Report on Kemmis II Pit Groundwater Impact Assessment ... · Originally opened on a trial basis, ... existing Kemmis Pit that is located to the southeast and thought to be in the

Report on

Kemmis II Pit Groundwater Impact Assessment South Walker Creek Coal Mine

via Nebo, Northern Bowen Basin Central Queensland

Prepared for BHP Mitsui Coal

Project 80275.00 December 2013

Document History

Document details Project No. 80275.00 Document No. 0 Document title Kemmis II Pit Groundwater Impact Assessment

Site address South Walker Creek Coal Mine via Nebo, Northern Bowen Basin, Central Queensland

Report prepared for BHP Mitsui Coal

File name P:\Brisbane 2013\80275.00 - South Walker Creek Groundwater Impact\Report\80275 Kemmis II Groundwater Impact Assessment

Document status and review Revision Prepared by Reviewed by Date issued

1 Mick Stadter Carl Deegan 10 September 2013 2 Mick Stadter Carl Deegan 19 December 2013

Distribution of copies Revision Electronic Paper Issued to

1 1 Tyson Smalley – BMC Metallurgical Coal

The undersigned, on behalf of Douglas Partners Pty Ltd, confirm that this document and all attached drawings, logs and test results have been checked and reviewed for errors, omissions and inaccuracies.

Signature Date

Author

18 December 2013

Reviewer

18 December 2013

Reviewer

18 December 2013

Douglas Partners Pty Ltd

ABN 75 053 980 117 www.douglaspartners.com.au

439 Montague Road West End QLD 4101

Phone (07) 3237 8900 Fax (07) 3237 8999

Kemmis II Groundwater Impact Assessment Project 80275.00 South Walker Creek Coal Mine, via Nebo, Central Queensland December 2013

Executive Summary

South Walker Creek Coal Mine (SWC) is located 40 km west of Nebo in Central Queensland and has been in operation since 1996. SWC is an open cut mine currently producing 6.2 million tonnes of coal per annum. The mine is presently being managed by BHP Mitsui Coal (BMC). BMC is seeking to progress operations at SWC via the proposed development of the Kemmis II Pit, which is essentially an extension of the existing Kemmis Pit. In order to secure surface rights for the proposed Kemmis II Pit, BMC is required to complete a number of legislative approval processes, including an EA amendment and possible authority under the Water Act. Douglas Partners Pty Ltd (DP) was engaged by BMC in July 2013 to undertake a Groundwater Impact Assessment for the Kemmis II Pit, in order to fulfil legislative approval requirements relating to groundwater, and to secure surface rights in relation to the development of the proposed pit. This report covers a desktop study which addresses the impacts of the Kemmis II Pit development on groundwater levels, groundwater quality, and any associated impact to groundwater dependent ecosystems. Through evaluating these impacts, DP has also been able to assess and provide advice regarding potential impacts on existing users of the groundwater system. The following components were completed as part of the agreed scope of work:

Description of the spatial extent and properties of aquifers and aquitards;

Reporting of groundwater levels and assessment of groundwater gradients and flow directions;

Characterisation of groundwater quality;

Quantification of aquifer recharge;

Identification of potential groundwater discharge zones; and

Development of a Conceptual Hydrogeological Model (CHM). The CHM is a description of the groundwater system and the major processes occurring within it.

The CHM recognises two groundwater systems at the South Walker Creek operations, viz:

A shallow aquifer within the Tertiary to Quaternary sediments; and

A deeper aquifer within the Permian Rangal Coal Measures and Triassic fractured Rewan Formation Units.

Strata of the deeper Permian and Triassic strata host groundwater resources, primarily within coal seams of the Rangal Coal Measures. The Permian groundwaters:

Are characterised by low permeability and storage where water is predominantly stored and transmitted by secondary porosity features such as fractures, faults, discontinuities of the rock mass, and though coal seam cleats;

Are confined by the lower permeability host rock matrix;

Contain poor quality (moderately saline) groundwater;


Are poorly recharged due to low permeability confining strata;

Are not widely utilised due to quality and yield constraints;

Have been classified historically as a discontinuous and low value resource in the vicinity of a high impact activity, and;

Are not at high risk of contamination from mining and mining related activities. The other potential source of groundwater can be found within the Tertiary to Quaternary sediments, which are generally quite thin and poorly developed. Information concerning groundwater hosted within this sequence is limited due to the fact that the unit is not spatially continuous. An examination of some 3,390 exploration holes from site shows that of all holes drilled, nearly 30% have been flagged as being dry, and a further 13% have been flagged as being damp only. This indicates that the younger sequence is very poorly developed, and as the CHM shows, the potentiometric surface closer to site occurs within the older Permian formations. Observations and data obtained from the existing operations at SWC have enabled DP to construct an analytical model which predicts likely groundwater inflows to the Kemmis II Pit, and the radius of influence that the pit will have on the local groundwater system. A second analytical model was developed to estimate both the amount of recharge occurring near the existing mine operations, and to estimate aquifer storage which was then used to assess the parameters adopted in the mine inflow analytical model. Results show that dewatering for the Kemmis II Pit will be dominated by surface water (from incident rainfall and runoff) rather than groundwater inflows through the low permeability rockmass. Analytical modelling suggests that the range of likely groundwater inflow to the Kemmis II Pit will be between 2 L/s and 6 L/s, while the radius of influence of the mine on the local groundwater system will likely be between 1.5 km and 2.4 km. Due to the low rates of groundwater inflow to the proposed Kemmis II Pit, the impact to the regional groundwater system is assessed to be low, resulting in minimal drawdown within the Permian aquifer locally. Reduced groundwater pressures will be concentrated in close proximity to the pit due to the limited propagation of the cone of depression or drawdown within the low permeability rockmass. The drawdown will not significantly impact on any existing groundwater users. Groundwater quality is unlikely to change significantly due to the low volumes of discharge, and subsequently any groundwater dependent ecosystems which have not previously been mapped, are unlikely to be affected, including the nearby QR Farm Dam. Should the Kemmis II Pit be approved, an appropriate EA amendment should include an expanded groundwater monitoring network. Recommendations for additional monitoring of the groundwater system are included in this report.


Table of Contents

Page

1. Introduction ...................................................................................................................... 1

2. Project Objectives & Scope of Work ............................................................................... 2

3. Data Sources ................................................................................................................... 2

4. South Walker Creek – Site Specifics ............................................................................... 3

5. Physiography & Climate .................................................................................................. 4

5.1 Topography & Drainage ........................................................................................ 4

5.2 Climate .................................................................................................................. 4

6. Regional Geology ............................................................................................................ 5

7. Conceptual Hydrogeological Model ................................................................................. 6

7.1 Aquifers & Hydraulic Properties ............................................................................ 6

7.1.1 Tertiary / Quaternary Alluvial Aquifer ......................................................... 6

7.1.2 Permian Fractured Rock Aquifer ............................................................... 7

7.2 Groundwater Levels & Flow Directions ................................................................. 8

7.2.1 Tertiary / Quaternary Alluvial Aquifer ......................................................... 8

7.2.2 Permian Fractured Rock Aquifer ............................................................... 8

7.3 Recharge ............................................................................................................. 10

7.4 Groundwater Quality ........................................................................................... 12

7.5 Groundwater Utilisation ....................................................................................... 13

7.6 Conceptual Hydrogeological Model Cross Section ............................................. 20

8. Mine Impact Assessment .............................................................................................. 21

8.1 Estimates of Mine Inflows ................................................................................... 21

8.2 Impacts to Groundwater Levels and Quality ....................................................... 22

8.3 Groundwater Dependent Ecosystems (GDE’s) ................................................... 24

8.4 Recommendations .............................................................................................. 25

9. Summary ....................................................................................................................... 26

10. Limitations ..................................................................................................................... 28

11. References .................................................................................................................... 29


Drawings

Drawing 1: Location of Kemmis II Pit Drawing 2: Site Layout - South Walker Creek Mine Drawing 3: Regional Topography & Surface Drainage Drawing 4: Long Term Annual Rainfall Trends Drawing 5: Long Term Monthly Rainfall and Evaporation Drawing 6: Regional Geology Drawing 7: Water Encountered in Coal Exploration Bores Drawing 8: DNRM Database – Regional Bores Drawing 9: DNRM Database – Bore Yields Drawing 10: Composite Piezometric Contours Drawing 11: Depth to Piezometric Surface Drawing 12: Combined Long Term Hydrograph Drawing 13: Recharge Estimate (CRD Method) Drawing 14: Regional Bore Salinity Drawing 15: MT1 Coal Seam Isopach Drawing 16: MT2 Coal Seam Isopach Drawing 17: MB2 Coal Seam Isopach Drawing 18: Hydrogeological Cross Section Drawing 19: Analytical Prediction of Mine Inflows Drawing 20: Kemmis Pit Mine Pumping Against Rainfall Drawing 21: Sub Surface Reliant Groundwater Dependent Ecosystem Drawing 22: Proposed Monitoring Sites Appendices

Appendix A: Hydrograph plots Appendix B: Geochemistry plots Appendix C: Annual Monitoring Reviews

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Kemmis II Groundwater Impact Report

South Walker Creek Coal Mine

via Nebo, Central Queensland

1. Introduction

South Walker Creek Coal Mine (SWC) is located 40 km west of Nebo in Central Queensland and has been in operation since 1996. The mine currently produces 6.2 million tonnes of coal per annum, which is supplied to steel manufacturers as pulverised coal that supplements more expensive coking coal during the production process. Originally opened on a trial basis, SWC is an open cut mine which operates on a 16 km long strike that was initially found to be 11 to 12 m thick, and dipping west at eight degrees. SWC is estimated to have reserves in the order of 80 million tonnes of coal and is presently being managed by BHP Mitsui Coal (BMC). BHP Mitsui Coal is seeking to progress mining activity on the existing Mining Lease (ML4750) via the proposed development of the Kemmis II Pit. The proposed pit is essentially an extension of the existing Kemmis Pit that is located to the southeast and thought to be in the direction of associated groundwater flow. To secure the surface rights for the proposed Kemmis II Pit area, BMC is required to complete a number of legislative approval processes, including an EA amendment and possible authority under the Water Act. BHP Mitsui Coal currently operates the SWC open cut coal mine near Tootoolah Homestead, off the Peak Downs Highway in Central Queensland. The SWC Mine consists of the Toolah, Walker, Carborough, Mulgrave and Kemmis open cut pits and operates all pits under Environmental Authority MIN100552107 administered by the Queensland Department and Resource Management (DERM). A key component of environmental management at the SWC Mine is the quantification of groundwater resources and the assessment of mining impact on these resources. This is currently facilitated by a groundwater monitoring network, groundwater monitoring program, and annual reviews of the groundwater data collected and assessed against defined trigger values. Currently, there is limited information available regarding the groundwater resources and potential impacts upon the resource to the northwest at the proposed Kemmis II Pit. BHP Mitsui Coal commissioned Douglas Partners Pty Ltd (DP) to develop a Conceptual Hydrogeological Model (CHM) for the proposed Kemmis II Pit, to characterise the groundwater system at the site and assess any potential impacts on groundwater resources, in regard to both groundwater levels and groundwater quality, and whether these impacts are likely to affect existing groundwater users or the environment, noteably groundwater dependent ecosystems. This report provides a description of the CHM based on the desktop review of the relevant groundwater information and data for SWC Mine, identifies potential contaminant sources at the mine site, and provides an assessment of the likely impacts which may result from the development of the Kemmis II Pit. The co-ordinate base for this project is the Australian Geodetic Datum 1984 (AGD84) and the elevation datum is the Australian Height Datum (mAHD). Drawing 1 shows the location of the proposed Kemmis II Pit.

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2. Project Objectives & Scope of Work

DP was engaged by BMC in July 2013 to produce a Kemmis II Groundwater Impact Report to fulfil the legislative approval requirements relating to groundwater, and to secure surface rights in relation to the development of the proposed pit. The primary objective of this investigation was the development of a Conceptual Hydrogeological Model (CHM). A CHM is a description of a groundwater system, including:

Description of the spatial extent and properties of aquifers and aquitards;

Reporting of groundwater levels and assessment of groundwater gradients and flow directions;

Characterisation of groundwater quality;

Quantification of aquifer recharge; and

Identification of potential groundwater discharge zones. The CHM defines the limit of knowledge of the groundwater system for the project and surrounding areas and forms the base of any later analytical or numerical groundwater flow modelling which may be required. Subsequent to the completion of the CHM, the scope of work included:

Preparation of analytical estimates of groundwater inflows to the proposed Kemmis II Pit, and;

Assessment of the likely impacts caused to the local groundwater system, other groundwater users and the environment in response to the development of the Kemmis II Pit.

This report outlines a desktop study which addresses the impacts of the Kemmis II Pit development on groundwater levels, groundwater quality, and any associated impact to groundwater dependent ecosystems. Through evaluating these impacts, DP has also been able to assess and provide advice regarding potential impacts to existing users of the groundwater system. 3. Data Sources

A number of study reports and available datasets were reviewed in order to synthesise data to contribute to the compilation of the CHM. These included:

Groundwater level and quality data from 5 monitoring bores (2 of which have only 6 months of data);

Geology and groundwater level information from 3,390 resource exploration drill logs;

Geological surface datasets (as .xyz files) of major lithological boundaries from the clients geological database;

Mine plan data and historical mine elevation plans (5 temporal slices);

Multiple surface topography survey datasets;

Dewatering volumes recorded from site;

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High resolution aerial imagery raster;

Permeability data derived from injection tests within coal seams at SWC;

General notes regarding site stratigraphy;

BHP Mitsubishi Alliance (BMA) South Walker Creek Annual Mine Review 2009; and

Historical annual groundwater data reviews (AGE, 2010 and GHD, 2012). Other data sources used to develop the CHM include:

Groundwater information from the Department of Natural Resources & Mines (DNRM) Groundwater database;

Climatic data from the Department of Science, Information Technology, Innovation and the Arts (SITIA) SILO Database;

Information downloaded from the Bureau of Meteorology’s Atlas of Groundwater Dependent Ecosystems;

Regional Shuttle Radar Topography Mission (SRTM) elevation data downloaded from the United States Geological Survey (USGS); and

Landsat Imagery downloaded from the USGS. 4. South Walker Creek – Site Specifics

South Walker Creek Coal Mine (SWC) is approximately 20 km northwest of Tootoolah Homestead, adjacent to the Peak Downs Highway in Central Queensland (Drawing 1). The SWC Mine consists of the Toolah, Walker, Carborough, Mulgrave and Kemmis open cut pits and operates all pits under Environmental Authority MIN100552107. Open cut mining operations are undertaken under the main mining lease, which is ML4750. Locally, the principal economic seam is the Main Seam that splits to the north and south and is known as Main Tops and Main Bottoms. The Main Seam is believed to be equivalent with the combined Elphinstone Seam and upper part of the Hynds Seam at nearby Hail Creek Coal Mine. The Main Seam extends over two kilometres in strike length in the southern part of the deposit and comprises 10.5 to 14 m of mainly dull to dull banded coal with minor mudstone partings. At the location of the proposed Kemmis II Pit, the Main Seam splits, and with depth can be intersected as MT1, MT2, or MB2. The latter of these 3 units is the thickest coal seam, generally averaging around 7 m. To the northwest, the principal seam to be mined is MT2 and this layer pinches out to the northeast of the proposed 10 year Kemmis II mine plan footprint. The coal seams in Kemmis II Pit will likely be accessed by low wall ramps where excavators/front end loaders are used to mine and load the coal. Drawing 2 shows the location of the proposed Kemmis II Pit at South Walker Creek Coal Mine.

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5. Physiography & Climate

5.1 Topography & Drainage

Drawing 3 shows the surface topography and drainage near the mine site, which is characterised by the high elevations of the north-northwest to south-southeast trending Carborough Range, to the west of the present mine site. Elevations along the range typically vary between 300 mAHD and 700 mAHD, while the flatter, lower relief lands typically only vary between 150 mAHD and 300 mAHD. The elevation of the undisturbed mine site is generally between 220 mAHD and 250 mAHD. The two most significant water courses near the mine site are the Walker Creek and Carborough Creek. Walker Creek runs roughly northwest to southeast through the South Walker Creek Mine lease. Carborough Creek joins Walker Creek near Mulgrave Pit within the north-western portion of current mine operations (Drawing 2). Walker Creek also joins Bee Creek, which runs in a southerly direction adjacent to the south-eastern lease boundary. The site contains a number of water storages and settlement ponds (GHD, 2012). Both creeks originate from the higher elevations associated with the Carborough Range, and eventually drain to the east and southeast towards lower topography. 5.2 Climate

South Walker Creek Mine is located at an approximate latitude of 21.75°S, some 150 km inland from the Queensland coast. Several weather stations are located nearby, with the closest at Oxford Downs and Nebo approximately 25 km east-southeast and east-northeast of the site respectively. Climate data for the site were collated from the Queensland Department of Science, Information Technology, Innovation and the Arts (SITIA), Silo database, which interpolates data from point observations to generate a representative dataset for a given location. Data obtained from the Silo database covers the period from 1900 to 2013 and indicates a long-term annual average rainfall of approximately 600 mm for the site (Drawing 4). Average monthly data indicate a seasonal climate, with the Wet Season summer months of December to March accounting for ~60% of annual total rainfall (Drawing 5). In contrast, only ~14% of annual rainfall occurs during the Dry Season months of June to September. Average evaporation for the year is in excess of 2,000 mm, approximately 3.5 times the average total rainfall, which also peaks in the summer months. The ratio of evaporation to rainfall is lowest during January and February, suggesting that high rainfalls during these months may provide the bulk of recharge to the groundwater system over the long term. Average daily maximum temperatures range from 33oC for the month of December down to 23oC for June and July. Average daily minimum temperatures are 12oC to 14oC lower than average daily maxima (Drawing 5).

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Table 1 summarises the monthly average climate statistics for the South Walker Creek Mine region, which are shown graphically on Drawing 5. Table 1: Long-Term Average Monthly Climate Statistics

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

Rainfall (mm) 110 104 78 34 27 31 21 18 15 28 54 88 607

Evaporation (mm) 220 180 187 149 117 97 105 132 172 214 224 233 2,029

Max. Daily Temp (oC) 32 32 31 29 26 23 23 25 28 30 32 33 29

Min. Daily Temp (oC) 22 21 20 17 13 10 9 10 13 17 19 21 16

6. Regional Geology

The regional geology surrounding South Walker Creek Mine generally comprises Triassic and Permian sedimentary units overlain by surficial deposits of Tertiary and Quaternary age. The surface geology of the region is shown on Drawing 6. The geology in the vicinity of South Walker Creek Mine is characterised by the following stratigraphic units (from youngest to oldest):

Unconsolidated alluvium and colluvium (Quaternary and Tertiary);

Rewan Group (Triassic);

Rangal Coal Measures (Permian); and

Fort Cooper Coal Measures (Permian).

Drilling records suggest that the Quaternary and Tertiary alluvium sediments (where present), are generally <20 m thick and comprise of clays, sandy clays and sands. Information concerning this unit is limited, however it is apparent that the unit attains a maximum thickness in proximity to present and past palaeochannels associated with Walker and Carborough Creeks. The southern end of the proposed Kemmis II Pit is the closest point to the alluvial sediments (approximately 200 m), while the northern end of the proposed pit is some 1.1 km from the boundary of the alluvium, as shown on the 1:100K geological map (Map Sheet 8554). The Triassic Rewan Group consists of thinly interbedded green to reddish brown mudstone, siltstone and fine lithic sandstone. The Rewan Group generally conformably overlies the Rangal Coal Measures. The transition between the Rewan Group and the Rangal Coal Measures is sometimes difficult to define and is often based on a change in colour.

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The Rangal Coal Measures are of Late Permian age and part of the Blackwater Group. The Rangal Coal Measures are comprised of grey mudstone and siltstone, fine-grained lithic sandstone, tuff, carbonaceous shale and coal seams. The Rangal Coal Measures and equivalents represent the final phase of development of coal forming conditions in the Bowen Basin. The unit conformably overlies the Fort Cooper Coal Measures. The underlying Late Permian Fort Cooper Coal Measures is also part of the Blackwater Group. The rocks are described as green and grey mudstone, siltstone, subordinate fine sandstone and minor seams of coal and carbonaceous mudstone. Coal seams of the Fort Cooper Coal Measures are intensively banded with tuffaceous claystones, and are of marginal or no economic value. The upper boundary of the Fort Cooper Coal Measures is characterised by the Yarrabee Tuff, a distinctive marker bed found across the Bowen Basin. The Yarrabee Tuff, and its characteristic high gamma response in downhole geophysical logs, marks the transition between the Rangal Coal Measures and the Fort Cooper Coal Measures at South Walker Creek. The proposed Kemmis II Pit is located on the boundary of the Rewan Formation (Rr) and the Rangal Coal Measures (Pwj). Coal seams of the Rangal Coal Measures form the economic basis for the Kemmis II Pit. 7. Conceptual Hydrogeological Model

7.1 Aquifers & Hydraulic Properties

A review of hydrogeological data and previous groundwater investigations has shown that the hydrogeology of South Walker Creek and adjacent areas is characterised by two distinctly different groundwater systems; viz:

1. Shallow aquifer within the Tertiary to Quaternary sediments; and 2. Deeper aquifer within the underlying Permian to Triassic Strata.

7.1.1 Tertiary / Quaternary Alluvial Aquifer

IESA (2003) provides results for two monitoring bores, Hut Bore and Kiss’ Bore, which were reported to be stock watering bores located in close proximity to Walker Creek and close to the northern boundary of mine operations at that time (north of Mulgrave Pit). Kiss’ Bore has been monitored for water quality during the period October 2000 to May 2013, but does not have records of water level information. Similarly, Hut Bore has not been monitored for water level, but does have some historic water quality readings during the period October 2000 to January 2003. Hut Bore is believed to have been decommissioned. Kiss’ Bore is believed to abstract groundwater from the Tertiary sediments and this resource is of suitable quality for stock watering purposes. Unfortunately, no yield information or other hydraulic data are available for either bore, so it is difficult to determine hydraulic properties for this aquifer.

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Drawing 7 shows the location of coal exploration bores drilled by SWC which have some form of water data recorded against the hole id. A statistical analysis shows that of the 3,390 holes, approximately 30% have been flagged as being ‘dry’, while a further 13% have been classified as ‘damp’. It is observed that of all the holes drilled adjacent to the proposed Kemmis II Pit, very few made significant amounts of water during the drilling process. Further to the south where a greater thickness of alluvium might be expected, the ratio of ‘wet’ holes increases significantly, which does support the anecdotal evidence that the Tertiary aquifer is very limited in its lateral continuity. It should be noted that exploration holes which had no indication of dryness, yet had a post drilling water level taken, were considered to be ‘wet’ holes. This makes this simple analysis somewhat conservative. Douglas Partners undertook a search of the Department of Natural Resources and Mines (DNRM) Groundwater Database to identify registered bores within a 30 km radius of the mine site (Drawing 8). Drawing 9 shows the recorded yield values for all bores in the region, and highlights the data gap for alluvial bores near the proposed Kemmis II Pit. As previously mentioned, geological mapping (Drawing 6) shows the approximate extent of alluvial deposits associated with Walker and Carborough Creeks. In these areas it may be expected that the alluvium provides a greater range of hydraulic parameters, depending on the lithology and thickness of the aquifer. A typical range may be of the order of 0.2 to 20 m/day. No values of storage appear to have been documented for this unit locally. It is understood that the alluvial aquifer is unconfined. DP suggests (based on experience with similar groundwater systems) that the unconfined storativity of the alluvial aquifer would be of the order of 10% to 20%. 7.1.2 Permian Fractured Rock Aquifer

Based on review of available material, it is evident that flow through the Permian aquifer is likely to be dominated through secondary porosity features such as fractures, faults, discontinuities of the rock mass, and though the coal seams and cleats. The aquifer is characterised by the following:

Confinement by the lower permeability host rock matrix;

Of sub-regional extent with beds locally dipping towards the west in a larger syncline system;

Unconformably overlain by a thin capping of Tertiary sediments; and

Containing coal seams with hydraulic parameters which are 1-2 orders of magnitude higher than the bulk rock parameters.

Groundwater associated with coal seams has been recognised from increased “water-make” during coal exploration drilling programs, when coal seams are intersected. The Geological Survey of Queensland, in partnership with the CSIRO, undertook a series of investigations in the early 1980s to better understand the hydrogeology of the Rangal Coal Measures near Curragh (Muller & Hair, 1980; Muller, et. al., 1983; and Hair, 1987). These investigations focussed on the Aries, Castor and Pollux Seams, and found that coal seams were the primary aquifers of the Rangal Coal Measures sequence. From a program of hydraulic testing including test pumping and field permeability testing, the hydraulic conductivity (K) of coal seams was found to be ~1.2 x 10-1 m/day. Interseam sediments (siltstones and sandstones) were

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found to be 1 to 2 orders of magnitude less permeable than the coal seams (average K: ~9.7 x 10-3 m/day). Results of the analysis of test pumping data show that Transmissivity (T) of coal seam aquifers is of the order of 3.8 x 10-1 m2/day, and that storativity (S) values average 1.7 x 10-4. Hair (1987) found that the coal seam aquifers were significantly anisotropic, with a principal direction of enhanced Transmissivity and hydraulic conductivity aligned (approximately) with regional structure. This desktop assessment has not been able to locate any documented hydraulic parameters for the interburden (bulk rock mass of the Permian aquifer) locally, however some hydraulic parameters for the coal seams at SWC have been made available (K&A, 2013). The MB2 seam has been tested in 4 holes through Injection Falloff Tests (IFT’s) and reported permeability values in millidarcy (mD). From this report DP can deduce the following parameters for the coal seams at SWC:

Permeability range of 7.09 to 47.64 mD with a geometric mean of 23 mD which equates roughly to a mean hydraulic conductivity of 0.015 m/d

7.2 Groundwater Levels & Flow Directions

7.2.1 Tertiary / Quaternary Alluvial Aquifer

Very little information is available in regard to groundwater levels in the Tertiary / Quaternary alluvial sequence associated with Walker and Carborough Creeks. Due to the limited spatial nature of the alluvial aquifer, only two local bores believed to be completed in this unit near the mine site (Kiss’ and Hut Bore) have been identified in this study, unfortunately neither bore has recorded water levels. Douglas Partners undertook a search of the Department of Natural Resources and Mines (DNRM) groundwater database to identify registered bores within a 30 km radius of the mine site. These bores are discussed in further detail below, but due to the paucity of data and limited continuity of this aquifer, it is not presently possible to construct a groundwater contour plan for the Tertiary aquifer. Drawing 8 shows the closest bore completed within this unit is RN 85403, however this bore has no groundwater level information. RN 85403 occurs approximately 10.5 km from the proposed pit and had a yield upon completion of 0.5 L/s. It is likely that if this aquifer was broader in extent, thicker, more transmissive and could supply reasonable quality groundwater, then data paucity would not be an issue. Based on the regional topography, natural surface water drainage features and geological mapping, it is most likely that where the Tertiary aquifer is sufficiently developed near SWC, the groundwater flow direction will generally be towards the south to south east, but may change locally near adjacent surface water features, especially during times of high river level. 7.2.2 Permian Fractured Rock Aquifer

Drawing 2 shows the locations of existing monitoring bores P10672 and P10680 which both target groundwater within the Permian sediments (in the overburden above the coal deposits) and have screen depths of 26 m to 30 m and 21 m to 29 mbGL respectively. Inflow rates of 0.02 L/s and 0.1 L/s

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were reported for monitoring bores P10680 and P10672 respectively (IESA 2003) indicating a relatively low yield for the Permian aquifer at these locations. A third monitoring bore P9456, located in the southern exploration blocks and south of the Walker / Toolah Pit is believed to have targeted groundwater within the “Mains Bottom Seam”. The water level in monitoring bore P9456 was reported to drop from 21 mbGL to 38 mbGL from 2000 to 2002 indicating that mining of the seam had resulted in seam dewatering. Water level monitoring of this bore ceased in 2002 when the pumping equipment became permanently lodged, and sampling ceased when the pumping equipment broke down in 2003 (GHD, 2012). The occurrence of groundwater within the Permian sediments was reported by IESA (2003) to be sporadic and localised. For instance, the IESA report states that no groundwater was encountered in test drill hole P10681 (to a depth of 48 mbGL) located within 5 m of monitoring bore P10680. This was attributed to the fractured nature of the Permian aquifer. Moreover, it was reported that no groundwater within the Tertiary or Permian sediments was encountered in drill hole P10679 (to a depth of 73 mbGL) located adjacent to the northern boundary of the Mulgrave Pit indicating limited occurrence of groundwater in the northern lease area (GHD, 2012). DP notes that, even while drilling may not intersect significant quantities of groundwater sufficient to develop for supply purposes, that even ‘dusters’ will slowly recover and provide a water level which is then able to be used to construct a piezometric surface. It is for this reason that a composite groundwater contour plan of piezometric head was developed to map the groundwater flow net in the region. GHD (2012) questions the validity of such a model, however while most of the flow may occur through the joints and voids in fractured rock, it is still the piezometric level within the bulk rock mass that drives these processes. Drawing 10 shows a composite groundwater contour plan which was generated from:

Five bores which had water levels at SWC;

3,390 exploration holes which had recovered water levels post drilling;

An additional set of exploration data from Kemmis Pit; and

Bores within the groundwater database which were deemed as being completed in the deeper aquifer.

Where possible, the latest groundwater data were used for contouring, but in most instances, temporal data were not available. Contours were generated by hand using all available data including topography where required to check the validity of sub surface contours. It should also be noted that while the exploration holes were used as a guide, they were not used for detailed resolution at the pit scale. Due to the low permeability of the bulk aquifer matrix, local drawdown could be seen from the exploration holes adjacent to the existing pit, and if warranted in the future, this local scale drawdown could be superpositioned onto the regional contour set. The composite piezometric contours show that:

Groundwater flows from the higher elevations associated with the Carborough Range, to the east, south and southeast towards the lower topographic area; and

At the proposed Kemmis II Pit, the direction of groundwater flow is to the southeast, and the hydraulic gradient is 20 m over 8,700 m, or 1 in 435.

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Drawings 9 & 10 can be used to guide the assessment of likely impacts to groundwater resources due to the proposed pit. Based on the extent of alluvium shown, it is probable that the closest Tertiary aquifer of any significant thickness may exist to the south to south west of the proposed pit. It is likely that in this region, if the Tertiary sediments do host significant quantities of groundwater (there are no registered bores in proximity to the pit), that the general groundwater flow direction will be towards the south to southeast, away from the pit.

The piezometric contour plan was subtracted from a composite topographic layer (created from regional SRTM data and local mine site survey data) to present a depth to top of piezometric surface plan. This should not be taken as a depth to water plan, because in reality it is only a potential depth to water plan. Drawing 11 shows the areas where groundwater may exist at shallow depths, for subsequent analysis. It can be interpreted from the depth to piezometric surface plan that:

The most shallow groundwater areas coincide with topographically low terrain with present surface water features; and

At the proposed Kemmis II Pit, the potential depth to piezometric surface is of the order of 20 to 30 m.

While DP has been unable to find sufficient water level data from bores completed within the Tertiary / Quaternary aquifer, where this aquifer does exists, the vertical hydraulic gradient between the alluvium aquifer and the Permian aquifer is likely to be vertically downwards. This is because the hydraulic head in the Permian unit is largely contained within the Permian sediments. Further information from bores completed within the alluvium would need to substantiate this, ideally with nested sites completed in both units. DP was only able to find two hydrographs for bores completed in the Permian aquifer which had a sufficient temporal record for further analysis. Those bores are monitoring bores P10672 and P10680 which form part of the groundwater monitoring requirement under the EA. The hydrographs for these bores are discussed in further detail in the Section 7.3 of this report. A combined hydrograph for 5 of the regional Permian bores is presented in Appendix A. 7.3 Recharge

SILO climate data have been used to prepare a Rainfall Residual Mass Balance for investigating the correlation between groundwater level response and above or below average rainfall. Drawing 12 presents hydrographs for monitoring bores P10672 and P10680, and the residual mass balance. The comparison of hydrographs with the residual mass balance shows that:

Monitoring bore P10680 (located ~3.4 to 3.5 km from the Toolah Pit) exhibits a similar response to rainfall through the bulk of the monitoring record, with relatively static water levels through 2006/7, rising head in response to above average conditions in late 2007, and with a later time rise in late 2010. Within the last couple of years this hydrograph has continued to rise in tandem

11 of 30


with slightly above average rainfall (analysed over the shorter period 2005 – 2013), while the longer term hydrograph shows above average rainfall since 2008; and

Monitoring bore P10672 (located ~800 m from the Toolah Pit) shows a poorer correlation through the analysed period with the main point of difference being late time data where the hydrograph continues to fall during periods of above average rainfall (ie late 2010 and into 2011). While over the whole period P10680 has risen some 2.2 m, P10672 has fallen 0.83 m. This could indicate that the effects of mining are being observed closer to the pit while at distances greater than 3 km, no effect from mining is measurable.

DP has utilised the Cumulative Rainfall Departure (CRD) method for estimating the amount of recharge which the groundwater system receives through rainfall. The CRD method is based on the relationship between rainfall and observed groundwater levels and can be used for calculating estimates of recharge rates and storativity / specific yields. The general equation relating CRD to groundwater level fluctuations (Wenzel, 1936) takes the form: Where;

hi = h(i-1) + F(Pi – C)/S + (Ii – Oi)/SA – Qi/SA

hi = Groundwater level in monthi (m);

h(i – 1) = Groundwater level in previous month (m);

F = Fraction;

Pi = Precipitation in monthi (m);

C = Cutoff monthly rainfall, below which no recharge occurs (m);

S = Specific yield; Ii = Inflow to the aquifer during monthi (m3); Oi = Outflow to the aquifer during monthi (m3); A = Area (m2); and Qi = Withdrawal (pumping) from the aquifer during monthi (m3). Note: Ri = effective monthly recharge (m) is represented as F(Pi-C)

The CRD technique is a lumped parameter method. That is, the hydrological status of the aquifer is integrated into a composite hydrograph that simulates saturated volume fluctuations derived from water level records in the studied area. For the purposes of this assessment it is assumed that groundwater levels in observation bore (P10680) are representative an aquifer area of about 10 km2. The method ideally requires monthly

12 of 30


water level, abstraction and rainfall data for the simulated period. The relationship is implemented into a spreadsheet model that allows for optimisation of input parameters by matching observed water levels with computed hi. Due to the frequency of observations made at P10680, quite a few measurements had to be duplicated or interpolated for the analysis. Given the constraints with this dataset, this should not be considered a definitive assessment, but it should yield an order of magnitude estimate of recharge and storage. Given that no known large scale groundwater abstraction is occurring in the region, it was assumed that pumping affects in the analysis were negligable, and thus set to zero. Drawing 13 shows probably the best match between the CRD-modelled and observed water levels, and the parameters which were required to achieve the greatest amount of correlation. Based on the analysis, it was possible to achieve an approximate fit for the data with recharge rates of 0.05% to 0.1% of rainfall, but towards the higher end of recharge (ie 0.1%), the calibration was not as robust. For this reason, the following parameters are considered to be the best estimate:

Recharge – 0.05 % of rainfall; and

Specific Yield – 0.002 (ie 0.2%). The recharge estimate of 0.05% should be considered as an estimate for the more diffuse recharge occurring across the region. Previous investigations in the Blackwater / Curragh region indicate that Permian fractured rock aquifers are recharged by incident rainfall while PB (2003) contended that recharge of the Rangal Coal Measures at Curragh North may occur in part via seepage from the Mackenzie River into subcropping Permian strata. The analysis completed at South Walker Creek shows that recharge of the Permian strata is very limited, and is probably confined to the region along the Carborough Range where the water is initially sourced. 7.4 Groundwater Quality

Groundwater quality data associated with the Tertiary / Quaternary alluvium aquifer are limited. The electrical conductivity (EC) values reported for Kiss’ Bore are generally between 1,400 μS/cm and 1,800 μS/cm which indicates that the Tertiary aquifer has pockets of reasonable quality water held within the alluvium. Kiss’ Bore supplies stock water to the landowners (Baulch’s) grazing areas to the west and east of Kemmis Pit. IESA (2003) indicates that the Tertiary units were dry to the south of Walker Pit at monitoring bores P10672 and P10680 indicating that groundwater occurrence in this unit is not spatially continuous and concluded that the occurrence of Tertiary groundwater resources is limited to aquifers associated with Walker Creek upstream of the mine (GHD, 2012). Groundwater quality associated with the Permian sedimentary layers is described as highly saline and unsuitable for stock watering or domestic use (EC >15,000 μS/cm and pH generally ranging from 6 to 7) (IESA 2003). Groundwater in excess of ~12,000 µS/cm EC is not considered suitable for stock watering.

13 of 30


BMA (2009) defined a 90th percentile conductivity value of 23,620 μS/cm for the trigger level for conductivity in Permian groundwaters. The current trigger value for pH has been set at 6.5. New trigger levels need to be set as per the current EA. Drawing 14 shows the spread of all water quality data, across all aquifer units. It can be observed from this drawing that there have been no regional samples collected near the proposed Kemmis II Pit. Regionally, there are pockets of water quality information which are likely associated with other mine sites or from fresher groundwaters sourced from pockets of alluvium. Typically, most samples collected to the east of Carborough Range are considered brackish to saline. Water chemistry plots from the SWC bores are presented in Appendix B, and will be discussed in further detail in the DP 2013 SWC annual groundwater review (in prep). 7.5 Groundwater Utilisation

The DNRM groundwater database search was carried out to assess the level of groundwater use around the South Walker Creek mine site, and to obtain additional information concerning the types of aquifers within the area. The DNRM groundwater database search identified 197 registered bores within a 30 km radius of SWC Mine (Drawing 8). The SWC Mine occurs within the Isaac Connors Groundwater Management Area (GMA) where any works for taking or interfering with water for purposes other than stock or domestic use (other than small diameter groundwater monitoring bores) are assessable activities and require a development permit. While water bore drillers are required to submit drill logs to the Department regardless of whether they are within a groundwater management area or not, this has not always been the case and there may be bores that have been drilled in the past which have not been registered in the DNRM groundwater database. Summary details of all registered bores identified in the search of the database are provided in Table 2. Of the 197 registered bores:

37 have been completed for exploration, investigations or monitoring;

19 bores were purportedly installed for water supply. Of these 19, the closest bore is located some 22 km from the proposed Kemmis II Pit; and

141 do not have a listed purpose.

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Table 2: Summary of DNRM Registered Bores

Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)

23683 610,002 7,583,535 NR NR NR NR NR NR NR 23686 609,746 7,585,353 NR NR NR NR NR NR NR 23745 609,749 7,585,722 NR NR NR NR NR NR NR 23755 610,038 7,585,966 NR NR NR NR NR NR NR 23758 609,636 7,585,969 NR NR NR NR NR NR NR 23843 610,179 7,585,719 NR NR NR NR NR NR NR

23951 642,130 7,575,318 NR NR NR NR NR Petroleum

or Gas Exploration

NR


or Gas Exploration

NR

46582 636,558 7,583,562 250 NR Blackwater Group NR NR NR 1,300

46847 627,923 7,623,002 22 NR Rewan Group 1.9 4.5 NR NR


46849 626,010 7,623,714 61 NR NR NR NR NR NR 46850 626,023 7,630,315 37 NR NR NR NR NR NR

46916 636,566 7,583,455 58 NR Clematis Group 1.5 3 NR NR

63091 668,946 7,588,564 46 NR NR NR NR NR NR 63092 670,392 7,587,626 46 NR NR NR NR NR NR 63094 669,210 7,583,676 52 NR NR 0.9 40.8 NR NR 63095 671,224 7,590,283 27 NR NR 1.5 14.6 NR NR 63179 668,322 7,593,397 23 NR NR NR NR NR NR 63592 669,965 7,613,805 18 NR NR NR 7.6 NR NR

81848 640,109 7,580,113 180 NR Upper

Bowen Coal Measures

NR 14.8 Mineral or

Coal Exploration

NR

81908 619,562 7,588,213 75 NR Rewan Group 19.0 NR Water

Supply NR

81909 620,090 7,573,319 9 NR Rewan Group 5.3 17.2 NR 2,690 -

5,670

85078 639,863 7,579,577 45 NR Upper Bowen Coal 3.2 29.8 NR NR

85236 630,975 7,579,719 NR NR NR NR NR NR NR

85403 650,860 7,593,075 4 NR Bee Creek Alluvium 0.5 NR NR NR


or Gas Exploration

NR


or Gas Exploration

NR

100083 622,605 7,570,007 NR NR NR NR NR NR NR


or Gas Exploration

NR


or Gas Exploration

NR


or Gas Exploration

NR

100088 645,871 7,592,045 NR NR NR NR NR Petroleum NR

15 of 30


Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)


or Gas Exploration

NR


or Gas Exploration

NR


or Gas Exploration

NR

100120 629,268 7,570,968 NR NR NR NR NR NR NR 100121 629,296 7,570,907 NR NR NR NR NR NR NR


105435 616,878 7,570,581 90 NR Blackwater

Group - Undiff.

NR 23 NR NR

105676 622,312 7,577,795 41 36 - 41 Tertiary - Undefined 6.0 13.92 Water

Supply 1,243

105677 622,136 7,573,306 67 62 - 67 Tertiary - Undefined 7.3 25.14 NR 1,055

105678 621,020 7,580,303 44 38 - 43 Basalt 3.9 18.35 Water Supply 2,640

105838 642,816 7,625,689 32 NR Blackwater Group NR 13.72 Water

Supply NR

131000 621,888 7,578,276 73 67 - 72 Tertiary - Undefined 6.2 21 Water

Supply 1,866


Supply 1,732

131002 621,997 7,574,302 63 57 - 62 Tertiary - Undefined 6.0 27 NR 1,022


Supply 1,362

131217 659,420 7,623,040 NR NR NR NR NR Water Supply NR

131218 657,953 7,622,609 17 NR Blenheim Formation 2.1 10 Water

Supply Potable




131612 620,803 7,582,641 105 NR Blackwater

Group - Undiff.

5.0 17.91 Water Supply 2,900

131613 620,721 7,582,804 106 NR Blackwater

Group - Undiff.

3.0 12 Water Supply 1,680

131614 620,575 7,583,096 106 NR Blackwater

Group - Undiff.

1.0 32.64 Water Supply 1,080

131615 620,661 7,582,919 104 NR Blackwater

Group - Undiff.

4.0 38.92 Water Supply 3,660

141123 663,307 7,604,980 37 NR NR 0.6 10 Water Supply 1,800

141124 667,132 7,607,940 31 NR NR NR NR Water Supply NR

141125 667,213 7,608,062 15 NR NR NR NR Water Supply NR

141159 622,211 7,577,781 38 NR Basalt 3.7 12 NR Potable 141165 622,260 7,577,783 38 NR Basalt 3.2 12.61 NR Potable

16 of 30


Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)

141168 620,595 7,582,651 32 NR NR 5.0 13.4 Sub-

artesian Monitoring

3,200

141170 620,826 7,595,643 138 NR

Rewan Formation & Rangal Coal

Measures

8.2 40 Sub-

artesian Monitoring?

Brackish

141190 622,311 7,577,787 42 NR Basalt 9.5 13.35 NR Potable 141269 622,359 7,577,792 43 NR Basalt 2.8 13.67 NR Potable 141291 622,405 7,577,797 41 NR Basalt 4.1 13.52 NR Potable

141292 622,798 7,577,839 120 NR Rewan Group 4.4 10.99 NR Saline

141313 623,736 7,577,830 55 NR Rewan Group 1.3 23.8 NR Potable


141343 621,768 7,577,771 61 NR NR NR NR NR NR 141381 622,008 7,576,801 33 NR Basalt 0.1 14.17 NR Potable 141417 622,299 7,577,301 30 NR Basalt 0.5 11.15 NR Potable 141418 622,393 7,577,303 26 NR Basalt 0.1 10.42 NR Brackish 141421 622,199 7,577,302 35 NR Basalt 6.3 12.1 NR Potable 141422 621,968 7,576,801 31 NR Basalt 0.2 12.84 NR Potable 141429 622,198 7,576,304 34 NR Basalt 0.8 14.59 NR Potable 141441 622,399 7,575,299 62 NR Basalt 1.3 19.87 NR Potable 141455 622,404 7,575,801 64 NR Basalt 1.8 14.5 NR Potable 141456 622,097 7,574,303 58 NR Basalt 1.9 26.99 NR Potable 141457 621,946 7,573,298 55 NR Basalt 2.6 20.14 NR Potable 141458 622,102 7,573,101 66 NR Basalt 2.9 29.92 NR Potable 141545 660,325 7,610,110 36 NR NR 1.2 6 NR Potable 141546 664,471 7,601,389 42 NR NR NR 10 NR Brackish 141547 658,909 7,623,526 20 NR NR 3.9 10 NR Potable 141561 623,516 7,571,386 25 19 - 25 NR NR NR NR NR 141562 624,540 7,571,500 25 19 - 25 NR NR 21.4 NR NR 141563 624,355 7,572,070 25 NR NR NR NR NR NR 141564 624,207 7,572,428 25 NR NR NR NR NR NR 141565 625,902 7,572,509 25 NR NR 0.01 14.2 NR Brackish 141566 628,232 7,571,839 25 NR NR NR NR NR NR 141567 631,862 7,569,819 25 NR NR NR NR NR NR 141568 631,032 7,570,989 25 NR NR 0.01 24.3 NR Brackish 141605 622,186 7,574,781 44 NR Basalt 1.8 10.96 NR Brackish

141664 649,432 7,584,695 101 92 - 98 & 101 - 104

Blackwater Group 0.6 49.23

Sub-artesian

Monitoring 14,260

141665 649,491 7,584,642 44 36 - 43 Blackwater Group NR 39.08

Sub-artesian

Monitoring NR

141666 648,307 7,584,036 119 113 - 119 Blackwater Group 1.0 48.9

Sub-artesian

Monitoring 12,800

141667 648,307 7,583,794 21 11 - 14 & 18 - 21 NR NR NR

Sub-artesian

Monitoring NR

141668 650,852 7,584,036 109 103 - 106 & 109 -

112

Blackwater Group 0.1 112

Sub-artesian

Monitoring

13,970

17 of 30


Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)

141669 648,986 7,583,197 73 67 - 70 & 73 - 76

Blackwater Group 2.2 48.45

Sub-artesian

Monitoring 14,840

141670 648,986 7,583,197 43 37 - 43 Blackwater Group 0.1 40.28 NR 14,570

141671 649,810 7,582,855 101 86 - 89 & 95 - 101

Blackwater Group 0.1 55

Sub-artesian

Monitoring 20,430

141672 649,810 7,582,855 39 33 - 39 NR NR NR Sub-

artesian Monitoring

NR


Sub-artesian

Monitoring 16,420

141674 651,605 7,582,574 27 21 - 27 NR NR NR Sub-

artesian Monitoring

NR


Sub-artesian

Monitoring 16,420

141676 651,820 7,580,980 26 20 - 26 Blackwater Group NR 18.6

Sub-artesian

Monitoring NR

141696 621,998 7,574,807 45 NR Basalt 1.7 11.69 NR Brackish 141718 670,868 7,608,326 23 NR NR 0.9 12 NR Salt 141766 660,798 7,598,252 37 NR NR NR NR NR NR 141767 661,574 7,600,988 31 NR NR NR NR NR NR 141807 621,693 7,573,807 53 NR Basalt 3.5 20.15 NR Potable 141808 621,794 7,572,499 30 NR Basalt 3.5 14.15 NR Potable 141809 621,748 7,571,997 23 NR NR NR NR NR NR 141812 620,901 7,582,285 60 NR Basalt NR 13.5 NR NR 141813 621,254 7,581,300 24 NR NR NR NR NR NR 141864 621,978 7,572,901 42 NR Basalt 3.6 20.66 NR Potable 141865 621,974 7,572,779 32 NR Basalt 4.2 16.68 NR Potable

141947 620,875 7,595,650 140 NR

Rewan Formation & Rangal Coal

Measures

0.8 46 Sub-

artesian Monitoring?

Brackish

141981 622,210 7,573,376 55 NR Basalt NR 27 NR Fresh

141982 622,980 7,577,822 59 NR Rewan Group 39.4 15 NR Saline




141986 622,452 7,577,802 37 NR Basalt 0.2 14 NR Brackish 141987 622,505 7,577,805 27 NR Basalt 6.3 13 NR Potable?

141988 622,551 7,577,806 60 NR Rewan Group 0.5 17.36 NR Brackish



141991 622,691 7,577,816 60 NR Rewan Group 0.3 12.64 NR Brackish


18 of 30


Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)


141994 622,067 7,577,769 26 NR NR NR NR NR NR 141995 622,017 7,577,764 31 NR Basalt 1.0 10.93 NR Potable 141996 621,968 7,577,763 29 NR Basalt 0.4 10.38 NR Potable 141997 622,118 7,577,774 34 NR Basalt 1.9 11.28 NR Potable 141998 622,167 7,577,778 41 NR Basalt 3.4 11.61 NR Potable

162000 620,779 7,582,851 120 NR Rangal Coal Measures 1.4 25 NR 4,620

162001 620,709 7,582,972 116 NR Rangal Coal Measures 13.2 24.39 NR 1,320

162002 620,597 7,582,672 42 NR Fort Cooper

Coal Measures

4.0 12.7 NR 2,940

162003 620,521 7,582,801 40 NR Fort Cooper

Coal Measures

1.5 13.34 NR 1,412

162004 620,370 7,583,006 30 NR Fort Cooper

Coal Measures

0.04 20 NR 2,491

162005 620,860 7,582,690 112 NR Rewan Group 13.9 19.63 NR 4,740

162006 620,784 7,582,835 109 NR Rewan Group 1.9 21.73 NR 1,174

162007 620,708 7,582,978 105 NR Rangal Coal Measures 11.2 20.8 NR 1,110

162008 620,463 7,583,047 58 NR Fort Cooper

Coal Measures

2.1 14.18 NR 1,100

162009 620,370 7,583,003 20 NR NR NR NR NR 1,240 162010 620,520 7,582,806 31 NR NR NR NR NR 2,900 162011 621,951 7,572,589 32 NR Basalt 0.9 12.27 NR 2,620 162012 621,900 7,572,494 26 NR NR NR NR NR NR 162013 621,998 7,572,002 44 NR Basalt 1.3 17.2 NR Brackish 162014 621,993 7,572,501 25 NR Basalt 0.01 16.22 NR NR 162015 621,796 7,572,381 17 NR NR NR NR NR NR 162016 621,754 7,572,407 25 NR NR NR NR NR NR 162017 621,699 7,572,436 33 NR Basalt 0.4 14.92 NR Brackish 162018 620,803 7,581,793 19 NR Basalt 2.2 10.55 NR Potable 162019 621,876 7,578,278 73 NR Basalt 3.1 19.82 NR Brackish 162020 622,073 7,573,245 61 NR Basalt 2.9 24.77 NR Potable 162021 621,103 7,579,809 42 NR Basalt 2.8 24.36 NR Brackish 162022 621,404 7,579,305 43 NR Basalt 1.2 12.75 NR Potable 162023 621,512 7,578,807 74 NR Basalt 1.9 32 NR Brackish 162024 621,028 7,580,202 35 NR Basalt 0.1 18.63 NR Brackish 162025 621,036 7,580,333 49 NR Basalt 3.4 18.5 NR Brackish 162026 622,311 7,577,879 45 NR Basalt 1.3 18 NR Potable 162027 622,312 7,577,815 42 NR Basalt 4.8 16 NR Potable 162028 622,165 7,573,319 83 NR Basalt 9.4 27 NR Potable 162029 621,026 7,580,398 49 NR Basalt 0.2 20 NR Brackish 162030 622,313 7,577,692 39 NR Basalt 8.4 13 NR Brackish 162031 622,046 7,577,326 34 NR Basalt 0.5 12 NR Potable 162032 622,082 7,577,383 36 NR Basalt 5.2 10.6 NR Brackish 162033 622,020 7,577,200 33 NR Basalt 1.5 12.13 NR Potable 162034 620,705 7,582,520 61 NR Rangal Coal 0.4 16.57 NR NR

19 of 30


Bore

RN

Easting

(GDA94)

Northing

(GDA94)

Total

Depth

(m)

Screened

Interval

(m)

Aquifer /

Formation

Yield

(L/s)

SWL

(mbGL) Use

Quality

(EC -

µS/cm)

162035 620,678 7,582,528 51 NR NR NR NR NR NR

162036 620,411 7,582,854 14 NR Fort Cooper

Coal Measures

0.01 9.56 NR NR

162037 620,481 7,582,701 15 NR Fort Cooper

Coal Measures

0.04 10.2 NR NR

162038 620,562 7,582,547 17 NR Fort Cooper

Coal Measures

0.04 12.04 NR NR

162039 620,459 7,583,039 65 NR Fort Cooper

Coal Measures

1.6 16.5 NR NR

162040 622,322 7,577,819 68 NR NR NR NR NR NR


162042 621,025 7,580,332 83 NR Basalt & Rewan Group

3.1 NR NR 1830

13040108 656,268 7,609,508 NR NR NR NR NR NR NR 13040109 655,634 7,609,391 NR NR NR NR NR NR NR 13040110 654,973 7,609,398 NR NR NR NR NR NR NR 13040111 654,482 7,609,249 NR NR NR NR NR NR NR

13040112 663,285 7,580,467 26 22 - 25 Bee Creek Alluvium NR NR

Sub-artesian

Monitoring / Water

Resource Investigation

NR

13040113 663,218 7,580,855 NR NR NR NR NR NR NR 13040114 663,165 7,581,064 NR NR NR NR NR NR NR 13040115 663,227 7,581,356 NR NR NR NR NR NR NR

13040307 661,844 7,596,903 120 NR Volcanics - Undiff. 12.0 NR

Water Resource

Investigation

1,480 - 1,690


Water Resource

Investigation

4,460 - 4,750


Water Resource

Investigation 940


Water Resource

Investigation 1,677

13040312 659,201 7,596,389 24 NR Blackwater Group 0.6 NR

Water Resource

Investigation

5,400 - 5,500


Water Resource

Investigation 771


Water Resource

Investigation

2,700 - 2,810


Water Resource

Investigation

3,980 - 4,160

13040316 665,675 7,613,373 200 NR Leura Volcanics 1.6 NR

Water Resource

Inv 1,056

Notes: NR – No record;

20 of 30


Based on the limited information available, it does not appear that groundwater in the Permian sediments is used for extractive purposes in the local area. The search results show that there are no significant groundwater users within the vicinity of Kemmis II Mine. This is probably due to the high salinity of groundwater in the Permian sediments (based on the available data) that would limit the beneficial uses of this aquifer. Similarly, only 5 bores have been flagged as being for water supply purposes of the bores completed in the Tertiary or Basalt units. Furthermore, of these 5 bores, the closest bore is some 27 km from the proposed pit (and located to the west of Carborough range) which illustrates that the Tertiary unit is poorly developed in this area. The data indicate an average bore yield of ~3 L/s, although this is made artificially high due to a large number of bores on the western side of Carborough Range. Groundwater levels range from ~3 mbGL to 112 mbGL, with an average of ~20 mbGL. 7.6 Conceptual Hydrogeological Model Cross Section

Detailed geological model layer data obtained from BMC was used in conjunction with the composite piezometric surface, bore details and proposed Kemmis II pit shell to construct a hydrogeological cross section through the proposed site. Drawings 15 to 18 show the following:

Isopachs of the MT1, MT2 and MB2 coal seams

Location of hydrogeological cross section

Thicknesses of the Tertiary sediments and associated weathered zone

Hydraulic gradient at the site and direction of groundwater flow

Location of seam sub-crop

21 of 30


8. Mine Impact Assessment

8.1 Estimates of Mine Inflows

Douglas Partners has completed a preliminary impact assessment on the local groundwater system by running an analytical model to simulate groundwater flows into the proposed pit over the course of the mines life. The model is able to predict transient discharge rates and the extent of drawdown (ro) and assumes a circular pit in an unconfined porous media aquifer which is homogeneous and unlimited in extent. The analytical model is based on Thiem and Dupuit-Forchheimer equations where by the mine is represented by an equivalent large diameter well. Pit inflow rates are calculated after every six months. Accordingly, a number of assumptions were made in order to model these impacts. These assumptions are listed below:

The mine life is operated over 10 years with the final 10 year Kemmis II footprint being the final pit void, which on average is 500 m wide (note that the model assumes an open void and does not account for backfilling with spoil which maximises the predicted impact). The surface area of the pit (1,671,941 m2) equates to a circular radius of 750 m and was tested as a sensitivity analysis during the analytical modelling. The results did not vary significantly, and as such the final radius adopted was r = 500 m;

Recharge estimated at the mine site by DP of 0.05% is negligible within the proposed mine area and is hence not included in the estimate;

In the absence of a detailed mine plan, the pit floor is assumed to advance at 8.3 m per year over the 10 years, with the mine becoming ‘wet’ through the final 6 years as the mine progresses from 225 mAHD down to a final operating level of 175.2 mAHD; and

The hydraulic conductivity adopted represents a bulk hydraulic conductivity of the entire mine, and as such should represent the Permian low permeability rockmass, and not the higher permeability seams. Given the Permian strata is likely to be 1-2 orders of magnitude lower than the coal seams (which have a hydraulic conductivity of ~0.1 m/d) a starting value of 0.01 m/d was adopted. As the proposed pit does not intersect the mapped Tertiary sediments, this simplification is justified.

Due to the range of uncertainty with the hydraulic parameters required in the analytical model, DP conducted a sensitivity analysis with the hydraulic parameters, to estimate both minimum and maximum values for pit inflows and radius of influence of the mine. An Sy value of 0.1% was adopted as a starting value based on the estimate of 0.2% calculated from observation bore P10680. Tables 3 and 4 present the calculated mine inflow and radius of influence under the various scenarios.

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Table 3: Summary of Calculated Mine Inflows (L/s) for Kemmis II Mine

Hydraulic Conductivity Sy = 0.1% Sy = 0.5%

0.04 m/d 6.3 9.7

0.02 m/d 3.7 6.3

0.01 m/d 2.3 10.3 Table 4: Summary of Calculated Radius of Influence (m) for Kemmis II Mine

Hydraulic Conductivity Sy = 0.1% Sy = 0.5%

0.04 m/d 4,965 2,220

0.02 m/d 3,511 1,570

0.01 m/d 2,482 1,110

As Table 4 shows, the calculated radius of influence of the Kemmis II Pit varies between 2482 – 4965 metres. Given that the existing Toolah Pit is of a similar depth to the proposed Kemmis II Pit, and only slight drawdown can be observed at P10672 (and not P10680), then it seems more likely that the adopted value for specific yield of 0.1% is the most appropriate value for this model. In the case that specific yield is closer to 0.1%, the most likely mine inflow rates to the Kemmis II Pit are of the order of 2.3 L/s, and up to a maximum of 6.3 L/s as the bulk hydraulic conductivity is increased. Drawing 19 shows the predicted mine inflows resulting from the analytical modelling against time as the pit advances. Drawing 20 shows the volumes of mine water removed from the existing SWC mine, as compared to the volumes of rainfall (not including surface runoff) which report to the pit area. It can be observed from this graph that, through the dry periods when no rain is experienced at site, that dewatering is not required. For example, during December 2012, which was relatively dry in terms of rainfall, the total amount pumped out of Kemmis I pit was 1 ML (on 30th December). If it is assumed that the volume of water pumped from the Kemmis I pit was entirely sourced from mine inflows (that is groundwater inflow and neglecting the effects of evaporation) then the average inflow rate to the mine over the period since previous pumping occurred (40 days) would be approximately 0.3 L/s. The data presented in Drawing 20 supports the analytical modelling results for the proposed Kemmis II pit. 8.2 Impacts to Groundwater Levels and Quality

Based on the analytical modelling, impacts to local groundwater levels are likely to be focussed around the Kemmis II Pit. Due to the low permeability rockmass, the cone of depression does not propagate over a wide area. Hydraulic gradients near to the pit wall are likely to be sub-vertical and extend out to a radius of influence of the order of 2.5 km. It should be noted that this radius is calculated from the centre of the pit, and therefore the pit will likely impact the groundwater system within 2.3 km from the pit wall.

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One of the concerns that has been raised with the proposed Kemmis II Pit, is what impact it might have on the QR Farm Dam which is located approximately 1 km to the northeast of the proposed mine site (shown on Drawing 2) Given the QR Farm Dam is not down-gradient of the proposed mine, any impact would need to be associated with increased downward leakage through the Permian strata. Given the low mine inflow rates predicted in the analytical model, this is not considered likely to occur unless significant fracturing existed in the rockmass. Groundwater vulnerability has been defined in the ANZECC National Water Quality Management Strategy (ANZECC / ARMCANZ, 1995) as a relative evaluation of the potential exposure of a groundwater resource and its beneficial use, to contamination from planned and unplanned sources. The concept of vulnerability is based upon an assumption that the physical environment can provide some degree of protection from contamination through natural attenuation processes. The vulnerability assessment is a qualitative assessment based upon the nature of the hydrogeological regime, as well as the thickness and nature of the unsaturated zone overlying an aquifer. For example, a shallow unconfined aquifer with a permeable unsaturated zone would be highly vulnerable to surface contamination, whereas a deep confined aquifer would have a low vulnerability. The groundwater systems present at South Walker Creek Mine comprise a confined aquifer in the Permian strata, and an unconfined aquifer in the alluvium associated with Walker Creek and Carborough Creek. Groundwater in Permian strata is considered to have a very low vulnerability to contamination from mining and coal processing at SWC due to the following reasons:

The confined nature of the aquifer;

Depth to groundwater is considerable (greater than 20 m, on average);

The confining strata are comprised mainly siltstone and shale, which have low permeability; and

Recharge is very low, as is evident from groundwater level monitoring and the recharge estimate completed during this study.

Groundwater in pockets of alluvium at South Walker Creek is considered to have a greater vulnerability to contamination than the fractured rock aquifers in Permian strata (due to occurring at shallow depths); however, the potential for contamination of the alluvial aquifer is also classified as low, based on the following:

Surface geological mapping shows that the proposed pit does not intersect the Tertiary sediments;

Impacts to the Tertiary groundwater system would likely involve induced downward leakage towards the mine, meaning that groundwater flow tends towards mine inflow (the mine does not become a source); and

The majority of mining activity occurs far below the base of the Tertiary unit, which effectively separates the hazard from the aquifer.

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Another factor to be considered in assessing the potential for groundwater contamination is the fact that groundwater in the vicinity of the mine is not used by land holders because of low bore yields and absence of aquifer continuity, and high (natural) groundwater salinity. The potential for groundwater contamination at the proposed South Walker Creek Kemmis II Pit is characterised as low to very low. 8.3 Groundwater Dependent Ecosystems (GDE’s)

As part of assessing the likely impact to groundwater dependent ecosystems, DP downloaded all available datasets from the Australian Bureau of Meteorolgy’s Atlas of Groundwater Dependent Ecosystems (BOM, 2013) within a 5 km radius of the proposed Kemmis II Pit. Available data were downloaded in GIS format, and plotted to confirm the locations of any identified features. All features identified belong to the Vegetation category, and the potential for groundwater interaction is shown on Drawing 21. Based on the data available summarised in Table 5, it is believed that none of the identified records represent inflow dependent ecosystems (IDEs). Regardless of whether the GDE’s are inflow dependent or not, the estimated impacts caused through the excavation of the Kemmis II Pit are considered to be very low. This is because the calculated volumes of groundwater reporting to the pit are low and the GDE’s considered of high potential for groundwater interaction occur predominantly beyond the nominated radius of influence of the pit. Table 5: Summary of Identified Groundwater Dependent Ecosystems

UFI ECOTYPE BASIN LAND

TYPE

GW

FLOW LAND USE GWDEP

2071077 Vegetation FITZROY

RIVER Low

Lying Regional Livestock grazing Moderate potential for GW interaction


RIVER Low

Lying Intermediate Livestock grazing Moderate potential for GW interaction


RIVER Low

Lying Regional Dryland agriculture Low potential for GW interaction


RIVER Low

Lying Regional Livestock grazing Low potential for GW interaction


RIVER Low

Lying Regional Livestock grazing High potential for GW interaction


RIVER Low

Lying Intermediate Livestock grazing High potential for GW interaction


RIVER Slope Intermediate Dryland agriculture Low potential for GW interaction


RIVER Slope Intermediate Livestock grazing Moderate potential for GW interaction


RIVER Low


2071646 Vegetation FITZROY Low Lie Regional Livestock grazing High potential for GW interaction

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UFI ECOTYPE BASIN LAND

TYPE

GW

FLOW LAND USE GWDEP


RIVER Low



RIVER Low



RIVER Low



RIVER Low



RIVER Low

Lying Intermediate Livestock grazing Low potential for GW interaction


RIVER Slope Local Livestock grazing Moderate potential for GW interaction


RIVER Low



RIVER Low



RIVER Low



RIVER Low

Lying Regional Livestock grazing Low potential for GW interaction


RIVER Low



RIVER Low



RIVER Low


8.4 Recommendations

Notwithstanding the assessed low potential for groundwater contamination at the proposed Kemmis II Pit, there is a need to augment the current monitoring system in order to better characterise groundwater quality and groundwater level behaviour. Given that there are no dedicated monitoring bores completed in the Tertiary / Quaternary aquifer, this should be considered a priority. The other major missing component from a monitoring perspective is a background bore which should be located up-gradient of the site. An observation bore strategically located in the north to north west may provide background data for the existing operations, as well as for future monitoring of the proposed pit, and QR Farm dam. With consideration given to the the findings of the 2013 Annual Groundwater Review, as well as a potential future expansion of the the Mulgrave pit, Douglas Partners recommends that 7 new monitoring sites are completed. These sites are shown in Drawing 22, together with the purpose of each site and approximate site coordinates.

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This augmentation of the groundwater monitoring system at South Walker Creek Mine is recommended and will add significant value to the historic monitoring which has already been completed. 9. Summary

Hydrogeological and other data have been collated to compile a Conceptual Hydrogeological Model for the South Walker Creek Mine, proposed Kemmis II Pit and the surrounding region. A hydrogeological cross section was prepared to highlight the main features of the CHM and is shown in Drawing 18. The CHM developed by DP recognises two groundwater systems at the South Walker Creek operations:

Shallow aquifer within the Tertiary to Quaternary sediments; and

Deeper aquifer within the underlying Permian to Triassic Strata. Strata of the underlying Permian to Triassic strata host groundwater resources, primarily within coal seams which are likely to be at least an order of magnitude higher in permeability than the surrounding strata. The Permian groundwaters:

Are characterised by low permeability and storage where water is predominantly stored and transmitted by secondary porosity features such as fractures, faults, discontinuities of the rock mass, and though the coal seam and cleat;

Are confined by the lower permeability host rock matrix;

Contain poor quality (moderately saline) groundwater;

Are poorly recharged due to low permeability confining strata;

Are not widely utilised due to quality and yield constraints;

Have been classified historically as a discontinuous and low value resource in the vicinity of a high impact activity, and;

Are not at high risk of contamination from mining and mining related activities. The other potential source of groundwater can be found within the Tertiary to Quaternary sediments associated with Walker and Carborough Creeks. These sediments are generally quite thin and poorly developed. The alluvial aquifer is characterised by:

Pockets of reasonable quality groundwater with low yields;

Discontinuous extent;

Moderate permeability and storage; and

Limited utilisation.

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Groundwater levels in the alluvial aquifer are not known. Groundwater in pockets of alluvium at South Walker Creek is considered to have a greater vulnerability to contamination than the fractured rock aquifers in Permian strata; however, the potential for contamination of the alluvial aquifer is classified as low, based on the following:

Surface geological mapping shows that the proposed pit does not intersect the Tertiary sediments;

Impacts to the Tertiary groundwater system would likely involve induced downward leakage towards the mine, meaning that groundwater flow tends towards mine inflow (the mine does not become a source); and

The majority of mining activity occurs far below the base of the Tertiary unit, which effectively separates the hazard from the aquifer.

Notwithstanding the low potential for groundwater contamination from the operations at SWC, recommendations are made for increasing the coverage and monitoring capacity of the groundwater monitoring system due to the paucity of current data available. Douglas Partners has recommended 7 sites be selected for the monitoring augmentation.

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10. Limitations

Douglas Partners (DP) has prepared this report for a project at South Walker Creek Mine, via Nebo, Central Queensland, in accordance with DP's proposal dated 5 July 2013 and acceptance received from Mr Tyson Smalley of BHP Mitsui Coal on 8 July 2013. The report is provided for the exclusive use of BHP Mitsui Coal South Walker Creek for this project only and for the purpose(s) described in the report. It should not be used for other projects or by a third party. In preparing this report DP has necessarily relied upon information provided by the client and/or their agents. The results provided in the report are indicative of the sub-surface conditions only at the specific sampling or testing locations, and then only to the depths investigated and at the time the work was carried out. Sub-surface conditions can change abruptly due to variable geological processes and also as a result of anthropogenic influences. Such changes may occur after field testing has been completed. DP's advice is based upon the conditions encountered during this investigation. The accuracy of the advice provided by DP in this report may be limited by undetected variations in ground conditions between sampling locations. The advice may also be limited by budget constraints imposed by others or by site accessibility. This report must be read in conjunction with all of the attached notes and should be kept in its entirety without separation of individual pages or sections. DP cannot be held responsible for interpretations or conclusions made by others unless they are supported by an expressed statement, interpretation, outcome or conclusion given in this report.

Douglas Partners Pty Ltd

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11. References

AUSTRALIAN BUREAU OF METEOROLOGY (BOM), 2013: Atlas of Groundwater Dependent Ecosystems. Water Data. Accessed 22 August 2013, <http://www.bom.gov.au/water/groundwater/gde/map.shtml>.

AUSTRALASIAN GROUNDWATER & ENVIRONMENTAL CONSULTANTS PTY LTD (AG&E),

2010: Report on South Walker Creek Mine: Annual Groundwater Assessment. Prepared for BHP Mitsui Coal Operations Pty Ltd. Project No G1525. October 2010.

ANZECC / ARMCANZ, 1995: National Water Quality Management Strategy: Guidelines for Groundwater Protection in Australia. September 1995.

BHP BILLITON MITSUI ALLIANCE (BMA), 2009: South Walker Creek Mine Annual Groundwater

Program Review. 2009.

GHD, 2012: South Walker Creek Mine: Annual Groundwater Review. Report prepared for BHP Mitsui Coal Pty Ltd. Project 42/17499. September 2012.

HAIR, I.D., 1987: Hydrogeology of Coal Seams at Curragh, Central Queensland. Geological Survey of Queensland Record 1987/20. May 1987. Ref: E205.

INTEGRATED ENVIRONMENTAL SERVICES AUSTRALIA (IESA), 2003: Report on Groundwater

Monitoring and Piezometer Installation South Walker Creek Mine. June 2003. KAMENAR AND ASSOCIATES PTY LTD, 2013: Permeability Testing and Analysis of Coal Seam

MB2 – Confidential report on South Walker Creek Coal Project. January 2013.

MULLER, P.J., & HAIR, I.D., 1980: Curragh Coal Aquifer testing – Report on Hydrogeological Investigations. Geological Survey of Queensland Record 1980/39. October 1980. Ref: E205.

MULLER, P.J., NGUYEN, V.V., HAIR, I.D., NGUYEN, V.U., & MALLETT, C.W., 1983:

Hydrogeological studies and their significance in the Rangal Coal Measures, Curragh, Central Bowen Basin, Queensland. CSIRO Institute of Energy and Earth Resources, Division of Geomechanics. Report 36.

PARSONS BRINKERHOFF PTY LTD., 2003: Curragh North Coal Mine - Hydrology, Flooding and

Groundwater Report. Project No. 2132105A-PR001Ebt (Appendix G of Curragh North Mine Environmental Impact Statement). August 2003.

QUEENSLAND DEPARTMENT OF SCIENCE, INFORMATION TECHNOLOGY, INNOVATION

ANDTHE ARTS (SITIA), 2013: SILO Climate Data. The Long Paddock. Last updated 13 May, 2013. Accessed 11 June 2013, < http://www.longpaddock.qld.gov.au/silo/>.

UNITED STATES GEOLOGICAL SURVEY (USGS), 2013: Earth Explorer. USGS: Science for a

Changing World. Last updated 18 July 2013. Accessed 15 August 2013, < http://earthexplorer.usgs.gov/>.

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WENZEL, L.K., 1936: Several Methods of Studying of Groundwater Levels. Transactions American Geophysical Union, Volume 17.

Drawings

Drawing 1: Location of Kemmis II Pit Drawing 2: Site Layout – South Walker Creek Mine Drawing 3: Regional Topography and Surface Drainage Drawing 4: Long Term Annual Rainfall Trends Drawing 5: Long Term Monthly Rainfall and Evaporation Drawing 6: Regional Geology Drawing 7: Waters Encountered During Exploration Drawing 8: DNRM Database – Regional Bores Drawing 9: DNRM Database – Bore Yields Drawing 10: Composite Piezometric Contours Drawing 11: Depth to Piezometric Surface Drawing 12: Combined Long Term Hydrograph Drawing 13: Recharge Estimate (CRD Method) Drawing 14: Regional Bore Salinity Drawing 15: MT1 Coal Seam Isopach Drawing 16: MT2 Coal Seam Isopach Drawing 17: MB2 Coal Seam Isopach Drawing 18: Hydrogeological Cross Section Drawing 19: Analytical Prediction of Mine Inflows Drawing 20: Kemmis Pit 1 Mine Pumping Against Rainfall Drawing 21: Sub Surface Reliant Groundwater Dependent Ecosystems Drawing 22: Proposed Monitoring Sites

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21.5 S

80275.00

A

1DRAWING No:

PROJECT No:

REVISION:

Aug 2013CLIENT: DATE:

LOCATION OF KEMMIS II PITKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland

BHP Mitsui Coal

Scale 1:200,000

LEGEND

Mining Lease ML4750

Proposed Pit Location

QLD DCDB

Watercourse

Railway

Roads

Place Names

Projection: Lat/Long GDA94

Kemmis II Proposed Pit

QR Farm Dam

Kemmis Pit

Mulgrave Pit

Ramp F Dam

Carborough Pit

Walker Creek

Walker Pit

Toolah Pit

Tailings Dam

Walker Creek

Carborough Creek

P9456 (P021)

140041(MB4)

Hut Bore

140050(Gas 2)

P10679

Kiss'Bore

P10680(Obs Bore 2)

P10672(Obs Bore 1)

140040(Gas 1)

640,000 645,000 650,000 655,000

7,585,000

7,590,000

7,595,000

7,600,000

7,605,000

SITE LAYOUT - SOUTH WALKER CREEK MINEKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland

CLIENT: BHP Mitsui Coal

PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

2

A

Aug 2013

0 1,000 2,000 3,000 4,000

Meters

´

Projection: AGD84 AMG Zone 55 A4 Scale 1:100,000

Monitoring Bore or Dril lhole

Surface Water Drainage

Mining Lease 4750

Proposed Pit (Kemmis II)

High : 270.351

Low : 174.743

630,000 640,000 650,000

7,580,000

7,590,000

7,600,000

7,610,000

7,620,000

REGIONAL TOPOGRAPHY & SURFACE DRAINAGE

Kemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

3

A

Aug 2013

0 2,500 5,000 7,500 10,000

Meters

´



Kemmis II Pit at 10 Years

Max ~700 m

Min ~ 150 m

Carborough R

ange

Walker Creek

Kemmis Creek

Carborough Creek

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Rainfall (mm)

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802

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150

200

250

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Rainfall & Evaporation (mm)

0510152025303540

Average Daily Temperature (oC)

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

0 2.5 5

kilometers

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CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

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CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

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CARBOROUGH CREEK

CARBOROUGH CREEK

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CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

CARBOROUGH CREEK

21.8°S

21.7°S

21.6°S

21.9°S

14

8.3

°E

14

8.4

°E

14

8.2

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21.5 S

80275.00

A

6DRAWING No:

PROJECT No:

REVISION:

Aug 2013CLIENT: DATE:

REGIONAL GEOLOGYKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland

BHP Mitsui Coal

SURFACE GEOLOGY

Quaternary Alluvium (Qa)

Tertiary to Quaternary Alluvium (TQa)

Tertiary (Td)

Tertiary Basalt Flows (Tb)

Suttor Formation (Ts)

Cretaceous Unnamed Grandiorite (Kl)

Gotthardt Granodiorite (Kgg)

Bundarra Granodiorite (Kgb)

Moolayember Formation (Rm)

Clematis Group (Re)

Rewan Formation (Rr)

Rangal Coal Measures (Pwj)

Fort Cooper Coal Measures (Pwt)

Moranbah Coal Measures (Pwb)

Exmoor Formation (Pbx)

Undivided Back Creek Group (Pb)

Scale 1:200,000

LEGEND

Watercourse

Faults

Proposed Pit Location

Projection: Lat/Long GDA94

640,000

7,590,000

7,600,000

WATER ENCOUNTERED IN COAL EXPLORATION BORESKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

7

A

Dec 2013

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013

A4

Sca

le 1

:350

,000´

GW FLOW DIRECTION

Pro

po

sed

Pit

(Ke

mm

is II

)

Infe

rre

d G

W C

on

tou

r (m

AH

D)

Inte

rpo

late

d G

W C

onto

ur (

mA

HD

)

(S

WC

Exp

lora

tion

Ho

le D

ata

Ke

mm

is E

xplo

ratio

n H

ole

RS

WL

(mA

HD

)

Pe

rmia

n G

W D

ata

ba

se B

ore

RS

WL

(mA

HD

)

Site

Ob

serv

atio

n P

oin

t R

SW

L (m

AH

D)

02,

50

05,

00

07,

50

010

,000

Me

ters

640,000 650,0007,580,000

7,590,000

7,600,000

7,610,000

DEPTH TO POTENTIOMETRIC SURFACEKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

11

A

Aug 2013

0 2,000 4,000 6,000 8,000

Meters

´Projection: AGD84 AMG Zone 55 A4 Scale 1:140,000

< 1 m

1 - 2 m

2 - 3 m

3 - 4 m

4 - 5 m

5 - 7.5 m

7.5 - 10 m

10 - 15 m

15 - 20 m

20 - 30 m

30 - 40 m

40 - 50 m

50 - 75 m

75 - 100 m

100 - 200 m

Surface Water

Proposed Pit

RE

VIS

ION

:

A

DR

AW

ING

No:

12

PR

OJE

CT

No:

802

75.0

0

OF

FIC

E:

Bris

bane

AP

PR

OV

ED

BY

: MS

DA

TE

: A

ug 2

013

DR

AW

N B

Y:B

N&

PE

D

2005

2006

2007

2008

2009

2010

2011

2012

2013

175

176

177

178

179

180

Groundwater Elevation (mAHD)

-100

0

01000

Rainfall Residual Mass Balance (mm)

RE

VIS

ION

:

A

DR

AW

ING

No:

13

PR

OJE

CT

No:

802

75.0

0

OF

FIC

E:

Bris

bane

AP

PR

OV

ED

BY

: MS

DA

TE

: A

ug 2

013

DR

AW

N B

Y: P

ED

2005

2006

2007

2008

2009

2010

2011

2012

2013

175

176

177

178

179

180

Groundwater Elevation (mAHD)

0100

200

300

400

500

Rainfall (mm)

CR

D M

etho

d (P

1068

0): %

R >

C =

0.0

5%,

Cut

-off

= 6

0 m

m,

Sy

= 0

.002

")

")")

")

")")")")

")") ")")")") ") ")")") ") ") ")

")

")

")

")

")

")")

")

") ")") ")

")

")")")")")")")")")")")")")")") ")")

")

") ")

") ") ")")")

") ") ")

")

") ")") ") ")

RE

GIO

NA

L B

OR

E S

AL

INIT

Y

Ke

mm

is I

I P

it G

rou

nd

wa

ter

Imp

ac

t As

ses

sme

nt

So

uth

Wa

lke

r C

ree

k C

oa

l M

ine

, vi

a N

eb

o,

No

rth

ern

Bo

we

n B

asi

n,

Ce

ntr

al Q

ue

en

sla

nd

CLI

EN

T:B

HP

Mits

ui C

oal

PR

OJE

CT

No:

DR

AW

ING

No:

RE

VIS

ION

:

8027

5.00

14 A

Pro

ject

ion:

AG

D84

AM

G Z

one

55

OF

FIC

E:

BN

E

DAT

E:

Aug

ust 2

013

A4

Sca

le 1

:360

,000´

Fre

sh W

ate

r (<

750

EC

in u

S/c

m)

Slig

htly

Bra

ckis

h (7

50 t

o 1

50

0)

Bra

ckis

h (

15

00 t

o 4

50

0)

Mo

der

ate

ly S

alin

e (

45

00 t

o 1

0,5

00)

Sa

line

(10

,500

to

21

,00

0)

Hig

hly

Sa

line

(2

1,0

00

to 5

2,0

00)

Brin

e (

>52

,000

)

")Q

ua

lity

Com

men

t O

nly

- P

ota

ble

")Q

ua

lity

Com

men

t O

nly

- B

rack

ish

")Q

ua

lity

Com

men

t O

nly

- S

alin

e

Pro

po

sed

Pit

(Ke

mm

is II

)

02,

50

05,

00

07,

50

010

,000

Me

ters

1

1

2

11

639,000 640,000 641,000 642,000 643,000

7,596,000

7,597,000

7,598,000

7,599,000

7,600,000

7,601,000

MT1 COAL SEAM ISOPACHKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

15

A

Aug 2013

0 250 500 750 1,000

Meters

´


A - A' Section


MT1 Isopach Contour (m)

Max 2.2 m

Min 0 m

140040

140050

A

A'

3

4

3 1

3

3

1

2

4

3

639,000 640,000 641,000 642,000 643,000

7,596,000

7,597,000

7,598,000

7,599,000

7,600,000

7,601,000

MT2 COAL SEAM ISOPACHKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

16

A

Aug 2013

0 250 500 750 1,000

Meters

´


A - A' Section


MT2 Isopach Contour (m)

Max 5.1 m

Min 0 m

A

A'

140040

140050

5

7

8

7

7

77

7

7

7

8

1

6

7

7

639,000 640,000 641,000 642,000 643,000

7,596,000

7,597,000

7,598,000

7,599,000

7,600,000

7,601,000

MB2 COAL SEAM ISOPACHKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

17

A

Aug 2013

0 250 500 750 1,000

Meters

´


A - A' Section


MB2 Isopach Contour (m)

Max 8.8 m

Min 0 m

140040

140050

A

A'

rs

260

250

240

230

220

210

200

190

180

170

160

150

140

130

120

110

100

050

045

0040

0035

0030

0025

0020

0015

0010

00

HY

DR

OG

EO

LO

GIC

AL

CR

OS

S S

EC

TIO

NK

emm

is II

Pit

Gro

undw

ater

Impa

ct A

sses

smen

tS

outh

Wal

ker

Cre

ek C

oal M

ine,

via

Neb

oN

orth

ern

Bow

en B

asin

, Cen

tral

Que

ensl

and

CLI

EN

T:B

HP

Mits

ui C

oal

PR

OJE

CT

No:

DR

AW

ING

No:

RE

VIS

ION

:

8027

5.0

0

18 A

Pro

ject

ion

: Ver

tical

Cro

ss S

ect

ion

OF

FIC

E:

BN

E

DA

TE

:A

ugus

t 20

13

A4

Sca

le a

s dr

aw

n

Elevation (mAHD)

Dis

tan

ce a

lon

g T

ran

sect

(m

)

MB

2 Co

al S

eam

QR

Far

m D

am

140040

MT

1 S

eam

Tert

iary

Sed

imen

ts

Wea

the

red

Zo

ne

(Rr)

AA

'

Pre

-dev

elo

pm

ent

Pie

zom

etri

c S

urf

ace

140050

Kem

mis

II

Pit

(Pro

pose

d a

t Yea

r 10

)

GW

Flo

w D

irec

tion

Ran

gal

Coa

lM

easu

res

Ran

gal

Coa

lM

easu

res

RE

VIS

ION

:

A

DR

AW

ING

No:

19

PR

OJE

CT

No:

802

75.0

0

OF

FIC

E:

Bris

bane

AP

PR

OV

ED

BY

: MS

DA

TE

: A

ug 2

013

DR

AW

N B

Y: P

ED

036

573

010

9514

6018

2521

90

Elaps

ed Ti

me (D

ays)

120

160

200

240

Elevation (mAHD)

0.0

0.5

1.0

1.5

2.0

2.5

Mine Inflow (L/s)

RE

VIS

ION

:

A

DR

AW

ING

No:

20

PR

OJE

CT

No:

802

75.0

0

OF

FIC

E:

Bris

bane

AP

PR

OV

ED

BY

: MS

DA

TE

: A

ug 2

013

DR

AW

N B

Y:B

N&

PE

D

Oct-1

1No

v-11

Dec-1

1Ja

n-12

Feb-1

2Ma

r-12

Apr-1

2Ma

y-12

Jun-

12Ju

l-12

Aug-

12Se

p-12

Oct-1

2No

v-12

Dec-1

2Ja

n-13

Feb-1

30246 Mine Pumping (ML/day)

01020304050

Rainfall Volume over Kemmis Pit (ML)

Kemmis II Proposed Pit

QR Farm Dam

Kemmis Pit

Mulgrave Pit

Ramp F Dam

Carborough Pit

Walker Creek

Walker Pit

Walker Creek

Carborough Creek

Kemmis Creek

P9456 (P021)

140041(MB4)

Hut Well

140050(Gas 2)

P10679

Kiss'Bore

P10672(Obs Well 1)

140040(Gas 1)

635,000 640,000 645,000 650,000

7,590,000

7,595,000

7,600,000

7,605,000

7,610,000

SUB SURFACE RELIANT GDEKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo, Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

21

A

Aug 2013

0 1,000 2,000 3,000 4,000

Meters

´


Monitoring Bore or Dril lhole


Low potential for GW interaction

Moderate potential for GW interaction

High potential for GW interaction


Mining Lease 4750

R

R

R

RRR

R

P9456 (P021)

140041(MB4)

Hut Bore

140050(Gas 2) P10679

Kiss'Bore

P10680(Obs Bore 2)

P10672(Obs Bore 1)

140040(Gas 1)

Site6

Site5

Site4

Site3

Site7

Site2

Site1

635,000 640,000 645,000 650,000 655,000 660,000

7,580,000

7,585,000

7,590,000

7,595,000

7,600,000

7,605,000

7,610,000

PROPOSED MONITORING SITESKemmis II Pit Groundwater Impact AssessmentSouth Walker Creek Coal Mine, via Nebo,Northern Bowen Basin, Central Queensland


PROJECT No:

DRAWING No:

REVISION:

DATE:

80275.00

22

A

Dec 2013

0 1,000 2,000 3,000 4,000

Meters

´


R Proposed Nested Site

R Proposed Tertiary Bore

R Proposed Shallow Permian Bore

R Proposed Permian Bore

Existing Monitoring Bore or Drillhole

Alluvium / Colluvium Extent

Mining Lease

Point Easting Northing Purpose Unit1 637398.4 7601635.0 Upgradient Background Monitoring Nested2 640900.1 7600383.2 Target Future Operations Shallow Permian3 640731.0 7597205.4 Define Hydraulic Gradient within Alluvium Tertiary4 641812.1 7596746.5 Define Hydraulic Gradient within Alluvium / Replace Kiss Bore Nested5 642255.6 7595807.9 Define Hydraulic Gradient within Alluvium Tertiary6 644094.9 7595107.5 Define Hydraulic Gradient within Alluvium Tertiary7 655106.3 7587719.1 Downgradient Tertiary Site / Value add to Network Tertiary

Documents

Report on Kemmis II Pit Groundwater Impact Assessment ... · Originally opened on a trial basis, ... existing Kemmis Pit that is located to the southeast and thought to be in the