6ha and 42.5ha over the reporting period with an average of 30.5ha, an increase of 68% from the previous years average of 18.2ha.  A plan to bias tailings delivery to external walls of TSF Cell 4 achieved the target of 0.3m over the reporting period.  A number of dark areas with increased moisture were identified previously around the perimeter of the TSF and four additional areas have been identified in the current reporting period.  A filter blanket was constructed over Location 3 on the South Wall of TSF Cell 1 to minimise the risk of piping.  The results of the water balance indicate that the TSF has the capacity to dispose of excess liquor by evaporation although the unaccounted liquor may also include seepage from beach areas. Seepage from supernatant liquor ponds was estimated at 3% of liquor output.  Evaporation Pond 2 was recommissioned in November 2010, following problems with the wave barriers in the previous reporting period.  The sewage ponds at Olympic Dam Village were managed according to the document ‘Desalination Plant Reticulation Technician Task Guide’ and EPA licence 3054.  It is estimated that approximately 35,922m3 (loose fill) of general waste was transported to the Waste Management Centre in FY11.  Approximately 787m3 of paper and cardboard waste was collected for recycling in FY11.  It is estimated that approximately 7,917 tonnes of hazardous waste was disposed of within the SML in FY11.

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11 REFERENCES

ANZECC 2000, ‘Australian and New Zealand Guidelines for Fresh and Marine Water Quality’, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Paper No. 4, Volumes 1-3 (Chapters 1-9). Baillie, J and Goombridge B 1996, ‘1996 IUCN Red List of Threatened Animals’. IUCN, Gland, Switzerland. BHP Billiton Olympic Dam 2009, ‘Site Water Control Management Plan’, Olympic Dam Document No. 19245. BHP Billiton Olympic Dam 2010a, ‘Weed Management Strategy – Roxby Downs and Andamooka Region’, unpublished BHP Billiton Olympic Dam. BHP Billiton Olympic Dam 2010b, ‘Environmental Management Program FY11 – FY13’, Olympic Dam Document No. 49329. BHP Billiton Olympic Dam 2010c, ‘Monitoring Program – Groundwater FY11’, Olympic Dam Document No. 2791. BHP Billiton Olympic Dam 2010d, ‘Monitoring Program – Great Artesian Basin (GAB) FY11, Olympic Dam Document No. 2789. BHP Billiton Olympic Dam 2010e, ‘Environmental management and monitoring report, 1 July 2009 to 30 June 2010’, unpublished report for BHP Billiton Olympic Dam, report no..ODENV041. BHP Billiton Olympic Dam 2010f, ‘Tailings Retention System Technician Daily Routine’, Olympic Dam Document No. 4280. BHP Billiton Olympic Dam 2010g, ‘Tailings Management Plan’, Olympic Dam Quality Document No. 80791. BHP Billiton Olympic Dam 2011a, ‘BHP Billiton Olympic Dam - Great Artesian Basin Wellfields Report 1 July 2010 to 30 June 2011’, unpublished BHP Billiton Olympic Dam Report No. ODENV049. BHP Billiton Olympic Dam 2011b, ‘Desalination Plant Reticulation Technician Task Guide’, Olympic Dam Document No. 77985. Crouch, P, Green, S and Worby, M 2003, ‘Radiation doses to members of the public from the Olympic Dam Operation’, Presented at the Annual Conference of the Australian Radiation Protection Society, October 2003, Hobart. DEH, 2006, ‘Threatened species and ecological communities’, Department of Environment and Heritage, South Australia. Environment Protection (Air Quality) Policy, 1994. Fatchen Environmental. 2005. An assessment of WMC (Olympic Dam Corporation) emissions impact on the flora of the special mining lease and surrounds [2004]. Report for WMC (Olympic Dam Corporation) Pty Ltd. Mt Barker, SA: Fatchen Environmental Pty Ltd. Griffin, G.F. and Dunlop, S.R. 2006, ‘Impact of Emissions from the Olympic Dam Mine Operation on the Flora and Soil of the Special Mining Lease.’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW.

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Griffin, G.F. and Dunlop, S.R. 2007, ‘Impact of Emissions from the Olympic Dam Mine Operation on the Flora and Soil of the Special Mining Lease.’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW. Griffin, G.F. and Dunlop, S.R. 2007a, ‘Emissions dispersal patterns and impacts on soils and vegetation in the Olympic Dam operation area.’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW. Griffin, G.F. and Dunlop, S.R. 2009, ‘Impact of Emissions from the Olympic Dam Mine Operation on the Flora and Soil of the Special Mining Lease.’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW. Griffin, G.F. and Dunlop, S.R. 2010a, ‘Impact of Emissions from the Olympic Dam Mine Operation on the Flora and Soil of the Special Mining Lease.’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW. Griffin, G.F. and Dunlop, S.R. 2010b, ‘Long-term changes in the composition of perennial vegetation in response to emissions from the Olympic Dam operation’, unpublished report to BHP Billiton, Datasticians, Pillar Valley, NSW. Kershaw, KA and Looney, JHH 1985, ‘Quantitative and Dynamic Plant Ecology (3rd Ed)’, Edward Arnold, London. Kinhill Engineers 1997, ‘Olympic Dam Expansion Project: Environmental Impact Statement’, Kinhill Engineers Pty Ltd, Adelaide. National Greenhouse and Energy Reporting Act 2007. National Greenhouse Gas and Energy Reporting Regulations 2008. National Parks and Wildlife (SA) Act 1972. Natural Resources Management Act 2004. Niejalke, DP and Lamb, K 2002, ‘Can remote sensing monitor GAB spring impacts? A progress update’, conference paper presented to the Mound Spring Researchers Forum, Toowoomba, March 2002. Ponder, WF 1986, ‘Mound spring snails of the Great Artesian Basin’, in Limnology in Australia, Eds DeDecker P and Williams WD, CSIRO Australia, Melbourne. Ponder, WF, Hershler, R, and Jenkins, B 1989, ‘An endemic radiation of Hydrobiid Snails from artesian springs in northern South Australia: their taxonomy, physiology, distribution and anatomy’, Malacologia 31(1): 1-140. Read, JL 1998, ‘Are geckos useful bioindicators of air pollution?’, Oecologia 114: 180- 187. Read, JL, Kovac, K and Fatchen, TJ 2005, ‘Biohyets: a holistic method of demonstrating the extent and severity of environmental impacts’, Journal of Environmental Management 77: 157-164. Read, JL, Reid, N and Venables, WN 2000, ‘Which bird species are useful indicators of mining and grazing impacts in arid South Australia?’, Environmental Management 26(2): 215-232. Read, JL and Tyler MJ 1990, ‘The nature and incidence of post-axial, skeletal abnormalities in the frog Neobatrachus centralis Parker at Olympic Dam, South Australia’, Transactions of the Royal Society of South Australia 114(4): 213-217. Roxby Downs (Indenture Ratification) Act 1982.

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Tyre, AJ and Possingham, HP 2001, ‘Risk management for ecologically sustainable development: predicting extinction and recolonisation in the mound springs of SA – Final Report’, unpublished report for Olympic Dam and the University of Queensland. United Nations. 1998. Kyoto Protocol to the United Nation Framework Convention on Climate Change. Kyoto, United Nations. Williams, AF and Holmes, JW 1978, ‘A novel method of estimating the discharge of water from mound springs of the Great Artesian Basin, Australia’, Journal of Hydrology 38: 263-272.

Page 148 REFERENCES 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

12 GLOSSARY OF TERMS

ADU Ammonium diuranate, commonly referred to as Yellowcake. AHD Australian Height Datum, a measure of elevation referenced from approximate sea level. Aquifer Porous water bearing formation of permeable rock, sand, or gravel capable of yielding significant quantities of water. Bq Bequerel, a unit of radioactive decay. CEM Continuous emissions monitoring. Ca Calcium. CAF Cemented aggregate fill. Closure Permanent cessation of operations at a mine or mineral processing site after completion of the decommissioning process, signified by tenement relinquishment. Cu Copper. DCF Dose conversion factor. Decommissioning Activities carried out prior to closure of the site (as operating costs) which include flushing of lines, depressurisation of systems and vessels and removal of hazardous materials (excluding oils and greases) and radioactive sources unless noted otherwise in the site closure plan. Domestic Water Water used in the town of Roxby Downs or Olympic Dam Village. Use EC Electrical conductivity. EDE Effective dose equivalents. EIHCP Environmental / Indigenous Heritage Clearance Permit. EPMP Environmental Protection and Management Program. Describes the environmental management and monitoring activities undertaken by BHP Billiton Olympic Dam for the purpose of quantifying any change in the extent or significance of its impacts, assessing the performance of control measures employed to limit impacts, and/or to meet legal and other obligations. EMS Environmental Management System. The part of an organisation’s management system used to develop and implement its environmental policy and manage its environmental aspects (Standards Australia / Standards New Zealand 2004). Note: A management system is a set of interrelated elements used to establish policy and objectives and to achieve those objectives. A management system includes organisational structure, planning activities, responsibilities, practices, procedures, processes and resources. Environmental An element of the organisation’s activities or products or services Aspect that can interact with the environment (Standards Australia / Standards New Zealand 2004).

GLOSSARY OF TERMS Page 149 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Environmental Any change to the environment, whether adverse or beneficial Impact wholly or partially resulting from an organisation’s environmental aspects (Standards Australia / Standards New Zealand 2004). EPA Environment Protection Authority. Evaporation Pond A containment pond to hold liquid wastes to assist with disposal of liquor via evaporation. Fe Iron. GAB Great Artesian Basin. HDPE High density polyethylene. HVAS High Volume Air Sampler(s) ICRP International Commission on Radiological Protection. Industrial Water Water used in mining or mineral processing operations and use excluding domestic water use. Mn Manganese. MP Monitoring Program. A document which describes the environmental monitoring activities undertaken by BHP Billiton Olympic Dam for the purpose of quantifying any change in the extent or significance of its impacts, assessing the performance of the control measures employed to limit its impacts, and/or to meet its legal and other obligations. NaCI Sodium chloride (salt).

Na2S Sodium sulfide. NEPM National Environment Protection Measure. Nm3 Normal metres cubed, referring to volume at a standard temperature and pressure.

NOx Oxides of nitrogen. OD Olympic Dam. ODV Olympic Dam Village monitoring site. PAH Poly aromatic hydrocarbons. Pb Lead. 210Pb An isotope of lead, having mass number 82 and half-life 22.3 years. pH A measure of acidity and alkalinity.

PM10 Particulate matter with an diameter less than or equal to 10 µm Po Polonium. 210Po An isotope of polonium, having mass number 84 and half-life 138.38 days. Ra Radium. 226Ra An isotope of radium, having mass number 88 and half-life 1599 years.

Page 150 GLOSSARY OF TERMS 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

Radon Chemically inert radioactive gaseous element formed from the decay of uranium. RDS Roxby Downs Township monitoring site. Rehabilitation The reclamation or repair, as far as practicable, of a facility to an appropriate or agreed state as required by law, or company self- regulation. Rn Radon. 222Rn An isotope of radon, having mass number of 86 and half-life 3.8235 days. Significant aspect An environmental aspect that has or can have a significant environmental impact. Significance is determined by risk assessment. SML Special Mining Lease.

SOx Oxides of sulphur.

SO2 Sulphur dioxide.

SO3 Sulphur trioxide.

SO4 Sulphate. SWL Standing water level. TDS Total dissolved solids. Th Thorium. 230Th An isotope of thorium, having mass number 90 and half-life 7.54 × 104 years. Total Industrial Total water used including high quality (GAB) water and water Water Use recovered from other sources including abstraction of local saline water. TRS Tailings Retention System. Incorporates all elements of the tailings delivery, deposition and storage system and elements associated with the collection and disposal or return of tailings liquor. The TRS includes the Tailings Storage Facility (TSF), Evaporation Ponds and Pipe Corridors including tailings delivery pipelines and liquor pipelines. TSF Tailings Storage Facility. Incorporates the tailings deposition and storage system, which currently comprises four storage cells. TSP Total Suspended Particulates (dust) U Uranium. 238U The most common isotope of uranium, having mass number 238 and half-life 4.46 × 109 years. UOC Uranium oxide concentrate, final uranium product at BHP Billiton Olympic Dam, consisting of 99% U3O8. VOC Volatile organic compound.

GLOSSARY OF TERMS Page 151 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

13 APPENDIX 1: SUMMARY OF EXTERNALLY REPORTABLE SPILLS

Date Event Cause Impact reported 01/09/10 Approx 86m3 of acidic Butt weld failure on a There was no occupational liquor was released into Evaporation Pond Return health and safety or the tailings pipeline Liquor (EPRL) Line. environmental impacts. corridor along the east The spilt material was side of TSF Cell 2/3. recovered and disposed of in the Tailings Storage Facility. 13/02/11 Approx 5-10g of Small clumps of ADU There was no occupational concentrated uranium; dislodged and deposited health and safety or ammonia diuranate outside of the bund during environmental impacts. (ADU) outside of bund maintenance activities The spilt material was in the Precipitation area. which involved replacing recovered and disposed of structural unsound steel in the Tailings Storage and cladding. Facility. 15/02/11 Approx 120 m3 of acidic Butt weld failure on a There was no occupational liquor was released into Evaporation Pond Return health and safety or the tailings pipeline Liquor (EPRL) Line. environmental impacts. corridor west of Solvent The spilt material was Extraction. recovered and disposed of in the Tailings Storage Facility. 01/05/11 Approx 180m3 of Sleeve failure on valve There was no occupational radioactive process UV1309 line 2 resulted in health and safety or material was released acidic tailings slurry being environmental impacts. outside bund area at released outside of bund The spilt material was Tailings Disposal. area. recovered and disposed of in the Tailings Storage Facility.

Page 152 APPENDIX 1: SUMMARY OF EXTERNALLY REPORTABLE SPILLS 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

14 APPENDIX 2: METEOROLOGICAL DATA

As shown in Figure 14-1, a total of 278.4mm of rainfall was measured for the reporting period. This is well above the long-term (1931 – present) median annual rainfall of 136.3mm.

120

100

80

60 Rainfall (mm)

40

20

0 Jul-2010 Oct-2010 Jun-2011 Jan-2011 Apr-2011 Mar-2011 Nov-2010 Feb-2011 Aug-2010 Sep-2010 Dec-2010 May-2011

Rainfall Long Term Monthly Median

Figure 14-1: Annual rainfall FY11 Figure 14-3 illustrates the annual wind rose for the reporting period. Wind speed and direction data recorded from the BOM weather station has been used to indicate the wind vector. Due to the use of new Grapher software to compile the wind rose for FY10, incorrect settings were used and as a result the wind rose produced was not accurate. This has since been corrected and a new wind rose produced for FY10. Figure 14-3 illustrates the annual wind rose for FY10. Wind speed and direction data recorded from the BOM weather station has been used to indicate the wind vector.

APPENDIX 2: METEOROLOGICAL DATA Page 153 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

North 0

315 45

270 90

0% 4% 8% 12% 16% 20%

225 135

180 Wind Speed (knots) <=5 >5 - 10 >10 - 15 >15

 Note: wind direction indicated is from the outside of the circle toward the centre. Figure 14-2: Wind rose, FY11

Page 154 APPENDIX 2: METEOROLOGICAL DATA 1 JULY 2010 - 30 JUNE 2011 BHP BILLITON OLYMPIC DAM ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

North 0

315 45

270 90

0% 4% 8% 12% 16% 20%

225 135

180 Wind Speed (knots) <=5 >5 - 10 >10 - 15 >15

 Note: wind direction indicated is from the outside of the circle toward the centre. Figure 14-3: Corrected Wind rose, FY10

APPENDIX 2: METEOROLOGICAL DATA Page 155 BHP BILLITON OLYMPIC DAM 1 JULY 2010 - 30 JUNE 2011 ENVIRONMENTAL MANAGEMENT AND MONITORING REPORT

15 APPENDIX 4: CONSULTANTS UTILISED BETWEEN 1 July 2010 – 30 June 2011

Air Emissions Sampling  Axiom Air (Adelaide, SA)

Aerial Photography  Fugro Spatial Solutions (Eight Mile Plains, QLD)

EMS  SGS Australia Pty Ltd, Systems and Services Certification (Adelaide, SA)

Energy and Greenhouse Gas Reporting  GHD Consulting (Sydney, NSW)  Balance Energy (Adelaide, SA)

Flora  Datasticians (Pillar Valley, NSW)

GAB  Land Use Consultants (Clare, SA)  Australia Water Environments

Tailings Management  Knight Piesold (Sydney, NSW)  Coffey Geosciences Pty Ltd  GHD Consulting (Sydney, NSW)  Sinclair Knight Merz (SKM) (Melbourne, VIC)  Exact Mining Services (Wayville, SA)

Page 156 APPENDIX 4: CONSULTANTS UTILISED BETWEEN 1 July 2010 – 30 June 2011