Water and Environment

WEST CANNING BASIN MODEL DESIGN REPORT Prepared for Department of Water Date of Issue 1 May 2009 Our Reference 1033/B/021c

WEST CANNING BASIN MODEL DESIGN REPORT Prepared for Department of Water Date of Issue 1 May 2009 Our Reference 1033/B/021c

WEST CANNING BASIN MODEL DESIGN REPORT CONTENTS

CONTENTS

1 INTRODUCTION ...... 1 1.1 Background ...... 1 1.2 Objectives of the Overall Study ...... 1 1.3 Scope of Work ...... 1

2 EXISTING ENVIRONMENT ...... 5 2.1 Climate...... 5 2.2 Geology ...... 5 2.2.1 Regional Geological Structure ...... 5 2.2.2 Wallal Sandstone ...... 6 2.2.3 Jarlemai Siltstone...... 6 2.2.4 Broome Sandstone ...... 6 2.3 Hydrogeology ...... 7 2.3.1 Broome Sandstone ...... 7 2.3.2 Wallal Sandstone ...... 7 2.3.3 Springs...... 7

3 DATA REVIEW ...... 11 3.1 GSWA Investigation (1979) ...... 11 3.2 Petroleum Wells ...... 11 3.3 DoW Water Resources Information Catalogue...... 11 3.4 Moly Mines & BHP Billiton Investigations ...... 11 3.5 Atlas Iron Investigations at Pardoo Station...... 12

4 CONCEPTUAL HYDROGEOLOGY ...... 19 4.1 Introduction ...... 19 4.2 Broome Sandstone (Unconfined Aquifer)...... 19 4.2.1 Aquifer Properties ...... 19 4.2.2 Recharge ...... 19 4.2.3 Groundwater Flow ...... 20 4.3 Jarlemai Siltstone (Aquitard)...... 20 4.4 Wallal Sandstone (Confined Aquifer) ...... 25 4.4.1 Aquifer Properties ...... 25 4.4.2 Recharge ...... 26 4.4.3 Groundwater Flow ...... 26 4.5 Springs...... 26 4.6 Hydrochemistry ...... 37 4.6.1 Broome Sandstone ...... 37

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WEST CANNING BASIN MODEL DESIGN REPORT CONTENTS

4.6.2 Wallal Sandstone ...... 37 4.6.3 Springs...... 37 4.7 Conceptual Model ...... 43

5 NUMERICAL MODEL ...... 51 5.1 Code Selection...... 51 5.2 Model Set Up ...... 51 5.3 Model Extent, Layering and Grid ...... 51 5.4 Boundary Conditions...... 53 5.5 Aquifer Parameters...... 54 5.6 Model Calibration ...... 54

6 REFERENCE LIST ...... 61

TABLES

Table 2.1: Summary of Climate Data...... 5 Table 3.1: Summary of GSWA Drilling Investigation (Leech, 1979) ...... 13 Table 3.2: Summary of Petroleum Wells ...... 14 Table 3.3: Summary of Shay Gap Borefield & Spinifex Ridge Borefield...... 15 Table 3.4: Summary of Pardoo Borefield Investigation ...... 16 Table 4.1: Summary of Lithology at GSWA10A and Pardoo ...... 25 Table 4.2: Summary of Field Water Quality Analysis (DoW, 2009) ...... 38 Table 4.3: Summary of Laboratory Water Quality Analysis (DoW, 2009)...... 39 Table 5.1: Summary of Groundwater User Interface ...... 52 Table 5.2: Layer Geometry ...... 53 Table 5.3: Model Domain...... 53 Table 5.4: Initial Aquifer Parameter Estimates ...... 54

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WEST CANNING BASIN MODEL DESIGN REPORT CONTENTS

FIGURES

Figure 1.1: Location Plan ...... 3 Figure 2.1: West Canning Basin Project Surface Geology ...... 9 Figure 3.1: West Canning Basin Bore Location Plan ...... 17 Figure 4.1: Broome Sandstone Thickness...... 21 Figure 4.2: Alluvium/Broome Sandstone Water Levels ...... 23 Figure 4.3: Jarlemai Siltstone Thickness ...... 27 Figure 4.4: Wallal Sandstone Unconfined & Artesian Boundaries ...... 29 Figure 4.5: Wallal Sandstone Thickness ...... 31 Figure 4.6: Wallal Sandstone Hydraulic Conductivity Distribution ...... 33 Figure 4.7: Wallal Sandstone Potentiometric Surface ...... 35 Figure 4.8: Expanded Durov...... 41 Figure 4.9: Generalised Conceptual Hydrogeology ...... 45 Figure 4.10: Generalised Conceptual Hydrogeology in the West of the Project Area ...... 47 Figure 4.11: Section Location Plan ...... 49 Figure 5.1: Model Extent and Boundary Conditions (Broome Aquifer) ...... 55 Figure 5.2: Model Extent and Boundary Conditions (Wallal Aquifer)...... 57 Figure 5.3: Schematic Boundary Conditions Set Up ...... 59

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WEST CANNING BASIN MODEL DESIGN REPORT INTRODUCTION

1 INTRODUCTION

1.1 BACKGROUND The onshore Canning Basin underlies an area of more than 530, 000km2 in the north of Western Australia. The western most part of the Canning Basin, the West Canning Basin, covers an area of around 9,400km2 and comprises a substantial groundwater resource that is largely untapped. The majority of the Canning Basi n is fairly remote, however, the proxi mity of the West C anning Basin to the town of Port Hedl and and a number of exi sting a nd proposed mi ning oper ations means that the groun dwater resourc e i s comi ng under i ncreasing deman d for mi ne water supplies, public water supply and irrigation. The West Canning Basin area for this Project is shown in Figure 1.1. This project being undertake n by the Department of Water (DoW) is part funed by the Australian Government under its $12.9 billion Water for the Future plan. It will ensure water is available for continued growth of the mining industry, whilst allowing water for sustai nable existence of envi ronmental and cul tural features. A regi onal scal e numerical model of the West Canning Basin is one of the regional tools required by the DoW to allow them to support regional water management objectives. The overall scope of this Project is to devel op a be tter un derstanding of the hydro geology and groundwate r resources of the West Canning Basin on a regi onal scale and to develop a numer ical model that can be us ed by the DoW to assess potential impacts of future abstraction on groundwater resources. 1.2 OBJECTIVES OF THE OVERALL STUDY The p rincipal o bjectives of t he o verall W est Ca nning Ba sin Modelling s tudy, wh ich will b e undertaken in stages, are to: ▼ Improve understanding of the hydrogeology of the West Canning Basin. ▼ Refine basin boundaries and basin geometry over the Project area. ▼ Improve understanding of groundwater flow patterns. ▼ Assess groundwater-surface water interaction, particularly with regard to mound springs. ▼ Evaluate the i mpact of exi sting and proposed gro undwater abstracti on on groundwater storage across the basin. ▼ Evaluate the impact of climate change on the groundwater resources.

1.3 SCOPE OF WORK The scope of work for th is stage of th e Project i s to devel op a conceptual model for the Wes t Canning Basin. This report presents and discusses the essential hydrogeological features of the West Ca nning Basin and p resents a co nceptual hydrogeol ogical model. A preferred nu merical model ling package is identified, and recommenda tions are gi ven for model set up such as model domain, boundary conditions and layer configurations. The report has been structured in the following order: ▼ Existing environment. ▼ Conceptual hydrogeology. ▼ Numerical model.

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LOCATION MAP

LEGEND Town

Project Area

MandoraMandora WallaiWallai DownsDowns

PardooPardoo DeDe GreyGrey

PortPort HedlandHedland MountMount GoldsworthyGoldsworthy

ShayShay GapGap MineMine

CallawaCallawa YarrieYarrie

FIGURE 1.1 LOCATION PLAN

MarbleMarble BarBar AUTHOR: KMH REPORT NO: 021 DRAWN: KMH REVISION: c DATE: 5/03/2009 SCALE: 1:1,500,000 JOB NO: 1033B PROJECTION: GDA94 (Z51) Location: F:\Jobs\1033B\MapInfo\021c_fig1.1.WOR

WEST CANNING BASIN MODEL DESIGN REPORT EXISTING ENVIRONMENT

2 EXISTING ENVIRONMENT

2.1 CLIMATE The West Canning Basin is located in the Pilbara district of Western Australia. The climate in the Pilbara district is classified as arid tropical, characterised by hot summers from October t o April and mil d winters from May to September. Evaporati on i s hi gh, wi th mean annu al pan evaporation rates much larger than mean annual rainfall. Rainfall in t he P ilbara is h ighly va riable a nd la rgely d riven b y c yclonic e vents a nd lo calised thunderstorms between December and March. Meteorol ogical data i s col lected at Pardo o Station (station number 0 04028), l ocated i n the north west of the Project a rea, and Ma ndora Station (station number 004019), l ocated i n the north east o f the Project area. Long-term mean annual rainfall at Pardoo sta tion is 314.9mm, with an average of 1 6 rain days per year. Whilst the l ong-term mean annual rainfall at Mandora stati on is approximately 370.9mm, wi th an average of 19 rain days per year. Climate data for both stations is summarised in Table 2.1.

Table 2.1: Summary of Climate Data

Month Mean Rainfall (mm) Mean Maximum Temperature (°C) Pardoo Station Mandora Station Pardoo Station Mandora Station

January 59.2 81.4 36.4 36.0 February 75.0 101.6 35.4 35.5 March 63.4 74.5 36.1 36.9 April 19.9 21 35.4 36.1 May 24.9 25.3 31.7 32.1 June 27.3 17.4 28.2 29.0 July 9.5 8.4 27.9 28.8 August 5.0 2.6 30.0 30.7 September 2.7 0.9 32.9 33.7 October 0.8 1.2 35.4 35.8 November 3.3 6.5 36.4 36.6 December 23.0 31.5 36.0 36.8

Annual Total 314.9 370.9 - -

2.2 GEOLOGY 2.2.1 REGIONAL GEOLOGICAL STRUCTURE As previously mentioned, the Canni ng Basin extends over 53 0,000km2, of whi ch approximately two-thirds is onshore. Sediments of the basin range in age from Ordovician (approximately 450 million years ago) to Quaternary, reachi ng a ma ximum cum ulative thi ckness of over 8km . Deposition in the Cann ing Basi n co mmenced i n the earl y Ordovician, with a seri es of transgression and regr ession cycles and tectoni c movement sha ping the basi n. The ri fting and break-up bet ween Au stralia a nd a fo rmerly a djoining c ontinental mass, r esulted in a transgression from the northwest. Up to 700m of Early Jurassic to Early Cretaceous sedi ments are preserved onshore and up to 4,000m offshore.

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WEST CANNING BASIN MODEL DESIGN REPORT EXISTING ENVIRONMENT

The area i ncluded in this Project covers a small portion in the s outhwest of the Canni ng Basin and i s confined to the western part of the A nketell Sh elf. T his in cludes t he n orthwesterly trending Wallal Platform (to the west of the Willara Platform), which is a basement high in this area of the Canni ng Bas in. Investi gations by Leech (1979) discovered a s teepening i n the gradient of t he bedrock fl oor in the no rtheast area of the West Canning Basin, suggesti ng that this structure may be a n anci ent faul t scarp, or a hi nge li ne wi th greater subsi dence to the northeast. During the Permi an era, the gl acigene Grant F ormation, of Sakmari an age, was unconformabl y deposited on the Archaea n basement rocks i n the east of the West Canni ng Basi n. This was followed by the deposition of the Dora Shale (Late Sakmarian or Early Artinskian), a continental sequence of claystone, siltstone and sandstone. At the end of the Permian, an interval of uplift occurred and sedimentation ceased (Leech, 1979). During the Mi ddle Jurassi c, renewed subsi dence resulted i n mari ne transgressi on acr oss the West Canning Basin. An unnamed claystone unit was deposited locally on Archaean basement. Further subs idence occurred duri ng the Call ovian, duri ng which the Wallal Sandstone was deposited. This sandsto ne occurs ov er most of t he Canni ng Basi n as the basal uni t of th e Jurassic marine transgression, and was deposited unconformably on Archaean or Permian rocks. Further tran sgression du ring the Oxfordi an resul ted i n the m arine Jarl emai Sil tstone bei ng disconformably deposi ted on the Wall al Sandstone i n a rel atively low energy envi ronment (Leech, 1979). During the Upper Juras sic and Early Cretaceous, the regressi ve Broome S andstone was deposited i n a non-mari ne hi gh ener gy envi ronment. S ince the Earl y Cretaceous, upl ift an d erosion has taken place with only very minor deposition (Leech, 1979). The stratigraphic units most relevant to this Project are the Wallal Sandstone, Jarlemai Siltstone and Broome Sandstone. These sediments generally thicken and deepen to the northeast. Brief descriptions of these units are provided below. Figure 2.1 presents the geology in the West Canning Basin area. 2.2.2 WALLAL SANDSTONE The Wallal Sandstone generally comprises very coarse to fi ne grained sands, which are beige to light grey i n col our. Congl omerate i s common t owards the base of the f ormation, co ntaining quartz, quartzi te, jasper and other pebbl es. A f ine to medium grained sandsto ne an d interbedded mudstone, consistent throughout th e upper Wallal Sandstone has been cor related with the Alexander For mation. T he Wal lal Sandstone ge nerally overli es Pre-Cambri an basement, however in the northeast of the West C anning Basin, faulting has resulted in deeper basin d evelopment a nd t he W allal Sandstone is u nderlain b y t he Do ra Sh ale a nd G rant Formation (Leech, 1979). The Wallal Sandstone is considered to be Jur assic in age and has a maximum recorded thickness of 420m in northeast of the West Canning Basin. 2.2.3 JARLEMAI SILTSTONE The Jarlemai Siltstone comprises mainly black puggy clay and si lty clay, which is light grey t o black i n colour. Thi s unit i s present t hroughout the West Cann ing Basi n, except to the s outh where it pinches out. The Jarlemai Siltstone has a maximum recorded thickness of 200m in the West Canning Basin. 2.2.4 BROOME SANDSTONE The Broome Sandstone is correlated as part of the Callawa Formation and outcrops as isolated mesas of cr oss-bedded sandstone a nd congl omerate a cross the basin. Th e uni t largely comprises poorly consolidated interbedded sequences of fi ne to coarse gr ained, sub-angular to rounded quartz grai ns w ith weak ferrugi nous cement. Mi nor bands of sha le or sil tstone may also occur (Leech, 1979). The Broome Sandstone has a maximum thickness of 62m in the West Canning Bas in area. Cl oser to the coast, th e Broome S andstone i s overlai n by the Bossut Formation, comprising li thified dun e sands a nd l imestone. The B roome Sandstone disconformably overl ies the Jarl emai Siltstone ov er most of the basi n, except for the basin margins, where th e Jarl emai Sil tstone pi nches out and the Br oome S andstone i s thoug ht t o overlie the Wallal Sandstone or unconformably sit against the Archaean basement.

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2.3 HYDROGEOLOGY The Proje ct area i s domi nated by two mai n aqui fer systems h osted i n the largely unconfi ned Broome Sandstone and the confined Wallal Sandstone. These two aquifers are separated by the generally impermeable Jarlemai Siltstone. 2.3.1 BROOME SANDSTONE The fl ow system i n the Broome Sandstone i s general ly unc onfined, w ith groundwat er fl ow direction general ly northwards towar d the Indi an Ocean. Groundwater r echarge i s mainly through di rect percol ation from rai nfall or i ndirectly through the thi n Terti ary or Quaternary sediments. Water l evels are o bserved to fl uctuate wi th heavy rai nfall events. Groundwater discharge is to the Indian Ocean and by evapotranspiration in the low lying coastal area. 2.3.2 WALLAL SANDSTONE The Alexander Formation and Wallal Sandstone are confined beneath the Jarlemai Siltstone over most of the West Canning Basin, with much of the aquifer demonstrating artesian heads of up to 30m above ground level toward the coast. Grou ndwater recharge occurs mainly in the south of the main Canning Basin where the Jarlemai Siltstone is absent and the unit i s unconfined. A smaller component of recharge wi ll also occur al ong the southern margi n of the West Canni ng Basin where the Jarl emai Sil tstone i s al so absent. Groundwater fl ow direction is west- northwesterly, indicating the i mportance of groundwater throu ghflow from the mai n Ca nning Basin. G roundwater d ischarge is like ly t o o ccur via ve rtical s eepage t o ove rlying u nits a nd through sub-marine springs at an unknown distance offshore. 2.3.3 SPRINGS A number of springs (seepage areas) are present along the coast in the Project area. They have generally been excavated to provi de water for stock and are not free-fl owing. Di scharge from these springs is via evapotranspiration and stock watering. The source of these s prings is currently unclear, however, they appear to b e chemically closer to the Wal lal Sandstone groundwater type than the unconfi ned Broome Sandstone. Thi s is discussed further in Section 4.6.

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LOCATION MAP 

Legend Project Area

Fault

Canning Basin

JKc: Callawa Formation AgM: Muccan Granitoid Complex AG: Unassigned Rocks AW: Undivided Rocks AG(c): Paddy Market Formation and Nimingarra Formation AgL: Pippingarra Granitoid Complex

F a u l Fault t Fa u AG(c)AG(c) lt ult Fa F a u lt APAP AgIAgI APAP JKcJKcJKc F AG(c)AG(c) a AG(c)AG(c) u

l t

AWAW FIGURE 2.1 West Canning Basin Surface Geology

AgLAgL F AUTHOR: KMH REPORT NO: 021c AgLAgL a ul DRAWN: KMH REVISION: c AGAG t AgMAgM DATE: 5/03/2009 SCALE: 1:1,000,000 JOB NO: 1033B PROJECTION: MGA94 Location: F:\Jobs\1033B\MapInfo\021c_Figure2.1.WOR (Z50/51)

WEST CANNING BASIN MODEL DESIGN REPORT DATA REVIEW

3 DATA REVIEW

3.1 GSWA INVESTIGATION (1979) A w idespread hydrogeol ogical investigation was conducted in the south-west area of the Canning Ba sin in t he l ate 1 970’s, p roviding c omprehensive h ydrogeological in formation regarding th e Wal lal S andstone, Jarl emai Sil tstone and Broome S andstone ( Leech, 1 979). A total of 47 b ores were drilled duri ng t his investi gation in order to defi ne the strati graphy and derive aqui fer characteri stics. Of th e 47 bores drilled, 40 were cased for future u se and monitoring purposes. It is not known if all these bores are still open. This investigation largely focussed on the western limits of the Canni ng Ba sin, with the most easter n dri lling tra nsect located near the S hay Gap borefi eld. The i nformation in thi s report i s l argely based o n the findings of this investigation. Table 3.1 provides a summary of the bores drilled, with locations displayed on Figure 3.1. In addi tion to the above dri lling programme , a l arge scal e geophysi cal survey has bee n conducted on the West Ca nning Basin area (Rowston, 1976). This geophysical survey included seismic r efraction a nd r esistivity s urveys a nd p rovides in formation r egarding dep ths t o basement and changes in basement lithology.

3.2 PETROLEUM WELLS A number of wel ls have been drilled throughout t he Canni ng Basi n si nce the earl y 1920’s i n search for hydrocarbon re serves (Apak, S and Ca rlsen, G, 1997). The majority of these wells were drilled in the northeast of the Canni ng Basin, with only a few located in the northeast of the West Ca nning Basi n. Tabl e 3.2 provides a s ummary of t he petrol eum well s drilled i n the West Canning Basin area; locations are shown i n Figure 3.1. T hese bores provide information regarding depths and thi cknesses of stratigraphic sequ ence i ntercepted an d assi st i n defi ning the basin geometry in the northeast area of West Canning Basin. A single petroleum well, known as Pa ndanus, is located in the southeast of the West Ca nning Basin. This well was dri lled to a depth of 214m, however, no li thological information has be en found for this well and there is limited information available regarding stratigraphy.

3.3 DOW WATER RESOURCES INFORMATION CATALOGUE A data sear ch was conducted through the Department of Water’s (Do W) Water Resource Information (WIN) Catalogue for hydrogeological information, such as drilled depths, lithological logs, water levels and water quality data, in the Project area. This search returned a number of drill holes in the area around the De Grey River, Pardoo station, Shay Gap, and al ong the coast to Mandora. The location of these bores is presented Figure 3.1.

3.4 MOLY MINES & BHP BILLITON INVESTIGATIONS BHP Bil liton own and op erate S hay Gap borefield l ocated i n the south of the Project area , approximately 165km east of Port Hedl and (Figure 3.1). The borefi eld was established in 1993 to supply the former township of Shay Gap. The borefield currently supplies potable and raw water abstra cted from the Wal lal Sandstone to BHPB’s Yarri e mi ne and c amp. S hay Gap borefield compri ses four non-artesi an producti on bores (PB 1, PB2, PB 3 a nd PB4 ), and o ne centrally located observation bore (OB1). In addition, Moly Mines have conducted hydrogeological investigations in the area approximately 10km east o f the S hay Gap borefield, i n order t o l ocate a w ater sup ply for thei r prop osed molybdenum-copper mi ne at S pinifex Ri dge. Four e xploration b ores we re drilled in t he M oly Mines Project area and an additional two producti on bores were drilled and constructed to fully penetrate the Wallal Sandstone (Aquaterra, 2007). Table 3. 3 provides a su mmary of the BHPB S hay Gap bores and Mol y M ines S pinifex Ri dge bores.

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WEST CANNING BASIN MODEL DESIGN REPORT DATA REVIEW

3.5 ATLAS IRON INVESTIGATIONS AT PARDOO STATION Atlas I ron h ave c onducted h ydrogeological investigations in t he P ardoo s tation a rea approximately 120km east of Port Hed land, in order to l ocate a water suppl y for their proposed magnetite project (Figure 3.1). The h ydrogeological investigation included the installation of a trial producti on bore, two deep moni toring bores i nto the artesi an Wall al Sandstone an d one shallow monitoring bore in the unconfined Broome Sandstone (Aquaterra, 2009). The results of the hydroge ological investigation con firmed aqui fer geometry and characteri stics assessed by Leech (1979). Table 3.4 summarises the Atlas Iron bores constructed in the vicinity of Pardoo station.

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Table 3.1: Summary of GSWA Drilling Investigation (Leech, 1979)

Bore ID Easting Northing Zone Drilled Elevation Top of Top of Top of Base of (MGA94) (MGA94) Depth (m) (mRL) Broome Jarlemai Wallal Wallal (mRL) (mRL) (mRL) (mRL)

1 746658 7763314 50 83.2 19.66 NP NP 19.66 -43.3 2D 752279 7767694 50 104 31.06 31.06 -1.9 -9.9 -71.9 3A 756729 7770638 50 103.4 19.17 19.17 -16.8 -35.8 -70.8 4A 763841 7775365 50 133.5 12.68 12.68 -26.3 -62.3 -104.3 5A 790479 7756603 50 43.5 64.71 64.71 52.7 38.7 24.7 6A 791229 7763730 50 78.5 48.27 48.27 18.3 3.3 -24.7 7A 791580 7770370 50 125 34.23 34.23 7.2 -22.8 -84.8 8A 791343 7777015 50 183 15.12 15.12 -14.9 -60.9 -142.9 9D 791463 7784721 50 224 7.08 7.08 -64.9 -113.9 -211.9 10A 780822 7771956 50 116.4 20.98 20.98 0 (sea level) -20 -92.0 11A 771511 7772501 50 129.7 19.73 19.73 -16.3 -56.3 -77.3 12A 767281 7764827 50 45.7 32.17 32.17 -7.8 NP - 13A 756724 7761795 50 69.7 46.1 46.1 -6.9 NP - 14A 780421 7762976 50 77.1 53.7 53.7 43.7 17.7 -18.3

15A 807933 7761586 50 120.5 84.31 84.31 61.3 21.3 -29.7 16A 807985 7773501 50 184 41.98 41.98 -3 -49 -138.0 17A 809046 7784928 50 259 18.75 18.75 -54.3 -118.3 -234.3 18A 823148 7749194 50 126.5 157.64 157.64 119.6 104.6 35.6 19A 823213 7762253 50 176 105.92 105.92 54.9 26.9 -69.1 20A 823474 7770163 50 215 77.06 77.06 20.1 -30.9 -137.9 21A 823723 7778421 50 235 37.88 37.88 -5.1 -74.1 -189.1

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WEST CANNING BASIN MODEL DESIGN REPORT DATA REVIEW

Bore ID Easting Northing Zone Drilled Elevation Top of Top of Top of Base of (MGA94) (MGA94) Depth (m) (mRL) Broome Jarlemai Wallal Wallal (mRL) (mRL) (mRL) (mRL) 22A 823918 7786784 50 344 11.08 11.08 -44.9 -113.9 -331.9 23A 836223 7768745 50 210 70.91 70.91 46.9 3.9 -100.1 24A 836488 7777527 50 267 43.77 43.77 2.8 -71.2 -222.2 25C 836954 7788139 50 696 16.21 16.21 -38.8 -133.8 -322.8

Note: NP=Not Present. – Indicates where no data available

Table 3.2: Summary of Petroleum Wells

Bore ID Easting Northing Zone Drilled Elevation Top of Top of Top of Wallal Base of (MGA94) (MGA94) Depth (m) (mRL) Broome Jarlemai (mRL) Wallal (mRL) (mRL) (mRL) Samphire Marsh 1 309342 7840589 51 2031.2 4.9 -36 -165.1 -257 -683 BMR 04A Mandora 263269 7816079 51 679 9 -11 -106 -183 -540 Wallal Corehole 1 252137 7801963 51 309.1 24.5 12.3 -60.9 -189 -

Chirup 1 231471 7803245 51 762.6 3.1 -3.4 -136.3 -157 -496 Corbett 1 250328 7779231 51 800 80 - - 77 -244 Pandanus 260382 7739597 51 214 210 - - - -

Note: – Indicates where no data available

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Table 3.3: Summary of Shay Gap Borefield & Spinifex Ridge Borefield

Bore ID Easting Northing Zone Drilled Elevation Top of Top of Top of Base of Comment (MGA94) (MGA94) Depth (m) (mRL) Broome Jarlemai Wallal Wallal (mRL) (mRL) (mRL) (mRL)

PB1 216225 7748913 51 126 133 - - 122 - Shay Gap borefield PB2 215246 7748959 51 126 133 - - - - Shay Gap borefield PB3 215824 7748003 51 115.8 137 - - 133 - Shay Gap borefield OB1 215725 7748580 51 128 133 - - - - Shay Gap borefield PB4 215719 7749685 51 116.4 148 148 - 133 31 Shay Gap borefield MMCA01E* 213731 7758337 51 174.5 105 105 86 62 -63 Spinifex Ridge MMCA01P* 213753 7758335 51 140.4 105 105 86 62 -63 Spinifex Ridge MMCA03E* 213847 7753667 51 146.1 125 125 115 89 -20 Spinifex Ridge MMCA13E* 220725 7757936 51 186 127 127 90 66 -58 Spinifex Ridge MMCA13P* 220724 7757947 51 175 127 127 86 68 - Spinifex Ridge MMCA16E* 213675 7748337 51 120 162 162 NP 104 44 Spinifex Ridge

Note: NP=Not Present. – Indicates where no data available * Data provided by Moly Mines Pty Ltd

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WEST CANNING BASIN MODEL DESIGN REPORT DATA REVIEW

Table 3.4: Summary of Pardoo Borefield Investigation

Bore ID Easting Northing Zone Drilled Elevation Top of Top of Top of Wallal Base of Comment (MGA94) (MGA94) Depth (m) (mRL)* Broome Jarlemai (mRL) Wallal (mRL) (mRL) (mRL)

PB1 781859 7771817 51 101 26 21 2 -17 -72 Production Bore MB1 781852 7771812 51 28 26 20 2 Not Not Shallow Encountered Encountered Monitoring Bore MB2 781876 7771832 51 102 26 21 0 -16 -72 Deep Monitoring Bore

MB3 783011 7773626 51 116 23 18 -11 -27 -91 Deep Monitoring Bore

Note: * Approximate elevation Data provided by Atlas Iron Ltd

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021 c MGA94 (Z50/51) 1:1,000,000 REPORT NO: REVISION: SCALE: PROJECTION: BHPB Shay Gap Borefield Moly Mines Spinifex Ridge Atlas Iron Pardoo Bores Atlas Iron Bores GSWA Bores Petroleum Wells DoW WIN Database Bores Moly Mines Spinifex Ridge Bores Project Area 5/03/09 KMH KMH 1033B Legend LOCATION MAP

AUTHOR: DRAWN: DATE: JOB NO: FIGURE 3.1 Bore Location Plan

E E E 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 0 0 0 3 3 3 E E E 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 0 0 0 3 3 3 E E E 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 0 0 0 3 3 3

N N N

N N N

N N N

N N N N N N

N N N

N N N

N N N

N N N

N N N

N m m m N N

m m m N N N

m m m

m m m m m m

m m m

m m m

m m m

m m m

0 0 0

0 0 0

0 0 0

0 0 0 0 m 0 0 m m

0 0 0

m m 0 0 0 m

0 0 0

m m m

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0 0 0 0 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0 0 0 0 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0 0 0 0 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

0 0 0

5 5 5

0 0 0 0 5 0 0 5 5

5 5 5

0 0 0 5 5 5

5 5 5

0 0 0

5 5 5

8 8 8

8 8 8

7 7 7

8 8 8

7 0 7 7 0 0

8 8 8

0 0 7 7 7 0

8 8 8

0 0 0

8 8 8

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7 7 7 7

7 7 7

7 7 7 7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

E E E 250000m 250000m 250000m E E E 250000m 250000m 250000m E E E 250000m 250000m 250000m

mE mE mE 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 mE mE 0 mE 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 2 mE mE mE 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2

E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 E 1 E 1 1 E m m m 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 E E 1 E 1 1 m m m 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 1 1 1

E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E E E 1 1 1 m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E E 1 E 1 1 m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 Location: F:\Jobs\1033B\MapInfo\021c_Fig3.1.WOR

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

4 CONCEPTUAL HYDROGEOLOGY

4.1 INTRODUCTION The concept ual hydrogeol ogy of the West Canni ng Basi n i s based on th e i ntegration of all available information. T he conceptu al hydrogeo logy was l argely based on the resul ts of the 1979 investigations conducted by Leech for the Geological Survey of Western Australia (GSWA), and was refi ned and conf irmed by other i nformation available. The area to t he west of the D e Grey R iver was in cluded in t he P roject a rea wit h in formation r egarding li thologies a nd wa ter levels b ased o n l imited i nformation a vailable from the D oW W IN datab ase and geo physical interpretations made by Rowston (1976). It i s acknowledged that significant uncertainty exists in this area. The conceptual hydrogeology described in this report repres ents a si mplified understan ding of the behavi our and dynami cs of the aqui fer system s and provi des the techni cal foundati on for the numerical model design and fram ework. A quifer parameter estimates have been provided for the aquifers and aquitard, however these parameters are initial estimates and will be refined during calibration of the numerical model. As previ ously menti oned, the West Canni ng Bas in contai ns t wo mai n aq uifer system s: th e unconfined Broome S andstone a quifer and th e deeper, l argely confi ned and arte sian Wal lal Sandstone aquifer (which includes the Alexander Formation). These two aqu ifers are separated by the generally impermeable Jarlemai Siltstone.

4.2 BROOME SANDSTONE (UNCONFINED AQUIFER) 4.2.1 AQUIFER PROPERTIES The unconfined Broome Sandstone is present over the West Canning Basin ranging in thickness from 10m i n the south to 130m in the northeast of the basin. Fi gure 4.1 presents the i nferred thickness of the Broome Sandstone over the Project area. Hydraulic tests were con ducted on fi ve bores compl eted i n the Broome Sandstone during th e 1979 i nvestigations (Lee ch, 1979). Measured hy draulic conducti vities ranged between 3 an d 15m/day, an d averag ed 7.5m/day. Specific yi eld val ues for the Broome S andstone ha ve not been calculated, however a sp ecific yiel d betwe en 10% and 30% has been estimated ( Leech, 1979). A hydrauli c conducti vity of 7. 5m/day has be en a dopted for t he Broome Sandstone f or thi s Project, based on the fi ndings of Leech (1979 ). A n initial specific yield value of 15% has been adopted for thi s Proj ect, and i s based on val ues typi cal for sediments such as the Broom e Sandstone. The Br oome Sa ndstone is o verlain b y r ecent s uperficial s ediments, s uch a s a lluvium, e olian deposits and sand dune s, across the basin approximately 5m thi ck. In the west of the P roject area, around the De Grey River, alluvium associated with the De Grey River reaches thicknesses up to 80m. The Broome Sandstone appears to pinch out in places to the west near the De Grey River, where i t i s thought to have been erod ed b y the pal aeo D e Grey River. D ue to l ack of information in the area west of the De Grey Ri ver, and for the purpo ses of the mo del, it ha s been i nferred that the B roome Sandstone fl attens out wi th limited vari ation i n th ickness an d depth. Where sup erficial sedi ments overl ie the Broome S andstone, th ese uni ts have been as signed a similar s pecific y ield ( 15%) a nd a hyd raulic c onductivity of 1m/day. Th ese param eters are based on our experi ence and knowl edge i n the ar ea and typical va lues fo r such sediments . However, over the major ity of the Project area, t he superfi cial sedi ments are expecte d to be largely unsaturated with the exception of the De Grey River area. 4.2.2 RECHARGE Recharge to the Broome Sandstone i s by di rect percolation of rai nfall (or i ndirectly through overlying sedi ments). O bservations have shown that the w ater tabl e fluctuates sea sonally, rising after sustained intense rainfall events (i.e. tropical cyclones) and declining during periods of reduced rainfall.

Our Reference 1033/B/021c Page 19

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

Rates of recharge to the unconfined Broome Sandstone aquifer were estimated by Leech (1979) as 6% of rai nfall. Thi s recharge calculation was based on an assumed porosity of 30% (base d on typical porosity values for si milar sediments) and changes i n water l evels following a large rainfall event (such as a c yclone). Whil e we feel that a val ue of 6% may be applicable to hi gh intensity rainfall events, when applied to average rainfall this number is likely to be significantly lower. We feel that a value of 3% may be more realistic, however, the rainfall recharge rate will be refined during calibration of the numerical model. Groundwater throughfl ow has bee n esti mated by Le ech (197 9) to be a pproximately 20x106 m3/yr (20GL/yr), based on a hydraulic conductivity of 7.5m/day. 4.2.3 GROUNDWATER FLOW There is l imited c urrent in formation a vailable r egarding dep ths t o wa ter in t he B roome Sandstone. However, based on the i nformation available (five GSWA bores) and work done by Leech (1 979), it is apparent that groundwater flow in the unconfi ned Broome S andstone i s generally i n a northerl y di rection, w ith groundwat er di scharge to the oc ean. In addi tion to groundwater di scharge to the ocean, potenti al exists for g roundwater di scharge throu gh seepage and evapotranspiration along the coastal strip where depths to water are less than 3m. In the western corner of the West Ca nning Basin, groundwater flow direction becomes no rth to north-westerly toward the De Grey River alluvium. The Broome Sandstone is unsaturated in the south of the basi n, where the b ase of the Br oome Sandstone is elevated. Figure 4. 2 presents wate r tabl e contours of the unconfi ned Broome S andstone and al luvium aquifer across the West Canning Basin.

4.3 JARLEMAI SILTSTONE (AQUITARD) The Jarl emai Sil tstone i s present over most of the West Canni ng Bas in, however the uni t shallows and thi ns to the south, eventuall y pinching out towards the souther n basin boundary. The Jarl emai Si ltstone re aches a thi ckness of up to 200m i n the northeast area of the basin. Figure 4.3 presents the i nferred extent and thi ckness of the Jarl emai Siltstone across the West Canning Basin. The Jarlemai Siltstone appears to pinch out in places to the west near the D e Grey River, where it is thought to have been eroded by recent alluvium. Du e to lack of information in the area west of the D e Grey Ri ver, and for the purpose s of the model , it has been i nferred that the Jarlemai Siltstone flattens out with limited variation in thickness and depth (Figure 4.3). This un it se parates the flow systems of the underlying conf ined Wal lal Sandstone from the overlying unconfined Broome Sandstone. Gi ven that groundwater movement i n each aqui fer is separate and di ffers markedl y in di rection and that there exi sts up to 30 m head di fference between the uni ts, the Jarl emai Sil tstone i s consi dered a si gnificant aqui tard. Ther efore, a horizontal hydraulic conductivity of 1x10 -3 m/day and a vertical hydraulic conductivity of 1x10 -4 m/day have been ad opted for thi s aquitard unit. The unconfined specific yield of the Jarl emai Siltstone has been estimated at 3.5%, based on the observed clayey nature of the unit.

Page 20 Our Reference 1033/B/021c

LOCATION MAP 117700

161600

115500

E E E

E E E

E E E E E E

E E E

E E E

E E E

E E E E E E

E E E E E E

E E E

m m m

m m m

m m m m m m

m m m

m m m

m m m

m m m m m m

m m m m m m

m m m

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 11 0 0 0 114400 0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

5 5 5 0 0 0 Legend

5 5 5 0 0 0 5 5 5 0 0 0

5 5 5 0 0 0 5 5 5

5 0 0 0 5 5

2 2 2

2 2 2 1 1 1

1 1 1 2 2 2 2 2 2 1 1 1

1 1 1 2 2 2 1 1 1

1 1 1 2 2 2 113300 Broome Sandstone Approximate Thickness (m) 77885500000000mmNN 112200 Project Area

Bore Location 111100 111100 Broome Sandstone Thickness (m) 110000

9900

9595 8800 --- 9595

77 --- 77880 7700 --- 77880000000000 mNmNmN 7373---

6600 5555 5656 7373 BroomeBroome SandstoneSandstone transitionstransitions 7272 7373 intointointo DeDeDe GreyGreyGrey alluvialsalluvialsalluvials intointointo DeDeDe GreyGreyGrey alluvialsalluvialsalluvials 4343 --- 5500 4343 4141 --- 00 00 3030 00 00 00 00 3939 4040 4040 4545 3636 2121 11 2121 5757 1100 3636 4400 2727 5757 2424 111 111 111 33 333 33 333 3300 000 3333 333 00 00 000 3333 00 00 000 3333 000 111 000 00 88111 000 00 88 000 2 2 2 4040 000 2 2 2 4040 000 2 2 2 4040 3030 0 0 0 1010 5151 NPNP0 0 0 1010 5151 NPNP0 0 0 1010 2323 5151 5353 2323 2200 1919 41374137 1212 00 41374137 111 1010 77775500000000 mNmNmN 000 4040 1010 FIGURE 4.1 3838 1515 Broome Sandstone Thickness (m)

--- AUTHOR: KMH REPORT NO: 021c DRAWN: SHC REVISION: c DATE: 5 March 2009 SCALE: 1:1,000,000 JOB NO: 1033B PROJECTION: MGA94 Location: F:\Jobs\1033\MapInfo\021c_fig4.1.WOR Z50/51

021 c MGA94 (Z51) 1:1,000,000 PROJECTION: REPORT NO: REVISION: SCALE: GSWA Bores Broome Water Levels (mRL) DoW WIN Database Water Levels (mRL) Alluvium/Broome Water Level Contours (mRL) Project Area Groundwater Flow Direction KMH KMH 23/04/2009 1033B Legend LOCATION MAP AUTHOR: DRAWN: DATE: JOB NO: FIGURE 4.2 Alluvium/Broome Sandstone Water Levels 4 4 4 5 5 5 4 4 4 5 5 5 6. 6. 6. 6. 6. 6. 6. 6. 6. 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7

N N N

N N N N N N

N N N N N N

N N N 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5

m m m

m m m m m m

N N N m m m m m m

N N N

m m m

N N N

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 8.2 8.2 8.2 - - -

0 0 0 8.2 8.2 8.2 - - -

m m m 8.2 8.2 8.2 - - -

m 0 0 0 m m

0 0 0 m m m

6.38 6.38 6.38 0 0 0

0 0 0 0 6.38 6.38 6.38 0 0 6.38 6.38 6.38 0 0 0

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0 0 0 0 - - -

0 0 0 0 0 0

- - - 0 0 0

0 0 0 0 - - - 0 0

0 0 0

0 0 0

0 5 5 5 0 0

5 5 5 0 0 0 0 0 0

5 5 5 0 0 0

0 0 0

0 0 0

0 8 8 8 0 0

8 8 8 0 0 0 8 8 8

8 8 8

8 8 8

8 8 8

5 5 5

5 7 7 7 5 5

7 7 7 5 5 5 7 7 7

7 7 7

7 7 7 8.7 8.7 8.7

7 7 7 8.7 8.7 8.7

7 7 7 8.7 8.7 8.7

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

8.1 8.1 8.1

8.1 8.1 8.1

8.1 8.1 8.1

E E2 E2 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 5 5 5 2 E E E 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 5 5 5 2 2 2 E E2 E2 0 m 0 m 0 m 0 0 0 0 0 0 0 0 0 5 5 5 2 0 0 0 0 0 0 - - - 0 0 0 ------

3.62 3.62 3.62 3.62 3.62 3.62 3.62 3.62 3.62

------

E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 Dry Dry Dry 0 0 0 ------7.82 7.82 7.82 Dry Dry Dry 0 0 0 ------7.82 7.82 7.82 Dry Dry Dry Dry Dry Dry 0 0 0 ------7.82 7.82 7.82 Dry Dry Dry Dry Dry Dry

2.95 2.95 2.95

2.95 2.95 2.95 2.95 2.95 2.95

0 0 0

0 0 0 0 0 0

3 3 3

3

3 3

3 3 3

0 0 0

0 0 0 0 0 0

2 2 2

2 2 2 2 2 2

000

000

5 5 5

5 5 5

5 5 5

0 0 0

0

0 0

0 0 0

1 1 1

1

1 1

1 1 1

mE mE mE 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 1 1 1 mE mE 0 mE 0 0 0 0 0 0 0 0 0 0 0 5 5 1 5 1 1 mE mE mE 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 1 1 1 18.26 18.26 18.26 18.26 18.26 18.26 18.26 18.26 18.26 30.44 30.44 30.44 30.44 30.44 30.44 11.61 11.61 11.61 30.44 30.44 30.44 11.61 11.61 11.61 11.61 11.61 11.61 11.05 11.05 11.05 11.05 11.05 11.05 11.05 11.05 11.05 15.35 15.35 15.35 15.35 15.35 15.35 15.35 15.35 15.35 ------2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 28.15 28.15 28.15 28.15 28.15 28.15 28.15 28.15 28.15 12.4 12.4 12.4 12.4 12.4 12.4 12.4 12.4 12.4 19.35 19.35 19.35 13.6 13.6 13.6 19.35 19.35 19.35 13.6 13.6 13.6 19.35 19.35 19.35 13.6 13.6 13.6 15.75 15.75 15.75 15.75 15.75 15.75 15.75 15.75 15.75 16.5 16.5 16.5 16.5 16.5 16.5 - - - 16.5 16.5 16.5 ------10.8 10.8 10.8 10.8 10.8 10.8 10.8 10.8 10.8 29.77 29.77 29.77 29.77 29.77 29.77 29.77 29.77 29.77 9.6 9.6 9.6 9.6 9.6 9.6 9.6 9.6 9.6 11.94 11.94 11.94 11.94 11.94 11.94 11.94 11.94 11.94

24.82 24.82 24.82

24.82 24.82 24.82

9.09 9.09 9.09

24.82 24.82 24.82

9.09 9.09 9.09

9.09 9.09 9.09

E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 E E E m m m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 7 7 7 7 7 7 7 7 7 17.67 17.67 17.67 17.67 17.67 17.67 32.11 32.11 32.11 17.67 17.67 17.67 32.11 32.11 32.11 32.11 32.11 32.11 44.31 44.31 44.31 44.41 44.41 44.41 44.31 44.31 44.31 44.41 44.41 44.41 44.31 44.31 44.31 44.41 44.41 44.41 37.33 37.33 37.33 37.33 37.33 37.33 37.33 37.33 37.33 23.84 23.84 23.84 23.84 23.84 23.84 23.84 23.84 23.84 ------10.81 10.81 10.81 10.81 10.81 10.81 10.81 10.81 10.81 Location: F:\Jobs\1033B\MapInfo\021c_fig4.2.WOR

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

4.4 WALLAL SANDSTONE (CONFINED AQUIFER) 4.4.1 AQUIFER PROPERTIES The Wallal Sandstone is an extensive unit and is present over the entire West Canning Basin. It is confi ned by the Jarl emai Siltstone a cross most of the basi n, except i n the south where th e base of the Jarlemai Sil tstone ri ses above water tabl e, and at the sou thern basi n bo undary where the Jarl emai Sil tstone i s absent and the Wa llal Sandston e i s in di rect contact wi th the unsaturated Broome Sandstone. As previously mentioned, the Wal lal Sandstone can be divided into an upper finer grained unit (Alexander Formation) and a coarser, more permeable lower unit. Available data suggests that Leech (1979) i ncluded the A lexander Formati on withi n the Wal lal S andstone uni t. Tabl e 4. 1 shows a compari son between uni t depths and thi cknesses at GS WA bore 10A (logged by Lee ch (1979)) and the nearby p roduction bore dri lled at Pardoo stati on (Aquaterra, 2009). A vailable lithological data from pet roleum wells drilled within the Project area differentiates between the Alexander Formation and the l ower Wallal Sandstone. There a re no known aqui fer parameters established for the A lexander Formation. Revi ew of available data suggests that the A lexander Formation is generally one-third to one-quarter of the overall Wallal Sandstone thickness across the basin. F or the purposes of thi s Project, the Alexander Formation is represented as part of the W allal a quifer a nd h as b een a ssigned t he s ame in itial a quifer p arameters a s t he o verall Wallal aquifer, which are discussed further below.

Table 4.1: Summary of Lithology at GSWA10A and Pardoo

Unit Unit Depths (mRL) GSWA10A Pardoo PB1

Broome Sandstone 21 21 Jarlemai Siltstone 0 2 Alexander Formation -17 -20 Wallal Sandstone -35

The Wallal aquifer is artesian along the coastal plain where the measured potentiometric surface reaches up to 30m above sea level. Figure 4.4 shows where the Wallal Sandstone is unconfined and where the aquifer becomes artesian. The Wal lal Sandstone ran ges i n thi ckness from 14 m to 355m i n the study area. Fi gure 4. 5 presents the inferred thickness of the Wallal Sandstone over the Project area. In addition, the Wallal Sandstone appears to pi nch out, al ong with the Bro ome Sandstone and Jarlemai Siltstone, in places to the west near th e De Grey Ri ver, where i t is thought that these units have b een eroded out by recent all uvium. Due to lack of information in the area west of the D e Grey Ri ver, and for the purposes of th e mo del, it h as b een in ferred t hat t he Wallal Sandstone flattens out with limited variation in thickness and depth (Figure 4.5). Hydraulic tests were conducted on 1 8 sub-artesian and artesi an bores com pleted in the W allal Sandstone during the 19 79 investigation (Leech, 1979). Th e resulting test pumpi ng data was matched with leaky artesian type curves. Measured hydraulic conductivities range from 1m/day to 138m/day (Leech, 1979), however bore constru ction of the GSWA bores did not scree n the entire length of the Wallal Sandstone aquifer and typically only represented an average of 18m sections of the aquifer. Therefore, these calculated mean hydraulic conductivity values may not be representative of the entire Wallal Sandstone unit. More recent investigations by Moly Mines and A tlas Iron cal culated hydrauli c conducti vity val ues around 40-4 5m/day (Aquaterra, 2007 ) and 20-60m/day (Aquaterra, 2009), respectively. A uniform hydraulic conductivity of 20m/day was adopted by Leech (1979) and is considered appropriate as an initial estimate.

Our Reference 1033/B/021c Page 25

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

The aeri al distri bution of hydraul ic c onductivity for the Wal lal Sandstone i n the Projec t area suggests a decrea sing hydrauli c co nductivity tr end i n a westerl y di rection and a slight decreasing trend in a northerly direction toward the ocean (Figure 4.6). This decreasing trend is in line w ith our unders tanding of the Wal lal Sandstone, whi ch was deposi ted i n a fl uvial environment in the Canning Basin. A confi ned storage co efficient of 5x10 -4 has be en adopt ed for the Wal lal Sandstone a quifer, based on an alysis by Leech (1979), M oly M ines (Aquaterra, 20 07) and A tlas Iron (A quaterra, 2009). Whe re the Wal lal i s unconfi ned, a speci fic yield of 20% has been a pplied, consistent with typical values for clean sand/gravel aquifers. 4.4.2 RECHARGE The dominant source of r echarge to t he Wallal Sandstone in the study area i s via throughflow from outsi de the model area. A small percentage of recharge wil l al so be deri ved from infiltration of rai nfall during i ntense events along the southern margin of the basi n, where th e Jarlemai Siltstone is absent and the Wallal Sandstone is unconfined (Figure 4.4). This rainfall recharge val ue wi ll be appl ied cons istent wi th the Broome Sandstone r echarge val ue, in calibration of the numerical model. Groundwater throughflow at the eastern margin of the West Canning Basin has been estimated by Leech (1979) to be approximately 21x106 m3/yr (21GL/yr), based on a hydraulic conductivity of 20m/day. 4.4.3 GROUNDWATER FLOW Groundwater flow direction in the Wallal Sandstone i n the l arger Canning Basin is in a general northerly direction (Leech, 1979). Whereas, groundwater flow in the Project area is in a general west-northwesterly di rection, due to t he radi al di stribution of the fl ow from the l arger basi n. Figure 4.7 presents the potentiometric surface of the Wal lal Sandstone across the Projec t area. Groundwater di scharge from the Wal lal aquifer o ccurs offshore al ong preferenti al flow paths associated with faul ting and/or by upward l eakage, given the pressure di fferential between th e Wallal Sandstone and the Broome Sandstone. The h ydraulic g radient in t he W allal Sandstone is r elatively u niform a cross t he s tudy area, despite possible reducti ons i n hydraulic conducti vity towards th e west (Figure 4. 6 an d 4.7). This indicates potential for groundwater loss from the Wallal aquifer through upward leakage in the west of the Project area.

4.5 SPRINGS It has been s uggested that the spri ngs present along the coast i n the Project area are so urced from minor upward leakage from the Wallal Sandstone. However, one of t he springs, Myadee Spring, has been dry for some years whil st artesian heads i n the Wallal Sandstone in this are a are around 10m above ground level. It i s underst ood that the DoW wi ll be col lecting water sam ples from a num ber of spri ngs a nd shallow bores l ocated al ong the coast i n the West Canni ng Basi n in May 2009. Thes e water samples will be anal ysed for major ions, trace metal s and Carbon-14 dating. Thi s data will assist in d etermining t he s ource of th e s prings, but wil l n ot b e a vailable fo r in clusion in t his Project as currently defined. These springs are not tho ught to comprise a significant part of the overall water balance of the West Canning Basin and the origin of the water i s not yet known wi th any degree of certai nty. The spri ngs and thei r mechani sm of d ischarge w ill be repre sented by evapotranspi ration (ET) from the Broome aquifer, or superficial sediments, in the numerical model developed within the scope of this Project.

Page 26 Our Reference 1033/B/021c

021c c MGA94 Z50/51 1:1,000,000 PROJECTION: REPORT NO: REVISION: SCALE: Bores Jarlemai Siltstone Thickness (m) Jarlemai Siltstone Approximate Thickness (m) Project Area 6 March 2009 KMH SHC 1003B Legend LOCATION MAP AUTHOR: DRAWN: DATE: JOB NO: FIGURE 4.3 Jarlemai Siltstone Thickness (m)

000 99 000 99 000 19 888 19 888 111 111 ------

000

E E E 0 m 00 m m

0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 2 2 2 128 128 128 E E E m m m

0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 2 2 128 128 128 2 E E E m m m

0 0 0 0 0 0 0 0 000 0 0 0 0 000 5 5 5 128 128 128 2 2 000 2 000 777 111 777 111 - - - 777 - - -

00 - - - 111 00 - - 11 - 11

1 - - 000 - 11 111 000 000 - - - 11 444 000 11 111444 333 111 111

000 000 111 111 000 666 111 000 000 000

999 999 999

000 000 888 888

000 000 000

555

555

555

0 0 0

0 0 0

0 0 0

24 18 24 18 24 18

0 0

0 24 18 24 18 24 18

0 0 0

7 7 7 24 18 24 18 24 18

0 0 0

7 7 7

7 7 7

6 6 6

6 6 6

6 6 000 6 222 NP NP NP

111 NP NP NP 111 NP NP NP 24 24 24 24 24 24 26 26 26 24 24 24 24 24 24 26 26 26 NP NP NP 24 24 24 24 24 24 26 26 26 NP NP NP

NP NP NP

40 40 40

40 40 40

40 40 40 95 95 95 95 95 95 74 74 74 43 43 43 95 95 95 000 74 74 74 43 43 43 000 74 74 74 43 43 43

000 000 NP NP NP

NP NP NP 111 NP NP NP

E E E

m

m

m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 E 2 2 2 E E

m

m

m 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 2 0 2 2 E E E

m

m

m 000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 000

111111

0 0 0

0 0 000 0

0 0 000 0 69 69 69 69 69 69

69 69 69 69 69 69

999 51 51 51 28 28 28 15 15 15

69 69 69 69 69 69

3 3 999 51 51 51 28 28 3 28 15 15 15

3 3 999 51 51 51 28 28 28 3 15 15 15

3 3 3

0 0 0

0 0 0

0 0 0

2 2 2

2 2 2

2 2 2

0 0 0

0 0 0

0 0 0 64 64 64 64 64 64

000 64 64 64 000 46 46 46 40 40 40 40 000 46 46 46 40 40 40 40 40 888 46 46 46

000 777 000 111 30 30 30 30 30 30 49 49 49 46 46 46 15 15 15 30 30 30 49 49 49 46 46 46 15 15 15 14 14 14 49 49 49 46 46 46 15 15 15 14 14 14 14 14 14

000

000

666

666 20 20 20

666 20 20 20 26 26 26 E E E 20 20 20 m m m

0 0 0 0 0 0 26 26 26 0 0 0 0 0 0 E 5 5 E 5 E 1 1 1 m m

m

0

0 0 0 0 0 26 26 26 0 0 0 0 0 5 0 5 E 5 E E 1 1 1 m m m

0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 1 1 1 40 40 40 40 40 40 40 40 40

0 0 0

0 0 0

0 0 0

5 5 5

5 5 5

5 5 5 NP NP NP NP NP NP NP NP NP 36 36 36 36 36 36 36 36 36 15 15 15 15 15 15 15 15 15 NP NP NP NP NP NP 19 19 19 NP NP NP 19 19 19 19 19 19 8 8 8 8 8 8 8 8 8 000 444 NP NP NP NP NP NP 20 20 20 NP NP NP 20 20 20 20 20 20 303030 0 0 0 0 0 0 0 0 0 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5

0 0 0

0 0 0

0 0 0

1 1 1

1 1 1

1 1 1

E E E m m m 0 0

0 0 0 0 0 0 0 E 0 0 E 0 E 0 0 0 m 5 5 5 m m 1 1 1 0 0 0 0 0 0 0 0 0 0 0 E 0 E E 0 0 0 5 5 5 m m 1 m 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 5 5 1 1 1 N N N

N N N

N N N

N N N

N N N 0 0 0 N N N 0 0 0 0 0 0

N N N

N N N

N N N

m m m m m m

m m m m m m

m m m m m m

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

m m m

m m m

m m m

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0

0 0 0

0 0 0

5 5 5 0 0 0

5 5 5 0 0 0

5 5 5 0 0 0

0 0 0

0 0 0

0 0 0

8 8 8 8 8 8

8 8 8 8 8 8

8 8 8 8 8 8

5 5 5

5 5 5

5 5 5

7 7 7 7 7 7

7 7 7 7 7 7

7 7 7 7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7

7 7 7 Location: F:\Jobs\1033\MapInfo\021c_fig4.3.WOR

LOCATION MAP

Legend

Project Area

Wallal Sandstone Unconfined Area

Wallal Sandstone Artesian Boundary

GSWA Bores Water Level (mRL)

41.9941.9941.99 38.7438.7438.74 37.17-37.17-37.17- 27.727.727.7 37.17-37.17-37.17- WallalWallal ArtesianArtesian 43.6443.6443.64 43.6443.6443.64 45.9945.9945.99 31.2431.2431.24 19.2219.2219.22 38.2238.2238.22 22.222.222.2 25.7425.7425.74 22.222.222.2 25.7425.7425.74 29.7629.7629.76 --- 11.1811.1811.18 29.7629.7629.76 --- 46.646.646.6 9.879.879.87 ------25.7825.7825.78 30.1730.1730.17 43.8643.8643.86 9.969.969.96 25.7825.7825.78 38.0138.0138.01 43.8643.8643.86 --- 38.0138.0138.01

30.8130.8130.81

45.645.645.6 FIGURE 4.4 Wallal Sandstone Unconfined & Artesian Heads Boundary

AUTHOR: KMH REPORT NO: 021 DRAWN: KMH REVISION: c DATE: 5/03/09 SCALE: 1:1,000,000 JOB NO: 1033B PROJECTION: GDA94 (Z51) Location: F:\Jobs\1033B\MapInfo\021c_fig4.4.WOR

LOCATION MAP

444 222 000

44 440000

380380380 Legend

Bores Wallal Sandstone Thickness (m)

Wallal Sanstone Approximate Thickness (m) 333 666 000 33 3322 333 000 3300 2200 444 Faults 0000 00 000 Project Area

22 8800 2266 00 6600 22 22 --- 357357 1188 220 2222 2244 --- 8800 0000 00 00

333 666 1166 000 114400 6600 --- 339339 ---

112200

3 3 3 3 3 3 3 3 3

2 2 2 2 2 2 22 2 2 2 33 18918922 0 0 0 33 18918900 0 0 0 44 18918900 0 0 0 44 00 218218 00 00 101000 116116 11 1010 9898 116116 8800

222 333 115115 220220220 222808080333000 321321 115115 151151 808080 000000 321321 444 666 8282 111 000 438.54438.5666 84.584.5 58.558.5 8282 111666 22 000 000 84.5884.5800 58.558.5 666 66 000 8800 000 4242 89 000 22 6600 666000 8989 111 000 2244000 666 2121 444 00 2121 7272 111 000 7272 6262 107107 222 000 3535 6262 107107 104104222 104104000 2200 00 6262 22 00 6262 4400 666 11 00 1919 NPNP 4400 666000 1100 NPNP 2828 000 0000 6363 000 3636 888 9696 NPNP 5151 000 NPNP 22 2200 125132125132 125125 1414 125132125132 125125 109109 8686 109109 6969 102102 6969 8910289102 FIGURE 4.5 6060 Wallal Sandstone Thickness (m) --- AUTHOR: KMH REPORT NO: 021 DRAWN: SHC REVISION: c DATE: 6 March 2009 SCALE: 1:1,000,000 JOB NO: 1033B PROJECTION: MGA94 Z50/51 Location: F:\Jobs\1033\MapInfo\021c_fig.4.5.WOR

LOCATION MAP

LEGEND

Bores (Hydraulic Conductivity, K (m/day))

Project Area 100,000mE 100,000mE 100,000mE 100,000mE 100,000mE 100,000mE 100,000mE 100,000mE 100,000mE 250,000mE 250,000mE 250,000mE 250,000mE 250,000mE 250,000mE 250,000mE 250,000mE 250,000mE 150,000mE 150,000mE 150,000mE 150,000mE 150,000mE 150,000mE 200,000mE 200,000mE 200,000mE 150,000mE 150,000mE 150,000mE 200,000mE 200,000mE 200,000mE 200,000mE 200,000mE 200,000mE

7,800,000mN7,800,000mN

5.45.4 15.515.5 25C25C 0.60.6 5.95.9 22A22A 9D9D 17A17B17A17B 1717 24.124.1 3.33.3 21A21A 24.124.1 3.33.3 21A21A 24A24A 1.61.6 8A8A 8A8A 9.79.7 138.3138.3138.3 4A4A --- 9.79.7 138.3138.3138.3 --- 6.56.5 16A16A 42.942.9 8.18.1 11A11A 10A10A 8.58.5 42.942.9 31.631.6 10A10A 7A7A 20C/D20C/D 31.631.6 --- 3A3A 7A7A 23A23A 2D2D 2D2D --- 5.45.4 --- 12A12A --- 5.45.4 33 ------12A12A 6A6A --- 1A1A --- 14A14A 15A15A 19A19A 13A13A 15A15A 4040 --- 4040 4545 --- MMCA01PMMCA01P MMCA13PMMCA13P 5A5A MMCA13PMMCA13P --- 7,750,000mN7,750,000mN 18A18A FIGURE 4.6 Wallal Sandstone Hydraulic Conductivity Distribution

AUTHOR: KMH REPORT NO: 021 DRAWN: KMH REVISION: c DATE: 9/03/09 SCALE: 1:900,000 JOB NO: 1033B PROJECTION: MGA94 (Z50/51) Location: F:\Jobs\1033B\MapInfo\021b_fig4.6.WOR

LOCATION MAP

Legend Wallal Sandstone Water Level Contours (mRL)

Project Area

Groundwater Flow Direction

000 111 Wallal Sandstone Unconfined Area

Wallal Sandstone

000 Artesian Head Boundary 333 000 222

000 555 41.9941.9941.99 38.7438.7438.74 27.727.727.7 37.17-37.17-37.17- 27.727.727.7 Wallal Artesian 000 444 43.6443.6443.64 444 43.6443.6443.64 45.9945.9945.99 31.2431.2431.24 19.2219.2219.22 38.2238.2238.22 22.222.222.2 25.7425.7425.74 25.7425.7425.74 29.7629.7629.76 --- 11.1811.1811.18 29.7629.7629.76 --- 46.646.646.6 9.879.879.87 ------30.1730.1730.17 9.969.969.96 25.7825.7825.78 38.0138.0138.01 43.8643.8643.86 000 --- 38.0138.0138.01 666

30.8130.8130.81

000 45.645.645.6 777 FIGURE 4.7 Wallal Sandstone Potentiometric Surface 000 888 AUTHOR: KMH REPORT NO: 021 000 999 DRAWN: KMH REVISION: c DATE: 5/03/09 SCALE: 1:1,000,000 JOB NO: 1033B PROJECTION: GDA94 (Z51) Location: F:\Jobs\1033B\MapInfo\021c_fig4.7.WOR

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

4.6 HYDROCHEMISTRY 4.6.1 BROOME SANDSTONE Investigations by Leech (1979) indicate that groundwater salinity in the Broome S andstone and other unconfined aquifers in the Project area range from 380mg/L total dissolved solids (TDS) in the east to over 10, 000mg/L TDS in the west of the Proje ct area. El evated groundwater salinities in the west of the study area are thou ght to be due to evapotranspi ration in low lying coastal areas, where the depth to water is less than 5m below ground level. Spatial distribution of groundwa ter sal inity in the Broo me S andstone was pre sented by L eech (19 79) and i s provided in Appendix A. Figure 4.8 is an expanded Durov diagram showing groundwater in the Broome S andstone to be chloride and sodi um do minant, indicative of mature groun dwater or evapotranspiration processes. 4.6.2 WALLAL SANDSTONE Groundwater salinity values in the confined Wallal Sandstone aquifer were measured during the 1979 investigation by Leech and range from around 250mg/L TDS in the ea st to approximately 2,000mg/L TDS in the west of the Project area. Two parti cularly hi gh concentrati ons are reported (5,500mg/L and 13,700mg/L). It is not clear if these elevated salinities are associated with the Wallal aquifer. G iven the large hydraulic heads in the Wallal aquifer at the coast, the increase in groundwater salinity in the west of the Project area is unlikely to be due to sali ne intrusion. Rather, it may be due to mixing or intrusion of higher salinity water associated with basement or structural changes at the western boundary of the basin. The aerial distribution of groundwater salinity in the Wallal Sandstone was presented by Leech (1979) and is provided in Appendix A. The DoW collected a number of water samples from selected GSWA bores i n the north of the West Canni ng Basi n in Decemb er 200 8. These water sampl es were anal ysed for major i ons, trace metals and Carbon-14 dating (refer Table 4.2 and 4.3). Figure 4.8 is an expanded Durov diagram, showing groundwater in the Wallal Sandstone to vary from sul phate domi nant and sodi um domi nant, w hich is indi cative of m ixing i nfluences, to chloride and sodium dominant, i ndicative of “end point” or mature groundw ater. Thi s is to b e expected given the di stance of the sample po ints from the recharge a rea for the Wallal Sandstone. 4.6.3 SPRINGS Salinities of the spri ngs ranged from 1, 000mg/L to 3, 200mg/L TD S, however these higher salinities may be due to localised salt concentration from evapotranspiration. Figure 4.8 is an expande d Durov diagram showing the spri ng water to be chl oride and sodi um dominant. Concentrations of ni trate and bicarbonate, c ommon i ndicators of r ecent recha rge to groundwater, are low in the spring water analysed and more consistent with Wallal groundwater than that from the Broome S andstone. However, concentrations of cal cium and magnesi um in the spring water are more similar to the shal low groundwater sample than to the sampl es from the Wallal aquifer.

Our Reference 1033/B/021c Page 37

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

Table 4.2: Summary of Field Water Quality Analysis (DoW, 2009)

Bore ID Sample Date Temp (°C) Electrical Dissolved pH DO % Sat Redox Titration Comments Conductivity Oxygen Potential (100mL) Drops

(mS/cm) (mg/L) (ORP) (mV) (1.6N H2SO4)

PB1 2/12/08 33.47 0.600 6.71 6.46 94.7 180 83 C14 sample not filtered rest filtered via syringe PB3 2/12/08 33.58 0.359 6.54 6.19 91.7 193 52 WCB22 3/12/08 32.90 1.020 0.77 6.39 11.2 -24 171 WCB17 3/12/08 34.21 0.801 0.43 6.52 5.5 18 203 WCB9 3/12/08 32.49 1.670 0.21 6.23 2.9 -5 46 WCB8 3/12/08 32.81 1.700 0.68 6.27 9.4 -130 126 Data logger in bore

WCB4 4/12/08 32.41 3.040 1.18 6.17 14.3 101 47 WCB10 4/12/08 31.90 2.000 0.34 6.32 4.4 76 63 C14 sample not filtered rest filtered via syringe as bore flow pressure is too low for online filter to be used:

Page 38 Our Reference 1033/B/021c

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

Table 4.3: Summary of Laboratory Water Quality Analysis (DoW, 2009).

Analyte LOR Units PB1 PB3 WCB22 WCB17 WCB17 WCB9 WCB8 WCB4 WCB10 Date 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 Collected

Aluminium mg/L <0.005 <0.005 <0.005 <0.005 - <0.005 <0.005 <0.005 <0.005 Barium mg/L 0.11 0.097 0.035 0.034 - 0.082 0.04 0.046 0.049 Beryllium mg/L <0.001 <0.001 <0.001 <0.001 - <0.001 <0.001 <0.001 <0.001 Boron mg/L 0.11 0.1 0.15 0.24 - 0.13 0.17 0.17 0.16 Chromium mg/L 0.002 0.003 <0.001 0.003 - <0.001 <0.001 <0.001 0.002 Cobalt mg/L <0.001 <0.001 <0.001 <0.001 - 0.002 0.003 <0.001 <0.001 Copper mg/L 0.001 0.006 <0.001 0.001 - <0.001 0.001 0.003 0.001 Lead mg/L <0.001 0.002 0.002 <0.001 - <0.001 <0.001 <0.001 <0.001 Lithium mg/L <0.001 <0.001 0.021 0.006 - 0.008 0.004 0.019 <0.001 Molybdenum mg/L <0.001 <0.001 <0.001 0.002 - <0.001 <0.001 <0.001 <0.001 Nickel mg/L <0.001 <0.001 <0.001 0.003 - 0.005 0.004 0.002 0.002 Strontium mg/L 0.29 0.21 0.36 0.24 - 0.72 0.68 1.2 0.81 Thorium mg/L <0.001 <0.001 <0.001 <0.001 - <0.001 <0.001 <0.001 <0.001 Titanium mg/L <0.005 <0.005 <0.005 <0.005 - <0.005 <0.005 <0.005 <0.005

Uranium mg/L <0.001 <0.001 <0.001 <0.001 - <0.001 0.003 <0.001 <0.001 Vanadium mg/L <0.001 <0.001 <0.001 <0.001 - <0.001 <0.001 <0.001 <0.001 Zinc mg/L 0.025 0.092 0.037 0.11 - 0.046 0.054 0.037 0.1 Bromide <0.01 mg/L 0.45 0.24 0.75 0.58 0.61 0.96 1.6 1.4 1.4 Calcium - <1 mg/L 21 15 30 20 20 64 61 86 68 Filterable

Chloride <10 mg/L 110 60 170 140 140 450 380 760 500

Our Reference 1033/B/021c Page 39

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

Analyte LOR Units PB1 PB3 WCB22 WCB17 WCB17 WCB9 WCB8 WCB4 WCB10 Date 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 2-Dec-08 Collected Fluoride <0.05 mg/L 0.2 0.2 0.4 0.5 0.5 0.3 0.3 0.2 0.2 Iodide <0.05 mg/L <0.05 <0.05 0.24 0.23 0.23 0.08 0.19 0.11 0.12

Magnesium <1 mg/L 14 9 14 11 11 32 31 45 34 - Filterable Nitrate as <0.010 mg/L 5.7 1.7 0.037 <0.010 <0.010 <0.010 <0.010 <0.010 0.01 NO3-N (Calc)

FRP as P <0.005 mg/L 0.006 0.009 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Potassium - <1 mg/L 5 3 8 6 7 10 11 18 10 Filterable Silica as <0.002 mg/L 61 58 16 16 16 14 17 14 21 SiO2

Sodium - <10 mg/L 70 40 160 150 150 210 230 430 270 Filterable Sulfate <5 mg/L 15 <5 92 73 72 77 160 230 140

Iron - <0.005 mg/L 0.007 <0.005 1.8 0.15 0.16 0.87 0.012 0.2 0.033 Filterable Manganese <0.001 mg/L <0.001 <0.001 0.019 0.006 0.006 0.017 <0.001 0.071 0.003 - Filterable

Page 40 Our Reference 1033/B/021c

2+ Mg 50% WATER TYPE SUB-FIELDS - 2+ Broome 1. HCO3 and Ca dominant (frequently indicates recharging waters) - 2+ 2. HCO3 dominant and Mg dominant or cations indiscriminant - + 3. HCO3 and Na dominant (ion exchanged waters) 2- 2+ Wallal Ca2+ 25% Na+ 25% 4. SO4 dominant or anions indiscriminant and Ca dominant (recharge/mixed water) Mg2+ 25% Mg2+ 25% 5. No dominant anion or cation (dissolution/mixing) 2- + 6. SO4 dominant or anions indiscriminant and Na dominant (mixing influences) 7. Cl- and Ca2+ dominant (cement pollution or reverse ion exchange of NaCl waters) Springs 8. Cl- dominant and no dominant cation (reverse ion exchange of NaCl waters) 9. Cl- and Na+ dominant (end point water)

+ 2+ 2+ Na 50% 2+ Ca 25% Ca 25% TDS Ca 50% + + - Na 25% Na 25% 0 500 1000 1500 2000 2500 3000 3500 HCO3 50% 1. 2. 3. 25% 25% - 3 2- 4 SO HCO 25% - 3

25% 4. 5. 6. - Cl HCO 50% 2- 4 SO 25% - 3 25% -

Cl 7. 8. 9. HCO 25% 2- 25% - 4 Cl SO 50% - Cl

Expanded Durov Diagram Figure 4.8

Date: 11/03/09 Project: West Canning Basin Description: Conceptual Hydro HydroCHEM 2.0 F:\Operations\Staff Ops\techtools\[HydroCHEM2.0.xls]Project Information Project No: 1033B Client: Department of Water

WEST CANNING BASIN MODEL DESIGN REPORT CONCEPTUAL HYDROGEOLOGY

4.7 CONCEPTUAL MODEL The conceptual hydrogeology as descri bed in the preceding sections has be en summarised and presented i n Fi gure 4.9 and Fi gure 4.10. Fi gure 4. 9 r epresents our un derstanding of the hydrogeology i n the north-south di rection acro ss the mi ddle of the basi n, whilst Fi gure 4. 10 represents our understanding of the h ydrogeology in the western area, near the De Grey River, in an east-west direction. The general location of these sections is shown in Figure 4.11. The south-western margi n of the Project area has been assi gned approximately 20km west of the De Grey River. There is limited information available regarding the stratigraphy in the area around the De Grey Ri ver and, as m entioned, information available suggests that the Broome Sandstone h as be en ero ded out i n pl aces by th e palaeo D e Grey Ri ver, and that ther e exists hydraulic co nnection between the Broome Sandston e and the D e Grey Ri ver all uvials. The extent of the Broome Sandstone, Jarlemai Siltstone and Wallal Sandstone in this area has been estimated based on available information and knowledge in the area. Following t he d ata r eview, it is a pparent t here has b een limit ed h ydrogeological o r min eral exploration in the southeast area of t he West Canning Basin. A petroleum bore, Pandanus, was drilled to 214m i n the s outheast are a of the West Canni ng Basin, howe ver li thological and hydrogeological information could not be found for this bore. As there is no further information available i n this area, we have i nferred stra tigraphic depths, etc based on the rema ining information available. In addition, the elevation of the inflow boundary for the Wallal Sandstone in this area of the basin will be assigned during the calibration of the model, which will, inturn, confirm recharge to the Wallal Sandstone via throughflow from outside the model area. There are a number of fa ults within the Project area that ar e thought to be present within the basement ro ck (Figure 2.1 and 4. 5). There i s no i ndication, from the avai lable data set , tha t these faults influence the hydrogeol ogy of the Wal lal Sandstone, Jarlemai Siltstone or Bro ome Sandstone. In addi tion, there does not appear to be any correl ation between these faul ts and observed piezometry (Figure 4.7).

Our Reference 1033/B/021c Page 43

South North B' B Rainfall Recharge

Broome Aquifer Groundwater Flow Direction North-South (Broome Aquifer) Wallal Evapotranspiration WL

Broome WL Groundwater Inflow Jarlemai Aquitard Alexander Formation Groundwater Flow Direction North-westerly (Wallal Aquifer) Leakage

Wallal Aquifer Groundwater Outflow

Granite Dora Formation

Grant Formation

Granite, Dora Formation and Grant Formation are not anticipated to have any interaction with the Wallal aquifer

NOT TO SCALE

GENERALISED CONCEPTUAL HYDROGEOLOGY FIGURE 4.9

\\aquaterra.com.au\data\at1\Jobs\1033B\Reports\021c\021c Figs\[021c_FIG4.9.xls]Sheet1

West East

A A'

De Grey no 4 De Grey no 2 De Grey no 1 GSWA4A 40 Wallal Water Level 20

Unconfined 0 Water Level

Broome Sandstone -20 Alluvium

-40

-60 Jarlemai Siltstone

mAHD Alexander Formation -80

Leakage -100

-120 Wallal Sandstone

-140

-160 Basement

-180 0 5,000 10,000 15,000 20,000 25,000 30,000 Chainage (m)

GENERALISED CONCEPTUAL HYDROGEOLOGY IN THE WEST OF THE PROJECT AREA FIGURE 4.10

\\aquaterra.com.au\data\at1\Jobs\1033B\Reports\021c\021c Figs\[021c_Fig4.10.xls]Sheet1

LOCATION MAP

Legend Cross Section

Bore ID

Faults Project Area

WALLALWALLALBMRBMRBMR 04 04ARTESIA04AARTESI04A MandMand ManManAoodN

WALLALWALLAL NONO 11 KIMBERLEYKIMBERLEY ChirupChirup 11 SAMPHIRESAMPHIRE MARSHMARSH LLIII 7

B 25C25C 22A22A 25C25C 9D9D 17A17A A A' DeDe GreyGrey No1No1 21A21A 24A24A CorbettCorbett 11 8A8A DeDe GreyGrey No4No4 4A4A 8A8A DeDe GreyGrey No2No2 4A4A 16A16A DeDe GreyGrey No2No2 11A11A 10A10A 16A16A 11A11A 10A10A 20A20A 3A3A 7A7A 20A20A 23A23A DeDe GreyGrey No3No3 2D2D DeDe GreyGrey T2T2 12A12A 6A6A DeDe GreyGrey T1T1 1A1A 14A14A 6A6A 19A19A 1A1A 13A13A 15A15A MMCA01PMMCA01EMMCA01PMMCA01EMMCA13EMMCA13E 5A5A MMCA13EMMCA13E PB2RPB2RMMCA03EMMCA03E 18A18A 77 18A18A OB1PB4OB1PB4 SHAYSHAY GAPGAP 77 MMCA16EMMCA16E B' FIGURE 4.11 PandanusPandanus 11 Cross Section Location Plan

AUTHOR: KMH REPORT NO: 021 DRAWN: SHC REVISION: c DATE: 21 April 2009 SCALE: 1:1,000,000

E E E

E E E

E E E

E E E

E E E

E E E

m m m m m m JOB NO: 1033B PROJECTION: MGA94 m m m

m m m

m m m

m m m 0 0 0 Z50/51 Location: F:\Jobs\1033\MapInfo\021c_fig4.11.WOR

WEST CANNING BASIN MODEL DESIGN REPORT NUMERICAL MODEL

5 NUMERICAL MODEL

5.1 CODE SELECTION Modflow (McDonald and Harbaugh, 1998) is one of the i ndustry leading groundwater m odelling codes an d i s propos ed a s the comput ational/numerical code for si mulating the Wes t Ca nning Basin. The requi rement to devel op a Modfl ow model has al ready been agree d with DoW staff. Modflow i s well sui ted t o the nature of the aquifer uni ts of the West Ca nning area (gentl y sloping geometry and predominantly i sotropic aqui fer hydrauli c conducti vity) and we believe that a standard version of Modflow will be adequate to simulate the essential hydrogeological features of the system. A Modfl ow variant su ch as Modfl ow S urfact (Hydrogeol ogic, 1996 ), which a llows for a more rigorous treatment of the unsaturated zone hydrauli cs shoul d not be required for this work, nor for any model updates in the future. We understand that it is the preference of the DoW for the West Canning groundwater model to be delivered in the Vi sual Modflow Graphical User Interface ( GUI). Di scussions with DoW staf f have outlined the reasons for the preference. While Visual Modflow does have a range of useful and proven features, there is also some justification for the use of another well documented and supported GUI, Groundwater Vistas. A summary of the benefi ts and potential disadvantages of both of these GUIs is summarised in Table 5.1. Most of the benefits and disadvantages outlined are relevant to this project. T he only issues which are not relevant are related to limitations associated with Visual Modflow and the interface to Modflow Surfact. It is our intention to develop, calibrate, use the model for predictions and deliver it to the DoW in a si ngle GUI. We r ecommend th e use of Gr oundwater Vi stas for the range of features outlined abo ve. We do, however, understand th at the D oW have i n-house exp ertise and a preference in Visual Modflow and the model can be developed in this GUI, if required. While a number of i ssues are outl ined i n Tabl e 5. 1, the main i ssue that sug gests that Groundwater Vi stas woul d be the preferred GUI is the si mulation of evapotranspi ration. Groundwater Vistas allows evapotranspiration from any model layer (not jus t layer 1) an d also allows the evapotranspi ration surface to be s et at a ny elevation (Visual Modflow constrai ns this value t o g round s urface). T his issue is p articularly r elevant t o t he s imulation o f t he s prings, shallow water tables and constrained groundwater pumping using the ET pa ckage as outlined in Section 5.4.

5.2 MODEL SET UP The model will include features to simulate: ▼ Hydrogeological features of the aquifer system. ▼ Rainfall recharge to the aquifer. ▼ Groundwater inflow to and outflow from the modelled area. ▼ Groundwater pumping from the Broome Sandstone and Wallal Sandstone aquifer.

5.3 MODEL EXTENT, LAYERING AND GRID The model will be devel oped with five layers to i nclude two l ayers for the Wall al Sandstone (to enable a ssessment o f s ensitivity r elating t o t he Alexander F ormation), J arlemai Siltstone, Broome Sandstone and t he surficial sediments (Table 5.2). The model and all associated data will be pl otted usi ng the GD A94 Zone 51 coordinate system. Coordi nates of the pro posed rectangular model domain (four corne r points) are detailed in Table 5.3. E xtents of i ndividual aquifer units may be smaller than this maximum extent. A grid size of 500 metres is proposed for the majority of the model grid that is used to simulate the main land areas of th e aquifer units of interest. The off shore or ocean a rea (as outlined in Section 5.4 below) will include larger model cells, up to a maximum si ze of 1000 metres. Thi s results in a total of approxi mately 966,720 cells over the fi ve model layers. Recent experience indicates that model run times should not be problematic with this model dimensionality. There may be some scope to reduce the uniform grid size locally to 250 metres, if required.

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Table 5.1: Summary of Groundwater User Interface

GUI

Visual Benefits Well supported and Ease of use. In-house Excellent result Good interface Automatic stress Groundwater Modflow documented with ongoing expertise in DoW and output with GIS shape period setup pumping can be development viewing files created from time placed over capabilities series data, multiple layers however some based on screened caution is required intervals and a weighting equation. Time series pumping easily imported Disadvantages Evapotranspiration (ET) must Some limitations Cell re-wetting No matrix Water budgets not Limited capability be specified from the top grid associated with Modflow uses global arithmetic easily tabulated per in inputting layer and the ET surface Surfact models rather than capabilities stress period. Must Modflow input files must be equal to topography. spatially-varying look at time series (eg bas.dat, bcf.dat ET function cannot be used cell by cell differences to etc) to constrain pumping. Must parameters assess water use Modflow Surfact Fracture balance Well package to constrain components. pumping relative to a water level

Groundwater Benefits Well supported and Evapotranspiration (ET) Excellent result Supports most Groundwater Easy import and/or Vistas documented with ongoing can be specific from any and output GIS file types. pumping can be interpolation of development including layer and ET surface can viewing Basic matrix placed over data via text files personal service from be user specified. ET capabilities. Uses arithmetic multiple layers developers. Blog updated by function can then be only one file to capabilities based on screened developers used to assign store all model (useful for intervals and a (http://groundwater constrained groundwater related data. efficient data weighting equation models.blogspot.com/) pumping in standard Spatially-varying processing). Modflow cell re-wetting. Disadvantages Some specific skills required Some ambiguity in to use. Skills not currently hydrograph and mass available in-house at DoW balance views for large models

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Table 5.2: Layer Geometry

Layer Hydrogeological Unit Thickness 1 Surficial Sediments Top of layer to follow surface topography. Base of layer assigned consistent with GSWA data for base of alluvium. Thickness estimated to be between 2 and 10 metres 2 Broome Sandstone (Aquifer) Base of layer will be assigned consistent with GSWA and other data available for base of Broome Sandstone. Thickness estimated to be between 10 and 130 metres 3 Jarlemai Siltstone (Aquitard) Base of layer will be assigned consistent with GSWA data fro base of Jarlemai. Thickness varies between 10 and 120 metres. 4 and 5 Wallal Sandstone (Aquifer) Base of the Wallal will be assigned consistent with GSWA data for base of Wallal. Thickness layer of layer 4 (Alexander formation) will be set at approximately one- third the overall Wallal Sandstone thickness. Total thickness of Wallal (ie layers 4 and 5) varies between 20 and 370 metres.

Table 5.3: Model Domain

Grid Position Easting* Northing* North East 279000 7961470 North West 51000 7961470 South West 51000 7706210 South East 279000 7706210

* GDA94 Zone 51 (as project area crosses zones 50 and 51)

5.4 BOUNDARY CONDITIONS A groundwater i nflow boundary will be assi gned at the ups tream boundary of the Wal lal Sandstone aqui fer. The location of t he coastal or downstrea m outfl ow boundari es i s shown schematically in Figure 5.1 and 5.2. The northern boundary of the model will be set a di stance of approxi mately 9km from the co astline i n the west, to a pproximately 12 0km from th e coastline in the east of the Project area. Thi s approach wi ll a llow the coastal outflow, or downstream model boundary to be si mulated in such a way that the boun dary location will not overly constrain model results. For example, if a proposed borefield in the Wallal Sandstone is simulated close to the coast, the model boundary i s sufficiently far away that it will not result in under estimation of the impact of long term pumping. The p roposed s et up o f t he c oastal b oundary c ondition is s hown s chematically in s ection in Figure 5. 3. The ocean will be si mulated i n layer 1 usi ng the R iver Package in Modfl ow. The base of the “ri ver” cells will be set consi stent with available sea fl ow bathymetry data wi th the “head” in the river set consistent with mean sea level. The elevations of the ocean boundary (to be incorporated in the River package) will be set consistent with available monitoring data and consistent with information provided by Turner and Coates on how ocean boundaries should be specified (Turner et al , 1 996). The u nderlying layers wil l be assi gned a no fl ow condi tion a t their northern limit as it is assumed that all groundwater outflow will ultimately be to the ocean, driven by the di fference between the di scharging fresh water and the more sal ine sea water. This arrangement will not account for the density driven processes but will provide a suffici ent approximation t o t he in ferred g roundwater o utflow p rocess. I t w ill a lso a llow for an e arly assessment of the potential for saline intrusion via the reversal of flow directions at this model boundary. Rainfall recharge will be assigned consistent with analytical estimates to the saturated s urficial sediments and unconfined areas of the Broome and Wallal aquifers.

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Evapotranspiration from shallow water tabl es and/or spri ngs wi ll be simul ated using the Evapotranspiration (ET) package i n Modflow. The evaporative feature may need to be included in both layer 1 and/or layer 2, depending on the saturated thickness of the surficial sediments and t he Br oome Sa ndstone. I f Vis ual M odflow is u sed, it may b e difficult t o s imulate t his evaporative flux using the ET package and it may be necessary to use the drain package (DRN) in Modflow. Groundwater pumping will be si mulated by the pu mping wells (WEL package in Modflow) or if Groundwater Vi stas is adopted as t he GUI, vi a the ET pa ckage i n Modfl ow, wh ich allows minimum water levels or constrained pumping to be applied.

5.5 AQUIFER PARAMETERS Aquifer p arameter va lues wi ll b e r efined d uring model c alibration, h owever in itial e stimates based on available data are presented in Table 5.4

Table 5.4: Initial Aquifer Parameter Estimates

Aquifer/Aquitard Horizontal Vertical Hydraulic Confined Storage Specific Yield Unit Hydraulic Conductivity Coefficient Conductivity (m/d) (m/d) Surficial Sediments 1 0.1 NA 0.15 Broome Sandstone 7.5 0.75 5x10-4 0.15 Jarlemai Siltstone 0.001 0.0001 5x10-4 0.035 Alexander Formation 20 2 5x10-4 0.2 Wallal Sandstone 20 2 5x10-4 0.2

5.6 MODEL CALIBRATION The model will be calibrated in steady state (“long term average”) mode to measured (ass umed steady) water levels. Calibration will be assessed by quantifying the Scaled Root Mean Squared (SRMS) of measured ve rsus model led groundwat er l evels. In accordanc e wi th best practi ce modelling guidelines (MDBC, 2001), a S RMS value of less than 5% will be targete d, but model calibration p erformance may b e lim ited b y data availability. Pl ots of model led groundwater contours wi ll be presented overl aid wi th measured spo t hei ghts, al ong wi th scatter plots of measured and modelled hydraulic heads. The following data are available for transient model calibration: ▼ Data associated with the operation of the BHPBIO Shay Gap borefield. ▼ Groundwater level monitoring data at GSWA 20C.

This data does not show any si gnificant pi ezometric level changes over time. Therefore, the data can be used to provide a lower limit on aquifer storage values. The available C14 data will be used to test if the model, prior to the inclusion of any additional borefield pumping (other than Shay Gap), is able to replicate groundwater travel times inferred from the data. It is assumed that the data currently available will be incorporated and that any data that becomes available in the future wi ll be used as part of further model calibration and development under an extended work programme. As requi red, all other model ling activi ties wi ll be compl eted i n accordanc e wi th best practi ce modelling guidelines (MDBC). I f this is not achievable, the implications will be discussed with DoW staff as soon as possible to identify impacts on the project and an implementable solution.

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LOCATION MAP

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77775500000000°°°NN FIGURE 5.1 Model Extent and Boundary Conditions (Broome Aquifer)

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FIGURE 5.2 77775500000000°°°NN Inflow Boundary Model Extent and Boundary Conditions (Wallal Aquifer)

77772255000000°°°NN AUTHOR: AP REPORT NO: 021 DRAWN: AN REVISION: ... DATE: 05/03/09 SCALE: 1:1,500,000 77770000000000°°°NN 77770000000000°°°NN JOB NO: 1033B PROJECTION: MGA94 F:\Jobs\1033B\MapInfo\021b_Fig5.2.WOR Z51

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SCHEMATIC BOUNDARY CONDITIONS SET-UP FIGURE 5.3

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WEST CANNING BASIN MODEL DESIGN REPORT REFERENCE LIST

6 REFERENCE LIST

Apak, S. N and Carl sen, G. M. 1997 . A Compilation and Review of Data Pertaining to the Hydrocarbon Prospectivity of the Canning Basin. Geological Survey of Western Australia. Record 1996/10. Perth, Western Australia. Aquaterra. 2007. Canning Basin Groundwater Supply – Spinifex Ridge Project. Report pre pared for Moly Mines Pty Ltd. Reference no. 689/C5/328b. Perth, Western Australia, September 2007. Aquaterra. 2008. BHP Billiton Iron Ore Pty Ltd, Annual Aquifer Reviews, July 2007 to June 2008 (Shay Gap), Prepared for BHPBIO, Perth, Western Australia, 2008. Aquaterra. 2009. Ridley Magnetite Project Water Supply Hydrogeology Report. Prepar ed fo r Engenium / Atlas Iron Pty Ltd. Reference no. 783C\069b. Perth, Western Australia, March 2009. Hydrogeologic Inc. 1996. Modflow Surfact. Leech, R. E. J. 1979. Geology and Groundwater Resources of the Southwestern Canning Basin Western Australia. Geological Survey of Western Australia. Record 1979/9. Perth, Australia. McDonald, MG and Ha rbaugh, A .W. 1988. A modular three-dimensional finite-difference groundwater flow model: US Geological Survey Techniques of Water Resource Investigation, book 6, chap. A1 586p Murray-Darling Basi n Commi ssion. 2001. Groundwater Flow Modelling Guideline. P repared for the Murray Darling Basin Commi ssion by Aqua terra Consul ting Pty Lt d. Adel aide, South Australia, 16 January 2001. Rowston, D . L. 1976. West Canning Basin Groundwater Geophysical Final Report. Ge ological Survey of Western Australia, Record 1976/9. Perth, Western Australia. Rumbaugh, J and Rumbaugh. 1995-2005. Groundwater Vistas. Turner, I.L., Coates, B.P., and Acworth R.I. 1996. The effects of tides and waves on water table elevations in coastal zones. Hydrogeology Journal. Vol 4, no.2, 1996. pp51-69 Waterloo Hydrogeologic Inc (a division of Schlumberger). 1994 to present. Visual Modflow.

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