EIS 305

Salinity in the Hunter River: a report on the generation,

treatment and disposal of saline minewater SALINITY IN THE HUNTER RIVER

A REPORT ON THE GENERATION, TREATMENTAND DISPOSAL OF SALINE MINEWATER NEW SOUTH WALES COAL ASSOCIATION

SALINITY IN THE HUNTER RIVER

I. r A REPORT ON THE GENERATION, TREATMENT AND DISPOSAL OF SALINE MINEWATER

I

PREPARED FOR: PREPARED BY:

NEW SOUTH WALES COAL ASSOCIATION CROFT & ASSOCIATES PTY. LIMITED • EAGLE HOUSE 125 BULLSTREET 25 WATT STREET P.O. BOX 5131B NEWCASTLE 2300 NEWCASTLE WEST 2302 049 26118 049261828 NATIONAL MUTUAL CENTRE LEVEL 2 IL 44 MARKET STREET SYDNEY 2000 02 297 202 DECEMBER 1983

91 if tiwtsiiiui'ti 1

TABLE OF CONTENTS

Page SECTION 1: INTRODUCTION 1.1 STUDY BACKGROUND 1 1.2 STUDY OBJECTIVES 2 1.3 COMPANION STUDIES 3 1.4 ACKNOWLEDGEMENTS 3

SECTION 2: THE HUNTER REGION 2.1 GEOGRAPHY 4 2.2 GEOLOGY AND SOILS 4 2.3 METEOROLOGY 5 . 2.4 LAND USE 7 2.5 SURFACE WATERS 7 2.6 GROUNDWATER 8 SECTION 3: PROPOSED DEVELOPMENTS 3.1 REGIONAL DEVELOPMENT 9 3.2 COAL DEVELOPMENT 9 3.3 POWER GENERATION 11 3.4 COAL LIQUEFACTION 11 3.5 URBAN GROWTH 11 O 3.6 AGRICULTURE 12 3.7 FUTURE WATER REQUIREMENTS 12

SECTION 4 ORIGINS OF SALINITY

4.1 HISTORY OF SALINITY 14 4.2 HYDROLOGIC PROCESSES 14 4.3 TYPES OF LAND SALINISATION 15 4.4 DRY LAND SALINISATION 16 4.5 IRRIGATION SALINITY 16

SECTION 5 SALINITY MODEL FOR THE HUNTER RIVER

5.1 MODEL SPECIFICATION 18 5.2 DATA SOURCES 18 5.3 WATER RESOURCES COMMISSION MODEL 19 5.4 LOGIC NETWORK 19 5.5 METHODOLOGY 21 5.6 MODEL OUTPUT 24

SECTION 6: COLLIERY WATER BALANCES . L

fl

6.1 THE CONCEPT OF WATER BALANCE 30 6.2 COLLIERY PROPRIETORS QUESTIONNAIRE 30 6.3 WATER MANAGEMENT STRATEGIES 31 6.4 WATER SUPPLY AND CONSUMPTION 31 6.5 COMPUTER SIMULATIONS 33 6.6 MODEL APPLICATION 35 6.7 WATER BALANCES FOR INDIVIDUAL MINES 36

SECTION 7 : CONSEQUENCES OF EXPANSION IN COAL MINING

7.1 INCREASES IN WATER DEMANDS 38 7.2 DISCHARGE REQUIREMENTS 38 7.3 CUMULATIVE IMPACTS OF MINEWATER DISCHARGES 39

SECTION 8 TREATMENT AND DISPOSAL OF SALINE WATER

8.1 OVERVIEW 42 8.2 DISPOSAL ALTERNATIVES 42 8.3 STAGED DISCHARGE 42 8.4 TRANSPORT BY PIPELINE TO SUITABLE RECEIVING WATERS 43 8.5 DEEP WELL INJECTIONS 44 8.6 EVAPORATION AND IN-PIT BURIAL 45 0 8.7 DESCRIPTION OF DESALINATION PROCESSES 46 8.7.1 Membrane Processes 46 8.7.2 Phase Change Processes by Distillation 49 8.7.3 Phase Change Processes by Freezing 52 8.7.4 Relative Economics of Desalination Processes 53

SECTION 9 : TOLERANCE OF IRRIGATED CROPS TO SALINITY

9.1 WATER FOR IRRIGATION 58 9.2 SALINITY EFFECTS ON CROP YIELDS 58 9.3 IRRIGATED CROPS GROWN ALONG THE HUNTER RIVER 59 0 9.4 SALINITY TOLERANCE OF CROPS 60 9.5 CHLORIDE TOXICITY 64 9.6 SODIUM HAZARD 66 9.7 ECONOMIC VALUE OF AGRICULTURAL OUTPUT 67 9.8 CONCLUSIONS 70

SECTION 10 : FINDINGS AND CONCLUSIONS 72

REFERENCES 75 0

APPENDIX 1 : N.S.W. COAL ASSOCIATION QUESTIONNAIRE OF COLLIERIES IN THE UPPER HUNTER REGION - SURVEY SHEET AND INSTRUCTIONS 78

0 APPENDIX 2 : SAMPLE OUTPUT FROM SALINITY MODEL 79

APPENDIX 3 : DETAILS OF TYPICAL MINES ADOPTED FOR WATER BALANCE MODELLING 92

APPENDIX 4 : SAMPLE OUTPUT FROM MINEWATER BALANCE MODEL 93

APPENDIX 5 SALINITY VALUES IN THE HUNTER RIVER WITH DIFFERENT LEVELS OF MINE DISCHARGES

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im NTRODUCTON

SECTION 1 1

1. INTRODUCTION

1.1 STUDY BACKGROUND

The Hunter Valley has had a long history as an important centre of primary and secondary industry in New South Wales. The Upper Hunter provides a significant proportion of the State's milk and beef requirements, and since the beginning of the Nineteenth Century, has supplied coal for both domestic and overseas markets. In recent times, much of the State's capital investment has been directed to the Hunter region. Major power generation facilities have been established and preliminary planning has commenced for the manufacture of liquid synthetic fuels. Substantial water resource projects are being undertaken or are being planned with the construction of the Glennies Creek Dam, the Barnard River scheme and the enlargement of Glenbawn Darn.

The coal industry is at the heart of current investment plans. Vast reserves of good quality steaming and coking coals are available in the valley, much of it at comparatively shallow depths. With the economies of scale introduced by modern earthmoving equipment, thirteen opencut mines are now producing coal. In the coming decade, expansion of these mines together with the establishment of a number of proposed new collieries will have the potential to substantially increase regional coal output.

The Valley is comparatively well settled, with established communities and physical infrastructure. A wide diversity of land uses make various calls on the region's natural resources. The Hunter River and its major tributaries supply most of the water needed for agricultural and other purposes. The equitable allocation of water to different geographic areas and amongst various user groups requires the application of a rational and wide reaching resource management strategy. Substantial demands are already being placed on water from the river, and these demands will increase with expansions in irrigation, mining and power generation.

In addition to volumetric requirements, the maintenance of satisfactory water quality will become an increasingly important objective. Runoff from some parts of the river catchment is moderately to highly saline under natural conditions, particularly during low flow regimes. There can be quantifiable costs, both economic and environmental, in permitting river salinity to increase. Whilst there is a well developed legislative 0 framework for the protection of water quality in rivers, the setting of appropriate and achievable control standards is a pre-requisite for successful environmental protection.

To encourage research and informed discussion on aspects of consumption and water quality in the Hunter, the New South Wales Coal Association commissioned Croft & Associates Pty. Limited to undertake a study of river salinity. The present report details the approaches, findings and conclusions of the study team. •

0

1.2 STUDY OBJECTIVES

The objectives of the salinity study were as follows:

* to investigate the causes and effects of salinity in the Hunter River

* to quantify under what circumstances coal mines may need to discharge saline waters

* to determine by superimposing the findings of the above enquiries, what effects an expansion of mining could have on the Hunter River

* to establish what measures are feasible to reduce these impacts

The study team responded to a steering group consisting of the Environmental Committee of the New South Wales Coal Association. Interim findings and study directions were discussed at progress meetings, and beneficial feed-back was obtained from colliery operators with mines throughout the study area.

The present report commences with a brief account of the general characteristics of the Hunter Region, and outlines some of the developments proposed in the coming 10 to 20 years. It then describes the origins of land and river salinisation. Details of a computer based mathematical model are presented to quantify river flows and salt loads under a variety of meteorological conditions. Further models are then described to evaluate water balances in operating mines. The outputs of these models are combined to investigate short and long term impacts from existing and proposed collieries. Options for the treatment and disposal of excess saline waters are reviewed, and the tolerance of irrigated crops to varying salinity levels is explored. A final section presents the findings and conclusions of the study. Background information, detailed technical matters and descriptions of the various computer simulations are included as appendices.

1.3 COMPANION STUDIES

The present salinity study is one of a number of initiatives supported by the New South Wales Coal Association. Companion studies have been commissioned into several research areas associated with the mining and beneficiation of coal. Two other projects are of particular relevance. The first, being conducted by Australian Groundwater Consultants Pty. Ltd. is examining the quality and availability of groundwater throughout the Hunter Valley. A second project being undertaken by the N.S.W. Soil Conservation Service is researching rehabilitation techniques in opencut coal mines. 3

1.4 ACKNOWLEDGEMENTS

The study team would like to formally acknowledge the support, assistance and guidance provided by the Environmental Committee of the New South Wales Coal Association under the chairmanship of Mr. B. Howe. Committee members were drawn from most of the operating mines in the Upper Hunter, and they were able to provide a wealth of detailed information on aspects of colliery planning, water conservation and pollution control.

The permanent staff of the Association were able to provide a valuable overview of issues relevant to all producers. Special thanks must be given to Mr. J. Hannan, Executive Officer, Technical and Mr. K.C. Wallin, Secretary, N.S.W. Environmental Committee for their encouragement and co- ordination. Finally, we would like to acknowledge the help of the Water Resources Commission in providing river gauging and monitoring data and in discussions held at the beginning of our research programme.

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.

0 THE HUNTER REGION

SECTION 2

4

2. THE HUNTER REGION

2.1 GEOGRAPHY

The Hunter Valley is a drainage basin on the central coast of New South Wales. It is located about 140 kilometres north of Sydney, and occupies a total area of about 22,000 square kilometres. Of the total area, about 16,449 square kilometres are upstream of the township of Singleton. A locality plan is given in Figure 1.

The Valley is bounded by rugged hills with deeply dissected gullies. The Nt. Royal Range and the plateau of Barrington Tops form the northeast boundary of the catchment. Directly north, the watershed lies in the Liverpool Range. The Valley is surrounded on the northwest and west by the Great Dividing Range. The most westerly point is some 250 kilometres from the coast. The southern catchnient boundary is on a sandstone plateau which 0 is part of the Triassic Sandstones of the Sydney Basin.

The watershed of the Valley rises to a maximum elevation of about 1580 metres. Over 40 per cent of the Upper Hunter is mountainous or rugged, with land slopes in excess of 15 degrees. Approximately equal proportions of the remainder are hilly, undulating and flat, as shown in Table 1. [IJ TABLE 1 LAND SLOPE CATEGORIES

Slope Percentage of Land Area 0 (Degrees)

>15 42 8-15 18 3-8 20 C <3 20

100

Source: Ref. 29

2.2 GEOLOGY AND SOILS

The geology of the Hunter is the single most significant determinant of water quality both in surface runoff and groundwater. A number of geologically distinct areas can be identified, each causing different chemical characteristics in runoff waters. The various geological 0 sequences are given on Figure 1 as follows: 5

* CARBONIFEROUS

The major areas of Carboniferous age are the northeast of the basin in the Mt. Royal Range. These sequences are associated with the New England Geosyncline. They are resistant to weathering and form rugged topography. Soils are generally poorly developed.

* PERMIAN

Perrnian sediments occupy the central part of the Valley and underly more recent sediments to the south. They form part of the Sydney Basin, and they contain substantial coal reserves. Coal seams alternate with a conformable series of marine sandstones, siltstones and mudstones. These strata outcrop in a belt up to 30 km wide in the central part of the Valley, and in some areas have been intruded and indurated by numerous dykes and sills (ref. 1). Permian sediments are highly significant from a water quality viewpoint, in that they contain connate salts. These salts render groundwater highly to very highly saline and when leached into receiving watercourses, lower the quality of creeks and rivers.

* TRIASSIC

The southern sections of the drainage basin are composed of triassic shales, claystones, sandstones and conglomerates of the Narrabeen Group. Except for occasional alluvial flats, these areas are overlain by poor sandy soils.

* TERTIARY

The basalts in the northwest of the Valley are of Tertiary age. They form part of the Great Artesian Basin. Surface profiles are rugged, with well developed soils.

* TERTIARY-RECENT

Clay, sand and gravel alluvium form the floodplain of the Hunter and its tributaries. The fertile floodplain supports much of the agricultural enterprise in the Valley. It ranges from about 3 km in the upper reaches to approximately 4 km wide at Singleton. Soils are generally free draining, making them suitable for irrigation.

2.3 METEOROLOGY

Compared to much of New South Wales, the Hunter Basin is relatively well watered (ref. 30). Average annual rainfall varies from 1150 mm in the lower coastal areas to 560 mm in the higher western fringes. Rainfall is unequally distributed throughout the year. Most falls occur in summer, UIL V V V V V V V V V LEGEND V V V V V V V V V V V V V V V V V V V V V V V V V V V V ' v v/v',bl V Tertiary - Recent Alluvium-clay, sand & gravel V V V V V V V V V V V V ' V V V V v 'v V v ,4. v vtV V V V V V V Jurassic Sandstone and shale V v ' v v V v%v v v v v 0 y V v v v ' V v v/v v v V V Hawkesbury V V V V V V V V V V V V V7V v V Quartz-sandstone Sandstone E1 v v v V v v v v v VV v V V V V V Triassic V V V V V V V V V V Narrabeen Shale, claystone, sandstone v v v v v v ¼ I" V V V V V V •\V V V VVI V V V V V Group & conglomerates V V V V V V v v v v v V v 'v v v v Upper Coal Sandstone, shale, conglomerates V VJV V V V V V V Measures & coal ...... v v v v v v V V - 'V V V V . ...... v v V Upper Marine Sandstone, shale & / vr- Series conglomerates an Lower Coal Sandstone, shale, conglomerates Measures & coal Lower Marine Sandstone, mudstone & tuff Series erous Limestone, tuff, shale & conglomerate

ion Tuff, shale, conglomerate, chert & quartzite

GraniteBasalt

PORT STEPHENS

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ç)IC "CASTLE

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LAKE WACQUARIE 0 10 20 30 40km ,ji

LOCALITY PLAN FIGURE 1 Source: N.S.W Water Resourses Commission — Wafer Resourses of the Hunter Valley 1.1

with the period December to April being relatively wet. June to September is normally moderately dry (ref. 29).

A network of rainfall gauges are maintained throughout the Valley. Typical records for two stations, Jerrys Plains and Singleton, are given in Table 2.

TABLE 2

MEAN MONTHLY RAINFALL AND RAINDAYS

J F N A N J J A S 0 N DYEAR

JERRYS PLAINS (1884 - 1978) Mean Rain- 40 fall (mm) 79 69 59 45 39 49 45 37 40 51 56 67 636 Mean Rain- days(No.) 8 7 7 6 6 7 7 7 6 7 7 7 82

SINGLETON (1881 - 1969) [J Mean Rain- fall (mm) 75 72 71 56 46 57 51 42 45 51 58 74 698 Mean Rain- days(No.) 7 7 7 7 6 7 7 7 6 7 7 7 82

• Source: Bureau of Meteorology.

Potential evaporation at Scone is given in Table 3.

TABLE 3

POTENTIAL EVAPORATION (mm)

• J F M A N J J A 5 0 N D TOTAL SCONE (1972 - 1983) 220 174 146 105 71 48 59 84 114 146 186 235 15 • Source: Bureau of Meteorology

L 7

2.4 LAND USE

Small quantities of outcrop coal were obtained from what was to become Newcastle in the 1790's, but permanent European settlement did not commence at the mouth of the Hunter River until 1801. The Singleton/Patrick Plains area was discovered by John Howe in 1819 and 1820. By 1823, free settlers began to arrive and spread quickly through the Valley. Early towns such as Maitland and Raymond Terrace developed as river ports. Other towns such as Singleton and Muswellbrook were strategically placed on land transport rou-tes and expanded as rural service centres. Maitland was the largest urban area till the 1890's when coal mining allowed Newcastle to gain the ascendancy (ref. 22). In 1976, 87 per cent of the regional population lived in the Lower Hunter.

Agriculture is the predominant land use in the Upper Hunter, and it is an important sector of the regional economy (ref. 21). With a range of soil types and climate, the region is a very diversified rural producer. Milk, beef cattle, poultry and eggs contribute almost 70 per cent of the value of agricultural output (ref. 20). Milk and cattle are the two largest sources of farm income in the Upper Hunter. In 1981-82, the market value of total agricultural output based on Australian Bureau of Statistics estimates was $63 Million.

The Newcastle and Tomago Coal Measures were mined throughout the Nineteenth Century, but the commencement of mining in the Greta Coal Seam in 1886 led to a rapid expansion in Lower Hunter coal towns. By the start of the present century, the black coal industry was well established, due to the strategic location of the coalfields near population centres and coastal shipping facilities. By the late 1970's growth in overseas thermal coal markets and the development of major opencut mines have led to rapid expansion of the industry. In 1982, the Joint Coal Board gave the estimated value of annual coal produced as about $800 Million.

2.5 SURFACE WATERS

The Hunter River and its tributaries provide the main sources of water in the Valley. Average annual runoff is about 11 per cent of annual rainfall, though this varies with the particular part of the catchment (ref. 29). For the present report, it is useful to divide the study area into three sections.

* The Goulburn River with a catchment of 7,822 km 2 * The Hunter River upstream of the Goulburn, with an area of 4,584 km 2 * The balance between their confluence and Glendon Brook.

Whilst the Goulburn River constitutes some 45 per cent of the catchment area of the Upper Hunter, it has a relatively low annual hydrological yield. River flows are about 5 per cent of total rainfall which means that the Goulburn, despite its large size, contributes only about 23 per cent to the area's long term runoff (ref. 29).

0 Streamfiows in the Valley are subject to a high degree of variability. This is most marked in the Goulburn River, where annual flows range from 1000 per cent to 3 per cent of long term averages. Monthly flows are even more variable and, as in the majority of streams in New South Wales, there is extreme variability between maximum and minimum instantaneous discharges. The highest recorded flood at Singleton occurred in February 1955 where the peak discharge was estimated to have been 12,500 cubic metres per second, or 1,080,000 ML/d.

There have been 597 days with zero flow at Singleton since 1891 (ref. 29). Greater river regulation from Glenbawn and Glennies Creek Dams will reduce the frequency of extreme low flow conditions in the Hunter.

2.6 GROUNDWATER

Groundwater is used extensively throughout the Upper Hunter. It is not uniformly distributed, and available yields and water qualities vary widely. There are two major sources of groundwater:-

* unconsolidated sediments * porous and fractured rocks.

Unconsolidated sediments mainly consist of alluvial silts, clays, sands and gravels associated with watercourses. They afford practically the only significant source of large volumes of good quality groundwater in the Upper Hunter (ref. 30). Yields from bores and wells range from 12 to 38 L/sec north of Muswellbrook, reducing to 2 to 10 L/sec between Muswellbrook and Denman. Between Denman and Singleton, average yields increase to between 10 and 25 L/sec (ref. 1). However, these better quality resources are already heavily committed. The Water Resources Commission has indicated that of the 63,000 ML/y potential yield from alluvium, some 58,000 ML/y are presently being drawn (ref. 28).

Groundwater from porous and fractured rocks occurs mainly in secondary induced structures such as fractures, joints and cleats. Whilst these strata contain considerable quantities of water, the yield from wells is poor. For example in Permian rocks, yields normally range between 0.5 and 2 L/sec at depths of 25 to 150 m. Carboniferous rocks usually range between 0.1 and 0.4 L/sec. Water from non-alluvial sources is usually too saline to be of use for anything other than stock watering. Groundwater from Perniian strata normally ranges from 1000 to 9000 mg/L TDS (Total Dissolved Solids), though readings up to 17,960 mg/L have been recorded (ref. 1).

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40 PROPCO DEVELOPMENTS

3. PROPOSED DEVELOPMENTS

3.1 REGIONAL DEVELOPMENT

In the so called 'resources boom' of 1981 and early 1982, the Hunter Region figured prominently in predictions of capital investment within New South Wales. The Department of Industrial Development and Decentralisation in danuary 1981, estimated that about 58 per cent of total investment in projects larger than $5 million was being directed to the Hunter (ref. 7). The Centre for Resource and Environmental Studies (ref. 13) estimated that about $9,537 million would be invested in the region in coal mining, coal based manufacturing and infrastructure. This estimate combined projects recently completed, those currently under construction and those foreshadowed until 1990. In February 1983, the Hunter Valley Research Foundation indicated that approximately $5,360 million dollars were being invested in projects under constuction, and a further $4,407 million dollars were being proposed for future capital investment (ref. 12). The Foundation's figures included both commercial investments and projects valued at less than $5 million dollars. It is significant that about 74 per cent of expenditure for future projects was categorised under coal mining.

The present downturn in general economic activity in Australia and in particular the depressed demand for coal by overseas customers has led to a re-evaluation of many coal mining projects. Development timetables are being extended and more marginal deposits are being indefinitely deferred. It is therefore possible that some of the predictions given in the present report will be found to be too optimistic. However, the long term demand for the region's energy reserves is assured, and there is general agreement that extraction of these resources will ultimately occur. The exact timetable will depend on market forces, extraction costs and alternative sources of supply.

Coal development will be associated with growth in a number of other sectors including power generation and possibly the synthesis of liquid fuels. The scope of these developments is briefly outlined in the remainder of this section.

3.2 COAL DEVELOPMENT

The expansion of the coal industry in the Upper Hunter will be the driving force for many other regional developments. To quantify this expansion for the present study, a questionnaire was sent to all members of the N.S.W. Coal Association with interests in the Upper Hunter. Details of the questionnaire are given in Section 6, and a copy of the survey sheets are shown in Appendix 1. Members were asked to estimate the annual run-of-mine (RUM) production from their facilities over a ten year period commencing in 1985. The results of the survey are presented in Table 4. It was estimated that by 1994, approximately 29 collieries will be producing some 93 Mt of RUM coal per annum. This can be compared with Joint Coal Board statistics for 1981 where the Singleton-North West District produced 18.4 10

TABLE 4

ESTIMATED MAXIMUM ANNUAL RUN-OF-MINE PRODUCTION (Mt) Ll me 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

Mt. Sugarloaf* 0.65< >0.65 Wambo* 1.2< >1.2 BBC* 43< >43 Pikes Gully* 0.4< >0.4 Foybrook* 0.5< >0.5 Foybrook North* 1.0 1.0 0.96< >0.96 Glendell+ 3.6< >3.6 Ravensworth No.2 S Colliery+ 3.4 4.0 4.0 4.2 4.2 3.5 3.5 3.5 3.5 3.5 Swamp Creek* 1.9<- >1.9 United+ 2.7< >2.7 Mt.Arthur South* 0.42 2.93 4.65 5.9 6.0 6.0 6.0 6.0 6.0 6.2 Mt.Arthur North+ 5.4 8.0 10.0 10.5 11.0< >11.0 Howick* 2.74 3.95 4.99 5.95 5.95 5.95 5.95 5.95 5.95 5.95 S H.V.No.1 ) H.V.No.2 ) 5.0 5.0 5.0 5.0 5.0 5.5 6.0 6.0 5.7 5.0 Rixs Creek 0.8 1.4< >1.4 Bulga+ - - - 1.0 2.0 2.7< >2.7 Mt. Thorley+ 4.3< >4.3 Saxonvale* 4.88 6.03 7.0< ->7.0 [] Warkworth* 3.5 3.6 3.9 3.9 4.3< >4.3 Drayton+ 3.5 Liddell* 0.5 Dartbrook+ 2.0 4.0 7.0< >7.0 Liddell State* 0.6 Muswellbrook+ 1.0< >3.0 S :BaysWater* 1.6 1.6 1.6 1.6 2.0< 2.0 Great Greta+ 0.5< ->0.5 Mitchells Flat+ 2.0< >2.0 Ulan+ 6.2< >6.2 S Total ROM Production 92.86

Key: * Questionnaire + EIS or other published document S

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0

11

Mt of RUM coal (ref. 14). This latter figure would require slight modification to be strictly comparable, in that the statistics include both Gunnedah No. 2 and Preston Extended Collieries, but exclude IJlan. However in broad terms, a four to five-fold increase in coal output is being projected. The survey was conducted during a period of more buoyant market conditions, so projected targets would now appear optimistic. However, the higher figures have been retained in the present study to give an appreciation of a full scale expansion in the industry. The locations of existing and proposed mines are given in Figure 2.

3.3 POWER GENERATION

The Electricity Commission of N.S.W. is undertaking a major expansion of the State's electricity generating capacity. Much of that expansion is occurring in the Hunter Region. Projects include completion of the 2640 megawatt Eraring Power Station, and the construction of four 660 MW units at Bayswater Power Station. Eraring is expected to be completed in 1984 and Bayswater about 1988. In addition, modification or upgrading works are programmed for Liddell, Vales Point and Munmorah Stations.

Once again, the cancellation or postponement of major industrial projects has led to a reduction in demand for electrical energy. In particular, the cancellation of the Lochinvar Aluminium Smelter and the deferral of the third potline at Alcan's Kurri Kurri Smelter have substantially reduced projected base load requirements. However, much of the construction is already committed, and it is possible that reduced demand will be accommodated by delays to the proposed Mount Piper Power Station in the Central West of the State.

3.4 COAL LIQUEFACTION

Toward the end of the century, shortages in liquid hydrocarbon fuels could make a coal liquefaction plant a viable proposition. A large coal resource to the west of Muswellbrook known as Authorisation 102 is currently held by the Department of Mineral Resources. The area has been put forward as being suitable for coal conversion, and expressions of interest have been called to develop a suitable plant. Declines in the world price of crude oil have adversely affected the economics of coal conversion, and it appears that a commercial scale operation could not be established before the late 1990's. Over the timetable of the present report, it has been assumed that no provision need be made for coal liquefaction.

3.5 URBAN GROWTH

Studies conducted by the Department of Environment & Planning point to a steady increase in population at Singleton and urban centres to the north and west. The Department's population projections over five year intervals to the Year 2001 are given in Table 5. Over a twenty year period, a total growth of 54.2 per cent is predicted. 12

TABLE 5

POPULATION PROJECTIONS FOR LOCAL GOVERNMENT AREAS IN THE UPPER HUNTER, 1981-2001 (with construction workforce)

L.G.A. 1981 1986 1991 1996 2001 % Change 1981- 2001

Merriwa 2450 2520 2580 2310 2040 -16.7 Murrurundi 2300 2380 2440 2250 2060 -10.4 Muswellbrook 13200 23140 19970 20940 22010 +66.7 Scone 8600 10130 10420 10680 10970 +27.6 Singleton 15300 24920 25080 26200 27440 +79.4

Total 41850 63090 60490 62380 64520 +54.2

Source: DEP, 1982.

3.6 AGRICULTURE

Growth in irrigation landholdings will depend on the availability of water and markets for agricultural products. The Water Resources Commission has S indicated that the potential for extending the area of irrigation will depend on whether a storage dam is constructed on the Goulburn River catchment (ref. 28). The decision to establish the Goulburn River National Park has led to an abandonment of the proposed Kerrabee Dam, and no further consideration is being given to the Lees Pinch Dam some 70 km further upstream. With no dams being proposed for the Goulburn River, expansion in irrigation output will be confined to a more intensive utilisation of allocations, together with a modest increase in authorised areas on the Glennies Creek catchment.

3.7 FUTURE WATER REQUIREMENTS C

One of the major concerns of existing residents in the Upper Hunter is the effects of industrial development on the quantity and quality of water available from the river. With greater river regulation and the granting of priority drawing rights to urban and industrial users, the proportion of residual water available for irrigation may decline. As discussed by de Kantzow (ref. 6), water for irrigation becomes critical during drought years if all other users are given guarantees of supply.

In the Water Resources Commission's 1982 review of future water requirements in the Hunter (ref. 28), two sets of demand projections are S

11 LEND

A 13 CoI & Al lied OperdtiorlS P/Ltd L/ Bridge & Oil Limited A 17 Barix Pty. Ltd A 44 Maitland Main Coils. Pty Ltd. 2 Aberdare North A 72 Clutha Development Pty. Ltd. 9 Angus Place A 81 Eric Newharn (Wallerawang) Pty. Ltd 11 Bayswater No2 A 89 Bloomfield Colleries Pty Ltd 12 Beibird A 90 Consolidated Gold Fields Aust.Ltd. 120 Buchanan Lemington A102 Dept of Mineral Resources 36 Foybrook A128 Golliri Walisend Coal Co., Ltd. 37 Great Greta A129 Carpentaria Exploration Co., Pty Ltd. 44 Howick Open Cut A168 Electricity Commission of N.S.W. 45 Nardell A169 Electricity Commission of N.S.W. 46 Hunter Valley No:1 AiR Bayswater Colliery Co. Pty Ltd. 56 Liddell A172 Bayswater Colliery Co. Pty Ltd. 57 Liddell S.C.M A173 Thiess Bros. Pty. Ltd. 61 Mailtand Main A174 Mt. Sugarloaf Collieries Pty Ltd. 63 Millfield A176 Muswellbrook Coal Co., Pty Ltd. 64 Mi Ilfield North A205 Dept. of Mineral Resources 66 Mount Thorley A212 Barix Pty. Ltd. 70 Muswellbrook A219 The Newcastle Wailsend Coal Co., 76 Newdell A229 Dept of Mineral Resources 83 Pelton A238 Electricity Conveission of N.S.W. 85 Ravensworth No:2 A239 Aust. Coal & Shale Employees Fed. 91 Stanford Main No:2 A256 The Bel iambi Coal Conipany Ltd. 94 Swamp Creek A262 Buchanan Borehole Collieries Pty. Ltd. 106 Wambo A263 Dept of Mineral Resources 116 Durham North A?86 Dept of Mineral Resources 118 Warkworth A290 The Nardell Colliery Pty. Ltd. 119 Drayton A300 Coal & Allied Operations Pty. Ltd. 120 Saxonvale A308 Southland Coal Pty. Ltd. 121 Hunter Valley Extended

CD4 Coal Development Area C13 Carpentaria Exploration Co. Pty Ltd CD5 Coal Development Area

AL N Scale 0 5 10 20km

MINING PROPOSALS WITHIN Department of Mineral Resources THE STUDY AREA FIGURE 2 13

given. The first assumes that high growth will occur in all sectors. Water will be provided to the Hunter District Water Board for urban purposes, a coal liquefaction plant will be established by 1995 and irrigation demands will increase by about 67 per cent. The second set of forecasts assumes a low growth situation with reduced demand by urban and irrigation users, and an indefinite deferral of any coal liquefaction facilities. Total demands for the high and low growth areas are given in Table 6 for the Year 2005. For purposes of comparison, current water consumption is also shown.

TABLE 6 • CURRENT AND PREDICTED WATER DEMANDS (ML/year)

Type of Use Current Water High Growth Low Growth Demand Option Option Year 2005 Year 2005

Riparian and losses 50 000 50 000 50 000 Maintenance of minimum flow at Maitland 19 000 19 000 19 000 Urban 5 000 44 000 18 000 Power generation 25 000 100 000 100 000 Coal liquefaction - 45 000 - Coal mining and washing 5 000 26 000 21 000 Irrigation 74 000 124 000 90 000

Total 178 000 408 000 298 000 Say 410 000 300 000

The Commission notes that although the Hunter Basin stores about 30 million megalitres of groundwater, most is too saline for irrigation and of the remainder, only a limited proportion can be extracted. The potential yields from alluvial aquifers and the Tomago Sandbeds are almost fully committed, so that groundwater is not a potential source of supply for the main growth in water requirements. In other words almost all growth in supply capacity will come from greater regulation of surface water flows. a Ll OFUGUS OF SALMTY

r L

14

4. ORIGINS OF SALINITY

4.1 HISTORY OF SALINITY

The ancient civilisations of the Fertile Crescent were the first large scale communities supported by irrigation agriculture. These early civilisations were located in the valley between the Tigris and Euphrates Rivers in modern day Iraq. Settlement then spread through what is now Iran, Afghanistan, Pakistan and India to the river valleys of China. Irrigation allowed farmers to grow more crops per year. It made farms less susceptible to droughts and permitted the cultivation of more marginal lands. However, most of these earlier schemes were subsequently abandoned because of the buildup of salt in the soil . It has been speculated for example that the fall of the Mesopotamian civilisation in the thirteenth century BC was "....due as much to the salinisation of soils and the silting of delivery channels in its irrigation areas as to the ravages of Mongolian invaders" (ref. 13).

One exception to this general trend was the Nile Valley. It is probable that the annual floods in the Nile flushed away accumulated salt and maintained a salinity balance. With the construction of the Aswan Dam, flooding has been reduced and salinity is now becoming a problem for irrigators along the Nile (ref. 24).

Although intensive agriculture has a far more recent history in Australia, salinity problems have already become evident. Extensive land clearing in Western Australia has led to raised water tables and increased salinity in surface runoff. Large areas in the catchment of the Collie River have been cleared for farming, and this has resulted in a build up of salinity in the Wellington Dam. Perhaps the most widely known example of catchment basin salinisation is given by the Murray River. The Murray drains an area of 1.06 million square kilometres in three states. This represents about one seventh of the area of Australia. The river irrigates some 6700 square kilometres of land as well as providing domestic and industrial supplies for towns in New South Wales and Victoria. In some years up to eighty per cent of South Australia's domestic and industrial supplies are drawn from the Murray (ref. 17). The River Murray Commission was established in 1915, but due to a limited charter has not proved effective in controlling salinity problems. By 1977, urgent Commonwealth/State initiatives were seen as being required to deal with increasingly serious salinity and drainage issues. These mainly relate to high water tables and land salinisation in the Riverine Plains, and high river salinities in the Mallee zone.

4.2 HYDROLOGIC PROCESSES

Precipitation, percolation, runoff and evaporation are stages in the hydrologic cycle. Water evaporates from the world's oceans and is transported by moving air masses. Under certain conditions the water vapour first condenses into clouds and then falls as precipitation. Rain which falls onto land can follow several paths. Most is briefly retained 15

in the soil and re-evaporated or transpired by plants. A proportion flows overland to streams, and the remainder infiltrates into the earth to become terrestrial groundwater. Under gravity both groundwater and surface flows move to lower elevations and are ultimately discharged into the sea to recommence the cycle. This simplified description accounts for the major processes, though secondary losses occur through direct evaporation from streams, interception by vegetation and interfiow between surface and groundwaters.

Superimposed on the hydrologic cycle is a process of salt transport. Rocks weather at higher elevations, allowing the entry of moisture. Water dissolves mineral salts which are then transported by rivulets, creeks and streams to rivers. As rivers flow downstream, dissolved salt concentrations and salt loads build up, until finally the waterways discharge into the sea. It has been calculated that due to physical, chemical and biological weathering processes over millennia, the world's oceans now contain about 3.2 x 1018 tonnes of salt (ref. 24). There are large additional quantities buried in submerged lakes and inland sinks.

All these processes can be observed in the Hunter Valley. The upper reaches of the river are low in salinity. Glenbawn Dam for example has a mean salinity of about 220 mg/L. Salinity levels increase progressively in a downstream direction. Garman (ref. 9) noted that there can be a threefold increase in salinity between Glenbawn and Greta.

Rivers act as natural drains in transporting terrestrial salt to the sea. When these natural processes are disrupted by dams, agriculture, industrial consumers and town water supplies, imbalances can occur in salt movements. Greater river regulation by storage reservoirs can prevent natural flooding from periodically flushing salt from watercourses and soils. Interception works such as those used in the Murray River accumulate salt in evaporation basins. These may offer short to medium term benefits in reducing river salt loads, but they also have the potential for contributing to longer term salt imbalances.

4.3 TYPES OF LAND SALINISATION

There are two kinds of land salinisation. Although the consequences of each are similar, the causes are distinct and different remedial measures are called for. The first is dry land salinisation. It can be found in hollows and at the base of hills, and can be identified by bare patches of ground called salt pans. Grass will not grow and shrubs and trees lose foliage. In severe cases plant die-off occurs. Crystals of salt form on the ground surface and the soil appears wet and soggy.

The other major salt related problem is irrigation salinisation. This causes river salinities to rise, and in some circumstances can lead to elevated water table levels. Raised water tables can result in soil waterlogging and the accumulation of salts at or near the ground surface. In the absence of remedial works, the land loses its agricultural value and must be progressively abandoned. The scope of the problem can be appreciated by an FAQ and UNESCO estimate that over half of the world's irrigated land has been damaged by waterlogging or salinisation. This is S 16

leading to millions of hectares of irrigable land being made uninhabitable each year (ref. 24). Causes of land salinisation are outlined in greater detail in the remainder of this section.

4.4 DRY LAND SALINISATION I.

Geology is undoubtedly the most significant factor in regional dry land salinisation (ref. 1). Both soil type and water quality influence the formation of salt pans. However, soil types are dependent on the nature and location of parent rocks, and salinity in groundwater and surface • runoff ultimately derives from the leaching of soluble minerals from geological formations. In addition, certain land use practices can result in environmental imbalances which promote land degradation by salinisation. When land is cleared of tree cover, transpiration and interception moisture losses are reduced. Pasture grasses and crops have more shallow root structures and they draw less moisture from the soil. Water tables can • then rise, which has two consequences. Firstly, soil can become waterlogged causing plants to rot. Conditions in the root zone become anaerobic and this affects nutrient availability to plants. Well aerated conditions foster the growth of soil microflora which assist in converting nutrients and trace elements to forms that can be utilised by crops and pastures. Waterlogging suppresses these processes (ref. 17).

If groundwater is brought close enough to the ground surface, a second consequence is that direct evaporation of groundwater can take place. If the groundwater contains dissolved salts, the salts will be left behind in the soil as evaporation occurs. This can induce surface crusting and the concentration of salt in the upper salt horizons.

A first sign of dry land salinisation is the dieback of residual trees and other deep rooted plants. Grasses and other ground cover then perish and isolated salt pans form. If livestock is being run in the area, animals congregate in salt pans and lick the salt. Trampling by stock compacts upper layers of the soil and further inhibits pasture growth. The areas of • bare earth are then sensitive to soil erosion, and by concentrating surface runoff, they can contribute to erosion further downstream. If overstocking is permitted or inadequate market prices are received for agricultural produce, remedial measures to counteract soil salinity may not be economically possible. In these circumstances, salt scalding can spread progressively and tracts of land can become permanently unsuitable for • agricultural uses.

In the Hunter Valley, examples of dry land salinisation can be seen in undulating to hilly areas near Bulga and northeast of Singleton. However, it does not appear to be a major agricultural concern. I. 4.5 IRRIGATION SALINITY

Deliberate application of water to crops can cause similar salinity problems to those experienced by dry land farmers. If land without I sufficient underdrainage is irrigated, water tables rise and the ground

I. 17

becomes waterlogged. This has occurred in several places in Australia including the Kerang, Shepparton and Wakool regions. A combination of capital works and irrigation management can often be effective in ruinimising waterlogging. Well designed subsoil or tile drains can depress watertables and facilitate the return of excess waters. Conversion from overhead to drip sprinklers conserves water and minimises the build up of salt. The avoidance of midday watering is also helpful in reducing water losses and lessening leaf scalding from salt. Periodic flushing with excess water washes built up salt through the soil to horizons below the root zone.

Fortunately, the alluvium of the Hunter River is generally well leached and comparatively free draining. Excess waters are therefore able to return to the river without significantly raising regional water tables or waterlogging the ground. However, irrigation does cause evaporative losses and increases the concentration of soluble salts. Assuming there is no long term build up of salt in the soil, almost all salt abstracted from the river by irrigation drawings must be returned in a more concentrated form by groundwater. Experience in the southwest of the USA suggests that return waters are about one quarter the volume of irrigation abstractions, and are therefore four times more saline (ref. 24).

The build up of salt or application of saline irrigation water can adversely affect the structure of some soils. Soil peds can be disrupted due to the dispersive nature of clays and other fine grained components. 0 Throughout the Hunter, soils can be moderately to very highly dispersive with high sodium absorption ratios. The implications of this are described in detail in Section 9. Dispersive clays form hard impermeable crusts. The crusts interfere with the absorption of water and prevent young plant shoots from emerging. Application of saline water exacerbates these problems, particularly if salt sensitive crops are grown and poor irrigation techniques are adopted.

fl

C SAUMTY MODEL FOR THE HUNTER RFVER

In

5. SALINITY MODEL FOR THE HUNTER RIVER

5.1 MODEL SPECIFICATION

The aims of a salinity model for the Hunter River were considered to be threefold:

to understand what contributions various tributaries make to discharges and salt loads in the river

to explore how saline concentrations vary along the river under different flow conditions

to establish how salt concentrations change with greater river regulation and with point discharges and abstractions.

To achieve these objectives, a mathematical model was considered desirable to simulate what happens in various reaches of the river upstream of Glendon Brook under a range of flow conditions. It was recognised that to obtain maximum benefit from such a model, it should be capable of being updated by non-specialists when new data becomes available. It should also be 'user friendly' to encourage its utilisation as a planning tool.

5.2 DATA SOURCES 40

The Water Resources Commission maintains an extensive river gauging network throughout the Hunter Valley. The locations of major stations are given in Figure 3. Flow records in some instances extend back several decades. The oldest gauge at Singleton is understood to have been established in 1891. However, most gauges are of relatively recent origin, with many being installed in the late 1950's or 1960's. Much early flow information was collected with visual observation of staff gauges, whereas more recent records have been obtained with continuously recording float gauges or pressure gauges. However, even the accuracy of recent measurements must not be overestimated. Calibration techniques to convert flood stages to discharges are approximate, particularly under extreme flow conditions.

In addition to flow data, the Commission now records four basic parameters at each gauging station. These are pH, temperature, conductivity and turbidity. This policy was commenced in the early 1970's, so at most stations there are about ten years of results. Monthly records at a selected number of stations have been supplemented by weekly or daily readings for periods of one to two years. During 1982, the Commission installed four automatic salinity recorders at Muswellbrook, Liddell, Singleton and Greta to continuously monitor salt levels. Results from these recorders will be invaluable in the future to account for short term fluctuations in the river.

19

Despite the number of gauges distributed throughout the Hunter, there were still data gaps when attempting a detailed hydrologic model. Some tributaries were ungauged, or had only been gauged for unrepresentatively short periods. Gauges are located at potential dam sites, or where they can be easily accessed by road. To avoid recording errors due to backwater effects from the main stream, most gauges are set well back from the mouths of tributaries. Finally, conductivity data could not always be obtained for each station.

To compensate for incomplete records, a significant amount of effort was dev6ted to analysing raw data and synthesising hydrologic parameters to provide suitable input for the model. Synthetic flow duration curves were constructed for ungauged watercourses. Where possible, these were based on nearby catchments of similar areas and with similar hydrologic and meteorological characteristics. Flow differences caused by variations in catchment size were compensated by using an area correction factor. Particular difficulties were encountered in adequately quantifying the highest discharge region of each flow duration curve. The particular methodology used is described in greater detail below.

5.3 WATER RESOURCES COMMISSION MODEL

During the initial stages of the present study, discussions were held with officers of the Water Resources Commission to gain an appreciation of previous modelling undertaken in the Hunter River. The Commission developed a model to predict changes in salt concentrations in the river caused by the construction of major storage reservoirs. It is based on a relatively straight forward mass balance network. Major tributaries are identified as node points, and flows and equivalent salt loads are summed down the river. To compensate for groundwater accessions, an artificial equivalent tributary is introduced at Singleton to provide a means of adjusting for discrepancies between calculated and observed salt loads. The model was mainly intended to give a broad understanding of water quality impacts from different river management strategies. It allows for the Glenbawn and Glennies Creek Dams, and what was to have been an additional major storage at Kerrabee.

The objective of the WRC model substantially differs from what would be required for the present study. In the interests of simplicity, all minor tributaries had been deleted, and broadbrush averaging techniques used for predicting electrical conductivities. These procedures, whilst providing an overall quantification of salt loads, can lead to significant errors in certain reaches of the river. This is particularly the case in high flow conditions.

5.4 LOGIC NETWORK

The Hunter basin can rationally be defined by a series of major subcatchrnents as shown in Figure 4. The area of each is given in Table 7. ScaLe 0 5 10 20km

WMMI35IUIN 51 I-

SUBCATCHMENTS OF THE STUDY AREA FIGURE 4 TABLE 7

TRIBUTARY CATCHMENT AREAS (km2 )

Subcatchment Catchment Area Area

Pages River 1204 Glenbawn Dam 1295 Rouchel Brook 439 Dart Brook 829 Hunter River at Muswellbrook 4222 Hunter River upstream Goulburn River 4584 Goulburn River upstream Hunter River 7822 Martindale Creek 487 Saddlers Creek 96 Doyles Creek 219 Saltwater Creek 57 Bayswater Creek 142 Bowmans Creek 258 Glennies Creek 510 Wollombi Brook 1872 Loders Creek 80 Hunter River at Singleton 16449 Mudies Creek Jump Up Creek Glendon Brook

In addition to tributary inflow, about 12 per cent of the Hunter River catchment drains directly to the river.

To provide a suitable logic diagram for the river, tributaries were represented by a series of linked nodes. A nodal network had to be selected which was not excessively detailed, but which allowed adequate definition of areas that could be affected by mining. The adopted network is shown in Figure 5. It can be seen that between Denman and Singleton every major tributary has been included, whereas the Goulburn River has been represented by only two source nodes. There is only one operating mine in the Goulburn River catchment, and no others appear likely in the short to medium term. With the abandonment by the Water Resources Commission of the proposed Kerrabee Dam, there was no justification for placing additional source nodes in the Goulburn River to account for changes in catchment discharges due to greater river regulation. The Kerrabee Gauge Station 210016 provided excellent long term discharge records and a significant amount of conductivity data. It was therefore originally selected as a source node which allowed for all upstream areas in the Goulburn River catchment. Gauge records for Widden Brook, Baerami Creek and Halls Creek would then have been modelled separately and added to flows from Kerrabee. The resulting flows would have been correlated with values at Sandy Hollow, Station 210031. It was subsequently found that a 21

simple manipulation of the Kerrabee records could adequately predict Sandy Hollow readings without individually modelling the intervening tributaries. However, Wybong Creek was found to be a significant source of salt and was therefore accounted for separately.

Conversely, the model network for the Hunter River upstream of Denman at first sight appears unnecessarily detailed. There are five source nodes upstream of Muswellbrook, all of which could have been replaced by a single source node at Muswellbrook. The Muswellbrook gauge has almost eighty years of records available and is possibly one of the more reliable in the system. However, the adopted network has several significant advantages. Glenbawn Dam is entered separately, so that when the dam is enlarged, it will be a simple matter to modify the model to account for the different river regulation characteristics. Likewise, different strategies for allocating water from Glenbawn to competing water users can be directly modelled. Entering separate source nodes for Rouchel Brook and Pages River will enable future dams on these tributaries to be detailed. The former is receiving active consideration by the WRC, and a storage on the Pages River has also been proposed. Finally, separation of Dart Brook allows explicit consideration to be given to Bellambi Coal Company's Dartbrook project, and a source node for the residual subcatchment immediately upstream of Muswellbrook allows the Muswellbrook Coal Company's operations to be identified.

Consideration was originally given to inserting a check node at Denman to correlate records from Station 210055 with those at Muswellbrook. However, there are no significant intervening tributaries, and it was found that Denman values could quite accurately be predicted by applying area correction factors to Muswellbrook's discharges and salt loads. Junction nodes have been inserted below Muswellbrook to provide for direct groundwater accessions, and as a mechanism for including irrigation abstractions and losses from the river. Groundwater resources are a significant source of supply in the area, and the importance of direct recharge of alluvial aquifers from surface flow has been noted.

Between the confluence of the Hunter and Goulburn Rivers and Glendon Brook each significant tributary has been modelled. In addition to receiving inputs from each source node, further junction nodes have been provided with the ability to accept supplementary inputs and outputs. This facility allows the model to simulate direct groundwater accessions to the river, and to make due allowances for point discharges and significant water abstractions. The model can be tuned by correlating upstream discharges and salt loads with those recorded at Singleton, Station 210001. A further refinement would have been the insertion of an additional check node at Liddell, Station 210083. As only nine years records were available at this station and some data appeared anomalous, the additional check node was deleted.

5.5 METHODOLOGY

DISCHARGES

Having adopted a suitable logic network for the river and its major tributaries, the next step involved the entry of individual flows in each LOGIC NETWORK USED IN STREAM SALINITY MODEL FIGURE 5 22

watercourse. Flows are traditionally described by means of a flow duration or flow versus percentage time exceedance curve. A typical example for the Hunter River at Singleton is given in Figure 6. The ordinate or 'y' axis shows the instantaneous flow rate and the abscissa or 'x' axis gives the percentage time over which the particular flow is equalled or exceeded. It can perhaps best be visualised as a form of cumulative probability diagram. As a flow descriptor, it is far more useful than single value parameters such as mean or median discharge in that it evaluates all flow events from peak discharge floods to extreme low flows.

Tabulated flow duration data were obtained from the WRC. Whilst the tabulations were generally quite satisfactory in the 10 per cent to 90 per cent range, certain difficulties occurred at the very high and low flow extremes. The most rigorous method to input flow information would have been to develop discrete algorithms for each catchment. It was found that the mid range flows in most catchments could very satisfactorily be described by a function of the general form:-

Q = AeB where Q is discharge T is % time and A, B are constants.

At flows exceeded less than 10 per cent of the time, such a relationship seriously underestimated discharges. As will be discussed in some detail later, this would have led to significant errors in salt load estimates. It would have been quite possible to develop a three function algorithm for each tributary with boundaries at the 10 and 90 percentile time exceedances. However, this would have made model updating relatively tedious, and could well have discouraged a non-specialist user. It was therefore resolved that flows would be input as a series of ten decile values corresponding to the 5, 15, ---, 95 per cent times. Whilst not as accurate as a continuous algorithm, it is much easier to update when more gauging results become available.

High discharge values still had to be evaluated. The first attempts assumed that the peak discharge at To could be represented by Qi, or the flow that is exceeded on average once per year over a statistically long period of record. Integration under the resulting flow duration curve did not adequately correlate with measured average annual catchment yields. A more satisfactory procedure was found to be to use Simpsons Rule to fit a parabolic curve between known values and to extrapolate under high flow conditions whilst still preserving the correct catchment yields.

CONDUCTIVITY

Once flow data had been adequately entered, the next stage involved the input of conductivity information. Electricital conductivity gives an indirect assessment of the salt content of water. Pure water has relatively low conductivity. As the concentration of dissolved salts increases, the presence of charged ions raises the conductivity of the electrolyte. The magnitude of the change in conductivity varies directly with ionic concentration and the proportions of specific cations and anions. An approximate value of total dissolved solids (TDS) in water can be deduced from a knowledge of conductivity readings. 23

Raw data consisting of discrete conductivity/flow recordings were obtained from the WRC for each gauging station. The data were ranked by flow using a simple computer programme and converted to a conductivity versus time relationship for each tributary. Records were generally available on approximately a monthly basis, extending over about a ten year period. However, the intensity of sampling varied year to year as more sophisticated sampling equipment came into use. It was recognised that in some cases this would have led to heavier weighting being given to particular years, some of which were subject to drought conditions. To examine the representational adequacy of the conductivity information, a chi-squared test was applied. Individual recordings were deleted so that a minimum 99 per cent confidence limit was maintained.

To obtain a direct relationship between conductivity and time, a linear regression analysis was initially applied. There was found to be a good data fit for small tributaries, as demonstrated by the regression coefficient 'R'. The closer the regression coefficient is to plus or minus one, the more accurately data can be represented by a linear relationship. Typical values for small tributaries included Wybong Creek (R=0.92) and Dart Brook (R=0.90). However, as might have been expected for large catchments fed by multiple tributaries of differing qualities, regression coefficients for the main channel of the Hunter were markedly non-linear. At Muswellbrook for example, the regression coefficient was 0.06. There would appear to be no reason to expect strict linearity in favour of a more complex curvilinear relationship. In particular, departure from linearity seemed significant under high flow conditions in all tributaries. By imposing a linear correlation, salt loads would have been consistently overestimated. For the particular cases examined in detail, the overestimation was generally more serious for larger catchments than smaller ones.

It was decided to adopt an alternative approach of dividing all conductivity data into decile groups and assigning the arithmetic mean of the group as a typical value for all members of the group. This linked well with the adopted method of representing flows in that each tributary could then be represented by ten flow/conductivity data pairs. When conductivity data for a particular catchment could not be obtained, values from similar adjacent catchments were used. Areas that flow directly to the Hunter were assigned the same conductivities as the adjacent downstream tributary. This would be expected to slightly overestimate total salt loads, but not significantly affect total model accuracy.

SALINITY

To determine salt concentrations and salt loads, conductivity values had to be converted to total dissolved solids. The exact relationship will depend on the relative proportions of different cations and anions at each point in the river. In some areas, the majority of salts are calcium and magnesium bicarbonates, whereas elsewhere sodium chloride predominates (ref. 19).

Whilst conversion factors can vary from 0.45 to 0.85, waters in the Hunter basin usually range between about 0.59 and 0.69. A value of 0.65 has been adopted for the present study. Within a particular tributary there is 10 000

9000

8 000

7000

6000 0 (I, w

5000 z 4 000 0 -J U-

3000

2 000

1 000

0 20 40 60 80 100

PERCENTAGE OF TIME FLOW WAS EQUAL TO OR GREATER THAN INDICATED VALUE

FLOW DURATION RELATIONSHIP FOR HUNTER RIVER AT SINGLETON FIGURE 6 24

often a very close correlation between conductivity and salinity. Geary (ref. 10) for example found that in the Deep Creek catchment, a linear correlation between conductivity and TDS gave a regression coefficient of 0.99 over 130 samples.

The assignment of a constant conversion factor for conductivity will introduce some errors in TDS values, but these are not considered to be significant in view of the degree of scatter exhibited in conductivity/flow information. Once flow and salinity values have been established, instantaneous salt loads can be calculated as the product of flow and concentration. Total salt loads at any point can then be evaluated by summing instantaneous salt loads over time.

It should perhaps be emphasised that due to data shortcomings and various simplifications introduced in the analysis, the model can only give an approximate understanding of how the river system 'functions'. However, it is capable of being refined as more extensive monitoring data become available. As such, its predictive power and accuracy will be improved with time.

5.6 MODEL OUTPUT

A detailed documentation of the suite of computer programs and individual program listings are given in a separate user manual. Flow sheets of the model are presented in Figures 7 and 8. The manual specifies the nature and format of input data, so for brevity this information will not be repeated in the present section.

Various output options are available, depending on the needs of the user. In its most compact form, the model output can be restricted to a three page summary of the discharges and salt loads passing each junction node in the river. For each node, the average daily discharge in inegalitres per day is given, together with the average daily salt load in tonnes per day. Supplementary information includes decile flows exceeded from 5 to 95 per cent of the time, and the corresponding salt load for each decile flow. A typical example of the output is presented in Appendix 2.

Average daily salt loads as derived by the model are shown in Figure 9. The figure shows that the mean salt load at Singleton excluding salt added to the mainstream by groundwater is approximately 774 tonnes per day. As discussed in more detail below, groundwater entering the main channel of the river between the Goulburn River and Singleton accounts for a further average of 20 tonnes of salt per day. Total mean salt loads as observed at Singleton are therefore about 794 t/d or 290,000 t/y. The figure also notes an aspect reported in the Murray River Salinity Study (ref. 17), namely that although small tributaries can be highly saline, they may contribute little in terms of total salt tonnage to the river. It is the larger watercourses with relatively good quality water that often contribute the major salt loads. This is the dilemma facing those who advocate engineering controls as a means of intercepting salt before it reaches the river.

Overall, of the 794 tonnes passing Singleton per day, about 31.2 per cent 25

enters from the Goulburn River, approximately 39.2 per cent enters the river upstream of Denman, and the remaining 29.6 per cent enters between the confluence of the Hunter and Goulburn Rivers and Singleton. Between Denman and Singleton, major contributors are Glennies Creek and Wollombi Brook. Watercourses of high natural salinity such as Saltwater Creek and Bayswater Creek also contribute to total salt tonnage. The remaining tributaries only cause nominal salt increases.

Salt loads per se are of limited interest. Of more significance is the actual saline concentration of water. As discussed in Section 9, excess salinity reduces the productivity of irrigated crops, and in extreme cases can lead to plant toxicity. The general inverse relationship between flow and conductivity means that water quality is best in high flow conditions, and salt concentrations are highest under low flows. However, it is usually in times of low flows that river water is most needed for agricultural and other purposes. Therefore an appreciation of how salt concentrations vary under extreme weather conditions can be most helpful in understanding the salinity regime of a river. If it is required, the model can output individual decile flows and corresponding total dissolved solids for each tributary. These values are summarised in Tables 8 and 9.

As could be anticipated, there is a significant amount of scatter in conductivity values. This can be attributed to the relatively meagre amount of statistical data, and perhaps more importantly to the complexity of natural processes which are being modelled. Water can pass from surface flow to groundwater and vice versa between successive gauging points, river abstractions are variable, and antecedent weather conditions and localised microclimatic factors all complicate a deterministic analyses of salinity regimes.

The model multiplies Tables 8 and 9 to calculate salt loads under various flow conditions in each tributary. These are given in Table 10.

The model provides an indirect methodology for determining approximate groundwater accessions to the main stream of the Hunter River. As discussed in Section 2, Permian Coal seams form confined aquifers between sandstone and siltstone interburden. Where the seams outcrop or subcrop in the river or river alluvium, groundwater can discharge to the river. Although possibly not volumetrically important, such water is typically highly saline and contributes disproportionately to total salt loads in the Hunter. In a companion work to the present study, Australian Groundwater Consultants conducted a flow net analysis using observed potentiometric groundwater contours and assumed aquifer permeabilities to calculate groundwater accession rates to the Hunter (ref. 1). They determined that about 0.28 per cent of incident precipitation emerged directly as groundwater to the main channel of the Hunter between Muswellbrook and Singleton. If the average TDS of groundwater is assumed to be about 5000 mg/L, the quantity of salt which is added to the river can be calculated.

The present study considered the balance between salt inputs from surface tributaries and total salt loads at Singleton. Any shortfall could be attributed to direct mainstream groundwater accessions. On an average basis, the shortfall at Singleton is about 20 tonnes per day, or 2.5 per cent of the total salt load. This value would be quite sensitive to errors in tributary contributions, and the method can only be regarded as S

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[1

READ FLOW - CONDUCTIVITY DATA

SURF 1:0W CONDUCTIVITY DATA INTO )ESCEND I NC ORDER BY F LOWS

DIVIDE SORTED FLOW - CONDUCTIVITY S DATA INTO ULC1 LU GROUPS

CALCULATE MEAN DECI LE TOTAL OISSOLVEII SALTS

S READ AVERAGE CATCIIMEN'F YIELD

READ FLOWS FOR IERCENTI LED 10 to 100 AS DETERMINED FROM FLOW DURATI ON CURVE

1ST IMA'FIi TIE FLOW AT PERCENT I CE 0

CALCULATE DUCT LU WATER YIELDS BY INTEGRAFI UN OF FLOW OURAT iON CURVE S

CALCULATE OI,CI I.E I MI-AN SA!;F lOADS

WRITE DECI CE YIELDS I SALT LOADS TOJ S FLOW CHART FOR HUNTER RIVER SALINITY MODEL -SHEET 1 FIGURE 7 5 [1

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READ CATCHMENT DATA

READ NODE OPERATION

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READ INPUT NODE 1, INPUT NODE 2, OUTPUT NODE, PRINTING FLAG, Ll NODE IDENTIFIER

PERFORM NODE OPERATION fl

PRINT DECILE YIELD AND SALT LOAD IF PRINTING FLAG SET

FLOW CHART FOR HUNTER RIVER SALINITY MODEL-SHEET 2 FIGURE 8 e . 0 S

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approximate. When corrected for the differing river reaches being considered, the AGC results gave rather higher values of about 60 tonnes per day or 7.5 per cent of total river salt loads. Although higher, they are still the same order of magnitude as those determined from the model output.

It will also be appreciated that the above values only refer to main stream accessions, not total groundwater accessions. Much of the salt load from tributaries could be expected to have been derived from springs and other connections to underground aquifers. The regional significance of groundwater as a vehicle for the transport of salt would therefore be far higher.

Direct groundwater accessions are of most concern during low flow conditions in the river. Coal seams typically have a relatively low in situ permeability. This is apart from localised discontinuities such as joints or faults associated with major folding or other geological disturbances. Aquifer flow rates are dependent on both available hydraulic heads and seam permeabilities. Flow velocities of around one metre per year would not be unusual. Velocities would be relatively independent of short term seasonal weather conditions. Salt loads contributed by direct groundwater accessions would therefore be substantially constant over time. Under high flow conditions associated with wet weather, groundwater salt loads would be diluted by surface runoff. During droughts, they would form a higher proportion of total salt loads.

Whilst the preceding analyses is able to quantify the total direct contribution of groundwater to salinity levels, it is not able to identify at what points the salt actually enters. To establish this information, a far more detailed mainstream monitoring programme would be needed. Whilst the Water Resources Commission has undertaken a certain amount of longitudinal monitoring, insufficient data has been made publicly available to permit major accession points to be located. For purposes of the present study groundwater was arbitrarily assigned to upstream junction nodes to make intermediate mainstream values as meaningful as possible.

11

U 27

46

. TABLE 8

- TRIBUTARY DISCHARGES (ML/d)

Percentage Time Exceedance IA Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 1554 253 92 62 40 28 18 13 6 2 Glenbawn 2121 530 384 298 220 166 116 74 36 11 . Rouchel Brook 1100 144 78 44 32 22 14 6 2 - Dart Brook 800 121 57 15 5 2 1 - - - Muswellbrook 6440 1367 784 567 450 358 269 202 120 45 Hunter upstream Goulburn 6558 1395 798 578 458 365 274 206 122 46 Goulburn upstream Sandy Hollow 3998 381 201 122 84 57 33 15 2 - Wybong Creek 859 108 73 50 37 25 20 12 7 3 Goulburn upstream Hunter 4857 489 273 172 120 82 52 26 9 3 Martindale Creek 576 46 25 14 7 3 - - - - Saddlers Creek 135 6 4 2 2 1 - - - - Doyles Creek 277 16 7 4 2 1 - - - - Saltwater Creek 98 4 2 1 ------Bayswater Creek 118 28 24 21 18 15 11 8 5 2 Bomians Creek 205 65 29 13 9 2 - - - - Glennies Creek 1682 238 119 76 49 28 19 4 - - Wollombi Brook 2351 301 148 96 60 41 24 13 2 - Ll Loders Creek 122 5 2 2 1 1 - - - - Singleton 17722 2835 1408 898 561 347 221 141 90 57 Mudies Creek 577 7 3 2 1 1 1 - - - Jump up Creek 361 2 1 1 ------Glendon Brook 405 91 38 21 13 6 5 2 - -

rA e

TABLE 9 TRIBUTARY SALINITIES (nig/L)

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 263 609 563 480 490 221 404 669 686 834 Glenbawn 200 235 235 175 225 242 223 264 295 293 Rouchel Brook 273 333 270 325 429 292 311 258 315 364 Dart Brook 269 381 349 558 744 1252 1416 1269 1281 1307 Muswellbrook 274 347 291 264 289 271 292 315 356 407 Hunter upstream Goulburn 275 346 290 265 289 271 292 315 356 406 Goulburn upstream Sandy Hollow 306 565 564 608 616 683 668 677 795 795 Wybong Creek 607 456 507 768 748 813 814 822 1089 1030 Goulburn upstream Hunter 359 540 549 651 667 720 731 769 1111 1000 Martindale Creek 173 201 332 356 432 508 1308 1308 1308 1308 Saddlers Creek 903 2386 3868 3683 3991 4298 4541 4879 4879 4879 Doyles Creek 157 237 264 404 400 434 442 497 788 1052 Saltwater Creek 3900 4506 5111 4826 4540 5244 3871 6825 6825 6825 Bayswater Creek 1030 1006 981 957 1040 1124 1207 1290 3300 3637 Bonans Creek 144 529 797 744 768 1271 1885 1885 1885 1885 Glennies Creek 129 247 369 310 341 327 471 555 621 621 Wollombi Brook 157 237 264 404 400 434 442 497 788 1052 Loders Creek 220 518 609 574 641 595 766 730 826 842 Singleton 266 432 540 580 480 523 530 502 546 611 Mudies Creek 220 518 609 574 641 595 766 730 826 842 Jump up Creek 220 518 609 574 641 595 766 730 826 842 Glendon Brook 220 518 609 574 641 595 766 730 826 842

e 29

TABLE 10 DAILY SALT LOADS (tonnes/day)

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95 Average

Pages River 409 154 52 30 20 6 7 9 4 2 69 Glenbawn 424 125 90 52 49 40 26 20 11 3 84 . Rouchel Brook 300 48 21 14 14 6 4 2 - - 41 Dart Brook 215 46 20 8 4 2 1 - - - 30 Muswellbrook 1766 474 228 150 130 97 78 64 43 19 305 Hunter upstream Goul burn 1803 483 232 153 133 99 80 65 43 19 311 Goulburn upstream [1 Sandy Hollow 1223 215 113 74 52 39 22 10 2 175 Wybong Creek 521 49 37 38 28 20 16 10 8 3 73 Goul burn upstream Hunter 1744 264 150 112 80 59 38 20 10 3 248 Martindale Creek 100 9 8 5 3 2 - - - - 13 Saddlers Creek 122 14 15 7 8 4 - - - - 17 . Doyles Creek 43 4 2 2 1 - - - - - 5 Saltwater Creek 382 18 10 5 ------42 Bayswater Creek 122 28 24 20 19 17 13 10 16 7 28 Botmans Creek 30 34 23 10 7 3 - - - - 11 Glennies Creek 217 59 44 24 17 9 9 2 - - 38 Wollombi Brook 369 71 39 38 24 18 11 6 2 - 58 Loders Creek 27 3 1 1 1 1 - - - - 3 Singleton 4714 1225 760 521 269 182 117 71 49 35 794 Mudies Creek 127 4 2 1 1 1 1 - - - 14 Jump Up Creek 79 1 1 1 ------8 Glendon Brook 89 47 23 12 8 4 4 2 - - 19 IA

19 COLUEY WATER BALAICES

SECTQ! .

30

6. COLLIERY WATER BALANCES

6.1 THE CONCEPT OF WATER BALANCE

Water is one of the resources necessary for the mining and beneficiation of coal. A certain amount of water is produced on a mine site and it is consumed in a multiplicity of ways during the extraction and washing of coal. A water balance seeks to predict, under varying meteorological conditions and stages in the life of a mine, whether or not more water will be produced than consumed. A positive balance signifies that water is produced in excess to requirements and that some form of water disposal will be needed. Conversely a negative balance indicates an overall site deficit. In this case water would have to be brought in from an external source such as a lake or river to satisfy demands. Most operating mines can have shortages and surpluses of various types of water at different times throughout a year.

Whilst the basic concepts of a water balance are quite simple, the number of independent variables render calculations so voluminous that computer techniques are called for. A further complication is that whilst there may be no overall site imbalance, there can be shortages or excesses in various classes of water. As part of the present study, a computer based water balance model was developed to quantify discharge requirements for typical Hunter Valley mines.

6.2 COLLIERY PROPRIETORS QUESTIONNAIRE

To gather baseline data on present mines plus all those planned to commence production within the next decade, a questionnaire was circulated to all members of the New South Wales Coal Association with interests in the Upper Hunter. The survey sought information on a year by year basis for the period 1985 to 1994 inclusive. A copy of the survey sheet and instruction page is reproduced in Appendix 1. The survey was distributed by mail, and both personal and telephone contact was maintained to assist members in completing the questionnaire's data schedule. Information was requested on the following matters:

- Run-of-mine output, Mt/a - Washed coal output, Mt/a - Capacity of washery, t/h - Washery makeup requirements, L/t RUM coal - Groundwater make, ML/d - Salinity of groundwater, mg/L - Cumulative capacity of mine water dams, ML - Cumulative capacity of surface dams, ML - Plan area of pit exposed, ha - Plan area of surface facilities, ha - Plan area of out-of-pit overburden, ha - Plan area of rehabilitated mine areas, ha - Unmined area, ha - Area of out-of-pit haul roads, ha

Ell 31

- Area watered in pit, ha - Surface area of coal stockpiles, ha - Maximum tolerable salinity in washery, mg/L.

Responses were supplemented by published Environmental Impact Statements or other studies conducted at particular mines where these were made available. Whilst most companies were quite co-operative in completing the questionnaire and a great deal of useful information was collected, the final result was by no means exhaustive. A good number of operators were only, able to give order of magnitude values to most of the queries. Older mines had never found the need to record much of the data requested, and the mines still at the planning stage could only provide general estimates of parameters such as groundwater inflow rates, overburden rehabilitation areas and other necessary inputs.

6.3 WATER MANAGEMENT STRATEGIES

Each mine has a unique set of determinants such as location, deposit geometry, coal quality and hydrologic characteristics. The water management programme most appropriate for each application will be specified by these determinants and will vary from mine to mine. However, certain management strategies are usually common to all programmes. They are:

waters of different quality should be segregated

- priority in on-site consumption should be given to the poorest quality water

- saline waters should only be released when they are able to be assimilated by the surrounding environment

- water should be conserved to reduce demands on external supplies and hence to reduce competition with other water consumers.

6.4 WATER SUPPLY AND CONSUMPTION

To commence a water balance analysis, all sources of water are catalogued by class of supply. Conventionally there are at least six classes of supply, including the following:

* Uncontaminated Upstream Runoff

This is often simply diverted around mining operations and returned to downstream watercourses. Where possible, it is becoming more common to harvest a proportion of this runoff in storage reservoirs for subsequent on-site use. 32

* Mine Pit Water

Pit water includes groundwater inflow and in the case of opencut mines, storm runoff from the floor and sideslopes of the workings. Much of this water is lost by evaporation, but the remainder gravitates to low points of the pit from which it is pumped to mine water dams. Water quality is variable, but is often high in salinity and when first collected, also high in suspended solids. It is used for dust suppression and washery makeup.

* Runoff and Washdown Waters from Surface Facilities and Coal Stockpiles

Washdown water consists of effluents from vehicle washdown bays and workshop hosings. It contains mud and other suspended solids with a proportion of oil and grease. This water is collected and passed through grit and oil arrestors for purification. Coal stockpile runoff contains fine coal particles which are removed by sedimentation dams.

* Runoff from Roads and Unrehabilitated Overburden

Surface runoff is normally low in salinity but high to very high in suspended solids. It is directed to sedimentation dams for clarification. The clarified water is either recycled, or displaced into receiving watercourses during storms.

* Sewage and Bath House Effluents 40 Sewage and effluents from bath houses, lunch rooms and ablution facilities are collected and passed to some form of treatment works. Smaller operations are usually treated in septic tanks followed by biological filtration in absorption trenches. Larger mines can often justify the installation of extended aeration package treatment plants, followed by effluent polishing in maturation ponds. Treated effluent is then disposed by spray irrigation or by watering amenity landscaping.

* External Supplies

When other supply sources are not adequate to meet total on- site requirements, makeup must be drawn from external supplies. These include river abstractions, common user pipelines and town supplies. Potable water requirements are relatively modest, and can often most conveniently be met from town supplies even where a mine has a positive water balance.

The complimentary input data needed for commencing a water balance is a full schedule of water requirements. All consumptive water uses are catalogued as follows:

db 40 33

* Washery Makeup Water Ll

The quantity of washery makeup needed will depend on the incoming coal quality, final product specifications, tailings disposal methods and degree of recycling within the plant. The permissible quality of makeup water is a function of treatment technologies adopted and the corrosion resistance of materials used in the design of the washery. Fluctuations in feed water quality can be more difficult to cope with than high but constant salinity values.

* Haul Road Dust Suppression

Water is used for dust suppression on haul roads and in-pit working areas. Pit water is used preferentially.

* Coal Stockpile Dust Suppression

It may be necessary in some weather conditions to spray coal Ll stockpiles with water to reduce dust emissions. To conserve water, chemical suppressants are sometimes also specified.

* Potable Supplies for Staff Amenities

Potable water is consumed in bath houses, lunch rooms and in 40 ablution blocks.

* Vehicle and Workshop Washdown Water

Water is required to wash haulage vehicles before allowing them onto public roads. Mine vehicles are also washed prior to mechanical maintenance. A small volume of water is consumed hosing workshop and washery floors.

* Amenity Landscape Irrigation

Landscaping around workshops, site offices and amenities are often maintained by watering from a fixed irrigation system. . Advantage can be taken of the nutrients in treated sewage by using effluents from maturation ponds for landscape irrigation.

* Dam Evaporation

Water is 'consumed' in the sense of being lost for recycling by direct evaporation and leakage of storage dams. In the Hunter Valley this represents a small but quantifiable amount of total water requirement.

6.5 COMPUTER SIMULATIONS

Apart from its ability to manipulate large quantities of data, a computer affords the opportunity of quantifying the adequacy of water pollution

lb 34

safeguards. Where there are gaps in our understanding of the detailed hydrological operations of a mine, a range of values can be tested to give an appreciation of the sensitivity of input parameters. These can be refined as more monitoring data and research expand our knowledge. Alternative development strategies for mines can be modelled relatively easily, and the implications of increased sophistication in water pollution controls can be determined.

The water balance model used for the present study is documented in a separate user manual. A flow sheet of the programme logic is given in Figure 10. Input requirements for the model are shown in the manual, and the reader is referred there for a more detailed discussion of the various parameters. In summary, it is necessary to input basic mine parameters, some of which will change over the life of the operation whilst others will remain constant. Data requirements include pit areas, workforce numbers, surface facilities areas, haul road lengths both in-pit and out-of-pit, dam capacities and overburden areas. Runoff or yield coefficients must be assigned for each type of catchment surface. S One of the major variables affecting water balances is the prevailing meteorological conditions. Variations in rainfall and potential evaporation can significantly influence whether surpluses or deficits are experienced. Long term rainfall data on a daily basis is available at a number of recording stations throughout the Hunter Valley. Records extend back as far as 1871 in some instances, and the network of stations allow a reasonable understanding to be obtained of local meteorological conditions. Unfortunately, much less information is available on long term potential evaporation. Older records can be subject to significant error, and there are few adequately located stations with contemporary Type A evaporation pans. Records are often restricted to the previous 10 years or less. S Therefore in general, whilst rainfall data is usually adequate, the lack of long term evaporation data may limit the accuracy of any water balance model.

There are two alternative approaches to modelling meteorological data. The first involves statistically analysing the recorded data and producing S various statistical summaries. These could include such values as mean, median, 10 percentile and maximum recorded rainfall. These results are then applied to each year of the mine and excesses and deficiencies identified. This method has several inherent limitations. The volume of water carried forward year to year in dams has little physical meaning. Such a procedure does not account for large month to month fluctuations that occur under actual operating conditions. There is a 'smoothing' of the data, or reduction in its variability. Finally, it is difficult to interpret extreme annual events. A one in ten year draught can be evaluated, but its serial application every year for 20 years of a mine's life would be a compounding of probabilities that would have an extremely remote chance of occurring in practice. S The second approach to meteorological monitoring, and the one adopted in the present report is to input raw historic data and to 'step' the mine through each year. This is best explained by way of an example. Suppose 40 years of meteorological data are available and an examination of a mine with an operating life of 20 years is wanted. The first year of the mine S would be considered to coincide with the first year of records, and the end

0 35

of the mine with the twentieth year of records. A complete monthly water 10 balance would be conducted to determine what quantity of water is required by the mine each month, and what quantity would overflow from each dam. That is, the output of each dam would be monitored 240 times over the life of the mine.

When the balance is completed, the mine would be stepped by a year such that it commences on the second year of meteorological records and finishes on the twenty first year. The next set of runs would commence on the third year and end on the twenty second year. This process would be repeated twenty one times, so that each dam would be monitored 21 x 240 or 5,040 times. The results are then statistically analysed to produce data appropriate for safeguards design or impact analysis.

To improve the accuracy of this procedure, various techniques could be applied to artificially extend the length of meteorological records. One way would be to rearrange the years of records in different sequences. Forty sets of annual data could be rearranged in about 8 x 10 different ways. However, rearrangement in random sequences would destroy the cyclic nature of weather patterns. Drought years tend to group together, and they recur in defined cycles. Random ordering would therefore tend to underestimate the seriousness of both drought and peak rainfall conditions.

It is also possible to mirror or loop records to preserve multi-year cycles but still to provide longer records. The particular technique used in the 0 present study involves record looping to allow equal weighting to be given to each year of records. With a single sequence discontinuity, the model is able to examine in the example given 41 separate mine scenarios. Each dam in that case would be monitored 41 x 240 or 9,840 times. Output is accumulated and statistically analysed as the programme is run, both on a monthly basis and an annual basis. Results can be presented in any form 0 that the user requires. In the present instance, average discharges and those exceeded 10 per cent and 90 per cent of the time have been selected.

6.6 MODEL APPLICATION

It would have been beyond the brief of the present study to individually model each proposed mine in the Upper Hunter. Furthermore, this level of detail did not appear warranted as many proprietors were only able to give order of magnitude values to most of the necessary input variables.

Older mines had very little information, and the mines still being planned only had estimates of inputs such as groundwater inflow rate's, overburden rehabilitation areas, etc. It was therefore resolved that two or three mines would be modelled, and the results generalised to account for the simultaneous actions of all mines. The most direct correlation between water excesses and mine size was assumed to be either total overburden production or run-of-mine coal production.

A number of mine leases or authorisation areas straddle more than one catchment. The percentage and type of water discharged to each subcatchment would vary over the life of each mine. For purposes of the present study, it has been assumed that total discharges from each mine are

Li HIHiHHH HHi H :)411

0 0

FLOW CHART FOR MINEWATER BALANCE MODEL FIGURE 10 36

allocated to individual subcatchments on the same ratio as the area of mine lease or authorisation contained within that subcatchment. The allocation of mines to model subcatchments is given in Figure 11. Whilst this assumption may not exactly match the discharge points of individual mines, the overall effects on mainstream salinity concentrations would not be expected to be serious.

6.7 WATER BALANCES FOR INDIVIDUAL MINES

Three mines were selected for detailed water balance analyses. The mines were selected by the quality of available input data, the size of the operations, their similarity to other mines and their location in the Hunter Valley basin. Details of the three mines are given in Appendix 3. No attempt was made to optimise pollution controls to alter the quantities of water discharged. Where dams were too small, they were not adjusted and no special control techniques were assumed. These techniques, including in-pit evaporation and holding water in-pit are described in greater detail in Section 8. The water balances could therefore be considered as being representative of modern collieries with normal water pollution controls.

The results of the water balance modelling are summarised in Table 11. • TABLE 11

MINEWATER SURPLUSES UNDER VARYING METEOROLOGICAL CONDITIONS (ML/month)

Frequency of Occurrence MINE A MINE B MINE C

10 percentile 60 116.7 100 Average 12 23.3 20 90 percentile Nil Nil Nil

Where: * 10 percentile is the water surplus exceeded 10 per cent of • the time over a statistically long period * Average is the arithmetic mean of all water surpluses

* 90 percentile is the water surplus exceeded 90 per cent of the time over a statistically long period.

Model output can be used to predict makeup water demands, or the quantity of water which would need to be drawn fom external sources to satisfy site requirements under varying weather conditions. The magnitude of these demands is a function of the size of on-site reservoirs and the efforts taken to harvest clean water. It also depends on the degree of recycling practised and the standards imposed for dust suppression. It would be 37

beyond the scope of the present study to analyse these variables in any detail. However for the conditions specified in the water balances, supplementary annual water requirements are given in Table 12.

TABLE 12

AVERAGE ANNUAL VOLUME OF MAKEUP WATER (ML/a)

MINE A MINE B MINE C

180 1380 1377

To quantify the impact of minewater discharges, a weighted average surplus was calculated for the three mines considered. The adopted value per million tonnes of ROM coal is shown in Table 13.

TABLE 13

MINEWATER SURPLUSES PER MILLION TONNES ROM PRODUCTION

Period Volume (ML/month)

10 percentile 16.67 Average 3.33 90 percentile Nil

Even when a surplus occurs, it may still be necessary to obtain water from external sources to satisfy potable demands. (AbOVE Rouchel Brook Hunter River

BeLlombi(Dartbro aeS River

gQ% Mt. Arthur N -th Muscle Creek 50% Mt Sugar loaf 50% (MUSLL8FW( Mt. Sugar!oaf I Hunter R 10 e4AN) 50% Drayton Y---=W bo:n~: Creek 80% Bayswater, I Ulan Goutburn River

10% Mt Arthur North Martindale Cree 20% Drayton 20% Bayswater f-poyles Creek

50% Mt. Arthur South Hunter ValleyN01 50% Mt. Arthur South 90% Hunter Vahey 50% Howick 20% BBC

30% Drayton 50% Ravensworth N°2 50% Ravensworth N°2 Pikes Gully Boyswater Liddelt Glendell Bowmans eek Liddell State Foybrook Foybrook North 50% Howick Swamp Creek

Bloomfield 50% BBC United jJ% Warkworth Worn bo 70% Saxonvale - 60% Warkworth 50% Newcastle -Eorn Brook Wallsend(Bulga) 50% Mt.Thorley

50% Newcastle - 50% Mt, Thorley Wallsend(Butga) 30% Saxonvale 10% Hunter Valley N°2 Barix (Great Greta) Barix (Mitchelts Flat)

PERCENTAGES OF LEASE OR AUTHORISATION AREAS WITHIN EACH SUBCATCHMENT FIGURE 11 CONSEQUENCES OF EXPAN SON HN COAL VNNG

SECTION 7

7. CONSEQUENCES OF EXPANSION IN COAL MINING

7.1 INCREASES IN WATER DEMANDS

One of the consequences of an expansion in the coal industry, as outlined in Section 3, would be an increase in total demand for makeup water. This water would ultimately be drawn from the Hunter River or its tributaries. Volumetric requirements are governed partly by weather conditions, and partly by policy decisions such as the application rate for dust suppression and the type of washery processes and tailings recovery systems used. An exhaustive assessment of different usage strategies would be a full study in itself. However, an approximate appreciation of gross makeup needs can be obtained from the final part of the previous section. Mine A is slightly unusual, in that it has a relatively high groundwater intake and extensive recycling is practised in the coal preparation plant. The other two mines give annual makeup quantities of 200 and 230 L/ROM tonne respectively. With a total RUM production of some 92 MT/a, average annual water requirements would therefore be in the range of 18,400 to 21,200 ML/a.

This can be compared with the value adopted by the Water Resources Commission in preparing its 1982 review of water requirements (ref. 28). The Commission adopted a volume of 400 litres per product tonne. At present a coal product recovery rate of 70.1 per cent is achieved on the raw coal washed in the Singleton-North West Coalfields (ref. 14). Assuming that most new mines would wash their output, this implies an approximate water usage of 280 litres per RUM tonne. Annual requirements would therefore be about 25,800 ML. The Commission's estimate does not allow for changes in consumption due to differing weather conditions, but instead assumes a constant usage.

7.2 DISCHARGE REQUIREMENTS

One purpose of the suite of computer programs developed for the present study is to examine the cumulative impact of various levels of mine discharge on water quality in the Hunter. To quantify this impact, the minewater surpluses per million tonnes of RUM coal have been taken from Table 13. They have been distributed to tributaries and reaches of the Hunter in accordance with Figure 11 and Table 14. The resulting flows have then been assumed to directly discharge with no further controls. The resulting inputs per tributary are given in Table 15. Daily flows have been calculated as one thirtieth of individual monthly flows. Salt loads have also been calculated on the basis that average pitwater salinity is about 1500 mg/L. Groundwater is diluted by direct precipitation, and monitoring of actual minewater dams indicates that the adopted figure is a reasonable estimate for an operating mine.

The salt loads added to each reach of the Hunter River are given in Table 16. Under ten percentile conditions, minewater discharges increase about fivefold, but pit salinity would decrease due to greater dilution from rainfall. A reduced saline concentration of 1000 mg/L has been used as model input for this case. 39

TABLE 14

RUN-OF-MINE PRODUCTION BY TRIBUTARY 1994

Tributary Production (Mt/a)

Dart Brook 7.0 Muscle Creek 3.33 Hunter River upstream Denman 12.78 Goulburn River 6.2 Saddlers Creek 5.0 Saltwater Creek 5.98 Hunter River above Bayswater 5.76 Bayswater Creek 7.23 Bowmans Creek 9.46 Glennies Creek 1.4 Wollombi Brook 15.67 Loders Creek 10.12 Glendon Brook 2.5

Total 92.43

7.3 CUMULATIVE IMPACTS OF MINEWATER DISCHARGES

The cumulative impacts of discharged waters can be assessed by the magnitude of changes caused to flows and salinity concentrations under various river conditions. Alterations to volumetric flows in the river as a result of mine discharges would be of minor significance except during low flow conditions. Changes in salinity can be of greater importance. Salinity values have been calculated for ten different flow conditions in each reach of the Hunter under four discharge regimes. The results are somewhat voluminous and are therefore reproduced in Appendix 5. A typical result downstream of the Bayswater Creek tributary is given in Table 17. Under high rainfall conditions, although minewater volumetric discharges increase about fivefold and salt discharges over threefold, the receiving waters allow greater dilution. Analysis of seventy years of flow records at Singleton show that the annual flow in the Hunter River exceeded ten percent of the time is approximately 234 per cent of average annual flow. Flows and salt loads under high annual discharge regimes were assessed. These are also given in Appendix 5.

Table 17 summarises data given in Appendix 5, Tables A5.2 and A5.4. No changes occur to river water quality in years of lower rainfall as mines do not need to discharge water in these conditions. S

Ll TABLE 15

DISCHARGES OF MINEWATER FROM ALL PROJECTED MINES IN 1994 (ML/day)

Tributary or Reach 10 Percentile Average 90 Percentile

Dart Brook 3.85 0.77 Nil Remainder upstream of Muswellbrook 1.80 0.36 Hunter Muswellbrook to confluence 7.00 1.40 Goulburn River 3.40 0.68 Martindale Creek Saddlers Creek 2.75 0.55 Saltwater Creek 3.30 0.66 Hunter above Bayswater 3.15 0.63 a Bayswater Creek 4.00 0.80 Bowmans Creek 5.20 1.04 Glennies Creek 0.75 0.15 Wollombi Brook 8.60 1.72 Loders Creek 5.50 1.10 Glendon Brook 1.35 0.27 a Total Minewater Discharge 50.65 10.13

TABLE 16

SALT LOAD FRUM ALL PROJECTED MINES IN 1994 (tonnes/day)

Tributary or Reach 10 Percentile Average 90 Percentile

Dart Brook 3.83 1.15 Nil Remainder upstream of Muswellbrook 1.83 0.55 Hunter Muswellbrook to confluence 7.00 2.10 Goulburn River 3.40 1.02 Martindale Creek Saddlers Creek 2.73 0.82 Saltwater Creek 3.27 0.98 Hunter above Bayswater 3.17 0.95 Bayswater Creek 3.97 1.19 Boiians Creek 5.17 1.55 Glennies Creek 0.77 0.23 a Wollombi Brook 8.57 2.57 Loders Creek 5.53 1.66 Glendon Brook 1.37 0.41

Total Salt Discharge 50.61 15.18

i 41

TABLE 17 [1 SALINITY OF HUNTER RIVER BELOW BAYSWATER CREEK WITH MINEWATER DISCHARGES (mg/L)

Discharge Situation Percentage Time Flow is Equalled or Exceeded in Hunter River 5 15 25 35 45 55 65 75 85 95

No discharge 342 413 389 384 402 379 389 396 507 569 10 percentile 274 335 319 317 336 327 335 350 456 564 Ll Average 343 416 395 392 412 393 408 422 548 664 90 percentile 342 413 389 384 402 379 389 396 507 569

IA At Singleton the percentage increase in salinity ranges from 0.2 per cent with discharges during high river flows, to 34.4 per cent with discharges in low river flows.

The output given in Appendix 5 clearly indicates the effects of discharging minewater under a variety of weather conditions. Two types of impact should be considered. The first relates to changes in mainstream salinity values, and the second relates to changes in salinity within a particular tributary upstream of its confluence with the Hunter River.

Tables A5.2 and A5.4 show that except under very low flow conditions, salinity concentrations in the mainstream of the Hunter River are only slightly affected by the simultaneous discharge of minewater from all projected coal mines. The implications of this are that provided discharges are avoided for one to two months in a year, there would be little adverse impacts on the Hunter itself from the regulated direct discharge of minewater excesses.

Salinity levels in individual tributaries can be more sensitive to discharge conditions. In some naturally saline tributaries, the discharge of minewater can actually lead to improvements in stream water qualities. This can be seen for example in both Saddlers Creek and Saltwater Creek (refer to Tables A5.1 and A5.3). However, in other tributaries relatively large percentage changes in salinity occur, especially in medium to low flow conditions.

It would therefore be rational to regulate mine discharges on an individual tributary basis by considering the sensitivity of that tributary's water quality, its background conductivity and the numbers and types of downstream users. Controls would need to be more rigorous on some tributaries, but can reasonably be relaxed on others. TREATMENT AND DISPOSAL OF SALINE WATER .

[1 42

8. TREATMENT AND DISPOSAL OF SALINE WATER

8.1 OVERVIEW

As indicated in Section 2, the origins of salinity in the Hunter River are primarily determined by geology. The majority of salt in the Valley, particularly sodium chloride salt, is derived from sedimentary Permian strata. Land use is one factor that influences the rate at which soluble compbnents are leached from the sedimentary strata into receiving watercourses.

Coal mining per se does not create salt. Mines intercept saline aquifers and by locally increasing hydraulic gradients, cause short term increases in aquifer flow rates. If discharged directly to rivers, this can result in elevated salinity concentrations in downstream reaches. Below certain concentrations, this increased salinity may not affect either the natural ecosystem or downstream water users. At higher concentrations, impacts could be experienced by residential, agricultural and industrial consumers. To avoid these consequences various measures are available to control and safely dispose of saline minewater. A selection of these measures are discussed in the remainder of this section.

8.2 DISPOSAL ALTERNATIVES

There are three broad strategies for the control of salt from mining. The first involves the management and re-use of water on site so that no water excesses are created. By containing water on the mine, no salt can be carried into receiving watercourses. Generally this environmentally sound strategy is the most effective. Maximising the use of water generated within the mine has the additional benefit of reducing makeup quantities from external sources.

Although conservation and re-use is a valuable strategy, it will often not cope with all the minewater generated under adverse weather conditions. Two other approaches can then be considered; the containment of all salt on site, or the release of saline waters in such a way that they can be assimilated by receiving watercourses without adversely affecting the environment. Examples of the former include evaporation and in-pit burial of concentrated wastes, and desalination. Strategies for controlled release of salt include stage discharge, deep well injection and transport by pipeline to suitable receiving watercourses. Each of these measures is described below.

8.3 STAGED DISCHARGE

A staged discharge programme is a strategy which relies on the dilution capacity of a river in medium to high flow conditions. Water is contained on site when river flows are low and the salinity of the river is highest. During and following storms when flows increase, stored water is released

0 43

in a controlled manner in accordance with a predetermined river management strategy.

The method utilises a knowledge of natural drainage catchment processes obtained by water quality monitoring and hydrologic modelling. It recognises that the most effective transport system for excess minewater is the river itself. It entails the construction of substantial storages at each colliery and it can require the ability to hold water in-pit for periods following heavy rain. Such water must be monitored for both quanjity and saline concentrations. An awareness of flows and water quality in the receiving tributary and the Hunter River itself would also be needed. Whilst an individual colliery could operate such a system within parameters agreed to by the SPCC and the WRC, it would appear more effective for all coal mining operators to respond to a catchment management programme operated by the WRC. Releases could be ordered in much the same way as irrigation demands are now requested. It is envisaged that irrigation requirements, reservoir releases, mine discharges and major abstractors would be co-ordinated with river flow, rainfall and conductivity information in a comprehensive catchment management plan.

8.4 TRANSPORT BY PIPELINE TO SUITABLE RECEIVING WATERS

One suggestion for the disposal of saline minewater has been to construct a pipeline from the Upper Hunter to the estuarine reaches of the river downstream of Maitland. The scheme would involve the construction of some 90 to 100 km of trunk pipeline. Minewater from individual collieries would be pumped to a central collection reservoir before being disposed of via the trunk pipeline. A suitable reservoir may possibly be formed from the final void of an opencut mine. Alternatively, suitably located mines could discharge directly into the pipeline along its length.

To gain an approximate understanding of the throughput capacity and costs of such a scheme, certain operating parameters have been assumed. To avoid peak hour energy charges, pumping has been restricted to 20 hours per day. It has further been estimated that pumping would occur for an average of 350 days per year, to allow for maintenance and other non-operating conditions. The approximate annual throughput of various size pipes is given in Table 18.

TABLE 18

ANNUAL CAPACITY OF PIPELINES

Diameter (mm) Annual Capacity (ML/y)

150 890 200 1580 250 2475 300 3560 44

This can be reviewed against the flows in the river itself. The average annual flow at Singleton is 887,000 ML/y, and the annual salt load is about 290,000 tonnes per year. If the average salinity of pit water is increased to 2000 mg/L, the percentage flow and salt load carried by the pipeline when compared with the Hunter River is given in Table 19. S TABLE 19

FLOW AND SALT LOAD IN OUTFALL PIPELINE COMPARED TO HUNTER RIVER

Pipe Diameter Percentage of Total Percentage of Total (mm) Average Flow Average Salt Load

150 0.1 0.6 200 0.2 1.1 250 0.3 1.7 300 0.4 2.4

It can be seen that a pipeline of the sizes given would only marginally affect salt loads in the river.

To keep pipeline operating pressures within reasonable limits, a series of booster pump stations would be needed along the length of the outfall. Order of magnitude capital cost estimates were prepared for each pipe size.

The total cost of the trunk pipeline, intake pumps and boosters would range from about $9 Million to $17 Million, depending on pipe diameter. In addition, subsidiary mains would be needed to convert individual mines or groups of mines to the trunk system. It could be expected that the subsidiary connections would increase capital costs to between $15 Million and $25 Million. This excludes such items as easement acquisitions, services relocations and legal costs.

8.5 DEEP WELL INJECTIONS

This method has been successfully used in situations where substantial permeable aquifers underlie a site, and where no unacceptable contamination of aquifers would occur. Applications in the literature extend not just to the disposal of brines, but also radioactive wastes, cheese factory effluents and other liquid industrial wastes.

There are two main forms of aquifer in the Hunter Valley. The first is contained in a relatively narrow band of river alluvium which forms an unconfined aquifer linked directly with the river. There would appear to be little benefit gained by injecting saline minewater into the alluvium. Such water would gravitate directly to the river and less control could be exerted over its rate of accession to the Hunter than if direct discharge methods were employed. Also, alluvial bores are an important source of water for stock and irrigation. Their contamination with more saline

41 0 45

waters with limited opportunities for dilution from surface sources would appear to be counterproductive.

The second major aquifer type in the Hunter Valley is the Permian coal seams. These form a series of confined aquifers with sandstone and siltstone interburden acting virtually as aquitards. Groundwater in the coal seams is saline, and the reinjection of minewater would not adversely affect its quality. However, coal seams usually have comparatively low permeability. The gross permeability is a function of depth, coal type, degree of faulting and weathering. In areas of geological discontinuity where strata are folded or intersected by dykes, permeabilities can locally be markedly higher than those in the remainder of the deposit.

Seam permeability normally decreases exponentially with depth. In opencut mining, it would be necessary to inject excess water into underlying seams to avoid having the same water flow back into the pit. This implies that high injection pressures would be needed and that low seam permeabilities would only allow limited quantities of water to be lost at each hole.

As an example, deep well injection was considered as a supplementary minewater disposal method for a recent deep pit mine near Singleton. It was proposed that a grid of boreholes between 150 niii and 300 niii diameter be sunk throughout the mine site, and excess water injected under pressure via a series of grouted injection pipes. It was found that to dispose of water excesses under average meteorological conditions, up to 7000 boreholes would have been required. Under more extreme rainfall conditions, the necessary number of boreholes increased dramatically. A feasibility study of the proposal concluded that in view of the large number of holes required and the resulting land area over which the well field would have to be spread, deep well injection was neither physically practical nor financially feasible. In summary, given the geological conditions in the Hunter Valley, it is considered that deep well injection would have little if any application as a means of disposing of excess mine waters.

8.6 EVAPORATION AND IN-PIT BURIAL

Meteorological conditions in the Upper Hunter are such that water disposal by evaporation can be a feasible option. Average annual rainfall is about 650 m, compared with average annual evaporation of about 1600 nih. In addition, most rainfall occurs in the summer months, which coincides with the period of highest potential evaporation. Throughout almost all months of an average year, there is an evaporative gap, or surplus ,of potential evaporation over precipitation. This surplus is usually greatest in December and January, whilst in June, average rainfall approximately equals evaporation.

Evaporation reduces the quantity of waste waters, but is not in itself a disposal method. Concentrated brines or crystalline salt must still be buried or otherwise disposed of in a satisfactory manner. If used as a single control method, the technique can require substantial land areas. A large opencut mine relying only on evaporation ponds may have to devote up to 100 hectares or more of land for ponds and drying beds. This may not be topographically feasible without substantial earthworks and the 46

rehabilitation of these areas after mining would be likely to cause difficul ties.

Where the mining configuration is favourable, it may be possible to locate temporary evaporation ponds in backfill areas without compromising either operational efficiency or low wall stability. The ponds are covered as the low wall advances, effectively reburying any contained salt. Another technique combining both evaporation and in-pit burial can be a particularly flexible water management measure. Advantage is taken of the area of a fully developed opencut to act as an evaporation basin. Water is sprayed onto inactive parts of the pit and permitted to evaporate. Residual salt collected in the mine is then buried as the pit void advances. Spraying can be carried out either with water tankers or fixed jet pipe sprinkler systems.

Site-specific control techniques are sometimes possible which return saline water back to worked out sections of a mine without allowing salt to escape. These include raising the field moisture content of overburden and flooding the worked out goaf areas of underground mines. The latter method is sometimes used in combination with fine rejects disposal from coal preparation plants. It can permit a short term evening out of water surpluses and can enable tailings to be disposed of in an environmentally acceptable way.

Whilst in-pit spraying may have some application as a supplementary water control measure, it would not normally be able to cope with all minewater surpluses. It is relatively labour intensive, and could hinder efficient mining operations. If conducted too close to final surface levels, the success of rehabilitation programmes could be compromised. Finally, it could be argued that it may be less desirable to trap salt on site if long S term pollution controls are made more difficult.

8.7 DESCRIPTION OF DESALINATION PROCESSES

5 8.7.1 Membrane Processes

Reverse Osmosis

Osmosis is a natural phenomenon which takes place when two solutions of S different concentration, for example, brackish minewater and pure water are separated by a semi-permeable membrane. The membrane must reject dissolved salts but, allow pure water to pass through. Because of the dissolved salts, the hydrostatic pressure of the brackish water is less than that of the pure water. The resulting pressure difference, known as the osmotic pressure, forces pure water through the membrane, thus diluting the salt concentration in the brackish water.

However, osmosis is reversible. When a pressure greater than the natural osmotic pressure is applied to the salt solution, the membrane allows water from the salt solution to pass into the pure water while rejecting dissolved impurities. Hence the process is called reverse osmosis.

0 47

The most effective membrane systems in use consist of spirally wound bundles of very stable polyamide hollow fibres encased in a tubular container called a permeator. The selection of this type of system using, in effect, self-supported, heavy-walled membrane pipes (about 50 urn internal diameter), provides a compact module suitable for long-term reliable operation.

In operation, the saline water is pressurised by a pump and introduced to the permeator through a porous distributor tube running the length of the module. Influent saline water flows radially across the outside of the bundle of hollow fibres and under the influence of the pressure, desalted water passes through the fibre walls, down the bore of the fibres to the open ends, from which it is drawn off as purified product. The reject brine flows along the outside of the bundle where it is discharged to waste. In some applications up to 90 per cent of dissolved salts can be extracted from brackish water using hollow-fibre-membrane reverse osmosis.

Because the original hydrostatic pressure difference is directly related to the concentration of dissolved salts, the pressure required to reverse the osmosis is also related to this concentration. Consequently pumping costs depend on the salinity of the influent water. Reverse osmosis is therefore more suited to the desalination of low salinity waters than to concentrated liquors.

Reverse osmosis is a concentrating process. Along the membranes, and in the reject from the modules, the various elements present in the raw water become 2 to 5 times more concentrated. To avoid fouling and precipitation, the raw water must be pre-treated. The extent of this this pre-treatment is dependent on the levels of suspended and undissolved inorganic and organic matter and the existence of undesirable elements or ions. Pre- treatment typically includes addition of chemicals to sequester sealing elements and to modify feedwater pH. The filtering and removal of particles would be necessary for minewater treatment. Post-treatment for example, chlorination, might also be required depending upon the desired end use. Residual concentrated brines remain that have to be disposed of in an environmentally satisfactory manner.

El ectrodialysi s

Electrodialysis is a process using electrical energy for the desalination of brackish waters.

Unike most desalting processes, an electrodialysis plant removes the dissolved salts from the water and not the water from the salts. it therefore uses no heat or high pressure and requires only an electic power supply.

Dissolved, ionised salts in water are either positively or negatively charged, and an electrodialysis unit removes these salts by ion selectively using pairs of cation and anion permeable membranes. A large number of these membrane pairs, separated by spacers to form water compartments, are clamped between electrode plates. When an electric current is applied, salts in the water migrate through membranes having an opposite charge and concentrate at membranes of similar charge. Water in alternate I 34

compartments thus becomes either more diluted or concentrated and leaves the membrane 'stack' via a collector system in two streams; the main stream is desalted water and the other a saline stream which is recycled to minimise wastage of water.

Membrane pairs are produced from a durable synthetic ion exchange material and are stable over wide ranges of temperature and pH. No undue stress is exerted on the membranes as the electrodialysis process is carried out at low pressure and several modules can be used in series without the need for individual pumping.

An electrodialysis plant becomes more economic in operations as the raw water temperature increases. This is due to the fact that the electrical resistance of a solution decreases as its temperature rises.

The potential saving, which is accompanied by a small gain in membrane area, assists the competitive economics of the process.

An electrodialysis unit consists of a raw water strainer, raw water pumping equipment, cation and anion permeable membranes, electrodes, pipework, instruments, etc. Operation is simple and, can be supplied with automatic control s.

The water entering a stack must be free of suspended matter, colloids, iron and organic matter and commonly a pre-treatment plant would be required to ensure the necessary inlet quality. However, modern electrodialysis plants are less sensitive to feedwater composition than reverse osmosis plants and so can tolerate much simpler water pre-treatment schemes. Since groundwaters in many regions of Australia require extensive pre-treatment for reverse osmosis, electrodialysis may be more competitive than some other desalination techniques, particularly for lower salinities (<3,000 rng/L). Electrodialysis is not ipplicable where very pure product water is required, since the amount of electric current required depends on the amount of dissolved salt to be removed and pure water has a very high electrical resistance.

Ion Exchange

Ion exchange can be defined as the reversible interchange of ions between a solid medium and an aqueous solution. To be effective, the ion exchange medium must contain exchangeable ions, be insoluble in water, and have a I porous structure that allows passage of water molecules. Within the solution and the ion exchange medium, a charge balance or electroneutrality must be maintained, i.e., the number of charges, not the number of ions, must remain constant. Ion exchange materials usually possess a preference for multivalent ions, thus they give up monovalent ions. But this reaction can be reversed by increasing the concentration of monovalent ions. This reversal provides a means of regenerating the ion exchange medium once its capacity has been saturated.

The most common example of ion exchange is the softening of mineral-bearing water for domestic purposes. Calcium and magnesium content causes hardness. The ion exchange material is charged with monovalent cations, usually sodium. Hard water is passed through a bed of the material, and

0 49

the divalent cations are exchanged for sodium ions. When more than one type of cation is available, the material will have an affinity for certain ones more than others. This can be an advantage or a detriment, depending on the objective.

Ion-exchange methods have been used for the demineralisation of water for more than three decades. The simplest mode of operation, which is still widely used, involves a unit that consists of series of columns containing a strong acid cation exchanger and strong base anion exchanger. The regeneration of the strong acid and base resins requires large quantities of chemicals, which makes such an arrangement very expensive. Approximately two-thirds of the cost is in chemicals. It is therefore current practice to replace the strong base anion exchanger with a weak base resin, thus reducing sharply the amount of base needed for regeneration. Even in this case, the chemicals used for regeneration represent more than half the cost (ref. 33)..

8.7.2 Phase Change Processes by Distillation

Multistage Flash

In a simple distillation process, saline water is heated to produce vapour which passes over cooling surfaces where it condenses and is collected as pure water. In this process the latent heat released in condensation is lost and the salt concentration in the saline water continually increases until eventually salt is produced. The multi-stage flash distillation process differs in principle from this in several ways, namely:

- the saline water is introduced through tubes and is heated under pressure to boiling point,

- progressive pressure reductions after initial heating allow the water to continue to boil and produce steam,

- the steam condenses on the tubes thus allowing recovery of the latent heat,

- the concentrated brine produced can be recirculated.

Considering the process in more detail, the saline water and recirculating brine are passed through steam tubes in the brine heater (heat input section) where the temperature is raised under pressure. This heated brine then flows into the first flash chamber of the evaporator through an orifice where the brine pressure is reduced. The pressure reduction results in the brine being at a temperature higher than the saturation temperature corresponding to the reduced pressure and it immediately begins to boil. This process is referred to as 'flash evaporation'. The steam so produced is salt free, but the violent agitation caused through 'flashing' results in droplets of salt water being thrown upwards, and the steam is therefore passed through a vapour separator, which intercepts any such droplets and prevents them being carried over into the product tray. The steam, however, contacts the relatively cool tube bundles situated above the produce water tray. It condenses on these tubes and drips into the tray and in the process of condensing it releases its latent heat to the brine within the tubes.

After the first flash, the brine is still hot enough to boil again at a slightly lower pressure. To enable this to be done, the evaporator is divided into a number of chambers each at a pressure lower than its predecessor and the same brine is made to flash successively in each of these chambers, each flash giving a quantity of distillate. After collection in the product trays the product water is then pumped out and chemically treated before being delivered into storage reservoirs. The chemical treatment reduces the corrosiveness of the pure product water.

As it passes through successive chambers the brine is concentrated. On reaching the last chamber the brine is approximately double the concentration of the intake water. To avoid over-concentration which could result in calcium sulphate scaling, part of the concentrated brine is rejected for disposal while the remainder is mixed with incoming saline water and is returned to the evaporator for recirculation.

The evaporator consists of three distinct sections. The first section is referred to as the "heat input section" (or the brine heater). The second, which consists of all but the last two or three chambers is termed the 'heat recovery section". In this the latent heat of the condensing steam is recovered by the recirculating brine, thus requiring only a limited input of heat at the brine heater. The third section, which comprises the last two or three chambers is termed the 'heat rejection section'. In this, cooling water is passed through the tube bundles in the chambers and rejected after absorbing the latent heat of the condensing steam. A part of this 'rejected' hot water is fed into the recirculating brine circuit to make up for the quantities evaporated as distillate and rejected as concentrated brine.

To avoid deposition of calcium carbonate and magnesium hydroxide on the brine heater tubes, the alkalinity in make-up saline water is destroyed chemically by injection of sulphuric acid. The bulk of carbon dioxide released by the resultant chemical reaction is extracted to the atmosphere at a decarbonator. Any residual carbon dioxide and other dissolved gases in the make-up water is removed at the vacuum de-aerator in order to avoid blanketing of the tube bundles by such gases, which would tend to reduce the heat transfer coefficient.

Most of the flash chambers are under vacuum which is maintained by steam ejectors. The pressure difference between adjacent chambers is caused by an orifice provided on the chamber wall.

Multi-stage flash plants consume large quantities of energy particularly in the brine heater, the intake pumps and the brine recirculation pump. In addition, power is required for the brine blowdown pump, the product water pump instrumentation and controls. The main reason for the high power consumption of the intake and recirculation pump is that the plant requires intake flows and recirculation rates that are between 7 and 12 times the 41

product water flow rate (ref. 31).

Substantial energy savings can be achieved by integration with large centralised steam-electric generating stations. In this way steam can be bled from the power station and fed to the brine heater. However, even with this system an additional small power plant would be necessary to offset the energy disadvantages of a single purpose plant.

Vapour Compression

The vapour compression process is mechanically simple, consisting only of a tube nest, a compressor, a heat exchanger and associated pumps, pipes and fittings. The process operates at ambient temperatures and therefore minimises scaling and corrosion problems.

In the process, incoming saline water is pre-treated with a small dose of scale inhibiting additive and passed through a heat exchanger where heat from discharged brine and product streams is recovered.

This heat is generated in the unit itself and is a converted form of the mechanical energy supplied to compress and circulate the fluids. Consequently, no separate heat source is needed.

The saline water is mixed with recirculated brine and sprayed on the outside of a bundle of horizontal heat transfer tubes, at a rate just sufficient to create thin, continuous liquid films.

A centrifugal compressor provides, through its suction, a pressure lower than the equilibrium pressure of the brine. As a result, part of the brine flashes into vapour.

After passing through a demister to remove droplet carry-over, the vapour is compressed and discharged to the inside of the tubes. There it condenses, supplying the latent heat required for the flashing process. The salt-free condensate and the rejected brine are pumped out, after exchanging heat with the feed.

Non-condensable gases are first concentrated in an auxiliary condenser and then exhausted by means of a rotary vacuum pump, which also serves to create the initial vacuum.

The major advantages of vapour compression are that only minor pre- treatment is needed (screening, chlorination, scale control additives), high product purity is achieved, very high concentration ratios can be achieved (useful if effluent disposal is a problem) and a wide range of feed salinities can be tolerated. However, because the power requirements for vapour compensation are independent of salinity, for low salinity waters, reverse osmosis and electodialysis use less power.

Vertical Tube Evaporation

Like the Multi-stage flash process, the vertical tube evaporation process consists of a number of chambers where the pressure is successively 52

reduced. In this process each chamber is referred to as a VTE effect.

Each VTE effect consists of a bundle of vertical fluted tubes with saline waste and recirculated brine flashing on the inside in an up-flow mode and steam condensing on the outside and being collected as distillate. Steam is produced by the flashing brine as the pressure in each effect is successively reduced, and by boiling due to the heat supplied from the condensing steam and flashing distillate. The generated steam passes through a separator and demister to the next effect.

Each effect also contains feedheater tubes in which saline water is progressively heated by a part of the generated steam. The condensed steam is combined with the distillate produced on the vertical tubes.

The brine flows from the top of the vertical tube bundle through a flow channel by gravity to the bottom of the next effect and flashes through orifices located below the vertical tubes. The concentrated brine is removed from the last effect by a blowdown pump.

. The initial heating in the first VTE effect is provided in the form of steam from a boiler plant. After losing its heat in the VTE effect, the steam condensate returns to the boiler for reheating.

8.7.3 Phase Change Processes by Freezing

Desalinating by freezing is based on a crystallisation process. This process demands upon the fact that when saline water freezes, the individual ice crystals consist of pure water and the salt remains (either in brine solution or as solid particles) outside the crystals. If the mass of crystals is porous (i.e., 'slushy', rather than hard solid), it is possible to drain much of the residual brine from the mass, and to wash out most of the remainder with fresh water. The washed ice is then melted, the resulting water containing less than about 550 mg/L of dissolved solids (ref. 38). S Several variations of the basic freeze process have been tested during the past twenty years but only the vacuum freeze vapour compression process has been developed to the point where it is ready for commercial exploitation, if or when market conditions justify the cost. However, there is believed to be no current activity with this process.

In another process, a liquid refrigerant is mixed directly, with saline water. An exchange of heat between the saline water and the refrigerant causes the refrigerant to vaporise and a portion (about half) of the water to freeze; the individual ice crystals remain separated from one another so that they are easily moved, drained and washed. The washed ice is then repulped, using a circulating stream of product water, and is melted in a 'melter-condenser' to become a part of the fresh water stream. In the meantime, the vaporiser refrigerant leaving the crystalliser is compressed so that its temperature is greater than the melting point of pure ice. Most of the compressed vapour condenses in the melter-condenser as it gives up heat to the melting ice. The uncondensed portion of the refrigerant vapour is further compressed so that it can be condensed by giving up its

41 PJ 53

heat streams, exchanging heat with incoming saline water, conserving the S heat necessary to precool the seawater and then warming the effluent streams to environmentally acceptable levels. This process is currently under active study at a pilot plant level.

Still another variation of the freeze process, known as the "absorption freeze vapour compression (AFVC) process", is being examined.

The AFVC process overcomes one of the major problem areas in previous freezing process by using a closed cycle refrigerant loop to power an absorption cycle, thus eliminating compressor problems caused by direct compression of refrigerants contaminated with saline water (ref. 34). The process maintains the low energy advantages of freezing processes but further development is required before it will be available commercially.

Systems utilising volatile water immiscible refrigerants (such as butane) transferring heat by direct contact are also being examined (ref. 32), but as yet are not available.

At the present stage of development freezing processes do not offer practical alternatives.

8.7.4 Relative Economics of Desalination Processes

Most comparisons on the economics or energy requirements of different desalination processes refer to the use of processes for obtaining fresh water for potable purposes from seawater rather than brackish water to meet re-use or discharge criteria. Since the costs of some desalination processes are independent of salinity, and for some the costs decrease with salinity, direct cost comparisons on the basis of seawater desalination require careful interpretation. In many cases direct interpretation is not possible due to the method of data presentation in the literature.

Ammerlaan (ref. 31) carried out an energy consumption comparison of reverse osmosis, vapour compression and multistage flash processes for the desalination of seawater. In all of these processes electrical energy is required to operate the intake pump. In the vapour compression process additional electrical energy is required for the compressor. In the multistage flash process additional energy is required in the form of electricity for the recirculation pump while even larger amounts of energy in the form of steam are required for the brine heater. Ammerlaan found that for each of the three desalination processes considered there existed at least a threefold difference in energy consumption be1ween a best possible case in an ideal situation and a worst case when local conditions were unfavourable. Consequently, the selection of the most appropriate process for a particular case would be site dependent.

Nevertheless, Ammerlaan was able to show that from an energy point of view reverse osmosis used much less energy than vapour compression or multistage flash. The energy consumption data for all three processes are presented below. 54

. TABLE 20

Process Energy Required MJ/m 3

Multistage flash 202 - 399 Vapour compression 220 - 309 Reverse osmosis 65 - 173

* Note 1000 m 3 = 1 ML.

In the case of vapour compression, energy consumption can be reduced by using a direct diesel drive but this is not advised where high availability, high reliability and low maintenance are desired. The favourable conditions for multistage flash which would result in consumption at the lower figures within the range, would include the availability of cheap waste low pressure steam. Since this would be unlikely in the Hunter Valley, energy in the form of steam would need to be converted from other forms and as a result total energy consumption would be within the upper end of the range.

In relation to desalination to brackish water with total dissolved salts at about 5000 mg/L, energy requirements for reverse osmosis would be substantially less than those for seawater, probably about 20 per cent. Further reductions, by about half, could be obtained if energy were to be recovered from the high pressure brine discharge. However there is little operating experience with energy recovery in reverse osmosis systems.

An energy consumption comparison between reverse osmosis and multistage flash was also carried out by Ludwig (ref.37). This comparison covered both seawater and brackish water and in addition, it included the electrodialysis process. For brackish water with 5000 mg/L of salts, the energy consumption data are presented in Table 21.

TABLE 21

Process Energy Required Md/rn 3

Multistage flash 32 - 40 Electrodialysis 9 - 11 Reverse osmosis 7 - 9

The figure of 9 to 11 Md/rn 3 for electrodialysis taken from Ludwig's data, . corresponds well with a figure of 12 Md/rn 3 given by Korngold (ref.36), also for 5000 mg/L brackish water. 55

The two sets of data available from Ludwig and Ammerlaan are not of the same order of magnitude, possibly due to scale effects, and therefore the data cannot be integrated. Nevertheless a relative order of energy consumption can be concluded giving the most efficient energy status to the membrane processes of reverse osmosis and electrodialysis. The energy requirements of the multistage flash and vapour compression distillation processes are substantially higher.

Vertical tube evaporation is another distillation process which suffers from high energy consumption. However a hybrid vertical tube evaporation/vapour compression distillation process can be used with substantial energy savings (ref. 35). Such a hybrid system has a slightly lower energy requirement than reverse osmosis for large capacity seawater I desalination plants. However, the hybrid process would have the same energy even for brackish water and hence for brackish water the membrane processes would still be the more energy efficient.

Although energy is a major cost component of operation, other important operating costs must be taken into account. Reverse osmosis has several I advantages over the distillation processes in operation and maintenance. The low operating temperature of reverse osmosis allows plastics to be used and as a result the water-metal contact area is small. Consequently corrosion and scaling are of much less significance than in distillation processes where these problems are severe. Further, the start-up of distillation processes requires considerable time and care because the control of the process is crucial. By contrast, the reverse osmosis process is operated by a simple on/off switch.

In addition to these cost benefits the reverse osmosis process has other advantages in that in being a segmental system, there is no need to shut down the entire plant for maintenance and cleaning and it is easily expanded by linking in additional segments.

Most of the advantages listed above for reverse osmosis are also applicable to electrodialysis.

In relation to desalination of seawater there is little difference in capital costs of the various processes. This can be concluded by data presented by Glueckstern (ref. 34a).

However for brackish water desalination, the capital costs of the membrane processes were found to be about 20 per cent of those for the distillation processes. Glueckstern also gave a total cost comparison for a 100 ML/day plant for various processes and this is presented below in tabular form in 1979 prices.

In relation to reverse osmosis and electrodialysis there is a requirement for pre-treatment, the required level being dependent upon local conditions. This could have the effect of doubling the capital cost component and adding to the operation and maintenance component. Nevertheless, on the basis of all the foregoing information it is unlikely that local factors would ever favour a distillation process over membrane processes for the desalination of minewaters in the Hunter Valley.

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TABLE 22

Costs %/m 3

Process Capital Operation and Energy Total Mai ntenance (4%'/kWh)

Multistage flash 44 9 26 79 Vertical tube evaporation 44 9 22 75 Reverse osmosis 9 9 11 29 Elecrodialysis 13 6 35 54

Of the two suitable membrane processes, reverse osmosis appears to be the more favourable, particularly for total dissolved salt levels normally encountered in minewaters.

To treat surplus minewater from all the proposed collieries, a single plant of about 11 MLD would be required. This capacity is on the basis that mines could all store surplus water to allow a constant feed rate to the treatment plant. If sufficient capacity was required to treat all discharges from a 1 in 10 wet year, a plant of about 55 MLD would be needed. Once again, this assumes that sufficient storage can be made available to give a constant feed rate.

Whilst a single plant would be the most economical in both capital and operating costs, this would be more than offset by the cost of the pipeline network required to link all mines to a central plant. For the purposes of this study, it has been assumed that small groups of mines could be linked, and that 10 plants will average capacities of 1 to 5 MLD would be considered. Based on 1983 capital cost estimates provided by a water treatment consultant, it appears that each plant would cost between about $2 Million and $3.2 Million. This includes the necessary water pretreatment equipment, but excludes the cost of pipework to link adjacent mines together. Total capital costs would therefore be in the range of $20 to $32 Million, plus pipework, pumping and storage charges. Annual costs for operation and maintenance, chemicals and energy would be around $250,000 per plant, or $2.5 million in total.

Two further considerations are relevant. Firstly, desalination is not a disposal method. Quantities of concentrated brines and treatment sludges would still have to be disposed of in an environmentally satisfactory way near the treatment plants. Secondly, desalination requires extensive water treatment, whether this be simple anti-scaling chemicals or coagulation, softening, filtration and pH correction. Having produced a high quality treated water, it would seem incongruous that the water would then be discharged into a river. However, given the costs of pumping and reticulation, unless a user was located adjacent to the mine, there would be no realistic alternative. 57

In summary, a number of treatment and disposal alternatives have been reviewed in the present section. These include staged discharge, transport by pipeline to suitable receiving waters, deep well injection, evaporation and desalination. On the basis of effectiveness, environmental suitability and cost the most favourable option is staged discharge. TOLERANCE OF IRRIGATLD CROPS TO SAUMTY

SECTION 9

9. TOLERANCE OF IRRIGATED CROPS TO SALINITY

9.1 WATER FOR IRRIGATION

Irrigation may be defined as the application of water to the soil for the purpose of supplying moisture essential for plant growth.

The two main objectives of irrigating are:

i . to increase the yields and quality of agricultural produc- tion,

ii. to maintain levels of production and yield during periods of insufficient rainfall as a form of crop insurance

A crucial element in the success or otherwise of irrigation practices is water quality, with salinity in particular being a major factor limiting crop production. Successful irrigation over a long period requires that the root zone should remain low in salt content and should not become permanently saturated with water.

In order to achieve the first objective, sufficient water must be applied to leach accumulating salts down below the root zone. Care must be taken however to ensure that the natural drainage of groundwater away from the area is adequate to avoid the raising of water tables up into the root zone. If the water table is within or close to the root zone, and the groundwater is saline, the problem is more severe. Salt tends to concentrate in the root zone due to capillary action and evaporation, which can seriously retard plant growth.

9.2 SALINITY EFFECTS ON CROP YIELDS

The presence of excess salts (in the form of carbonate, bicarbonate, sulphate, chloride, calcium,' magnesium, potasiuni and sodium ions) in applied water and soil has the effect of reducing the ability of the soil and water to support plant life. The effects are threefold and depend on the type of plant, on the relative proportions of the dissolved ions, and on soil type.

Firstly, high concentrations of dissolved salts in soil moisture increase the osmotic.pressure of the solution, making it more difficult for a plant to withdraw relatively pure water for its consumption. In addition, it increases the salt content of water in the plant itself, inhibiting growth.

Secondly, specific ions such as sodium, chloride and boron may cause toxicity problems if uptaken or accumualted in excessive amounts. Although tree crops and woody perennials are more sensitive than other species, most plants are affected when concentrations are high.

Thirdly, salts may affect plant growth by modifying the structure and characteristics of the soil. For instance, water with a high sodium

0 59

content relative to calcium and magnesium will, if continuously applied, cause a sodic soil of low permeability to form, thus restricting root growth and increasing the build up of salts.

These three aspects of water salinity are discussed in detail in this section. 11

9.3 IRRIGATED CROPS GROWN ALONG THE HUNTER RIVER

Table 23 indicates the areas of various irrigated crops that are grown along the Hunter River between Glenbawn Dam and Maitland, and the total amount of water diverted for irrigation purposes. Table 24 elaborates on the types of crops included in each group category listed in Table 23.

TABLE 23

AREA AND TYPES OF CROPS IRRIGATED AND TOTAL WATER DIVERTED FOR IRRIGATION FROM THE HUNTER RIVER*

Year Ending

Area of Crops 30/6/80 30/6/81 30/6/82 Average Irrigated ha ha ha % Area (ha)

Summer cereals 555.5 5.5 142.0 1.2 306.0 3.6 334.5 Winter cereals 283.0 2.8 344.0 2.8 63.0 0.7 230.0 0 Summer oil seeds 54.0 0.5 18.0 0.1 0.0 0.0 24.0 Citrus 8.0 0.1 18.5 0.2 13.0 0.2 13.2 Lucerne 4622.5 46.1 6443.0 52.3 5190.5 61.0 5418.7 Summer pasture 2397.5 23.9 2385.0 19.4 1202.5 14.1 1995.0 Winter pasture 867.0 8.6 368.5 3.0 50.0 0.6 428.5 Vegetables 184.0 1.8 276.0 2.2 201.5 2.4 220.5 Vineyards 597.0 5.9 901.0 7.3 902.0 10.6 800.0 . Wheat 40.5 0.4 139.0 1.1 0.0 0.0 59.8 Other 443.5 4.4 1279.0 10.4 576.5 6.8 766.3

Total 10052.5 100.0 12314.0 100.0 8505.0 100.0 10290.5 40

Total Water Diverted ML 69913 95663 31026

0 * Between Glenbawn Dam and Maitland Source: Water Resources Commission (1982)

The figures in Table 23 show that lucerne occupies the largest area of any irrigated crop. Lucerne and pasture grasses together occupy approximately 0

11 7850 ha or 76 per cent of the total area irrigated.

Dairy farms along the Hunter River, which produce approximately 23 per cent of the Stat&s annual milk supply, depend on this lucerne and pasture production to feed their dairyherds either by direct grazing or as conserved fodder in the form of hay.

Vegetable production in the Valley is centred at Singleton and Maitland. Carrots are the main vegetable crop grown at Singleton whilst potatoes, cabbages and onions are grown at Maitland.

TABLE 24

SUB-DIVISION OF CROP CLASSIFICATIONS SPECIFIED IN TABLE 23

Group Category Typical Crops

Cereals Oats, barley, sorghum, millet

Oils Linseed, safflower, rape seed, sunflower

Citrus Oranges, lemons, mandarins, grapefruit S Pasture White clover, rye grass, kikuyu, subterranean clover, phalaris

Vegetables Carrots, lettuce, potatoes, cabbage, cauliflower, onions 1-1

Many of the vineyards in the Upper Hunter are irrigated to ensure regular cropping. Trickle methods are usually preferred to avoid leaf scald.

11

9.4 SALINITY TOLERANCE OF CROPS

In order to place salinity levels of the Hunter River in proper perspective S it is necessary to establish the tolerance levels of relevant crops to salt in irrigation water.

As discussed earlier, the three most important factors are the total soluble salts concentration, the effect of specific ions such as chlorides on tree crops, and the propensity for irrigation waters to disperse clays thus reducing soil permeability.

Dissolved salts are present in water in the form of electrically charged ions and can be measured by the extent to which water conducts electrical current (its electrical conductivity). The greater the electrical conductivity (EC), the greater the amount of salts present.

0 61

For this study, the conductivity is measured in microsiemens per centimetre (pS/cm) at 25°C. An approximation of the total soluble salts (mg/L) can also be obtained by multiplying the conductivity by a conversion factor of 0.65.

The likelihood of irrigation water causing salinity problems to plants can be judged by its EC reading. Water with a conductivity between nil and 700 is/cm is considered to be of relatively low salinity. It can be used for irrigation of most crops on most soils with little probability of salinity damage to the majority of plants. Higher salt levels may be applied to more tolerant crops. Irrigation water can be subdivided into five classes, as shown in Table 25 (ref. ha).

From Table 26 there is a maximum level of salt that plants can tolerate without causing a reduction in yield. As the salt level increases past that point there tends to be a progressive reduction in yield to a point where the crop will not grow. The threshold tolerance level varies between different crops and even different varieties within a species. Plants like beans and strawberries for example are very sensitive to salt whereas barley and beet are quite tolerant.

Crop maturity may also affect the susceptibility of plants to saline water. For instance, during the early seedling stage of barley, irrigation water should not exceed 3000 pS/cm but when established, plants can tolerate 5300 p S/cm without yield loss and will incur a 10 per cent yield loss at 6700 pS/Cm (ref. 11).

The salt tolerance values shown in Table 26 are based on the following criteria:

Irrigation by either furrow, flood or sprinkler method.

An extended drying out period between irrigations (if irrigation water is applied more frequently, for example by trickle microjet, the salt concentration in the soil solution is reduced, hence water with a higher salinity level may be applied).

Fifteen per cent extra water applied above the crop requirement to allow for leaching.

This additional water is necessary to leach salts left in the soil after the crop has consumed its requirement and so maintain an equilibrium. It should also be noted that application of leaching fractions in excess of the leaching requirement effectively reduces the average soil salinity in the root zone. As a result, a crop with a given level of salt tolerance may be irrigated with water of a poorer quality than indicated in Table 26 for any given level of yield reduction by applying a higher leaching fraction.

In areas where rainfall is sufficient, it may not be 62

TABLE 25

GENERAL CRITERIA FOR THE SALINITY OF IRRIGATION WATER

Electrical Total fl Conduc- Soluble tivity Salts (MS/cm) (mg/L)

Class 1 I Low salinity water can be used with most crops on most soils, with all methods of water application, with little likeli- hood that a salinity problem will develop. Some leaching is required but this occurs under normal irrigation practices, except I in soils of extremely low permeability ...... 0-280 0-175

Class 2 Medium salinity water can be used if a moderate amount of leaching occurs. Plants with medium salt tolerance can be I grown, usually without special practices for salinity control. Sprinkler irriga- tion with the more saline waters in this group may cause leaf scorch on salt- sensitive crops, especially at high temperatures in the daytime and with low I water application rates ...... 280-800 175-500

Class 3 High salinity water cannot be used on soils with restricted drainage. Even with adequate drainage, special management for I salinity control may be required, and the salt toleranbe of the plants to be irriga- ted must be considered ...... 800-2300 500-1500

Class 4 Very high salinity water is not suitable S for irrigation under ordinary conditions. For use, soils must be permeable, drainage adequate, water must be applied in excess to provide considerable leaching, and salt- tolerant crops should be selected ...... 2300-5500 1500-3500 n Class 5 Extremely high salinity water may be used only on permeable, well-drained soils under good management, especially in relation to leaching and for salt-tolerant crops, or S for occasional emergency use ...... Above 5500 Above 3500

Source: ref. ha.

S TABLE 26

CROP SALT TOLERANCE

Maximum Electrical Conductivity of Water (EC) in US/CIS xlO

VEGETABLE AND FRUIT CROPS FIELD AND FORAGE CROPS AND PASTURES

Yield oecrease Due to Irrigation Yield Decrease Due to Irrigation Crop Crop No Loss lOs Loss 2Ss Loss No Loss lOs Loss 25% Loss v Beets 2.7 3.4 - Barley 5.3 6.7 8.7 Broccoli 1.9 2.6 - Cotton 3.1 6.4 - E Tomato 1.7 2.3 3.4 Rape 4.9 6.0 - Cucumber 1.7 2.2 - Sugarbeet 4.7 5.8 7.5 G Cantaloupe 1.5 2.4 - F Wheat 4.0 4.9 - Broadbeans 1.1 1.8 - Safflower 3.5 4.1 5.0 E Spinach 1.3 2.2 - I Soybean 3.3 3.7 - Watermelon 1.2 - - Sorghum 2.7 3.4 4.8 T Cabbage 1.2 1.9 - E Peanut 2.1 2.4 - Cauliflower 1.2 1.8 - Rice (paddy) 2.0 2.6 - Potato 1.1 1.7 - L Sesbania 1.5 2.5 - Sweet Corn 1.1 1.7 - Corn (grain) 1.1 1.7 2.5 B Sweet Potato 1.0 1.6 - D Sugarcane 1.1 2.7 - Pepper 1.0 1.5 Flax 1.1 1.7 - L Lettuce 0.9 1.4 2.1 Broadbean 1.1 1.8 - Radish 0.8 1.3 - Cowpea 0.9 1.3 - E Onion 0.8 1.2 - Beans (field) 0.7 1.0 - Carrot 0.7 1.2 1.9 S Beans 0.7 1.0 1.5 Tall wheat grass 1.0 6.6 9.0 Fig, Olive 1.8 2.6 - Wheat grass (fairway) 5.0 6.0 - Pomegranate 1.8 2.6 - Couch grass 4.6 5.7 6.3 Grapefruit 1.2 1.6 - Barley (hay) . 4.0 4.9 6.3 5.9 Orange 1.1 1.6 2.2 Perennial ryegrass 3.7 4.6 Trefoil, birdsfoot, 4.0 Lemon 1.1 1.6 - 3.3 - narrow leaf Apple 1.0 1.6 - Phalaris 3.9 Pear 1.1 1.7 F 3.1 - F Tall fescue 2.6 Prune 1.1 1.7 - 3.9 - 0 Crested Wh. grass 2.3 4.0 - R Walnut 1.1 1.6 - Peach 1.1 1.4 - Vetch 2.0 2.6 - Il Sudan grass 1.9 3.4 Apricot 1.1 1.3 - - o Wild rye, beardless 1.8 2.9 Grape (Vitus spp) 1.0 1.7 2.7 - Trefoil, big 1.5 1.9 (Thompson app) 1.8 2.7 A - Lucerne 1.3 2.2 3.6 Almond 1.0 1.4 - 2.1 Plum 1.0 1.4 - O Lovegrass 1.3 - T 1.2 2.1 Blackberry 1.0 1.3 - Corn (forage) - Boysenberry 1.0 1.3 - E Bent grass, Brome grass, - - - Canary grass, Rhode grass Avocado 0.9 1.2 - Clover, strawberry 1.6 2.4 Raspberry 0.7 1.0 - 1.0 Cocksfoot 2.1 Strawberry 0.7 0.9 1.2 1.0 - Meadow Foxtail 1.7 Passionfruit 0.7 0.9 - 1.0 - Millet - - - Clover, alsike, ladino - - - Adapted from Ayers (7977) and Ayers and Westcot (7976) by V.S.W. eparnent of Agr(oulare (:282) (ref.11). ME

necessary to add extra irrigation water to achieve adequate leaching especially when falls occur during non-crop periods.

Increases of 10 to 20 per cent above the indicated salt tolerance value may have little effect if accompanied by favourable weather conditions, good irrigation management and efficient, well maintained irrigation equipment.

9.5 CHLORIDE TOXICITY S

Foliar adsorption of toxic levels of chloride ions tends to result in leaf burn followed by excessive leaf drop restricting production and even causing death to more sensitive plants. At less obviously damaging concentrations, effects have been demonstrated on photosynthesis and S transpiration rate (ref. 11).

In general terms, trees, shrubs, vines, woody crops and ornamentals are particularly sensitive to chloride whilst annual crops tend to be more tolerant.

S The maximum levels of chloride in irrigation water are shown in Table 27. Waters with a chloride level of 70 mg/L are satisfactory for spray or overhead irrigation of all crops grown along the Hunter River. Waters with a level exceeding 250 mg/L should not be used for spray irrigation of any of the crops listed in Table 27. C As can be seen from Table 27, crops are more tolerant to chloride when water is applied to the soil rather than if water is sprayed on the leaves.

•

S

S

C Ll

TABLE 27 10 MAXIMUM LEVELS OF CHLORIDE IN IRRIGATION WATER

Crop (variety/rootstock) Chloride Concentration mg/L fl

(a) SURFACE IRRIGATION METHODS * Citrus: Pond rus. tn fol i ata 120 Rough lemon 200 C Troyer citrange, Sweet orange 300 Rangpur lime, Cleopat'a mandarin 600

Stone Fruits: Plum - Marianna 600 - Myrobolan 370 Plum, peach, apricot and almond seedlings 235 Avocado - Mexican 120 - West Indian 190

Grape: Ramsey, 1613-3 950 Dog Ridge 700 Sultana 600 Cardinal 235

Soft Fruit: Blackberry, boysenberry 235 0 Raspberry 120 Strawberry 120 - 190

(b) OVERHEAD SPRINKLERS Citrus 100 Stone Fruits 70 Grapes 150

* References: Bernstein (1967) Grieve & Walker (unpublished data) ** References: Jones (1972) Till (1975) Assuming daytime application; limits may be increased by 50 per cent or more for irrigation at night or under cool conditions. Overhead irrigation is not recommended when water contains more than 250 mg/L chloride.

Source: Department of Agriculture (1982) (ref.11).

40 9.6 SODIUM HAZARD

Low rates of water infiltration into soil may arise from changes in soil chemistry caused by irrigation water quality. High sodium levels in irrigation water relative to calcium and magnesium may lead to an exchange of sodium for divalent cations on clay crystals. The resultant increase in exchangeable sodium can cause dispersion of clay particles and sealing of the soil surface when leached by rainfall.

The propensity for irrigation waters to disperse clays is evaluated by the sodium absorption ratio (SAR) of the applied water. The sodium absorption ratio is calculated by the equation:-

(Na ) S.A.R. =

2 ((Ca 2+) + (Mg2Y

2) where (Na + ) is the concentration of sodium in rneq/L (Ca2+) is the concentration of calcium in meq/L and (Mg2+) is the concentration of magnesium in nieq/L.

This ratio may have to be modified by a correction factor when irrigation waters contain high levels of carbonate and bicarbonate.

Problems caused by high adjusted SAR levels include poor internal drainage (waterlogging) brought about by low subsoil permeability and sodium toxicity to plants through root absorption. 0 As is shown in Table 28, if the adjusted SAR is less than 6.0 (mmole/L)½ waterlogging of the soil is unlikely. Levels between 6.0 and 9.0 may pose a problem but it can usually be alleviated by the addition of gypsum to the water or to the soil.

S SAR levels in excess of 9.0 which are likely to create severe problems may be mitigated by the application of up to 20 tonnes of gypsum per hectare.

The frequenôy of gypsum application will vary according to the soil type and quantity of water supplied.

Trees, shrubs and woody ornamentals are more likely to be adversely affected by sodium than annual species. Sensitive plants should not be irrigated with water having an adjusted SAR value above 3 (mmole/L)½ . without considering the application of gypsum to the water.

0 67

TABLE 28

SODIUM, CALCIUM AND MAGNESIUM RELATIONSHIP (as determined by adjusted SAR:unit of measurement [ninole/L]½)

Degree of Problem

None Increasing Severe

Poor internal drainage <6 6to9 >9 Toxicity of Na ions to sensitive crops by root absorption <3 3to9 >9

Source: Ayers & Westcot (1976) as quoted in ref. 11. Note: Adjusted SAR is corrected for alkalinity (ref. 11)

9.7 ECONOMIC VALUE OF AGRICULTURAL OUTPUT

As the salinity of irrigation waters increases, losses are experienced in agricultural output. To gain an approximate understanding of the economic costs associated with increased salinity, information was gathered on the value of agricultural output in the Hunter. It is recognised that costs are also incurred by urban centres and industries through scaling of boilers, increased corrosion and heavier uses of soaps (ref. 24). However the heaviest cost per individual can fall on agricultural producers.

Specific information on value of output per crop type per unit area of irrigated land in the Upper Hunter is not easily obtained. Table 29 gives an approximate breakdown based on data supplied by the Australian Bureau of Statistics and the Department of Agriculture.

Data on average area per crop type was aggregated from Table 24. This indicated that gross value of crops from 10,300 ha of irrigated land was about $10.74 Million in 1980-81. Applying the yield decrement data from is Table 26, approximate dollar values could be assigned to various salinity levels in the Hunter. This is summarised in Table 30.

40

10 68

TABLE 29

VALUE OF AGRICULTURAL CROPS (s/ha)

Source Cereal/Hay Lucerne/Hay Vegetables Grapes Wheat

ABS (1980_81)* 1264 811 4086 # 1474 56

Dept. of Agri- culture (1982)** n/a 885 3298 ## n/a n/a S L_ Notes: * Includes irrigated nd non-irrigated production for Maitland, Singleton, Muswellbrook and Scone LGA's (Gross Value) ** Irrigated crops only for Hunter Valley as a whole (Gross Margins) # All vegetables S ## Average for cauliflowers, cabbages, carrots, potatoes and lettuce only.

TABLE 30

LOSSES IN CROP VALUE WITH INCREASED SALINITY

Conductivity of Gross Value Loss Percentage Irrigation Water $ Million $ Million Loss S/cm)

>900 10.74 - - 1000 10.72 0.02 0.19 1200 10.64 0.10 0.93 1400 10.48 0.26 2.42 1600 10.24 0.50 4.65 1800 9.95 0.79 7.35 2000 9.70 1.04 9.68 S

Table 30 is based on five major crop types, namely cereal/hay, lucerne/hay, wheat, vegetables and grapes. All varieties of crop within each crop type were for simplicity assumed to have the same salinity response. The most generally sensitive crop type was vegetables, accounting for about 10 per cent of total crop value, or 5 per cent of total agricultural output including dairying. Lettuce was adopted as a typical vegetable for calculating salinity yield losses. .M

The losses quoted in Table 30 assume that there is no conversion to more salt resistant crop types.

If reductions occur in crop output, secondary losses would be expected in dairy output. For purposes of the present analysis, it has been assumed that a given percentage decrease in lucerne production would be associated with a corresponding percentage decrease in dairy output for that portion of the industry dependent on irrigation. The Dairy Industry Marketing Authority in 1981 published a survey of suppliers to the Hexham, Singleton and Muswellbrook milk processing factories. The survey established the average total size of dairy holdings, and the average area of irrigated pastures within those holdings. These figures are summarised in Table 31.

TABLE 31

SIZES OF DAIRY FARMS SUPPLYING REGIONAL MILK FACTORIES (ha)

Factory Average Total Area Average Irrigated Area

Hexham 145 14 Muswellbrook 143 40 Singleton 197 36

The survey also found that the average herd size was 90 cattle. These data confirm verbal advice received from the Department of Agriculture that average irrigated area per dairy holding in the Valley is 30 ha, and that a reasonable stocking rate is one and a half beasts per hectare. That is, for an average herd size of 90, 45 animals or 50 per cent of the total are dependent on irrigation. It would therefore seem reasonable to assign 50 per cent of the total value of dairy output in the Valley to irrigated pastures.

Information on gross value of dairy production is collected by the Australian Bureau of Statistics. Values over three years for the four local govrnment areas of the Upper Hunter are given in Table 32.

From the table, about $10.5 Million in 1980/81 prices could be attributed to dairy output from irrigated pastures. The total value of output from irrigated dairying, crops and pastures would therefore be about $21.24 Million at 1980/81 prices. Applying the yield decrement data from Table 26 with lucerne as the indicator crop for dairying, losses in total output with varying salinity levels are presented in Table 33. 70

TABLE 32

GROSS VALUE OF DAIRY PRODUCTION

($.000)

1978/79 1979/80 1980/81

Maitland 2742 2446 2885 Singleton 6340 6828 8171 Muswellbrook 5470 5698 6514 Scone 3147 3298 3512

Total for 4 LGA's 17699 18270 21082

Source: Australian Bureau of Statistics

TABLE 33

LOSSES IN TOTAL AGRICULTURAL OUTPUT WITH INCREASED SALINITY

Conductivity of Gross Value Loss Percentage Irrigation Water $ Million $ Million Loss (uS/cm)

>900 21.24 - - 1000 21.22 0.02 0.09 1200 21.14 0.10 0.47 1400 20.86 0.38 1.79 1600 20.40 0.84 3.95 1800 19.87 1.37 6.45 2000 19.39 1.85 8.71

There would be additional local and regional losses due to indirect and induced employment in service industries and downstream processors. However it would be beyond the scope of the present study to embark on a comprehensive economic study of these factors.

9.8 CONCLUSIONS

Salinity effects on irrigated crop yields arise from a range of specific 71

problems including osmotic effects on water uptake, toxicity of certain elements and soil permeability.

Of the crops irrigated by water drawn from the Hunter River, lucerne together with various pasture grasses and forage crops predominate, occupying some 76 per cent of the total irrigated area between Glenbawn Dam and Maitland. Figures in Table 26 indicate that lucerne can tolerate a salt level of up to 1300 pS/cm without causing any reduction in yield. Salt concentrations of up to 4000 to 5000 pS/cm are acceptable to most pasture grasses and forage crops without affecting yield.

Toxicity due to the adsorption of the chloride ion is reflected principally in leaf burning. Waters with a chloride level of 70 to 100 mg/L are satisfactory for spray or overhead irrigation of most crops grown along the Hunter River. Concentrations up to 900 mg/L may be tolerated by some crops providing the water is applied to the soil rather than sprayed onto the leaves.

Soil permeability problems can be caused by the dispersive effect on soil structure of high sodium levels.

Adjusted SAR readings of less than 6.0 (mmole/L)½ reflect a satisfactory subsoil permeability and sodium concentration. The application of water with an adjusted SAR level of between 6 and 9 (mmole/L)½ may adversely affect some crops, trees and shrubs although this problem can be somewhat alleviated by the application of gypsum.

Irrigation management practices can significantly reduce the adverse effects of poor water quality. More efficient irrigation systems, higher frequency of irrigation, improved drainage, appropriate soil management practices and better irrigation scheduling can all contribute to maintaining optimum crop yields using poor quality irrigation water.

An approximate analysis of economic losses suffered by irrigation farmers was carried out. It showed that for significant increases in river salinity minor losses occur in annual value of output. FNDNGS AND CONCLUSONS 72

10. FINDINGS AND CONCLUSIONS

The present study examined existing hydrologic and salt cycles within the Hunter River and modelled the consequences of a significant growth in coal mining in the Upper Hunter. A number of findings and conclusions evolved throughout the course of the study. These are summarised below:

One of the main findings was that river salinity is predominantly determined by geology. On the basis of available data, there is insufficient evidence to support a theory that the Hunter is becoming more saline. Whilst certain land uses involving the clearing of native vegetation could conceivably increase salt levels, recent high river concentrations can be adequately accounted for by drought.

S The Hunter, like all rivers, drains saline minerals to the ocean. The minerals are derived from the natural leaching of rocks and soils. Prior to European settlement it would have carried a significant salt load, and this is true to the present day. At Singleton, the river carries an average of about 794 tonnes of salt per day, or approximately 290,000 tonnes per year.

Flows in the river are highly variable. Annual discharges can vary between 1000 per cent and 3 per cent of long term averages. S Instantaneous flows at Singleton have ranged from 12,500 cubic metres per second to zero.

There is a big variation in the quality of both surface and groundwaters in different parts of the Valley. These variations S are attributable to the five major geological sequences that occur throughout the catchment (see Section 2.2).

There is a general trend towards decreasing salinity with increased flows in the river. There is considerable scatter in individual conductivity readings, but the trend is still well defined. Salt loads carried by the river are strongly dependent on flow rate. The majority of salt is carried during the highest ten per cent of discharges.

1 6. Major salt loads usually come from large tributaries with reasonable quality water. Of the 794 tonnes of salt per day passing Singleton, about 39 per cent enters upstream of Denman and about 31 per cent comes from the Goulburn River. The remainder enters between the confluence of the Hunter and Goulburn Rivers and Singleton. In this latter reach, Glennies Creek, Wollombi Brook and Saltwater Creek contribute the most

0 L.A 73

salt.

Although not highly accurate, the modelling procedure developed in the present study gives an approximate indication of direct groundwater accession rates. Groundwater accession to the main stream is not large, though the salt load added is quantifiable. S This would especially be the case in low flow conditions.

The quantity of makeup water required for mines over the next decade is a function of water use policy and the volume that can be harvested from on-site sources. The latter is a function of S catchment configuration and the suitability of sites for the establishment of major st&rages. A meaningful value can only be based on a detailed mine by mine evaluation.

Requirements for the discharge of minewaters are strongly dependent on weather conditions. During a 1 in 10 year dry period, it would be unusual for an opencut mine with a coal preparation plant to need to discharge minewater. Under average conditions most minewater can be used on site depending on the magnitude of in-pit consumption, sizes of minewater storages, etc. For purposes of examining possible effects on the Hunter River and its tributaries, an average discharge of 40 litres per run-of-mine tonne of coal has been adopted. Under 1 in 10 year wet periods, 200 litres per ROM tonne was used.

A suite of computer based models examined the effects of simultaneous discharge from all nines predicted in the next decade under both average and 1 in 10 year wet weather conditions. They indicate that except for very low flows (that is, flows that are exceeded more than about 90 per cent of the time), the main stream of the Hunter River is relatively insensitive to minewater discharges. This implies that provided discharges are avoided for the driest one to two months per year, there will not be substantial changes in river salinity.. Some tributaries are more sensitive, so that controls on mines in certain parts of the Valley should be more rigorous than in others. However in all cases, if discharges are confined to high flow conditions, changes in salinity levels can be kept relatively small.

A number of minewater treatment and control systems are reviewed. There would appear to be little scope for groundwater injection or aquifer recharge as significant control mechanisms. A pipeline to below Maitland would seem to be prohibitively expensive, and would fairly ineffectively duplicate the drainage function of the river. Of the various desalination technologies, reverse osmosis offers the most economical technique for removing salt from minewater. However, except where there is a particular need for the product water, it would

0 74

not present an economically viable means of disposing of most of the pit water in the Valley. On-site management including excess in-pit spraying, overburden infiltration and evaporation offer considerable flexibility, but are not without a major cost penalty and are probably most effective when only used as part of a water management programme. The most promising technique in terms of effectiveness, flexibility, environmental acceptability and economy is controlled stage discharge. To be operated satisfactorily, adequate co-ordination is required betweenminers and other water users. This could probably best be achieved by the integration of river recording, storage regulation, demand controls and discharge limitations. The most appropriate existing body to perform this task would appear to be the Water Resources Commission.

If water quality is to be protected throughout the entire river basin, sufficient attention should be paid to all water users. The present consumption for irrigation is about 74,000 ML per year (ref. 28). If U.S.A. figures for return water apply to the Hunter, about 18,500 ML of irrigation drainage water is returned to the Hunter each year. The concentration of this water would be expected to be similar to pit water, since apart from a small quantity retained by plants, virtually all salt in the original abstracted water would be dissolved in the return water. This shoul d be compared with regul ated mine discharges. With a figure of 40 litres per RUM tonne, mining would discharge about 3,700 ML per year in 10 years time. This is one fifth of that contributed at present by irrigation.

Certain crops are sensitive to irrigated water quality, and the application of saline water can lead to yield losses. Beyond a given salinity concentration which varies from crop to crop, it is not possible to successfully grow these species at all. To quantify the agricultural implications of increased river salinity, yield decrement data were applied to existing crop output from the Valley. The consequential losses to dairying were also included. The analysis showed that for significant increases in mainstream salinity only minor losses of value in agricultural output would occur. The necessary increases in salinity to incur significant losses were substantial, and far beyond the values predicted by the discharge of all future mines into the river. REFERENCES

Ll 75

S REFERENCES

Australian Groundwater Consultants Pty. Ltd. (1983). "Groundwater in the Hunter Valley." N.S.W. Coal Association (in S preparation).

Awad, A.S. (1982). "Regional Water Testing Service - Methods and Interpretation." N.S.W. Department of Agriculture, Biolog- ical and Chemical Research Institute, Rydalmere. S 3. Bernstein, L. (1967). "Quantitative Assessment of Irrigation Water." Amer. Soc. Testing and Materials. Spec. Tech. Pubi. 416, 51-65.

Clampett, W.S. (1976). "Irrigation Farm Management" in "Drought" - Australian UNESCO Seminar 1982. T. Chapman (Ed.). Aust. Govt. Publishing Service.

Day, D.G. (1982). "Hydrogeomorphic Effects of Coal Mining, Hunter Valley, N.S.W." The Australian National University, Centre for Resource and Environmental Studies, Paper 4.

I 6. deKantzow, D. (1981). "The Demise of Irrigation" in "When Will the Hunter Dry Up? - Water Availability and Salinity Problems." The Australian Institute of Agricultural Science, R. Parkin, (Ed.).

Department of Industrial Development and Decentralisation (1981). S "Development Projects in New South Wales, Australia." Department of Industrial Development & Decentralisation, Sydney.

Frith, J.J. & Sawer, G. (Ed.), (1974). "The Murray Waters - Man, Nature and a River System." Proceedings of a Symposium S organised by the Australian Academy of Science et al, Angus & Robertson, Sydney.

Garman, D.E.J. & Muir, G.L. "Water Quality in the Hunter River Valley - The Impact of Natural Processes and the Likely Influence of Future Industrial Development of Water Resources." Water Resources Commission (unpublished).

Geary,, P.M. (1981). "Sediments and Solutes in a Representative Basin." Australian Water Resources Council, Australian Representative Basins Program Report No. 3, AGPS.

Grieve, A.M. (1981). "Effects of Salinity on Irrigated Agriculture" in "When Will the Hunter Dry Up? - Water Availability and Salinity Problems." The Australian Institute of Agricul- tural Science, R. Parkin (Ed.).

ha. Hart, B.T. (1974). " A Compilation of Australian Water Quality Criteria." Australian Water Resources Council Technical

I 76

Paper No. 7.

Hunter Valley Research Foundation (1983). "Investment Projects in the Hunter Region." HVRF, Maryville, N.S.W.

Jacobsen, T. & Adams, R.M. (1958). "Salt and Silt in Ancient Mesopotamian Agriculture." Science, 128.

Joint Coal Board (1982). "Black Coal in Australia, 1981-82. A Statistical Year Board." JCB.

Jones, L.D. (1972). "Sprinkler Irrigation in Sunraysia." Aqua, July 8-10. I

Levy, C. (1983). "Salt ofthe Earth." State Trends, State Bank, Vol. 1, No. 4.

Maunsell & Partners (1979). "Murray Valley Salinity and Drainage Report."

McMahon, T.A. (1976). "Stream Flow Characteristics" in "Drought" - Australian UNESCO Seminar 1972. T. Chapman (Ed.). Aust. Govt. Publishing Service.

Muir, G.L. (Undated). "Investigation of Water Quality in the Hunter I Valley" (draft). Water Resources Commission.

N.S.W. Planning & Environment Commission (1977). "Hunter Regional Plan - Working Paper No. 5, Primary Industry."

------"Hunter Regional Plan - Working Paper No. 8, Coal Resources."

------"Hunter Regional Plan - Working Paper No. 12, Land Use and Settlement."

Perkins, F. (1982). "An Economic Overview of Coal-based Developments in the Upper Hunter." The Australian National University, Centre for Resource and Environmental Studies, Paper 1.

Pillsbury, A.F. (1981). "The Salinity of Rivers." Scientific American, July 1981.

Shepherd, K.H. (1976). "Water Quality Control at the Valley or Regional Level" in "Drought" - Australian UNESCO Seminar 1972. T. Chapman (Ed.), Aust. Govt. Publishing Service.

Tichon, M. (Ed.) (1981). "The Hunter in Perspective - The Impact of Mining and Industry on Agriculture in the Hunter Valley." Seminar Proceedings. Aust. Institute of Agricultural Science.

Till, M.R. (1975). "Salinity in the Mallee Zone of the Murray Valley." Progress Report, April 1975. Horticultural Salinity Sub-committee of the Horticultural Committee of

0

S 77

Standing Committee on Agriculture, Australia.

Water Resources Commission (1982). "Hunter Region - Water Requirements and Storage Proposals 1982 Review."

------(1969). "Water Resources of the Upper 5 Hunter Valley." Survey of Thirty-two N.S.W. River Valleys. Report No. 15.

------(1976). "Water Resources Inventory."

5 DESALINATION REFERENCES:

Ammerlaan, A.C.F. - Desalination 40 (1982). "Seawater Desalting Energy Requirements as a Function of Various Local Conditions."

Brash, R.A. - Desalination 40 (1982). "Trends in the Application of Solar Energy to Water Desalination."

Egozy, Y. & Korngold, E. - Desalination 40 (1982). "Effect of the Energy Crisis on Water Desalination and Waste Water Recycling by Ion Exchange." I Fraser, J.H. - Desalination 33 (1980). "Absorption Freezing Vapour Compression - Process Selection, Pilot Plant Design, Process Economics.

34a. Glueckstern, P. - Desalination 40 (1982). "Comparative Energy S Requirments and Economics of Desalting Processes Based on Current and Advanced Technology."

Kamal, I., et al - Desalination 33 (1980). "RU, MSF and VTE/VC Desalination: A Comparative Evaluation."

5 36. Korngold, E. - Desalination 40 (1982). "Electrodialysis Unit: Optimization and Calculation of Energy Requirements."

Ludwig, H. - Desalination 36 (1981). "Reverse Osmosis in the Desalination of Brackish Water and Sea Water."

Shroeder, P.J. - Desalination 33 (1980). "Freezing Processes - The Standard of The Future - an Update."

S

S

S

.

S

APPENDIX 1 N.S.W. COAL ASSOCIATION QUESTIONNAIRE OF COLLIERIES IN THE UPPER HUNTER REGION - 1] SURVEY SHEET AND INSTRUCTIONS,

S

S

0 N.S.W. COMBINED COLLIE9Y ASSOCIATION - SALINITY SUI1VEY Lme of Collier

No. Item 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

1 RUM output Mt/a

2 Washed coal output Mt/a

3 Capacity of washery t/h

4 Washery makeup requirements L/t RUM coal

5 Groundwater make ML/d

6 Salinity of groundwater mg/L

7 sCapacity of mine water dam(s) ML

8 ECapacity of surface water Uars(s) ML R.

9 Plan area of pit exposed ha

10 Plan area of surface facilities ha

Plan area of out-of-pit overburden emplacements ha

Plan area of rehabilitated 12 mined-out areas ha

13 Unmined area ha

Area of out-of-pit haul roads (unsealed) h a

15 Area watered in-pit ha

Surface (not plan) 16 area of coal stockpiles ha _T T-F 17 I1axirnrn tolerable salinity in washery circuit m g/L 79 .

SALINiTY SURVEY

EXPLANATORY NOTES

item No. Explanation

Anticipated raw coal output in each year.

If no washery on site, place N/A in each box for those years that this applies.

Volume of groundwater to be pumped from pit (opencut) or shafts (underground).

Weighted average (if possible) of salinities in each seam. Ignore dilution by in-pit rainfall. If conductivities only are measured, estimate from salinity (mg/L) = 0.65 conduct- ivity (pS/cm)

7 and 8. These are total capacities of mine and surface water dams, respectively.

9. To include complete area of surface facilities (coal handling and preparation, car parking, truck washdown, fuel and lube, roads, grassed or paved areas, etc.)

Surface area of all raw and product stockpiles at maximum capacity. Ignore covered areas and bins.

This item included to gain company's attitude to use of groundwater in washery circuit. If unable to specify tolerable salinity, qualitative response will suffice (e.g., 'unconcerned' or 'opposedto introduction of additional salinity').

0 .

0 APPENDIX_2 : SAMPLE OUTPUT FROM SALINITY MODEL S S S

TABLE A2. 1

TRIBUTARY DISCHARGES (ML/d) AVERAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 1554 253 92 62 40 28 18 13 6 2 Glenbawn 2121 530 384 298 220 166 116 74 36 11 Rouchel Brook 1100 144 78 44 32 22 14 6 2 - Dart Brook 800 121 57 15 5 2 1 - - - Muswellbrook 6440 1367 784 567 450 358 269 202 120 45 Hunter upstream Goulburn 6558 1395 798 578 458 365 274 206 122 46 Goulburn upstream Sandy Hollow 3998 381 201 122 84 57 33 15 2 - Wybong Creek 859 108 73 50 37 25 20 12 7 3 Goulburn upstream Hunter 4857 489 273 172 120 82 52 26 9 3 Martindale Creek 576 46 25 14 7 3 - - - - NO Saddlers Creek 135 6 4 2 2 1 - - - - Doyles Creek 277 16 7 4 2 1 - - - - Saltwater Creek 98 4 2 1 ------Bayswater Creek 118 28 24 21 18 15 11 8 5 2 Bowmans Creek 205 65 29 13 9 2 - - - Glennies Creek 1682 238 119 76 49 28 19 4 - - Wollombi Brook 2351 301 148 96 60 41 24 13 2 - Loders Creek 122 5 2 2 1 1 - - - - Singleton 17722 2835 1408 898 561 347 221 141 90 57 Mudies Creek 577 7 3 2 1 1 1 - - - JumpUpCreek 361 2 1 1 ------Glendon Brook 405 91 38 21 13 6 5 2 - - TRIBUTARY SALINITIES (mg/L) AVERAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 16 25 35 45 55 65 75 85 95

Pages River 263 609 563 480 490 221 404 669 686 834 Glenbawn 200 235 235 175 225 242 223 264 295 293 Rouchel Brook 273 333 270 325 429 292 311 258 315 364 Dart Brook 269 381 349 558 744 1252 1416 1269 1281 1307 Muswellbrook 274 347 291 264 289 271 292 315 336 407 Hunter upstream Goulburn 275 346 290 265 289 271 292 315 356 406 Goulburn upstream Sandy Hollow 306 565 564 608 616 683 668 677 795 795 Wybong Creek 607 456 507 768 748 813 814 822 1089 1030 Goulburn upstream Hunter 359 540 549 651 667 720 731 769 1111 1000 Martindale Creek 173 201 332 356 432 508 1308 1308 1308 1308 Saddlers Creek 903 2386 3868 3683 3991 4298 4541 4879 4879 4879 Doyles Creek 157 237 264 404 400 434 442 497 788 1052 Saltwater Creek 3900 4506 5111 4826 4540 5244 3871 6825 6825 6825 Bayswater Creek 1030 1006 981 957 1040 1124 1207 1290 3300 3637 Bowmans Creek 144 529 797 744 768 1271 1885 1885 1885 1885 Glennies Creek 129 247: 369 310 341 327 471 555 621 621 Wollombi Brook 157 237 264 404 400 434 442 497 788 1052 Loders Creek 220 518 609 574 641 595 766 730 826 842 Singleton 266 432 540 580 480 523 530 502 546 611 Mudies Creek 220 518 609 574 641 595 766 730 826 842 Jump Up Creek 220 518 609 574 641 595 766 730 826 842 Glendon Brook 220 518 609 574 641 595 766 730 826 842

0 TABLE A2.3

TRIBUTARY DAILY SALT LOADS (tonnes/day) AVERAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 409 154 52 30 20 6 7 9 4 2 Glenbawn 424 125 90 52 49 40 26 20 11 3 Rouchel Brook 300 48 21 14 14 6 4 2 - - Dart Brook 215 46 20 8 4 2 1 - - - Muswellbrook 1766 474 228 150 130 97 78 64 43 19 Hunter upstream Goulburn 1803 483 232 153 133 99 80 65 43 19 Goulburn upstream Sandy Hollow 1223 215 113 74 52 39 22 10 2 - Wybong Creek 521 49 37 38 28 20 16 10 8 3 Goulburn upstream Hunter 1744 264 150 112 80 59 38 20 10 3 Martindale Creek 100 9 8 5 3 2 - - - - Co Ni Saddlers Creek 122 14 15 7 8 4 - - - Doyles Creek 43 4 2 2 1 - - - - Saltwater Creek 382 18 10 5 - - - Bayswater Creek 122 28 24 20 19 17 13 10 16 7 Bowmans Creek 30 34 23 10 7 3 - - - - Glennies Creek 217 59 44 24 17 9 9 2 - - Wollombi Brook 369 71 39 38 24 18 11 6 2 - Loders Creek 27 3 1 1 1 1 - - - - Singleton 4714 1225 760 521 269 182 117 71 49 35 Mudies Creek 127 4 2 1 1 1 1 - - - JuinpUpCreek 79 1 1 1 ------Glendon Brook 89 47 23 12 8 4 4 2 - TABLE A2.4

MAINSTREAM DISCHARGES (ML/day) AVEPAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 4775 927 554 404 292 216 148 93 44 13 Glenbawn 2121 530 384 298 220 166 116 74 36 11 Rouchel Brook 3221 674 462 342 252 188 130 80 38 11 Dart Brook 5575 1048 611 419 297 218 149 93 44 13 Muswellbrook 6440 1367 784 567 450 358 269 202 120 45 Hunter upstream Goulburn 6558 1395 798 578 458 365 274 206 122 46 Goulburn upstream Sandy Hollow 3998 381 201 122 84 57 33 15 2 - Wybong Creek 4857 489 273 172 120 82 52 26 9 3 Goulburn upstream Hunter 11415 1884 1071 750 578 457 326 232 131 49 Martindale Creek 11991 1930 1096 736 585 460 326 232 131 49 Saddlers Creek 12126 1936 1100 766 587 461 326 232 131 49 Doyles Creek 12403 1952 1107 770 589 462 326 232 131 49 Saltwater Creek 12501 1956 1109 771 589 462 326 232 131 49 Bayswater Creek 12619 1984 1133 792 607 477 337 240 136 51 Bowmans Creek 12824 2049 1162 805 616 479 337 240 136 51 Glennies Creek 14506 2287 1281 881 665 507 356 244 136 51 Wollombi Brook 16857 2588 1429 977 725 548 380 257 138 51 Loders Creek 16979 2593 1431 979 726 549 380 257 138 51 Singleton ------Mudies Creek 17556 2600 1434 981 727 550 381 257 138 51 Jump Up Creek 17917 2602 1435 982 727 550 381 257 138 51 Glendon Brook 18322 2693 1473 1003 740 556 386 259 138 51

0 0 40 0 0 0 0 0 0 0 . . 0 S S S S • S

TABLE A2.5

MAINSTREAM SALINITIES (mg/L) AVERAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 270 353 294 238 284 241 250 333 341 308 Glenbawn 200 236 234 174 223 241 224 270 306 273 RoucIe1 Brook 225 257 240 193 250 245 231 275 289 273 Dart Brook 270 356 300 248 293 248 255 355 341 308 Muswellbrook 274 347 291 265 289 271 290 317 358 422 Hunter upstream Goulburn 275 346 291 265 290 271 292 316 352 413 Goulburn upstream Sandy Hollow 306 564 562 607 619 684 667 667 1000 - Wybong Creek 359 540 549 651 667 720 731 769 1111 1000 Goulburn upstream Hunter 311 396 357 353 369 346 362 366 405 449 Martiridale Creek 304 392 356 367 369 348 362 366 405 449 RE Saddlers Creek 310 397 368 361 381 355 362 366 404 449 Doyles Creek 307 396 367 362 382 354 361 366 404 449 Saltwater Creek 335 404 376 368 382 355 362 366 404 449 Bayswater Creek 342 413 389 383 401 379 388 395 507 568 Bowmans Creek 338 416 399 390 407 384 388 409 526 568 Glennies Creek 314 399 396 383 403 380 393 397 507 568 Wollombi Brook 292 380 382 384 402 385 397 400 514 568 Loders Creek 292 380 382 385 403 386 397 400 514 568 Singleton - - - - - - - - - Mudies Creek 289 381 383 385 404 387 399 400 514 568 Jump Up Creek 288 381 384 385 404 387 399 400 514 568 Glendon Brook 286 385 389 389 408 390 404 401 514 568 MAINSTREAM DAILY SALT LOADS (tonnes/day) AVERAGE FLOWS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 1288 327 163 96 83 52 37 31 15 4 Glenbawn 424 125 90 52 49 40 26 20 11 3 Rouchel Brook 724 173 111 66 63 46 30 22 11 3 Dart Brook 1503 373 183 104 87 54 38 33 15 4 Muswellbrook 1766 474 228 150 130 97 78 64 43 19 Hunter upstream Goulburn 1803 483 232 153 133 99 80 65 43 19 Goulburn upstream Sandy Hollow 1223 215 113 74 52 39 22 10 2 - Wybong Creek 1744 264 150 112 80 59 38 20 10 3 Goulburn upstream Hunter 3547 747 382 265 213 158 118 85 53 22 Martindale Creek 3647 756 390 270 216 160 118 85 53 22 Saddlers Creek 3769 770 405 277 224 164 118 85 53 22 Doyles Creek 3812 774 407 279 225 164 118 85 53 22 Saltwater Creek 4149 792 417 284 225 164 118 85 53 22 Bayswater Creek 4316 820 441 304 244 181 131 95 69 29 Bowmans Creek 4346 854 464 314 251 184 131 95 69 29 Glennies Creek 4563 913 508 338 268 193 140 97 69 29 Wollombi Brook 4932 984 547 376 292 211 151 103 71 29 Loders Creek 4959 987 548 377 293 212 151 103 71 29 Singleton - - - -. ------Mudies Creek 5086 991 550 378 294 213 152 103 71 29 Jump Up Creek 5165 992 551 379 294 213 152 103 71 29 Glendon Brook 5254 1039 574 391 302 217 156 104 71 29

40 0 0 0 0 41 0 0 0 0 TABLE_A2.7

TRIBUTARY DISCHARGES (ML/d) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 3636 592 215 145 94 66 42 30 14 5 Glenbawn 4963 1240 898 697 515 388 271 173 84 26 Rouchel Brook 2574 337 183 103 75 51 33 14 5 - Dart Brook 1872 283 133 35 12 5 2 - - - Muswellbrook 15070 3199 1853 1327 1053 838 629 473 281 105 Hunter upstream Goulburn 15346 3264 1867 1353 1072 854 641 482 285 108 Goulburn upstream Sandy Hollow 9355 892 470 285 197 133 77 35 5 - Wybong Creek 2010 235 171 117 87 59 47 28 16 7 Goulburn upstream Hunter 11365 1144 639 402 281 192 122 61 21 7 Martindale Creek 1348 108 59 33 16 7 - - - - Saddlers Creek 316 14 9 5 5 2 - - - - Doyles Creek 648 37 16 9 5 2 - - - - Saltwater Creek 229 9 5 2 ------Bayswater Creek 276 66 56 49 42 35 26 19 12 5 Bowmans Creek 480 152 68 30 21 5 - - - - Glennies Creek 3936 557 278 178 115 66 44 9 - - Wollombi Brook 5501 704 346 225 140 96 56 30 5 - Loders Creek 285 12 5 5 2 2 - - - - Singleton 41469 6634 3295 2101 1313 812 517 330 211 133 Mudies Creek 1350 16 7 5 2 2 2 - - - JumpUpCreek 845 5 2 2 - - - - - Glendori Brook 948 213 89 49 30 14 12 5 - - TRIBUTARY SALINITIES (mg/L) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 210 487 450 384 392 177 323 535 549 667 Glenbawn 160 188 188 140 180 194 178 211 236 234 Rouchel Brook 218 266 216 260 343 234 249 206 252 291 Dart Brook 215 305 279 446 595 1002 1133 1015 1025 1046 Muswellbrook 219 278 233 211 231 217 234 252 285 326 Hunter upstream Goulburn 220 277 232 212 231 217 234 22 285 325 Goulburn upstream Sandy Hollow 245 452 451 486 493 546 534 542 636 636 Wybong Creek 486 365 406 614 598 650 651 658 871 824 Goulburn upstream Hunter 287 432 439 521 534 576 585 615 889 800 Martindale Creek 138 161 266 285 346 406 1046 1046 1046 1046 Saddlers Creek 722 1909 3094 2946 3193 3438 3633 3903 3903 3903 Doyles Creek 126 190 211 323 320 347 354 398 630 842 Saltwater Creek 3120 3605 4089 3861 3632 4195 3097 5460 5460 5460 Bayswater Creek 824 805 785 766 832 899 966 1032 2640 2910 Bowmans Creek 115 263 638 595 614 1017 1508 1508 1508 1508 Glennies Creek 103 198 295 248 273 262 377 444 497 497 Wollombi Brook 126 190 211 323 320 347 354 398 630 842 Loders Creek 176 414 487 459 513 476 613 584 661 674 Singleton 213 346 432 464 384 418 424 402 437 489 Mudies Creek 176 414 487 459 513 476 613 584 661 674 Jump Up Creek 176 414 487 459 513 476 613 584 661 674 Glendon Brook 176 414 487 459 513 476 613 584 661 674

0 0 0 0 0 0 0 . . . 0 4 0 9 0 0 .

TABLE A2.9

TRIBUTARY DAILY SALT LOADS (tonnes/day) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 764 288 97 56 37 11 13 17 7 2 Glenbawn 794 234 168 97 92 75 49 37 21 6 Rouchel Brook 562 90 39 26 26 11 7 4 - - Dart Brook 402 86 37 15 7 4 2 - - - Musweilbrook 3306 887 427 281 243 182 146 120 80 36 Hunter upstream Goulburn 3375 904 434 286 249 185 150 122 80 36 Goulburn upstream Sandy Hollow 2289 402 212 139 97 73 41 19 4 - Wybong Creek 975 92 69 71 52 37 30 19 15 6 Goulburn upstream Hunter 3265 494 281 210 150 110 71 37 19 6 Martiridale Creek 187 17 15 9 6 4 - - - - Saddlers Creek 228 26 28 13 15 7 - - - - Doyles Creek 80 7 4 4 2 - - - - - Saltwater Creek 715 34 19 9 ------Bayswater Creek 228 52 45 37 36 32 24 19 30 13 Bowmans Creek 56 64 43 19 13 6 - - - - Glennies Creek 405 110 82 45 32 17 17 4 - - Wollombi Brook 691 133 73 71 45 34 21 11 4 - Loders Creek 50 6 2 2 2 2 - - - - Singleton 8825 2293 1423 975 504 341 219 133 92 66 Mudies Creek 238 7 4 2 2 2 2 - - - JuznpUpCreek 148 2 2 2 ------Glendon Brook 167 88 43 22 15 7 7 2 - - mAflTT, AO Ifl

MAINSTREAM DISCHARGES (ML/d) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95 Pages River 11173 2169 1291 945 684 505 346 217 103 31 Glenbawn 4963 1240 898 697 515 388 271 173 84 26 Rouchel Brook 7537 1577 1076 800 590 439 304 187 89 26 Dart Brook 13018 2452 1429 980 696 510 348 217 103 31 Muswellbrook 15070 3199 1853 1327 1053 838 629 473 281 105 Hunter upstream Goulburn 15346 3264 1867 1353 1072 854 641 482 285 108 Goulburn upstream Sandy Hollow 9355 892 470 285 197 133 77 35 5 - Wybong Creek 11365 1144 639 402 281 192 122 61 21 7 Goulburn and Hunter 26711 4408 2506 1755 1353 1046 763 543 306 115 Martindale Creek 28059 4516 2565 1788 1369 1053 763 543 306 115 Saddlers Creek 28375 4530 2574 1793 1374 1055 763 543 306 115 Doyles Creek 29023 4567 2590 1802 1379 1057 763 543 306 115 Saltwater Creek 29252 4576 2595 1804 1379 1057 763 543 306 115 Bayswater Creek 29528 4642 2651 1853 1421 1092 789 562 318 120 Bowmans Creek 30008 4794 2719 1883 1442 1097 789 562 318 120 Glennies Creek 0 33944 5351 2997 2061 1557 1163 833 571 318 120 Wollombi Brook 39445 6055 3343 2286 1697 1259 889 601 323 120 Loders Creek 39730 6067 3348 2291 1699 1261 889 601 323 120 Singleton ------Mudies Creek 41080 6083 3355 2296 1701 1263 891 601 323 120 Jump Up Creek 41925 6088 3357 2298 1701 1263 891 601 323 120 Glendon Brook 42873 6301 3446 2347 1731 1277 903 606 323 120 TABLE A2.11

MAINSTREAM SALINITIES (mg/L) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 190 282 236 189 227 192 199 267 272 258 Glenbawn 160 189 187 139 179 193 181 214 250 231 Rouchel Brook 180 205 192 154 200 183 184 219 236 231 Dart Brook 194 285 239 198 233 198 204 267 272 258 Muswellbrook 219 277 230 212 231 217 232 254 285 343 Hunter upstream Goulburn 220 277 232 211 232 217 234 253 281 333 Goulburn upstream Sandy Hollow 245 452 451 486 493 546 534 542 636 636 Wybong Creek 287 432 440 522 533 573 582 607 905 857 Goulburn and Hunter 249 317 285 283 295 282 290 293 323 365 Martindale Creek 243 313 285 282 296 284 290 293 324 365 Saddlers Creek 249 318 294 287 306 290 290 393 324 365 M. Doyles Creek 246 317 294 290 306 289 290 293 324 365 Saltwater Creek 268 324 301 294 306 289 290 293 324 365 Bayswater Creek 274 330 312 307 322 310 311 317 406 458 Bowmans Creek 271 333 320 312 327 314 311 317 406 458 Glennies Creek 252 319 317 307 323 310 315 319 406 458 Wollombi Brook 234 304 306 308 323 314 318 321 412 458 Loders Creek 234 304 306 308 324 315 318 321 412 458 Singleton ------Mudies Creek 232 305 307 308 325 316 320 321 412 1008 Jump Up Creek 231 305 307 309 325 316 320 321 412 1008 Glendon Brook 229 309 312 311 328 318 323 322 412 1008 TABLE A2.12

MAINSTREAM DAILY SALT LOADS (tonnes/day) 1 in 10 YEAR WET CONDITIONS AND NO MINE DISCHARGES

Percentage Time Exceedance Tributary 5 15 25 35 45 55 65 75 85 95

Pages River 2120 612 304 179 155 97 69 58 28 8 Glenbawn 794 234 168 97 92 75 49 37 21 6 Rouchel Brook 1356 324 207 123 118 86 56 41 21 6 Dart Brook 2522 698 341 194 162 101 71 58 28 8 Muswellbrook 3306 887 427 281 243 182 146 120 80 36 Hunter upstream Goulburn 3375 904 434 286 249 185 150 122 80 36 Goulburn upstream Sandy Hollow 2289 402 212 139 97 73 41 19 4 - Wybong Creek 3265 494 281 210 150 110 71 37 19 6 Goulburn and Hunter 6640 1398 715 496 399 295 221 159 99 42 Martindale Creek 6827 1415 730 505 405 299 221 159 99 42 Saddlers Creek 7055 1441 758 518 420 306 221 159 99 42 Doyles Creek 7135 1448 762 522 422 306 221 159 99 42 Saltwater Creek 7850 1482 781 531 422 306 221 159 99 42 Bayswater Creek 8078 1534 826 568 458 338 245 178 129 55 Bowmans Creek 8134 1598 869 587 471 344 245 178 129 55 Glennies Creek 8539 1708 951 632 503 361 262 182 129 55 Wollombi Brook 9230 1841 1024 703 548 395 283 193 133 55 Loders Creek 9280 1847 1026 705 550 397 283 193 133 55 Singleton ------Mudies Creek 9518 1854 1030 707 552 399 285 193 133 121 Jump Up Creek 9666 1856 1032 709 552 399 285 193 133 121 Glendon Brook 9833 1944 1075 731 567 406 292 195 133 121

0 0 9 0 0 0 0 0 0 0 APPENDIX 3 DETAILS OF TYPICAL MINES ADOPTED FOR WATER BALANCE MODELLING. 92

TABLE A3.1

DETAILS OF TYPICAL MINES ADOPTED FOR WATER BALANCE MODELLING

tuNE A NINE U NINE C

RON production (Nt) 1.4 to 3..6 5 to 7 0.4 to 6

Groundwater make (NL/year) 36 to 971 475 to 1200 37 to 130

Area of surface haul roads (ha) 26.3 to 29.4 14 to 26 22 to 30

Area of in-pit haul roads (ha) 13.8 to 26.7 14 to 60 7 to 23

Employment 450 550 500

Remarks: A deep pit truck A multiple pit A dragline and shovel oper- truck and shovel strip mine ation. APPENDIX 14 SAMPLE OUTPUT FROM MINEWATER BALANCE MODEL . S S • S S S .

ENTERED PARAMETERS FOR DAMS OF STAGE I

DURATION - 10 YEARS

Initial Minewater Capacity Surface Catchment Runoff Overflow Makeup Dam ID Storage Pumped (m 3 ) Area (m2 ) Area (ha) Coefficient Dam ID Dam ID (m3 ) (%)

1 144000.0 48000.0 1000.0 0.15 27 21 40000.0 0.00 2 135000.0 38500.0 0.0 0.00 22 0 0.0 1.00

DEMANDS DATA FOR STAGE I

DURATION - 10 YEARS

Demand Demand Number of Supply Dam ID Coefficient Supply Dams IDs

1 170.00 1 1 2 76.00 2 2 1 3 1.50 2 2 1 4 1.50 1 1 6 12373.00 1 1 S 94

STAGE 1 MINE DATA

Duration (years) : 1 Annual coal production (Mt ROM/yr) : 1.38 Groundwater make (Ml/a) : 36.50 Area of surface haul roads (ha) : 26.30 Area of in-pit haul roads (ha) : 13.80 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00

STAGE 2 MINE DATA []

Duration (years) : 1 Annual coal production (Mt ROM/yr) : 3.04 Groundwater make (Ml/a) : 244.00 Area of surface haul roads (ha) : 26.90 Area of in-pit haul roads (ha) : 15.40 S Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00

STAGE 3 MINE DATA S Duration (years) 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 434.00 Area of surface haul roads (ha) : 27.30 Area of in-pit haul roads (ha) : 17.00 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00 .

STAGE 4 MINE DATA

Duration (years) : 1 [] Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 606.00 Area of surface haul roads (ha) : 27.90 Area of in-pit haul roads (ha) : 18.50 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00 .

STAGE 5 MINE DATA

Duration (years) : 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 723.00 Area of surface haul roads (ha) : 28.20 Area of in-pit haul roads (ha) 20.00 Rehabilitation area under irrigation (ha) 0.00 Employment (men) : 450.00 S

0 95

STAGE 6 MINE DATA

Duration (years) 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) 766.00 Area of surface haul roads (ha) : 28.50 Area of in-pit haul roads (ha) : 21.20 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00

STAGE 7 MINE DATA

Duration (years) : 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 825.00 Area of surface haul roads (ha) : 28.70 Area of in-pit haul roads (ha) : 22.60 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) 450.00

STAGE 8 MINE DATA

Duration (years) : 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 905.00 Area of surface haul roads (ha) : 28.90 Area of in-pit haul roads (ha) : 23.80 S Rehabilitation area under irrigation (ha) : 0.00 Employment (men) 450.00

STAGE 9 MINE DATA

S Duration (years) : 1 Annual coal production (Mt ROM/yr) : 3.60 Groundwater make (Ml/a) : 953.00 Area of surface haul roads (ha) : 29.20 Area of in-pit haul roads (ha) : 25.20 Rehabilitation area under irrigation (ha) : 0.00 S Employment (men) : 450.00

STAGE 10 MINE DATA

Duration (years) : 1 S Annual coal production (Mt ROM/yr) 3.60 Groundwater make (Ml/a) : 971.00 Area of surface haul roads (ha) : 29.40 Area of in-pit haul roads (ha) : 26.70 Rehabilitation area under irrigation (ha) : 0.00 Employment (men) : 450.00 S

S SUMMARY OF MONTHLY FLOWS ONTO AND OFF THE SITE (Ml/mth)

Inputs Outputs Flows (Ml) Clean Coal Surface Mi newater Haul Overburden Undisturbed Water Stockpiles Facilities Roads Areas Areas Area Average 0.15028E+02 0.32363E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.20578E+02

MEAN MONTHLY STORAGES AND FLOWS FOR ON-SITE DAMS

Mean Storage Mean Overflow Dam Mean Volume Mean Short- (%) (Ml) Used (Ml) fall (Ml)

I 0.22347E+02 0.20578 E+O2 0. 59243E+O2 0.30119E+02 2 0.34732E+02 0.32363 E+O2 0. 57529E+O2 0.43 254E+O1

0 0 0 0 0 0 0 0 . 0 0 0 a . . 0 0 I

SUMMARY OF FLOWS ONTO AND OFF THE SITE BY MONTH FOR EACH MINE STAGE (Ml/mth) Stacie 1

Its Outputs (,141) Clean Surface oa Haul Overburden Water 1inewa t Facilities Undisturbed Stockpiles Area Roads Areas Areas Jan O.24263E+O2 O.3412OE+O2 O.00000E+OO O.00000E+OO O.00000E+OO O.00000E+OO O.37129E+O2 Feb O.25829E+O2 O.29685E+O2 O.00000E+OO O.00000E+OO O.00000E+OO O.00000E+OO O.34397E+O2 Mar 0.24750E+02 0.22181E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.18679E+02 Apr 0.97341E+01 0.24323E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.19793E+02 May 0.90010E+01 0.38785E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.20090E+02 Jun 0.39158E+01 0.41648E+02 O.00000E-'-OO O.00000E+00 OOOOOOE+OO O.00000E+00 0.21858E+02 Jul 0.31764E+01 041321E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.19201E+02 Aug 0.36700E+01 0.36487E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.65040E+01 Sep -0.45896E+01 0.31491E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.12553E+02 Oct 0.13375E+02 0.32341E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.15591E+02 Nov 0.27490E+02 0.30407E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.20371E+02 Dec 0.30538E+02 0.25567E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.20771E+02 Annual 0.15028E+02 0.32363E+02 O.00000E+00 O.00000E+00 O.00000E+00 O.00000E+00 0.20578E+02 APPENDIX 5 SALINITY VALUES IN THE HUNTER RIVER WITH DIFFERENT LEVELS OF MINE DISCHARGES

S

0 TABLE A5.l AVERAGE TRIBUTARY FLOWS WITH MINEWATER DISCHARGES

Tributary 5 15 25 35 45 55 65 75 85 95

PAGES RIVER -Flow 1554 253 92 62 40 28 18 13 6 2 -Salt Load 409 154 52 30 20 6 7 9 4 2 -Concentration 263 609 563 480 490 221 404 669 686 834 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 GLENBAWN -Flow 2121 530 384 298 220 166 116 74 36 11 -Salt Load 424 125 90 52 49 40 26 20 11 3 -Concentration 200 235 235 175 225 242 223 264 295 293 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 ROUCHEL BROOK -Flow 1100 144 78 44 32 22 14 6 2 - -Salt Load 300 48 21 14 14 6 4 2 - - -Concentration 273 333 270 325 429 292 311 258 315 364 -% Change in Conc'n 0 0 . 0 0 0 0 0 0 0 0 DART BROOK -Flow 800.7 121.7 57.7 15.7 5.7 2.7 1.7 0.7 0.7 0.7 -Salt Load 216.1 47.1 21.1 9.1 5.1 3.1 1.4 1.1 1.1 1.1 -Concentration 270 387 366 580 893 1137 823 1500 1500 1500 -% Change in Conctn 0.3 1.5 4.8 3.9 20.0 -9.1 -41.8 N/A N/A N/A MTJSWELLBROOK -Flow 6441.1 1368.1 785.1 568.1 451.1 359.1 270.1 207.1 123.1 47.1 -Salt Load 1767.7 475.7 229.7 151.7 131.7 98.7 79.7 65.7 44.7 20.7 -Concentration 274 348 293 267 292 275 295 317 363 439 -% Change in Conctn 0.1 0.2 0.8 0.7 1.0 1.4 1.0 0.6 1.9 7.9 HUNTER UPSTREAM -Flow 6560.5 1397.5 800.5 580.5 460.5 367.5 276.5 208.5 124.5 48.5 GOULBURN -Salt Load 1806.8 486.8 235.8 156.8 136.8 102.8 83.8 68.8 46.8 22.8 -Concentration 275 348 295 271 297 280 303 330 376 470 -% Change in Conc'n 0.1 0.6 1.5 1.9 2.7 3.2 3.7 4.7 5.5 15.7 GOULBURN UPSTREAM -Flow 3998.6 381.6 201.6 122.6 84.6 57.6 33.6 15.6 2.6 0.6 SANDY HOLLOW -Salt Load 1224.0 216.0 114.0 75.0 53.0 40.0 23.0 11.0 3.0 1.0 -Concentration 306 566 565 612 626 694 683 703 1127 1500 -% Change in Conc'n 0.0 0.1 0.2 0.5 1.6 1.5 2.3 3.8 41.7 N/A

TABLE A5.l (cont'd)

Tributary 5 15 25 35 45 55 65 75 85 95

GOULBURN UPSTREAM -Flow 4857.6 489.6 273.6 172.6 120.6 82.6 52.6 26.6 9.6 3.6 HUNTER -Salt Load 1745.0 265.0 151.0 113.0 81.0 60.0 39.0 21.0 11.0 4.0 -Concentration 359 541 552 655 671 726 745 788 1138 1092 -% Change in Conc'n 0.0 0.2 0.5 0.5 0.6 0.8 1.9 2.4 2.4 2.7 HUNTER AND -Flow 11418.2 1892.2 1074.2 753.2 581.2 460.2 329.2 235.2 134.2 52.2 GOULBURN -Salt Load 3551.8 751.8 386.8 269.8 217.8 162.8 122.8 89.8 57.8 26.8 -Concentration 311.0 397.3 360.0 358.2 374.7 353.7 373.0 381.8 430.7 513.5 -% Change in Conc'n 0.1 0.2 0.9 1.3 1.6 2.3 3.0 4.2 6.4 14.3 MARTINDALE CREEK -Flow 576 46 25 14 7 3 - - - - -Salt Load 100 9 8 5 3 2 - - - - -Concentration 173 201 332 356 432 508 1308 1308 1308 1308 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 SADDLERS CREEK -Flow 135.5 6.5 4.5 2.5 2.5 1.5 0.5 0.5 0.5 0.5 -Salt Load 122.8 14.8 15.8 7.8 8.8 4.8 0.8 0.8 0.8 0.8 -Concentration 906 2263 3477 3067 3459 3110 1500 1500 1500 1500 -% Change in Conc'n 0.3 -5.2 -10.1 -16.7 -13.3 -27.6 N/A N/A N/A N/A 11 DOYLES CREEK -Flow 277 16 7 4 2 1 - - - - -Salt Load 43 4 2 2 1 - - - - - -Concentration 157 237 264 404 400 434 442 497 788 1052 -% Change in Conc'n 0 0 0 o 0 0 0 0 0 0 SALTWATER CREEK -Flow 98.6 4.6 2.6 1.6 0.6 0.6 0.6 0.6 0.6 0.6 -Salt Load 382.9 18.9 10.9 5.9 0.9 0.9 0.9 0.9 0.9 0.9 -Concentration 3882 4073 4128 3602 1500 1500 1500 1500 1500 1500 -% Change in Conc'n -0.4 -9.6 -19.2 -25.3 N/A N/A N/A N/A N/A N/A BAYSWATER CREEK -Flow 119.4 29.4 25.4 22.4 19.4 16.4 12.4 9.4 6.4 3.4 -Salt Load 124.1 30.1 26.1 22.1 21.1 19.1 15.1 12.1 18.1 9.1 -Concentration 1039.4 1024.3 1028.9 987.1 1088.0 1165.0 1218.2 1287.7 2823.9 2669.6 -% Change in Conc'n 0.9 1.8 4.8 3.1 4.6 3.6 0.9 -0.1 -14.4 -26.6

0 0 0 41 41 40 0 0 0 S S S

TABLE A5.1 (cont'd)

Tributary 5 15 25 35 45 55 65 75 85 95

BOWMANS CREEK -Flow 206.0 65.0 30.0 14.0 10.0 3.0 - - - - -Salt Load 31.5 35.5 24.5 11.5 8.5 4.5 - - - - -Concentration 153 538 817 823 852 1497 1500 1500 1500 1500 -% Change in Concn 6.3 1.7 2.5 10.5 10.8 17.7 N/A N/A N/A N/A GLENNIES CREEK -Flow 1682.1 238.1 119.1 76.1 49.1 28.1 19.1 4.1 0.1 0.1 -Salt Load 217.2 59.2 44.2 24.2 17.2 9.2 9.2 2.3 0.2 0.2 -Concentration 129 249 371 318 351 328 482 555 1500 1500 -% Change in Conc'n 0.0 0.6 0.6 2.6 13.0 10.3 2.3 0.0 N/A N/A WOLLOMBI BROOK -Flow 2352.7 302.7 149.7 97.7 61.7 42.7 25.7 14.7 3.7 1.7 -Salt Load 371.6 73.6 41.6 40.6 26.6 20.6 13.6 8.6 4.6 2.6 -Concentration 158 243 278 415 431 482 529 585 1243 1500 -% Change in Conc'n 0.6 2.5 5.3 2.7 7.7 11.0. 19.7 17.7 57.7 N/A LODERS CREEK -Flow 123.1 6.1 3.1 3.1 2.1 21 1.1 1.1 1.1 1.1 -Salt Load 28.7 4.7 2.7 2.7 2.7 2.7 1.7 1.7 1.7 1.7 -Concentration 233 770 871 871 1286 1286 1500 1500 1500 1500 -% Change in Conc'n 5.9 48.6 43.0 51.7 100.6 116.1 N/A N/A N/A N/A MUDIES CREEK -Flow 577 7 3 2 1 1 1 - - - -Salt Load 127 4 2 1 1 1 1 - - - -Concentration 220 518 609 574 641 595 766 730 826 842 -% Change inConc'n 0 0 0 0 0 0 0 0 0 0 JUMP UP CREEK -Flow 361 2 1 1 - - - - - - -Salt Load 79 1 1 1 -. - - - - - -Concentration 220 518 609 574 641 595 766 730 826 842 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 GLENDON BROOK -Flow 405.2 91.2 38.2 21.2 13.2 6.2 5.2 2.2 0.3 0.3 -Salt Load 89.5 47.5 23.5 12.4 8.7 4.0 4.2 1.9 0.4 0.4 -Concentration 221 520 614 583 656 638 797 837 1500 1500 -% Change in Conc'n 0.4 0.4 0.8 1.6 2.3 7.2 4.0 14.6 N/A N/A

* Flow (ML/d) Salt Load (t/d) Concentration (rng/ L) AVERAGE MAINSTREAM FLOWS WITH MINEWATER DISCHARGES

Tributary 5 15 25 35 45 55 65 75 85 95

PAGES RIVER -Flow 4775 927 554 404 292 216 148 93 44 13 -Salt Load 1288 327 163 96 83 52 37 31 15 4 -Concentration 270 353 294 238 284 241 250 333 341 308 - %ChangeinConc'n 0 0 0 0 0 0 0 0 0 0 CLENBAWN Flow- 2121 530 384 298 220 166 116 74 36 11 -Salt Load 424 125 90 52 49 40 26 20 11 3 -Concentration 200 235 235 175 225 242 223 264 295 293 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 ROUCHEL BROOK - Flow 3221 674 462 342 252 188 .130 80 38 11 -Salt Load 724 173 111 66 63 46 30 22 11 3 -Concentration 225 257 240 193 250 245 231 275 289 273 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 DART BROOK _I:low 5575.7 1048.7 611,7 419.7 297.7 218.7 149.7 93.7 44.7 13.7 -Salt Load 1504.1 374.1 184.1 105.1 88.1 55.1 39.1 34.1 16.1 5.1 -Concentration 270 357 301 250 296 252 261 364 361 374 -' Change in Conc'n 0 0.2 0.3 1.0 1.0 1.6 2.5 2.5 5.7 21.4 MUSWELLBROOK -Flow 6441.1 1368.1 785.1 568.1 451.1 359.1 270.1 203.1 121.1 46.1 -Salt Load 1764,9 475.7 229.7 151.7 131.7 98.7 79.7 64.4 44.0 20.2 -Concentration 274 348 293 267 292 275 295 317 363 439 -% Change in Conc'n 0.1 0.2 0.8 0.7 1.0 1.4 1.0 0.6 1.9 7.9 HUNTER UPSTREAM -Flow 6560.5 1397.5 800,5 580.5 460.5 360.5 271.5 204.5 122.3 47.5 GOULBURN -Salt Load 1806.8 486.8 235.8 156.8 136.8 10L8 83.8 68.8 46.8 22.8 -Concentration 275 348 295 271 297 280 303 330 376 470 -% Change in Conc'n 0.1 0.6 1.5 1.9 2.7 3.2 3.7 4.7 5.5 15.7 GOULBURN UPSTREAM -Flow 3998.6 381.6 201.6 122.6 84.6 57.6 33.6 15.6 2.6 0.6 SANDY HOLLOW -Salt Load 1224.0 216.0 114.0 75.0 53.0 40.0 23.0 11.0 3.0 1.0 -Concentration 306 566 565 612 626 694 683 703 1127 1500 -% Change in Conc'n 0.0 0.1 0.2 0.5 1.6 1.5 2.3 3.8 41.7 N/A

S 41 40 0 0 • TABLE A5.2 (cont'd)

Tributary 5 15 25 35 45 55 65 75 85 95

GOULBURN UPSTREAM -Flow 4857.6 489.6 273.6 172.6 120.6 82.6 52.6 26.6 9.6 3.6 HUNTER -Salt Load 1745.0 265.0 151.0 113.0 81.0 60.0 39.0 21.0 11.0 4.0 -Concentration 359 541 552 655 671 726 745 788 1138 1092 -% Change in Conc'n 0.0 0.2 0.5 0.5 0.6 0.8 1.9 2.4 2.4 9.2 HUNTER AND -Flow 11418.2 1892.2 1074.2 753.2 581.2 460.2 329.2 235.2 134.2 52.21 GOULBURN -Salt Load 3551.8 751.8 386.8 269.8 217.8 162.8 122.8 89.8 57.8 26.8 -Concentration 311.0 397.3 360.0 358.2 374.7 353.7 373.0 381.8 430.7 513.5 -% Change in Conc'n 0.1 0.2 0.9 1.3 1.6 2.3 3.0 4.2 6.4 14.3 MARTINDALE CREEK -Flow 11994.2 1933.2 1099.2 739.2 588.2 463.2 329.2 235.2 134.2 52.21 -Salt Load 3645.8 761.8 394.8 274.8 220.8 164.8 122.8 89.8 57.8 26.8 -Concentration 304 394 359 371 375 356 373 382 431 514 -% Change in Conc'n 0.1 0.3 0.8 1.3 1.7 2.2 3.0 4.3 6.3 14.3 SADDLERS CREEK -Flow 12129.7 1939.7 1103.7 769.7 590.7 464.7 329.7. 235.7 134.7 52.7 -Salt Load 3774.6 775.6 410.6 282.6 229.6 169.6 123.6 90.6 58.6 27.6 -Concentration 311.1 399.8 372.0 367.1 388.7 364.9 374.9 384.4 435.1 523.7 -% Change in Conc'n 0.1 0.5 1.0 1.5 1.8 2.6 3.5 4.9 7.5 16.6 DOYLES CREEK -Flow 12406.7 1955.7 1110.7 773.7 592.7 465.7 329.7 235.7 134.7 52.7 -Salt Load 3817.6 779.6 412.6 284.6 230.6 169.6 123.6 90.6 58.6 25.6 -Concentration 307.7 398.6 371.4 367.8 389.1 364.2 374.9 384.4 435.1 485.9 -% Change in Conc'n 0.1 0.5 1.0 1.5 7.3 2.6 3.5 4.9 7.5 8.2 SALTWATER CREEK -Flow 12505.4 1960.4 1113.4 775.4 593.4 466.4 330.4 236.4 135.4 53.4: -Salt Load 4200.6 798.6 423.6 290.6 231.6 170.6 124.6 91.6 59.6 28.61 -Concentration 335.9 407.3 380.4 374.7 390.3 365.8 377.1 387.5 440.2 535.7 -% Change in Conc'n 0.1 0.6 1.1 1.7 2.1 3.0 4.1 5.7 8.8 19.3 BAYSWATER CREEK -Flow 12624.8 1989.8 1138.8 797.8 612.8 482.8 342.8 245.8 141.8 56.8 -Salt Load 4324.7 828.7 449.7 312.7 252.7 189.7 139.7 103.7 77.7 37.7 -Concentration 342.5 416.4 394.9 392.0 412.4 392.9 407.6 422.0 548.1 664.1 -% Change in Conc'n 0.2 0.7 1.4 2.1 2.6 3.5 4.8 6.6 8.0 16.8 TABLE A5.2 (cont'd)

Tributary 5 15 25 35 45 55 65 75 85 95

BOWMANS CREEK -Flow 12830.8 2055.8 1168.8 811.8 622.8 485.8 343.8 246.8 142.8 57.8 -Salt Load 4356.3 864.3 474.2 324.3 261.3 194.3 141.3 105.3 79.3 39.3 -Concentration 339.5 420.4 405.7 399.4 419.5 399.9 410.9 426.5 555.0 679.1 -% Change in Conc'n 0.1 0.8 1.6 2.4 2.9 4.1 5.7 4.1 5.3 19.4 GLENNIES CREEK -Flow 14513.0 2294.0 1288.0 888.0 672.0 514.0 363.0 251.0 143.0 58.0 -Salt Load 4573.5 923.5 518.5 348.5 278.5 203.5 150.5 107.5 79.5 39.5 -Concentration 315.1 402.5 402.5 392.4 414.4 395.9 414.6 428.3 556.0 681.2 -% Change in Conctn 0.1 0.8 1.5 2.2 2.8 4.0 5.4 7.7 9.5 19.8 WOLLOMBI BROOK -Flow 16865.7 2596.7 1437.7 985.7 733.7 556.7 388.7 265.7 146.7 59.7 -Salt Load 4945.1 997.1 560.1 389.1 305.1 224.1 164.1 116.1 84.1 42.1 -Concentration 293.2 383.9 389.5 394.7 415.8 402.5 422.1 436.9 573.1 704.8 -% Change in Conc'n 0.2 0.9 1.7 2.5 3.2 4.5 6.2 9.0 11.4 23.9 LODERS CREEK -Flow 16988.8 2602.8 1440.8 988.8 735.8 558.8 389.8 266.8 147.8 60.8 -Salt Load 4973.7 1001.7 562.7 391.7 307.7 226.7 165.7 117.7 85.7 43.7 -Concentration 292.7 384.8 390.5 396.1 418.2 405.7 425.2 441.3 580.1 719.3 -% Change in Conc'n 0.2 1.1 2.0 2.8 3.6 5.0 7.0 10.1 12.7 26.5 MUDIES CREEK -Flow 17565.8 2609.8 1443.8 990.8 736.8 559.8 390.8 266.8 147.8 60.8 -Salt Load 5100.7 1005.7 564.7 392.7 308.7 227.7 166.7 117.7 85.7 43.7 -Concentration 290.3 385.3 391.1 396.4 419.0 406.8 426.6 441.3 580.1 719.3 -% Change in Conc'n 0.2 1.1 1.9 2.9 3.6 5.0 6.9 10.1 12.7 26.5 JUMP UP CREEK -Flow 17926.8 2611.8 1444.8 991.8 736.8 559.8 390.8 266.8 147.8 60.8 -Salt Load 5179.7 1006.7 565.7 393.7 308.7 227.7 166.7 117.7 85.7 43.7 -Concentration 288.9 385.4 391.5 397.0 419.0 406.8 426.6 441.3 580.1 719.3 -% Change in Conc'n 0.2 1.0 1.9 2.8 3.6 6.7 6.9 10.1 12.7 26.5 GLENDON BROOK -Flow 18332.1 2703.1 1483.1 1013.1 750.1 566.1 396.1 269.1 148.1 60.8 -Salt Load 5269.1 1054.1 589.1 406.1 317.1 232.1 171.1 119.1 86.1 43.7 -Concentration 287.5 389.9 397.2 400.9 422.8 410.1 432.1 442.8 581.8 719.3 -% Change in Conc'n 0.2 1.0 1.9 2.8 3.6 5.0 6.9 10.3 13.0 26.5

* Flow (ML/d) Salt Load (t/d) Concentration (mg/L)

0 0 0 0 0 is • S 0 0 S S S S 0

TABLE A5.3 linlO YEAR TRIBUTARY FLOWS WITH MINEWATER DISCHARGES

Tributary 5 15 25 35 45 55 65 75 85 95

PAGES RIVER -Flow 3636 592 215 145 94 66 42 30 14 5 -Salt Load 764 288 97 56 37 11 13 17 7 3 -Concentration 210 487 450 384 392 177 323 535 549 667 -% Change inConc'n 0 0 0 0 0 0 0 0 0 0 GLENBAWN -Flow 4963 1240 898 697 515 388 271 173 84 26 -Salt Load 794 234 168 97 92 75 49 37 21 6 -Concentration 160 188 188 140 180 194 178 211 236 234 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 ROUCHEL BROOK -Flow 2574 337 183 103 75 51 33 14 5 - -Salt Load 562 90 39 26 26 11 7 4 - -Concentration 218 266 216 260 343 234 249 206 252 291 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 DART BROOK -Flow 1875.8 286.8 136.8 38.8 15.8 8.8 5.8 -Salt Load 405.8 89.8 40.8 18.8 10.8 7.8 5.8 - - - -Concentration 216 313 298 485 684 934 1000 1000 1000 1000 -% Change in Conctn 0.6 1.0 6.9 8.7 14.9 -6.7 -11.7N.A. N.A. N.A. V1USWELLBROOK -Flow 15075.6 3204.6 1858.6 1332.6 1058.6 843.6 634.6 480.6 286.6 110. -Salt Load 3311.6 892.6 432.6 286.6 248.6 187.6 151.6 125.6 85.6 41. -Concentration 220 279 233 215 235 222 239 261 299 376 -% Change in Conctn 0.3 0.2 0.0 1.9 1.7 2.3 2.1 3.7 4.8 is. HUNTER UPSTREAM -Flow 15358.6 3276.6 1879.6 1365.6 1084.6 866.6 653.6 494.6 297.6 120. GOULBURN -Salt Load 3387.6 916.6 446.6 298.6 261.6 197.6 162.6 134.6 92.6 48.6 -Concentration 221 280 238 219 241 228 249 272 311 403 -% Change in Conc'n 0.2 0.9 2.4 3.1 4.4 5.1 6.3 8.0 9.2 24.0 GOULBURN UPSTREAM -Flow 9355 892 470 285 197 133 77 35 5 - SANDY HOLLOW -Salt Load 2289 402 212 139 97 73 41 19 4 - -Concentration 245 452 451 486 493 546 534 542 636 636 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 TABLE A5.3 (cont'd)

Tributary 5 15 25 35 45 55 65 75 85 95

WYBONG CREEK -Flow 2010 235 171 117 87 59 47 28 16 7 -Salt Load 975 92 69 71 52 37 30 19 15 6 -Concentration 486 365 406 614 598 650 651 658 871 824 -ó Change in Conc'n 0 0 0 0 0 0 0 0 0 0 GOULBURN UPSTREAM -Flow 11368.4 1147.4 642.4 405.4 284.4 195.4 125.4 64.4 24.4 10.4 HUNTER -Salt Load 3268.4 497.4 284.4 213.4 153.4 113.4 74.4 40.4 22.4 9.4 -Concentration 288 434 443 526 539 580 593 627 918 904 -% Change in Conc'n 0.2 0.5 0.8 1.0 1.0 0.7 1.4 2.0 3.2 13.0 HUNTER AND -Flow 26727.0 4424.0 2522.0 1771.0 1369.0 1062.0 779.0 559.0 322.0 131.0 GOUL BURN -Salt Load 6656.0 1414.0 731.0 512.0 415.0 311.0 237.0 175.0 115.0 58.0 -Concentration 249.0 319.6 289.8 289.1 303.1 292.8 304.2 313.1 357.2 442.9 -% Change in Conc'n 0.0 0.8 1.7 2.1 2.7 3.8 4.9 6.8 10.6 21.3 MARTINDALE CREEK -Flow 1348 108 59 33 16 7 - - - - -Salt Load 187 17 15 9 6 4 - - - - -Concentration 138 161 266 285 346 406 1046 1046 1046 1046 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 01 SADDLERS CREEK -Flow 318.7 16.7 11.7 7.7 7.7 4.7 - - - - -Salt Load 230.7 28.7 30.7 15.7 17.7 9.7 - - - - -Concentration 724 1716 2616 2031 2289 2051 1000 1000 1000 1000 -% Change in Conc'n 0.2 -10.1 -15.4 -31.0 -28.3 -40.3 N.A. N.A. N.A. N.A. DOYLES CREEK -Flow 648 37 16 9 5 5 2 - - - -Salt Load 80 7 4 4 2 - - - - - -Concentration 126 190 211 323 320 347 354 398 630 842 -% Change in Conctn 0 0 0 0 0 0 0 0 0 0 SALTWATER CREEK -Flow 232.2 12.2 7.2 4.2 - - - - - - -Salt Load 718.2 37.2 22.2 12.2 - - - - - - -Concentration 3092 3035 3059 2867 1000 1000 1000 1000 1000 1000 -% Change in Conc'n -0.8 -15.8 -25.1 -25.7 N.A. N.A. N.A. N.A. N.A. N.A. BAYSWATER CREEK -Flow 283.1 73.1 63.1 56,1 49.1 42.1 33.1 26.1 19.1 12.1 -Salt Load 231.9 55.9 48.9 40,9 39.9 35.9 27.9 22.9 33.9 16.9 -Concentration 819 765 776 730 814 854 844 879 1776 1399 -% Change in Conc'n -0.5 -4.9 -1.1 -4.7 -2.2 -5.0 -12.6 -14.8 -32.7 -51.9

0 0 40 0 40 0 S 0 0 0 0 0 S S

TABLE A5.3 (conttd)

Tributary 5 15 25 35 45 55 65 75 85

BOWMANS CREEK -Flow 485.1 157.1 73.1 35.1 26.1 10.1 - - - -Salt Load 61.1 69.1 48.1 24.1 18.1 11.1 - - - -Concentration 126 440 658 687 694 1098 1000 1000 1000 1 1000 -% Change in Conctn 9.6 67.3 3.1 15.5 13.1 7.9 N.A. N.A. N.A. N.A. GLENNIES CREEK -Flow 3936.7 577.7 278.7 178.7 115.7 66.7 44.7 9.7 - - -Salt Load 405.7 110.7 82.7 45.7 32.7 17.7 17.7 4.7 - - -Concentration 103 192 297 256 283 266 397 488 1000 1000 -% Change in Conc'n 0.2 3.1 0.6 3.2 3.6 1.5 5.2 9.9 N.A. N.A. WOLLOMBI BROOK -Flow 5509.6 712.5 354.5 233.5 148.5 104.5 64.5 38.5 13.5 - -Salt Load 699.5 141.5 81.5 79.5 53.5 42.5 29.5 20.5 13.5 8 -Concentration 127 199 230 341 361 407 458 533 1000 1000 -% Change in Conc'n 0.7 4.5 9.0 5.4 12.6 17.3 29.4 34.0 58.7 N.A. LODERS CREEK -Flow 290.5 17.5 10.5 10.5 7.5 7.5 - - - - -Salt Load 55.5 11.5 7.5 7.5 7.5 7.5 - - - - -Concentration 191 658 715 715 1000 1000 1000 1000 1000 1000 - Change in Conc'n 8.5 58.9 46.8 55.5 94.9 110.0 N.A. N.A. N.A. N.A. MUDIES CREEK -Flow 1350 16 7 5 2 2 2 - - - -Salt Load 238 7 4 2 2 2 2 - - - -Concentration 176 414 487 459 513 476 613 584 661 674 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 JUMP UP CREEK -Flow 845 5 2 2 - - - - - - -Salt Load 148 2 2 2 - - - - - - -Concentration 176 414 487 459 513 476 613 384 661 674 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 C GLENDON BROOK -Flow 949.3 214.3 90.3 50.3 31.4 13.3 6.3 - - - -Salt Load 168.3 89.3 44.3 23.3 16.3 8.3 8.3 - - - -Concentration 177 417 491 464 519 626 1314 1000 1000 100C -% Change in Conc'n 0.7 0.7 0.8 1.0 1.2 31.5 114.4 N.A. N.A. N.A.

* Flow (ML/d) Salt Load (t/d) Concentration (mg/L) mAPlE AC A

linlO YEAR MAINSTREAM FLOWS WITH MINEWATER DISCHARGES

Tributary 5 15 25 35 45 55 65 75 85 95

PAGES RIVER -Flow 11173 2169 1291 945 684 505 345 217 103 31 -Salt Load 2120 612 304 179 155 97 69 58 28 8 -Concentration 190 282 236 189 227 192 199 267 272 258 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 GLENBAWN -Flow 4963 1240 898 697 515 388 271 173 84 26 -Salt Load 794 234 168 97 92 75 49 37 21 6 -Concentration 160 188 188 140 180 194 178 211 236 234 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 ROUCHEL BROOK -Flow 7537 1577 1076 800 590 439 304 187 89 26 -Salt Load 1356 324 207 123 118 86 56 41 21 6 -Concentration 180 205 192 154 200 183 184 219 236 231 -% Change in Conc'n 0 0 0 0 0 0 0 0 0 0 DART BROOK -Flow 13021.8 2455.8 1432.8 983.8 699.8 513.8 351.8 220.8 106.8 34.8 -Salt Load 2525.8 701.8 344.8 197.8 165.8 104.8 74.8 61.8 31.8 11.8 -Concentration 193.9 285.7 240.6 201.0 236.9 204.0 212.6 279.9 297.9 339.6 -% Change in Conc'n 0.0 0.2 0.6 1.5 1.7 3.0 4.2 4.8 9.5 31.6 MUSWELLBROOK -Flow 15075.6 3204.6 1858.6 1332.6 1058.6 843.6 634.6 478.6 286.6 109.6 -Salt Load 3311.6 892.6 432.6 286.6 248.6 187.6 151.6 125.6 85.6 41.6 -Concentration 219.6 278.5 232.7 215.1 234.8 222.4 238.9 262.5 298.8 379.9 - Change in Conc'n 0.3 0.5 0.3 1.4 1.6 2.5 3.0 3.3 6.3 10.7 HUNTER UPSTREAM -Flow 15358.6 3276.6 1879.6 1365.6 1084.6 866.6 653.6 494.6 297.6 120.6 GOULBURN -Salt Load 3387.6 916.6 446.6 298.6 261.6 197.6 162.6 134.6 92.6 48.6 -Concentration 220.5 279.7 237.6 218.6 241.2 228.0 248.8 272.2 311.2 403.2 -% Change in Conc'n 0.2 0.9 2.4 3.6 3.9 5.1 6.3 7.5 10.7 21.0 GOULBURN UPSTREAM -Flow 9358.4 895.4 473.4 288.4 200.4 136.4 81.4 38.4 8.4 SANDY HOLLOW -Salt Load 2292.4 405.4 215.4 142.4 100.4 77.4 44.4 23.4 7.4 -Concentration 245 453 455 494 501 567 545 609 881 1000 -% Change in Conc'n 0.0 0.1 0.8 1.6 1.6 3.9 2.1 12.4 38.5 N/A 0

TABLE A5.4 (cont'd)

Tributary 5 15 25 35 45 55 65 73 85 95

WYBONG CREEK -Flow 11368.4 1143.4 642.4 405.4 284.4 195.4 125.4 64.4 24.4 11.4 -Salt Load 3268.3 497.3 284.3 213.3 153.3 113.3 74.3 40.3 22.3 9.3 -Concentration 288 435 443 526 539 580 593 627 918 824 -% Change in Conc'n 0.1 0.7 0.6 0.8 1.1 1.2 1.9 3.3 1.3 -3.8 GOULBURN UPSTREAM -Flow 11368.3 1147.3 642.3 405.3 284.3 195.3 125.3 64.3 24.3 10.3 HUNTER -Salt Load 3268.3 497.3 284.3 213.3 153.3 113.3 74.3 41.3 23.3 9.3 -Concentration 287.5 433.5 442.7 526.3 539.3 580.3 593.2 642.8 959.0 903.7 -% Change in Conc'n 0.1 0.3 0.8 1.0 1.0 0.7 1.4 2.0 3.2 1.1 HUNTER AND -Flow 26727.0 4424.0 2522.0 1771.0 1369.0 1062.0 779.0 559.0 322.0 131.0 GOULBURN -Salt Load 6656.0 1414.0 731.0 512.0 415.0 311.0 237.0 175.0 115.0 58.0 -Concentration 249.0 319.6 289.8 289.1 303.1 292.8 304.2 313.1 357.2 442.9 -% Change in Conc'n 0.0 0.8 1.7 2.1 2.7 3.8 4.9 6.8 10.6 21.3 MARTINDALE CREEK -Flow 28075.0 4532.0 2581.0 1804.0 1385.0 1069.0 779.0 559.0 322.0 131.0 -Salt Load 6843.0 1431.0 746.0 521.0 421.0 315.0 237.0 175.0 115.0 58.0 -Concentration 244 314 289 289 304 295 304 313 357 443 -% Change in Conc'n 0.3 0.1 1.4 2.4 2.7 3.7 4.9 6.8 10.2 21.3 SADDLERS CREEK -Flow 28393.8 4548.8 2592.8 1811.8 1392.8 1073.8 781.8 561.8 324.8 133.8 -Salt Load 7073.7 1459.7 776.7 536.7 438.7 324.7 239.7 177.7 117.7 60.7 -Concentration 249.1 320.9 299.5 296.2 315.0 302.4 306.7 316.4 362.6 454.2 -% Change in Conctn 0.0 0.9 5.1 3.2 2.9 4.3 5.7 8.0 11.9 24.4 DOYLES CREEK -Flow 29041.8 4585.8 2608.8 1820.8 1397.8 1075.8 781.8 561.8 324.8 133.8 -Salt Load 7153.7 1466.7 780.7 540.7 440.7 324.7 239.7 177.7 117.7 60.7 -Concentration 246 320 299 297 315 302 306 316 363 454 -% Change in Conc'n 0.1 0.9 1.8 2.4 3.0 4.4 5.7 8.0 11.9 24.4 SALTWATER CREEK -Flow 29274.0 4598.0 2617.0 1826.0 1401.0 1079.0 785.0 565.0 328.0 137.0 -Salt Load 7872.0 1504.0 803.0 553.0 444.0 328.0 243.0 181.0 121.0 64.0 -Concentration 268.9 327.1 306.8 302.8 316.9 304.0 309.6 320.4 369.0 467.3 -% Change in Conc'n 0.3 0.9 1.9 3.0 3.5 5.2 6.7 9.3 13.8 28.0 BAYSWATER CREEK -Flow 29557.1 4671.1 2680.1 1882.1 1450.1 1121.1 818.1 591.1 347.1 149.1 -Salt Load 8107.1 1563.1 855.1 597.1 487.1 367.1 274.1 207.1 158.1 84.1 -Concentration 274.2 334.6 319.0 317.2 335.9 327.4 335.0 350.4 455.5 564.1 -% Change in Conc'n 0.1 1.4 2.2 3.3 4.3 5.6 7.7 10.5 12.2 23.1 TABLE A5.4 (conttd)

Tributary 5 15 25 35 45 55 65 75 85 95

BOWMANS CREEK -Flow 30042.3 4828.3 2753.3 1917.3 1476.3 1131.3 823.3 596.3 352.3 154.3 -Salt Load 8168.3 1632.3 903.3 621.3 505.3 378.3 279.3 212.3 163.3 89.3 -Concentration 271.8 338.0 328.0 324.0 342.2 334.4 339.2 356.0 463.5 578.8 -% Change in Conc'n 0.3 1.5 2.5 3.8 4.6 6.5 9.0 12.3 14.1 26.31 GLENNIES CREEK -Flow 33979.1 5386.1 3032.1 2096.1 1592.1 1198.1 868.1 606.1 353.1 155.1 -Salt Load 8574.1 1743.1 986.1 667.1 538.1 396.1 297.1 217.1 164.1 90.1 -Concentration 252.3 323.6 325.2 318.2 337.9 330.6 342.2 358.2 464.7 580.8 -% Change in Conc'n 0.1 1.4 2.5 3.6 4.6 6.6 8.6 12.2 14.4 26.8: WOLLOMBI BROOK -Flow 39488.7 6098.7 3386.7 2329.7 1740.7 1302.7 932.7 644.7 366.7 163.7 -Salt Load 9273.7 1884.7 1067.7 746.7 591.7 438.7 326.7 236.7 176.7 98.7 -Concentration 234.8 309.0 315.2 320.5 339.9 336.7 350.2 367.1 481.8 602.8 -% Change in Conc'n 0.3 1.6 3.0 4.0 5.2 7.2 10.1 14.3 16.9 31.61 LODERS CREEK -Flow 39779.2 6116.2 3397.2 2340.2 1748.2 1310.2 938.2 650.2 372.2 169.2 -Salt Load 3929.2 1896.2 1075.2 754.2 599.2 446.2 332.2 242.2 182.2 104.2 -Concentration 234.5 310.0 316.5 322.2 342.7 340.5 354.1 372.5 489.5 615.8 -% Change in Conc'n 0.2 1.9 3.4 4.6 5.7 8.1 11.3 16.0 18.8 34.4 MUDIES CREEK -Flow 41129.2 6132.2 3404.2 2345.,2 1750.2 1312.2 940.2 650.2 372.2 167.21 -Salt Load 9567.2 1903.2 1079.2 756.2 601.2 448.2 334.2 242.2 182.2 170.2 -Concentration 233 310 317 322 344 342 355 373 490 1006 -% Change in Conc'n 0.2 1.7 3.2 4,6 5.7 8.0 11.0 16.0 18.8 -0.2 JUMP UP CREEK -Flow 41974.2 6137.2 3406.2 2347.2 1750.2 1312.2 940.2 650.2 372.2 169.2 -Salt Load 9715.2 1905.2 1081.2 758.2 601.2 448.2 334.2 242.2 182.2 176.2 -Concentration 231 310 317 323 344 342 355 373 490 1006 -% Change in Conc'n 0.2 1.7 3.4 4.5 5.7 8.0 11.0 16.0 18.8 -0.2 GLENDON BROOK -Flow 42833.6 6351.6 3496.6 2397.6 1781.6 1327.6 953.6 656.6 373.6 170.6 -Salt Load 9889.6 1994.6 1125.6 781.6 617.6 456.6 342.6 245.6 183.6 171.6: -Concentration 230.8 314.0 321.9 325.9 346.6 343.9 359.2 374.0 491.4 1005.7 -% Change in Conc'n 0.8 1.6 3.1 4.8 5.6 8.1 11.2 16.1 19.2 -0.21

* Flow (ML/d) Salt Load (t/d) Concentration (mg/L) ff 0 0 0 0 0 41 S S 40 0 0 m

C c-fl