RUM JUNGLE REHABILITATION PROJECT MONITORING REPORT 1993 … · rum jungle rehabilitation project monitoring report 1993-1998 edited by s m pidsley technical report number 01/2002

RUM JUNGLEREHABILITATION PROJECT

MONITORING REPORT1993-1998

JULY 2002

First Published 2002

� Department of Infrastructure, Planning and Environment

ISBN 0724548211

COVER PHOTOGRAPH

Rum Jungle aerial photo 1999.

RUM JUNGLEREHABILITATION PROJECT

MONITORING REPORT1993-1998

EDITED BY S M PIDSLEY

TECHNICAL REPORT NUMBER 01/2002

DEPARTMENT OF INFRASTRUCTURE, PLANNING AND ENVIRONMENTJULY 2002

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TABLE OF CONTENTS1. SUMMARY ________________________________________________________________ 1

1.1. INTRODUCTION 11.2. MANAGEMENT AND MONITORING 11.3. SURFACE WATER MONITORING 21.4. WATER QUALITY IN WHITES AND INTERMEDIATE OPEN CUT WATER BODIES 41.5. VEGETATION DIEBACK ON DYSONS OPEN CUT, IMPLICATIONS, CAUSAL

MECHANISMS AND OPTIONS FOR REMEDIATION 51.6. EFFECTIVENESS OF COVERS ON THE OVERBURDEN HEAPS 61.7. MEASURES OF ECOLOGICAL IMPACT IN THE FINNISS RIVER DOWNSTREAM OF THE

RUM JUNGLE REHABILITATED SITE, 1993-98 61.8. SITE INTEGRITY 7

2. MANAGEMENT AND MONITORING: A DISCUSSION OF ISSUES AFFECTINGFUTURE LAND USE, MANAGEMENT AND MONITORING _______________________ 92.1. INTRODUCTION 92.2. ENVIRONMENTAL IMPACTS 102.3. REHABILITATION AND MONITORING 1982-1998 12

Rehabilitation objectives 12Rehabilitation standards 14Monitoring arrangements 151986-1988 monitoring recommendations 161988-1993 monitoring recommendations 171993-1998 monitoring 18

2.4. CONTEXTUAL ISSUES FOR FUTURE MANAGEMENT AND MONITORING 21Contemporary standards 21Final land use 22Land use options 25

2.5. CONCLUSION AND SUGGESTIONS FOR FURTHER WORK 26

3. SURFACE WATER MONITORING ____________________________________________ 293.1. INTRODUCTION 29

Gauge station network – data collection 303.2. METHODS 32

Hydrological data 32Chemical analysis 34

3.3. RESULTS AND DISCUSSION 34Hydrology of early and late flows at gauge stations GS 8150200 and GS 8150097 34Comparison of hydrological data at GS 8150200 and GS 8150212 36Open cut gauge stations GS 8150213 and GS 8150212 38Annual Contaminant Loads 40pH – a measure of the acid in acid mine drainage 43Frequency distribution of metal concentrations recorded at GS 8150097 46Contaminant loads – delivery schedules to the receiving environment 53Finniss River downstream of the confluence with its East Branch (GS 8150204) 55Dysons open cut landform – run-off monitoring 58East Finniss River reach surveys 60

3.4 WATER SAMPLING – ERROR ESTIMATIONS ON COMPOSITE SAMPLES 68Methodology 69Results and discussion 69

3.5 SUGGESTIONS FOR FURTHER WORK BASED ON THE 1993/1998 SURFACE WATERMONITORING PROGRAM. 71

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4. WATER QUALITY IN WHITES AND INTERMEDIATE OPEN CUTS _______________ 744.1. OVERVIEW 744.2. PROFILING OF WHITES OPEN CUT 75

Temperature 76pH 76Copper 78Manganese 78Zinc 78Conductivity 79

4.3. WHITES COPPER INVENTORY AND THE DEPTH OF THE PYCNOCLINE 814.4. WHITES AND INTERMEDIATE OPEN CUT WATER QUALITY 844.5. RADIOLOGICAL ANALYSIS OF WHITES AND INTERMEDIATE OPEN CUTS 854.6. PHYSICAL-CHEMICAL ANALYSIS OF WHITES AND INTERMEDIATE OPEN CUTS 874.7 SUGGESTIONS FOR FURTHER WORK 92

5. VEGETATION DIEBACK ON DYSONS OPEN CUT; IMPLICATIONS, CAUSALMECHANISMS AND OPTIONS FOR REMEDIATION ____________________________ 945.1. INTRODUCTION 945.2. BACKGROUND 955.3. OBJECTIVES 975.4. METHODS 985.5. RESULTS AND DISCUSSION 1025.6. REMEDIATION OPTIONS 110

6. EFFECTIVENESS OF COVERS ON THE OVERBURDEN HEAPS _________________ 1136.1. INTRODUCTION 1136.2. INSTRUMENTATION OF OVERBURDEN HEAPS 114

Whites and Intermediate heaps 114Dysons heap 116

6.3. METHODS 118Infiltration rates 118Temperature measurements 119Oxygen concentration measurements 119Calculation of oxidation rates 120Oxygen diffusion coefficient of the cover 122

6.4. RESULTS 123Infiltration rates 123Temperature measurements 124Oxygen concentration measurements 124Oxidation rates 126Intermediate heap 128Effect of oxygen diffusion coefficient on calculated oxidation rates 131Oxygen diffusion coefficient of the cover 132

6.5. DISCUSSION 133Infiltration rates 133Temperature measurements 134Pore gas oxygen concentration measurements 134Oxidation rates 137Oxygen diffusion coefficient of the cover 139

6.6. CONCLUSIONS 1396.7. SUGGESTIONS FOR FURTHER WORK 140

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7. MEASURES OF ECOLOGICAL IMPACT IN THE FINNISS RIVER DOWNSTREAM OFTHE RUM JUNGLE REHABILITATED SITE 1993-98____________________________ 1427.1. INTRODUCTION 1427.2. MACROINVERTEBRATE SURVEYS - FINNISS RIVER 143

Introduction 143Methods 144Results and discussion 145

7.3. DECAPOD SURVEYS - EAST BRANCH 148Introduction 148Results and discussion 148

7.4. BENTHIC MACROINVERTEBRATE SURVEYS – TEMPORAL AND SPATIALDISTRIBUTION IN THE EAST BRANCH 149Introduction 149Site selection 150Sampling frequency 151Methodology and materials 152Results and discussion 153Conclusion 160

7.5. ARCHIVAL MONITORING STUDY 161Introduction 161Methodology 162Results and discussion 162

7.6. FIRST FLUSH ASSESSMENT 169Background 169Introduction 170Aims and constraints on the study 170Methods 170Results and discussion 171ANZECC 1992 guideline values 174

7.7. SYNOPSIS 177Other considerations 178

7.8. SUGGESTIONS FOR FURTHER WORK 179Mussel translocation experiments and sediment ecotoxicology 181Benthic algae and bacteria 181Shrimp translocation experiments, seasonal variation 182

8. SITE INTEGRITY _________________________________________________________ 1838.1. INTRODUCTION 1838.2. WEED MANAGEMENT 183

Mimosa 184Grader grass 185Other weeds 187Access tracks 187Future management 187

8.3. EROSION CONTROL 188Whites overburden heap 189Dysons open cut landform and overburden heap 190Tailings dam 190Access tracks 190Other 191

8.4. SITE ACCESS 1918.5. WILDFIRES 1928.6. FERAL ANIMALS 1938.7. LONGER TERM SITE INTEGRITY ISSUES 1938.8. RADIOLOGICAL STATUS 1948.9. RECOMMENDATIONS 195

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9. REFERENCES ____________________________________________________________ 197

APPENDIX A __________________________________________________________________ 202

APPENDIX B __________________________________________________________________ 224

LIST OF FIGURESFIGURE 2.1 LOCATION OF THE RUM JUNGLE REHABILITATION SITE................................................................... 11FIGURE 2.2 RUM JUNGLE SITE PLAN.................................................................................................................. 12

FIGURE 3.1 EARLY WET SEASON HYDROLOGY AT GS8150200 AND GS8150097 (1997-98).............................. 35FIGURE 3.2 THE DIVERSION CHANNEL AND WEIRS BUILT ON THE EAST FINNISS RIVER TO CONTROL RIVER

FLOW...................................................................................................................................... 36FIGURE 3.3 COMPARATIVE HYDROLOGY GS 8150200 AND GS 8150212 (1993/94) ......................................... 37FIGURE 3.4 COMPARATIVE HYDROLOGY GS 8150200 AND GS 8150212 (1997/98) ......................................... 37FIGURE 3.5 COMPARATIVE HYDROLOGY GS 8150212 AND GS 8150213 (1997/98) ......................................... 38FIGURE 3.6 COPPER LOADS (IN KG) AS ESTIMATED AT GS 8150213, 8150212, 8150200 AND 8150097 FROM

1993/1994 TO 1997/1998 ....................................................................................................... 40FIGURE 3.7 ANNUAL COPPER LOADS (T) VERSUS ANNUAL DISCHARGED VOLUME (106M3)................................. 42FIGURE 3.8 ANNUAL COPPER LOAD (T) ESTIMATED AT GS 8150097 FROM 1990-1991 TO 1997-1998. ............. 43FIGURE 3.9 FREQUENCY HISTOGRAM OF THE PREVAILING PH AT GS 8150097 DURING THE PRE-

REHABILITATION PERIOD (1967-1981) ................................................................................... 44FIGURE 3.10 FREQUENCY HISTOGRAM OF THE PREVAILING PH AT GS 8150097 DURING THE POST-

REHABILITATION PERIOD (1990-1995) ................................................................................... 45FIGURE 3.11 MEAN PH VALUES OF WATER SAMPLES COLLECTED AT GS 8150097 DURING PRE-

REHABILITATION (1968-1985) AND POST-REHABILITATION (1990-1995) PERIODSCLASSIFIED BY MONTH OF SAMPLING...................................................................................... 46

FIGURE 3.12 FREQUENCY AND CUMULATIVE PERCENT FREQUENCY HISTOGRAM OF COPPER CONCENTRATIONVALUES (MG/L) AT GS 8150097 DURING THE PRE-REHABILITATION PERIOD (1968-1981)..... 47

FIGURE 3.13 FREQUENCY AND CUMULATIVE PERCENT FREQUENCY HISTOGRAM OF COPPER CONCENTRATIONVALUES (MG/L) AT GS 8150097 DURING THE PERIOD 1990-1995.......................................... 47

FIGURE 3.14 MEAN MONTHLY COPPER CONCENTRATIONS (TOTAL IN MG/L) OF WATER SAMPLES COLLECTEDAT GS 8150097 DURING TWO SEPARATE PERIODS: 1968-1985 AND 1990-1995..................... 48

FIGURE 3.15 MEAN MONTHLY COPPER CONCENTRATIONS (TOTAL IN MG/L) OF WATER SAMPLES COLLECTEDDAILY AT GS 8150097 FROM DECEMBER 1990 TO JUNE 1995. .............................................. 49

FIGURE 3.16 FREQUENCY AND CUMULATIVE FREQUENCY HISTOGRAM OF ZINC CONCENTRATION (MG/L) ASMEASURED AT GS 8150097 DURING THE PRE-REHABILITATION PERIOD (1968-1981) ............ 50

FIGURE 3.17 FREQUENCY AND CUMULATIVE PERCENT FREQUENCY HISTOGRAM OF ZINC CONCENTRATION(MG/L) AS MEASURED AT GS 8150097 DURING THE POST-REHABILITATION PERIOD (1990-1995)...................................................................................................................................... 51

FIGURE 3.18 FREQUENCY AND CUMULATIVE PERCENT FREQUENCY HISTOGRAM OF MANGANESECONCENTRATION (MG/L) AS MEASURED AT GS 8150097 DURING THE PRE-REHABILITATION PERIOD (1968-1981) ................................................................................... 52

FIGURE 3.19 FREQUENCY AND CUMULATIVE PERCENT FREQUENCY HISTOGRAM OF MANGANESECONCENTRATION (MG/L) AS MEASURED AT GS 8150097 DURING THE POST-REHABILITATION PERIOD (1990-1995) ................................................................................... 52

FIGURE 3.20 CUMULATIVE FLOW AND CUMULATIVE COPPER LOAD AT GS 8150200 AND 8150212 OVER WETSEASON 1997/1998................................................................................................................. 53

FIGURE 3.21 CUMULATIVE AND SPOT COPPER LOADS AT GS 8150200 AND GS 8150212 OVER WET SEASON1997-1998.............................................................................................................................. 55

FIGURE 3.22 AVERAGE MONTHLY COPPER CONCENTRATIONS (MG/L) AT GS 8150097 AND GS 81500204DURING THE 1994/1995 WET SEASON (ERROR BARS INDICATE STANDARD DEVIATIONS) ........ 56

FIGURE 3.23 MAP OF THE SAMPLING SITES ALONG THE EAST FINNISS RIVER AND THE LOCATION OFGAUGING STATIONS GS 8150097 AND GS 8150200............................................................... 62

FIGURE 3.24 HYDROLOGY OF LATE WET SEASON FLOW AT GS 8150097 AND GS 8150200 IN 1994................... 63FIGURE 3.25 WATER QUALITY MEASURES (INCLUDING HEAVY METALS) ALONG THE REACH OF THE EAST

FINNISS RIVER AS RECORDED ON SAMPLES COLLECTED 22/04/94 .......................................... 64FIGURE 3.26 WATER QUALITY MEASURES (INCLUDING SULFATE, CALCIUM & MAGNESIUM) ALONG THE

REACH OF THE EAST FINNISS RIVER AS RECORDED ON SAMPLES COLLECTED 22/04/94.......... 65FIGURE 3.27 LATE WET SEASON (1995) HYDROLOGY AT GAUGE STATIONS GS 8150097 AND GS 8150200....... 67FIGURE 3.28 VARIATION IN WATER QUALITY MEASURES IN THE EAST BRANCH OF THE FINNISS RIVER WITH

DISTANCE DOWNSTREAM FROM RUM JUNGLE ON 15/06/95 .................................................... 68FIGURE 3.29 NORMALISED METAL CONCENTRATIONS FROM 15 INDIVIDUAL SUB-SAMPLES COLLECTED ON

THE 23/03/99.......................................................................................................................... 71

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FIGURE 4.1 ISOPLETH DIAGRAM OF WHITES OPEN CUT TEMPERATURE CHANGES WITH DEPTH (TO 32 MAHD) FROM JANUARY 1993 TO DECEMBER 1995.................................................................. 77

FIGURE 4.2 ISOPLETH DIAGRAM OF WHITES OPEN CUT PH CHANGES WITH DEPTH (TO 30 M AHD) ANDTIME FROM JANUARY 1993 TO DECEMBER 1995 .................................................................... 77

FIGURE 4.3 ISOPLETH DIAGRAM OF WHITES OPEN CUT COPPER CONCENTRATIONS (MG/L) WITH DEPTH (TO36M AHD) AND TIME FROM JANUARY 1993 TO DECEMBER 1995 .......................................... 78

FIGURE 4.4 ISOPLETH DIAGRAM OF WHITES OPEN CUT MANGANESE CONCENTRATIONS (MG/L) WITH DEPTH(TO 36M AHD) AND TIME FROM JANUARY 1993 TO DECEMBER 1995.................................... 80

FIGURE 4.5 ISOPLETH DIAGRAM OF WHITES OPEN CUT ZINC CONCENTRATIONS (MG/L) WITH DEPTH (TO 36M AHD) AND TIME FROM JANUARY 1993 TO DECEMBER 1995 .............................................. 80

FIGURE 4.6 ISOPLETH DIAGRAM OF WHITES OPEN CUT CONDUCTIVITY (µS/CM) WITH DEPTH (TO 32 MAHD) AND TIME FROM JANUARY 1993 TO DECEMBER 1995.................................................. 81

FIGURE 4.7 DEPTH (AHD) OF PYCNOCLINE IN WHITES OPEN CUT VS. TIME 27/08/1986 TO 29/04/1998 .......... 83FIGURE 4.8 COPPER INVENTORY (IN T) IN WHITES OPEN CUT ABOVE AND BELOW THE PYCNOCLINE FROM

1986-1998.............................................................................................................................. 83FIGURE 4.9 COPPER INVENTORY IN WHITES OPEN CUT ABOVE THE PYCNOCLINE (1990-1998)......................... 84

FIGURE 5.1 SITE LAYOUT OF THE RUM JUNGLE REHABILITATED SITE ................................................................ 95FIGURE 5.2 APPROXIMATE LOCATION OF CORING POSITIONS ON DYSONS OPEN CUT ........................................ 99FIGURE 5.3 DIAGRAMMATIC REPRESENTATION OF THE PH DISTRIBUTION WITHIN THE SOIL CAPPING AT

TRANSECT 2. ........................................................................................................................ 106FIGURE 5.4 DIAGRAMMATIC REPRESENTATION OF THE DTPA-EXTRACTABLE CU DISTRIBUTION WITHIN THE

SOIL CAPPING AT TRANSECT 2. ............................................................................................. 106FIGURE 6.1 LYSIMETER POSITIONS ON WHITES AND INTERMEDIATE OVERBURDEN HEAPS. TWO LYSIMETERS

ARE LOCATED AT EACH POSITION MARKED BY A TRIANGLE.................................................. 114FIGURE 6.2 LOCATION OF PROBE HOLES USED TO MONITOR TEMPERATURE AND PORE GAS CONCENTRATION

PROFILES IN INTERMEDIATE AND WHITES HEAPS................................................................. 115FIGURE 6.3 LAYOUT OF POST-REHABILITATION PROBE HOLES INSTALLED AT RUM JUNGLE ............................ 116FIGURE 6.4 LOCATION OF PROBE HOLES ON DYSONS HEAP.............................................................................. 118FIGURE 6.5 OVERALL OXIDATION RATE IN WHITES HEAP AS A FUNCTION OF TIME.......................................... 128FIGURE 6.6 OVERALL OXIDATION RATE IN INTERMEDIATE HEAP AS A FUNCTION OF TIME............................... 131

FIGURE 7.1 POPULATIONS OF ATYIDS AT SITES IN THE FINNISS RIVER OVER THREE SAMPLING PERIODS. ........ 147FIGURE 7.2 LOCATION OF STUDY AREA AND MAIN SAMPLING SITES ................................................................ 151FIGURE 7.3 ELECTRICAL CONDUCTIVITY (EC) AT FOUR SITES IN THE EAST BRANCH...................................... 154FIGURE 7.4 COPPER CONCENTRATIONS AT FOUR SITES IN THE EAST BRANCH ................................................. 155FIGURE 7.5 ZINC CONCENTRATIONS AT FOUR SITES IN THE EAST BRANCH ...................................................... 155FIGURE 7.6 TOTAL NUMBER OF TAXA (FAMILIES) AT SELECTED SITES IN THE EAST BRANCH CATCHMENT

DURING THE RECESSIONAL FLOW PERIOD ............................................................................. 156FIGURE 7.7 AVERAGE ABUNDANCE (NUMBER OF ANIMALS) AT SITES IN THE EAST BRANCH CATCHMENT

DURING THE RECESSIONAL FLOW PERIOD ............................................................................. 157FIGURE 7.8 DENDROGRAM REPRESENTING BRAY-CURTIS SIMILARITIES OF ALL AVERAGED SITES FROM

RUNS 5, 6, 8 AND 10. ............................................................................................................ 158FIGURE 7.9 MULTI DIMENSIONAL SCALING ORDINATION OF BRAY-CURTIS SIMILARITIES FROM ALL

AVERAGED SITES FROM RUNS 5, 6, 8 AND 10........................................................................ 159FIGURE 7.10 BACKGROUND CU/CA SIGNAL FROM A SHELL COLLECTED IN THE EAST BRANCH UPSTREAM OF

THE FORMER MINE SITE......................................................................................................... 163FIGURE 7.11 DECLINING CU/CA SIGNAL IN A MUSSEL SHELL COLLECTED IN THE FINNISS RIVER ≈ 14 KM

DOWNSTREAM OF THE EAST BRANCH CONFLUENCE............................................................. 163FIGURE 7.12 AVERAGE COPPER CONCENTRATIONS IN SOFT TISSUES OF MUSSELS COLLECTED 1981 AND 1995 167FIGURE 7.13 CALCIUM CONCENTRATIONS IN SOFT TISSUES OF MUSSELS FROM SITES WITHIN THE FINNISS

RIVER CATCHMENT .............................................................................................................. 169FIGURE 7.14 CONCENTRATION OF COPPER IN FILTERED WATER FROM THE EAST BRANCH AND THE FINNISS

RIVER OVER THE PERIOD THAT WATER BEGAN TO FLOW DOWN THE EAST BRANCH IN1997. .................................................................................................................................... 173

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LIST OF TABLES

TABLE 2.1 OBJECTIVES, RESULTS ACHIEVED, PRIMARY TREATMENTS AND STANDARDS ADOPTED FOR THERUM JUNGLE REHABILITATION PROJECT................................................................................ 13

TABLE 2.2 TOTAL EXPENDITURE ON MONITORING AND MAINTENANCE AT THE RUM JUNGLE SITE SINCECOMPLETION OF REHABILITATION. ......................................................................................... 16

TABLE 2.3 ORIGINAL COST SHARING ARRANGEMENTS OVER THE FIVE-YEAR MONITORING PERIOD.................. 20

TABLE 3.1 HISTORICAL LOAD DATA (IN T) OF SELECTED POLLUTANTS SOURCED FROM THE RUM JUNGLEREHABILITATED SITE AS MEASURED AT GAUGING STATION GS 81500971. ............................ 41

TABLE 3.2 STATISTICAL DATA OF PH MEASURED AT GS 8150097 DURING PRE- ANDPOST-REHABILITATION PERIODS CLASSIFIED ACCORDING TO THE MONTH OF SAMPLING......... 45

TABLE 3.3 STATISTICAL ANALYSES OF COPPER CONCENTRATIONS OF WATER SAMPLES FROM GS 8150097BASED ON THE MONTH OF COLLECTION AND COMPARING PRE- AND POST-REHABILITATIONDATA ...................................................................................................................................... 48

TABLE 3.4 COMPARISON OF POLLUTANT LOADS (T) ESTIMATED AT GS 8150097 AND GS 8150204 IN WETSEASONS 1987/1988 AND 1994/1995 ..................................................................................... 56

TABLE 3.5 CHANGE IN WATER QUALITY AT GS 8150204 WITH RESPECT TO COPPER CONCENTRATION(MG/L) BETWEEN THE 1987/1988 AND 1994/1995 WET SEASONS .......................................... 57

TABLE 3.6 COMPARISON OF POLLUTANT CONCENTRATIONS AND LOADS AT DYSONS OPEN CUT LANDFORMDRAIN (GS 8150215) BETWEEN 1986/1987, 1987/1988 AND 1997/1998 ............................... 58

TABLE 3.7 RELATIVE RATIOS IN WATER FLOW, SOLUTE CONCENTRATIONS (MG/L) AND CONDUCTIVITY(ΜSCM-1) AT GS 8150097 AND GS 8150200 ........................................................................ 61

TABLE 3.8 STATISTICAL RESULTS FROM FIELD AND LABORATORY REPLICATES OF SUB-SAMPLES OFGS-8150097 COMPOSITE SAMPLE COLLECTED ON THE 23/03/99............................................ 70

TABLE 4.1 COMPARISON OF PIT WATER QUALITY PRIOR TO REHABILITATION WITH POST-REHABILITATIONAND TARGET PIT WATER QUALITY .......................................................................................... 85

TABLE 4.2 RADIOACTIVITY ANALYSIS RESULTS FROM WHITES AND INTERMEDIATE OPEN CUTS..................... 86TABLE 4.3 SOLUTE CONCENTRATIONS (MG/L) AND WATER QUALITY PARAMETERS OF WHITES OPEN CUT,

APRIL 1998 ............................................................................................................................ 88TABLE 4.4 SOLUTE CONCENTRATIONS (MG/L) AND WATER QUALITY PARAMETERS OF INTERMEDIATE

OPEN CUT, APRIL 1998 .......................................................................................................... 88TABLE 4.5 PROFILES OF TEMPERATURE, PH, EC25 AND DISSOLVED OXYGEN AT 1M (AND 0.5M) INTERVALS

TO A DEPTH OF 35 M TAKEN IN WHITES OPEN CUT IN APRIL 1998 ......................................... 90TABLE 4.6 PROFILES OF TEMPERATURE, PH, EC25 AND DISSOLVED OXYGEN AT 1M (AND 0.5M) INTERVALS

TO A DEPTH OF 35M TAKEN IN INTERMEDIATE OPEN CUT IN APRIL 1998 ............................... 91

TABLE 6.1 POST-REHABILITATION MEASURED INFILTRATION, WICKING AND CALCULATED TOTALINFILTRATION FOR WHITES HEAP ......................................................................................... 123

TABLE 6.2 OXYGEN CONCENTRATION (IN VOL%) AT THE BASE OF THE COVER ON WHITES HEAP .................. 124TABLE 6.3 OXYGEN CONCENTRATIONS (IN VOL%) AT THE BASE OF THE COVER ON INTERMEDIATE HEAP ..... 125TABLE 6.4 AVERAGE OXYGEN CONCENTRATION AT THE BASE OF THE COVER IN THE WET AND DRY

SEASONS............................................................................................................................... 126TABLE 6.5 PRE-REHABILITATION OXIDATION RATES IN WHITES HEAP............................................................ 126TABLE 6.6 POST-REHABILITATION OXIDATION RATES IN WHITES HEAP.......................................................... 127TABLE 6.7 PRE-REHABILITATION GORS DUE TO NEAR SURFACE OXIDATION IN INTERMEDIATE HEAP ........... 128TABLE 6.8 CONTRIBUTION TO THE OVERALL OXIDATION RATE IN INTERMEDIATE BEFORE REHABILITATION

OF NEAR SURFACE OXIDATION AND OXIDATION AT DEPTH.................................................... 129TABLE 6.9 POST-REHABILITATION GORS IN INTERMEDIATE HEAP................................................................. 130TABLE 6.10 WHITES HEAP OXIDATION RATES FOR A RANGE OF OXYGEN DIFFUSION COEFFICIENTS.................. 131TABLE 6.11 INTERMEDIATE HEAP OXIDATION RATES FOR A RANGE OF OXYGEN DIFFUSION COEFFICIENTS ...... 131TABLE 6.12 EFFECTIVE DIFFUSION COEFFICIENT OF THE COVER ON WHITES HEAP........................................... 132TABLE 6.13 EFFECTIVE DIFFUSION COEFFICIENT OF THE COVER ON INTERMEDIATE HEAP................................ 132

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TABLE 7.1 ANNUAL NORMALISED CATCHES SUMMARY FOR DECAPOD GENERA. ............................................ 145TABLE 7.2 NORMALISED DECAPOD CATCH SUMMARY FOR THE EAST BRANCH, 1994. DISTANCES ARE

KILOMETRES DOWNSTREAM OF RUM JUNGLE GAUGING STATION GS8150200. .................... 148TABLE 7.3 SAMPLING FREQUENCY DURING THE 1994/1995 MACROINVERTEBRATE SURVEY. ........................ 152TABLE 7.4 METALS IN SEDIMENTS FROM THE FINNISS RIVER (µG/G DW). ..................................................... 166TABLE 7.5 MAXIMUM MEASURED CONCENTRATIONS OF HEAVY METALS IN FILTERED WATER SAMPLES

(µG/L) IN SITES DOWNSTREAM OF THE EAST BRANCH CONFLUENCE IN JANUARY 1998SUBSEQUENT TO THE FIRST FLUSH IN DECEMBER 1997......................................................... 174

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LIST OF PLATES

PLATE 3.1 GAUGING STATION GS 8150097 ..................................................................................................... 30PLATE 3.2 THE INFLOW AND OUTFLOW GAUGE STATION SET-UPS AT THE OPEN CUTS WITH LEVEL

RECORDERS AND SAMPLING STATIONS.................................................................................... 39PLATE 3.3 IRON AND ALUMINIUM CHEMICAL FLOCS OBSERVED AS SURFACE SCUMS IN THE EAST FINNISS

RIVER, APPROXIMATELY 700 METRES DOWNSTREAM OF RUM JUNGLE.................................. 66PLATE 5.1 THE INTERFACE BETWEEN BARE AND VEGETATED AREAS ALONG TRANSECT 2............................. 100PLATE 5.2 SALT EFFLORESCENCE AT THE SURFACE OF A DIEBACK AREA ....................................................... 103PLATE 5.3 AN AREA OF EXPANDING DIEBACK ALONG THE NORTHERN EDGE OF DYSONS OPEN CUT.............. 107PLATE 5.4 SURFACE FINES COLLECTING ON THE UPSLOPE OF THE RECENTLY ADDED CONTOUR BANKS ......... 108PLATE 5.5 LOOKING TOWARDS THE ONLY SIGNIFICANT AREA OF DIEBACK ON WHITES DUMP....................... 110PLATE 5.6 ACID WATERS AT THE EXIT POINT OF THE DRAINAGE FROM DYSONS OPEN CUT ........................... 111PLATE 8.1 LOCATION OF A MIMOSA INFESTATION AND EROSION CONTROL WORKS CONDUCTED ON THE

RUM JUNGLE SITE................................................................................................................. 186PLATE 8.2 THE LOCATION OF ANNUAL HERBICIDE APPLICATIONS ALONG ACCESS TRACKS IN THE RUM

JUNGLE SITE ......................................................................................................................... 189PLATE 8.3 THE LOCATION OF ANNUAL CONTROLLED BURNS UNDERTAKEN AROUND MID-APRIL ON THE

RUM JUNGLE SITE................................................................................................................. 194

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APPENDIX 1 CHEMISTRY OF SOIL, SOIL WATERS AND GRASS SAMPLES OFDYSONS OPEN CUT

TABLE A 1 DEPTH TO COPPER HEAP LEACH WASTE, SURFACE (0–15 CM) SOIL PH AND SURFACE FINEEARTH FRACTION.................................................................................................................. 202

TABLE A 2 THE PH AND ELEMENTAL CONCENTRATION IN 1:5 SOIL: DEIONISED WATER EXTRACTS OFSAMPLES TAKEN FROM BARE AND VEGETATED SITES............................................................ 203

TABLE A 3 THE SOIL SOLUTION PH, EC AND ELEMENTAL CONCENTRATIONS IN THE SURFACE SOIL OFTRANSECT 2 ......................................................................................................................... 204

TABLE A 4 THE ACTIVITY OF SELECTED IONIC SPECIES IN SOIL SOLUTIONS FROM TRANSECT 2 SURFACESAMPLES............................................................................................................................... 205

TABLE A 5 SAMPLING DEPTH, EC, PH AND DTPA-EXTRACTABLE METAL CONTENTS OF SAMPLES TAKENFROM BARE AND VEGETATED AREAS .................................................................................... 206

TABLE A 6 ELEMENTAL TISSUE CONCENTRATIONS IN GRASS SAMPLES TAKEN FROM VEGETATED AREASAND TRANSECTS ACROSS BARE AREA / VEGETATION INTERFACES OF DYSONS OPEN CUTAND VEGETATED AREAS OF WHITES DUMP. ............................................................................. 7

TABLE A 7 THE PH AND ELEMENTAL COMPOSITION OF 1:5 SOIL: DEIONISED WATER EXTRACTS OF SAMPLESTAKEN FROM TRANSECTS ACROSS BARE AREA / VEGETATION INTERFACES .......................... 217

TABLE A 8 SAMPLING DEPTH, EC, PH AND DTPA-EXTRACTABLE METAL CONTENTS OF SAMPLES TAKENFROM TRANSECTS ACROSS BARE AREA / VEGETATION INTERFACES ...................................... 219

TABLE A 9 DEPTH TO COPPER HEAP LEACH WASTE, PH AND NAG PH FOR SELECTED SITES........................... 221TABLE A 10 THE PH AND ELEMENTAL COMPOSITION OF 1:5 SOIL:DEIONISED WATER EXTRACTS OF SAMPLES

TAKEN THROUGH FRESH SOIL PLACED IN A CONTOUR BANK ................................................. 221TABLE A 11 THE EC, PH AND DTPA-EXTRACTABLE METAL CONTENT OF SAMPLES TAKEN THROUGH FRESH

SOIL PLACED IN A CONTOUR BANK........................................................................................ 221TABLE A 12 THE PH AND ELEMENTAL COMPOSITION OF 1:5 SOIL:DEIONISED WATER EXTRACTS OF SAMPLES

FROM ADJOINING BARE AND VEGETATED PORTIONS OF WHITES DUMP ................................ 222TABLE A 13 THE EC, PH AND DTPA-EXTRACTABLE METAL CONTENT OF SAMPLES FROM ADJOINING BARE

AND VEGETATED PORTIONS OF WHITES DUMP ..................................................................... 222

APPENDIX 2 TEMPERATURE AND OXYGEN MEASUREMENTS IN WHITES,INTERMEDIATE AND DYSONS HEAPS.

FIGURE B 1 TEMPERATURE CROSS-SECTIONS MEASURED IN WHITES HEAP ...................................................... 224FIGURE B 2 TEMPERATURE CROSS-SECTIONS MEASURED IN WHITES HEAP ...................................................... 225FIGURE B 3 TEMPERATURE CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP........................................... 226FIGURE B 4 TEMPERATURE CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP........................................... 227FIGURE B 5 TEMPERATURE CROSS-SECTIONS MEASURED IN DYSONS HEAP ..................................................... 228FIGURE B 6 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP.................................... 229FIGURE B 7 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP.................................... 230FIGURE B 8 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP.................................... 231FIGURE B 9 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP.................................... 232FIGURE B 10 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP .................................. 233FIGURE B 11 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN WHITES HEAP .................................. 234FIGURE B 12 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP ....................... 235FIGURE B 13 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP ....................... 236FIGURE B 14 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP ....................... 237FIGURE B 15 OXYGEN CONCENTRATION CROSS-SECTIONS MEASURED IN INTERMEDIATE HEAP ....................... 238FIGURE B 16 OXYGEN CONCENTRATION CROSS-SECTIONS IN DYSONS HEAP .................................................... 239

ACKNOWLEDGEMENTS

The completion of this monitoring report represents the conclusion of a successful multi-disciplinary, multi-agency and cross-government approach to a significant environmentalproblem and also marks the disbandment of the Rum Jungle Monitoring Committee.

The current Chair of the Committee, Rod Applegate, extends his thanks to the variousmembers of the committee who have contributed their considerable professionalism andscientific expertise to a challenging project, which has incorporated differing managementstyles and directions over the last twelve years.

Past and Present Members include:

Karen Powell Department of Industry, Tourism and Resources (formerlyCommonwealth Department of Primary Industries and Energy)

Peter King Department of Industry, Tourism and ResourcesIan Smith Department of Infrastructure, Planning and Environment (formerly

Department of Lands, Planning and Environment)Michael Lawton Department of Infrastructure, Planning and EnvironmentMaria Kraatz (formerly) Department of Lands, Planning and EnvironmentJohn Verhoeven (formerly) Power and Water AuthorityKevin Boland (formerly) Power and Water AuthorityJohn Bennett Australian Nuclear Science and Technology OrganisationJohn Twining Australian Nuclear Science and Technology Organisation

The Committee extends their thanks to the many people who have been involved inmonitoring and maintenance operations at the site over the last twelve years.

Various contributions have also been made over this last five year monitoring period.

John Twining, Scott Markich and Cyrus Edwards are grateful to Dr Karen Coombes of theNT Museum of Applied Arts and Sciences who confirmed or corrected our identifications.

The collected animals were aged by a count of the annual shell rings under transmitted lightby Dr Chris Humphrey (eriss). We also acknowledge his assistance in collection of themussels and in providing expert advice on the biology of the species.

Maria Kraatz and Alan Norrington thank the many people who have contributed to sitemaintenance including Gary Hillen, Col Creaser and Brendan Ewing.

Maria Kraatz also extends her thanks to Rod Applegate for his considerable assistance informulating the discussion regarding future management and monitoring and recognises thatshe just couldn’t have done it without him!

Michael Lawton wishes to thank the numerous staff of the (former) Water ResourcesDivision within the NT Government who contributed to the collection and collation ofhydrographic and water quality data over the life of the project. Also, in particular to MsJayne Hume for her provision of an orderly support service for chemical analysis.

The editor would like to thank Rod Applegate, Peter King, Jackie Stanger and all the authorsfor their assistance in getting the report to publication.

Rum Jungle Monitoring Report 1993-1998 1

1. Summary

1.1. INTRODUCTION

This report documents monitoring activities at the Rum Jungle rehabilitation site for

the period July 1993 to June 1998. The Rum Jungle mine operated between 1954

and 1971 and while it was Australia’s first uranium mine, also produced quantities of

copper, nickel and lead. The site is located 85 km south of Darwin in the headwaters

of the East Branch of the Finniss River. Mining at the site led to significant

environmental impacts due to the long term generation of acid drainage.

This report presents:

• A brief re-evaluation of the original rehabilitation objectives and standards used at

Rum Jungle in the context of contemporary rehabilitation standards and current

land use options;

• Findings of monitoring conducted between 1993 and 1998 on surface water

quality, water quality in the open cut water bodies, vegetation die-back on Dysons

Open Cut, effectiveness of covers on the overburden heaps, measures of

ecological impact in the Finniss River and site integrity issues;

• The final assessment of the Rum Jungle Monitoring Committee (RJMC) based on

12 years of monitoring between 1986 and 1998, including a recommendation that

limited monitoring continues based solely on statutory responsibilities; and

• Suggestions for further areas of work to address largely unresolved scientific

matters, which do not relate to the assessment of rehabilitation against the

original objectives.

1.2. MANAGEMENT AND MONITORING (CHAPTER 2)

This chapter briefly summarises early environmental impacts associated with the

abandoned Rum Jungle mine, the rehabilitation program undertaken between 1982-

1986, and results of two monitoring periods between 1986-1988 and 1988-1993. The

results of monitoring undertaken between 1993-1998 are outlined in Chapters 3 to 8,


including suggestions for further work to address scientific questions about

rehabilitation behaviour.

Twelve years of monitoring at Rum Jungle have demonstrated the continuing

success of rehabilitation against the original objectives. Given improved

understanding of Acid Mine Drainage and increased environmental standards and

expectations, however, there has been a tendency to measure success against more

contemporary standards. Regardless of any amount of public investment, it should

be recognised that Rum Jungle will remain a contaminated site. Environmentally or

socially acceptable limits to the amount of contamination emanating from the site will

to some extent change with time and context. The degree to which public investment

can respond to such change will need to be clearly defined and appropriately

justified against well considered options for the site’s final land use; as will be the

level and scope of any future management and monitoring. These land use options

currently include a continuation of the site’s status as Crown Land under a Restricted

Use Area declaration, mining of Browns deposit adjacent to and possibly within Rum

Jungle and/or transfer of the site to Traditional Owners under the Finniss River Land

Claim.

In recognition that rehabilitation continues to meet its original objectives and in the

absence of any change in land tenure, the RJMC recommends that future monitoring

and management is limited to that required by statutory obligations. It is also

recommended that as the role of the Committee has now been fulfilled, its operation

should cease.

1.3. SURFACE WATER MONITORING (CHAPTER 3)

The surface water monitoring program for the 1993-1998 period has assessed the

on-going effectiveness of the rehabilitation in terms of pollutant loads discharged

from the site. Both hydrological and physico-chemical data are presented to show

how contaminant loads pre- and post-rehabilitation have performed in relation to the

rehabilitation objectives of contaminant reduction. In addition, there is commentary

on the schedule (on a time and hydrological basis) of load export from the former


minesite to the river system. Improvements in various water quality parameters are

discussed.

Hydrological and water quality data were collected at a number of gauge stations

including GS 8150097 and GS 8150200 on the East Branch of the Finniss River,

GS 8150212 and GS 8150213 at the former minesite and GS 8150204 on the main

Finniss River downstream of its confluence with the East Branch. Annual load

estimates are presented for the main metal pollutants found at GS 8150097 and

include copper, zinc and manganese – sulfate load estimates are also presented. pH

data is included to demonstrate the reduction in acid discharge from Rum Jungle. A

post-rehabilitation median value of pH 6.3 shows a marked improvement from a pre-

rehabilitation median value of pH 4.2. This demonstrates a return to circum-neutral

levels and provides for a synergistic attenuation in metal toxicity as metal

contaminant concentrations are similarly reduced.

An assessment of the contamination profile downstream of Rum Jungle was

conducted along a reach of the East Branch from GS 8150097 to GS 8150200. An

hypothesis was outlined in the previous Monitoring Report (Kraatz 1998) that

elevated levels of calcium, magnesium, sulfate, copper, manganese and nickel found

at G 8150097 relative to GS 8150200 were a result of contaminated groundwater in-

flow entering downstream of GS 8150200. Further investigations found this to be

unsubstantiated.

Suggestions for further work, arising from the surface water monitoring program

include:

• Maintenance of annual contaminant load estimates at GS 8150097;

• Consolidation of the contaminant status of fluvial sediments in the East Branch

and Finniss Rivers; and

• Characterise groundwater processes on-site to allow for proper reconciliation of

the contaminant loads exported from the site and measured in surface flows at

GS 8150097.


1.4. WATER QUALITY IN WHITES AND INTERMEDIATE OPEN CUT WATERBODIES (CHAPTER 4)

The monitoring program to assess the water quality of the open cuts in 1993-1998

was similar to that adopted in 1992/1993 and reported previously (Kraatz 1998). This

included regular monitoring, fortnightly to 1995, but at a greater timestep for the

remainder of the monitoring period. The water quality profile in each water body was

monitored in terms of physical-chemical parameters including temperature, pH,

copper, manganese, zinc and sulfate. In order to consolidate the understanding

gained earlier about the contaminant transport processes from the open cuts, gauge

stations were established to continuously monitor flow and water quality at the inflow

and outflow from the open cuts. Contaminant load estimates at these stations were

reconciled with estimates made from the profile data. Given the inventory of

contamination that was resident in Whites Open Cut and the processes/rates

whereby this material is transported from the site, an estimate is made of when this

repository will be exhausted and the open cuts become non-contributors to the

overall loads from the site.

The ‘exposure’ of the untreated water at the base of Whites to seasonal water flush

represented a new containment regime at the former minesite and one not

anticipated by the rehabilitation process. For that reason it was deemed appropriate

to undertake radiological analyses on the waters in the open cuts. Gross alpha and

beta determinations were undertaken in 1996 for surface and hypolimnetic waters in

each water body and indicated elevated radioactivity at the bottom of Whites and

minor transport of this contamination to surface waters. Radium 226 levels were also

determined and these analyses are discussed in relation to the Drinking Water

Guidelines (NH&MRC 2001).

There is some discussion on the rehabilitation objectives for the open cuts and how

they have been met. The lack of accurate prediction for the interactions of residual

untreated hypolimnetic waters with either annual fresh water inflows to Whites or

natural vertical mixing processes that operate in the cooler dry season months

represents a failure in the rehabilitation approach. This has led to both a higher than

anticipated export of contaminants from Whites over the period since rehabilitation


and also the seasonal acidification of surface waters in Whites, rendering this water

unfit for most prospective uses. However, each of these consequences is projected

to be temporary as the inventory of untreated water in Whites Open Cut is exhausted

over the next few years.

Suggestions for future work arising from this monitoring period include:

• Update status of the stratification profiles for each open cut;

• Investigate issue of contamination (radioactivity/sediments) at the base of

White's open cut; and

• Model enhanced flushing of recessional flows from site by accessing 'clean'

water from Intermediate pit.

1.5. VEGETATION DIEBACK ON DYSONS OPEN CUT, IMPLICATIONS,CAUSAL MECHANISMS AND OPTIONS FOR REMEDIATION (CHAPTER 5)

Vegetation dieback has been occurring on Dysons Open cut for several years. This

chapter assesses the causes of the dieback and implications for future remediation.

A sampling program of Dysons open cut was undertaken whereby soil and

vegetation samples were analysed in terms of chemical and physical characteristics.

High levels of copper were found at the site resulting in plant deaths at areas where

soil depth was shallowest. Thus inadequate capping of the copper Heap leach waste

has resulted in movement of the copper to overlying soil layers. In addition, salt

efflorescence at the surface occurs in many of the bare areas, which is the result of

accumulating sulfate salts. This phenomenon also occurs due to contamination by

the copper Heap, leach waste materials.

Three options for overcoming this problem have been put forward; do nothing, cover

with rock mulch or completely reinstall the capping with appropriate materials. These

options are discussed in terms of feasibility and cost for rehabilitating the site to

prevent further dieback in the future.


1.6. EFFECTIVENESS OF COVERS ON THE OVERBURDEN HEAPS(CHAPTER 6)

This chapter aims to calculate the effectiveness of the covers placed on the

overburden heaps in reducing pyrite oxidation and water infiltration rates. These

parameters are important as the oxidation of pyrite is the primary pollutant

generation mechanism within the heaps and the rate of water infiltration determines

the rate at which these pollutants are removed from the heaps.

During the rehabilitation program an engineered cover, which included a compacted

clay layer, was placed on each of the overburden heaps. Measurements of pore gas

oxygen concentration, temperature and water infiltration were made both before and

after rehabilitation, and it is these measurements which have been used to calculate

the effectiveness of the rehabilitation measures.

The results showed an increased infiltration rate into Whites heap compared to the

previous monitoring period. It is concluded that the cover is now a less effective

barrier to water flow into the heap. Oxygen concentration and temperature

measurements indicated that placement of the cover had reduced the overall

oxidation rate of Whites heap by a factor of three and the overall oxidation rate of

Intermediate heap by a factor of two. The implications of the measurements are

discussed and suggestions for further work are included. The suggestions focus on

determining the reasons for the deterioration in cover performance in recent years

and assessing the potential ecological impact on the Finniss River of this

deterioration.

1.7. MEASURES OF ECOLOGICAL IMPACT IN THE FINNISS RIVERDOWNSTREAM OF THE RUM JUNGLE REHABILITATED SITE, 1993-98.(CHAPTER 7)

Waste from the former mine site entered the Finniss River system, this resulted in

the death of all aquatic life in the East Branch between the former mine site and 8.5

km downstream. Also, in the main Finniss River system a greatly reduced

biodiversity in aquatic life was found for 15 km downstream (Kraatz and Applegate,


1992). Attempts to remediate this situation were made in the early-mid 1980’s. This

chapter assesses the success of the remediation through a monitoring program of

benthic and epi-benthic macro-invertebrates, as well as an assessment of archival

monitoring of bioavailable pollution using freshwater mussels. In addition, a study of

the first annual flush was conducted to determine the impact of polluted waters on

the Finniss River system.

Results showed a decline in decapod populations in the zone of the Finniss River

that was previously most affected by pollution. Fish and crustacean deaths were

observed in the East Branch during the first flush and mussels were not found

downstream of the East Branch confluence indicating a contaminant gradient still

persists within the system. However, overall conditions have improved in the Finniss

River system since rehabilitation of the site.

These improvements, though, fall short of contemporary recommended national

water quality guidelines, thus further monitoring is suggested using biological indices

to measure the impacts on the aquatic ecosystem. Specifically, the following are

suggested in order of priority:

• Ecological risk assessment and water quality modelling;

• Macroinvertebrate studies in the main river;

• Mussel translocation experiments and sediment ecotoxicology;

• Benthic algae and bacteria; and

• Shrimp translocation experiments with seasonal variation.

1.8. SITE INTEGRITY (CHAPTER 8)

Qualitative assessments and management of site integrity continued at Rum Jungle

and focused on weeds, erosion, wildfire, site access and feral animals. A summary

of works undertaken between July 1993 and June 1998 is provided.

Ongoing management and maintenance of the integrity of rehabilitated structures

can largely be achieved by meeting current legislative requirements in relation to fire

and weeds.


The Committee does recommend that statutory obligations in relation to fire and

weed management continue to be met by the landholder and that while the site

remains Vacant Crown Land the Restricted Use Area provisions of the Soil

Conservation Land Act remain in force to control access to the site.

In addition, it is suggested that a more detailed assessment of the longer term

persistence of improved pastures and stability of erosion control works is planned

within the context of broader monitoring, management and land use issues affecting

the site. Depending on the evolution of these issues, it is suggested that this

assessment be undertaken by 2009, 25 years from the commencement of

rehabilitation.


2. MANAGEMENT AND MONITORING: A discussion of issuesaffecting future land use, management and monitoring

M KRAATZM4K Environmental Consulting

Casuarina, NT.

2.1. INTRODUCTION

The Rum Jungle mine operated between the 1954 and 1971 and was Australia’s first

uranium mine. It produced approximately 3,500 tonnes of uranium, 20,000 tonnes of

copper and smaller quantities of nickel and lead. The site is located 85 km south of

Darwin and in the headwaters of the East Branch of the Finniss River, which flows

through the site (Figures 2.1 and 2.2). Mining at the site led to the occurrence of acid

drainage that severely impacted the East Branch of the Finniss River.

This chapter briefly summarises early environmental impacts associated with the

abandoned Rum Jungle mine site, the rehabilitation program undertaken between

1982 and 1986, and results of two monitoring periods between 1986-1988 and 1988-

1993. Further detail can be found in Allen and Verhoeven (1986), Kraatz and

Applegate (1992) and Kraatz (1998). Monitoring undertaken between 1993 and 1998

is the subject of this report and is addressed in detail in subsequent chapters.

Recommendations for future management and monitoring are made as well as

suggestions for further work to address unresolved scientific issues regarding

rehabilitation behaviour.

In light of 12 years of monitoring, this chapter discusses issues that have been

considered in determining the level of commitment appropriate for any future

monitoring and maintenance at the site. This includes consideration of the relevance

of contemporary standards to measuring rehabilitation success at Rum Jungle and

issues associated with future land use options.


2.2. ENVIRONMENTAL IMPACTS

Due to the presence of sulfide bearing overburden, mining at Rum Jungle led to acid

drainage and the mobilisation of heavy metals. At the cessation of mining, and in

accordance with legislation at that time, the company was under no obligation to

remediate existing environmental impacts or prevent further impact. The resulting

environmental problems have been described in detail in a number of reports (Davy

1975, Department of the Northern Territory 1978), and were summarised by Kraatz

(1998: 7): “The generation of sulfuric acid and the associated release of heavy

metals from the Overburden Heaps resulted in the destruction of all flora and fauna

in the East Branch for 8.5 km downstream of the former mine site to the confluence

with the Finniss River. Reduced bio-diversity was also evident in the Finniss River for

a further 15 km. In addition, large quantities of low-level radio-nuclides flowed from

the tailings dam and were spread down the river system and over 100 km2 of

floodplain.”

Increased concern over the continuing environmental impact at Rum Jungle led to a

minor clean-up operation in the late 1970’s. The initial clean up was conducted.

However in 1977, the measures were largely aesthetic and not aimed at reducing the

ongoing generation of pollutants. A number of strategies had been proposed

worldwide to counter acid mine drainage (AMD), but none of these had been tested.

At this time, a working group from the Commonwealth and Northern Territory

Administration was established to develop a series of strategies for the rehabilitation

of the Rum Jungle site using the most recent expertise and technologies.


Figure 2.1 Location of the Rum Jungle rehabilitation site.


Figure 2.2 Rum Jungle Site Plan

2.3. REHABILITATION AND MONITORING 1982-1998

Rehabilitation objectives

In 1982, a financial assistance agreement was signed between the Federal and

Northern Territory Governments for rehabilitation at Rum Jungle. The agreement set

in place an $M18.6 program incorporating a four year rehabilitation and two year

monitoring period (1982-1986 and 1986-1988 respectively). The rehabilitation

objectives, primary treatments and additional standards set are outlined in Table 2.1.

These objectives reflected contemporary thinking in mine site rehabilitation and were

considered appropriate and practical considering the scope of the problems to be

dealt with and the level of resources available. Further detail on the program is

outlined in the Final Project Report (Allen and Verhoeven 1986).


Table 2.1 Objectives, results achieved, primary treatments and standards adopted for the Rum Jungle Rehabilitation Project (Allen andVerhoeven 1986, Richards et al 1996)

OBJECTIVES RESULT PRIMARY TREATMENTS STANDARDS

1. Achieve a major reduction insurface water pollution, aimedat reducing the average annualquantities of copper, zinc andmanganese by 70%, 70% and56% respectively, as measuredat the confluence of the EastBranch of the Finniss River andthe Finniss River.

2. Reduce pollution levels ofWhites and Intermediate OpenCuts.

3. Reduce public health hazards,including radiation levels at thesite at least to the standards setout in the Code of Practice onRadiation Protection in theMining and Milling ofRadioactive Ores (AGPS 1980).

4. Implement aestheticimprovements includingrevegetation (Allen andVerhoeven 1986).

Objective Achieved.Based on improvements in medianconcentration of specifiedcontaminants (Copper, zinc andmanganese loads reduced by 95%,80% and 70% respectively.) from preto post rehabilitation as measured atGS 8150097, 5.6 km downstream ofthe former minesite. Refer to Chapter3.

Objective Achieved.Substantial reductions in pollution in

Whites and almost total eliminationin Intermediate. Refer to Chapter 4.

Objective achieved as measured in1986.Refer to chapter 8

Objective AchievedRefer to chapter 8

• The treatment of acid waterscontained within Whites OpenCut and re-establishment of wetseason flushing of Whites andIntermediate Open Cuts.

• Capping of acid generatingmaterial with low permeabilityclay material and pore breakinglayers to restrict the ingress ofwater and oxygen.

• Re-shaping of Heaps andconstruction of soil conservationworks to facilitate waterdrainage, minimise ponding andprevent erosion.

• The removal of low-levelradionuclides (from the TailingsDam and East Branch of theFinniss River) and copper Heapleach material and theirplacement and capping withinDysons Open Cut.

• Revegetation using introduced pasture species.

• Water below the confluence of themain Finniss and the East Branch tomeet National Health and MedicalResearch Council standards fordrinking water.

• Water quality in the East Branch toinclude the reductions in metalsloads prescribed in Objective 1.

• Design life for rehabilitation to be100 years.

• Radiation emission and radonemanation to meet standardsprescribed by the NorthernTerritory Department of Health.

• Flora and fauna populations to besimilar to those of adjacent areas ofbush and the work not to result inintroduction of exotic species to thearea.

• Post-rehabilitation standards toallow recreational land use, withsome constraints.


Rehabilitation standards

The standards used for rehabilitation are not often discussed in post-rehabilitation

literature and a brief discussion is warranted. While some of the standards continue

to be relevant, others are no longer considered appropriate or are at odds with the

primary treatments used in rehabilitation.

Drinking water standards have not been accepted as relevant to ecological recovery

of aquatic ecosystems for some time and percentage reductions in contaminant

loads are not related to specific levels of ecological improvement. A great deal of

monitoring effort at Rum Jungle has therefore centred on measuring the impacts of

rehabilitation against more recently accepted ecological criteria (Chapter 7).

Changing standards for measuring the success of rehabilitation are discussed in

more detail below.

Soil conservation structures were constructed to reach a design life of 100 years and

this remains an appropriate and feasible standard.

A Radiation Safety Regime (Hewson 1984) was in place to minimise radiological

hazard throughout the rehabilitation operation. A radiation monitoring report

(Harrington 1985), whilst not specifically referring to Department of Health standards,

indicates that worker exposure to radiation throughout the transfer of tailings material

was low, due in part to the short period of time taken for the transfer. The meeting of

radiological objectives is discussed in Chapter 8.

The standard relating to flora and fauna populations was at odds with the primary

treatment of using introduced pasture species. Flora and fauna populations were to

be similar to those of adjacent areas, however revegetation was primarily undertaken

for erosion control and aesthetic improvement. Rehabilitated areas were planted

using improved pastures in order to rapidly establish a vegetative cover and prevent

erosion. Trees were neither planted nor encouraged on the overburden heaps and

fertilisation and slashing were undertaken in the first few years to ensure vigorous

pasture growth and encourage development of an “A” horizon. The invasion of some


rehabilitated areas by weeds has been an ongoing issue (see Chapter 8) and it is

likely that this was triggered by the use of contaminated topsoil during rehabilitation.

Under these conditions, it was unlikely that similar flora and fauna populations would

establish at the site in any time frame without significant intervention.

The final land use remains an ongoing issue and is discussed in detail below. It is

unlikely that recreational land use will ever be a viable usage of the site.

Monitoring arrangements

At the completion of rehabilitation, the Rum Jungle Monitoring Committee (RJMC)

was established under the financial assistance agreement and assumed

responsibility for implementation of the 1986-1988 monitoring program and

assessment and coordination of future monitoring. The committee reports to the

Commonwealth Department of Industry, Tourism and Resources (DITR) and

consists of representatives from the Department of Infrastructure, Planning and

Environment (DIPE), the Australian Nuclear Science and Technology Organisation

(ANSTO), and Department of Industry, Tourism and Resources (DITR).

Monitoring was undertaken at the site between 1988 and 1998 through two separate

funding arrangements between the Federal and Northern Territory Governments.

Total expenditure on the site since completion of rehabilitation is shown below (Table

2.2).


Table 2.2 Total expenditure on monitoring and maintenance at the Rum Jungle site sincecompletion of rehabilitation.

Expenditure ($)Monitoringperiod Agencies Commonwealth Total

Reported

1986-1988 1,312,737 1,312,737* Kraatz and Applegate(1992)

1988-1993 118,800 127,000 245,800 Kraatz (1998)

1993-1998 584,250 931,250 1,515,500 Pidsley (2002)

TOTAL ($) 703,050 2,370,987 3,074,037

* Included administration costs from completion of monitoring project and high maintenance costs immediately

post-rehabilitation in 1986/87.

1986-1988 monitoring recommendations

The Site Management Plan compiled in 1988 (Verhoeven) states:

“Results of the monitoring program show that as an indicator of short term success

the objectives as set out in the Agreement appear to have been achieved. While

pollution still exists, it is important to emphasise that the rehabilitation works were

never intended or expected to eliminate all of the pollution sources. Minor sources

will remain, but the effect will be very small by comparison with that prior to

rehabilitation”.

The Plan goes on to describe two remaining areas of concern: below average

rainfalls during and after rehabilitation and the predicted slow environmental

response of some areas of the site to rehabilitation. Testing the longer-term

effectiveness of rehabilitation, particularly through periods of at least average rainfall,

became the primary justification for the two subsequent monitoring periods.

The Plan recommended continuing monitoring of:

• Surface water quality and hydrology in the East Finniss River;

• Water quality in Whites and Intermediate Open Cut water bodies;

• The effectiveness of covers on the Overburden Heaps;

• General site integrity; and


• A flora and fauna survey to be undertaken in 1993 for comparison with Davy’s

pre-rehabilitation survey (1975).

“When examining the question of the need for and scope of further monitoring, it was

considered important to separate the monitoring required to verify the continuing

success and integrity of the rehabilitation works from monitoring required for other

research purposes” Verhoeven (1988).

1988-1993 monitoring recommendations

Monitoring through this period continued to demonstrate the short-term success of

rehabilitation according to the original objectives. The RJMC was concerned that it

was still not possible to predict medium to long term effectiveness with regard to

broader environmental outcomes. Previous monitoring, an improved understanding

of AMD mechanisms, and the development of more sophisticated measures of

rehabilitation success pointed to shortcomings in the original monitoring program that

it was thought should be rectified. In addition, rainfall throughout the 1988-1993

period was mainly average to below average, and rehabilitation works had therefore

still not been tested by significant rainfalls.

The main areas of concern relating to the longer-term effectiveness of the

rehabilitation were:

• “The effectiveness of the cover seal on Whites and Intermediate Overburden

Heaps in inhibiting pollution generation within these Heaps;

• Long term, time dependent changes in pollution loads exiting the base of Whites

and Intermediate Overburden Heaps;

• The contribution of pollution loads in the East Finniss River from Whites and

Intermediate Open Cuts and how this may change with time;

• The contribution of Dysons Overburden Heap and the effectiveness of its different

cover system;

• The water quality in both the East Branch and the Finniss River downstream of

their confluence; and

• The ecological effects of the pollutants downstream of Rum Jungle and the

response to rehabilitation” (Kraatz 1998:15).


Groundwater hydrology studies by Gibson (1998) concluded that it was not possible

to make reasonable estimates of groundwater pollutant loads. The following

recommendations for further groundwater investigations were made:

• “Measurements of the stratification of water quality be attempted;

• Further measurements of soil conductivity be made, to establish the size and

position of the plume of polluted water;

• Efforts be made to estimate the water velocity in the plume, possibly taking

stratification into account; and

• An attempt be made to measure the pollutant concentrations in the pore water in

the Heap, to establish the total inventory and its annual rate of release” (Gibson

1998:36).

These investigations were not carried out primarily due to the tragic death of Dr

David Gibson. Dr Gibson was an integral part of the groundwater hydrology program

and his skills were unable to be replaced within the period of the project.

A study regarding remediation options on Dysons Open Cut became necessary

following the die-back of vegetation on the highest slopes of Dysons Open Cut land

form.

1993-1998 monitoring

An additional five-year monitoring period was established in 1993 to address the

above concerns and as per the cost sharing arrangement detailed in Table 2.3. This

report presents the findings of that work which relates to:

• Water quality within the open cuts and the East Branch and main channel of the

Finniss River (Chapters 3 and 4);

• Investigations into the implications, causal mechanisms and options for

remediation of vegetation dieback on the Dysons Open Cut landform (Chapter 5);

• The effectiveness of covers on the Overburden Heaps (Chapter 6);

• Biological monitoring in the East Branch and main channel of the Finniss River,

including macro-invertebrate and decapod surveys, archival monitoring of mussel

shell laminations and an assessment of the biological effects of the first flush

within the Finniss River (Chapter 7); and


• Site integrity, including qualitative assessments of surface stability, pasture

status, fire management and other site maintenance issues (Chapter 8).


Table 2.3 Original cost sharing arrangements over the five-year monitoring period

As per the “Financial assistance agreement for the monitoring and maintenance of the Rum Junglemine between the Commonwealth of Australia and the Northern Territory of Australia” (1994)

ACTIVITY SOURCE 1993/94 1994/95 1995/96 1996/97 1998/99 TOTAL

C'wealth $ 33,000 $ 20,000 $ 6,000 $ 6,000 $ 6,000 $ 71,000Water Quality FinnissRiver System PAWA $ 20,000 $ 20,000 $ 20,000 $ 15,000 $ 15,000 $ 90,000

TOTAL $ 53,000 $ 40,000 $ 26,000 $ 21,000 $ 21,000 $ 161,000

C'wealth $ 55,000 $ 20,000 $ 5,000 $ 5,000 $ 5,000 $ 90,000Water quality open cuts PAWA $ 5,000 $ 5,000 $ 15,000 $ 10,000 $ 10,000 $ 65,000

TOTAL $ 70,000 $ 35,000 $ 20,000 $ 15,000 $ 15,000 $ 155,000

C'wealth $ 55,000 $ 50,000 $ - $ 10,000 $ - $ 115,000Ecology Finniss RiverSystem ANSTO $ 0,000 $ 50,000 $ - $ 15,000 $ - $ 115,000

TOTAL $ 105,000 $ 100,000 $ - $ 25,000 $ - $ 230,000

C'wealth $ 40,000 $ 40,000 $ 40,000 $ 30,000 $ 30,000 $ 180,000

ANSTO $ 5,000 $ 15,000 $ 15,000 $ 15,000 $ 15,000 $ 75,000Overburden heaps PAWA $ 1,000 $ 1,000 $ 1,000 $ 1,000 $ 1,000 $ 5,000

TOTAL $ 56,000 $ 56,000 $ 56,000 $ 46,000 $ 6,000 $ 260,000

C'wealth $ 40,750 $ 40,750 $ 40,750 $ 40,750 $ 40,750 $ 203,750

ANSTO $ 12,750 $ 12,750 $ 12,750 $ 12,750 $ 12,750 $ 63,750Groundwater monitoring PAWA/CCNT $ 5,000 $ 5,000 $ 5,000 $ 5,000 $ 5,000 $ 25,000

TOTAL $ 58,500 $ 8,500 $ 58,500 $ 58,500 $ 58,500 $ 292,500

C'wealth $ - $ 38,000 $ 40,000 $ 40,000 $ 40,000 $ 158,000

ANSTO $ - $ 16,000 $ 16,000 $ 16,000 $ 16,000 $ 64,000Dysons OverburdenHeap PAWA/CCNT $ - $ 6,000 $ 6,000 $ 6,000 $ 6,000 $ 24,000

TOTAL $ - $ 60,000 $ 62,000 $ 62,000 $ 62,000 $ 246,000

C'wealth $ 10,000 $ 5,000 $ 5,000 $ 5,000 $ 5,000 $ 30,000Site integrity CCNT $ 1,500 $ 1,500 $ 1,500 $ 1,500 $ 1,500 $ 7,500

TOTAL $ 11,500 $ 6,500 $ 6,500 $ 6,500 $ 6,500 $ 37,500

C'wealth $ 10,500 $ 11,500 $ 8,500 $ 8,500 $ 8,500 $ 47,500Site maintenance CCNT $ 8,000 $ 8,000 $ 6,000 $ 6,000 $ 6,000 $ 34,000

TOTAL $ 18,500 $ 19,500 $ 14,500 $ 14,500 $ 14,500 $ 81,500

Interpretation CCNT $ 14,000 $ 500 $ 500 $ 500 $ 500 $ 16,000

5 year report C'wealth $ 17,000 $ - $ - $ - $ 19,000 $ 36,000TOTALCOMMONWEALTH $ 261,250 $ 225,250 $ 145,250 $ 145,250 $ 154,250 $ 931,250

TOTAL AGENCIES $ 142,250 $ 150,750 $ 98,750 $ 103,750 $ 88,750 $ 584,250


2.4. CONTEXTUAL ISSUES FOR FUTURE MANAGEMENT AND MONITORING

Contemporary standards

A growing issue in the development of previous monitoring programs by the RJMC

has been the tendency to measure success at Rum Jungle against contemporary

mine rehabilitation standards on water quality standards, versus those against which

the rehabilitation was originally designed to meet.

Rum Jungle remains a contaminated site. However, using contemporary standards

to assess rehabilitation the following points are notable:

• The rehabilitated environment requires ongoing management to minimise the

impacts of erosion, fire and weeds;

• The environment has not been returned to a state resembling either the

surrounding or the pre-mining environment;

• Water quality on-site and immediately downstream of the site is regularly of a

quality that exceeds recommended concentrations for the protection of

freshwater ecosystems as outlined in national water quality guidelines (ANZECC

1992; ANZECC and ARMCANZ 2001). This water quality retards the

establishment of a fully functional aquatic system in the East Branch of the

Finniss River; and

• Impacts from the site are restricted to the East Branch of the Finniss River.

Investment made in the rehabilitation of the former Rum Jungle mine site is

commensurate with contemporary expenditure on rehabilitation of other mine sites.

Harries (1997) determined that approximately $91,000 per hectare was spent on

rehabilitation at Rum Jungle, which compares to an average $100,000 per hectare

spent on other historic sites across Australia. Given the long term potential for acid

drainage, these sites are recognised as “a large liability for governments and the

community” (Harries 1997: 39). Harries also notes that “there is considerable

uncertainty about what constitutes an effective strategy for managing potentially acid


generating wastes…” and “…there is a lack of available information to show what is

required to ensure that rehabilitation will achieve the required level of isolation and

long term effectiveness”. This situation still exists 20 years after the Rum Jungle

project was planned.

In considering recommendations for future monitoring and maintenance the RJMC

has considered:

• The standards used to ultimately measure the success of rehabilitation. Should

contemporary standards be used to any extent, this must be justified in terms of

meeting a required final land use;

• The time at which monitoring efforts should cease or be significantly reduced,

notwithstanding this arbitrarily occurring due to a lack of resources. Monitoring

has now been undertaken for 12 years and its scope has not been significantly

reduced in that time. It is considered that the end point for formal on-site

monitoring has now been reached and ongoing management and monitoring at

the site should limited to that required by existing Northern Territory statutes; and

• Monitoring activities essential for measuring success against the desired

rehabilitation objectives, versus those considered desirable for research

purposes. Rum Jungle provides excellent opportunities for filling gaps in

knowledge about AMD highlighted by Harries (1997), but any public expenditure

solely for research at Rum Jungle cannot be justified by the RJMC. Other sources

of investment may need to be identified by proponents interested in pursuing

areas of work suggested in subsequent chapters that relate to unresolved

scientific issues.

Final land use

One of the difficulties is that even for modern mining operations there are no

standard criteria for determining when and if rehabilitation is complete. In 1996 the

Australian Minerals Industry adopted a Code for Environmental Management which

stated that mining companies should “periodically review the rehabilitation and

decommissioning strategies over the life of the operation to incorporate changing

legislative requirements, public expectations and environmental and cultural heritage

information” (Minerals Council of Australia 1996:9). It is these drivers which have led


to the changing interpretation of how complete or acceptable the measures at Rum

Jungle have been.

As more monitoring has been undertaken at Rum Jungle, the need for longer-term

assessment of rehabilitation has been recognised. What is not clear, however, is just

what should be accepted as ‘long term’. Much of the recent literature recognises the

need for long term planning and monitoring (Minerals Council of Australia 1996, EPA

1995) and particularly as it relates to acid drainage (Harries 1997), but none of these

attempts to define what this actually means.

Failing the use of specific criteria or time frames, a practical approach may be

adopted whereby “rehabilitation can be considered successful when the site can be

managed for its designated land use without any greater management inputs than

other land in the area being used for a similar purpose” (EPA 1995: 30). This

approach relies on a fairly precise definition of the ‘final’ land use.

A definition of desired land use at Rum Jungle was attempted in 1988 with the

development of a Site Management Plan (Verhoeven 1988). Within the constraints

imposed by maintaining the integrity of rehabilitated structures and uncertainty

regarding the maintenance of good water quality within the open cuts, the plan

considered tourism, research, grazing and mining as potential land use options. Any

more detailed consideration of the final land use was overridden, however, by

uncertainty regarding the outcome of the Finniss River Land Claim. The situation is

also now further complicated by the potential development of the Browns Project

immediately to the west of Rum Jungle and the possibility that this development may

incorporate elements of the rehabilitated site.

Finniss River land claim

Kraatz (1998: 12) summarised the situation regarding the Claim:

“Title to the Rum Jungle rehabilitation site was vested in the Northern Territory

following self government in 1978. In 1981, however, the site was recommended for

grant to an Aboriginal Land Trust as part of Area 4 of the Finniss River Land Claim.

Management and monitoring issues associated with Rum Jungle were outlined in


various detriment submissions developed by the NT Government and included those

described in the Site Management plan (Verhoeven 1988).”

In general, there was concern whether the Commonwealth and NT Government

interests in the Rum Jungle project could be sufficiently protected. The NT

Government thus recommended that before any grant of land was made over the

site, a prior formal agreement should be made with the Land Trust. Protecting

“…Territory and Commonwealth rights to gain access to the Rum Jungle areas for

maintenance and monitoring and restricting land usage by traditional owners in

accordance with recommendations made in the Plan” (Verhoeven 1988). A proposal

for a draft agreement with the Finniss River Land Claimants was developed along

these lines in 1992, but was not further pursued. Title to the majority of Area 4 was

transferred to the Traditional Owners but is still subject to future claim.

The status of land ownership has again been bought into focus in previous years due

to the potential development of Browns deposit.

Browns Project

Exploratory drilling undertaken by Compass Resources under an Exploration

Licence granted in 1989 has led to the development of the Browns Project

immediately to the west of Rum Jungle. Browns contains globally significant deposits

of lead, cobalt, nickel and copper and is currently planned to be in production by

2003.

Whilst Browns Stage 1 pit is located just on the western boundary of the Rum Jungle

Restricted Use Area on Northern Territory freehold land, a potential extension pit

stretches across to Intermediate and Whites Open Cuts. Waste rock may also be

incorporated with the existing overburden heaps and possibly extend further into the

site. Development of the latter would require agreement with the Land Trust if the

site had been transferred from the NT Government under the Land Claim.

The potential extension of mining operations into the existing Restricted Use Area

will also obviously have significant ramifications for existing rehabilitation measures


and most possibly for downstream water quality. There are precedents in Australia

where a modern mining operation is being undertaken over historic rehabilitated

sites where old workings are re-worked using modern, more efficient mining and

waste management technologies. “The final environmental impact can be lower if a

responsible operator rehabilitates part of an abandoned site than if the whole site

remains abandoned.” (Harries 1997: 40). Whilst Rum Jungle presents a particularly

unique situation, it is possible that contaminant production may be reduced if

pollutants within the open cuts can be feasibly removed from the annual wet season

flushing process as part of an extended mining operation. The realisation of this

scenario is, however, contingent on many factors.

If the development of Browns Project progresses as planned, monitoring results

relating to downstream water quality in the East Branch of the Finniss River will

become particularly important. If and when mining commences, the Northern

Territory Water Act, and its Beneficial Use provisions will be applied. This Act

restricts and controls the way in which water quality can be affected and prohibits the

pollution of waterways, unless specifically authorised through the issue of a Waste

Discharge Licence.

Under the Water Act, Beneficial Uses (or environmental values) can be declared to

define the community’s “preferred useability of the water resources and define the

long term consequences of land and water use practices that we want to achieve”

(DLPE 1997). Beneficial Uses are not scientifically or data based, but rather are

determined through the involvement of Government, industry, landholders,

environmental action groups and the community. A unique aspect of the Beneficial

Use process will be the need to accommodate community expectations and the

mining company’s obligations (if mining progresses) within the context of a

significant historical environmental condition.

Land use options

At the completion of the 1993-1998 monitoring period, four major land use options

exist for Rum Jungle:


1. The site remains as NT vacant crown land and access is restricted via the

Restricted Use Area declaration under the Soil Conservation and Land

Utilisation Act. In this scenario, issues detailed in Chapter 8 including weeds,

erosion, site access, wildfire and feral animals must continue to be managed.

The level and scope of monitoring various aspects of the rehabilitation should

be in accordance with recommendations made in the following chapters of

this report and as summarised in Chapter 1.

2. The Browns Project proceeds but operates only outside of Rum Jungle.

Management and monitoring issues on the Restricted Use Area would largely

remain the same, but may be influenced by adjacent mining operations and a

Beneficial Use declaration.

3. The Browns Project proceeds and extends into the rehabilitated area;

potentially encompassing the open cut pits and parts of the overburden

heaps. Dysons Open Cut and Overburden Heap would remain as potential

pollutant sources, irrespective of what happens to Whites and Intermediate

Overburden Heaps and Opencuts. Mining legislation and a Beneficial Use

declaration would drive environmental controls and monitoring.

4. The site is transferred to a Land Trust under the Finniss River Land Claim.

Should this situation arise, it must be recognised that the site remains

contaminated and options for traditional use will be limited. Management

responsibilities would transfer to the new owners and monitoring issues would

remain as per Option 1 above, if mining does not proceed as per Options 2 or

3.

2.5. CONCLUSION AND SUGGESTIONS FOR FURTHER WORK

Mining at Rum Jungle led to environmental impacts, which were significantly reduced

by a multi-million dollar rehabilitation program undertaken in the early 1980’s.

Monitoring since that time has demonstrated the success of rehabilitation as

measured against the original objectives set in 1982.


Given improved understanding of AMD and increased environmental standards and

expectations there has been a tendency to measure success against more

contemporary standards. Regardless of any amount of public investment, however,

Rum Jungle will remain a contaminated site. Environmentally or socially acceptable

limits to the amount of contamination emanating from the site will to some extent

change with time and context. The extent to which public investment can respond to

such changes in expectations needs to be clearly defined and appropriately justified

against well considered options for the site’s final land use, as does the level and

scope of any future management and monitoring.

Land use options for the Rum Jungle rehabilitation site currently include:

• A continuation of its current status as Crown Land under a Restricted Use Area

declaration;

• Mining of Browns deposit adjacent to and possibly within Rum Jungle; and/or

• Transfer of the site to Traditional Owners under the Finniss River Land Claim.

The Rum Jungle Monitoring Committee recommends that in the absence of any

change in land tenure, ongoing management of the site is in accordance with

responsibilities for managing vacant crown land. Northern Territory legislation and

the Restricted Use Area provision of the Soil Conservation and Land Utilisation Act

will continue to apply. The committee also understands that monitoring of water

quality at GS 8150097 will continue.

While some of the rehabilitation standards continue to be relevant, others are no

longer considered appropriate, or are at odds with the primary treatments used in

rehabilitation. The Rum Jungle Monitoring Committee recognises that recreational

use of the site is not possible and that given introduced pasture species were used in

rehabilitation, flora and fauna populations are not similar to those in adjacent areas.

In conducting monitoring at Rum Jungle, a large number of scientific questions

regarding biophysical processes operating at the site have emerged. Subsequent

chapters of this report suggest further work that could be undertaken to resolve

many of these issues. These suggestions, however, have no bearing on the


conclusion drawn from the formal monitoring period that rehabilitation has been

successful.

The Rum Jungle Monitoring Committee concludes that formal monitoring associated

with the Rum Jungle Rehabilitation Project is complete. It is recommended that as

the role of the Committee has now been fulfilled, its operation should cease on

publication of this report.


3. SURFACE WATER MONITORINGM D LAWTON

Department of Infrastructure, Planning and Environment, Darwin NT

R OVERALLEWL Sciences, Darwin NT

3.1. INTRODUCTION

The primary objectives of the monitoring program for the period 1993-98 and

outlined in 1994 by the Rum Jungle Rehabilitation Monitoring Committee were as

follows:

• To monitor and quantify the effectiveness of rehabilitation at the Rum Jungle

rehabilitated site in reducing pollutant loads from sources within the site and in

reducing the impact on the aquatic ecosystems within the Finniss River system;

• To investigate and make recommendations to the Commonwealth and NT

Governments regarding the long-term integrity of the rehabilitation works; and

• To investigate and make recommendations to the Commonwealth and NT

Governments regarding the usage of the site beyond the 1997-98 financial year.

This chapter is an interpretation of surface water data (hydrological and physico-

chemical) from the Rum Jungle monitoring program. Data is presented to illustrate

and quantify the effectiveness of the Rum Jungle Rehabilitation Project with respect

to the contamination of surface water in the East Branch of the Finniss River. To

achieve this objective, both historical data and data collected over the duration of the

1993-1998 project are displayed to demonstrate reduction in contaminant loads and

improvements in key water quality parameters.

It is considered relevant to the project objectives to give some extended description

to the overall surface water hydrology of the study area to illustrate the contaminant

transport conduits and their inter and intra-annual variability.


Gauge station network – data collection

Gauging station GS 8150097 (Plate 3.1) was used as the primary point for

monitoring of contaminate loads and flow in the East Branch of the Finniss River and

is located 5.6 km downstream from Rum Jungle. GS 8150200 is adjacent to the main

entrance of Rum Jungle and was fully instrumented in 1991 to monitor flow and

collect flow-weighted composite samples up to and including 1997-98. This station

was established to address an early concern that pollutants were ‘dropping out’

along an extended reach of the river. A later concern/hypothesis (Kraatz 1998) was

that contaminated groundwater discharged to the East Finniss downstream of Rum

Jungle (and GS 8150200) and that this was a possible contaminant conduit that

should be examined within the terms of the project brief. It was anticipated that

monitoring data from each of the stations would help answer these concerns.

Plate 3.1 Gauging station GS 8150097

Gauging station GS 8150097 was used as the primary point for monitoring of contaminantloads and flow in the East Branch of the Finniss River. The photo on the top left depicts thegauging station tower, while the bottom left shows the datalogger. In the top right photo is


the v-notch weir, which is the control point for the gauging station, while the bottom rightshows the automatic sampler for collecting water samples for water quality analysis.The overall program of water quality monitoring at the Rum Jungle site and East

Finniss River (physico-chemical and hydrology) undertaken over 1993-1998 relative

to the program of work reported in the 1988-93 Monitoring Report (1998 Kraatz)

included:

• The establishment of two gauging stations to continuously monitor inflow and

outflow for the open cuts – gauge stations GS 8150213 and GS 8150212

respectively. Data collected here was to consolidate understanding that the open

cuts contributed a significant proportion of the overall pollution load from the site;

• Establishment for the 1997/1998 wet season of a gauging station (GS 8150215)

to monitor run-off from the surface of Dysons open cut landform. This was

undertaken to provide data on the integrity of the cover following vegetation

dieback on the upper slopes;

• Re-opening in 1994/1995 of GS 8150204, situated several kilometres

downstream of the confluence of the Finniss River with its East Branch, to

monitor flow and collect daily water samples in association with extensive

concurrent biological surveys undertaken by ANSTO; and

• Continuation of a late-wet/early-dry season survey, begun in 1993, along a reach

of the East Finniss to ascertain whether there was contamination input

downstream of Rum Jungle via a groundwater conduit. This survey was

undertaken in 1994 and 1995.

In summary, for the period 1993-1998 that this report covers, continuous

hydrographic measurements and water quality data were collected and are available

as follows:

• 1993/1994 daily composite samples collected at GS 8150097 with metal suite *,

pH, conductivity; flow weighted composite (FWC) samples from GS 8150097,

GS 8150200, GS 8150212 and GS 8150213 with metal suite, pH and

conductivity.

• 1994/1995 daily composite samples collected at GS 8150097 and GS 8150204

with metal suite, pH and conductivity; FWC samples from GS 8150097,


GS 8150200, GS 8150212 and GS 8150213 with metal suite, pH and

conductivity.

• 1995/1996 FWC samples from GS 8150097, GS 8150200, GS 8150212 and

GS 8150213 with metal suite, pH and conductivity.





* Metal suite includes copper, zinc, manganese, iron (total and filtrable), calcium and magnesium.

3.2. METHODS

Hydrological data

Gauging station GS 8150097 was initially equipped in 1965 and has operated as a

continuous recording station for much of the time since. The gauging station control

is a shallow concrete v-notch weir downstream of the recorder (Plate 3.1). The

catchment area is 71 km2.

A second station was initially installed upstream at GS 8150200 in December 1981

and operated to August 1988. The station was re-opened in November 1991 for the

collection of hydrographic and water quality data and remained open until 1998. The

control structure is a gravel bar at the site of an old road crossing, a short distance

downstream of the tower. The cease to flow level has varied from a datum of 1.477

m (1981) to 1.436 m (1987) and 1.402 m (1993). The catchment area of 52 km2

includes the majority of the Rum Jungle rehabilitated site (in total ~ 0.6 km2). Run-off

from the rehabilitated tailings area discharges downstream of this station through Old

Tailings Creek (Figure 3.23).

The two gauging stations GS 8150097 and GS 8150200 had instrumentation

installed each consisting of a stilling well, float tape, shaft encoder, data logger and

automatic sampler(s). The stilling wells are of concrete pipe construction and are

connected to the river via 70mm galvanised pipes, placed at different levels to avoid

loss of data quality due to silt blockages. The dataloggers (SDS 'Torrens' - Adelaide)


were programmed and interrogated via laptop computer. Stage height data was

collected by programming the logger to 'wake up' every 5 minutes to read the shaft

encoder - if the reading changed from the preset 5 mm range of the previous reading

then the stage height and time was logged onto the data storage module.

Daily 500 ml composite samples were collected using a Sigma auto-sampler with a

24-bottle carousel and comprised three individual aliquots taken at eight hourly

intervals. Flow weighted composites were collected from an 80 L plastic container

that received pumped 500 ml aliquots from the river at intervals determined by river

flow. This process was achieved by programming the stage/discharge relationship

into the logger and having the logger, in 'wake up' mode, calculate the total volume

of water that had passed the station since the previous reading. Once the preset

volume of water was calculated to have passed, the logger sent a contact closure

signal to the sampler which pumped the designated aliquot and the logger then

wrote the time, date, sequential number, stage, flow and cumulative volume to the

data storage module.

Gauge stations GS 8150213 and GS 8150212 were set up in 1993/1994 as

continuously operated stations to monitor flow and water quality at the entry and exit

points of the open cuts. The set-up of each station represented something of a

challenge for agency hydrographic staff as flow at each site was subject to head

differentials as water levels in Whites and Intermediate varied over the wet season.

Site GS 8150213 also presented the problem that stage height recording was

undertaken at the inflow control weir 1 (see Plate 3.2 and Figure 3.2) but initial site

investigations revealed that mixing between flow from Fitch Creek and the upper

East Finniss was incomplete at this point. The sample collection point was located at

the entry culvert to Whites where mixing of inflow water was considered complete.

This necessitated some 500 m of communication cable to be laid between the stage

height recorder and the water sample pump and collection bin. This length of

exposed cable was subject to considerable environmental stress from fire, feral

animals and lightning strike and led to frequent loss of information and a

corresponding high maintenance effort.


GS 8150212 required accurate water level measurements to be recorded for the

Intermediate water body as discharge through the submerged exit culvert (see

Drawing W85-4049 Final Project Report Allen and Verhoeven 1986) was controlled

by the pressure head from the overlying water column. An ultrasonic transponder

unit was installed over the exit channel (see Plate 3.2) to measure water levels in the

open cut and the logger/sampler unit installed adjacent to the outflow culvert.

Chemical analysis

For the flow weighted composite samples, the bulk container was sub-sampled at

approximately weekly intervals with two 1 L representative samples being taken after

thorough mixing of the water and sediment (for an error estimation analysis of this

procedure please note section 3.4). Agency hydrographic staff provided this service

and samples were returned to the Government Water Laboratory in Darwin for

chemical analysis.

Hydrological data are presented as mean daily discharges (m3/s) in the case of daily

composite samples or, in the case of flow-weighted composite samples, in mega-

litres (ML) for the period that sub-samples were taken for the overall composite. All

hydrological data is stored in the agency corporate database HYDSYS®.

The laboratory treatment and analysis of the collected samples employed the same

protocol as reported previously (Kraatz 1998). That, in brief, included filtration of

individual sample aliquots through a 0.45 µm membrane to yield a sample for

analysis of the 'filtrable' heavy metal fraction and acidification of a separate aliquot to

allow for analysis of the 'total' heavy metal content.

3.3. RESULTS AND DISCUSSION

Hydrology of early and late flows at gauge stations GS 8150200 and GS8150097

Flow in the East Branch of the Finniss River is highly variable during the period

November-December, base-flow generally not being established until sustained


monsoonal rains arrive in January. Over this period, the immediate source of heavy

metals in the waters of the East Branch and Finniss River gradually changes. Initially

the remnant salts and evaporites left in the river bed and pools from the previous wet

season’s recessionary flow are re-mobilised with the first rain events of the season,

and this is followed by new contaminant inputs from the open cuts and seepage from

the Overburden Heaps.

Plots of early wet season flows at these two gauging stations (Figure 3.1) identify

that water at GS 8150097 begins to flow at a much later date than at GS 8150200

(up to 1 month later for all 5 years of this study).

Figure 3.1 Early wet season hydrology at GS8150200 and GS8150097 (1997-98)

The length of river between the two gauging stations is about 5.6 km. The delay in

the onset of flow recorded at GS 8150097 relative to GS 8150200 is due to a

combination of early wet season ‘patchy’ rainfall patterns over the catchment and the

time taken to ‘wet up’ the mainly dry river bed. There can be flows of up to 100 L/s at

GS 8150200 in the first weeks of the wet season prior to registration of flow further

downstream.

date (1997-98)December January February

flow

(m3 /s

) - lo

g

0.001

0.01

0.1

1

10

100

GS8150097GS8150200


Comparison of hydrological data at GS 8150200 and GS 8150212

Total flow estimated at GS 8150200 is an aggregate of that recorded at GS 8150212

(outflow from the open cuts), Wandering Creek input and the upper East Branch that

diverts via the Diversion Channel (Figure 3.2). Each season, base flow at

GS 8150200 is established up to 2 months earlier than outflow from the open cuts at

GS 8150212. The hydrological design incorporated into the rehabilitation works is

such that early flows from the upper East Branch flush through the Diversion

Channel for some time before beginning to flow into and fill the open cuts.

Correspondingly, flow ceases at GS 8150212 from 1.5 to 3 months earlier than at

GS 8150200 as low recessional flows are restricted to the Diversion Channel.

Figure 3.3 illustrates this flow pattern for 1993-1994 and Figure 3.4 shows the

pattern in 1997-1998. This hydrological pattern is significant because it demonstrates

that contaminants sourced from within the open cuts are generally only discharged to

the East Branch after base-flow in the river is established.

Figure 3.2 The diversion channel and weirs built on the East Finniss River to control riverflow


Figure 3.3 Comparative hydrology GS 8150200 and GS 8150212 (1993/94)


wet season hydrology 1997/98

Dec Jan Feb Mar Apr May

flow

(m3 /s

)

0.01

0.1

1

10

100

GS 8150200GS 8150212

Wet season hydrology 1993-94

Nov Dec Jan Feb Mar Apr May Jun

mea

n da

ily fl

ow (m

3 /s)

0.001

0.01

0.1

1

10

100

GS8150200GS8150212



Open cut gauge stations GS 8150213 and GS 8150212

Data was collected at gauge stations established at the inflow and outflow from the

open cuts (see Plate 3.2). This was conducted to collect supporting evidence that the

open cuts were a significant source of contamination and followed from previous

work (reported in Kraatz 1998) that examined the profiles of both water bodies over

an annual cycle for evidence of contaminant transport.

Once flow into the open cuts commences (as recorded at GS 8150213), the

evaporative draw down that occurs each dry season is replenished sequentially for

Whites, then Intermediate Open Cut. Once the deficit volume is replaced by fresh

inflow, overflow from the open cuts occurs and flow is registered at GS 8150212

(outlet from Intermediate Open Cut). The time elapsed between inflow to the Open

Cuts (GS 8150213) and the onset of outflow (GS 8150212) varied from a few weeks

to a month (see Figure 3.5 for 1997/1998 data).

date (1997-98)January February March April May

flow

(m3 /s

) - lo

g sc

ale

0.1

1

10

GS8150212GS8150213


Plate 3.2 The inflow (left) and outflow (right) gauge station set-ups at the open cuts withlevel recorders (top) and sampling stations (bottom)

As might reasonably be expected, annual estimates of discharge at GS 8150212 are

less than those for GS 8150213. However, the difference in these estimates varied

considerably from year to year. There is an average drawdown of ~1.5 m in Whites

(from 60 to 58.5 m AHD) which represents ~140 ML of water. In Intermediate, an

average drawdown of ~1.8 m occurs (from 58.5 to 56.7 m AHD), representing ~60

ML of water. As a check, an annual difference of ~200 ML between GS 8150212 and

GS 8150213 is therefore expected (or approximately 1.4% of mean total annual flow

at GS 8150212). In the 5 wet seasons this report covers, variations from this figure

give some indication of the gauging error at these sites. A difference of ~1% to 27%

(22.3, 27.4, 3.1, 5.7 and 1.1%) between total annual discharge at the two gauging

stations was recorded (with allowance for the 200 ML difference). The 1993/1994

and 1994/1995 estimates account for the greater discrepancies of 22.3% and 27.4%

respectively. As the new gauge stations were bought into service and fine-tuned in

terms of rating curves and integrity of data recording, improved agreement in terms

of water balance was achieved between the stations over the last 3 years of the

study.


The quality of water discharged from the open cuts (as monitored at GS 8150212)

was higher in solutes and lower in pH in comparison with water monitored at the

inflow (GS 8150213). This is reflected in Figure 3.6 where higher copper loads

relative to the inflow were consistently recorded at the outflow station.

Figure 3.6 Copper loads (in kg) as estimated at GS 8150213, 8150212, 8150200 and 8150097from 1993/1994 to 1997/1998

Annual Contaminant Loads

Hydrological data and annual contaminant load estimates calculated from water

quality data collected at GS 8150097 from 1969 to the present are presented in

Table 3.1. The East Branch of the Finniss River has a highly variable annual

discharge and is subject to large flow variations over any given wet season.

Continuous flow occurs only during the wet season and there is no flow at all for

most years from May through October.

0

2000

4000

6000

8000

10000

12000

14000

8150213 8150212 8150200 8150097

Ann

ual c

oppe

r loa

d (k

g)

1993-94

1994-95

1995-96

1996-97

1997-98


Table 3.1 Historical load data (in t) of selected pollutants sourced from the Rum Junglerehabilitated site as measured at gauging station GS 81500971.

Year Flow vol.(m3x106)

Rainfallmm

copper(total)

copper(dissolved)

zinc(total)

zinc(dissolved)

Manganese(total)

manganese(dissolved)

sulfate

1969/70 7 896 44 N/a 46 3300

1970/71 33 1611 77 24 110 12000

1971/72 31 1542 77 24 84 6600

1972/73 22 1545 67 22 77 5500

1973/74 69 2000 106 30 87 13000

1982/83 9.5 1121 23 5 6 1520

1983/84 48 1704 28 9 21 3600

1984/85 11.7 1136 9.1 4.1 7.2 1600

1985/86 11.4 1185 3.7 2.7 8.2 4400

1986/87 13.2 1222 5.6 2.7 8.6 2870

1987/88 6.3 1064 3.2 2 5.4 1230

1988/89 35 1600 5.4 4.4 19.2 3940

1989/90 3.1 900 1.8 1.6 3.9 760

1990/91 40.5 1590 14.9 3 7.4 6 30.5 24.1 4000

1991/92 7.1 1002 3.8 2.8 2.7 2.6 9.1 8.9 1260

1992/93 29.9 1421 11.9 5 3.9 3.9 24.7 21.8 2696

1993/94 26.1 1367 12.7 4.6 5.3 4.4 17.9 16.9 2281

1994/95 33.3 1580 10.6 4.5 5.8 5.0 18.9 17.6 2994

1995/96 9.0 996 2.9 1.7 3.0 2.5 8.7 8.1 1352

1996/97 77.9 1716 11.0 5.5 7.4 6.1 25.4 20.1 4357

1997/98 47.3 1688 12.4 4.3 6.8 5.8 28.4 24.9 4812

1998/993 53.2 1888 8.2 1.4 5.5 3.8 13.9 9.3 3682

1999/003 45.1 1712 8.9 1.0 4.5 0.8 15.0 6.2 3010

2000/013 64.6 1911 12.3 1.9 6.3 3.4 20.1 5.3 3925

Metal loads are calculated from analyses of acidified (total) and unacidified2 (dissolved)samples. Annual flow (as measured at GS 8150097) and rainfall (from R 8150205) data arealso included.

1 Data sourced (in part) from Davy Report (1975) and annual PAWA/WRD surface water monitoringreports 1983-1991 and 1988-1993 Monitoring Report (Kraatz 1998)2 From 1983/84 to and including the 1989-1990 wet season, water samples were analysed unacidified– prior to rehabilitation, acidity at GS 8150097 was such as to maintain the bulk of contaminants insolution.3 Results from 1998/1999 to 2000-2001 are included in Table 3.1 as data was available at time ofpublication – there is no further discussion of these results in this report.


One of the key objectives of the Rum Jungle rehabilitation project was a quantifiable

reduction in annual metal loads as monitored at GS 8150097. The objectives set

were for a 70% reduction in both copper and zinc and a 56% reduction in

manganese loads released from Rum Jungle.

A best fit regression of copper load versus discharge for the pre-rehabilitation period

indicates a non-linear relationship of the contaminant load leaving Rum Jungle each

wet season and the annual discharge volume (Figure 3.7). Data from the interim

period 1983/1984 - 1989/1990 were confounded by rehabilitation activities during

1983-1986 and only ‘dissolved metals’ data being available for several years

thereafter. Copper loads from the post-rehabilitation period (1990-1998), particularly

when the annual discharge as measured at GS 8150097 exceeds 20 gigalitres,

appear to be independent of discharge (Figure 3.8) and of the order of 10 – 12 t of

copper.

Figure 3.7 Annual copper loads (t) versus annual discharged volume (106m3)

As measured at GS 8150097 on the East Branch of the Finniss River over the period 1969 to 1998.

0 10 20 30 40 50 60 70 800

20

40

60

80

100

Pre-rehabilitationPre-rehab regressionPost-rehabilitationPost-rehab regression

DISCHARGE (106m3)

CO

PPER

LO

AD

(TO

NN

ES)

73/74

71/72

72/73

82/83

92/93 90/91

96/9798/99

97/98

99/0088/89

94/9593/94

86/8789/90


Figure 3.8 Annual copper load (t) estimated at GS 8150097 from 1990-1991 to 1997-1998.

pH – a measure of the acid in acid mine drainage

pH measurement is used as a qualitative indicator of the impact of acid discharged

from Rum Jungle on the surface water quality. No separate computations were done

to quantify acid load in terms of sulfuric acid tonnage although annual sulfate loads

are recorded in Table 3.1. These tonnages give some indication of the overall

historical and on-going acid generation and transport on and from the site. The

region is fortunate to have extensive carbonate rock assemblages (dolomite and

magnesite) that have provided extensive acid buffering capacity to the groundwater

and surface waters in the vicinity of Rum Jungle, and this in turn has led to

significant attenuation of the potential impacts from acidic drainage waters.

Nevertheless, the historical (pre-rehabilitation) data indicates that the mainly

bicarbonate buffering capacity of the region’s water resources was regularly

overwhelmed by the quantity of acid generated from the waste rock dumps. Figures

3.9 and 3.10 are frequency histograms of pH records at GS 8150097 comparing the

pre-rehabilitation period (1967-1981) with the period from 1990-1995. From these

figures, it can be seen that the median value occurs at pH 4.2 for the pre-

rehabilitation period and pH 6.3 for the 5 years from 1990 to 1995. At a pH of 4.2, no

significant buffer capacity via residual bicarbonate alkalinity remains in the water -

metal contaminants that may be in the water at this pH tend to be in a highly bio-

Cop

per L

oad

(t)

92/93 97/9896/97

90/91

94/95

93/94

91/92

95/96

0 10 20 30 40 50 60 70 800

5

10

15

20

Annual Discharge (106 m3)


available form. A shift in pH to a median value of 6.3 represents a significant

improvement in the quality of the receiving water to nearer neutral levels, and thus

elevation in pH also provides an attenuation of the toxicity of the contained metal

contaminants.

Figure 3.9 Frequency histogram of the prevailing pH at GS 8150097 during the pre-rehabilitation period (1967-1981)

The variation in mean monthly pH readings from both pre- and post-rehabilitation are

summarised in Table 3.2. The pH mean during the early wet season months of pre-

rehabilitation was ≥ 1.1 pH units lower than for the corresponding month(s) in 1990-

1995. The difference in the pH mean between the pre- and post-rehabilitation

periods in the late wet season months is even more pronounced (>1.5 pH units).

0

5

10

15

20

25

30

35

<3.1 3.4 3.7 4.0 4.3 4.6 4.9 5.2 5.5 5.8 6.1 6.4 6.7 7.0 7.3 7.6 7.9 8.2 8.5

pH

freq

uenc

y

0102030405060708090100

% c

umul

ativ

e fr

eque

ncy

frequency

% cumulative frequency


Figure 3.10 Frequency histogram of the prevailing pH at GS 8150097 during the post-rehabilitation period (1990-1995)

Table 3.2 Statistical data of pH measured at GS 8150097 during pre- and post-rehabilitationperiods classified according to the month of sampling

Month: December January February March April May-June

Pre-rehabilitation period (1968-1985)

mean 4.19 4.17 4.29 4.66 5.14 4.84

std dev 0.16 0.40 0.45 0.45 0.80 0.66

max 4.60 5.90 5.40 6.60 6.80 6.40

Min 3.60 3.08 3.10 3.30 3.25 3.10

n 64 123 71 106 67 57

Post-rehabilitation (1990-1995)

mean 5.08 5.47 5.76 6.40 6.51 6.63

std dev 0.62 0.71 0.74 0.47 0.48 0.61

max 6.60 6.9 6.93 7.10 7.10 8.34

Min 4.38 4.18 4.60 5.10 4.50 4.70

n 53 109 121 136 119 135

0

10

20

30

40

50

60

70

80

<3.1 3.4 3.7 4 4.3 4.6 4.9 5.2 5.5 5.8 6.1 6.4 6.7 7 7.3 7.6 7.9 8.2 >8.5

pH

freq

uenc

y

0

20

40

60

80

100

cum

ulat

ive

%

frequency

cumulative %


Figure 3.11 Mean pH values of water samples collected at GS 8150097 during pre-rehabilitation (1968-1985) and post-rehabilitation (1990-1995) periods classifiedby month of sampling.

Frequency distribution of metal concentrations recorded at GS 8150097

Copper

As discussed in the 1988/1993 Monitoring Report (Kraatz 1998), a presentation of

cumulative frequency histograms of metal concentrations monitored at GS 8150097

before (1968-1981) and after rehabilitation (1990-1995) was recommended as a

potentially helpful illustration of water quality improvements associated with the site

rehabilitation. The pre-rehabilitation median copper concentration at GS 8150097

was ~7 mg/L, post-rehabilitation <0.5 mg/L (Figures 3.12 and 3.13). The difference

between the two median concentration values represents a significant improvement

in water quality with respect to copper concentration and perhaps a more meaningful

performance indicator of the effectiveness of the rehabilitation than overall load

measurements. The reduction in median copper concentrations, is approximately

one order of magnitude or ~95% and the rehabilitation objective was for a 70%

reduction in ‘load’. Almost 90% of water samples collected during the period 1990-

1995 had a copper concentration <1 mg/L. This contrasts significantly with results

exhibited in Figure 3.12 where a substantial number of samples (~24% of all

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Dec Jan Feb March April May-June

Month

pH pre-rehabilitationpost-rehabilitation


samples analysed) registered a copper concentration of >28.5 mg/L, 30% of samples

collected contained ≤1.5 mg/L of copper and only 18% of samples had <1.0 mg/L.

Figure 3.12 Frequency and cumulative percent frequency histogram of copper concentrationvalues (mg/L) at GS 8150097 during the pre-rehabilitation period (1968-1981)

Figure 3.13 Frequency and cumulative percent frequency histogram of copper concentrationvalues (mg/L) at GS 8150097 during the period 1990-1995

0

5

10

15

20

25

30

35

40

45

50

0.5 2.5 4.5 6.5 8.5 10.5

12.5

14.5

16.5

18.5

20.5

22.5

24.5

26.5

28.5

Cu concentration (mg/L)

freq

uenc

y

0

10

20

30

40

50

60

70

80

90

100

cum

ulat

ive

%

frequency

cumulative %

0

50

100

150

200

250

300

350

400

450

0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 15

.5 17 18.5 20 21

.5 23 24.5 26 27

.5 29

total Cu (mg/L)

freq

uenc

y

0

20

40

60

80

100

cum

ulat

ive

%

frequency

cumulative %


Table 3.3 Statistical analyses of copper concentrations of water samples from GS 8150097based on the month of collection and comparing pre- and post-rehabilitation data

Month: Dec Jan Feb Mar April May June

Pre-rehabilitation period 1968-1985

mean 34.1 29.4 5.6 1.6 1.5 2.5 2.6std dev 32.9 44.1 9.3 2.0 5.2 2.9 0.8

max 122 182 48 12 42 21 4Min 0.1 0.2 0.1 0.1 0.1 0.3 1.7n = 67 116 70 101 64 53 4

Post-rehabilitation period 1990-1995

mean 1.08 0.61 0.76 0.60 0.37 0.33 0.14std dev 0.56 0.46 0.52 0.74 0.39 0.19 0.07

max 2.48 2.48 3.07 5.18 2.51 1.19 0.28Min 0.12 0.08 0.16 0.01 0.05 0.06 0.04n = 53 109 121 136 119 105 30

0

10

20

30

40

50

60

70

80

Dec Jan Feb Mar April May June

Month

copp

er (m

g/L)

1968-19851990-1995

Figure 3.14 Mean monthly copper concentrations (total in mg/L) of water samples collectedat GS 8150097 during two separate periods: 1968-1985 and 1990-1995


0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Dec Jan Feb Mar April May June

Month

Cu

(mg/

L)

1990-1995

Figure 3.15 Mean monthly copper concentrations (total in mg/L) of water samples collecteddaily at GS 8150097 from December 1990 to June 1995.

Error bars represent standard deviations

Figure 3.14 demonstrates the difference between the mean copper concentrations in

water samples collected from GS 8150097 during pre- and post-rehabilitation

periods on a month by month basis. In contrast with those of the pre-rehabilitation

period, the post-rehabilitation values are so much lower on the scales used for

Figure 3.14 that, for the sake of clarity, these values have been plotted separately in

Figure 3.15.

The highest mean copper concentrations were recorded for the month of December,

both pre- and post-rehabilitation, with a mean value of ~1 mg/L for the 1990-1995

period. Post-rehabilitation, the mean copper concentration was ~ 38 mg/L for 1968-

1981 and over succeeding months was <1 mg/L and dropped gradually as flushing

and dilution processes took place (Figure 3.15).


Zinc

Cumulative frequency histograms of zinc concentrations of water sampled at

GS 8150097 during pre-rehabilitation (1968-1981) and the more recent period of

1990-1995 are shown in Figures 3.16 and 3.17 respectively. The median zinc

concentration (total) for the post-rehabilitation period is ~0.3 mg/L. This is in contrast

with the median concentration of ~1.5 mg/L for the pre-rehabilitation period. This can

be interpreted as an improvement of some 80% in zinc loading to the system, thus

achieving the rehabilitation objective of a 70% reduction in load.

Figure 3.16 Frequency and cumulative frequency histogram of zinc concentration (mg/L) asmeasured at GS 8150097 during the pre-rehabilitation period (1968-1981)

0

2

4

6

8

10

12

0.05 0.2

0.35 0.5

0.65 0.8

0.95 1.1

1.25 1.4

1.55 1.7

1.85 2

2.15 2.3

2.45 2.6

2.75 2.9

3.05 3.2

3.35 3.5

3.65 3.8

total Zn mg/L

Freq

uenc

y

0

0.2

0.4

0.6

0.8

1

cum

ulat

ive

fract

ion

FrequencyCumulative %


Figure 3.17 Frequency and cumulative percent frequency histogram of zinc concentration(mg/L) as measured at GS 8150097 during the post-rehabilitation period (1990-1995)

Manganese

Cumulative frequency histograms of manganese concentrations in water sampled at

GS 8150097 during pre-rehabilitation (1968-1981) and the more recent period of

1990-1995 are shown in Figures 3.18 and 3.19 respectively. The median

manganese concentration (total) for the post-rehabilitation period is ~0.9 mg/L. This

is in contrast with the median concentration of ~3 mg/L for the pre-rehabilitation

period and can be interpreted as a 70% improvement in manganese load. The

rehabilitation objective was for an improvement of 56% post-rehabilitation.

Furthermore, all manganese concentrations measured at GS 8150097 during 1990-

1995 were ≤ 3.6 mg/L.

0

20

40

60

80

100

120

0.05 0.3 0.5

5 0.8 1.05 1.3 1.5

5 1.8 2.05 2.3 2.5

5 2.8 3.05 3.3 3.5

5 3.8

total Zn (mg/L)

freq

uenc

y

0

20

40

60

80

100

cum

ulat

ive

%

frequency

cumulative %


Figure 3.18 Frequency and cumulative percent frequency histogram of manganeseconcentration (mg/L) as measured at GS 8150097 during the pre-rehabilitationperiod (1968-1981)

Figure 3.19 Frequency and cumulative percent frequency histogram of manganeseconcentration (mg/L) as measured at GS 8150097 during the post-rehabilitationperiod (1990-1995)

0

50

100

150

200

250

300

350

0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 15

.5 17 18.5 20 21

.5 23 24.5 26 27

.5 29

total manganese (mg/L)

freq

uenc

y

0

20

40

60

80

100

cum

ulat

ive

%

frequency

cumulative %

05

101520253035404550

0.5 2.5 4.5 6.5 8.5 10.5

12.5

14.5

16.5

18.5

20.5

22.5

24.5

26.5

28.5

30.5

32.5

total manganese (mg/L)

freq

uenc

y

0

20

40

60

80

100

cum

ulat

ive

%

frequencycumulative %


Contaminant loads – delivery schedules to the receiving environment

It is instructive to examine the scheduling of copper contamination export from Rum

Jungle to the East Branch of the Finniss River. Figure 3.20 plots data collected at the

two gauge stations near the outflows from Rum Jungle. Gauge station GS 8150200

was located so as to gauge flow and collect load data in the East Branch proper,

whereas GS 8150212 was positioned at the open cut outflow, a short distance (200

m) upstream of GS 8150200. Contaminant discharge from the open cuts occurred

mainly over the period of high flow, as discussed in section 3.3. The open cuts take

time to be replenished and both the early flows and then late recessional flows are

directed down the diversion channel (see Figure 3.2).

Figure 3.20 Cumulative flow and cumulative copper load at GS 8150200 and 8150212 over wetseason 1997/1998.

For wet season 1997-1998 the cumulative plots (Figure 3.20) indicate that for GS

8150212 ~90% of the load (2.8 t copper) sourced from the open cut area was

delivered from the open cuts to the river by early March 1998. The total load

recorded at GS 8150200 for the 1997-1998 wet season was 10.9 tonne copper –

however, by March 1998 only 5.5 tonne copper had been recorded at the station

December January February March April May June

cum

ulat

ive

flow

(ML)

0

5000

10000

15000

20000

25000

30000

35000

cum

ulat

ive

copp

er lo

ad (k

g)

0

2000

4000

6000

8000

10000

12000

cumulative flow (GS 8150200)cumulative copper (GS8150200)cumulative flow (GS 8150212)cumulative copper (GS 8150212)


(or ~50% of the total load). At this time, approximately 50% of the 5.5 tonne load can

be attributable to copper sourced from the open cut discharge, notwithstanding that

~85% of the total flow for the wet season had already passed the station.

That is to say, the remaining 50% of the copper load recorded at GS 8150200 for

wet season 1997/1998 was associated with the recessional flow (~15% of the total

flow). It can be deduced that, since inflow to the open cuts had more or less abated

by this time (and hence upper catchment flow upstream of Rum Jungle), the bulk of

the copper load was sourced from the general area of the diversion channel adjacent

to the waste rock dumps.

A similar bias of load carried during the lower flow periods can be seen at the onset

of wet season 1997-1998. The first 10% of flow at GS 8150200 accounts for 18% of

the annual copper load as estimated at this site. However, only 0.4 t of the copper

load (from a cumulative amount at GS 8150200 of 1.9 t or ~20%) can be attributed to

open cut outflow at this time (Jan 19th 1998).

This assessment suggests that the principal mechanism through which elevated

copper concentrations are generated in the East Branch (and by inference biological

detriment to the river ecology) can be attributed to early and late wet season

discharges from the vicinity of the waste rock dumps into low flows in the main

channel.

Figure 3.21 further illustrates this process by plotting the ‘spot load’ estimates for

each station in tandem with the cumulative plots also displayed in Figure 3.20. It is

clear from these plots that load ‘delivery’ from the open cuts is strongly biased to

mid-wet season discharge whereas the load monitored at GS 8150200 is almost bi-

modal with bias at the early and late periods of the wet season.


Figure 3.21 Cumulative and spot copper loads at GS 8150200 and GS 8150212 over wetseason 1997-1998

Finniss River downstream of the confluence with its East Branch (GS 8150204)

GS 8150204 is situated downstream of the confluence of the Finniss River with its

East Branch (Figure 3.23). The gauging station was used to monitor flow and collect

daily water samples during the 1988/1989 and 1994/1995 wet seasons.

In most years and at most times there is a large dilution factor for any contaminants

as they enter the Finniss River from the East Branch. This is clearly demonstrated in

Figure 3.22 where mean monthly copper concentrations at GS 8150204 are much

reduced in relation to those at GS 8150097. Dilution of copper from GS 8150097 to

GS 8150204 was variable, even during periods when flow had become continuous in

each waterway. This is due to the seasonal variability in rainfall and runoff over the

respective catchments.

Date (month)

Jan Feb Mar Apr May Jun

copp

er lo

ad (k

gs)

0

200

400

600

800

1000

1200

1400

1600

cum

ulat

ive

load

(fra

ctio

n)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.0

1.0

spot loads GS 8150200spot loads GS 8150212cumulative load GS 8150212cumulative load GS 8150200


0.0

0.5

1.0

1.5

2.0

2.5

3.0

Dec Jan Feb March April May June

Month (1994/1995)

copp

er c

once

ntra

tion

(mg/

L)

GS8150204GS8150097

Figure 3.22 Average monthly copper concentrations (mg/L) at GS 8150097 and GS 81500204during the 1994/1995 wet season (error bars indicate standard deviations)

The contaminant load estimates at GS 8150097 and downstream at GS 8150204

during 1987/1988 and 1994/1995 are summarised in Table 3.4.

Table 3.4 Comparison of pollutant loads (t) estimated at GS 8150097 and GS 8150204 in wetseasons 1987/1988 and 1994/1995

Flow

m3 x 106 Copper Manganese Zinc Sulfate

GS 8150097 6.3 3.2(dissolved)

5.4(dissolved)

2.0(dissolved) 1260

1987-19881

GS 8150204 55 3.2 1.5 2.0 1300

GS 8150097 33.3 10.6 (total) 18.9 (total) 5.8 (total) 29941994-19952

GS 8150204 316.9 16.7 (total) 24.9 (total) 9.5 (total) 5098

1 After C.H.R.F. Henkel “East Finniss River and Finniss River Pollution Study 1987-1988” PAWA2 For the wet season period 13/12/94 to 13/06/95


The discrepancy in estimated total copper loads (>50%) between the two stations for

1994/1995 is considerable and mainly serves to illustrate the difficulties and

shortcomings in data collection using different techniques, each with their inherent

inaccuracies. Load estimates at GS 8150204 were calculated from low level

concentration data generated by flame AAS (with a relatively high detection limit of

0.01 mg/L) and multiplied by large volumetric factors – this combination leads to

significant magnification of errors in load estimates. The estimate from GS 8150097

used flow-weighted composite samples with higher contaminant concentrations -

error magnification is minimised with this approach and the 10.6 tonne load estimate

for copper should be considered the more accurate of the two estimates.

Table 3.5 Change in water quality at GS 8150204 with respect to copper concentration(mg/L) between the 1987/1988 and 1994/1995 wet seasons

Wet season 1987/1988 1994/1995

Mean copper concentration (mg/L) 0.23 0.04

Standard deviation 0.18 0.03

Maximum copper concentration (mg/L) 1.14 0.16

The ratio of the catchment areas of the two gauging stations GS 8150204 and

GS 8150097 is ~7:1 (GS 8150204 is 483 km2, GS 8150097 is 71 km2). Therefore a

seven-fold increase in total flow and corresponding decrease in contaminant

concentrations is expected when comparing GS 8150204 with GS 8150097,

assuming negligible contributions to contaminant concentrations from inflow from the

upper Finniss River. Comparison in water quality at GS 8150204 with respect to

copper concentrations between the years 1994/1995 and 1987/1988 suggests a

significant improvement in water quality over this period. However, in comparison

with the overall flow in 1994/1995, flow during the 1987/1988 wet season was low.

Given that both monitoring periods were post-rehabilitation, this suggests that the

‘projection’ of the contaminant influence from Rum Jungle to the wider receiving

environment (eg the main Finniss River) will be influenced by the prevailing seasonal

hydrological regime.


Dysons open cut landform – run-off monitoring

There were some shortcomings in the original 1983-1986 site rehabilitation works

that became obvious from post rehabilitation monitoring undertaken over the period

1986-1992. Following rehabilitation, concerns were raised about the contribution of

drainage from Dysons Overburden Heap and opencut landform to the overall off-site

contaminant load and the effectiveness of their respective covers. Data collected in

1986 indicated that the “integrity of the rehabilitation work may have been breached”

(Henkel, Pollution Study 1987/88). During the 1986/1987 wet season an estimated

2.3 ML of highly polluted water sourced from runoff from the cover and carrying 670

kg of copper and 1.4 x 106 Bq of Radium-226 found its way to the East Finniss River

system. This represented 12% of the total copper load as measured for that wet

season at GS 8150097. The landform was re-contoured in dry season 1987 and

water quality monitoring over 1987-1988 confirmed that the repair work was effective

and led to reduced copper and radium-226 contamination in the runoff in the

following wet season, although concentrations were still elevated (Table 3.6).

Table 3.6 Comparison of pollutant concentrations and loads at Dysons Open Cut landformdrain (GS 8150215) between 1986/1987, 1987/1988 and 1997/1998

Year(rainfall)

Copper Radium-226

max(mg/L)

Min(mg/L)

mean(mg/L)

load(kg)

max(Bq/L)

Min(Bq/L)

mean(Bq/L)

load(Bqx106)

1986/87(1222mm)

780 110 290 670 0.74 0.59 0.62 1.4

1987/88(1064mm)

83 2 35 11 0.86 0.12 0.55 0.2

1997/98(1688mm)

11.0 2.5 5.4 95.3 - - - -

Further concerns were raised with the discovery of vegetation dieback on the upper

parts of the cover (see Chapter 5). Inspection of the dieback regions of the landform

revealed that the uppermost cover material (2A) was not to project specification. The

pH of the cover layers was highly acidic with only a marginal difference between the

pH of Rum Jungle tailings (pH 3.4) and cover layers (pH 3.8 - 4.2). A gauge station


(GS 8150215 - catchment area 0.041km2) was used in 1997/1998 to monitor run-off

from Dysons landform to assess both its contribution to overall site contamination

and to provide information relating to the rate of erosion of the cover. This work was

driven by concern that dieback of grass cover and subsequent increased

vulnerability to erosion at the upper end of the landform may have a medium to long-

term impact on the viability of the cover.

However, based on data presented in Table 3.6 the quality of the run-off water

appears to have improved, relative to the data collected 10 years earlier with respect

to concentration of copper. The issue of disparate rainfall regimes for each of the

study years confounds meaningful interpretation of the data. The water samples

collected at GS 8150215 in 1997/1998 had a mean pH of 4.8 (max. 5.7, min. 4.3 std.

dev. 0.5).

Additional data collected from GS 8150215 during the 1997/1998 wet season

(rainfall 1688 mm) indicated that runoff (total volume ~20 ML) had an average of 94

mg/L (max. 268 mg/L, min. 21 mg/L, std.dev. 61 mg/L) of total suspended solids

(TSS). This equates to approximately 1800 kg of cover material being eroded from

the landform of 0.041 km2 (or 440 kg/ha) over the 1997/1998 wet season. However,

no further data is available on suspended solids transport from this cover to inform

whether erosion is occurring at a rate that will sustain the cover integrity within

acceptable limits. Other studies undertaken in the region (Padovan, 2001) that

include sediment export coefficient determinations document the inter-annual

variability that can be attributed to variation in the rainfall regime and landuse

category but do not address other variables such as catchment geomorphology. For

the ‘rural’ and ‘undisturbed’ landuse categories monitored in those studies, sediment

export coefficients varied from ~50-300 kg/ha. The total suspended solids load

estimated at GS 8150097 during the 1993/1994 wet season was 219 t (or ~31

kg/ha). A little more than 111 t of suspended solids (or ~20 kg/ha) passed

GS 8150200 during the 1993/1994 wet season or about half the total load that

passed GS 8150097 for the same period.


East Finniss River reach surveys

Longitudinal, river-reach profiles of the water chemistry along the East Branch of the

Finniss River were conducted in three consecutive years on 22/04/93, 22/04/94 and

15/06/95. This was done to assess the contamination regime downstream of Rum

Jungle and included water, sediment and algal assays in 1993. Twenty-seven

sample sites (Figure 3.23) were selected in 1993 at intervals along the 5.6 km

stretch of the river between the two gauging stations - from GS 8150097 (site 1) to

GS 8150200 (site 27). The work undertaken in 1993 was previously reported (Kraatz

1998). In 1994 the sampling regime was extended to include another 12 sample

sites in the 2.6 km reach of the river downstream from GS 8150097 to the

confluence with the Finniss River.

An hypothesis outlined on p25 of the 1988-1993 Monitoring Report (Kraatz 1998)

suggested that additional calcium, magnesium, sulfate and manganese

concentrations in water at GS 8150097 might be attributable to contaminated

groundwater in-flow entering downstream of GS 8150200.

Examination of annual load data for the years 1993/1994 to 1997/1998 indicates that

additional calcium, magnesium (in 3 out of 5 years), sulfate (in 4 out of 5 years),

copper, manganese and nickel (4 out of 5 years) is seen at GS 8150097 relative to

GS 8150200 (eg Figure 3.6). Table 3.7 summarises the spot water quality and

instantaneous flow data taken at each station on each of the specified sampling

dates.


Table 3.7 Relative ratios in water flow, solute concentrations (mg/L) and conductivity(µScm-1) at GS 8150097 (site 1) and GS 8150200 (site 27) on specified days

Date Flow(m3/sec) Cu Zn Mn Ni Ca Mg SO4

= Fe Al EC25 pH

site 27(GS8150200) 0.001 3.65 7.75 7.2 3.85 78 239 922 19.3 - 2070 3.4

site 1(GS8150097) 0.022 0.56 0.87 1.5 0.56 34 74 401 0.18 - 786 6.8

22/04/93

ratio sites 27:1 0.1 6.5 8.9 4.8 6.9 2.3 3.2 2.3 107.2 - 2.6

site 27(GS8150200) 0.087 1.03 1.62 1.86 0.95 21 72 399 724 - 724 6

site 1(GS8150097) 0.104 0.51 0.73 0.95 0.44 27 59 285 591 - 591 6.5

22/04/94

ratio sites 27:1 0.8 2.0 2.2 2.0 2.2 0.8 1.2 1.4 128.7 - 1.2

site 27(GS8150200) 0.004 14.4 25 23 17.05 135 585 3330 15.3 64 4200 3.05

site 1(GS8150097) 0.001 0.15 0.31 0.94 0.22 24 48 270 0.07 0.18 557 6.48

15/06/95

ratio sites 27:1 4.0 96.0 80.6 24.5 77.5 5.6 12.2 12.3 218.6 355.6 7.5


Figure 3.23 Map of the sampling sites along the East Finniss River and the location of gauging stations GS8150097 and GS 8150200


1994 survey

Recessional flows at the two gauging stations over the period including the sampling

date (22/04/94) are plotted in Figure 3.24. These show that flow at GS 8150097 is

greater than at GS 8150200 until the end of April, when it decreased rapidly until

cease-to-flow on 9th May. In contrast, flow continued at GS 8150200 until the end of

June. Rainfall data for this period shows that intermittent rain fell at Rum Jungle on

most days up until the 9 May.

Figure 3.24Hydrology of late wet season flow at GS 8150097 and GS 8150200 in 1994

Late wet season recessional flows 1993/1994

March April May

flow

(m3 /s

)

0.001

0.01

0.1

1

10

100

GS 8150097GS 8150200

sample date 22/04/94


Figure 3.25 Water quality measures (including heavy metals) along the reach of the EastFinniss River as recorded on samples collected 22/04/94

In the survey of 22/04/94, water quality improved progressively downstream of Rum

Jungle and this improvement was similar to the trend documented for 1993. In 1994

however, rainfall was more frequent during the late wet season than in 1993, so

catchment run-off between the two stations contributed to significant dilution of river

water downstream of GS 8150200. On the sample date (22/04/94) about 20% more

water was flowing past site 1 than site 27. Figures 3.25 and 3.26 plot solute

concentrations, conductivity and pH vs distance downstream from Rum Jungle. The

plots demonstrate fluctuating, although gradually increasing pH with a concomitant

gradual decrease in heavy metal concentrations with increasing distance from Rum

Jungle. Calcium, magnesium and sulfate concentrations increased from GS 8150200

for about 1 km downstream. This indicates that within that reach of river there is an

inflow of water with high concentrations of these solutes. The sampling regime

undertaken in 1994 included 8 extra sampling sites over about 2.6 km downstream

of GS 8150097 to the confluence of the Finniss River. The quality of the water in this

reach of the river (between 5.6 and 8.3 km downstream of Rum Jungle) was

influenced by an inflow of lower TDS water (~5.8 km downstream of the site), but this

had no indication of contamination.

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.04.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

450

500

550

600

650

700

750

800

850

900

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

cond

uctiv

ity (u

S/cm

)

pH (p

H u

nits

)

met

al c

once

ntra

tion

(mg/

L)

conductivity

pH

nickel

zinc

manganese

copper

distance downstream of minesite


Figure 3.26 Water quality measures (including sulfate, calcium & magnesium) along thereach of the East Finniss River as recorded on samples collected 22/04/94

1995 survey

On the date that sampling was undertaken (15/06/1995), flow at GS8150097 was

<1L/s (Figure 3.27). From site 27 (GS 8150200) to site 1 (GS 8150097, 5.6 km

downstream from Rum Jungle) the quality of the East Finniss River water improved

markedly with respect to pH, increasing from pH 3.2 to 6.9. Figure 3.28

demonstrates a gradual improvement in pH as the distance from the former Rum

Jungle minesite increased. This survey was less comprehensive than the previous

two years and focussed on the reach of river immediately downstream of Rum

Jungle. Aluminium was included in the suite of parameters analysed – the presence

of extensive iron and aluminium chemical flocs downstream of the site was very

apparent (Plate 3.3). The concentration of aluminium dropped dramatically (64mg/L-

5mg/L) as the pH increased from 3.2 to 4.9 over the 750 m reach. Iron

concentrations decreased from 15mg/L to 0.1 mg/L over the same reach.

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.04.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

450

500

550

600

650

700

750

800

850

900

0

10

20

30

40

50

60

70

80

90

100

200

250

300

350

400

450

500

distance downstream from minesite (km)

sulfa

te c

once

ntra

tion

(mg/

L)

calc

ium

/mag

nesiu

m c

once

ntra

tion

(mg/

L)

cond

uctiv

ity (u

S/cm

)

pH (p

H u

nits

)

calcium

sulfate

magnesium

conductivity

pH


Rainfall data for this year indicates that although sporadic through until late May,

significant rainfall events had ceased some six weeks prior to when the sample run

was undertaken (15/06/95).

Plate 3.3 Iron and aluminium chemical flocs observed as surface scums in the EastFinniss River, approximately 700 metres downstream of Rum Jungle

This survey again supports the understanding from the previous years that

groundwater discharge to the river occurs between sites 25 and 23 (between 500

and 900 m downstream from Rum Jungle) and this groundwater has a beneficial

effect on the acidic leachate from Rum Jungle. However, at this later time, it appears

that the influence of this groundwater input is diminished.


It was the intention of the river surveys to establish whether any significant

contamination from Rum Jungle could be found being expressed via groundwater

discharge to the river downstream of Rum Jungle. This issue had arisen and was

considered worthy of further investigation when water quality data collected in 1993

was interpreted (Kraatz 1998) as potentially indicative of contaminant inflows

downstream of GS 8150200. The follow-up surveys of 1994 and 1995 have

confirmed that no such discharge is evident. Rather there is, apart from groundwater

inflow approximately 500-700m downstream of GS 8150200, a gradient of

diminishing contamination driven by a simple dilution mechanism as leachate from

Rum Jungle flows into the series of pools and riffles remaining after the flushing

flows of the wet season. The extent of this contamination is dependent on the

particular hydrological regime each year.

Figure 3.27 Late wet season (1995) hydrology at gauge stations GS 8150097 and GS 8150200

Late wet season hydrology 1994-1995

Mar Apr May Jun

flow

(m3 /s

)

0.01

0.1

1

10

100

GS 8150097GS 8150200

sam ple date 15/06/95


Figure 3.28 Variation in water quality measures in the East Branch of the Finniss River withdistance downstream from Rum Jungle on 15/06/95

3.4 WATER SAMPLING – ERROR ESTIMATIONS ON COMPOSITE SAMPLES

Given some significant inconsistencies in load estimates between gauge stations

that were recorded over the monitoring period, especially between GS 8150200 and

GS 8150097, an exercise was undertaken to look at some aspects of error and

inaccuracy in the collection of water samples and subsequent analysis of those

samples. This followed on from the river reach survey work that indicated that there

were no contaminant inflows to the East Finniss between the two stations. As

described earlier, the chemical analysis of flow-weighted samples was used as the

basis to estimate annual contaminant loads. These samples were collected at each

of the monitored stations by sub-sampling from bulk 80 L plastic containers.

Sub-sample collection from the gauge stations and dispatch of the samples to the

government water laboratory in Darwin for analysis was made periodically (generally

weekly). Two 1 L bottles were used to collect replicate samples during or

immediately following agitation of the accumulated bulk sample in the container. In

the laboratory, the procedure followed was for one of the two 1 L samples to be

analysed for the general parameters – that is pH, conductivity, sulfate, calcium and

magnesium. The other 1 L sample was partitioned into two sub-samples. One sub-

distance (km) downstream from minesite0 1 2 3 4 5 6

pH (p

H u

nits

)

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

cond

uctiv

ity (u

S/cm

)

500

1000

1500

2000

2500

3000

3500

4000

4500

sulfa

te (m

g/L)

500

1000

1500

2000

2500

3000

3500

calc

ium

& m

agne

sium

(mg/

L)

0

50

100

150

200

250

300

350

400

450

500

550

600

pHConductivity sulfatecalcium magnesium


sample was acidified to pH < 2 (0.5 mL HNO3 AR grade per litre of sample) before

being analysed for the heavy metal suite via flame atomic absorption spectrometry

(AAS). The other sub-sample was filtered (0.45µm) prior to AAS analysis for an

estimation of the filtrable heavy metal fraction.

Methodology

An estimate was made of the relative error involved in the field sub-sampling

component with respect to total heavy metals. The following methodology was

employed.

Fifteen individual 500 mL samples were collected from the 80 L sample storage bin

at GS 8150097 on the 23/03/99. The 500 mL sample bottles were immersed in the

bulk container following agitation/homogenisation of the composite sample. Samples

were transported back to the laboratory for preparation and analysis. In the

laboratory, samples were acidified as per standard protocol (0.5 mL HNO3/L sample)

inverted to mix and left to stand for a minimum of 24 hours. The 15 samples were

then analysed in triplicate by apportioning three 10 mL aliquots of the 500 mL bulk

sample. Analysis of the metals was undertaken by atomic absorption

spectrophotometry (Varian SpectAA 300/400). Statistical treatment of results

involved determination of the mean, range and standard deviation of the metal

concentrations both between analytical triplicates and between the fifteen field

replicates collected. The following is a discussion of the potential errors involved with

bulk composite sample collection and sub-sample analysis.

Results and discussion

Less than 0.5% relative standard deviations (RSD) in copper concentrations (avg.

0.27%) occurred between laboratory triplicates (Table 3.8). The calculated RSD

between copper determinations on each of the 15 field replicates, on the other hand,

was 9.7%. This can equate to an error in calculated annual copper loads of up to 1.2

t. Considering that there is also an estimated 10% error in the stage height and flow

rating tables used to estimate flow, the error in representative sub-sampling can be

further compounded as total load calculations are made. The results from the


laboratory analyses are presented in Figure 3.29 as the ‘normalised’ average result

for each of the 15 sub-samples.

This exercise demonstrates a clear issue with regard to inaccuracies introduced at

the point of collection of a representative sub-sample from the bulk sample in the

field. This has particular relevance when elevated concentrations of iron and

aluminium salts are present, as is the situation at Rum Jungle. These salts will be

subject to precipitation/settlement as the bulk pH of the sample increases and time

(up to a week) elapses. To re-homogenise the bulk sample in the field to allow for

improved representative samples to be taken presents a challenge. One possible

solution is to have the composite bin as a changeover unit for each site visit and to

only sub sample in a laboratory environment.

Table 3.8 Statistical results from field and laboratory replicates of sub-samples of GS8150097 composite sample collected on the 23/03/99

Cu (µµµµg/L) Fe (µµµµg/L) Mn (µµµµg/L) Ni (µµµµg/L) Zn (µµµµg/L)

Mean 217.7 546.8 411.8 101.4 106.4

std dev (lab reps) 0.6 3.3 1.1 4.0 0.2

RSD (%) (lab reps) 0.3 0.6 0.3 3.9 0.2

std dev (field reps) 21.0 52.7 14.3 3.1 7.7

RSD (%) (field reps) 9.7 9.6 3.5 3.1 7.2


Figure 3.29 Normalised metal concentrations from 15 individual sub-samples collected onthe 23/03/99

3.5 SUGGESTIONS FOR FURTHER WORK BASED ON THE 1993/1998SURFACE WATER MONITORING PROGRAM.

The surface water monitoring program has indicated that rehabilitation objectives

have been met in terms of reducing pollutant loads from sources within the site, and

in reducing the impact on the aquatic ecosystems within the Finniss River system.

Suggested areas for future monitoring and research include:

• Maintain contaminant load estimates at GS 8150097.On-going load estimation at GS 8150097 will provide continuity of one measure of

overall rehabilitation performance, notwithstanding the shortcomings of relating

annual contaminant load estimates to ecological impact. The load data will provide a

sample number

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

norm

alis

ed m

etal

con

cent

ratio

ns

0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

normalised Cu concentrationsnormalised Fe concentrationsnormalised Mn concentrationsnormalised Ni concentrationsnormalised Zn concentrations


benchmark for any further rehabilitation or other mining activities that may impact on

contaminant transport processes and overall loads down the East Finniss River.

• Consolidate contaminant status of fluvial sediments in the East Finniss andFinniss Rivers.

The 1993 sediment survey on the East Finniss revealed a significant inventory of

contamination in the sediments of the river downstream of the former mine site. Any

further remediation or attenuation of contaminant transport from Rum Jungle must

have due regard for this repository of contamination downstream.

• Undertake groundwater assessment and modelling, especially in thevicinity of the Diversion Channel and waste rock dump.

The information collected since rehabilitation indicates that contaminant transport

from the site has been greatly reduced. There are discrepancies in contaminant load

estimates between GS 8150097 and GS 8150200, but these are most likely a

function of errors in flow estimation and sample integrity/representativeness between

the two stations. Of greater concern is the discrepancy between the overall load

measurement and the current best estimate of on-site contributions to this load. The

contribution from Dysons is considered low (<1 t pa copper) and well represented by

data collected at the open cut inflow site GS 8150213. The contribution from the

open cuts is principally drawn from the hypolimnetic waters at the base of Whites

water body (see Chapter 4) and will continue to contribute ~3 t pa of copper until this

source is exhausted.

Leachate discharge from the toe drains of the waste rock dumps is driven by

rainwater infiltration of the covers. The total area of the covers (and batters) for

Whites and Intermediate is approximately 30 ha. With a rainfall of ~1500 mm pa, an

infiltration rate of (say) 10% (total of 45 ML) and a water quality of 30 mg/L copper

measured in the leachate, a rough estimate of copper export from this area due to

infiltration is a fairly modest 1.4 t pa copper. That is, a load of some 4-5 t of copper

that exits the site annually can be explained in terms of the on-site partitioned

sources (Dysons, open cuts and waste rock dump infiltration). This leaves a

significant discrepancy between this load and the annual totals measured


consistently (~12 tonne copper) further downstream at GS 8150200 and GS

8150097.

Data interpretation and discussion in section 3.3 clearly demonstrates that much of

this otherwise unexplained contaminant load is derived from the Diversion Channel

area adjacent to the waste rock dumps in the latter months of each wet season. This

period corresponds to a time when groundwater levels are at their highest elevation.

This may provide the key to understanding other transport mechanisms and

contaminant sources on-site that give rise to the balance of the load mobilised off-

site each year.

A thorough examination of the local groundwater regime would determine whether

this source of contamination resides within the groundwater and what processes

operate to transport this contamination to the East Branch of the Finniss River.


4. WATER QUALITY IN WHITES AND INTERMEDIATE OPEN CUTSM D LAWTON

Department of Infrastructure, Planning and Environment, Darwin NT.

R OVERALLEWL Sciences, Darwin NT

4.1. OVERVIEW

After the cessation of mining, Whites Open Cut (WOC) and Intermediate Open Cut

(IOC) were partially backfilled and then flooded. WOC, the larger of the two water

bodies, reached a maximum depth of 110 m as an open cut, but is currently about

50-60 m deep. Its surface diameter is approximately 360 m. IOC is smaller and less

circular in plan view than WOC, with a ‘diameter’ of 210-270 m and an original depth

of about 57 m (see cover photo).

In 1984 and 1985, polluted water from WOC was pumped from depth and treated

with lime as part of a process to neutralise the acidic pH and to co-precipitate

dissolved heavy metals. This precipitate was removed by filtration and the treated

water, with contamination largely removed, was returned to the open cut where it

established a lower density layer on top of the denser untreated water. The treated

layer was low in heavy metals and ultimately extended to a depth of about 20 m.

This program of work has been extensively reported previously in the Final Project

Report (Allen & Verhoeven 1986).

The layering or stratification of less dense treated water on the more highly

contaminated, denser water was a feature of the water body for the first 10 years or

so after rehabilitation. Stratification is still a feature of the water body but the ‘treated

water layer’ is long gone and stratification is due to both the thermal gradients in

response to the annual cycle of insolation and the persistence of an ‘un-treated

water’ layer deep below the surface. The un-treated water is so named since its

current composition is similar in quality to the open cut waters prior to treatment in

1985-1986. The boundary or zone of maximum gradient in density differential

between the two ‘layers’, one being the upper mixed zone or epilimnion and the

other being the denser lower zone or hypolimnion is referred to as the pycnocline. It

has been previously reported (Kraatz 1998) that the majority of contamination within


the open cut precinct is held within the hypolimnetic waters of WOC and a relatively

insignificant amount in IOC. For that reason, the following discussion is largely

restricted to contaminant transport mechanisms and processes understood to be

operating in WOC and of those contaminants, focus is placed on copper.

It was estimated that in October 1997 the IOC contained, in a dissolved phase, less

than 200 kg of copper, approximately 1.5 t of manganese, less than 100 kg of zinc

and about 350 kg of nickel. This calculation was based on detailed profile data and

the assumed hypsographic (depth vs volume) relationship for the water body

documented in the 1998 Kraatz Report. In contrast, WOC at the same time

contained, or held in the water column at least, 14.5 t of dissolved copper, over 50 t

of manganese, 1.5 t of zinc and approximately 4.5 t of nickel.

Flow diversion works were constructed in the 1983-86 rehabilitation works to prevent

the first flushes of each wet season from entering the open cuts. These early flows

contain elevated levels of pollutants from the upstream areas of the site, including

Fitch Creek and run-off from the Dysons Overburden Heap and Open Cut landform.

These early season flows are directed through the diversion channel. Later in the

wet season when flows are higher, flow from the upper catchment is split between

this diversion channel and the open cuts (refer Section 4.4). Each wet season, flows

directed through WOC and IOC result in dilution and lowering of any contaminant

concentrations and conductivity in the upper mixed layers. The depth in WOC to

which the lower density water extended in April 1998 was about 32 m below the

water’s surface (or 28 m AHD).

4.2. PROFILING OF WHITES OPEN CUT

Physico-chemical profiles of the water column in the open cuts were undertaken over

1993-1998 in order to monitor the inventory of pollutants within the open cuts and to

assess the effectiveness of the annual wet season flushing of the open cuts.

Dry season cooling (May-August) of the water column and wind shear at the surface

of the water bodies promotes isothermal conditions from the surface down to the

pycnocline at this time of year. The temperature gradient within the hypolimnion itself


follows a ‘lag-phase’ heating and cooling regime because of its relative isolation from

surface temperature fluctuations but the behaviour of this density layer is

overwhelmingly driven by its very high solute concentration. As a result of the dry

season decay of thermal stratification, small volumes of highly contaminated

hypolimnetic water are mixed with the surface waters as energy is transferred from

the surface to the interface at depth. Isopleths of temperature, pH, conductivity and

solute concentrations in the surface waters of WOC (to approximately 34 m AHD)

are presented in Figures 4.1 to 4.6. These isopleths cover the period from January

1993 to December 1995 when detailed profiles were taken on a regular fortnightly

rather than monthly basis.

Temperature

Temperature profiles in WOC down to 32 m AHD indicate that brief isothermal

periods can occur during the wet season when inflows to the water bodies are high

and turbulent energy is correspondingly high. Temperature stratification occurs

(Figure 4.1) from the end of the wet season to early in the dry. The cooler dry season

weather and prevailing SE winds bring about a weakening and temporary breakdown

in epilimnetic thermal stratification. Surface water temperatures drop on average

~0.5°C each fortnight at this time of year.

pH

The most notable trend to be seen by plotting pH isopleths for WOC is the steady

acidification of the surface water during the cooler months of each dry season

(Figure 4.2). Surface waters with a pH of up to 6.2 in February drop down by about 2

pH units over a depth of about 20 m by May in each year (Figure 4.2).


Figure 4.1 Isopleth diagram of Whites Open Cut temperature changes with depth (to 32 mAHD) from January 1993 to December 1995

Figure 4.2 Isopleth diagram of Whites Open Cut pH changes with depth (to 30 m AHD) andtime from January 1993 to December 1995

30

35

40

45

50

55

60

Dept

h (A

HD m

)

35

40

45

50

55

60D

epth

(AH

D m

)

Jan 93 July 93 Jan 94 July 94 Jan 95 Dec 95July 95

Date


Copper

During the heavy rains and run-off of each wet season, dilution and mixing occurs in

WOC (Figure 4.3). Copper concentrations can be reduced to 0.1 mg/L in the surface

10-15 metres. However, at the cessation of the wet season the copper concentration

begins to increase and can rise to >1.0 mg/L over a depth of 30 m AHD (Figure 4.3).

Manganese

Similar trends with manganese occur as with copper. Manganese concentrations

range from 0.5-1.5 mg/L in the surface waters during the wet season. Maximum

concentrations of up to 2.5 - 4 mg/L in the late dry/wet season build-up are seen

(Figure 4.4).

Figure 4.3 Isopleth diagram of Whites Open Cut copper concentrations (mg/L) with depth (to36m AHD) and time from January 1993 to December 1995

Zinc

Zinc concentrations in the waters above 30 m AHD are less variable in terms of

absolute amounts than copper and manganese concentrations. This is a function of

40

45

50

55

60

Dep

th (A

HD

m)


the lower concentration of this contaminant below the pycnocline (6-8 mg/L for zinc

in contrast with ~200 mg/L manganese and 50-60 mg/L copper in the hypolimnetic

waters). Dilution of the surface waters of WOC as a consequence of wet season

flushing reduces zinc contamination to below 0.1 mg/L (Figure 4.5). As is the case

with copper and manganese, elevations in zinc concentrations occur as a function of

mixing from highly contaminated sub-surface water brought about by isothermal

conditions during the cooler months. Maximum concentrations of zinc in surface

waters during the dry season are ~0.2 mg/L.

Conductivity

Dilution and concentration trends are similar for conductivity as for metal

concentrations. Uniform conductivity is seen in the water column down to 34 m AHD

during the dry season period (Figure 4.6). Rains during the wet season cause

dilution and flushing of the surface waters with ‘cleaner’ water of lower conductivity

from the upper catchment of the East Finniss. Cooling during the dry season allows

the more concentrated bottom solution to mix with the surface waters resulting in

high electrical conductivities (up to 500 µS/cm) by the end of the dry season. As only

about 3% of the water from WOC evaporates from the surface each dry season,

based on a drawdown of ~2 m, evaporative concentration of the upper mixed layer

water alone would result in a rise of less than 10 µS/cm, not the 250 µS/cm seen in

Figure 4.6.


Figure 4.4 Isopleth diagram of Whites Open Cut manganese concentrations (mg/L) withdepth (to 36m AHD) and time from January 1993 to December 1995

Figure 4.5 Isopleth diagram of Whites Open Cut zinc concentrations (mg/L) with depth (to 36m AHD) and time from January 1993 to December 1995

40

45

50

55

60

Dep

th (A

HD

m)

40

45

50

55

60D

epth

(AH

D m

)


Figure 4.6 Isopleth diagram of Whites Open Cut conductivity (µµµµS/cm) with depth (to 32 mAHD) and time from January 1993 to December 1995

4.3. WHITES COPPER INVENTORY AND THE DEPTH OF THE PYCNOCLINE

Several tonne of dissolved copper have exited the open cuts each wet season of the

period monitored, as confirmed by monitoring data collected at GS 8150212.

Gauging station GS 8150213 monitored flow and loads entering WOC over the

period 1993-1998. The measured annual copper load estimates entering and exiting

the open cut precinct varied from year to year. The annual net copper contaminant

load sourced from the open cuts during the period of 1993/1994 and 1997/1998

ranged in estimates from 1.1 to 4.0 tonne annually (mean 2.7 t, std dev 1.2).

Over a period of 12 years, the depth of the pycnocline in WOC was lowered by 14 m

(from 41 to 27 m AHD). This represents an average erosion of the bottom

hypolimnetic waters of about 1.2 m/y. The bottom of WOC was estimated to be at

~20 m AHD by reference to bathymetric data collected by the Department of Mines

and Energy at the time of rehabilitation in 1983-1986. By trend analysis on the data

collected to date, if the pycnocline continues to be lowered at the rate of ~1.2 m/y it

will reach the bottom of the open cut in 2003. Contaminated lower waters should by

then be fully flushed from the system. The major uncertainty associated with this

35

40

45

50

55

60De

pth

(AHD

m)


estimate is in the bathymetry of the pit itself. No thorough sounding or checking of

the supplied information was made for either Whites or Intermediate pit over the

course of this project and there may well be some deeper areas within the water

body that will have residual untreated water. Nevertheless, given the known (and

visible in the dry season) benched structure of the original pit, the majority of

contaminated water has already been flushed out and the remainder is diminishing

year by year.

Using the value of a mean annual deepening of the pycnocline of 1.2 m, and further

assuming an average dissolved copper concentration below the pycnocline of ~55

mg/L in hypolimnetic water, it is estimated that 3.3 t of copper was removed annually

from WOC. Mixing of some of the dense waters across the pycnocline into the less

dense surface waters by a combination of diffusion and vertically transmitted

turbulence has led to a gradual decline in the volume of the highly contaminated

bottom waters of WOC. Figure 4.8 shows the gradual reduction in the inventory of

dissolved copper from below the pycnocline in WOC from August 1986 to April 1998,

as the inventory was depleted from a total of ~ 48 t to ~ 13 t.

The average total mass of dissolved copper above the pycnocline in WOC from 27

August 1986 to 29 April 1998 has been calculated to be 1.15 t (std. dev. 0.59). An

annual cycle was demonstrated to occur with maximum copper inventories (up to 2.5

t) recorded late in the year (November to January) and minimum inventories

(average ~0.5 t) between March and May following the wet season flush (Figure 4.9).


Y ear

198 6 19 87 1 988 1 989 1 990 1991 199 2 199 3 199 4 1 995 1 996 1 997 1 998

Dep

th o

f pyc

nocl

ine

(AH

D) (

m)

2 4

2 6

2 8

3 0

3 2

3 4

3 6

3 8

4 0

4 2

Figure 4.7 Depth (AHD) of pycnocline in Whites Open Cut vs. time 27/08/1986 to 29/04/1998

date

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998

Cu

(t)

0

10

20

30

40

50

60

Cu (t) above pycnoclineCu (t) below pycnoclinebelow pycnocline regression

Figure 4.8 Copper inventory (in t) in Whites Open Cut above and below the pycnocline from1986-1998

(Y axis scale to accommodate below-pycnocline tonnages)


d a te1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8

Cu

(t)

0

1

2

3

4

C u in v e n to ry in W O C a b o v e p yc n o c lin e

2 6 /0 3 /9 2

2 6 /1 1 /9 2

2 6 /0 5 /9 3

0 2 /0 3 /9 4

2 9 /0 4 /9 4

2 1 /0 5 /9 6

1 3 /1 2 /9 5

2 7 /1 0 /9 7

1 2 /1 2 /9 6

1 0 /0 1 /9 5

2 9 /0 4 /9 82 9 /0 4 /9 7

9 /1 2 /9 3

1 4 /0 3 /9 5

1 2 /1 0 /9 0 2 1 /1 0 /9 1

0 8 /0 5 /9 13 1 /0 5 /9 0

Figure 4.9 Copper inventory in Whites Open Cut above the pycnocline (1990-1998)

4.4. WHITES AND INTERMEDIATE OPEN CUT WATER QUALITY

The rehabilitation water quality objectives for WOC and IOC were outlined in Table

3.3 of the Final Project Report (Allen & Verhoeven 1986). Those targets are detailed

in Table 4.1 together with pre-rehabilitation data and the analyses from late 1997

and early 1998. The key failure to meet the original targets evident in this data is the

inability to maintain a circum-neutral pH in WOC. The reason for this seasonal low

pH occurrence was outlined in section 4.2. This target failure reflects the flawed

concept that underpinned the rehabilitation water treatment objective for WOC that

there would be sufficient density differential between treated water and untreated

water to maintain indefinitely a stable separation or buffer zone (Final Project Report

– section 7.2 Allen & Verhoeven 1986). The water treatment process undertaken for

IOC was largely successful, but this was achieved as a consequence of the lower

contaminant load in the water and the smaller size/volume of IOC.


Table 4.1 Comparison of pit water quality prior to rehabilitation with post-rehabilitation andtarget pit water quality

Before treatment* Post-rehabilitation*** Target(both)**

April 1998 October 1997

Solute (mg/L) Whites Intermediate Whites Intermediate Whites Intermediate

Copper 55 60 0.2 0.2 0.69 0.19 1.5

Iron 440 0.9 0.06 0.02 0.44 0.06 1.0

Manganese 230 53 0.74 0.66 2.26 0.65 1.0

Zinc 8 6.5 0.04 0.04 0.15 0.08 5.0

Chromium 0.55 0.08 - - - - 0.1

Cadmium 0.21 0.04 - - - - 0.1

Arsenic 0.45 0.003 - - - - 0.05

Barium <0.002 <0.02 - - - - 1.0

Lead 0.6 0.038 - - - - 1.1

Silver 0.11 0.13 - - - - 0.1

Mercury <0.001 <0.001 - - - - 0.005

Selenium <0.005 <0.005 - - - - 0.001

Nickel 15 12 0.09 0.09 0.31 0.21 1.0

Cobalt 15 13.6 - - - - 1.0

Calcium 445 200 6 4 15 15 1000

Sulfate 8400 2800 64 51 171 145 2000

pH 2.6 3.7 6.2 6.5 4.2 6.2 7.0

Radioactivity (Bq/L) 87.4 32.0 refer Table 4.2 0.19

* From Alcock and Connolly (1986), with samples taken from 15 m below the surface of the water** From Allen and Verhoeven (1986) - target equal to or better than.*** Samples collected from 20 m below the surface on specified dates

4.5. RADIOLOGICAL ANALYSIS OF WHITES AND INTERMEDIATE OPEN CUTS

As a ‘one-off’ exercise to report on the radiological status of waters at the

rehabilitation site, water samples were collected from WOC and IOC at the surface

and from a depth of 35 m on 12 December 1996. Surface samples were also

collected on 8 November 1996. Radiological analysis data from these samples are

presented in Table 4.2.


Table 4.2 Radioactivity analysis results from Whites and Intermediate Open Cuts

Date Sample Gross alphaconcentration

(Bq/L)

Gross betaconcentration

(Bq/L)1

corrected

Totalpotassium

(mg/L)

Potassium-40beta-activity

(Bq/L)

Radium-226concentration

(Bq/L)

WOC 0 m 0.96 ± 0.06 0.56 ± 0.02 - - < 0.018/11/96

IOC 0 m 0.15 ± 0.03 0.13 ± 0.01 - - < 0.01

WOC 0 m 0.48 ± 0.04 0.49 ± 0.02 2.0 0.056 -

WOC 35 m 118 ± 4 162 ± 2 9.7 0.27 -

IOC 0 m 0.09 ± 0.02 0.12 ± 0.01 0.8 0.022 -

12/12/96

IOC 35 m 1.3 ± 0.3 1.2 ± 0.1 4.0 0.11 -

1 Gross beta results have been corrected for potassium-40 beta activity

The Australian Drinking Water Guidelines (NH&MRC 2001) recommend a risk

assessment process based on dose response to establish whether there is a human

health concern with radiological contamination. A flow diagram at Figure 4.1 Section

4.7 of Chapter 4 in the NH&MRC document is proffered as a decision support tool to

assist in this process. In that figure, if gross alpha or beta radioactivity exceeds 0.5

Bq/L, then further analysis should be undertaken to identify the particular sources of

the radioactivity to allow for annual dose estimates to be made.

For the samples collected from WOC in 1996, the gross alpha levels of all samples

were near or above the trigger of 0.5 Bq/L. With respect to radium-226,

concentrations measured in the open cuts surface waters were <0.01 Bq/L. Prior to

rehabilitation, samples taken from 15 m below the water surface of WOC and IOC

were analysed to have radium-226 concentrations of 87 Bq/L and 32 Bq/L

respectively. The sample collected from 35 m below the surface of WOC on 12/12/96

was analysed with a slightly higher radium-226 concentration of 118 Bq/L whereas

the sample taken from IOC on the same day was far lower (1.3 Bq/L) than the

respective pre-rehabilitation levels.

Contaminated water that exits WOC is diluted when entering the East Branch of the

Finniss River and further diluted when it reaches the East Branch’s confluence with

the Finniss River as evidenced by data collected at GS 8150204 and discussed in

Chapter 3. During a year of average rainfall, a three-fold dilution from the open cuts

(GS 8150212) to downstream (GS 8150097) occurs. From GS 8150097 to GS

8150204, an average 25-fold dilution occurs. Taking these estimated average


dilution factors into account and assuming that predominantly only surface water is

flushed from the open cuts, the dilution that occurs over an average wet season will

reduce the radiological level of water in the Finniss River to well below levels

regarded as trigger levels for further assessment procedures. The discussion at 3.3

regarding the scheduling of copper contaminant export from WOC to the East

Finniss, as monitored at GS 8150212 and GS 8150200 is relevant here as the same

export process is in operation.

4.6. PHYSICAL-CHEMICAL ANALYSIS OF WHITES AND INTERMEDIATE OPENCUTS

Data from WOC and IOC physical-chemical profiles taken in April 1998 are

presented in Tables 4.3 and 4.4 respectively. Solute concentrations and conductivity

of WOC remained relatively constant to 28 m AHD where there is a narrow band of

moderately contaminated water. Below this depth is the highly contaminated

hypolimnetic water. Similar stratification is noticeable in IOC but, although

conductivity increases significantly below 25 m AHD, contaminant concentration

increases are far less pronounced. For copper, concentrations decrease with

increasing depth.


Table 4.3 Solute concentrations (mg/L) and water quality parameters of Whites Open Cut,April 1998

AHD(m)

Depth(m)

Temp(0 C)

pH % satDO

DO(mg/)

Cond(µµµµS/cm)

Ca(mg/L)

Mg(mg/L)

SO4(mg/L)

Cu(mg/L)

Mn(mg/L)

Zn(mg/L)

Ni(mg/L)

Fe(mg/L)

Al(mg/L)

60.01 0 30.8 6.8 89 6.6 157 4 13 61 0.10 0.31 0.04 0.06 0.46 0.0955.01 5 30.3 6.5 78 5.9 172 0.10 0.34 0.05 0.06 0.44 0.1350.01 10 29.6 6.1 69 5.3 110 3 8 41 0.10 0.32 0.03 0.06 0.35 0.1845.01 15 28.9 5.7 67 5.2 115 0.10 0.46 0.04 0.06 0.19 0.1340.01 20 28.2 5.4 71 5.5 151 6 11 64 0.20 0.74 0.04 0.09 0.06 0.1335.01 25 28.2 5.4 69 5.4 171 0.20 0.78 0.05 0.08 0.07 0.1430.01 30 27.9 4.4 50 4.6 274 12 20 137 0.80 2.45 0.11 0.23 0.13 1.8829.01 31 27.7 4.1 33 3.6 458 1.30 4.42 0.18 0.37 0.21 5.228.01 32 27.7 3.7 0.1 993 3.10 17.65 0.42 1.01 0.87 14.827.01 33 27.6 3.8 0 0.0 7168 54 244 5.49 18.55 378 21526.01 34 27.4 3.8 0 0.0 7478 60 269 7.40 16.70 404 22625.01 35 27.3 3.8 0 0.0 7558 481 902 8270 62 254 7.75 19.00 420 236

Table 4.4 Solute concentrations (mg/L) and water quality parameters of Intermediate OpenCut, April 1998

AHD(m)

Depth(m)

Temp(0 C)

pH % satDO

DO(mg/)

Cond(µµµµS/cm)

Ca(mg/L)

Mg(mg/L)

SO4(mg/L)

Cu(mg/L)

Mn(mg/L)

Zn(mg/L)

Ni(mg/L)

Fe(mg/L)

Al(mg/L)

57.92 0 31.8 6.9 92 6.8 143 4 11 53 0.20 0.38 0.03 0.11 0.37 0.2252.92 5 31.0 6.7 86 6.4 141 0.10 0.37 0.03 0.10 0.38 0.2147.92 10 30.7 6.5 80 6.0 130 4 10 48 0.10 0.37 0.02 0.08 0.33 0.2142.92 15 28.8 5.6 76 5.8 124 0.20 0.66 0.04 0.09 0.03 0.1537.92 20 28.5 5.5 78 6.0 125 4 9 51 0.20 0.66 0.04 0.09 0.02 0.1632.92 25 28.5 5.4 74 5.8 137 0.20 0.72 0.04 0.13 0.03 0.1627.92 30 28.1 5.3 64 5.2 161 6 12 71 0.30 0.91 0.06 0.15 0.06 0.1826.92 31 27.8 5.0 55 4.7 240 0.40 1.19 0.10 0.19 0.06 0.3325.92 32 27.6 4.7 35 3.4 418 0.60 1.65 0.20 0.30 0.06 0.4824.92 33 27.2 4.5 0 0.1 1104 1.10 3.54 0.95 0.98 0.11 1.1423.92 34 27.0 4.8 0 0.0 2278 1.10 9.60 2.01 1.83 16.05 1.5522.92 35 26.8 5.7 0 0.0 3478 250 322 2410 0.10 9.75 0.74 1.14 25 0.35


The complete in-situ profiles of WOC and IOC taken in April 1998 are shown in

Tables 4.5 and 4.6 respectively. For WOC there is no indication of a distinct thermal

stratification and pH shows relatively little variation until a depth of 31-32 m

whereupon there is a marked drop in this parameter along with the dissolved oxygen

concentration and a concomitant increase in solute concentrations and

contaminants.

The IOC water column follows a similar trend in temperature and pH with relatively

small variations over depth. However, as with WOC, the percent saturation of

dissolved oxygen also drops rapidly from 60% at 30.5 m to 1% at 32.5 m depth. The

increase in conductivity for IOC is not as marked as WOC, but there is nevertheless

a distinctive anoxic, hypolimnetic zone at the bottom of the water body that contains

elevated sulfate, iron and manganese concentrations and only minor quantities of

other contaminants. Profile data, such as has been collected at this depth, indicates

that there is a pH rise with depth through this bottom layer. These features are most

probably an artefact of the rehabilitation treatment performed on the IOC water body

in 1985-1986 (Final Project Report 1986 – section 7.3 Allen & Verhoeven 1986)

whereby lime was added to the ‘fully mixed’ pit waters, followed by in-situ settlement

and subsequent sludge removal. There is a strong possibility that mixing by bubble

diffuser was incomplete at the time of lime addition, notwithstanding the anchoring of

the compressed air manifold on the ‘bottom’ of the pit. The sludge removal would

certainly have been less than 100% efficient once settlement of the precipitate was

deemed to have reached completion. These bottom waters have been eroded on a

seasonal basis much as the hypolimnion of WOC has eroded since rehabilitation but

without the same consequence of high contaminant transport to the Finniss system.


Table 4.5 Profiles of temperature, pH, EC25 and dissolved oxygen at 1m (and 0.5m)intervals to a depth of 35 m taken in Whites Open Cut in April 1998

Depth(m)

Temp(oC)

pH %SATD.O.

Cond.(µµµµS/cm)

D.O. mg/L

0.0 30.82 6.80 89 157 6.601.0 30.84 6.78 88 157 6.572.0 30.82 6.76 88 158 6.563.0 30.79 6.74 88 159 6.564.0 30.53 6.59 83 157 6.205.0 30.25 6.48 78 172 5.896.0 30.00 6.34 75 144 5.687.0 29.88 6.28 74 138 5.578.0 29.72 6.18 71 121 5.409.0 29.62 6.10 70 113 5.31

10.0 29.55 6.05 69 110 5.2911.0 29.44 5.99 69 107 5.2512.0 29.37 5.96 69 105 5.2513.0 29.24 5.91 68 108 5.1814.0 29.15 5.85 67 109 5.1215.0 28.86 5.74 67 115 5.1916.0 28.59 5.58 69 119 5.3517.0 28.45 5.50 70 118 5.4418.0 28.30 5.42 71 122 5.5319.0 28.24 5.39 71 138 5.5720.0 28.22 5.41 71 151 5.5221.0 28.21 5.42 70 159 5.4422.0 28.22 5.44 69 164 5.3923.0 28.23 5.45 69 170 5.3924.0 28.21 5.45 69 171 5.3925.0 28.20 5.43 69 171 5.3626.0 28.19 5.41 68 171 5.3327.0 28.17 5.38 68 180 5.2828.0 28.09 5.26 64 182 5.2129.0 27.99 4.80 61 199 5.0429.5 27.92 4.51 59 244 4.8030.0 27.86 4.42 50 274 4.6430.5 27.74 4.25 46 395 3.8931.0 27.70 4.14 33 458 3.5931.5 27.67 4.00 1 571 2.6032.0 27.65 3.72 0 993 0.0832.5 27.60 3.86 0 5308 033.0 27.57 3.80 0 7168 033.5 27.51 3.80 0 7408 034.0 27.44 3.79 0 7478 034.5 27.35 3.80 0 7538 035.0 27.27 3.79 0 7558 0

*Inlet (GS 8150213) 32.56 6.64 109 447 7.89

* Measurements taken at inflow on day of profile recording


Table 4.6 Profiles of temperature, pH, EC25 and dissolved oxygen at 1m (and 0.5m)intervals to a depth of 35m taken in Intermediate Open Cut in April 1998

Depth(m)

TEMP(oC)

pH % SATD.O.

COND(µS/cm)

D.O.(mg/L)

0.0 31.83 6.94 92 143 6.761.0 31.77 6.90 91 143 6.652.0 31.29 6.84 89 144 6.613.0 31.20 6.80 89 142 6.564.0 31.09 6.79 88 142 6.535.0 30.97 6.73 86 141 6.406.0 30.91 6.67 85 139 6.327.0 30.86 6.65 85 138 6.308.0 30.81 6.63 85 138 6.319.0 30.76 6.60 83 135 6.22

10.0 30.69 6.51 80 130 6.0111.0 30.55 6.42 80 124 5.9712.0 30.07 6.20 75 116 5.6813.0 29.53 5.87 74 120 5.6514.0 29.02 5.68 75 123 5.7915.0 28.78 5.60 76 124 5.8416.0 28.65 5.57 77 124 5.9317.0 28.59 5.56 77 124 5.9918.0 28.55 5.55 77 125 6.0019.0 28.55 5.55 77 124 6.0020.0 28.52 5.54 78 125 6.0221.0 28.50 5.52 77 128 5.9622.0 28.48 5.50 76 129 5.9123.0 28.48 5.48 76 131 5.9224.0 28.46 5.46 75 132 5.8425.0 28.47 5.42 74 137 5.7526.0 28.45 5.38 74 138 5.7627.0 28.42 5.35 73 141 5.6628.0 28.35 5.38 70 138 5.5929.0 28.27 5.39 67 141 5.4530.0 28.08 5.33 64 161 5.2330.5 27.98 5.24 60 183 5.0431.0 27.83 4.95 55 240 4.6631.5 27.73 4.81 43 306 4.2932.0 27.55 4.74 35 418 3.3932.5 27.44 4.73 1 536 2.7633.0 27.24 4.45 0 1104 0.1133.5 27.11 4.54 0 1728 034.0 27.03 4.80 0 2278 034.5 26.88 5.30 0 2878 035.0 26.78 5.69 0 3478 0

*Inlet 32.20 6.71 94 152 6.83

* Measurements taken at inflow from Whites on day of profile recording


4.7 SUGGESTIONS FOR FURTHER WORK

• Update status of the stratification profiles for each open cutThe most recent depth profiles undertaken in the water bodies were in April 1998. A

prediction has been made in this report regarding the projected rate of contaminated

water transport from the base of WOC water body. An update on the current status

of the water bodies would provide confirmation or otherwise of this prediction. Once

contamination has been ‘removed’ from WOC, annual copper load estimates as

monitored at GS 8150097 would be expected to diminish by approximately 2-3 t, all

other site contributions to the overall copper load remaining the same.

• Investigate issue of contamination (radioactivity/sediments) at the base ofWhite's open cut

Associated with the erosion of the contaminated hypolimnetic waters in WOC water

body is the new dynamic equilibrium that will be established between the bottom

sediments and the water column. From documents pertaining to the mine operation

and the early rehabilitation works, it is clear that highly polluted material, inclusive of

tailings, was dumped into WOC. It is suggested that some measure of the nature of

the water column/sediment interaction be made as it represents a ‘new’ situation at

the site. This was not anticipated in the original rehabilitation works, and it is a

situation that may provide a new conduit for contaminant transport (inclusive of

radionuclides) from the site via the water column.


• Model enhanced flushing of recessional flows from site by accessing'clean' water from Intermediate pit

The data presented in this report indicate that although contaminant transport has

been much reduced as a result of the rehabilitation works the contaminant

concentrations monitored are still well in excess of ecosystem tolerance for a

significant distance downstream of the former minesite. There is potential to provide

a benefit to downstream biota by a reduced frequency of elevated contaminant

concentrations during first flush and recessional flows. A number of scenarios could

be examined that involve the feasibility of increased storage capacity for the IOC

water body and the passive release of this increased inventory of clean water to late

wet season recessional flows in the East Branch. Use of such models as the ANSTO

AQUARISK package might be used to assist in the determination of the

effectiveness of such options.


5. VEGETATION DIEBACK ON DYSONS OPEN CUT; IMPLICATIONS,CAUSAL MECHANISMS AND OPTIONS FOR REMEDIATION

N W MENZIES AND D R MULLIGAN,Centre for Mined Land Rehabilitation, University of Queensland

5.1. INTRODUCTION

The spread of vegetation dieback on the surface of the rehabilitated Dysons Open

Cut at the Rum Jungle rehabilitated site has been a source of concern for some

years. The objective of the current study was to expand the scope of previous

assessments and more fully investigate the causes and implications of the dieback

(including implications for other rehabilitated areas at the site), out of which options

for remediation can be more clearly identified and justified.

A comprehensive sampling program was undertaken and the conclusion drawn is

that plant death has been caused by copper toxicity. The mechanism by which this

has occurred is the upward capillary movement of acidic, copper-contaminated

solution from the underlying copper Heap leach waste into the soil layers above.

Contamination of the surface soil and resultant plant death has occurred most rapidly

where the depth of soil is shallowest, itself more a consequence of uneven capping

at the outset rather than a result of significant surface erosion. The bare/vegetation

interfaces where copper toxicity causes plant death during the growing season are

expected to move progressively into the vegetated areas, the limits of the expansion

being dictated by the sub-surface distribution of the copper-laden Heap leach waste.

While the dieback at other areas such as Whites Dump is also a consequence of

inadequate capping over an acidic waste, the underlying waste does not represent a

major source of copper contamination. The affected area in this instance is localised

to a pocket of very shallow soil cover, and would not be expected to expand further.

In terms of remediation, the options are to do nothing, cover with rock mulch, or

completely reinstall the capping with an appropriate sequence of materials. The final

choice in terms of these options will be in accordance with principles that are

established for maintaining vacant Crown Land.


In time, the levels of copper in the drainage will increase if nothing is done or if only

rock mulch is applied to the surface. The latter treatment will, however, provide

increased surface protection and hence reduce the risk of major exposure of the

underlying acid-forming material. Whether this offers any advantages over the do

nothing approach depends on a more accurate assessment of the erosion potential

of the denuded surface. The third and most costly option is to reconstruct the cover,

this time using a more effective capillary break. This may not, however, have to be

installed over the entire surface, but rather only over that area which overlays the

copper Heap leach material. The extent of this area needs to be determined before

the full cost of remediation can be estimated and indeed before the final limits of the

dieback expansion will be known.

5.2. BACKGROUND

Dysons Open Cut was first used in 1961 as the disposal site for the tailings from the

Rum Jungle rehabilitated site. It was subsequently used as a disposal site for low

grade ore from the copper Heap leach pile, the associated soils from the Old Tailings

Dam and the Heap leach area, and the contaminated materials from Copper Creek

and Tailings Creek (Allen and Verhoeven, 1986) (see Figure 5.1).

Figure 5.1 Site layout of the Rum Jungle rehabilitated site

The rehabilitation program commenced with the covering of the in-pit tailings with

geotextile fabric. Tailings from the Old Tailings Dam area and the oxide and sulfide

ores from the copper Heap leach pile were then placed on top and the infilled


surface reworked to produce a concave shape enabling collection of water into a

rock-armoured central drainage system. The rehabilitation of the site included the

design and installation of a cover system, which consisted of three layers, or zones.

A compacted clay layer to minimise the ingress of oxygen and water (Zone 1A); a

gravelly layer to provide free drainage of the water from the surface of the

compacted clay seal (Zone 1B); and a soil layer to allow the establishment of

vegetation and prevent surface erosion (Zone 2A). The surface was then sown with

introduced pasture grasses.

Since 1989 in particular, staff of the Department of Infrastructure, Planning and

Environment (DIPE) have noted that areas of vegetation dieback were occurring on

the surface of the rehabilitated pit. These areas were reported as occupying between

10 and 30% of the site. In response to these observations, Woodward-Clyde

conducted an initial investigation and presented their findings in January 1994 in a

report entitled “Rum Jungle – Dysons Open Cut soil and vegetation dieback study -

Phase 1 Report”. In July 1995, geotechnical staff from the Department of Transport

and Works Construction Agency conducted a further investigation into the dieback of

vegetation. The aims of this latter study were to determined whether or not the

protective cover layers were constructed to design specifications (with particular

reference to the depths of cover layers) and to get some indication of the

compaction/density of the infiltration resistant layer (Zone 1A). The scope of their

brief investigation included:

• Visual inspection and assessment of the site;

• Excavation and logging of auger holes in both vegetated and unvegetated areas;

and

• Sampling and testing of soils for pH.

At the time of this latter investigation, four main dieback areas existed, the most

significant of these occurring at the top of the slope in the southwest section of the

site. The observations that were made in their 1995 report included:

1. The uppermost Zone 2A material was non-existent in unvegetated areas.

2. Zone 1B and 1A materials were generally close to thickness specification

requirements.


3. pH testing at one auger hole showed that the cover layers were acidic with

only a marginal difference between the pH of Rum Jungle tailings (pH 3.4)

and cover layers (pH 3.8 – 4.2).

4. Some surface soils in unvegetated areas behind contour banks showed salt

efflorescence.

5. A visual assessment of the density rated the Zone 1A material as too dense.

6. No shrinkage cracks were noticed in the sides of the auger holes.

From these observations, the authors concluded that the thin upper cover layers in

the dieback areas were due to insufficient material placed during construction, and/or

erosion occurring since construction. They then postulated that possible causes of

the dieback could be:

• The non-existent Zone 2A cover material;

• Low pH levels in the upper cover layers; or

• Metal toxicity in the upper cover layers

5.3. OBJECTIVES

Since most of the conclusions drawn from the earlier studies were based on very

limited sampling and/or observation alone, the former DLPE requested a further

staged investigation into the rehabilitation works on Dysons Open Cut.

Stage 1: Implications of diebackTo determine the implications of vegetation dieback on:

• Long term integrity of the cover system on Dysons Open Cut;

• Long term integrity of other rehabilitation works on site; and

• Original objectives of the rehabilitation program.

Stage 2: Mechanisms of diebackTo examine the mechanisms by which dieback has occurred, such as:

• Extent to which an upward rise of contaminants has contributed to dieback;

• Mechanisms by which this occurs; and

• Extent to which the absence of Zone 2A material has contributed to dieback.


Stage 3: Remedial optionsTo recommend options for remediation which correlate with the extent of the impacts

identified in the first stage of the investigation, consider the relative costs associated

with these options, and suggest methods for monitoring the effectiveness of remedial

works.

This report summarises the results from site inspections and sampling conducted

over the period 4 to 7 June, 1997. The investigation consisted of a far more intensive

and appropriate sampling of the site than had previously been conducted and

allowed a more accurate interpretation of the causes of the vegetation dieback.

Recommendations for the implementation of remedial strategies and procedures for

assessing the success of those strategies, with respect to ensuring a sustainable

and maintenance-free vegetative cover, are presented.

5.4. METHODS

To generate the appropriate level of quantitative data to confidently explain and

interpret the current dieback, and any future expansion of the problem, the program

involved assessing the status of the vegetation in relation to:

• Depths of the three cover layers;

• Chemical characteristics of the three cover layers; and

• Physical characteristics of the three cover layers.

Field Sampling

On the basis of a preliminary visual inspection of Dysons Open Cut and the bare

area on Whites Dump, a series of soil and vegetation sampling strategies was

employed:

1. Paired sampling of bare and vegetated areas on Dysons Open Cut (9 bare, 6

vegetated);

2. Transect sampling across the bare soil / vegetation interface (2 transects);

3. Sampling of soil within the recently constructed contour banks on Dysons Open

Cut; and

4. Paired sampling of bare and vegetated areas on Whites Dump (2 bare, 1

vegetated).


These strategies aimed to provide data to permit:

• A general assessment of the causes of plant death;

• An assessment of whether a stable state had been reached or if further

expansion of the bare areas could be expected;

• Information on the effect of placing an additional layer of clean soil over the bare

areas; and

• Determination of the implications of the rehabilitation failure on Dysons Open Cut

on other areas.

Soil samples were taken in depth increments from auger holes. Sample increments

were generally 10 cm in the Erosion Resistant Layer (Zone 2A) and the Moisture

Retention Layer (Zone 1B) and 20 cm in the Moisture Barrier (Zone 1A). However,

these depth increments were varied to accommodate profile boundaries and other

morphological features. All sample holes were taken through to the underlying waste

material, and the total depth of soil capping recorded. The upper surface of the

waste was also sampled from selected holes. The approximate locations of the

major core sampling areas on Dysons Open Cut are indicated in Figure 5.2.

Figure 5.2 Approximate location of coring positions on Dysons Open Cut

Transect samplings were made across two bare / vegetation interfaces. One hole

was located at the interface within affected vegetation (see Plate1), and additional

holes were placed at 3 m spacings along a straight line placed perpendicular to the

bare / vegetation interface.


Vegetation from an area of 0.25 m2 (0.5 m x 0.5 m) was sampled along the bare/

vegetation interfaces of the two transects, at a distance of 1 m either side of the

profile hole. Additional samplings were undertaken at the 3 m and 6 m distances in

from the interface, again at 1 m distances from the profile holes and parallel to the

bare / vegetation interface. Further plant material associated with sample holes RJ7

and RJ8 was collected from locations some distance from dieback areas. On Whites

Dump, the grass was also sampled near the vegetated site profile which was 3 m in

from the bare / vegetation interface.

Plate 5.1 The interface between bare and vegetated areas along Transect 2

Laboratory analysis

Soil samples were air dried and sieved (2 mm) to separate the fine earth and coarse

fractions, and the proportion by weight of these fractions was recorded (Table 5.1).

The fine earth fraction was analysed for pH and electrical conductivity (EC) in 1:5

soil: deionised water suspensions. These suspensions were then centrifuged and the

supernatant analysed for aluminium, calcium, copper, cobalt, potassium,

magnesium, manganese, nickel, and zinc by inductively coupled plasma atomic

emission spectroscopy (ICPAES). Samples were also extracted with DTPA (Lindsay

and Norvell 1978) and analysed for copper, cobalt, chromium, nickel and zinc. For

both deionised water and DTPA extracts, the suite of analites were selected on the


basis of a preliminary spectral scan of a broad range of elements (silver, aluminium,

arsenic, gold, boron, barium, calcium, cadmium, cobalt, chromium, copper, iron,

potassium, lithium, magnesium, molybdenum, sodium, nickel, lead, sulfur, selenium,

silicon, titanium, uranium, vanadium). The elements selected for further analyses

were those of biological importance (and for which the extraction was appropriate)

which were found to be present at elevated levels.

Soil solution was extracted by centrifuge drainage (Gillman 1976) from surface soil

samples (0–15 cm) of Transect 2. Air-dry soil was rewet to field capacity (10 kPa)

and allowed to equilibrate for four days. The soil solution was extracted by

centrifugation at 2000 g relative centrifugal force for 40 min and the pH and EC were

determined immediately on 0.22 µm filtered solution. Further filtration to 0.025 µm

(Menzies et al. 1991) was then performed prior to elemental analysis by ICPAES.

Solution pH and elemental concentrations were used as inputs to the computer

speciation program GEOCHEM (Sposito and Mattigod 1980). All sulfur present in

solution was assumed to be SO4 and all potassium assumed to be PO4. Calculations

were performed at a specified ionic strength calculated for each solution from the EC

using the equation of Menzies and Bell (1988). Thermodynamic constants used for

aluminium were the selected constants of Nordstrom and May (1989). All other

constants were those included in the GEOCHEM PC Ver 2 database (Parker et al.

1991); these constants were mainly derived from published compilations (Martell and

Smith 1976-1989, Baes and Mesmer 1976, Lindsay 1979).

The underlying waste samples were analysed for pH, EC and water-extractable

aluminium, calcium, copper, iron, potassium, magnesium, sodium and zinc by

ICPAES. The potential of the samples to generate further acidity was assessed

using the net acid generation (NAG) test (Miller and Jeffery 1995).

Vegetation samples were oven-dried at 80oC for 48 h, weighed and ground.

Subsamples were digested using a 5:1 nitric acid / perchloric acid mixture and

analysed for phosphorous, potassium, calcium, magnesium, sodium, aluminium,

sulphur, iron, manganese, zinc, copper and boron by ICPAES. The samples were

also scanned for arsenic, barium, cadmium, cobalt chromium, nickel, lead, antimony


and tin. Of these latter elements, only nickel, cobalt and barium showed significant

quantities. Nitrogen was measured on a LECO combustion analyser.

5.5. RESULTS AND DISCUSSION

Cause of plant death

A visual inspection of the bare areas on Dysons Open Cut revealed salt

efflorescence at many points (Plate 5.2). A simple barium test identified this as an

accumulation of sulfate salts, and hence indicated that the soil in these areas may

have been contaminated and acidified by the copper Heap leach waste material

underlying the soil capping. Acidification of the bare areas was confirmed by the

laboratory analysis (Tables 5.1, 5.2 and 5.3). The mean pH of 4.60 found in the 0–10

cm soil samples taken from bare areas is sufficiently acidic for aluminium toxicity to

be a limitation to plant growth (Menzies et al. 1994), and is significantly (P<0.001)

lower than that found in the surface of vegetated areas (pH 5.69).

The solubility of aluminium and manganese increases as pH decreases, Al3+ activity

increasing 1000 fold, and Mn2+ activity increasing 100-fold for each pH unit

decrease. At pH values below about 5, the levels of aluminium in soil solution

become sufficiently high to limit plant growth. While accurate prediction of aluminium

toxicity is dependent on the determination of soil solution Al3+ activity, a cruder

assessment can be made on the basis of aluminium concentration. Toxicity has

been reported for sensitive species at soil solution aluminium concentrations > 200

µM for soybean (Evans and Kamprath 1970) and for relatively tolerant species such

as maize at aluminium concentrations > 400 µM (Evans and Kamprath 1970, Friesen

et al. 1980). These values are greatly exceeded by the concentrations present in the

1:5 soil:deionised water extracts analysed (Table 5.2).


Plate 5.2 Salt efflorescence at the surface of a dieback area

Use of soil solution aluminium activity, determined by thermodynamic calculations,

provides a more sensitive assessment of the potential for aluminium phytotoxicity.

Speciation calculations determined the proportions of aluminium present in solution

as free Al3+, as aluminium associated with hydroxyls (OH) and as ion pairs with

ligands such as SO4. Such speciation is important as not all forms of aluminium in

solution are phytotoxic; Al3+ is considered toxic, while Al-SO4 ion pairs are non-toxic

(or less toxic) (Cameron et al. 1986, Kinraide 1991). As the SO4 concentrations in

these soils are high, much of the aluminium in solution is present as Al-SO4 ion pairs;

92% in Hole 1 and 87% in Hole 2 of Transect 2 (Table 5.4). The activity of Al3+ in

these two samples taken from bare areas was < 1 µM, and would be toxic to only the

most aluminium sensitive species, while the Al3+ activity in soil solution from the

vegetation interface was < 0.1 µM and thus non-phytotoxic (Table 5.4). Critical Al3+

activities for toxicity are typically < 10 µM (eg. subterranean clover 3 µM, Wright and

Wright 1987; soybean 4µM, Bruce et al.1988; mungbean 2 µM, Menzies et al. 1994)

(note: higher critical activities are reported in earlier studies where all aluminium was

considered to be present as Al3+.) Thus, aluminium may present a limitation to plant

growth on the acidic bare areas, but is not present at toxic levels in the soil at the

vegetation interface and hence is not responsible for the dieback.


In highly weathered soils, aluminium activity has generally been controlled by the

dissolution of gibbsite (Richburg and Adams 1970, Marion et al. 1976, Bruce et al.

1988, Manson and Fey 1989, Menzies et al. 1994). In contrast, Al3+ activity in this

study was consistently lower than that which would have been supported by the

dissolution of gibbsite. For example, the solubility of gibbsite would maintain an Al3+

activity of 12 µM at soil solution pH of 4.32 found in Transect 2, Hole 1, but an Al3+

activity of 1.08 µM was determined for this solution. The Al3+ activities determined in

this study agree well with those expected if the soil solution Al3+ activity was being

controlled by dissolution/precipitation of the Al-SO4 minerals alunite or jurbanite.

These minerals are more stable than gibbsite at pH values of below 5.5 to 6.0

depending on SO42- activity. Such minerals have been considered in studies of

acidification from atmospheric acid deposition (Nordstrom and Ball 1986, Reuss and

Johnson 1986, Khanna et al. 1987) and in studies of acid sulfate soils and

rehabilitated site wastes (Kittrick et al. 1982, Karathanasis et al. 1988). Solubility

control by these minerals results in low and non-phytotoxic aluminium levels despite

the low soil pH.

The concentration of manganese in the 1:5 soil: deionised water extracts are lower

than those considered phytotoxic (Morris 1948, Adams and Wear 1957,Sonneveld et

al. 1977) (Appendix A.2). This view is further supported by the moderate DTPA-

extractable manganese contents Appendix A.5) which seldom exceed 100 mg kg-1;

Rayment and Verrall (1980) reporting that concentrations below 400 mg kg-1 should

not affect kikuyu grass.

Copper was found at high concentrations in both water and DTPA extractions. While

copper is recognised as a plant nutrient, it is also toxic at elevated levels (Hart 1974).

Unfortunately, no clear criteria for assessment of copper availability in soils has been

developed. Solution culture studies have shown yield depression in a range of crop

species from concentrations of < 200 µM and that lethal concentrations are generally

< 3000 µM (Davis and Beckett 1978). These values are clearly exceeded in many of

the water extractions (Appendix A.2), and in the soil solutions from the bare areas

and vegetation interface (Appendix A.3).


The chelating agent DTPA has been widely used to assess metal availability (Risser

and Baker 1990). This compound reacts with metal in soil solution and also

combines with adsorbed metal if the stability of the DTPA-metal complex is greater

than the stability of the soil-metal complex (Lindsay and Norvell 1978). Plenderleith

(1984) reported that dry matter yield of buffel grass was decreased by 50% at a

DTPA-extractable copper concentration of 80 mg kg-1, and that 100 mg kg-1 was

lethal on a sandy loam soil. Bell (1986) reported >75% yield reduction for Rhodes

grass and sabi grass at 250 mg kg-1 in a podzolic soil, but in a clay soil > 600 mg kg-1

was needed to produce the same yield reduction. Thus, the DTPA method is

generally a poor predictor of copper toxicity, with critical concentrations increasing

with soil clay content. While the principal use of DTPA extraction in this study was to

permit analysis of metal movement in the profile, the low clay content of the upper

layers of the soil capping and the high DTPA-extractable copper concentrations

present (Appendix A.5) also meant that the extractant in this situation was able to

provide an unambiguous prediction of copper toxicity. This was further supported by

plant tissue analysis (Appendix A.6).

Potential for dieback expansion

It is apparent from the pH and copper concentration data that plant death has been

caused by capillary movement of acidic, metal-contaminated solution from the

underlying copper Heap leach waste material into the covering soil layers. A key

question is whether this process will lead to further expansion of the bare areas. The

data obtained from sampling the two transects (Figures 5.3 and 5.4, Appendix A.7

and A.8) indicates that rise of acidity and metal has been similar across the transect.

Contamination of the surface soil, and resultant plant death, has occurred most

rapidly where the depth of soil is smallest. With increasing time since rehabilitation,

areas with an increasingly greater depth of soil are degrading. Therefore, the

interface areas where copper toxicity causes plant death during the growing season

is expected to move progressively into the vegetated portion of the surface thus

increasing the bare areas (Plate 5.3). This gradual expansion of the degraded area

is clearly demonstrated in aerial photography of the site taken over time.


Figure 5.3 Diagrammatic representation of the pH distribution within the soil capping atTransect 2.

Individual data points are the pH value of the depth increment sample for soil cores taken at fivelocations. Isopleths for pH are superimposed at 0.5 pH unit inc

Figure 5.4 Diagrammatic representation of the DTPA-extractable Cu distribution within thesoil capping at Transect 2.

Individual data points are the Cu concentration of the depth increment sample for soil cores taken atfive locations. Isopleths for Cu concentration are superimposed at the 0mg kg-1 and 250 mg kg-1

levels. The soil/waste interface is indicated by the dotted line.


Plate 5.3 An area of expanding dieback along the northern edge of Dysons Open Cut

With loss of vegetation from an area, water exploitation from the soil profile by the

plant will cease. Thus water loss will principally occur through deep drainage and

through evaporation from the soil surface. Lateral flow through the upper layers of

the soil profile may be significant on this site, but represents a redistribution of water

and mechanism for further spread of contamination rather than a water loss

mechanism. The change from water loss by evapotranspiration to capillary rise and

evaporation from the soil surface would be expected to increase the rate of

contaminant movement to the surface.

The underlying waste material still contains unoxidised sulfidic material, as

demonstrated by the NAG pH data (Appendix A.9). It should be noted that the waste

material sampled and tested was the uppermost surface of the waste, and hence

has had the greatest exposure to oxygen. Waste material deeper within the pit could

be expected to be less oxidised and hence have an even greater potential to

produce further acidity.

It is considered that the observed differences in depth of soil cover result from

uneven spreading during the capping operation. Thus the difference in soil depth is


the cause of plant death, rather than the result of erosion following loss of

vegetation. This view is based on the relatively constant proportion of fine soil

fraction in surface soil samples taken from bare and vegetated areas (Appendix A.1).

The mean value for vegetated areas (38%) was not significantly different from that of

the bare areas (41%) (P<0.01), and is within the range specified for the Erosion

Resistant Zone (Zone 2A) material (25-60% <2.36 mm) in the Rum Jungle

Rehabilitation Project: Final Project Report (Allen and Verhoeven, 1986). The nature

of the Zone 2A material is such that on exposure to rainfall, the fine material is

washed from the immediate surface (Plate 5.4) leaving the coarse fraction which

forms an armoured, erosion resistant capping.

Plate 5.4 Surface fines collecting on the upslope of the recently added contour banks

On the basis of the findings detailed, further expansion of the bare areas is

anticipated. The final extent of degradation will be determined by the distribution of

the copper Heap leach waste.

An indication of the effect of placing additional soil over the contaminated areas can

be gained from examination of the fresh soil placed in the new contour banks

constructed on the upper portion of the revegetated area. Movement of contaminants

from the old soil surface into the fresh soil is demonstrated by the elevated

concentrations of Cu, nickel and cobalt in the DTPA extracts, and by the elevated EC


and lowered pH of the lower 15 cm of the contour bank (Appendix A.10, A.11).

These laboratory results support a field observation that grass roots only penetrated

to within 5 cm of the old soil surface. On the basis of these results, we do not

consider that placement of additional soil to increase the thickness of the capping

layer would be an effective means of obtaining a stable vegetation cover. Increasing

the soil thickness would simply delay acidification and accumulation of toxic

concentrations of copper at the soil surface, by a number of years.

Implications for other dumps

Deterioration of the rehabilitated surface on Dysons Open Cut is clearly the result of

contaminant movement from the underlying copper Heap leach waste, and is thus

considered to be a problem unique to this area of the Rum Jungle rehabilitation.

The smaller bare area on Whites Dump (Plate 5.5) appears to be the result of

inadequate soil cover (2–5 cm). While the underlying waste rock is acidic and has

the capacity to generate further acidity (Appendix A 9), it does not represent a

copper contamination source (Appendix A.12, A.13). Where acidification of the cover

system did occur, it was restricted to the bottom 5–10 cm of the soil. Given the

coarse nature of the material constituting the waste rock dumps, little capillary

movement, relative to that from the clay copper Heap leach material, would be

expected. The limited acidification of the cover observed on the waste rock dumps

may, in fact, be beneficial. If aluminium toxic, this layer would prevent root

penetration of the clay seal eliminating the need for regular slashing of the site to

prevent tree growth.


Plate 5.5 Looking towards the only significant area of dieback on Whites Dump

5.6. REMEDIATION OPTIONS

The final option chosen will be determined by principles that are established for

monitoring and maintaining vacant Crown Land.

1. Do nothing

This assumes that the surface cover will remain intact, ie. resist erosion, so that the

clay seal limiting water and oxygen entry is not totally breached and exposes the

underlying waste. Clearly the erosion resistance of the capping would need to be

established by monitoring of erosion loss of soil (by installing both trenches to collect

downslope movement and flow sampling in the drain would be required). The other

question to be addressed here is: What output of copper is going to occur by doing

nothing? If samplers were installed to measure particulate load in runoff, it would be

recommended to also determine metal content in the runoff.

The do nothing approach does mean that the input of water into the pit would be

expected to be greater (due to no transpiration demand), so the volume of acid

drainage would be increased. Clearly the drainage water that does emerge from

Dysons Open Cut is acid (Plate 5.6), and would no doubt have a high copper load.

Therefore, an increased input to the pit would result in an increased copper load out.


If further increases in copper in the drainage are not acceptable then clearly neither

is doing nothing about the further degradation of the vegetated surface.

The cost of this option is that involved with erosion monitoring and drainage

sampling.

Plate 5.6 Acid waters at the exit point of the drainage from Dysons Open Cut

2. Cover with rock mulch

This approach would need to be considered subject to the finding that there was too

high an erosion rate from the bare surface. It would still have the problem of

increased infiltration into the pit. In fact, infiltration would most likely be even higher

than from the bare surface as the rock mulch would reduce evaporation. The rate

and volume of runoff would be reduced by the mulch acting to slow water movement

across the surface, but if the subsurface lateral drainage increased, the copper load

out of the pit will continue and increase.

The cost of this option will be a contractor’s price for the supply and distribution of a

suitable rock cover over the area. The option will not result in a vegetated landscape

but will reduce the risk of massive failure and exposure of the contaminated waste.


3. Install a capillary break layer and replace soil cover layers

Evidence suggests that simply increasing the depth of soil capping alone is not a

long-term solution, and thus the installation of a proper capillary break and re-

establishment of a root zone is the least risk option. However, it is clearly the most

expensive of the options. As part of this exercise, the problem of subsidence

producing a low spot in the drainage system could be corrected. Considering the

cost of this option, the area which needed to be treated would need to be carefully

assessed. Only those areas of the pit covered with copper Heap leach material

would be expected to suffer from dieback. This may not be the whole pit surface.

This information could be available from construction records; otherwise a pattern of

test augering across the entire pit surface would be warranted.

The cost of this option will be driven initially by the extent of the copper Heap leach

material that is buried beneath the existing inappropriate cover. Thereafter, costs for

reconstruction of an effective capping can be calculated.


6. EFFECTIVENESS OF COVERS ON THE OVERBURDEN HEAPSG P TIMMS AND J W BENNETT

ANSTO Environment, Lucas Heights

6.1. INTRODUCTION

Following recommendations made by Bennett in the 1988-93 Rum Jungle Monitoring

Report (Kraatz 1998), further monitoring was carried out on the overburden heaps

from 1993 to 1998. The principal aim of this work was to quantify pyrite oxidation and

water infiltration rates post-rehabilitation and hence enable the effectiveness of the

rehabilitation works on the overburden heaps to be quantified.

Two parameters were considered in quantifying the effectiveness of the covers on

the overburden heaps. The first was the rate at which pollutants were generated

within the heaps. Oxidation of pyrite has previously been found to be the primary

pollutant generation mechanism (Davy 1975), and the rate of pyrite oxidation can, in

some circumstances, be estimated from measurements of oxygen concentration

profiles in the heaps. As the pyrite oxidation reaction is exothermic, the rate may also

be estimated from heat source distributions (calculated from measured temperature

profiles). The second important parameter was the water flux (or infiltration rate)

which influenced the rate at which pollutants were transported from the heap. The

infiltration rate was directly measured using lysimeters.

Measurements of oxygen concentration and temperature are presented for the three

heaps, along with calculated oxidation rates before and after rehabilitation. In the

case of Dysons heap the rates could not be estimated but some general conclusions

could be drawn. Measurements of the infiltration rate into Whites heap are also

presented.


6.2. INSTRUMENTATION OF OVERBURDEN HEAPS

Whites and Intermediate heaps

Infiltration rates were monitored using lysimeters, which had been installed in Whites

and Intermediate heaps before placement of the clay layer, as described by Bennett

et al. (1989). Ten lysimeters were installed in Whites heap and eight in Intermediate

heap, two at each of the locations shown in Figure 6.1.

CA

B

DE

1 23

4

White’s dump

Intermediate dump

Figure 6.1 Lysimeter positions on Whites and Intermediate overburden heaps. Twolysimeters are located at each position marked by a triangle

The two heaps were also instrumented with probe holes for measuring pore gas

concentrations and temperatures. Initially, six holes were drilled in Whites heap in

September 1976 to enable temperatures to be measured. Before rehabilitation

commenced in 1982, a further three holes were drilled in Whites heap and fifteen

holes were drilled in Intermediate heap. These older holes are designated

alphabetically. While the older probe holes on Whites are still useable, those on


Intermediate were destroyed during the reshaping of the dump surface, prior to cover

emplacement. Intermediate heap was re-instrumented with twenty-one probe holes

of a slightly different design (I01R to I21R) in 1985 and ten additional probe holes

(W10R to W19R) were installed in Whites heap in 1987.

These probe holes enabled oxygen concentration and temperature profiles to be

measured. This data provided information about gas and heat transport processes

within the heaps and, in some circumstances allowed the overall oxidation rate (and

overall pollutant generation rate) within the heaps to be quantified. The locations of

the probe holes on Whites and Intermediate heaps are shown in Figure 6.2. The

layout of a typical post-rehabilitation probe hole is shown in Figure 6.3. The holes

were backfilled so that the openings of the oxygen tubes were in a layer of gravel,

with sand and bentonite layers separating the tube openings from those above and

below. There were two nylon tubes extending to each depth for the extraction of pore

gas samples. This arrangement also allowed air permeability and gas diffusion

measurements to be made.

10

17

A11

1218B

13

19D

14

C

16

E

15 F

100mpos t-rehabilitation

DIVERSION CHANNEL

DR

AIN

pos t-rehabilitation

DIVERSION CHANNELDRAIN

EROSION B

ANK

N

13

1014

16

19

1720 21

18

15

121

465

2 37

89

50 m

N

Figure 6.2 Location of probe holes used to monitor temperature and pore gas concentrationprofiles in Intermediate (left) and Whites (right) heaps.

Note the difference in scale.


Dysons heap

A recommendation of the 1988-1993 Rum Jungle Monitoring Report (Kraatz 1998)

was that if Dysons Overburden Heap was believed to be a significant pollution

source, then measurements should be made to quantify oxidation and pollutant

generation rates in the heap. These measurements were then to be related to

measurements of groundwater pollution loads from the heap.

Metal (copper, manganese and zinc) loads from Dysons Overburden Heap as well

as total metal loads from the site were determined for the 1973/4 wet season and

presented in Rum Jungle Environmental Studies (Davy 1975). The copper and zinc

loads from Dysons heap were very small (about 200 kilograms each) when

compared with the total copper and zinc loads from the site (130 t copper and 40 t

zinc). While the manganese load from Dysons was higher (5 t), this still represented

only 5% of the total from the site. Sulfate loads from Dysons were not estimated.

dust cap

schrader valve

bentonite plug

165 mmdiameter drilledhole

thermistor

thermistor string

sand backfill

32 mm outsidediameter PVC pipe

water tightcap

thermistor string plug

dump surface

4.76 mm outsidediameter nylon tube

gravel backfill

bentonite

Figure 6.3 Layout of post-rehabilitation probe holes installed at Rum Jungle


Post-rehabilitation data (Kraatz and Applegate 1992:51) indicated that 23% of the

sulfate load from the site originated in the Dysons rehabilitation area. Both the

sulfate concentrations and flow volumes from the open cut were comparable or lower

than those found in the springs on Dysons Overburden Heap in the previous year’s

data (pp33-36). Therefore it seemed probable that between 10 and 15% of the total

sulfate load from the site originated from Dysons Overburden Heap . Hence, while

Dysons Overburden Heap was not a significant pollution source with regards to

metals, it appeared that the heap was responsible for a relatively large percentage of

the total sulfate load from the site.

A further reason to commence monitoring of Dysons heap was the difference in the

cover design used on that heap. The slope of the batters was not altered and the

cover was only placed on the top surface while the batters remained uncovered. It

was felt that the effectiveness of this cheaper scheme would be of interest to the

mining industry.

For these reasons, it was decided to instrument Dysons Overburden Heap with a

total of twelve probe holes for the measurement of pore gas concentration and

temperature. These probe holes were installed between 30 October and 8 November

1995. The liners and backfill were identical to those on Intermediate and Whites

heap. Figure 6.4 shows the location of the probe holes on Dysons heap.


D06R

D12R

D11R

D07RD02R

D03R

D08R

D10R

D09R

D01R

D05R

D04R

70

78

85807773

8382

81

8079

87

8685

84

90

89

88

N

DROPSTRUCTURE

DYSON’S DRAIN

DYSONS OVERBURDEN HEAP AFTERCOMPLETION OF REHABILITATION

0metres 50 100 metres50

Scale - 1:2500 (approx)Contour Drains

Figure 6.4 Location of probe holes on Dysons heap

6.3. METHODS

Infiltration rates

The design of the lysimeters installed at Rum Jungle has been discussed previously

(Bennett et al 1989).

On a regular basis, the water level inside each lysimeter was returned to a reference

level. During the wet season, this generally involved pumping out a volume of water

while in the dry, water had to be added. Water losses during the dry season were a

result of wicking (capillary action and vapour transport that removed water from the

lysimeter). The measured volumes were added over a yearly period, corrected for

wicking and then expressed as a percentage of incident rainfall.


Wicking rates were measured from 1985 to 1988 and from 1996 to 1998 during the

dry season. When measured, the wicking correction was applied to the wet season

immediately following the measurement. When not measured, an average value was

used to correct the measured infiltration rates for wicking.

The lysimeters on Whites heap were reset at a reference level in November 1994.

Measurements were made at approximately three-monthly intervals until September

1996 and then monthly until December 1998.

Measurements on Intermediate heap were discontinued in May 1991, by which time

the number of operational lysimeters on the heap were felt to be insufficient to

provide representative data (see p53 of Kraatz 1998).

Temperature measurements

Temperatures were measured as a function of depth using thermistors, accurate to ±

0.1°C, which were lowered down the probe hole liners. Measurements were made in

Whites and Intermediate in June of 1993, 1996, 1997 and 1998, to monitor cooling of

the interior of the heaps as a function of time.

Measurements were made in Dysons heap in June of 1996, 1997 and 1998. Along

the main axis (D06R to D10R) measurements were also made in July, September,

October and December of 1998. The purpose of the latter measurements was to

obtain information about the seasonal dependence of the temperature profiles in

Dysons heap.

Oxygen concentration measurements

Pore gas samples were taken at various depths via the 4.76 mm outside diameter

nylon tubes shown in Figure 6.3 and the oxygen concentration of the samples

determined using ANSTO’s Automatic Oxygen Analyser. This instrument was

software controlled and incorporated an electric pump to draw up pore gas samples

through the nylon tubes, solenoid valves to switch between the tubes and a


Teledyne oxygen fuel cell to determine the oxygen concentration in the samples (to

an accuracy of 0.05 vol %).

Measurements were carried out on Whites and Intermediate heaps in June 1993, at

three monthly intervals from November 1994 to September 1996 and then monthly to

December 1998. Measurements commenced on Dysons in November 1995 and

were carried out at three monthly intervals.

In the past, diurnal air pressure variations have affected the oxygen distribution in

the heaps (Kraatz 1998). To ensure that representative oxygen concentrations were

obtained measurements on Intermediate and Dysons were made in the morning

(maximum in atmospheric pressure) and repeated in the afternoon (minimum in

atmospheric pressure). The measurements on Whites heap were repeated every 2

hours over a 24-hour period.

Calculation of oxidation rates

• From oxygen concentration profiles

There are a number of processes which can transport oxygen through the pore

space of an overburden heap to oxidation sites. One process, diffusion, results from

differences in oxygen concentration in different parts of the heap. A second process,

advection, is caused by differences in total gas pressure in different parts of the

heap. Convection is a special case of advection where the pressure difference is

caused by differences in gas temperature.

The shape of the oxygen concentration profiles enables the dominant oxygen

transport mechanism to be determined. A monotonic decrease in oxygen

concentration with depth indicates that diffusion is the dominant transport

mechanism while profiles fluctuating in time or space generally indicate that

advection (including convection) is a significant transport mechanism.

For a case where diffusion is the dominant oxygen transport mechanism, the

constant rate model (Gibson et al. 1994) can be used to estimate the intrinsic


oxidation rate (IOR) of the material as well as the overall oxidation rate of the heap

(the IOR is the rate of oxygen consumption within a volume of one cubic metre). The

constant rate model assumes that as long as oxygen and pyrite are present at a

location, oxidation will occur at a constant rate (independent of the oxygen and pyrite

concentrations). Once either concentration falls to zero, oxidation ceases.

Experiments (Hammack and Watzlaf 1990, Bennett and Gibson 1992, Strömberg

1997) have indicated that the oxidation rate in bulk samples of waste rock exhibits a

square root or Monod dependence on oxygen concentration, so such an

approximation is reasonable.

The model involves solving the steady state diffusion equation in one dimension and

assuming that the IOR and diffusion coefficients are independent of depth. Under

these conditions we obtain

for the IOR, S, in kg (O2) m-3 s-1. D is the diffusion coefficient of oxygen in waste rock

in m2 s-1, Ct is the oxygen concentration at the top of the oxidation layer in kg(O2) m-3

and X1 is the depth of the oxidation layer in metres. Ct and X1 can be determined the

measured oxygen profile and hence the ratio S / D is readily determined. The overall

or global oxidation rate (GOR) at the given location is then simply a product of the

IOR and the oxidation layer depth.

In determining Ct it is necessary to locate the top of the oxidation layer. At early

times (typically the first 50 or 100 years), the top of the oxidation layer is located at

the surface for an uncovered waste rock dump and at the base of the cover in a

covered dump. At Rum Jungle, this is expected to still be the case. If this surface

region had fully oxidised, the top of the oxidation layer could still be identified through

a change in the profile from a linear to nonlinear decrease in oxygen concentration

with depth.

The GOR was evaluated at each of the probe holes using this technique and an

estimate of the overall rate of oxidation within each dump was then made.

21

2XCD

S t= (1)

1

2GOR

XCD t= (2)


• From temperature profiles

Elevated temperatures are commonly found within overburden heaps. These

temperatures can be used to obtain a distribution of heat sources throughout the

heap. The heat source strengths can easily be converted to oxidation rates as in the

pyrite oxidation reaction 1.29 × 107 joules of heat are generated for each kilogram of

oxygen consumed.

Once a dump has been covered, temperatures are expected to fall (as the

magnitude of the heat sources decreases). Using a model of heat conduction within

the dump, an upper limit can be obtained for any heat sources remaining within the

dump.

It should be noted that this technique is more successful when applied to heat

sources at depth, which cause significant heating of the interior of the dump and are

relatively easy to identify. In contrast, heat emanating from sources near the surface

can be transported away by radiation and convection and does not necessarily lead

to a large temperature rise within the waste rock.

Oxygen diffusion coefficient of the cover

If we assume that the cover does not consume oxygen, we can use the constant rate

model to derive an expression for the effective diffusion coefficient of the cover

material,

where Ct is the oxygen concentration at the top of the oxidising zone, assumed here

to be the base of the cover.

Equation (3) was used to calculate the effective diffusion coefficient of the cover at

each of the probe hole locations on Intermediate and Whites heaps.

While the above analysis assumes that no oxygen consumption occurs in the cover,

it should be noted that oxygen consumption in the cover has little effect on the

( )ttc

c CCSDCx

D−

=0

2

(3)


effective diffusion coefficient as long as the IOR of the cover material, Sc, obeys the

relation

A typical value for the IOR of soil is 5 × 10-8 kg (O2) m-3 s-1 (Baver et al 1972) and xc

is approximately 0.6 m for the Rum Jungle covers. Hence oxygen consumption in the

cover can be assumed insignificant at Rum Jungle if Dc is much greater than 1.8 ×

10-8 m2 s-1.

6.4. RESULTS

Infiltration rates

The measured infiltration, measured wicking and the calculated total infiltration for

Whites heap are shown in Table 6.1 for each year over the entire monitoring period.

Data was collected from all ten lysimeters throughout the measurement period with

the exception of the 1991/92 and 1992/93 wet seasons, when only nine lysimeters

were functioning.

Table 6.1 Post-rehabilitation measured infiltration, wicking and calculated total infiltrationfor Whites heap (*not measured during preceding dry season, average loss/ weekused)

Period Rainfall (mm) MeasuredInfiltration (mm)

Wicking (mm) Total Infiltration(%of Rainfall)

Nov 84 – May 85 1072 16.0 7.9* 2.2May 85 – May 86 1087 12.8 10.6 2.2May 86 – Jun 87 1289 19.8 15.9* 2.8Jun 87 – Jun 88 1057 7.9 7.7 1.5Jun 88 – Aug 89 1625 39.4 16.9* 3.5Aug 89 – Oct 90 1008 7.3 17.8* 2.5Oct 90 – May 91 1587 52.2 9.7* 3.9May 91 – May 92 1008 10.0 16.2* 2.6May 92 – Jun 93 1421 20.7 15.8* 2.6Nov 94 – Jun 95 1484 80.7 8.7* 6.0Jun 95 – Jun 96 998 71.2 15.6* 8.7Jun 96 – Jun 97 1763 164.0 15.2* 10.2Jun 97 – Jun 98 1821 77.4 14.9 5.1

12

<<c

cc

DxS

(4)



Temperature contours are plotted on cross-sections through Whites, Intermediate

and Dysons heap in Figure B.1 to B.5 of Appendix B as a function of time. Cross-

sections were selected which passed through those regions of Whites and

Intermediate dumps that contained greatly elevated temperatures at the

commencement of monitoring.

Oxygen concentration measurements

Oxygen concentration contours are plotted on cross-sections through Whites,

Intermediate and Dysons heaps in Figures B.6 to B.16 of Appendix B as a function of

time.

To determine the global oxidation rate at each measurement location using Equation

(2), measurements of the oxygen concentrations at the base of the cover are

needed. The measured oxygen concentrations at the base of the cover are shown as

a function of time in Tables 6.2 and 6.3 for Whites and Intermediate heaps

respectively. These values were obtained by averaging over all measurements

carried out at each of the probe holes over a three-year period. The quoted error is

the standard error of the mean.

Table 6.2 Oxygen concentration (in vol%) at the base of the cover on Whites heap

YearsRegion Probe Hole 1988-90 1991-93 1994-96 1997-

Average overtime

W10R 7.8 6.2 4.2 6.3 5.7A

W11R 4.0 9.0 9.2 10.1 8.8

W12R 9.6 12.3 13.2 13.9 12.9

W13R 13.2 13.7 18.2 18.0 16.9

W14R 11.7 11.3 9.4 13.0 11.3

W17R 17.7 18.7 16.5 19.6 17.8

B

W18R 1.8 7.2 8.2 10.9 7.1C W16R 15.9 19.6 18.3 18.0 18.0D W19R 11.9 13.1 14.0 - 12.7

E/F W15R 9.0 13.6 12.8 13.5 12.7

Average over space 10.2 ± 0.6 12.5 ± 0.5 12.4 ± 0.4 13.7 ± 0.3 12.4


The average over time in both tables is skewed towards the recent, more frequent

measurements.

The data for both heaps were split into measurements taken during the dry season

(June-October) and the wet season (December-April). The average oxygen

concentration at the base of the cover for these seasons is shown in Table 6.4. The

standard error of the mean is shown for each set of measurements.

Table 6.3 Oxygen concentrations (in vol%) at the base of the cover on Intermediate heap

Years

Probe Hole 1985-87 1988-90 1991-93 1994-96 1997-Averageover time

I01R 10.3 16.3 14.6 14.7 17.7 14.2I02R 8.0 10.1 11.7 12.9 12.4 11.7I03R 8.8 13.5 15.6 14.6 18.3 13.9I04R 5.7 8.8 9.0 12.2 12.7 9.4I05R 3.3 2.7 8.7 7.7 10.2 7.5I06R 3.8 5.2 2.3 9.0 - 5.1I07R 8.2 11.2 15.2 19.1 14.8 12.2I10R 6.8 6.9 8.4 11.4 16.2 9.7I11R 7.0 7.4 10.9 10.6 11.0 9.8I12R 2.6 3.9 4.1 7.9 8.4 5.5I13R 3.5 7.9 9.4 11.0 14.8 9.2I14R 6.0 9.2 10.1 0.2 0.5 3.1I15R 6.7 6.0 6.7 19.1 18.1 11.3I16R 11.3 9.4 14.0 16.4 15.5 14.1I17R 11.3 12.0 13.6 14.8 16.0 13.4I18R 4.6 5.4 9.8 11.8 11.7 8.7I19R 9.4 10.2 14.8 14.1 13.7 12.9I20R 6.6 6.3 9.1 10.5 10.1 8.3I21R 5.1 5.7 9.1 16.5 19.1 11.6

Averageover space 6.8 ± 0.4 8.3 ± 0.4 10.4 ± 0.5 12.4 ± 0.4 13.4 ± 0.3 10.1


Table 6.4 Average oxygen concentration at the base of the cover in the wet and dryseasons

Average oxygen concentration at the base of the cover (vol%)

Whites Intermediate

Wet season 10.8 ± 0.3 9.4 ± 0.1

Dry season 13.6 ± 0.2 10.9 ± 0.1

Oxidation rates

The measured oxygen concentration and temperature data were used to estimate

the oxidation rates of Whites and Intermediate heaps before and after rehabilitation.

When calculating oxidation rates from oxygen concentration profiles, the oxygen

diffusion coefficient of the waste rock was assumed to be 1 × 10-6 m2 s-1 (its true

value is likely to lie somewhere between 1 × 10-6 and 4 × 10-6 m2 s-1). Choosing a

larger value of this parameter increases the overall oxidation rates, however it has

little impact on the ratio of the post- to pre-rehabilitation oxidation rates.

Whites heap

To assist with the comparison of pre- and post-rehabilitation rates, Whites heap was

divided into five regions (each region surrounding one of the pre-rehabilitation probe

holes). The estimated overall oxidation rates for each region of Whites heap prior to

rehabilitation were calculated from the temperature and oxygen profiles using the

technique described in Section 6.3. They are shown in Table 6.5.

Table 6.5 Pre-rehabilitation oxidation rates in Whites heap

GOR (kg(O2) m-2 s-1)Region Area (m2) From heat source From oxygen

profiles

Overalloxidation rate

(kg(O2) s-1)

A 37 800 5.6 × 10-7 - 0.0212B 74 700 ~0 2.7 × 10-7 0.0202C 44 200 6.0 × 10-8 - 0.0027D 50 200 7.4 × 10-8 4.4 × 10-8 0.0022

E/F 53 100 6.1 × 10-9 - 0.0003Total 260 000 - - 0.0466

NB: (GORs were estimated using the techniques described in Section 6.3)


It was not possible to estimate the GOR from the oxygen concentration profile at

probe hole A as the profile indicated that convection was a significant gas transport

mechanism and hence the technique described in section 6.3 could not be applied.

No oxygen concentration measurements were made at probe hole locations C and

E/F. Where two estimates of GOR were available at the one probe hole, that

calculated from the oxygen concentration profiles was used to estimate the overall

oxidation rate in the region. The estimate from the oxygen concentration data was

felt to be more reliable as in each of these cases oxidation was occurring near the

surface (the region in which estimates of heat source distributions from measured

temperatures were least reliable).

The pre-rehabilitation overall oxidation rate of the entire heap was 0.0466 kg (O2) s-1,

which corresponds to an overall sulfate generation rate of 0.0799 kg (SO4) s-1. This

is equivalent to an annual sulfate production of 2520 t.

The corresponding post-rehabilitation rates for each region of Whites heap are

shown in Table 6.6. The fluxes for each region were an average over all the probe

holes in that region.

Table 6.6 Post-rehabilitation oxidation rates in Whites heap

Region Area (m2) GOR (kg(O2) m-2 s-1) Overall oxidation rate(kg(O2) s-1)

A 37 800 4.42 × 10-8 0.0019B 74 700 7.05 × 10-8 0.0052C 44 200 4.59 × 10-8 0.0020D 50 200 5.74 × 10-8 0.0032

E/F 53 100 2.60 × 10-8 0.0014Total 260 000 - 0.0137

NB: (GORs were estimated using the technique described in Section 6.3)

The post-rehabilitation overall oxidation rate of the entire heap was

0.0137 kg (O2) s-1 which corresponds to an overall sulfate generation rate of

0.0235 kg (SO4) s-1 or 740 t (SO4) yr-1.

The post-rehabilitation data was grouped into three-year periods and the overall

oxidation rate plotted as a function of time (Figure 6.5).


Figure 6.5 Overall oxidation rate in Whites heap as a function of time

Intermediate heap

The estimated GORs, due to near surface oxidation, at each probe hole of

Intermediate heap prior to rehabilitation are shown in Table 6.7.

Table 6.7 Pre-rehabilitation GORs due to near surface oxidation in Intermediate heap

Probe Hole Oxidation layer depth(m)

IOR (kg(O2) m-3 s-1)

GOR(kg(O2) m-2 s-1)

Zg 1.90 1.47 × 10-7 2.79 × 10-7

K 3.15 5.34 × 10-8 1.68 × 10-7

Yg 2.70 7.27 × 10-8 1.96 × 10-7

Q 1.90 1.47 × 10-7 2.79 × 10-7

X 1.40 2.70 × 10-7 3.79 × 10-7

W 6.55 1.24 × 10-8 8.09 × 10-8

R 2.95 6.09 × 10-8 1.80 × 10-7

NB: The IOR and GOR were estimated using the technique described in Section 6.3

The average GOR was 2.33 x 10-7 kg (O2) m-2 s-1. As there was little variation in the

GOR across the measured points, it was reasonable to assume that such a GOR

was present over the entire surface of the heap and hence there was no need to

divide the heap into regions as was done with Whites heap. Therefore, the

contribution to the overall oxidation rate from near surface oxidation was 0.0161 kg

(O2) s-1.

Years

1988-90 1991-93 1994-96 1997-

Ove

rall

oxid

atio

n ra

te (k

g (O

2) s

-1)

0.010

0.011

0.012

0.013

0.014

0.015

0.016

0.017


A heat source distribution was obtained at depth in probe hole Zg using an inverse

temperature solver, enabling an estimate to be made of the oxidation rate due to the

source at depth. Using the inverse temperature solver the total heat production at

depth in the vicinity of probe hole Zg was estimated to be 3 W m-2.

An alternative estimate of the oxidation rate at depth was obtained from a heat

conduction model of the heap. This model suggested that a total heat production at

depth of 8.3 W m-2 was necessary to result in the observed temperatures. Estimating

the region in which such heat production occurs as being 70 m by 100 m (almost

certainly an overestimate), then the overall oxygen consumption rate at depth in

Intermediate dump was 1.6 x 10-3 kg (O2) s-1 by the first technique and 4.3 x 10-3 kg

(O2) s-1 by the second. These values are about a tenth and a quarter respectively of

the overall oxidation rate due to near surface oxidation. The second estimate was

preferable as the accuracy of the heat source distribution was compromised by the

sparsity of data. The components of the overall oxidation rate in Intermediate heap

before rehabilitation are shown in Table 6.8.

Table 6.8 Contribution to the overall oxidation rate in Intermediate before rehabilitation ofnear surface oxidation and oxidation at depth

Region of Heap Overall oxidation rate (kg (O2) s-1)

Near the surface 0.0161

At depth 0.0043

Total 0.0204

The pre-rehabilitation overall oxidation rate of Intermediate heap was 0.0204 kg (O2)

s-1 corresponding to a sulfate generation rate of 0.035 kg (SO4) s-1 or 1100 t (SO4) yr-

1. The estimated post-rehabilitation GORs, due to near surface oxidation, at each of

the probe holes in Intermediate heap are shown in Table 6.9.


Table 6.9 Post-rehabilitation GORs in Intermediate heap

Probe Hole Oxidation layerdepth (m)

IOR(kg(O2) m-3 s-1)

GOR(kg(O2) m-2 s-1)

I01R 2.25 7.11 × 10-8 1.60 × 10-7

I02R 2.09 6.74 × 10-8 1.41 × 10-7

I03R 1.88 9.97 × 10-8 1.87 × 10-7

I04R 1.86 6.88 × 10-8 1.28 × 10-7

I05R 2.03 4.61 × 10-8 9.37 × 10-8

I06R 1.49 5.84 × 10-8 8.71 × 10-8

I07R 2.90 3.67 × 10-8 1.07 × 10-7

I10R 2.44 4.11 × 10-8 1.01 × 10-7

I11R 1.70 8.53 × 10-8 1.45 × 10-7

I12R 1.93 3.77 × 10-8 7.27 × 10-8

I13R 2.66 3.28 × 10-8 8.73 × 10-8

I14R 0.83 1.14 × 10-7 9.46 × 10-8

I15R 2.97 3.24 × 10-8 9.64 × 10-8

I16R 1.74 1.18 × 10-7 2.05 × 10-7

I17R 2.40 5.92 × 10-8 1.42 × 10-7

I18R 2.38 3.88 × 10-8 9.24 × 10-8

I19R 3.08 3.45 × 10-8 1.06 × 10-7

I20R 1.61 8.13 × 10-8 1.31 × 10-7

I21R 1.75 9.52 × 10-8 1.67 × 10-7

NB: The IOR and GOR were estimated using the technique described in Section 6.3

As with the pre-rehabilitation data, the GOR did not vary greatly over the surface of

the heap. If we apply the average GOR of 1.23 x 10-7 kg (O2) m-2 s-1 to the entire

surface of the heap we obtain an overall (near surface) oxidation rate of 0.0085 kg

(O2) s-1 corresponding to a sulfate generation rate of 0.0145 kg (SO4) s-1 or 460 t

(SO4) yr-1.

The negligible oxygen concentrations (and decreasing temperatures) at depth within

the heap indicated that oxidation was no longer occurring at depth. Hence, the

overall oxidation rate of the heap was given by the near surface oxidation rate

determined above.

The Intermediate data were grouped into three-year periods and the overall oxidation

rate is shown as a function of time in Figure 6.6.


Figure 6.6 Overall oxidation rate in Intermediate heap as a function of time

Effect of oxygen diffusion coefficient on calculated oxidation rates

Table 6.10 lists the pre- and post-rehabilitation oxidation rates for Whites heap for a

range of assumed oxygen diffusion coefficients.

Table 6.10 Whites heap oxidation rates for a range of oxygen diffusion coefficients

Oxygen diffusion coefficient (m2 s-1) 1 ×××× 10-6 2 ×××× 10-6 4 ×××× 10-6

Overall oxidation rate – pre (kg s-1) 0.0466 0.0689 0.1137Overall oxidation rate – post (kg s-1) 0.0137 0.0274 0.0548Ratio of pre- to post- oxidation rates 3.40 2.51 2.07

Table 6.11 lists the pre- and post-rehabilitation oxidation rates for Intermediate

heap for a range of oxygen diffusion coefficients

Table 6.11 Intermediate heap oxidation rates for a range of oxygen diffusion coefficients

Oxygen diffusion coefficient (m2 s-1) 1 ×××× 10-6 2 ×××× 10-6 4 ×××× 10-6

Overall oxidation rate – pre (kg s-1) 0.0204 0.0358 0.0666Overall oxidation rate – post (kg s-1) 0.0085 0.0170 0.0340Ratio of pre- to post- oxidation rates 2.40 2.11 1.96

Years

1985-87 1988-90 1991-93 1994-96 1997-

Ove

rall

oxid

atio

n ra

te (k

g (O

2) s

-1)

0.005

0.006

0.007

0.008

0.009

0.010

0.011

0.012


The ratio of pre- to post-rehabilitation oxidation rates is dependent on the diffusion

coefficient, as part of the pre-rehabilitation rates (oxidation at depth) was determined

from heat source profiles. If this component were not present, the ratio would be

independent of the oxygen diffusion coefficient chosen for the waste rock.


The effective oxygen diffusion coefficient of the cover was calculated using the

technique described in Section 6.3. The cover diffusion coefficient has a square root

dependence on the oxygen diffusion coefficient assumed for the waste rock material.

Two values were used for the diffusion coefficient of the waste rock, 1 × 10-6 m2s-1

and 4 × 10-6 m2s-1, in order to obtain a range for the diffusion coefficient of the cover

on Whites and Intermediate heaps. The cover diffusion coefficients were calculated

at each probe hole with average values presented in Tables 6.12 and 6.13.

Table 6.12 Effective diffusion coefficient of the cover on Whites heap

Waste rock diffusion coefficient (m2 s-1)

Data D = 1 ×××× 10-6 m2s-1 D = 4 ×××× 10-6 m2s-1

All (4.0 ± 1.6) × 10-7 (8.0 ± 3.2) × 10-7

Wet season 3.0 × 10-7 6.0 × 10-7

Dry season 4.5 × 10-7 9.0 × 10-7

NB: calculated using the technique described in Section 6.3)

Table 6.13 Effective diffusion coefficient of the cover on Intermediate heap

Waste rock diffusion coefficient (m2 s-1)

Data D = 1 ×××× 10-6 m2s-1 D = 4 ×××× 10-6 m2s-1

All (6.2 ± 0.8) × 10-7 (1.24 ± 0.16) × 10-6

Wet season 5.1 × 10-7 1.01 × 10-6

Dry season 6.2 × 10-7 1.25 × 10-6

NB: calculated using the technique described in Section 6.3)


6.5. DISCUSSION

Infiltration rates

The infiltration rate into Whites dump has increased significantly in the current five-

year monitoring period. Since the 1994/95 wet season it has been higher than the

design specification of 5%.

The latest measurements vary between 5 and 10% indicating that present infiltration

rates are between five and ten times lower than the ~50% infiltration rate estimated

before the cover was put in place.

Wicking from the lysimeters was the principal source of error in the estimation of total

infiltration rates. When estimating the wicking rates during the dry season, the water

level was always at or below the reference level, yet for much of the remainder of the

year the water level in the lysimeter was higher. Intuitively, as the water level rises

towards the top of the lysimeter, wicking losses should increase. However, this effect

was found to result in an error in the calculated infiltration rates of less than 10

mm/year.

The most plausible explanation of the recent data is that the cover on Whites heap is

now a less effective barrier to water flow into the heap and that infiltration rates have

increased significantly during the current monitoring period.

To assess the impact of such an increase in infiltration rate on the pollutant loads

from the heap, it is necessary to estimate the time needed for infiltrating water to flow

to the base of the heap. As water molecules are travelling vertically through the heap

at around 0.5 m/year, the transit time to the base of the heap for these molecules is

of the order of 40 years. Consequently the current oxidation rate has little effect on

short-term pollution loads. These loads are determined by the volume of

groundwater flowing from the base of the heap (identical to the volume of water

infiltrating the surface of the heap) and the concentration of pollutants in this water.

As less than twenty years have elapsed since rehabilitation, the concentration of

pollutants in water at the base of the heap should not have altered significantly.


Hence, the recent observed increase in the infiltration rate should result in a

proportionate increase in flow volumes and hence pollutant loads from Whites heap.


The recent temperature measurements show that the interiors of Whites and

Intermediate heaps have continued to cool. Models of heat conduction indicate that

the rate of cooling in both cases is consistent with the absence of heat sources at

depth within the heaps. Due to the influence of the boundary conditions on the near

surface temperatures, it is more difficult to place an upper limit on the near surface

heat sources. Near surface sources similar to those observed before rehabilitation

are possible.

No greatly elevated temperatures were observed in the interior of Dysons heap. The

measured temperatures (in June 1998) varied between 27 °C and 32 °C, with the

temperature increasing near the batters and with depth. The temperatures do not

appear to be changing with time.

Pore gas oxygen concentration measurements

Generally, the oxygen concentration was high just beneath the cover (5-15 vol%

compared with an atmospheric value of 21 vol%) in all three heaps which indicated

that the covers were only partially successful in limiting the transport of oxygen to the

reaction sites.

Whites heap

A number of observations can be made regarding oxygen concentrations within

Whites heap:

1. Since the mid-1980’s the oxygen concentrations at the base of the cover of

Whites heap have been gradually increasing (see Table 6.2).;

2. Oxygen concentrations in Whites heap were significantly higher during the dry

season (see Table 6.5); and

3. In recent years (~1995 to 1998) the diurnal variations in Whites heap have been

decreasing in magnitude and are now practically negligible.


These three observations could be explained by deterioration in the performance of

the cover with respect to limiting oxygen transport, as indicated by an increase in its

oxygen diffusion coefficient. An increase in the diffusion coefficient of the cover over

both wet and dry seasons would result in a higher flux of oxygen through the cover

and an increase in the oxygen concentration at the base of the cover. A higher

diffusion coefficient in the dry season, intuitively likely as the clay layer partially dries,

would result in higher oxygen concentrations beneath the cover during this season.

The explanation for diurnal variations, put forward previously, centred on

weaknesses being present in the cover at the probe hole locations. Changes in

atmospheric pressure therefore resulted in preferential gas flow along the probe hole

liners and hence large changes in oxygen concentration at the measurement points.

A general increase in the cover permeability (defined as the constant of

proportionality between pressure gradient and gas velocity) would be likely to

accompany an increase in the cover diffusion coefficient. A higher permeability

implies greater gas flow rates for the same drop in pressure. Hence, an increase in

the cover permeability over the entire heap would lead to gas flow would result in

gas flow no longer being confined to the probe hole liners. Such a gas flow should

only penetrate the top metre or so of the heap and hence leave oxygen

concentrations unchanged at depth.

Intermediate heap

As with Whites heap, a number of observations can be made from the oxygen

concentration data from Intermediate:

1. The oxygen concentrations at the base of the cover of Intermediate heap have

been gradually increasing since the mid-1980’s (see Table 6.3);

2. The oxygen concentration at the base of the cover in Intermediate shows a slight

seasonal variation, being higher in the dry (see Table 6.4); and

3. Diurnal variations are observed in the top two metres of Intermediate during the

late wet.

The explanation for these observations is similar to that put forward for Whites. The

oxygen diffusion coefficient of the cover has increased during both the wet and dry

seasons and is slightly higher during the dry. This has led to an increase generally in


the oxygen concentration at the base of the cover with higher concentrations

apparent during the dry season.

Any diurnal variations observed in Intermediate heap over the monitoring period

have been confined to the top two metres of the heap. It appears likely that in this

case weaknesses in the cover were not present near the probe holes and hence gas

flow related to diurnal pressure variations has always occurred over the entire

surface of the heap.

Dysons heap

High oxygen concentrations were measured throughout Dysons heap except for one

oxygen deficient region under probe holes D06R, D07R and D11R. The abundance

of oxygen throughout the heap and the absence of elevated temperatures suggest

that the IOR of the material is generally much lower than the IOR of the material in

Whites and Intermediate.

Oxygen concentrations found beneath the cover were higher than those within the

cover (this was particularly evident during the wet season). The only likely

explanation is that oxygen is transported to the centre of the heap via the uncovered

batters. The presence of lower oxygen concentrations in the cover than in the region

below also suggests that consumption of oxygen was occurring within the cover.

There was virtually no seasonal variation in the oxygen concentration profiles in

Dysons heap. This reinforces the suggestion that gas flow into the heap is primarily

through the batters as oxygen diffusion through the cover would be expected to

increase in the dry season (in line with observations made in Whites and

Intermediate heaps).

No diurnal variations in oxygen concentration were observed in Dysons heap. This

was probably a result of the uncovered batters, which would allow gas flow over their

entire surface (and hence diurnal variations would only occur to a distance of a few

metres in from the sides of the heap).


Oxidation rates

A comparison of the overall oxidation rate in Whites heap before and after

rehabilitation reveals that the oxidation rate (and hence the primary pollutant

generation rate) has been reduced by a factor of between 2.1 and 3.4 by the

rehabilitation measures. A similar comparison using the rates obtained for

Intermediate heap indicate that for this heap the overall oxidation rate has been

reduced by a factor of between 1.9 and 2.4. While these figures represent a large

reduction in pollutant generation rates, it should be noted that significant oxidation

(and hence pollutant generation) is still occurring within Whites and Intermediate

heaps.

By grouping the post-rehabilitation data from Intermediate in three-year periods, the

time dependence of the overall oxidation rate was determined. The overall oxidation

rate was (7.0 ± 1.1) × 10-3 kg (O2) s-1 during the 1985-87 period and has increased

as a function of time to (10.2 ± 0.9) × 10-3 kg (O2) s-1 (1997 onwards). This indicates

that the cover performance has deteriorated with time.

A similar analysis of Whites heap shows no conclusive increase in the overall

oxidation rate as a function of time, being (1.29 ± 0.25) × 10-2 kg (O2) s-1 in 1988-90

and (1.44 ± 0.21) × 10-2 kg (O2) s-1 in 1997/98.

It is interesting to compare the estimated rates of sulfate production within the heaps

with the sulfate loads observed in drainage. As Whites heap was found to be

responsible for between 25 and 35% of the total load of copper, manganese and zinc

from the site (Davy 1975, Table 6.17), it seems reasonable to assume that it was the

source of a similar proportion of the sulfate. The average annual sulfate load from

the site between 1969 and 1974 was 8000 t (Kraatz 1998, Table 3.1). This suggests

that, in the steady state, around 2000 to 2800 t of sulfate were generated in Whites

heap each year prior to rehabilitation, in good agreement with the 2520 t calculated

from the temperature and oxygen concentration profiles (section 6.4).

Intermediate heap was responsible for approximately 20 to 25% of the pre-

rehabilitation loads of copper and zinc (Davy 1975, Table 6.17). Assuming a similar

proportion of the sulfate emanated from Intermediate heap and that the system was


in steady state with respect to water flow, around 1600 to 2000 t of sulfate were

generated within the heap each year. This is in reasonable agreement with the 1100

t calculated from the temperature and oxygen concentration profiles (section 6.4).

The IOR of the oxidising material in Intermediate is on average five times greater

than the IOR of oxidising material in Whites. This is almost certainly a result of the

reshaping of Intermediate heap prior to cover emplacement. During reshaping a

large volume from a highly oxidising region was spread across the surface of the

dump. As the surface few metres is the region in which oxidation is currently

occurring, a relatively high measured IOR would be expected in Intermediate heap.

The interior of Dysons heap is well oxygenated suggesting that the rate of oxygen

supply, and hence the oxidation rate, has not been significantly reduced by the

placement of the cover on the top surface. The observed reduction in pollutant load

from the dump was therefore almost certainly due to a reduction in the infiltration

rate.

The long-term implications on pollutant loads from the overburden heaps at Rum

Jungle will depend on whether secondary mineralisation occurs within the heaps.

Because the reduction in the rate of water flow through the heaps is greater than the

rate at which pollutants are produced, pollutant concentrations in pore water would

be expected to rise. If as a consequence the pore water becomes saturated with a

pollutant, precipitation of some of this pollutant will occur (secondary mineralisation).

Hence, for a given water infiltration rate, secondary mineralisation can limit the

pollutant load from a dump.

If secondary mineralisation is occurring in the Rum Jungle overburden heaps, any

future changes in pollutant loads from the heaps should be proportional to changes

in the water infiltration rate. However, if secondary mineralisation is not occurring

and the pollutant concentration in pore water is not limited, the pollutant loads would

be expected to increase over the next 20 to 30 years to between one half and one

third of their value prior to rehabilitation.



The estimates of the oxygen diffusion coefficient within the cover are high when

compared with measurements on compacted clay covers by ANSTO at other

locations. The largest estimate of the diffusion coefficient of the cover on

Intermediate heap (1.25 ×10-6 m2 s-1) is a value more typical of waste rock.

There is a significant seasonal variation in the estimated diffusion coefficient in both

heaps. The greater value observed in the dry is consistent with the picture of a cover

which partially dries during the dry season allowing greater oxygen penetration.

6.6. CONCLUSIONS

This chapter has aimed to quantify the effectiveness of the covers placed on the

three overburden heaps at Rum Jungle. The effectiveness of these covers was

estimated by comparing the pre- and post-rehabilitation water infiltration and overall

oxidation rates.

The following conclusions can be drawn:

• The infiltration rate into Whites heap has increased significantly during the

current five-year monitoring period and has been above the design

specification of 5% for the last four years. However, it is still between five and

ten times lower than the estimated rate before rehabilitation;

• The overall oxidation rate in Whites heap is approximately a factor of three

lower than the pre-rehabilitation overall oxidation rate, and corresponds to the

production of 740 t of sulfate annually. It is remaining steady or increasing

slightly with time;

• The overall oxidation rate in Intermediate heap is approximately a factor of

two lower than the pre-rehabilitation overall oxidation rate, and corresponds to

the production of 460 t of sulfate annually. There are indications that it is

increasing with time;

• The overall oxidation rate of Dysons heap has not been significantly reduced

by rehabilitation. The waste rock is oxidising at a generally low rate and

sufficient oxygen is being transported through the batters to maintain this rate

of oxidation. It can be concluded that the cover placed on Dysons heap is


ineffective in reducing the oxidation rate for low oxidation rate material.

However, given the similarity between the cover on the top surface of Dysons

and the covers on Whites and Intermediate, the infiltration rate is expected to

have been greatly reduced;

• Neither the temperatures nor oxygen concentrations within Dysons heap

appear to be changing with time;

• The oxygen diffusion coefficients of the covers on Whites and Intermediate

heaps are relatively high and seasonally dependent with higher oxygen

diffusion coefficients found in the dry season. This is consistent with a picture

of a cover, which allows significant oxygen penetration year round and

partially dries during the dry season allowing greater oxygen penetration; and

• Future pollutant loads from the overburden heaps will depend on the presence

or absence of secondary mineralisation. If secondary mineralisation is

occurring, any future changes in pollutant loads from the heaps will be

proportional to changes in the water infiltration rate. However, if secondary

mineralisation is not occurring and the pollutant concentration in pore water is

not limited, the pollutant loads from the heaps would be expected to increase

over the next 20 to 30 years to between one half and one third of their value

prior to rehabilitation.

6.7. SUGGESTIONS FOR FURTHER WORK

While it is recognised that the monitoring to date demonstrates the original objectives

have been achieved, it is nevertheless worth exploring other scientific questions in

order to fully understand the site and processes that operate and influence the sites

bio-physical behaviour. As such the following additional suggestions are made for

further consideration:

• It is suggested that a program of work be undertaken to determine the

reasons for the deterioration in cover performance. The results may have

important implications for the long-term use of covers placed on mine waste.

This program of work should include a field investigation of the current

physical, hydraulic and gas diffusion properties of the cover;


• It is suggested that a reduced monitoring program be undertaken over the

next five years to identify any further changes in the infiltration and overall

oxidation rates of Whites and Intermediate heaps;

• It is suggested that the monitoring program on Dysons heap is discontinued

as neither oxygen concentrations nor temperatures appear to be changing

with time; and

• It is further suggested that a program of work be undertaken to determine if

the deterioration in the performance of the covers will lead to a significantly

increased ecological risk to the Finniss River.

This program will need to answer the following questions:

• Has the water infiltration rate into Intermediate heap also increased with time?

• What is the mechanism of water transport through the waste rock dumps?

• Are pollutant concentrations in heap pore water proportional to the oxidation

rate or limited by geochemical processes?

• What are the current pollutant loads from Whites and Intermediate heaps?

• What will be the future pollutant loads from the heaps?

• What is the site hydrology?

• What interaction is there between the ground water and the material in the site

aquifers?

• What are the time scales between release of pollutants from the heaps and

appearance in the river?

• Will any conceivable pollutant loads in future lead to significantly increased

ecological risk to the Finniss River?


7. MEASURES OF ECOLOGICAL IMPACT IN THE FINNISS RIVERDOWNSTREAM OF THE RUM JUNGLE REHABILITATED SITE1993-98

J TWINING AND S MARKICHEnvironment Division, ANSTO

C EDWARDSDepartment of Infrastructure, Planning and Environment, Darwin NT.

7.1. INTRODUCTION

The principal objective for inclusion of biological studies in the Finniss River system

within the overall monitoring effort at Rum Jungle was to determine the ecological

success of the remedial activities that were carried out in the early-mid 1980s

(Kraatz and Applegate 1992). The degree of success would be measured against

two benchmarks. The first benchmark was the significant level of deleterious

biological impact that was observed in the East Branch and main Finniss River prior

to remediation (Allen and Verhoeven 1986). The second benchmark was the relative

health of sites, which had not been affected by drainage from Rum Jungle, and

hence could be considered reference sites.

In line with current philosophy, it was important that the ecological condition of the

river be measured at several trophic levels (that is plants, herbivores, predators and

recyclers) to assess the overall structural and functional integrity of the system. This

approach is also amenable to the application of Ecological Risk Assessment (ERA).

In ERA a range of sensitivities in the exposed populations of plants and animals is

used to determine the probable proportional impact of any hazard (in this case

effluent from Rum Jungle) on the biota likely to be present. The pertinence of this

approach from a regulatory perspective is that ERA will be increasingly used in

future to evaluate management options for any site. The principles of ERA have

been used in developing the current revisions to the national water quality guidelines

and will be required practice in future (ANZECC and ARMCANZ 2001). Ecological

measures are recognised as the most relevant indices to use, over and above the

more straightforward, but simplistic, measures of contaminant concentrations.


At the outset of the 1993-1998 monitoring program, biologists in ANSTO’s

Environment Division agreed to undertake two activities within the five-year period.

These were:

• A study of benthic and epi-benthic macro-invertebrates; and

• An assessment of archival monitoring of bioavailable pollution using

freshwater mussels.

At the 1997 meeting, the Rum Jungle Monitoring Committee also determined that

ANSTO would undertake a preliminary study of the current ecological impact of the

first annual flush of polluted water down the East Branch into the Finniss River.

The macro-invertebrate sampling comprised studies within both the East Branch

(that drains the Rum Jungle site) and the main Finniss River. Archival monitoring

was restricted to sites where mussels could be found. The first flush study

concentrated on, but was not restricted to, sites in the East Branch downstream of

the rehabilitation site and Finniss River sites adjacent to, or just downstream of, the

confluence.

This report will refer to each sub-project separately then draw together general

findings and suggestions for further research. Detailed data sets for each of the

studies are available from the lead author.

7.2. MACROINVERTEBRATE SURVEYS - FINNISS RIVER

Introduction

Within the main river, the study comprised a series of surveys of decapod

crustaceans. The rationale for this work was that:

• These animals were shown to be severely influenced by the Rum Jungle

effluent by their absence from the impacted zone of the river that was

identified during the 1973/1974 surveys;

• Any organism relying on calcium carbonate to harden its exoskeleton will be

susceptible to pH stress; and


• Ecotoxicological studies have shown some species within this taxonomic

group to be amongst the most sensitive animals to copper pollution (Williams

et al.1991).

The aims of the study were to:

• Assess the impact of contemporary effluent from Rum Jungle on these taxa

within the river downstream of Rum Jungle in reference to uncontaminated

sites; and

• Determine the degree of improvement, if any, when compared with the

observations made in 1973/1974 prior to remediation work at Rum Jungle.

Methods

Because of size and behavioural differences, the animals were sampled using two

main techniques that were standardised for effort to validate comparisons between

each survey. These were the use of dip nets to sweep within immersed vegetation

and the use of baited traps of two sizes set for a period of approximately four hours

from dusk along the edge of the sites. We are grateful to the NT Department of

Infrastructure, Planning and Environment (DIPE) for providing technical support for

most of this work.

Water quality measurements and water samples were collected to provide

information on the physicochemical parameters at each site. Three surveys were

carried out at successively later times in the dry season over succeeding years.

Animals were collected and preserved in the field. At ANSTO’s Lucas Heights

Research Laboratory (LHRL) the samples were sorted, counted and measured.

Chemical analyses of water samples were also performed. All appropriate collection,

export and import permits were acquired from the relevant State and Territory

regulatory authorities.

Taxonomic identification was required for the species collected during the first survey

in 1994 and these Type specimens were used as reference for all samples. We are

grateful to Dr Karen Coombes of the NT Museum of Applied Arts and Sciences who

confirmed or corrected our identifications.



In general, the patterns of distribution and abundance observed are highly variable,

which was expected given the dynamic nature of the habitat conditions between

years and across seasons, and between locations. A summary of catch by genera,

normalised for effort, at sites in the Finniss River for each year is given in Table 7.1.

Site numbers are consistent with those given in previous reports (eg Jeffree and

Twining, 1998).

Table 7.1 Annual normalised catches summary for decapod genera.

Site 1 2 3 4 5 6

Year Family 30 km 14 2.5 1.4 - 0.5 - 18 km

A 99 0 0 0 168 123

1994 M 102 27 51 82 49 168

C 2 4 26 20 16 48

A 390 8 48 20 486 65

1995 M 28 49 18 40 17 6

C 3 2 0 0 1 13

A 24 352 2092 560 600 780

1996 M 53 161 376 31 18 15

C 0 0 6 25 0 0

Distance is in Finniss River kilometres downstream of the East Branch confluence.

(A = Family Atyidae ‘shrimps’ - Caridina spp. and Caridinides wilkinsi; M = Family Palaemonidaeprawns’ - Macrobrachium bullatum; C = Family Parastracidae ‘yabbies’ - Cherax quadricarinatus)

The results are interesting in that they initially showed a marked reduction in the

populations of Atyids (that reduce to zero abundance in 1994, Table 7.1, Figure 7.1)

and Palaemonids, for at least 14 km downstream of the confluence of the main river

and its East Branch when compared with unimpacted sites (Sites 1,5 and 6, Figure

7.2a). This mirrored the earlier response seen in the fish populations by Jeffree and

Williams (1975) that has subsequently improved post remediation. Decapods were

thus showing a more sensitive response to rehabilitation site generated pollution

than were the fish. However, some improvement in Atyid populations was noted in

the latter surveys. In distinct contrast to patterns observed in previous years,

enhanced numbers of crustacea were collected within the polluted zone of the river

in 1996 (Figure 7.1). Small sized individuals dominated the large populations in that


year, ie due to breeding during the dry season. These results indicated that the

residual impact of rehabilitated site wastes flowing into the main river from the East

Branch, in the period subsequent to the remediation at Rum Jungle, was limited. The

data further suggest that the sensitive decapod populations were able to recover,

more by breeding than by immigration, in the low flow periods of the year. An

alternative or additional interpretation may be that the improvement in sequential

years was reflecting a general improvement in the Finniss River system through

time.

Low populations of decapods were found in the Finniss, downstream of the East

Branch at times closer to the period of inflow from Rum Jungle, at the start of the wet

season, as observed in previous years (Figure 7.1). This indicated an annual impact

on populations of crustaceans was still occurring in the main river. Refer to the later

section of this report, on the impacts of the first flush, for supporting evidence.

Nonetheless, prior to remediation, no live crustacea were collected at any time of the

year from the polluted zone of the main river. Atyids are now common at FR1 in

contrast to 1973/1974 when none were found at any regular sampling site

downstream of the East Branch. These results imply a marked improvement in

Finniss River water quality.

Some confounding effects may have influenced the observations made. For

example, it is uncertain what effect an unexpected early flow in the Finniss had on

the sampling results in 1996. The highest numbers of individuals, predominantly

small, were collected at the site with the strongest flow at the time of sampling.

Nonetheless, other sites with more typical dry season flow rates, both before and

after the spate, generally also had higher numbers than in previous years.


Distance from East Branch confluence (km)

-30 -20 -10 0 10 20 30 40

Num

bers

of I

ndiv

idua

ls

0

500

1000

1500

2000

2500

October 1996

August 1995

May 1994

Figure 7.1 Populations of Atyids at sites in the Finniss River over three sampling periods.Normalised for effort

Inconsistencies are apparent between the surveys carried out. For example, the

decline in Cherax sp. progressively downstream noted in 1994 was not repeated in

subsequent years (Table 7.1). Cherax sp. were in lower abundance and only two

were captured and released in the impacted zone of the river in 1995. In contrast,

the only captures in 1996 were within the impacted zone. In 1994, the Palaemonid

shrimp, Macrobrachium bullatum, was found at all sites. However, the numbers were

much reduced in 1995. Whilst we are trying to draw inferences from a restricted

database in relation to natural variability within the system, one possible explanation

for the reduced abundance of these larger species was predation by the remarkable

numbers of small barramundi, Lates calcarifer, that were observed at all sites. These

fish include significant quantities of Crustacea in their diet.


7.3. DECAPOD SURVEYS - EAST BRANCH

Introduction

In 1994 a one-off survey of decapods was undertaken in the East Branch. The

rationale, aims and methodology were as for the main river survey. This section also

contains observations made opportunistically during 1996.


The survey showed low populations of decapod genera in the East Branch (Table

7.2). This was not unexpected in an ephemeral stream, as decapod crustaceans

cannot tolerate any lack of water.

Table 7.2 Normalised decapod catch summary for the East Branch, 1994. Distances arekilometres downstream of Rum Jungle gauging station GS8150200.

Main channel pools Side-streampools

Site No. 1 2 3 4 5 6 8 2s 4skm 8.1 6.4 6.5 5.7 3.0 0.1 -0.3 (6.5) (6.0)Shrimps 0 0 0 0 0 0 0 0 0Prawns 12 4 1 0 0 0 0 5 0Crabs 0 1 1 0 0 0 71 3 5Yabbies 0 0 0 0 0 0 0 0 0

There was also a rapid decline to zero population upstream of the confluence with

the main river. Populations of decapods only re-appeared upstream of this point in

sidestreams or above Rum Jungle. This result implied that Rum Jungle was still

affecting decapod populations downstream in the East Branch. Nonetheless, the

recent distributions of Crustacea were a marked improvement over those observed

in 1974/75. At that time, no live decapods were found in the East Branch

downstream of Rum Jungle despite a more intensive sampling regime than that

undertaken in 1994.

The presence of crabs instead of yabbies in un-impacted areas of the East Branch,

and vice versa in the main stream, suggests that these two genera are competitive


for similar habitat and that the crabs are more tolerant of loss of standing water

whilst the Cherax sp. are more successful in free water bodies.

Several dead Macrobrachium were also observed in the main channel of the East

Branch, below GS 8150097, in the period of days following the first flush, which

came earlier than expected in 1996. This observation implied two things. Firstly, that

there were populations of this taxon able to recolonise the stream at the onset of flow

each year and secondly, that the first flush was still a mechanism for detriment in the

system, the assumption being that the mortality was attributable to Rum Jungle

effluent rather than to natural causes. The simultaneous mortality of the catfish,

Neosilurus arius, a fish known to be tolerant of most of the natural factors likely to

induce fish kills such as oxygen depletion or elevated suspended solids, supported

this assumption. Further information on this effect is given in the section on the first

flush observations later in this report.

7.4. BENTHIC MACROINVERTEBRATE SURVEYS – TEMPORAL AND SPATIALDISTRIBUTION IN THE EAST BRANCH

Introduction

In view of the results of the earlier post-rehabilitation survey (Ferris and Jackson,

1998), a further study was initiated in 1994 to investigate the temporal effect of

effluent from Rum Jungle on the benthic macroinvertebrate community in the East

Branch. The specific aims of the project were as follows:

• To quantitatively assess the temporal impact of variable heavy metal

concentrations in surface waters on the benthic macroinvertebrate community

composition;

• To determine if any recovery was evident with increased distance downstream

of Rum Jungle rehabilitated site as well as throughout the year; and

• To examine the relationship between water quality and macroinvertebrate

community composition over the recessional flow period in the East Branch.


Site selection

As displayed in Figures 7.2a and 7.2b, twelve sites were selected in the East Branch

catchment (three pairs of reference sites as well as three pairs of impacted sites).

Additionally, a site upstream (FR5) and downstream (FR4) of the confluence with the

Finniss River proper and two sites in a comparable catchment (Little Finniss River)

were also sampled. These Little Finniss River sites (LFR9 and LFR8) are at

approximately the same distance from the source and also separated by a similar

distance as reference and impacted sites within the East Branch catchment.

The three pairs of sites below Rum Jungle were selected to coincide with the 1993

survey. Site EB5I is located immediately below the Tailings Creek confluence, site

EB4 is located at GS8150097 and EB2 is downstream of the Hanna’s Spring

confluence. All sites comprised paired replicate sample areas, upstream and

downstream.

Following is a brief rationale for site selection for this study:

• Balanced paired sites in the East Branch were selected for univariate ANOVA;

• Little Finniss River (LFR) sites were selected for comparison to the East Branch

using Bray-Curtis similarity measures; and

• Finniss River sites upstream and downstream of the East Branch confluence

were selected for similarity comparisons (Bray-Curtis) as well as for temporal

comparisons.


a) Location of study area and main sampling sites on the Finniss River, NT

b) Detail showing macroinvertebrate sampling sites on the East Branch and adjacent to itsconfluence with the Finniss River

Figure 7.2 Location of study area and main sampling sites

Sampling frequency

The 1994 survey commenced in August with the intention to sample every six to

eight weeks, however, due to drying up of the East Branch and flooding during the

1994/1995 wet season, only eight full sampling runs were completed. Table 7.3

displays the study period with complete sampling runs indicated.


Table 7.3 Sampling frequency during the 1994/1995 macroinvertebrate survey.

1994 1995 1995

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

I I I I I I I I I I I I I I

^ ^ ^ ^ ^ ^ ^ ^

Run: 1 4 5 6 7 8 9 10

As displayed in Table 7.3, sampling was reduced during the late dry of 1994 due to

extensive drying up of the majority of sampling sites. Wet season sampling involved

pre-flow sampling run (Run 4) and high flow sampling (Run 5). Sampling was

intensified during the recessional flow period to monthly intervals (Runs 6 - 10) to

evaluate the effect this critical period has on macroinvertebrate community

composition.

Methodology and materials

Physical and chemical

At all sites on all sampling runs, four replicate sets of water physicochemical

measurements (water temperature, electrical conductivity, turbidity, dissolved

oxygen and pH) were recorded using a Horiba U-10 multiparameter water quality

meter.

Additionally, 500 mL unfiltered water samples were collected below the surface. The

samples were analysed at the NT Water Resources Laboratory using: flame atomic

absorption (FAA) for the major cations Ca2+ and Mg2+; alkalinity titrations for

hardness (as CaCO3), OH-, CO32- and HCO3-; and the barium sulphate precipitation

method for SO42- (APHA method 4500). For trace metal analysis (iron, copper,

manganese, zinc, cobalt, nickel) the samples were either analysed for total metal

level or filtrate and residue. In the latter case samples were filtered through a 0.45

µm filter then the filtrate was acidified (<pH 2) and the residue digested using nitric

acid. Metals in high concentration were analysed using FAA (APHA method 3111B),

lower concentration metals by graphite furnace (APHA method 3113). In the former

case samples analysed for total metal level were acidified and digested using nitric


acid then analysed using either FAA or graphite furnace (APHA 3111B and 3113

respectively).

Macroinvertebrate

At each site on all sampling runs, six randomly selected replicate macroinvertebrate

samples were collected from a sand habitat using a quantitative benthic suction

sampling device. This device consists of an enclosed collector with a 0.05 m2

capture area with access through a glove box arm attachment allowing substrate

agitation. The suspended macroinvertebrates and organic detritus are then sucked

away by an electric bilge pump arrangement and into a 300 µm tapered nylon mesh

net and 700 mL wide mouth, removable container. Water passing through the net

was then recycled back into the collector. Each replicate sample was collected over

a minute of pump operation before being preserved in 70% ethanol for laboratory

sorting and identification.

The macroinvertebrates were then removed from the detritus in the laboratory in two

fractions, greater than 2.34 mm coarse fraction and a 2.34 mm – 300 µm fine

fraction. The coarse fraction was sorted completely with all macroinvertebrates

removed and the fine fraction was sub-sampled and a 10% fraction sorted

completely. All macroinvertebrates were counted and identified to the taxonomic

level of Family, except Oligochaetes (worms) which were left at Class level and

Chironomidae, which were identified to sub-Family level. All macroinvertebrate data

were expressed as abundance of represented taxa for each replicate sample at each

site and sampling run.


Water quality

From the range of chemical parameters analysed in collected water samples, the

general trend in pollution load is evidenced by the three examples below. Electrical

conductivity (EC) corresponded closely with heavy metal load and was thus a useful

indicator of total pollution load.


As shown in Figure 7.3, four selected sites in the East Branch catchment showed

different temporal trends in pollution load. The recessional flow period from April

1995 to July 1995 showed a steady increase in EC in all sites displayed except EB2

(B). The latter is located immediately below Hanna’s Spring confluence and as such

may experience spring-fed water diluting the East Branch water and maintaining a

constant EC. Additionally, sequential sites downstream from Rum Jungle indicated

highest pollution load levels at the site closest to Rum Jungle (EB5IB) and a gradual

decrease in pollution load through EB4 (A) and down to EB2 (B).

Both copper and zinc levels, displayed in Figure 7.4 and Figure 7.5, mirrored the EC

throughout the recessional flow period. Again, the highest levels occurred

immediately downstream of Rum Jungle and decreased with increasing distance

downstream. During the recessional flow period, EB5I (B) experienced significant

increases in heavy metal concentrations (both copper and zinc). However, the other

downstream sites actually experienced a gradual reduction in metal level over time,

until cessation of flow at EB4 (defined as the moment at which water ceases to pass

through the V-notch weir at GS 8150097).

0.0000.5001.0001.5002.0002.5003.0003.5004.0004.500

Jul-9

4

Aug-

94

Sep-

94

Oct

-94

Nov

-94

Dec

-94

Jan-

95

Feb-

95

Mar

-95

Apr-9

5

May

-95

Jun-

95

Jul-9

5

Aug-

95

Sep-

95

Oct

-95

Date

E.C

. (m

Scm

-1) EB5I(B)

EB4(A)EB2(B)EB8(C)End of Flow

Figure 7.3 Electrical Conductivity (EC) at four sites in the East Branch


0500

100015002000250030003500400045005000

Jul-9

4

Aug-

94

Sep-

94

Oct

-94

Nov

-94

Dec

-94

Jan-

95

Feb-

95

Mar

-95

Apr-9

5

May

-95

Jun-

95

Jul-9

5

Aug-

95

Sep-

95

Oct

-95

Date

Cu

( µµ µµgL

-1)

EB5I(B)EB4(A)EB2(B)EB8(C)End of Flow

Figure 7.4 Copper concentrations at four sites in the East Branch

0

2000

4000

6000

8000

10000

12000

Jul-9

4

Aug-

94

Sep-

94

Oct

-94

Nov

-94

Dec

-94

Jan-

95

Feb-

95

Mar

-95

Apr-9

5

May

-95

Jun-

95

Jul-9

5

Aug-

95

Sep-

95

Oct

-95

Date

Zn ( µµ µµ

gL-1

)

EB5I(B)EB4(A)EB2(B)EB8(C)End of Flow

Figure 7.5 Zinc concentrations at four sites in the East Branch

This result suggested that the persistent low flow at EB4 may have represented

spring-fed seepage or delayed run-off from the catchment downstream of Rum

Jungle rather than any substantial component of effluent from Rum Jungle itself or

further upstream. The latter appeared to be generally retained and concentrated in

the creek bed closer to Rum Jungle. The drop in metal concentrations at EB5I was

probably due to co-precipitation within the floc that regularly occurs at that site and

upstream as the system dries out. Dilution was unlikely as the EC continued to rise

at the same time. The pH values also decreased steadily.

In terms of EC and specific copper and zinc levels, all impacted sites downstream of

Rum Jungle were consistently higher than the reference site EB8(C). Site EB2 (B),

furthest downstream from Rum Jungle showed some recovery toward background


reference levels during recessional flow. This was further aided by continued dilution

from Hanna’s Spring.

Macroinvertebrates

The following results were based on averaged data from the sampling runs of the

mid wet-season (1995), through the recessional flow period to August 1995. With

reference to Table 7.3, Runs 5,6,8 and 10 had all replicates averaged to a single

abundance value at each site. Furthermore, in Figures 7.6 and 7.7, paired sites were

averaged to a location abundance value and all reference sites (excluding FR4 and

FR5) were averaged to an AVG.REF value. FR4 and FR5 were excluded on the

basis that these two sites are located in the main Finniss River, which is a much

larger, more permanent and more diverse system and, on examination of the

collated data, contains a much greater array of macroinvertebrate families. All other

reference sites data were from intermittent, smaller catchments and therefore more

comparable to those sites downstream of Rum Jungle. An initial comparison of the

total number of taxa present at sites in the study area is provided in Figure 7.6.

0.02.04.06.08.0

10.012.014.0

Feb-

95

Apr-9

5

Jun-

95

Aug-

95

Date

No.

of t

axa

(fam

ilies

)

EB2EB4EB5IAVG.REF

Figure 7.6 Total number of taxa (families) at selected sites in the East Branch catchmentduring the recessional flow period

The averaged number of taxa in the reference sites (AVG.REF) was consistently

higher than at sites downstream of Rum Jungle on all sampling runs. As indicated,

reference sites had on average 12-14 different taxa present from February 1995 to

June 1995. After cessation of flow this reduced to slightly less than 10 taxa, possibly

due to isolation of sites leading to a more similar aquatic environment and hence


more similar community structure. Impacted sites indicated a more divergent

macroinvertebrate community during peak wet season flow and a stabilisation and

convergence when flow levels fell and eventually ceased (July 1995). The number of

taxa in impacted sites was (except for Run 5) consistently less than half that of the

AVG.REF sites. No real improvement in taxon number was evident with distance

downstream or during the period of observation. The wet season sample showed a

slight increase in taxa number which may be due in part to downstream drift, and the

overriding influence of flood flow levels.

Contrary to the relatively stable results depicting total number of taxa, Figure 7.7

indicates much more variation in total abundances (total number of animals)

between sample times.

1.0

10.0

100.0

1000.0

Feb-

95

Apr-9

5

Jun-

95

Aug-

95

Date

No.

of a

nim

als

EB2EB4EB5IAVG.REF

Figure 7.7 Average abundance (number of animals) at sites in the East Branch catchmentduring the recessional flow period

As shown above, the AVG.REF sites always had much higher abundances than

impacted sites. All sites (reference and impacted) were noticeably depauperate

during the wet season (February 1995) due to catastrophic drift and reduction in

protected habitats. During recessional flow (April 1995 to August 1995) all sites

showed a large increase in the number of animals over time. Further, impacted sites

diverged corresponding to increasing distance from Rum Jungle. As shown in Figure

7.7, especially in the June 1995 and August 1995 sampling runs, the sites closer to

Rum Jungle have fewer numbers of animals present.


When comparing Figure 7.6 and Figure 7.7 to the water quality results shown in

Figure’s 7.4 to 7.6 there appeared to be a strong relationship between total

abundance at distances from Rum Jungle and decreasing pollution loads. This was

especially apparent during the recessional flow period. There was less of a temporal

trend in the total number of taxa, however a strong spatial difference in taxa number

was observed when reference sites were compared to impacted sites. The

separation of impacted site abundances in June 1995 and August 1995 (in Figure

7.7) suggested some spatial recovery of sites furthest from Rum Jungle (EB2) as

heavy metal loads in the East Branch as a whole increased substantially over the

same period.

A comparison of Bray-Curtis similarities of all four mid-wet season runs (Run 5,6,8

and 10) using multivariate cluster and ordination programs produced the dendrogram

shown in Figure 7.8 and the ordination plot in Figure 7.9.

Figure 7.8 Dendrogram representing Bray-Curtis similarities of all averaged sites from runs5, 6, 8 and 10.

NB: A, B and C represent the clusters pictured in Figure 7.9.

10LF

R910

FR5

8LFR

86L

FR9

10FC 8F

C6F

C6L

FR8

6EB8

6EB4

S8L

FR9

8EB8

8EB4

S8F

R58F

R410

LFR8

10FR

410

EB8

5LFR

95L

FR8

5EB8 5FC

5EB4

S5E

B5I

5EB2

5EB4

10EB

5I6E

B210

EB4

10EB

26E

B5I

8EB2

8EB5

I8E

B46E

B4

Reference sites from runs 6, 8and 10

Reference andimpacted sitesfrom run 5

Impacted sitesfrom runs 6, 8and 10

A B C


For ease of comparison, groups A, B, and C were assigned to data in both figures.

These figures complement the conclusions from Figures 7.6 and 7.7 by indicating all

reference sites from Runs 6, 8 and 10 as a single group (A). All impacted sites from

Runs 6, 8 and 10 were grouped together (C) and all sites from Run 5, collected at

the peak of flow (Feb.1995), grouped in a loosely contained group (B) as indicated in

Figure 7.9. The ordination plot gives a two dimensional representation of the

similarity of each site to all other sites over all four runs. The greater the distance

between sites, the more dissimilar they were. Group B in Figure 7.9 showed the

general lack of similarity between both reference sites and impacted sites during wet

season flow, especially when compared to the reference sites in group A which were

strongly associated throughout the recessional flow period. Nonetheless, samples 1,

2 and 3 from impacted East Branch sites tended to cluster towards the impacted

sites from other runs (Group C).

Group C also showed a strong similarity between impacted sites. Note that samples

from site EB2 (9,17,27) occurred on the reference side of group C, again supporting

the conclusion that some recovery was evident in this site.

Figure 7.9 Multi Dimensional Scaling ordination of Bray-Curtis similarities from all averagedsites from runs 5, 6, 8 and 10

KEY: RUN SITE RUN SITE 1 5 EB2 19 8 EB5I 2 5 EB4 20 8 EB4S 3 5 EB5I 21 8 EB8 4 5 EB4S 22 8 FC 5 5 EB8 23 8 LFR8 6 5 FC 24 8 LFR9 7 5 LFR8 25 8 FR4 8 5 LFR9 26 8 FR5 9 6 EB2 27 10 EB2 10 6 EB4 28 10 EB4 11 6 EB5I 29 10 EB5I 12 6 EB4S 30 10 EB8 13 6 EB8 31 10 FC 14 6 FC 32 10 FR4 15 6 LFR8 33 10 FR5 16 6 LFR9 34 10 LFR8 17 8 EB2 35 10 LFR9 18 8 EB4

5

7

64

81

3

2

28

1929

1110182717

9 C

2133

35 1424

26

22

121323

2016

31 15

34

323025

A

B


When comparing the main Finniss River sites (FR4 and FR5) over the two sampling

runs (8 and 10), some impact was still obvious downstream of the East Branch

confluence. Run 8 showed there to be only 12 taxa and as few as 280 individuals on

average in FR4 samples, which was low in comparison with FR5 taxa and average

abundance (22 and 908 respectively). This observation was most probably due to

the localised effect of continued recessional flow from the East Branch having the

short term effect of increasing contaminant levels in the main Finniss River (which

was also experiencing recessional flow). When compared to the average number of

taxa and abundances from all other reference sites (13 taxa and 667

macroinvertebrates per sample), the number of taxa was not significantly reduced at

site FR4; however, there was a greater than 50 % reduction in the abundance of

invertebrates. FR5 was significantly richer in taxa as well as abundance.

A comparison of Run 10 to Run 8 data indicated that the cessation of flow from the

East Branch, coupled with the previously mentioned natural reduction in taxa number

(as the dry season progresses), can be recognised by a decrease in taxa number in

all sites. There was also as a reduced difference between sites. Site FR4, FR5 and

the AVG.REF sites respectively had 6, 13 and 10 taxa present. The abundance of

macroinvertebrates at each site also dropped in both FR5 (down to 767) and the

AVG.REF (down to 480), but not in FR4 which shows an increase in abundance (up

to 397). This increase at FR4 may indicate a recovery in the macroinvertebrate

community resulting from cessation of East Branch input and a ‘flushing’ effect of

continued flow in the Finniss River. The differences between sites in average

abundance was also reduced from Run 8 to Run 10 with FR4 even more closely

resembling the other reference sites.

Conclusion

In conclusion, a strong relationship was apparent between water chemistry

downstream of Rum Jungle rehabilitated site and macroinvertebrate community

composition. Because of the quantitative nature of this project and the small,

sampling unit size (0.05 m2) in each replicate, the overall taxa list was not as

extensive as previous studies, which sampled a larger area. Conclusions from the

1993 macroinvertebrate survey (Ferris and Jackson, 1998), that indicated some

recovery in the number of macroinvertebrate taxa with increasing distance


downstream from Rum Jungle, are not (for the reasons given above) substantiated

by the findings of this study. However, examining the macroinvertebrate

abundances has given support to the previous spatial survey and has shown an

increase in abundance with increasing distance from Rum Jungle. All impacted sites

downstream of Rum Jungle rehabilitated site were still depauperate in both the

number of macroinvertebrate taxa present as well as the total number of animals

present per unit area when compared with reference sites.

Additionally, macroinvertebrate data from the main Finniss River sites indicate

continued impact from the East Branch, especially during late recessional flow

periods. Once flow from the East Branch ceased some recovery in

macroinvertebrate abundance was evident in the Finniss River as continued flow

diluted any residual East Branch contamination.

Because of the different sampling method employed in this study, only tentative

comparisons can be made with both the 1993 survey and also the 1973/1974

survey. All three studies showed significant reductions in the macroinvertebrate taxa

at impacted sites downstream of Rum Jungle rehabilitated site. The 1993 study

showed significant increases in macroinvertebrate taxa compared to the 1973/74

survey. This study failed to show any significant recovery in the number of taxa,

which was not unexpected given the difference in sampling strategy. However, the

recent survey did indicate slight recovery, that is increased abundances, in relation

to increased distance from Rum Jungle.

7.5. ARCHIVAL MONITORING STUDY

Introduction

Previous collaborative studies involving ANSTO biologists had identified the

possibility of using surface analysis techniques, such as Secondary Ion Mass

Spectrometry (SIMS), to determine the metal levels within annual laminations of the

shell of freshwater mussels. These laminations are incrementally laid down over the

life of the animal and the metals are believed to remain in situ. Some Australian

mussel species live for more than 30 years. It was proposed that mussels from the


Finniss River be sampled to measure changes in the bioavailable concentration of

metals in the river following remediation.

Methodology

Mussels were sought in the banks of pools and in streambeds using hands and feet

to feel for the animals. The collected animals were aged by a count of the annual

shell rings under transmitted light by Dr Chris Humphrey from Environmental

Research Institute of the Supervising Scientist (eriss). We also acknowledge his

assistance in collection of the mussels and in providing expert advice on the biology

of the species. The soft tissues of the mussels were digested and analysed for

metals to compare with a survey carried out in 1981 (prior to rehabilitated site

remediation) by Alison and Simpson (1989) at several identified sampling sites.

These analyses would also identify those individual mussels most likely to produce

significant results in the SIMS analysis.


In 1995, thirty samples of the fresh water mussel, Velesunio angasi, were collected

from the East Branch upstream of Rum Jungle, from a billabong adjacent to the main

Finniss River upstream of the confluence and below the confluence from three sites.

These downstream sites comprise two off-channel billabongs, that are approximately

one and six km downstream respectively, and a main-channel billabong 14 km

downstream, proximal to our main river site, FR2. Despite assiduous searching by

several people, including Dr Humphrey, no animals could be found closer to the

confluence or within the East Branch below Rum Jungle.

Preliminary assessments on mussels from the sampling sites have shown very

encouraging results from the SIMS analysis (Figures 7.10 and 7.11).


Distance through shell (µm)

0 200 400 600 800 1000 1200 1400

Cu/

Ca

ratio

(x 1

04 )

40

50

60

70

80

90

100

110

120

130

140

150

16019951986

Figure 7.10 Background Cu/Ca signal from a shell collected in the East Branch upstream ofthe former mine site.

Distance through shell (µm)

0 200 400 600 800 1000 1200 1400 1600

Cu/

Ca

ratio

(x 1

04 )

50

60

70

80

90

100

110

120

130

140

19951985

Figure 7.11 Declining Cu/Ca signal in a mussel shell collected in the Finniss River ≈≈≈≈ 14 kmdownstream of the East Branch confluence


In both figures, the copper signal has been expressed as a ratio of the calcium signal

in the same region of the shell. This was to normalise the signal for changes in the

physiology of individual mussels through time, as well as to account for matrix effects

on the analysis technique. In short, this normalising procedure gave a much more

stable response than by using copper alone.

The results for samples from the East Branch above Rum Jungle showed a

consistent signal over the width of the shell ranging between a ratio of 50 to 80 x 10-4

(Figure 7.10). This was consistent with other background signals we have measured

to date and encompassed a period of nine years (the age of the mussel) prior to the

sampling date in 1995.

In comparison, transects across the depth of shell of a ten year old sample from the

main river, 14 km downstream of the confluence of the East Branch with the Finniss

River, showed a consistent pattern of decreasing copper levels from 1985 to

background levels by about half way through the shell (Figure 7.11). Shell

laminations vary in their thickness to some degree.

At first estimate, these results would imply that biologically available copper levels at

this point in the river were at background levels by about 1989. It must be stressed

that these results are preliminary, but they are at the same time very encouraging.

There has been some discussion about the various factors that may affect the

distribution of mussels throughout the system. It was generally concluded that, within

the East Branch, the lack of mussels downstream of Rum Jungle was directly related

to acid levels as well as to the associated metal pollution. Mussels are readily found

above Rum Jungle and in sidestreams.

However, in the main river, the reasons for a lack of mussels below the East Branch

confluence were less clear. Dr Humphrey, who has worked with freshwater mussels

for some time, has suggested that the dense riparian vegetation in this stretch of the

river may reduce primary productivity to a point where mussels cannot survive due to

a lack of food. In support of this hypothesis, downstream mussels have only been

found in billabongs away from the main channel, and it’s associated overshadowing


vegetation, or in larger and more open main channel pools that start occurring well

below the confluence. (This may also have been a confounding influence on the

reduction in Atyid shrimp mentioned earlier).

Against the hypothesis was more recent sampling that did not find any mussels at

some open waterbodies closer to Rum Jungle, that large numbers of intact, joined

shell sets (indicating that the dead mussels had not been transported very far) on the

bank of the river just upstream of the confluence, and also that mussels have been

found (at admittedly lower abundance) in upstream pools with reasonably heavy

riparian vegetation. Another hypothesis is that the water quality (at times during the

year) is toxic to the animals in much the same way as in the East Branch. One

further effect may be the sediment metal loads, which are expanded upon below.

Sediment samples were collected from sites at which mussels had been taken. The

results of chemical analyses on these samples showed that at control sites above

Rum Jungle and in the main river above the confluence with the East Branch, levels

for all metals were of no ecotoxicological concern (Table 7.4). However, below the

confluence, levels of nickel, copper and zinc greatly exceeded values considered

harmful in the upcoming revision of the ANZECC and ARMCANZ environmental

quality guidelines (2001). Similar patterns of contamination were observed for cobalt

and uranium and to a lesser extent for iron. Manganese, cadmium and barium had

little or no consistent sediment distribution patterns.


Table 7.4 Metals in sediments from the Finniss River (µµµµg/g DW).

-18 101 5 5 17 lld 0.05 58 16 4 5454

-0.2 230 11 5 30 lld 0.04 65 15 2 9221EB aboverehabilitatedsite

201 7 3 33 lld 0.30 77 10 3 4326

11 551 202 98 404 112 0.22 58 37 17 10510

8 209 193 191 1061 1748 0.35 84 138 45 8426

4 582 269 371 3643 1896 0.30 76 127 129 12284

SQG-low nd nd 21 65 200 1.5 nd 50 nd nd

SQG-high nd nd 52 270 410 10.0 nd 220 nd nd

NB: nd = no data. lld = less than the detection limit.

The Sediment Quality Guidelines (SQG) levels were sourced from ANZECC and ARMCANZ(2001). Below SQG-low there is a low probability of biological effect, above SQG-high there is ahigh probability of biological effect.

Adult mussels are filter feeders, not detritivores, and therefore they are generally

exposed to metals dissolved in the water column and associated with suspended

particles rather than to metals in interstitial waters and associated sediment.

However, young mussels, called glochidia, are so small when they drop onto the

substrate from fish gills that they are possibly exposed to the interstitial waters in the

microlayer immediately adjacent to the sediment surface. From this, it is

hypothesised that juvenile mussels may not be able to recruit into the pools

immediately downstream of the East Branch confluence because the high metal

levels in sediment are giving rise to toxic metal concentrations in the interstitial

water. Adult mussels are sedentary, and hence, unable to migrate into these areas

after settling.

Despite finding many mussels at a point approximately 11 km downstream of the

East Branch confluence in 1996, none of these mussels was older than six years.

Older mussels do occur in sites both downstream and upstream of the East Branch

confluence. Assuming the above hypothesis to be true, this observation, in

conjunction with the reduced copper signal observed in the SIMS analysis of shells,

suggested that the environmental quality of the river at this point became tolerable

Distance fromEB (km)

Mn(µµµµg/gDW)

Co(µµµµg/gDW)

Ni(µµµµg/gDW)

Cu(µµµµg/gDW)

Zn(µµµµg/gDW)

Cd(µµµµg/gDW)

Ba(µµµµg/gDW

Pb(µµµµg/gDW

U(µµµµg/gDW

Fe(µµµµg/gDW


for glochidia by approximately 1990. This implication was very encouraging in terms

of the success of the remediation in that it suggested that there has been a

secondary or flow-on improvement in habitat quality for a factor (river sediment

quality) not addressed in the specific aims of the project.

Chemical analyses for metals in soft tissue taken from mussel samples collected

during the first survey were completed. The average copper concentrations in those

tissues at each of the sites sampled are shown in Figure 12. Several other metals,

namely calcium, manganese, barium, iron, magnesium, zinc, sodium, cobalt,

strontium, cadmium, mercury, uranium, potassium, arsenic, nickel, lead and

selenium were also included in the analyses and generally showed a similar pattern

between sites, with some exceptions. The copper results from the 1981 survey

(Alison and Simpson 1989), which included fewer metals, were included for

comparison with the more recent values.

Site FR6

FR6

'bon

g

EB8

FR5

'bon

g

FR3

'bon

g

FR4

'bon

g

FR2

Cu

(mg.

kg-1

DW

)

0

10

20

30

40

50

60

1981 Alison & Simpson1995 This study

Figure 7.12 Average copper concentrations in soft tissues of mussels collected 1981 and1995

The data show that where comparable information exists, tissue concentrations of

metals were typically less at all sites in 1995 compared with 1981. There are several

hypotheses to explain these results. Firstly, it may have been an artefact of analytical

technique. Secondly, the environmental levels of metals may have dropped at all


sites in the intervening period between sample surveys and thirdly, it may have been

an artefact of sampling.

The first hypothesis was rejected because there was sufficient detail in the previous

report (Alison and Simpson 1989) to suggest that adequate quality control had been

employed to avoid systematic error of the type indicated.

The second hypothesis was rejected as the sole reason for the observed decline

because the reduction was observed at all sites, not just those downstream of Rum

Jungle, as would be expected if the reduction were due to Rum Jungle remediation.

Nonetheless, it may be that this process may explain a proportion of the apparent

reduction at some sites.

The third hypothesis was the most likely. Mussels will accumulate a range of metals

within relatively insoluble granules, mainly consisting of calcium phosphate, that are

continually being produced within the soft tissues of the animal throughout its life.

Thus, if the animals collected in 1981 were older than those collected at the same

sites in 1994, then they would tend to have higher concentrations of all metals in

their tissues. The calcium results tend to confirm this hypothesis (Figure 7.13).

From the soft tissue analyses it can be noted that there was no consistent pattern of

metal contamination that can be directly related to impact from Rum Jungle.

However, this observation was confounded by the deficient number of mussels found

at various sites within the main river. Additional mussels found during the most

recent field trip and awaiting analysis will hopefully provide more information on this

subject. In proposed work, it is suggested that translocation of adult mussels into

sites closer to Rum Jungle will provide relevant data, at least in terms of assessing

bioavailable metals, by the metal signatures laid down sequentially in shell

laminations.


Site FR6

FR6

'bon

g

EB8

FR5

'bon

g

FR3

'bon

g

FR4

'bon

g

FR2

Ca

(mg.

kg-1

DW

)

0

10000

20000

30000

40000

50000

1981 Allison & Simpson1995 This study

Figure 7.13 Calcium concentrations in soft tissues of mussels from sites within the FinnissRiver catchment

7.6. FIRST FLUSH ASSESSMENT

Background

In the pre-rehabilitation biological survey (Jeffree and Williams, 1975) the major

incident causing obvious detriment to the aquatic ecology was the first flow of

contaminated water from Rum Jungle along the entire length of the East Branch and

into the main Finniss River. The impact was most marked when the flow from the

East Branch corresponded with relatively low flow in the main river. Under these

circumstances, high metal concentrations were measured and large fish-kills were

observed in the main river. In addition, small fish that entered the East Branch from

side-streams were seen to die almost immediately. Comparative biological samples

taken from affected areas of the Finniss River before and after the first flush events

over two years showed reductions in the diversity and abundance of species caught

at that time.


Introduction

It is postulated that high levels of toxic metals were built up in the bed of the East

Branch over the dry season as a result of precipitation and evaporative concentration

of solutes in the recessional flow from Rum Jungle, predominantly comprising

seepage from the Heaps. This pollutant load was then picked up by the first flush

down the East Branch to produce the toxic effects observed at that time.

The basic physical processes, linked to the climatic conditions, remain unaltered to

the present time. Hence we would anticipate that the first flush would remain a major

ecological event within the annual cycle in the East Branch and Finniss River, and

this would also be true for the ecotoxicological impacts. Some of the survey results

presented earlier in this report support this contention. To assess that possibility, an

attempt to monitor the first flush was undertaken over the period comprising the start

of the 1997/1998 wet season.

Aims and constraints on the study

The study was designed to monitor chemical and biological parameters along the

East Branch and in the main Finniss River prior to and during the initiation of flow

along the length of the East Branch. This was achieved by collection and analysis of

water samples, measurement of physicochemical water quality parameters and

sampling and subsequent identification and enumeration of stream biology using

observation, dip netting and trapping. The variable nature of the environment was a

constraint on the study, because access to the sites was more difficult, and in some

cases impossible, following the onset of rains.

Methods

Basic biological, water sampling and physicochemical measurement methods were

the same as those detailed earlier for the decapod surveys. The only substantial

difference was the opportunistic nature of the sampling protocol and the variation in

the catch effort applied. Often several sites were visited on the same day so the

number of traps set and habitats dip netted was necessarily reduced at these times.

At other times, some sites were inaccessible due to the prevailing weather, river


and/or road conditions. In addition to the normal sampling and measurements,

observations were made of the behaviour or condition of any animals that could be

seen during the time available at each site.

Chemical analyses by the Water Resources Division of the former NT DLPE

comprised AAS for the major cations: sodium; potassium; calcium; and magnesium,

alkalinity titrations, metering of conductivity and pH and analyses of the following

major anions: sulfate; chloride; and bicarbonate. These analyses were performed on

unfiltered one litre samples that had been kept chilled since sampling.

For trace metal analysis the samples were freighted to LHRL. The samples were

microwave digested and then analysed using either ICPAES (ANSTO Method VEC-

I-9-03-002) or ICPMS (ANSTO Method VEC-I-9-03-003) depending upon metal

concentration. These analyses were performed on acidified (<pH 2), filtered and

unfiltered samples.


Flow and water quality

At the beginning of the period of observation the system was very dry and several of

the sites had no standing water. Monitoring of these sites was thus not possible.

Some early rain events did affect various sites and in some cases induced

movement of water downstream. However, these early rains did not establish flow

along the length of the East Branch. The rains that finally initiated the first flush fell

on the 23 to 27 December 1997. Minimal flow from the East Branch into the main

river occurred on 27 December and this low flow along the length of the East Branch

persisted on 28 December. The East Branch out-flow was observed to be slowly

increasing on 30 December. Flow in the Finniss River was high on 2 January to the

extent that there was back-up into the East Branch by about 100 m and the river

level had increased significantly at all sites. However, by 10 January the flow in the

Finniss River above East Branch was reduced substantially and East Branch was

contributing much of the flow in the river downstream of the confluence.


With reference to the water quality, the measurements made at all sites were

influenced by local rainfall and run-off from time to time before the establishment of

flow in the East Branch. The concentrations of copper at various sites downstream of

Rum Jungle over the entire period of sampling are shown in Figure 7.14. Similar,

although not identical, patterns were observed for all metals.

These showed an interesting pattern that varies with distance downstream of Rum

Jungle. For the most contaminated site (EB6) just downstream of the Heaps and

open cut outfall, initial concentrations were extremely high and the effect of rain in

the area was simply to dilute these high values (Figure 7.14a). The implication of this

observation was that the pollution at this site was due to evaporative concentration of

recessional flow seepage. There was no indication of any substantial additional load

from somewhere on Rum Jungles after initiation of rainfall over the period of

observation. Flow through the open cuts began on 2 January (M. Lawton, NT DIPE,

pers. comm.) and continued over the period of observation. This needs to be viewed

with caution as we were only looking at concentrations as distinct from loads at this

stage. However, the observation was consistent with the interpretation that the onset

of rains served only to dilute and flush out the extremely high levels of metallic

contaminants from this region of the East Branch.

Towards the GS 8150097 at Site EB4, approximately half the distance to the main

river, the pattern changed (Figure 7.14b). There were relatively low concentrations of

metals prior to the first flush. These values were seen to increase, reasonably due to

discontinuous flow from the more heavily contaminated sites closer to Rum Jungle.

After initiation of competent flow along the length of the East Branch the

concentrations gradually decreased. It should be noted that even the lowest values

measured were still extremely high compared to the current ANZECC (1992)

guidelines.

Towards the confluence with the main river, the East Branch was influenced by the

presence of a small spring (Hanna’s Spring) that continues to flow for a considerable

period of time each year after the East Branch stops flowing along its length. The

initial metal concentrations were thus much reduced at these sites (Figure 7.14c),

compared with those upstream, but not in comparison with the ANZECC guidelines.


At these sites, it was the initiation of the first flush that brought about the maximum

concentrations observed. Subsequent levels were diluted.

a.

0

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Figure 7.14 Concentration of copper in filtered water from the East Branch and the FinnissRiver over the period that water began to flow down the East Branch in 1997.

(a – Sites EB 8 and 6; b – Sites EB 5 and 4; c – Sites EB 3 and 2, and; d – Sites FR 4 and 3)


After the initiation of competent flow along the length of the East Branch on 27

December until at least 16 January, the copper concentrations show very little

dilution from site EB5 to EB1. This result implied that the water from the catchment

downstream of Rum Jungle was contributing relatively little to the overall flow in the

East Branch at that time. Hence, observations of biological detriment at sites

downstream of Rum Jungle, given later in this report, represent a worst case

scenario for this section of the system.

In the main river, the observations were generally restricted to those downstream

sites closest to the confluence with the East Branch (Figure 7.14d). The

concentrations of all metals increased to local maxima on 27 or 29 December

coinciding with the earliest flows out of the East Branch. There was also evidence of

some of the contaminated water flowing upstream into FR5, the site immediately

upstream of the East Branch confluence. Comparing the copper concentrations in

the sites downstream of the confluence with those measured in the East Branch on

the same day indicated that the effective dilution at the confluence was a factor of

about ten.

On 10 January, the differential nature of the flow in the East Branch compared to the

main river resulted in high metal concentrations occurring. These conditions were the

most critical in terms of the likelihood of acute biological impact in the main river. The

apparent dilution at that time was only a factor of about three. Measured

concentrations of metals in the main river sites at that time are given in Table 7.5.

Table 7.5 Maximum measured concentrations of heavy metals in filtered water samples(µµµµg/L) in sites downstream of the East Branch confluence in January 1998subsequent to the first flush in December 1997.

NB: The ANZECC (1992) water quality guideline values for protection of freshwater ecosystems areincluded for comparison

Site Distance fromEB confluence

Mn (µµµµg/L) Co (µµµµg/L) Ni (µµµµg/L) Cu (µµµµg/L) Zn (µµµµg/L)

FR4 1.2 km 502 98 82 155 301FR3 2.5 km 396 84 75 120 134

ANZECC 1992 guideline values 15-150 2-5 5-50


The maximum copper and zinc values were well above the guideline values whilst

nickel was within a range for concern. It should be noted that the average values

over the entire period of flow were less than these concentrations.

Biology

There were logistical problems for the biological sampling over the entire period that

will make quantitative evaluation difficult. These included: limitation of access to

sites; changing water clarity to obscure direct observation; changing water levels that

influenced sampling habitat; changing flow that influenced a range of factors from

animal behavior to catch efficiency; and loss of sampling devices as a result of

altered physical conditions at the various sites. Nonetheless, some qualitative

evaluation of the data can be made, particularly with reference to the pre-

rehabilitation observations made by Jeffree and Williams (1975).

On the day of the first flush, fish were seen to enter the East Branch from the Finniss

River and there was some exchange of fish between the lower sections of East

Branch and its side-streams. No life was observed in the upper sections of East

Branch below Rum Jungle. This pattern was consistent on 28 December but by this

time there had also been mortality of both fish and crustaceans within the lower

reaches of the East Branch. On 30 December, no life was observed at any East

Branch site even though the water was described as being clear at all sites except

EB6. Live fish were observed at two sites in the East Branch on 31 December.

These sites were near sidestreams that were potential replenishment sources of

healthy fish. These observations were also consistent with the opportunistic notes

made of the previous years event (see last paragraph in section 7.3 of this report on

decapod surveys in the East Branch). In general, the degree of biological response

observed during the most recent study was less critical than that observed by Jeffree

and Williams (1975) who observed fish being adversely affected immediately upon

entering the East Branch from side streams.

No living fish were observed in the East Branch over January although observations

were hampered by access and water clarity. The only biological sample collected

over this period was a small dead catfish. This species is known to be migratory at

this time and its genera are also to be tolerant of poor physicochemical conditions


(Burggren and Cameron, 1980; Hughes et al. 1992). However, they are known to be

sensitive to metal toxicity (Jeffree and Twining, 1998).

In the main river, the only evidence of biological impact was the collection of some

dead Atyids at FR4 on 30 December and the absence of these shrimp in subsequent

observations. However, the sampling was hampered by access and site variability

over this time. During the same period, fish were observed behaving normally and

larger decapod crustaceans were collected alive in traps downstream of the East

Branch confluence with the main river.

The main river observations were consistent with the survey results from previous

years. That is, fish diversity and abundance had recovered significantly in the

previously impacted zone of the river (Jeffree and Twining, 1998) and Atyids were

indicated as being the most sensitive decapods to metal toxicity. In comparison with

the earlier work of Jeffree and Williams (1975), no fishkills were observed in Finniss

River during the recent survey. This is surprising given that the flow into the river on

10 January was predominantly from the East Branch as noted by observation and by

the concentration of metals at that time, and that the measured values were well

above ANZECC guideline values (Table 7.5). However, factors such as the levels of

suspended solids, other dissolved salts and the probable presence of relatively high

levels of dissolved organic compounds, as a result of surface run-off carrying leaf-

litter and other material from the adjacent land that had built up over the dry season,

would reduce the toxic, bioavailable proportion of these metals in water. There is

also the possibility that adaptive tolerance has been developed in these populations

due to the extended period over which natural selection may have occurred. This

latter hypothesis is currently being tested at ANSTO.

Conclusions from the observations made of the first flush

On the basis of this initial preliminary assessment, the observations support an

interpretation that the first flush is still a major source of contaminated water to the

East Branch as evidenced by the metal analyses. In addition, this influx has a

marked toxic effect on exposed aquatic animals. Fish kills were observed in the East

Branch and dead crustacea were collected from both the East Branch and Finniss

River during the period following the first flush.


Nonetheless, the degree of ecological impact represents a marked improvement

over what had been observed in the pre-rehabilitation survey. Observations did not

show any adverse effects to fish and larger crustacea in the main river even under

conditions that would be expected to maximise the chances of impact. The previous

field survey of fish (Jeffree and Twining, 1998) corroborates these observations. The

lack of effect was despite metal concentrations being well in excess of the current

water quality guidelines. The biological impact in the East Branch was less intense

than had been observed in the past.

7.7. SYNOPSIS

The ecological studies carried out in the Finniss River within the current 1993-1998

monitoring and maintenance program for Rum Jungle comprised work on three

subjects:

• Benthic and epi-benthic macro-invertebrate sampling to assess the change in

status following remediation and the on-going impact of rehabilitated site run-

off;

• The use of freshwater mussels as archival monitors of bioavailable metals,

particularly copper, in waters downstream of Rum Jungle; and

• A preliminary assessment of the present day impact of the first flush of

polluted water along the East Branch and into the Finniss River.

The major objectives of each of the studies have been met. The studies have shown

clear evidence of on-going impact. The early dry season decapod sampling showed

population declines in the zone of the Finniss River that was previously the most

affected by Rum Jungle pollution and there was still obvious toxic effects on most

biological indices along a strong contaminant gradient within the East Branch. Fish

and crustacean deaths were observed in the East Branch during the first flush. The

lack of mussels in a section of the Finniss River downstream of the East Branch

confluence was also indicative of present day impact.

The current biological assessments were often confounded by the wide natural

variability within the system and through time. However, the recent observations of

detriment that were ascribed to Rum Jungle may well be, to some degree at least,

residual. For example, heavily contaminated sediments persist within the bed of


Finniss River but these levels would be decreasing with time as the system is

flushed with less contaminated water each year. Inconclusive evidence for on-going

improvement includes the recent observation of mussels closer to the East Branch

than in previous years, but to an age of only six years, and the increasing

populations of Atyids noted in sequential years’ surveys.

Nonetheless, each of the investigations have also shown appreciable improvement

in the ecological measures of the Finniss River system compared to the conditions

that existed prior to rehabilitation at Rum Jungle.

The decapod surveys found ecotoxicologically sensitive species within regions of the

river where none were found previously, despite more intensive surveys being

undertaken. This included some recovery within the East Branch that drains Rum

Jungle. There was also evidence for in situ recruitment of juvenile crustaceans within

the impacted zone of the main Finniss River. In addition, despite conditions occurring

that would maximise the likelihood of observing a fish kill in the main river, as

observed prior to rehabilitation (Jeffree and Williams, 1975), fish were observed

swimming and behaving normally. No fish deaths were observed in the main river

during the first flush of the East Branch in the 1997/1998 wet season. This result

supports the previously reported recovery in fish populations in the main river

(Jeffree and Twining, 1998).

The mussel studies have shown a strong decline towards background levels in the

biologically available dissolved copper within the Finniss River. This was evidenced

by the SIMS analysis across the annual shell laminations. However, this result

requires validation by additional analyses and further development of the

measurement technique. (Markich et al. in prep)

Other considerations

Some problems with the general interpretation of our results have arisen due to the

increased development of the catchment and anecdotal evidence of possible

biological impact. One of the landowners reported that, at one of our sites at least,

yabby and fish poaching had occurred. From the degree of impact he described, it is

unlikely that this activity has had a significant effect on the results reported here, but


it needs to be considered in future assessments. In addition, the illegal use of

organo-chlorine pesticides in the upstream catchment of the main Finniss River had

also been suggested. If true, this could have confounding effects, as could other

influences such as eutrophication or enhanced suspended sediments due to

development. However, being aware of the possibility of impact will allow future

sampling strategies to be designed, as far as possible, to compensate for these

effects.

7.8. SUGGESTIONS FOR FURTHER WORK

While it is recognised that the monitoring to date demonstrates the original objectives

have been achieved, it is nevertheless worth exploring other scientific questions in

order to fully understand the site and processes that operate and influence the sites

bio-physical behaviour. As such the following suggestions are made for further

consideration.

From the observations made to date it is apparent that the ecology of the Finniss

River downstream of the Rum Jungle rehabilitated site has improved following

remediation of the site. However, the system lacks stability. The downstream sites

are also subject to possible regression if water quality deteriorates in future. Further,

there is the problem of reconciling the apparent improvement in biological indices

with the national water quality guidelines (ANZECC, 1992; ANZECC and ARMCANZ,

2001). However, as these are the only recognised guidelines available it is pertinent

to reference them considering the measured improvements in the Finniss River were

better than might be expected. The water quality values that have been measured in

the Finniss River regularly exceed the recommended concentrations for the

protection of freshwater ecosystems. Peer criticism is certain to raise this issue in

assessing the outcomes of the rehabilitation process. Hence, the following studies

are suggested for future monitoring and assessment of the impact of the work at the

site. These are in line with the international and national recognition that

rehabilitation of any site impacting on aquatic systems is best measured by biological

indices. Those studies considered to be of highest priority are listed first.


1. Ecological risk assessment and water quality modellingOnce all field data have been collated and reported, the outcomes can be used to

derive a distribution of dose-responses for all taxa measured in the field studies. This

distribution can then be analysed to determine the concentrations of metals in the

environment at which any prescribed proportion of adverse biological response is

likely to occur. The objective is to derive critical values of water quality that are

related to acceptable degrees of ecological impact as agreed between the various

stakeholders, be they the responsible government, regulatory bodies, traditional

landowners or the general public.

The agreed values will then be compared with the measured water qualities

downstream of the site. At present these comprise fairly complete data at

GS 8150097 plus ‘snapshots’ at many other sites based on sampling by ANSTO but

at limited times. Some modelling is required to estimate the likely annual patterns of

exposure at these other sites for adequate evaluation of the severity and extent of

water contamination downstream of Rum Jungle.

A convolution of the probability distribution functions for dose-response and water

quality will finally give the best estimate of the risk that Rum Jungle poses to the

ecology of the Finniss River system, at present, along the length of the river. Given

adequate predictions of future pollutant loads, these risks can also be evaluated for

future conditions.

Macroinvertebrate studies in the main river

Benthic invertebrates have shown (in this and previous reports) their capacity to

monitor effects of acid drainage on aquatic systems. They are also included in the

National Water Quality Management Strategy (ANZECC and ARMCANZ, 2001). It is

crucial to include surveys of these organisms in the main river to complement the

studies carried out in the East Branch that have shown on-going impacts from Rum

Jungle. These data are also required as part of the whole ecosystem approach to

monitoring, mentioned earlier, and will be included in the ERA of the system.


Mussel translocation experiments and sediment ecotoxicology

These studies would:

1. Provide clear evidence of the bioavailable metal concentrations at a number of

sites along the river at increasing distances from Rum Jungle, through time.

Hence, these data would afford a very good index of the geographical extent and

severity of persistent ecological impact from Rum Jungle; and

2. Establish the degree of present day effect due to residual problems manifest by

tailings and other materials present in the river bed sediments.

Benthic algae and bacteria

To complement the suite of taxonomic groups, studies on these organisms are

required for competent appraisal of the overall structural and functional capacity of

the Finniss River ecosystem and for ERA. Algae are an important part of the energy

input to the system and bacteria are crucial for nutrient recycling in the system. Both

taxa also have a role in controlling the bioavailability of toxicants in the water column.

A series of relatively straightforward and cost-effective assays relevant to acid mine

drainage, using field samples of benthic algae and bacteria, have been developed at

ANSTO in collaboration with universities.

For algae, a Fluorescein Diacetate Assay (FDA) assesses the metabolic activity of

algae when exposed to waters collected in the field.

For bacteria from sediments, extraction of phospholipids and subsequent

quantification of Fatty Acid Methyl Esters (FAME) yields quantitative information on

the diversity and abundance of viable microbes in field samples. The Biolog system

also gives diversity and abundance of bacteria, yeasts and fungi in sediment and

water samples. At the same time the analysis gives an index of the functional

capabilities of the microbial community as reflected in their use of numerous (95)

nutrient substrates.


Shrimp translocation experiments, seasonal variation

Shrimp are showing sensitivity to water quality at the present day. However, the

variability of response cannot be correlated with water quality due to inadequate

monitoring. Translocation experiments comprise rapid, whole effluent testing to

provide dose-response information for ecological risk assessment (ERA) procedures

(below). Observation of population parameters at standard sites across a full year

will give evidence of the degree of in situ recovery in relation to changing water

quality.


8. SITE INTEGRITYM KRAATZ

M4K Environmental Consulting, Casuarina, NT.

A NORRINGTONDepartment of Infrastructure, Planning and Environment, Palmerston, NT.

8.1. INTRODUCTION

Qualitative assessments of site integrity continued at Rum Jungle and focused on

weeds, erosion, wildfire, site access and feral animals. A summary of works

undertaken between July 1993 and June 1998 is provided in this chapter, however a

description of some works undertaken after this period is included.

Ongoing management will be required to maintain the integrity of rehabilitated

structures and meet legislative requirements relating to weed and fire control. Longer

term site integrity issues are briefly discussed, as is the need for a radiological

survey both within and downstream of the site. Broader monitoring, management

and land use issues were discussed in Chapter 2.

8.2. WEED MANAGEMENT

Weeds continued to be a major management problem at Rum Jungle. Initial

introduction of some species is thought to have occurred through importation of

contaminated fill material during rehabilitation (Kraatz 1998). Unauthorised vehicle

traffic continues, however, along with wind and animal transport, has undoubtedly

contributed to the spread of other locally prevalent weeds. It is surmised that these

factors have contributed more significantly to the current weed problem at Rum

Jungle than a decline in the vigour of improved pastures, although no quantitative

validation of this can be provided.

Limited but consistent control efforts were successful in the management of some

weeds, however no weed species present at the completion of the previous

monitoring period were fully eradicated. Control efforts were hampered by limited

availability of personnel and equipment, and record wet seasons, which promoted

weed growth and restricted early dry season access to areas of infestation.


The main weeds targeted in the last year of the 1993-1998 monitoring period were

Grader grass, Gamba grass, Hyptis and Sida. Approximately four weeks per year

were spent on weed management at the site over the monitoring period.

Weed management has previously been reported according to the location of weeds

within the site (Kraatz and Applegate 1992, Kraatz 1998). Apart from work targeting

access tracks, however, recent control efforts have been largely targeted at specific

species and it is appropriate to report accordingly.

Weeds present on the site include:

• Mimosa (Mimosa pigra);

• Grader grass (Themeda quadrivalvis);

• Mission grass (Pennisetum polystachion);

• Rattlepod (Crotolaria goreensis);

• Gamba grass (Andropogan gayanus);

• Hyptis (Hyptis sauveolens);

• Sida (Sida acuta); and

• Cobblers Peg (Bidens sp.)

Mimosa and Grader grass are Class A noxious weeds under the Weeds

Management Act 2001 and therefore must be controlled.

Mimosa

While outbreaks of Mimosa were isolated, individual plants can produce vast

numbers of seeds, which remain viable for many years. A systematic control

program is needed to ensure eradication. This should include regular inspection and

control downstream of the site along the East Branch of the Finniss River.

A substantial control effort was undertaken on a Mimosa infestation in the Tailings

Dam drainage system in 1995/1996. While this was largely successful, isolated

plants continued to appear at the western end of the Tailings Dam, which remains

wet for some time into the dry season (Plate 8.1 “A”). Plants have also grown

adjacent to the Tailings Dam and around the perimeter of Whites Open Cut.


Grader grass

Grader grass continued to be of concern and was most prevalent on the Tailings

Dam and Whites Overburden Heap. Frequent slashing prior to seed maturation and

between herbicide applications was determined as the most successful means of

control. This reduces the impact on non-target species, which can become a

problem with more frequent herbicide application. This program was successfully

implemented from 1996/1997 wet season.

In 1997/1998, Whites Overburden Heap, the Tailings Dam and the treatment plant

area were slashed three times. Late rains in April, however, resulted in further

Grader grass growth and seeding. Grader grass is still contained within the

rehabilitation area.


Plate 8.1 Location of a Mimosa infestation and erosion control works conducted on theRum Jungle site

NB: The above photo is as described in the text. For a fully annotated site plan see Figure 2.2. Aerialphotography, NTC 1425, 2000 1:15,000).

A

E GI

C

DH

BF

N


Other weeds

By 1994, Mission grass had rapidly established within the site. While it is relatively

easy to control with the use of herbicide, damage to non-target species and

maintenance of adequate ground cover was an issue. By the end of the monitoring

period, outbreaks of Mission grass and Rattle pod had become uncontrollable.

Gamba grass is widespread throughout the local area outside the site and

established on the Tailings Dam, treatment plant area, Dysons Overburden Heap

and in other isolated patches around the site. Stands of Hyptis and Sida also occur

throughout the site and Cobblers Peg began to appear towards the end of the

monitoring period.

Access tracks

Given the spread of weeds along frequently used tracks, annual applications of

herbicide (“Round-up”) along these tracks were commenced in February/March 1998

(Plate 8.2). Affected areas were then lightly scraped with a loader or bobcat blade to

remove excess vegetation. These areas then doubled as firebreaks. Note that a

grader is not used in order to minimise soil disturbance and the potential for erosion.

While herbicides were originally used as the main method of weed control, by the

end of the 1993-1998 monitoring period, they were only used on access tracks,

drains, graded banks and other areas, which could not be slashed.

Future management

The objectives of a continuing weed management program at the site should be

considered in light of available resources and the practicalities of eradication versus

management. It should be warned, however, that any decreased level of

management would compromise efforts already undertaken.

It is considered that future weed management at the site should include:

• Regular site inspection and identification and eradication of new weed

infestations. Such inspections need to be timed to enable action prior to seed-set;


• Eradication of Mimosa and Grader grass; and

• Management or containment of other weed species for which eradication is not

considered feasible.

8.3. EROSION CONTROL

Erosion control at the site continued to focus on rehabilitated structures and access

tracks. Despite record wet seasons, minimal erosion control work was required.

Approximately two days a year were spent on erosion control throughout the

monitoring period. Work was undertaken on Whites Overburden Heap, Dysons Open

Cut landform and access track, the Tailings Dam and along the site’s southwestern

access track.

Annual inspections of rehabilitated surfaces and drains and access tracks should be

continued and any erosion repaired as soon as possible.


Plate 8.2 The location of annual herbicide applications along access tracks in the RumJungle site

NB: Herbicide is applied in February/March of each year. The areas are then lightly scraped with aloader or bobcat to remove excess vegetation. For a fully annotated site plan see Figure 2.2. (Aerialphotography NTC 1425, 2000 1:15,000)

Whites overburden heap

Existing soil conservation banks were repaired and additional banks were

constructed along the access track to the top of Whites Overburden Heap in 1995

N


(Plate 8.1 “B”). A record wet season in 1996/1997 led to some damage, which was

later repaired.

Dysons open cut landform and overburden heap

As a result of scouring, the main access track into Dysons Open Cut was closed

(Plate 8.1 “C”), rehabilitated and an alternative, more appropriately located track was

established in 1993. Minor damage to the new access track from the 1996/1997 wet

season was repaired in the 1997 dry season.

Areas of dieback on Dysons Open Cut that were noted by Kraatz (1998) continued to

grow slowly (Plate 8.1 “D”). An investigation was undertaken and is reported in

Chapter 5. Additional soil conservation works were installed in late 1993 to minimise

soil loss from the affected areas. This included the construction of additional contour

banks feeding into a new extension of the main drain. In order to prevent further

disturbance to the exposed clay layer, riprap was placed on top of (rather than keyed

into) the clay surface at critical points. Whilst this is not usual soil conservation

practice, it appears to have successfully prevented further erosion. Further

maintenance of these contour banks will be required to ensure continued erosion

control in the future.

Rollover banks were constructed on the track on the northern edge of Dysons Open

Cut in 1999 following completion of the monitoring period.

Tailings dam

A gully feeding into the southern edge of the Tailings Dam was stabilised by a rock-

lined flume, constructed in the course of a flume design workshop undertaken by

Departmental officers in September 1997 (Plate 8.1 “E”).

Access tracks

The 1996/1997 record wet season caused scour on the site’s southwestern site

access track and rollover banks were constructed (Plate 8.1 “F”). Following another

record season in 1997/1998, additional banks were installed. Further maintenance


was required at the completion of the monitoring period, particularly in the vicinity of

the creek crossing. This will also require ongoing maintenance in the future.

Banks were installed across the track to the north of Whites Open Cut in 1999 (Plate

8.1 “G”).

Other

At the completion of the monitoring period, two other areas of scour were identified

and will require further monitoring. One of these is to the east of Whites Open Cut

(Plate 8.1 “H”), while the second lies to the north of the treatment plant area (Plate

8.1 “I”).

8.4. SITE ACCESS

Rum Jungle is a Restricted Use Area under the Soil Conservation and Land

Utilisation Act 1978 and access to the site is prohibited except in accordance with

formal, conditional authorisations from the Department of Infrastructure, Planning

and Environment. The need for this arose from recommendations of the Site

Management Plan that no activity should be permitted which could “accelerate the

removal of soil covers and the renewed release of containment material” (Verhoeven

1988:3.1).

Whilst access to the site is theoretically restricted, continuing vandalism to fences,

gates and signage means that some traffic continues to access the site. Although

this has not led to significant breakdown of soil conservation works, the restriction of

long term impacts cannot be guaranteed.

Development of Browns deposit (discussed in Chapter 2) may provide a solution

through the blocking of some existing access points and a continual presence both

adjacent to, and/or within the site. Should this not eventuate, further work will be

required to monitor the impacts of traffic.


8.5. WILDFIRES

The maintenance of firebreaks and the annual burning of buffer zones around the

site perimeter continued to be of a high priority and was a requirement under the

Bushfires Act.

Internal firebreaks around pastured areas were re-instated in early 1996 and a four

metre firebreak on the inside of the northwestern corner of perimeter fence was

established in late 1997. This firebreak was sprayed with herbicide early in the 1998

and 1999 dry seasons to enable controlled burning.

Despite this, a wild fire originating outside the site jumped a creek and firebreak and

resulted in the destruction of pastures on Dysons Overburden Heap and Open Cut

and the treatment plant and Tailings Dam areas. Firebreaks in these areas were thus

extended the following season.

Fires were deliberately lit within the site in 1994 and 1996 resulting in the burning of

pastures within Whites North and the copper Heap leach area. It appeared that both

areas recovered well with apparently little effect on the presence and abundance of

species.

A late wildfire in the 1997 dry season climbed Dysons Overburden Heap and

resulted in the burning of all of Dysons Heap and Open Cut and half of the treatment

plant area. New firebreaks were constructed in the north-east corner of the site that

was treated with herbicide to allow for early controlled burns.

A wildfire in 2000 burnt all of Whites North and Whites Overburden Heaps.

Annual controlled burns have been conducted around mid-April in the areas

indicated on Plate 8.3. Fire breaks must continue to be maintained and annual burns

of perimeter buffer zones undertaken.


8.6. FERAL ANIMALS

Feral pigs continued to be prevalent on the site, but caused no significant damage to

rehabilitated areas. Damage to fencing and the movement of pig shooters is possibly

of more concern than the animals themselves.

Control of feral pigs was not considered to be feasible given the difficulty in fully

fencing the site and the range over which these animals forage.

8.7. LONGER TERM SITE INTEGRITY ISSUES

Longer term issues such as the persistence of improved pastures and the

implications of potential colonisation by native tree and shrub species has not been

addressed in any detail since the initial monitoring program of 1986-1988 (Ryan

1992).

A more detailed assessment of the longer term persistence of improved pastures

and stability of erosion control works will need to be undertaken in the future, in the

context of broader monitoring, management and land use issues discussed in

Chapter 2.

Discussions regarding future management and final land use should be conducted

with the benefit of a radiological survey both within and downstream of the site and

within the context of broader monitoring, management and land use issues

discussed in Chapter 2.


Plate 8.3 The location of annual controlled burns undertaken around mid-April on the RumJungle site.

NB: For a fully annotated site plan see Figure 2.2. (Aerial photography NTC 1425, 2000 1:15,000)

8.8. RADIOLOGICAL STATUS

Whilst not strictly a site integrity issue, a brief discussion of the radiological status of

the Rum Jungle site is warranted.

N


Studies undertaken after rehabilitation concluded that radiation from the main source

at the site (the Old Tailings Dam) was below the requirements of the Code of

Practice on Radiation Protection in the Mining and Milling of Radioactive Ores

(AGPS 1982). The code applies “only to areas disturbed by man…and specifically

excludes doses due to natural radiation (other than those arising from the mining and

milling of radioactive ores) from the assessment of compliance with the Code” (Allen

and Verhoeven 1986:12.4). It was therefore not possible to make an absolute

statement about the degree to which rehabilitation met the radiation objective. Allen

and Verhoeven (1986) noted that other natural sources of radiation at Rum Jungle

did not come within the provisions of the Code of Practice.

Davy (1975) determined that radiation levels downstream of the site, prior to

rehabilitation would only exceed acceptable limits for human exposure if a person

drank water from the river and lived solely on food gathered in the vicinity of the river

for a period of 50 years. Hewson (1984) made a recommendation that radiological

survey and sediment sampling downstream of the site is conducted in tandem with

the repeat biological survey of the Finniss River system in 1993. This

recommendation was not adopted in the 1988 Site Management Plan (Verhoeven).

However, it may now be appropriate for a survey to be undertaken both on site and

downstream of the site prior to any significant decision regarding site use and

management.

8.9. RECOMMENDATIONS

The site is currently Vacant Crown Land and subject to Northern Territory legislation.

The management of fire and weeds on the site is not only a legislative requirement

under the Weeds Act and Bushfires Act, it is also paramount to the maintenance of

the site integrity.

Irrespective of future land use or change in tenure, the land owners will need to meet

statutory responsibilities in relation to weed and fire management.


The Committee recommends that a:

• Weed management program continues to include:

- Regular site inspection and identification and eradication of new weed

infestations;

- Eradication of Mimosa and Grader grass; and

- Containment of other weed species for which eradication is not considered

feasible;

• Firebreaks are maintained and annual fuel reduction is conducted subject to

advice from the Bushfires Council;and

• The Restricted Use Area provisions apply while the site remains Vacant Crown

Land and vehicle access to the site is restricted.

In addition the Committee suggests that;

• Annual inspections are undertaken and repair any erosion to rehabilitated

surfaces, drains and access tracks; and

• A more detailed assessment of the longer-term persistence of improved pastures

and stability of erosion control works is undertaken within the context of broader

monitoring, management and land use issues affecting the site. Depending on the

evolution of these issues, it is suggested that this assessment be undertaken by

2009, 25 years following the commencement of rehabilitation.


9. References

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Alison, H and Simpson RD (1989). Element concentrations in the fresh watermussel, Velesunio angasi, in the Alligator Rivers Region. Technical Memorandum25. Supervising Scientist for the Alligator Rivers Region, Canberra.ANZECC and ARMCANZ (2001). National Water Quality Management Strategy.Australian guidelines for water quality monitoring and reporting. Australian and NewZealand Environment and Conservation Council and the Agriculture and ResourceManagement Council of Australia and New Zealand, Canberra.ANZECC (1992). Australian water quality guidelines for fresh and marine waters.Australian and New Zealand Environment and Conservation Council secretariat.Government Printing Office, Canberra.Australian Government Publishing Service (1982), Code of Practice on theManagement of Radioactive Waste from the Mining and Milling of Radioactive Ores.Guidelines.Baes C and Mesmer R (1976). The Hydrolysis of Cations. John Wiley and Sons,New York.Baver LD, Gardner WH and Gardner WR (1972), Soil Physics, 4th Ed, John Wileyand Sons, New York, p234-5.Bell MA (1986) Soil immobilisation and plant toxicity of arsenic, copper and nickelPhD thesis. The University of Queensland.Bennett JW and Gibson DK (1992). Measurement of air permeability of irrigatedcopper ore, Australian Nuclear Science and Technology Organisation,ANSTO/C251.Bennett JW, Harries JR and Ritchie AIM (1989). “A Report to the Northern TerritoryPower and Water Authority on Chemical Activity and Water Balance of theOverburden Heaps at Rum Jungle”, ANSTO/C84.Bruce RC, Warrell LA, Edwards DG and Bell LC (1988). Effects of aluminium andcalcium in the soil solution of acid soils of root elongation of Glycine max cv. Forrest.Australian Journal of Agricultural Research 39:319-338.Burggren WW and Cameron JN (1980). Anaerobic metabolism, gas exchange, andacid-base balance during hypoxic exposure in the channel catfish, Ictaluruspunctatus. J. Exp. Zool., 231(3), 405-416.Cameron RS, Ritchie GSP and Robson AD (1986). Relative toxicities of inorganicaluminium complexes to barley. Soil Science Society of America Journal50:1231-1236.Henkel CHRF (1989) East Finniss River and Finniss River pollution study 1987-1988(Report 75/89D).


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Safety Consultant, NT Department of Health, Occupational and EnvironmentalHealth Branch.Hart H (1974). A compilation of Australian water quality criteria. Rep. No. 7.Australian Water Resources, Canberra.Hewson G (1984), DRAFT Rum Jungle Rehabilitation Project, Radiation SafetyRegime, Department of Transport and Works Northern Territory, Water Division.Hughes GM, Roy PK and Munshi JSD (1992). Morphometric estimation of oxygendiffusing capacity for the air sac in the catfish Heteropneustes fossils. J. Zool.(London), 227(2), 193-209.Jeffree RA and Twining JR (1998). Fish diversity and abundance in the FinnissRiver. Chapter 7 in Monitoring Report 1988-1993, Rum Jungle Rehabilitation Project.Ed. M. Kraatz. TR No. R97/2 Land Resources Division, NT Dept of Lands, Planningand Environment.Jeffree RA and Williams NJ (1975). Biological indications of pollution of the FinnissRiver system, especially fish diversity and abundance. Chapter 7 in ‘Rum JungleEnvironmental Studies’, DR Davy (Ed), Australian Atomic Energy Commission.AAEC/E365 Sept. 1975.Karathanasis AD, Evangelou VP and Tompson YL (1988). Aluminium and ironequilibria in soil solutions and surface waters of acid rehabilitated site watersheds.Journal of Environmental Quality 17:534-543.Khanna P, Prenzel J, Meiwes K, Ulrich B and Matzner E (1987). Dynamics of sulfateretention by acid forest soils in an acidic deposition environment. Soil ScienceSociety of America Journal 51:446-452.Kinraide TB (1991). Identity of the rhizotoxic aluminium species. Plant and Soil134:167-178.Kittrick JA, Fanning DS, and Hossner L.R. (1982). Acid Sulfate Weathering. SoilScience Society of America, Madison, Wisconsin.Kraatz M (Ed.)(1998) Monitoring Report 1988-93, Rum Jungle Rehabilitation Project.Technical Report R97/2, Natural Resources Division, Department of Lands, Planningand Environment.Kraatz M and Applegate RJ (Eds.)(1992) The Rum Jungle Rehabilitation Project,Monitoring Report 1986-88. Technical Report Number 51, Land Conservation Unit,Conservation Commission of the Northern Territory.Lindsay W and Norvell W (1978). Development of a DTPA soil test for zinc, iron,manganese, and copper. Soil Science Society of America Journal 42:421-428.Lindsay WL (1979). Chemical Equilibria in Soils. John Wiley and Sons, New York.Manson AD and Fey MV (1989). Cation type and ionic strength effects on thesolution composition of an acidic subsoil. Journal of Soil Science 40:577-583.Marion GM, Hendricks DM, Dutt GR and Fuller WH (1976). Aluminum and silicasolubility in soils. Soil Science 121:76-85.Markich S.J, Jeffree RA and Burke PJ in prep. Freshwater bivalve shells as archivalindicators of metal pollution from a copper-uranium mine site in tropical Australia.Martell A and Smith R (1976-1989). Critical Stability Constants, Six Volumes.Plenum Press, New York


Menzies NW and Bell LC (1988). Evaluation of the influence of sample preparationand extraction technique on soil solution composition. Australian Journal of SoilResearch 26: 451-464.Menzies NW, Bell LC and Edwards DG (1991). A simple positive pressure apparatusfor the ultra-filtration of soil solution. Communications in Soil Science and PlantAnalysis 22: 137 - 145.Menzies NW, Bell LC and Edwards DG (1994). Exchange and solution phasechemistry of acid, highly weathered soils. II. Investigation of mechanisms controllingaluminium release into solution. Australian Journal of Soil Research 32:269-283.Menzies NW, Edwards DG and Bell LC (1994). Effects of calcium and aluminium inthe soil solution of acid, surface soils on root elongation of mungbean. AustralianJournal of Soil Research 32:721-737.Miller S and Jeffery J (1995). Advances in the prediction of acid generatingrehabilitated site waste materials. In Proceedings of the Second Australian Acidmined drainage Workshop, Grundon, NJ and Bell, L.C. (eds.), Charters Towers,Queensland, pp. 33–42, Australian Centre for Mine site Rehabilitation Research,Brisbane.Minerals Council of Australia (1996), Australian Minerals Industry, Code forEnvironmental Management. Dickson ACT.Morris H (1948). The soluble manganese content of acid soils and its relation to thegrowth and manganese content of sweet clover and lespedeza. Soil Science Societyof America Proceedings 13:362-371.National Health and Medical Research Council/Agriculture and ResourceManagement Council of Australia and new Zealand (NHMRC/ARMCANZ) (2001)Australian Drinking Water GuidelinesNordstrom DK and Ball JW (1986). The geochemical behaviour of aluminium inacidified surface waters. Science 232:54-56.Nordstrom DK and May HM (1989). Aqueous equilibrium data for mononuclearaluminum species. In The Environmental Chemistry of Aluminium, G. Sposito (Ed.),pp. 29–54, CRC Press, Boca Raton, Florida.Padovan A (2001) The Quality of Run-Off and Contaminant Loads to DarwinHarbour. Report No. 29/2000D Resource Management Branch, Natural ResourcesDivision, Department of Lands, Planning and Environment.Parker D, Chaney R, Norvell W and Bell P (1991). ‘GEOCHEM PC Ver 2. Database’.Plenderleith, R (1984). An evaluation of the tolerance of a range of tropical grassesto excessive soil levels of copper and zinc. M.Agr.Sc thesis. University ofQueensland.Rayment G and Verrall K (1980). Soil manganese tests and the comparativetolerance of kikuyu and white clover to manganese toxicity. Tropical Grassland 14:105-114.Reuss J and Johnson D (1986). Acid Deposition and Acidification of Soils andWaters, Springer-Verlag, New York.Richards RJ, Applegate RJ, Ritchie AIM (1996) “The Rum Jungle RehabilitationProject”. In Environmental Management in the Australian Minerals and Energy


Industries, Principles and Practices edited by DR Mulligan. UNSW Press inassociation with the Australian Minerals and Energy Environment Foundation.Richburg JS and Adams F (1970). Solubility and hydrolysis of aluminium in soilsolutions and saturated paste extracts. Soil Science Society of America Proceedings34:728-734.Risser J and Baker D (1990). Testing soils for toxic metals. In Soil Testing and PlantAnalysis, Westerman, R (Ed.), pp. 277–298, Soil Science Society of America,Madison, Wisconsin.Senate Select Committee on the Mining and Milling of Uranium (1996).Ryan P (1992), “Revegetation, Erosion Control and Cover Stability”, in Kraatz andApplegate (1992): 121-137.Sonneveld C, Voogt S and Dijk P (1977). Methods for the determination of toxiclevels of manganese in glasshouse soils. Plant and Soil 46:487-497.Sposito G and Mattigod SV (1980). GEOCHEM: A computer program for thecalculation of chemical equilibria in soil solutions and other natural water systems.University of California, Riverside, California.Strömberg B., Ph.D. Thesis, Royal Inst. Of Technology, Sweden (1997).Verhoeven TJ (1988) “Site Management Plan” in Kraatz and Applegate (1992): 147-162.Williams NJ, Kool KM and Simpson R D (1991). Copper toxicity to fishes and anextremely sensitive shrimp in relation to a potential Australian tropical mining-wasteseep. Intern. J. Environmental Studies, 38, 165-180.Woodward-Clyde (1994) Rum Jungle – Dyson’s Open Cut soil and vegetationdieback study – Phase 1 Report.Wright RJ and Wright SF (1987). Effects of aluminium and calcium on the growth ofsubterranean clover in Appalachian soils. Soil Science 143:341-348.


APPENDIX ATable A 1 Depth to copper heap leach waste, surface (0–15 cm) soil pH and surface fine

earth fraction.

Site Soil depth pH Fine earth(mm) (%)

Bare sites

RJ 1 520 4.45 35RJ 2 320 3.99 25RJ 3 580 3.89 51RJ 4 560 5.04 49RJ 5 760 4.91 48RJ 6 750 4.80 29T13 710 4.79 53T12 680 4.54 47T21 670 4.68 41T22 720 5.10 33T20 610 4.60 38Avg. 625.5 4.60 40.8

Vegetated sites

RJ 7 830 5.93 42RJ 8 850 6.03 49T14 750 5.26 29T15 800 5.50 39T23 840 5.70 34T24 940 5.70 36Avg. 835 5.69 38.17


Table A 2 The pH and elemental concentration in 1:5 soil: deionised water extracts ofsamples taken from bare and vegetated sites

No. Depth pH Ca Mg K Mn Cu Co Ni Zn Al Scm µM µM µM µM µM µM µM µM µM µM

Bare sitesRJ 1 0-10 4.45 74 682 3 144 1800 43 44 5 19 2945RJ 1 10-20 4.20 256 1705 22 264 3404 81 103 11 102 6554RJ 1 20-25 4.00 507 1872 8 251 3607 82 108 12 423 7819RJ 1 25-30 3.76 889 2236 8 250 4481 93 127 15 1318 11384RJ 1 30-40 3.67 918 2289 6 239 4555 92 131 15 1440 11672RJ 1 40-52 3.29 1300 2588 0 221 5412 99 145 17 2285 14989RJ 1 52-55 4.56 2597 3000 169 761 8583 83 133 23 78 15705

RJ 2 0-10 3.99 100 513 7 71 1342 35 36 4 567 3035RJ 2 10-20 3.79 309 2033 4 181 4478 135 143 13 2646 11907RJ 2 20-25 3.68 1086 2938 3 228 6093 194 205 18 3880 18709RJ 2 25-30 3.46 2478 3475 0 248 6847 224 241 22 4819 24322RJ 2 30-38 3.11 1388 3758 0 203 7099 242 254 22 5536 24904RJ 2 38-47 3.19 5044 4604 87 452 6980 270 302 35 5381 31597

RJ 3 0-10 3.89 218 2199 0 313 2601 220 238 12 1812 9373RJ 3 10-20 3.98 177 1501 1 270 1886 143 148 9 1031 6128RJ 3 20-30 3.94 389 2037 4 330 2729 198 208 12 1566 9173RJ 3 30-40 3.78 520 2670 9 335 3486 272 292 18 2934 13398RJ 3 40-45 3.73 1526 3148 5 335 4209 326 358 22 4119 18755RJ 3 45-55 3.51 1014 3517 2 335 4673 372 425 23 5332 21088

RJ 4 0-10 5.04 526 2103 3 78 0 2 9 3 0 3322RJ 4 10-20 4.64 280 1500 7 164 300 23 52 5 0 2693RJ 4 20-28 4.28 255 1431 12 161 373 32 52 5 45 2661RJ 4 28-45 4.09 516 1488 11 202 465 49 65 6 127 3476RJ 4 45-56 3.22 932 1380 0 211 584 50 67 7 469 4878RJ 4 56-60 3.90 6995 1805 339 1255 695 49 73 15 400 12862

RJ 5 0-10 4.91 35 188 3 16 0 1 6 1 0 262RJ 5 10-20 5.51 49 232 3 1 0 0 1 0 0 284RJ 5 20-30 6.14 90 405 2 0 0 0 0 1 0 511RJ 5 30-36 5.44 210 847 0 10 0 1 8 2 0 1197RJ 5 36-46 4.60 797 1393 8 142 224 30 46 6 37 3278RJ 5 46-76 4.09 1161 1692 10 192 436 51 68 9 107 4628

RJ 6 0-10 4.80 70 417 7 67 144 9 17 2 0 794RJ 6 10-20 5.21 66 363 5 6 0 0 4 1 0 478RJ 6 20-30 6.10 92 458 5 0 0 0 0 1 0 590RJ 6 30-45 6.12 112 403 1 0 0 0 0 1 0 553RJ 6 45-85 4.84 173 291 9 13 0 1 2 1 0 604


Table A 2 The pH and elemental concentration in 1:5 soil: deionised water extracts of samplestaken from bare and vegetated sites

Site No. Depth pH Ca Mg K Mn Cu Co Ni Zn Al Scm µM µM µM µM µM µM µM µM µM µM

Vegetated sitesRJ 7 0-10 5.62 77 417 15 0 0 0 0 -1 0 578RJ 7 10-20 5.93 373 1995 0 1 0 0 0 2 0 2858RJ 7 20-30 6.01 774 3268 0 11 0 0 1 4 0 5547RJ 7 30-40 4.63 800 2532 2 1501 420 90 121 12 1 4520RJ 7 40-45 4.64 421 2203 9 1148 738 102 124 11 1 3914RJ 7 55-75 4.66 579 2404 9 676 291 66 81 8 3 3782RJ 7 75-83 3.98 549 1601 4 66 19 8 11 4 21 2443

RJ 8 0-10 6.03 17 49 0 0 0 0 1 0 7 42RJ 8 10-20 5.88 11 46 0 0 0 0 1 0 0 44RJ 8 20-30 5.79 16 85 0 0 0 0 0 0 0 98RJ 8 30-40 5.25 68 262 4 3 0 0 2 0 0 434RJ 8 40-70 4.64 120 325 6 23 28 5 7 0 0 639RJ 8 70-85 4.08 139 273 6 84 176 13 15 1 33 869

Table A 3 The soil solution pH, EC and elemental concentrations in the surface soil ofTransect 2

pH EC Ca Mg Mn Co Ni Zn Al K S CuSample

dS m-1 mM mM µM µM µM µM µM µM mM µMBareRJ-T 1

4.32 2.340 0.92 4.46 188 423 332 56.03 58.3 37.3 17.4 4041

BareRJ-T 2

4.38 2.000 0.90 4.46 188 274 243 28.38 19.1 28.2 14.3 2069

InterfaceRJ-T 3

4.82 0.650 0.33 1.75 255 10.7 49.1 5.15 1.2 53.0 2.93 6.3

Veg. 3 mRJ-T 4

5.29 0.521 0.33 1.57 1.40 0.5 <0.1 2.14 <0.1 54.1 1.85 <0.1

Veg. 6 mRJ-T 5

6.36 0.501 0.26 1.62 0.64 0.6 <0.1 2.11 <0.1 63.0 2.17 <0.1


Table A 4 The activity of selected ionic species in soil solutions from Transect 2 surfacesamples

Sample Al3+

µMAlOH2+

µMAl(OH)2

+

µMAl(SO4)+

µMAl(SO4)-

µMCu2+

µMCuOH+

µMCuSO4

o

µMBareRJ-T 1 1.08 0.41 0.03 24.0 5.37 1127 0.47 1980

BareRJ-T 2 0.61 0.14 0.03 12.1 2.37 624 0.30 970

InterfaceRJ-T 3 0.01 <0.01 <0.01 0.03 <0.01 1.0 <0.01 1.6

Veg. 3 mRJ-T 4 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01

Veg. 6 mRJ-T 5 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01


Table A 5 Sampling depth, EC, pH and DTPA-extractable metal contents of samples takenfrom bare and vegetated areas

Depth EC pH Cu Mn Zn Co NiNo.

cm µS cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

Bare SitesRJ 1 0-10 526 4.45 504 7 1 10 12RJ 1 10-20 1040 4.20 764 100 2 20 30RJ 1 20-25 1130 4.00 909 100 2 22 32RJ 1 25-30 1530 3.76 1257 100 4 28 38RJ 1 30-40 1600 3.67 1338 99 4 28 40RJ 1 40-52 2050 3.29 1525 90 5 30 43RJ 1 52-55 2070 4.56 1736 65 4 24 37

RJ 2 0-10 504 3.99 412 5 0 8 7RJ 2 10-20 1540 3.79 1296 69 4 41 42RJ 2 20-25 2180 3.68 1714 92 5 57 60RJ 2 25-30 2830 3.46 1916 99 6 68 73RJ 2 30-38 2870 3.11 1984 82 6 71 77RJ 2 38-47 3540 3.19 1714 39 6 69 74

RJ 3 0-10 1270 3.89 688 100 2 54 57RJ 3 10-20 918 3.98 425 67 1 31 33RJ 3 20-30 1250 3.94 743 99 2 49 51RJ 3 30-40 1660 3.78 1016 99 5 78 81RJ 3 40-45 2240 3.73 1197 99 6 94 102RJ 3 45-55 2420 3.51 1254 99 6 103 118

RJ 4 0-10 594 5.04 66 37 1 1 4RJ 4 10-20 511 4.64 276 22 1 8 19RJ 4 20-28 537 4.28 241 42 1 10 19RJ 4 28-45 625 4.09 215 78 2 18 24RJ 4 45-56 939 3.22 67 67 1 7 7RJ 4 56-60 1970 3.90 75 17 0 10 12

RJ 5 0-10 71 4.91 103 26 1 3 9RJ 5 10-20 78 5.51 25 29 0 1 3RJ 5 20-30 125 6.14 20 20 0 0 0RJ 5 30-36 254 5.44 57 20 2 1 8RJ 5 36-46 607 4.60 246 70 3 15 24RJ 5 46-76 852 4.09 218 76 3 19 26

RJ 6 0-10 176 4.80 253 27 1 5 9RJ 6 10-20 113 5.21 136 14 1 1 5RJ 6 20-30 133 6.10 8 8 1 0 1RJ 6 30-45 122 6.12 23 7 0 0 0RJ 6 45-85 122 4.84 26 15 2 2 4


Table A 5 Sampling depth, EC, pH and DTPA-extractable metal contents of samplestaken from bare and vegetated areas (Continued)

Depth EC pH Cu Mn Zn Co NiNo.

cm (S cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

Vegetated SitesRJ 7 10-20 526 5.93 0 27 1 0 0RJ 7 20-30 860 6.01 0 30 1 1 2RJ 7 0-10 109 5.62 6 100 0 1 1RJ 7 30-40 763 4.63 254 16 2 26 32RJ 7 40-45 676 4.64 312 24 2 35 41RJ 7 55-75 651 4.66 271 37 2 26 30RJ 7 75-83 456 3.98 26 16 2 3 4

RJ 8 0-10 25 6.03 0 100 0 0 1RJ 8 10-20 19 5.88 0 56 0 0 0RJ 8 20-30 29 5.79 0 14 0 0 0RJ 8 30-40 74 5.25 50 10 1 1 6RJ 8 40-70 120 4.64 133 14 1 5 8RJ 8 70-85 178 4.08 141 15 0 6 6


Table A 6 Elemental tissue concentrations in grass samples taken from vegetated areas and transects across bare area / vegetation interfacesof Dysons Open Cut and vegetated areas of Whites Dump.

Sample N%

P%

K%

Ca%

Mg%

Namg/kg

Almg/kg

S%

Femg/kg

Mnmg/kg

Znmg/kg

Cumg/kg

Bmg/kg

RJ 7 0.598 0.141 0.250 0.254 0.449 100 73 0.095 163 419 40 13.6 2.3RJ 8 0.582 0.114 0.270 0.278 0.490 1315 90 0.149 155 298 49 15.8 4.4

Transect 1Interface RJ-T 2 0.492 0.034 0.039 0.052 0.058 36 725 0.073 1280 166 25 1307.4 6.2Veg. 3m RJ-T 3 0.430 0.060 0.207 0.126 0.233 55 79 0.129 139 173 24 25.3 1.1Veg. 6m RJ-T 4 0.600 0.099 0.197 0.190 0.338 96 224 0.157 403 295 40 43.8 3.4

Transect 2

Interface RJ-T 3 0.402 0.039 0.062 0.110 0.127 58 916 0.066 2788 557 36 951.2 6.2Veg. 3m RJ-T 4 0.537 0.067 0.129 0.239 0.369 124 261 0.147 605 348 39 87.6 25.2Veg. 6m RJ-T 5 0.639 0.109 0.143 0.265 0.622 116 213 0.147 713 468 84 4.0 5.0

White’s Dump 0.340 0.115 0.148 0.200 0.350 122 143 0.136 246 390 78 6.2 1.5

Note: Ni concentrations were 92, 41 and 5 mg/kg at the bare / vegetated interface of transects, at 6 m in from the interface and at locations RJ 7/8,respectively. Co concentrations were 83, 18 and 9 mg/kg for the same sequence, and Ba concentrations 16, 27 and 69 mg/kg for the same sequence.


Table A 7 The pH and elemental composition of 1:5 soil: deionised water extracts ofsamples taken from transects across bare area / vegetation interfaces

Site Depth pH Ca Mg K Mn Cu Co Ni Zn Al SType No. cm µM µM µM µM µM µM µM µM µM µM

Transect 1

BareRJ-T 1 0-10 4.54 212 1299 1 152 138 26 36 3 6 2189RJ-T 1 10-20 5.12 198 1355 4 24 0 1 12 2 0 1829RJ-T 1 20-30 5.93 312 2255 1 1 0 0 1 3 0 3139RJ-T 1 30-43 4.71 600 2992 4 284 360 105 112 8 4 5790RJ-T 1 43-60 3.96 1487 3335 10 6362 1763 220 206 18 334 8727RJ-T 1 60-68 3.35 715 2780 5 3534 1382 168 160 21 767 7160

InterfaceRJ-T 2 0-10 4.79 209 1430 17 147 0 6 17 3 0 2138RJ-T 2 10-20 5.34 133 1094 4 4 0 0 2 1 0 1370RJ-T 2 20-30 6.03 610 2497 0 4 0 1 1 3 0 3988RJ-T 2 30-43 4.70 916 3253 2 243 337 77 100 9 7 6660RJ-T 2 43-55 3.83 1994 3847 11 5372 2627 240 259 21 1177 12176RJ-T 2 55-70 3.23 1792 4442 0 4968 4842 430 449 31 4185 20576

VegetatedRJ-T 4 0-10 5.26 36 199 25 12 0 1 5 1 0 248RJ-T 4 10-20 5.41 103 673 3 0 0 0 1 1 0 840RJ-T 4 20-30 5.52 26 6 753 3 6 18 26 17 453 2805RJ-T 4 30-40 4.50 26 8 735 3 14 18 26 17 449 4356RJ-T 4 40-48 4.01 626 3056 7 2083 1762 178 184 14 447 6963RJ-T 4 48-75 3.14 1361 3758 0 2782 3780 335 364 27 4504 17833

VegetatedRJ-T 5 0-10 5.50 25 1 723 3 4 18 25 17 442 319RJ-T 5 10-20 5.69 25 2 727 3 5 18 25 17 445 591RJ-T 5 20-30 5.81 25 6 734 3 5 18 25 17 451 2857RJ-T 5 40-50 4.44 27 11 742 4 21 19 27 18 457 6226RJ-T 5 30-40 4.89 825 3268 6 1459 90 69 116 9 1012 5012RJ-T 5 50-80 3.57 1502 3227 3 2958 1776 163 198 17 1062 9444


Table A 8 The pH and elemental composition of 1:5 soil: deionised water extracts ofsamples taken from transects across bare area / vegetation interfaces (continued)

Site Depth pH Ca Mg K Mn Cu Co Ni Zn Al SType No. cm µM µM µM µM µM µM µM µM µM µM

Transect 2



InterfaceRJ-T 3 0-10 5.10 25 1 731 3 5 17 25 17 442 496RJ-T 3 10-20 4.76 25 1 727 3 5 17 25 17 439 801RJ-T 3 20-30 4.67 25 2 735 3 9 18 25 17 443 1676RJ-T 3 30-40 4.46 848 1591 17 2128 998 131 101 11 30 4188RJ-T 3 40-53 4.35 1079 1680 13 2058 1104 135 106 13 56 4703RJ-T 3 53-72 4.14 2088 1778 9 2634 1312 160 122 16 137 6423

VegetatedRJ-T 4 0-10 5.70 25 1 729 3 4 17 25 17 438 395RJ-T 4 10-20 5.72 24 1 724 3 4 17 25 17 436 511RJ-T 4 20-30 5.30 25 2 727 3 4 17 25 17 437 1008RJ-T 4 30-40 4.68 304 1246 17 358 102 37 39 5 5 1901RJ-T 4 40-52 4.49 468 1568 16 797 361 72 58 7 13 2813RJ-T 4 52-73 4.21 291 1386 7 1600 656 116 75 8 73 2918RJ-T 4 73-84 4.07 801 1902 13 6070 1038 223 136 14 205 5142

VegetatedRJ-T 5 0-10 5.70 24 1 724 3 4 17 24 17 434 336RJ-T 5 10-20 5.78 24 1 719 3 4 17 24 17 433 334RJ-T 5 20-30 5.81 99 545 0 0 0 0 0 1 -5 694RJ-T 5 30-40 5.42 187 789 7 4 0 0 3 1 -3 1115RJ-T 5 40-58 4.62 192 710 7 30 31 5 10 2 1 1148RJ-T 5 58-75 4.34 147 595 13 34 60 6 6 1 18 954RJ-T 5 75-94 4.21 199 676 16 40 81 7 8 2 28 1148


Table A 8 Sampling depth, EC, pH and DTPA-extractable metal contents of samples takenfrom transects across bare area / vegetation interfaces

Site Depth EC pH Cu Mn Zn Co NiType No. cm µS cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

Transect 1

BareRJ-T 1 0-10 407 4.54 133 49 1 8 11RJ-T 1 10-20 360 5.12 48 24 1 1 8RJ-T 1 20-30 577 5.93 114 11 1 0 2RJ-T 1 30-43 967 4.71 252 42 2 36 35RJ-T 1 43-60 1330 3.96 551 99 3 59 56RJ-T 1 60-68 1170 3.35 315 99 3 36 32

InterfaceRJ-T 2 0-10 429 4.79 153 84 1 4 8RJ-T 2 10-20 292 5.34 114 25 0 0 1RJ-T 2 20-30 720 6.03 48 20 1 0 1RJ-T 2 30-43 1080 4.70 273 36 2 26 32RJ-T 2 43-55 1710 3.83 842 99 4 64 70RJ-T 2 55-70 2510 3.23 1332 99 7 120 119

VegetatedRJ-T 3 0-10 75 5.26 29 35 1 3 18RJ-T 3 10-20 192 5.41 0 29 0 1 4RJ-T 3 20-30 547 5.52 23 20 1 2 5RJ-T 3 30-40 790 4.50 253 15 1 24 26RJ-T 3 40-48 1100 4.01 417 88 2 35 38RJ-T 3 48-75 2200 3.14 1028 100 6 89 90

VegetatedRJ-T 4 0-10 75 5.50 0 79 1 1 9RJ-T 4 10-20 132 5.69 0 16 0 0 1RJ-T 4 20-30 543 5.81 0 16 1 1 1RJ-T 4 40-50 1000 4.44 302 47 2 28 39RJ-T 4 30-40 811 4.89 237 63 2 22 37RJ-T 4 50-80 1390 3.57 462 100 3 38 44


Table A 8 Sampling depth, EC, pH and DTPA-extractable metal contents of samplestaken from transects across bare area / vegetation interfaces (continued)

Site Depth EC pH Cu Mn Zn Co NiType No. cm µS cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

Transect 2

Bare

RJ-T 1 0-10 382 4.60 397 15 1 19 15RJ-T 1 10-20 351 4.61 370 28 2 20 16RJ-T 1 20-30 463 4.68 339 57 3 30 24RJ-T 1 30-40 472 4.52 267 100 4 41 33RJ-T 1 40-53 644 4.39 225 100 4 34 30RJ-T 1 53-61 555 4.23 185 100 3 23 20

Bare


Interface


Vegetated

RJ-T 4 0-10 98 5.70 0 100 0 1 2RJ-T 4 10-20 118 5.72 0 24 0 0 1RJ-T 4 20-30 220 5.30 38 17 1 2 9RJ-T 4 30-40 370 4.68 224 68 3 22 23RJ-T 4 40-52 527 4.49 269 28 1 32 22RJ-T 4 52-73 541 4.21 290 58 2 39 22RJ-T 4 73-84 875 4.07 291 100 2 57 31

Vegetated

RJ-T 5 0-10 84 5.70 0 71 1 1 1RJ-T 5 10-20 76 5.78 0 22 0 0 0RJ-T 5 20-30 146 5.81 0 9 0 0 0RJ-T 5 30-40 235 5.42 11 8 2 0 3RJ-T 5 40-58 247 4.62 169 18 2 4 9RJ-T 5 58-75 194 4.34 290 13 1 4 4RJ-T 5 75-94 234 4.21 281 10 1 4 4


Table A 9 Depth to copper heap leach waste, pH and NAG pH for selected sites

Site No. Waste depthcm

pH NAG pH

RJ 1 52 4.56 4.55RJ 2 38 3.19 2.86RJ 4 56 3.90 3.32RJ 7 83 4.22 2.92RJ 8 85 4.14 3.37RJ-T 1 4 80 3.88 2.81RJ-T 2 1 61 3.54 3.43RJ-T 2 3 94 3.79 2.55RJ-W 1 2 4.21 2.63RJ-W 2 5 4.03 2.85RJ-W 3 40 4.52 3.31

Table A 10 The pH and elemental composition of 1:5 soil:deionised water extracts ofsamples taken through fresh soil placed in a contour bank

Site Depth pH Ca Mg K Mn Cu Co Ni Zn Al Stype cm µM µM µM µM µM µM µM µM µM µM

RJ-C 0-5 5.76 7 24 11 4 0 0 0 0 756 148RJ-C 5-10 5.62 4 10 0 0 0 0 1 0 46 5RJ-C 10-15 5.58 7 24 0 0 0 0 1 0 0 25RJ-C 15-20 5.70 16 66 0 0 0 0 1 0 0 81RJ-C 20-25 5.66 18 81 0 0 0 0 1 0 0 97RJ-C 25-30 5.34 26 118 2 1 0 1 2 1 0 152RJ-C 30-35 4.74 34 142 2 14 43 3 6 1 0 286RJ-C 35-40 4.49 18 98 0 29 199 6 7 1 0 398RJ-C old surf. 4.58 26 148 0 50 260 8 12 1 0 552

Table A 11 The EC, pH and DTPA-extractable metal content of samples taken through freshsoil placed in a contour bank

Site Depth EC pH Cu Mn Zn Co Nicm S cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

RJ-C 0-5 10 5.76 0 32 0 0 0RJ-C 5-10 7 5.62 0 11 0 0 0RJ-C 10-15 12 5.58 0 10 0 0 0RJ-C 15-20 25 5.70 0 8 0 0 0RJ-C 20-25 30 5.66 0 9 0 0 1RJ-C 25-30 43 5.34 46 9 1 1 7RJ-C 30-35 74 4.74 279 18 1 3 7RJ-C 35-40 95 4.49 336 14 0 3 4RJ-C old surf. 123 4.58 323 18 1 4 6


Table A 12 The pH and elemental composition of 1:5 soil:deionised water extracts ofsamples from adjoining bare and vegetated portions of Whites Dump

Site Depth pH Ca Mg K Mn Cu Co Ni Zn AlType cm µM µM µM µM µM µM µM µM µM µM

Bare

RJ-W 0-2 4.11 282 904 0 42 0 4 4 18 57 1577RJ-W 2+ 4.21 1536 2101 883 116 0 8 9 39 137 6211RJ-W 0-5 4.15 14 21 9 15 0 1 1 1 51 154RJ-W 5+ 4.03 65 828 1326 125 0 2 2 6 243 4642

Vegetated

RJ-W 0-10 4.94 17 37 27 5 0 0 1 1 1 79RJ-W 10-20 4.94 11 46 9 2 0 0 1 1 0 65RJ-W 20-30 5.08 12 54 11 1 0 0 1 0 0 71RJ-W 30-40 4.90 18 68 9 2 0 0 1 1 0 95RJ-W 40+ 4.52 142 588 526 31 0 2 2 2 25 1686

Table A 13 The EC, pH and DTPA-extractable metal content of samples from adjoining bareand vegetated portions of Whites Dump

Site Depth EC pH Cu Mn Zn Co NiType cm (S cm-1 mg/kg mg/kg mg/kg mg/kg mg/kg

Bare

RJ-W 0-2 333 4.11 0 10 7 2 2RJ-W 2+ 1230 4.21 0 24 12 3 4RJ-W 0-5 54 4.15 0 4 0 0 0RJ-W 5+ 1130 4.03 0 20 1 1 1

Vegetated

RJ-W 0-10 33 4.94 0 69 2 1 2RJ-W 10-20 23 4.94 0 18 2 0 2RJ-W 20-30 25 5.08 0 7 1 0 0RJ-W 30-40 28 4.90 0 5 1 0 1RJ-W 40+ 403 4.52 0 24 2 1 2


APPENDIX B

Figure B 1 Temperature cross-sections measured in Whites heap

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10DECEMBER 1984

34°C

34°C 34°C38°C 38°C

42°C

42°C42°C 46°C46°C

B

A

E

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10APRIL 1990

30°C

30°C

34°C 34°C38°C 38°C

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10SEPTEMBER 1987

30°C

30°C

34°C 34°C38°C 38°C

200m 400m 600m

70m

80m

90m

100m

AHD

0m

EB

AFEBRUARY 1983

50°C

46°C

42°C

38°C


Figure B 2 Temperature cross-sections measured in Whites heap

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10JUNE 1993

30°C 34°C

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10JUNE 1996

26°C

30°C

26°C

30°C

34°C34°C

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10JUNE 1997

30°C

34°C34°C

30°C

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10JUNE 1998

30°C

30°C

30°C


Figure B 3 Temperature cross-sections measured in Intermediate heap

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

DECEMBER 1985

46°C34°C

38°C

42°C

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

SEPTEMBER 1990

34°C

30°C

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

JUNE 1987

34°C30°C

38°C

42°C60m

70m

80mAHD

0m 100m 200m 300m

Zg K Yg

QX

W R

OCTOBER 1984

34°C50°C

46°C

42°C

38°C


Figure B 4 Temperature cross-sections measured in Intermediate heap

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

JUNE 1993

34°C

30°C

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

JUNE 1996

26°C

30°C

26°C

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

JUNE 1997

30°C

26°C26°C

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

30°C

JUNE 1998


Figure B 5 Temperature cross-sections measured in Dysons heap

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10DECEMBER 1998

32°C 30°C

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10SEPTEMBER 1998

34°C

32°C

30°C

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10JUNE 1998

32°C

32°C

30°C

28°C

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10JUNE 1997

30°C

30°C28°C26°C

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10JUNE 1996

32°C

32°C

30°C

28°C

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10FEBRUARY 1996

32°C

30°C


Figure B 6 Oxygen concentration cross-sections measured in Whites heap

0m 200m 400m 500m

70m

80m

90m

100mAHD

EB

A

15

105

21

APRIL 1983

0m 200m 400m 500m

70m

80m

90m

100mAHD

EB

A

15

10521

SEPTEMBER 1983

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10FEBRUARY 1986

0.2

1

5

1015

B

A

E

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10SEPTEMBER 1986

1

5

10

15

B

A

E



100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

0.2

510

FEB RUARY 1989

1

0 .2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

0.2

510

MARCH 1988

1

0.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10AUGUS T 1989

5

10 .2

1

1 0.210

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10JUNE 1988

5

0.2

1

1 0

1

0.2



100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

1211 10

10

DECEMBER 1991

1

5

0.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10S EPTEMBER 1990

5

1 0.2

1

5 1 0.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

10

APRIL 1991

1

5

0.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

0.2

510

FEB RUARY 1990

1

0.2



100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10NOVEMBER 1994

10

5

1

1

10 5

0.2

1

5

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

10

DECEMB ER 1992

5

10.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

0.21

5

10

JUNE 1993

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10

0.2

5

10

MAY 1992

1



100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10MARCH 1995

105

1

1

0.2

1051

0.2

0.2

1

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10APRIL 1996

105

1

1

0.2

1051

0.2

0.2

1

1

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10SEPTEMBER 1995

105 11

0.2

10

51

0.2

0.2

100m

AHD

90m

80m

70m

0m 200m 400m 600m

15

1413

12

11 10OCTOBER 1996

105

10.2

10

510.2

1

1

0.2

0.2



1 00m

AHD

9 0m

8 0m

7 0m

0m 20 0m 40 0m 6 00 m

15

1 41 3

12

11 10APRIL 1997

10

5

1

10.2

10 510.2

0.21

0.2

0.2

1 00m

AHD

9 0m

8 0m

7 0m

0m 20 0m 40 0m 6 00 m

15

1 41 3

12

11 10APRIL 1998

10

5

1

10.2

10 51

0.2

0.2

1 00 m

AHD

9 0m

8 0m

7 0m

0m 2 00m 40 0m 600 m

15

141 3

12

11 10OCTOBER 1997

1010

5

5

1

0.2

1

5

1

0.2

1 00 m

AHD

9 0m

8 0m

7 0m

0m 2 00m 40 0m 600 m

15

141 3

12

11 10OCTOBER 1998

105

10

1

5

1

1

0.2

0.2


Figure B 12 Oxygen concentration cross-sections measured in Intermediate heap

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

FEBRUARY 1986

1051

0.2105

0m 100m 200m 300m

60m

70m

80mAHD

Zg K Yg

QX

W R1

10

15

55

15

10

1

APRIL 1984

10

0m 100m 200m 300m

60m

70m

80mAHD

Zg K Yg

QX

W R

1

10

16

4

41

2

101

OCTOBER 1984

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

MARCH 1988

1051

0.210

5

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

SEPTEMBER 1986

1051

0.2105

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6105

JUNE 1988

10.2

510.2



0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

APRIL 1991

101

0.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

FEBRUARY 1990

1051

0.2

10510.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6101

DECEMBER 1991

101

0.20.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6105

SEPTEMBER 1990

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6105

AUGUST 1989

10.2 51

0.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

FEBRUARY 1989

1051 0.2

10510.2



10 51

0.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

NOVEMBER 1994

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6101

DECEMBER 1992

101

0.20.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

0.2

JUNE 1993

101

0.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

MAY 1992

101

0.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

SEPTEMBER 1995

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

MARCH 1995

105

10.2



0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

1

10 51

0.2

APRIL 1998

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

APRIL 1997

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

APRIL 1996

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

1

10 51

0.2

OCTOBER 1998

1 105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

OCTOBER 1997

105

10.2

0m 100m 200m 300m

60m

70m

80mAHD 19

16141152 6

10 51

0.2

SEPTEMBER 1996

105

10.2


Figure B 16 Oxygen concentration cross-sections in Dysons heap

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10OCTOBER 1998

5

1

15

10

10 15

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10SEPTEMBER 1997

15

51

15

10

10

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10SEPTEMBER 1996

15105

1 15

10

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10MARCH 1998

15

5

1

15

10

10

105 5

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10APRIL 1997

1510

51

15

105

10

0m 100m 200m 300m

70m

80m

90m

100mAHD

6 7 8 39 10FEBRUARY 1996

1510

1051 15

10

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RUM JUNGLE REHABILITATION PROJECT MONITORING REPORT 1993 … · rum jungle rehabilitation project monitoring report 1993-1998 edited by s m pidsley technical report number 01/2002