PENRICE MINE - HYDROGEOLOGICAL INVESTIGATION

rpsaquaterra.com.au

PENRICE MINE - HYDROGEOLOGICAL INVESTIGATION


Prepared by: RPS Aquaterra Level 6 33 Franklin Street, Adelaide SA 5000 T: 61 8 8410 4000 F: 61 8 8410 6321 E: [email protected] W: rpsaquaterra.com.au Our ref: A94D/R001a Date: 6 February 2013

Prepared for: James Rowe/Mick Sanderson Penrice Soda Products Pty Ltd Solvay Road, Osborne SA 5017


A94D/R001a DOCUMENT STATUS / DISCLAIMER

Document Status

Issue Date Purpose of Document

Revision B 6 February 2013 Final Report

Revision A 25 January 2013 Draft Report for comment

Name Position Signature Date

Author James Ohanga Hydrogeologist 6 February 2013

Reviewer Subhas Nandy Senior Hydrogeologist 6 February 2013

Reviewer Hugh Middlemis Senior Principal Water Resource Engineer

6 February 2013

Disclaimer

This document is and shall remain the property of RPS Aquaterra. The document may only be used for the purposes for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised copying or use of this document in any form whatsoever is prohibited.


A94D/R001a Page i

EXECUTIVE SUMMARY

Penrice Soda Products Pty Ltd engaged RPS Aquaterra to undertake a hydrogeological assessment of the mine at Penrice Angaston, located 2.5 km north of Angaston, South Australia.

Hydrogeological investigations were required to evaluate the zone of influence and drawdown impacts for the current operation, and also the proposed deepening of the pit (to the maximum current proposed level of 243 mAHD over the next 10 years or so). Investigations included predictions of mine dewatering volumes and related effects and also investigations into the post-mining sub-regional east-west groundwater gradient and interaction with the residual pit void in terms of groundwater levels and flows.

This investigation and analytical methodology was designed to address the requirements of the mining and post-mine conditions and provide insight into the hydrological processes that influence the groundwater-related impacts. It included reviewing available data on groundwater levels within a 5 km radius of the mine and analyses of groundwater dynamics against climatic and pumping influences.

The key findings of the investigations were:

Hydrogeological assessment of groundwater level trends using Cumulative Rainfall Deviation (CRD) curves revealed that the groundwater trends are mainly influenced by rainfall recharge and subsequent natural recession.

The groundwater level hydrographs showed no sign of continuous recession and groundwater levels recovered during periods of high rainfall. This is consistent with the Department for Water, Environment and Natural Resources (DEWNR) groundwater and salinity status report (2011), which indicated that there is low risk to beneficial use of groundwater resource due to any known activities (including mining) in the region for at least 15 years.

There appears to be a zone very close to the northern end of the mine pit (within 1 km) which showed minor groundwater recession possibly from mine dewatering as indicated by trends in observation bore MOR 126 and discussed in section 4.

In-pit evaporation from the Penrice mine climate station was benchmarked against the Nuriootpa BoM data, indicating that in-pit Penrice mine evaporation is 15% higher than evaporation at the Nuriootpa station.

Long term groundwater recovery post mining will be slow, relying on inflow from the fractured rock aquifer and from rainfall, balanced against evaporation from the pit lake. The analytical groundwater model (using the evaporation data from the in-pit climate station, benchmarked against long term Nuriootpa BoM data) indicates that the final pit will fill to approximately 80% of the predicted long term equilibrium level within about 40 years post-mining, and then it will take well over 150 years for post mining groundwater levels to establish the equilibrium level somewhere between 275 and 285 mAHD. It is predicted that when the pit lake reaches equilibrium (post-mining), the final pit lake level will be approximately the level at which groundwater throughflow should occur, which would reduce the potential for major salinity impacts.

Long term post mining hydrogeological impacts (in terms of groundwater levels and availability) are thus predicted to be similar to the current impacts because the final pit lake water level is predicted to eventually recover to about the current pit water level (279 mAHD).

Further analysis is required to confirm this finding, to test sensitivity to assumptions of evaporation and other parameters, and to quantify any related salinity impacts. This should be undertaken with a numerical groundwater model.


A94D/R001a Page iii

TABLE OF CONTENTS

1. INTRODUCTION ...................................................................................................................... 1 1.1 Background ............................................................................................................................................ 1

1.2 Scope of Work ........................................................................................................................................ 2

2. REGIONAL SETTING .............................................................................................................. 4 2.1 Topography ............................................................................................................................................ 4

2.2 Climate ................................................................................................................................................... 4

2.3 Land Use ................................................................................................................................................ 4

2.4 Hydrogeology ......................................................................................................................................... 4

3. DATA ACQUISITION ............................................................................................................... 7 3.1 Rainfall .................................................................................................................................................... 7

3.2 Groundwater ........................................................................................................................................... 7

3.3 Groundwater Allocation .......................................................................................................................... 8

3.4 Groundwater Salinity .............................................................................................................................. 9

4. REVIEW AND DATA ANALYSIS .......................................................................................... 10 4.1 Cumulative rainfall deviation analysis ................................................................................................... 10

4.2 Drawdown assessment ......................................................................................................................... 12

4.3 In-pit evaporation assessment .............................................................................................................. 14

5. POTENTIAL IMPACT OF MINING VOID .............................................................................. 15 5.1 Operational dewatering ......................................................................................................................... 15

5.1.1 Types of mine voids ................................................................................................................ 15

5.1.2 Estimated mine inflows ........................................................................................................... 16

5.1.3 Long term pit void ................................................................................................................... 17

6. CONCLUSIONS AND RECOMMENDATIONS ..................................................................... 21 6.1 Mine Operational Stage: ....................................................................................................................... 21

6.2 Post-Mining Void .................................................................................................................................. 21

6.3 Recommendation ................................................................................................................................. 21

6.3.1 Numerical Modelling ............................................................................................................... 21

6.3.2 Salinity of the pit lake .............................................................................................................. 21

7. REFERENCES ....................................................................................................................... 22

TABLES

Table 2.1: Hydrogeology of Barossa Prescribed Water Resource Area (PWA) .................................................. 5 Table 3.1: Observation bores data ...................................................................................................................... 7 Table 4.1: CRD analysis for the fractured rock aquifer ..................................................................................... 10 Table 4.2: CRD analysis for Barossa Valley Sedimentary Aquifer .................................................................... 11 Table 4.3: Nuriootpa Evaporation for 2011 ....................................................................................................... 14


Page iv A94D/R001a

FIGURES

Figure 1: Current Mine Plan Figure 2: Regional Climate Figure 3: Schematic Cross Section of the Barossa Basin in the vicinity of the Penrice Mine Figure 4: Spatial Representation of Analysed Bores Figure 5: Pit floor evaporation vs. mine elevation Figure 6: Hydrogeological Environments for Mine Voids Figure 7: Pit Inflows Calculations Figure 8: Long Term Predicted Post Mining Water Level Figure 9: Penrice Groundwater Model

APPENDICES

Appendix A: CRD Hydrographs Appendix B: Penrice in-pit evaporation analysis Appendix C: Water allocation data


A94D/R001a Page 1

1. INTRODUCTION

Penrice Soda Products Pty Ltd (Penrice) seeks to optimise its operation in their mine at Angaston and engaged RPS Aquaterra to undertake hydrogeological investigations. The studies are designed to evaluate the zone of influence and drawdown impacts due to the current mine operation on local aquifers and potentially affected groundwater users, and also to investigate the possible impacts of the proposed deepening of the pit (to the maximum current proposed level of 243mAHD over the next 10 years).

1.1 Background

RPS Aquaterra understand that the mine has an anticipated remaining mine life of approximately 25 years, the Department for Manufacturing, Innovation, Trade, Resources and Energy (DMITRE) (in collaboration with the Department of Environment, Water, and Natural Resources (DEWNR)) require a predictive assessment of the potential impacts on the hydrogeological system at the mine and surrounds during mining and post mine closure, including proposed long-term management options for the post-mining void.

The mine produces high- and low-grade limestone. The high-grade limestone is used in the production of soda ash (for use in glass making), and the low-grade limestone has various uses including concrete manufacture, aggregate, foundry flux, etc. The mine has been operating for approximately 60 years; with an anticipated future mine life of high-grade limestone reserves of 25 years. These estimations are based on the 2012 Resource and Reserve statements that were released after the exploration drilling programme completed in January 2012.

The mine itself is located on the eastern margin of the Barossa Basin, within the fractured rock metasediments that form the Barossa Ranges, though the mine does not intersect either the Upper or Lower Tertiary aquifers of the Barossa Basin. The pre-mine depth to groundwater (within the fractured rock aquifer) varied between approximately 20-30 m below ground level (bgl) (reported as 348 m AHD, Golder, 2008), with variation in depth to water related to the topography of the mine being located on the top of a hill. Groundwater flow within the fractured rock aquifer is interpreted to be from east to west but may flow radially into the mine as a result of topography (Golder, 2008). Groundwater salinity within the fractured rock aquifer varies from 500 to 3,000 mg/L and is highly variable across the Barossa Basin (AMLNRMB, 2006).

As mining at the site has progressed to a depth of about 267 mAHD, about 83 m below the depth of the pre-mining water table, ongoing dewatering of groundwater inflows from the walls and base of the pit is required. Groundwater and surface water run-off is collected and stored in a temporary pit lake (periodically moved based on operational requirements), which is currently located at the northern end of the pit (dimensions about 200x100m). The water is used by Penrice for dust suppression and product preparation.

Schist overburden is removed and stored in a mine waste dump adjacent to the pit. Additional land, adjacent the mine to the west, was purchased by Penrice in 2008 to enable expansion of the waste dump, which will subsequently enable deepening of the pit. A Miscellaneous Purpose License (MPL) is required for the storage of overburden on this land while the expansion program required the submission of a Mine and Rehabilitation Plan (MARP) for which was submitted by Penrice as in Interim MARP in December 2008 (Penrice, 2008).

The mine itself has a long and narrow surface footprint, is oriented in a north-northeast/south-southwest direction with the current pit floor at about 267 mAHD, or approximately 83 m below the pre-mining groundwater level. The pre-mining groundwater was intersected approximately 30 m below ground level (bgl), an equivalent elevation of 350 mAHD. A possible future mine plan could see the final elevation of the pit floor at 196 mAHD (Figure 1), although the current approval is approximately 140 m depth (243 mAHD).

Penrice have indicated that the mine currently has two licences for groundwater extraction of 102.2 ML/year (Licence No. 3778), and 28.16 ML/year (Licence 3724) for use in dust suppression and processing of the limestone ore, taking the total licence for water extraction to 130.36 ML/year.


Page 2 A94D/R001a

It is understood that a number of geological and hydrogeological assessments have been undertaken on the operating aspects of the mine, with Golder (2008) the most relevant mine-specific report referenced during the current assessment. Several government reports on the hydrogeology of the Barossa region have also been considered in preparing in this report.

1.2 Scope of Work

Analyse data on rainfall & evaporation, groundwater levels and extraction, and use data from the Penrice in-pit climate station on evaporation (established in 2010 for use in collecting weather data for hydrogeological assessments of the long term post-closure management options).

Establish causal/analytical relationships between groundwater levels and rainfall using cumulative residual deviation methods.

Investigate whether there is an effect on causal relationships and/or local/regional groundwater levels due to Penrice extraction.

Predict mine dewatering volumes and related effect due to proposed deepening of the pit,

Investigate the post-mining sub-regional east-west groundwater gradient and interaction with the residual long term pit void (pit lake) in terms of groundwater levels and flows.

Elevation 196mAHD - Area 52096m2









DATA SOURCES

APPROX SCALE

Input data sources here

@ A4

Disclaimer: While all reasonable care has been taken to ensure the informationcontained on this map is up to date and accurate, no guarantee is given that theinformation portrayed is free from error or omission. Please verify the accuracyof all information prior to use.

GDA 1994 MGA Zone 54

FIGURE 1Penrice

Mine Pit Elevations!

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!CEDUNA

WHYALLA

ADELAIDE

ROXBY DOWNS

PORT LINCOLN

PORT AUGUSTA

LEGENDPit Elevation 196mAHDPit Elevation 220mAHDPit Elevation 232mAHDPit Elevation 244mAHDPit Elevation 256mAHDPit Elevation 268mAHDPit Elevation 281mAHDPit Elevation 304mAHDPit Elevation 316mAHD

±

1:5,000

A225_001 Rev: A Produced: Loader Reviewed: Loader Date: 26/03/2012

50 0 50 100

Metres

!


Page 4 A94D/R001a

2. REGIONAL SETTING

2.1 Topography

The Penrice mine is situated in the foothills that define the eastern extent of the of the Barossa basin, in undulating topography. The topography near the mine varies from 310 mAHD in the Barossa valley to 390 mAHD on the hills to the east of Penrice.

2.2 Climate

The regional climate is classified as Mediterranean with cold wet winters and hot dry summers. The long term regional climatic summary for Nuriootpa Bureau of Meteorology (BOM) weather station 23373 located about 5km west of the Penrice mine has been used to represent the regional climate as it is the only station in the region that measures evaporation. According to the weather statistics, most rain in the region falls between April and October and the mean daily evaporation is higher in the hotter months compared to the cooler months. The area around Penrice and Barossa ranges experiences higher mean monthly rainfall in cooler months according to data obtained from Angaston BOM station located 2.5 km south of Penrice (Figure 2).

Figure 2: Regional Climate

2.3 Land Use

The dominant land uses within the region are vineyards, cropping, stock grazing, and rural living. This catchment contains proclaimed water resources, which are regulated to prevent overexploitation and were proclaimed in 1989. In 1992 this area was expanded to cover groundwater and watercourses in the Lyndoch and Flaxman Valleys, Jacobs Creek and Tanunda Creek (DLWBC, 2003).

2.4 Hydrogeology

A conceptual hydrogeological model for the area has been presented in numerous previous documents and can be summarised as follows:

Groundwater within the Barossa Basin has been broadly grouped into three principal aquifer systems: an Upper Aquifer found in alluvium and representing the water table aquifer within the extent of the basin; a Lower Aquifer comprised of Tertiary Aged sediments; and a fractured rock aquifer contained within Pre-Cambrian and Paleozoic metasediments (shales through to crystalline marbles). The metasediments surround and underlie the younger sediments of the Basin (Table 2.1 & Figure 3).


A94D/R001a Page 5

The three aquifer systems are hydraulically connected, with the primary source of groundwater recharge to the Basin being from rainfall falling on the foothills (Barossa Ranges) that delineate the eastern boundary of the Barossa Basin and recharging the fractured rock aquifer. Groundwater flows in a generally westerly direction, with recharge to the sedimentary aquifers primarily occurring through lateral flow from the fractured rock aquifer.

Table 2.1: Hydrogeology of Barossa Prescribed Water Resource Area (PWA)

AGE STRATIGRAPHY HYDROGEOLOGY

Unit Lithology Unit Description

Qu

ater

nar

y

Hol

ocen

e

Undifferentiated Quaternary

Sands, gravels and silts of modern drainage channels

Upper aquifer

Unconfined/confined aquifer, salinities from 900 to 12 000 mg/L, used for irrigation and stock supplies

Ple

isto

cene

Pooraka Formation

Red-brown sandy clays with minor gravel lenses near ranges

Confining layer

Ter

tiar

y

Mio

cene

(ea

rly-

late

)

Rowland Flat Sand

Non-carbonaceous clays, gravels, sands and silts

Aquitard Confined aquifer, salinities 400 – 3000 mg/L, used extensively for irrigation

Mio

cene

(e

arly

)

Rowland Flat Sand

Carbonaceous (lignitic) clays, brown

Lower aquifer

Confined/unconfined aquifer, supplies generally low, salinities highly variable – from 450 to 3500 mg/L

Olig

ocen

e (e

arly

)

Carbonaceous clays, gravel, sands and silt

Cam

bri

an Kanmantoo/

Normanville Groups

Metamorphosed greywacke, schist, marble

Fractured rock aquifer

Confined/ unconfined aquifer, supplies generally low, salinities highly variable – from 450 to 3500 mg/L

Pro

tero

zoic

Adelaide System

Siltstones, shales, sandstones, quartzites


Page 6 A94D/R001a

Figure 3: Schematic Cross Section of the Barossa Basin in the vicinity of the Penrice Mine

Figure Source: Brown (DWLBC), 2002.

Note that the Figure 3 orientation is section C – west to C’ – east; the Penrice Mine is located within the Fractured Rock to the east of the sediments of the Barossa Basin, i.e. to the east of the extent of both the Upper and Lower Tertiary aquifers.


A94D/R001a Page 7

3. DATA ACQUISITION

The data used to undertake this investigation was acquired from the following sources:

Meteorological data from the Bureau of Meteorology (BoM) and Penrice in-pit climate station,

Groundwater levels from bores within 5 km of the mine (from DEWNR website), and

Volumetric flow measurements from DEWNR (for irrigation bores) and Penrice mine.

3.1 Rainfall

Rainfall data used in this investigation was obtained from BoM climate data online provides accessible online (accessible through http://www.bom.gov.au/climate/data/ ). There are a number of stations around the Penrice area including Angaston, Angaston Creek (Saltram Gully), Penrice Alert, Barossa Valley (Duckponds Creek), Nuriootpa Viticultural and Nuriootpa Alert.

The most ideal station for rainfall data was the Angaston BOM weather station 023300 because of its proximity to Penrice mine (about 2.5 km south) and also the station holds long term historical rainfall data.

3.2 Groundwater

Groundwater data within 5 km radius of the mine site in the Barossa Lyndoch Valley Obswell network was used in this investigation (accessible through DEWNR Online Data Application www.WaterConnect.sa.gov.au/GD/ ). There were 1060 bores identified within the selected radius both in the fractured rock aquifer and the Barossa Valley Sedimentary Aquifer (Tertiary and Quaternary) but only a few bores had data that was suitable for analysis.

Although the aim was to collect and analyse groundwater mainly within the fractured rock zone, similar data was considered in the Barossa Valley sedimentary aquifer and also from bore data available for unspecified aquifer units located close to the mine pit (<500 m). Summary information for observation bores identified and found to have suitable for analysis are shown in Table 3.1.

Table 3.1: Observation bores data

Observation bore.

Drillhole Name

Drill Depth (mbgl)

RSWL (mAHD)

SWL (mbgl)

pH EC (µS/cm)

Yield (L/s)

FRACTURED ROCK AQUIFER

MOR124 PENRICE QUARRY

9.1 369.03 1.32 8.35 1670


5.45 357.57 0.96 1.8 2700 0.06


23 332.32 14.42 6.7 2110 1.64

MOR127 BRIAN KELLETT- PENRICE QUARRY

85.34 349.43 19.77 7.5 1974 15.15


7.24 366.99 1.1 6.6 2180 NA

MOR130 MESA - PENRICE QUARRY

2.7 364.87 0.83 7.5 2100 NA


39.93 315.43 11.59 7.8 520 0.19


28.04 351.39 6.14 7 2170 1.89

MOR256 MESA OBS 74.5 287.39 33.4 7.1 2510 2.3

MOR263 - 43.6 333.64 14.71 7.09 1980 0.5


Page 8 A94D/R001a

Observation bore.

Drillhole Name

Drill Depth (mbgl)

RSWL (mAHD)

SWL (mbgl)

pH EC (µS/cm)

Yield (L/s)

BAROSSA VALLEY SEDIMENTARY AQUIFER

MOR026 PENRICE QUARRY WELL 55.96 271.86 38.71 7.4 1160 1.9

MOR032 PRIVATE - 4080 GROPE 33.83 270.95 10.07 6.7 2730 4.42

MOR039 20.73 270.5 8.71 7.5 2340 3.16

MOR049 SPANAGEL 3730 20.73 273.07 10.54 7.1 3810 NA

MOR072 MESA 46.3 270.46 19.98 6.9 3440 NA

MOR074 TCWQ 114 24 270.56 18.42 6.7 8330 NA

MOR102 MESA- PENRICE QUARRY 58 271.65 27.24 7.5 3250

NA

MOR103 MESA- PENRICE QUARRY 58 271.38 27.51 7 2730

NA

MOR199 MESA OBS 100.5 271.22 8.35 7.3 2770 3

MOR200 MESA OBS 57 271.13 8.49 7.6 1841 1.5

UNSPECIFIED AQUIFER

MOR123 PENRICE QUARRY -PRIVATE

51.82 25.32 291.15 7.4 2010 NA

MOR122 PENRICE QUARRY-BURGMER / SLEEP 3664

NA 292.53 23.07 7.5 1945 1.01

MOR264 BURGMEISTER 3715/3738

NA 287.91 36.67 NA 1538 NA

MOR282 NA 72 57.51 270.2 960 0.15

NA = Not Available.

SWL = Standing Water Level.

RSWL = Reduced SWL.

mbgl = metres below ground level.

3.3 Groundwater Allocation

Within the Barossa Prescribed Water Resources Area, groundwater is extracted from Tertiary sediments (Upper and Lower aquifers) within the Barossa Valley, as well as from the fractured rock aquifer that underlies and surrounds the valley. Metered extractions totalled 2103 ML for 2009–10, well below the current allocation of 7400 ML, with 54% being supplied from the fractured rock aquifer, 33% from the Lower Aquifer and 13% from the Upper Aquifer (DEWNR, 2011). The main groundwater uses in the study area includes irrigation, stock, industrial recreation and domestic.

Licensed bores with sufficient groundwater allocation data were considered in the analysis to investigate whether declining groundwater level trends could be attributed to groundwater use based on the allocations, or to the mine dewatering. Licensed bores which had groundwater allocation data that were used in the analysis are shown in Appendix C.


A94D/R001a Page 9

3.4 Groundwater Salinity

Table 3.1 shows that the bores in the fractured rock aquifer exhibit salinity mostly above 2000 µs/cm (1300 mg/L), while the down-gradient sedimentary aquifer shows generally higher salinity above 2500 µS/cm (1600 mg/L). There are three notable exceptions that have lower salinity, with two sedimentary bores in the range 1100 to 1900 µS/cm (700 to 1200 mg/L), and one fractured rock bore at 520 µS/cm (340 mg/L). Therefore the groundwater in the area can be characterised as generally sub-potable or brackish, and marginally suitable for vine irrigation considering a nominal water salinity value of 1500 mg/L for vines.


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4. REVIEW AND DATA ANALYSIS

Groundwater monitoring data were analysed and assessed in this section in order to separate regional groundwater recession from potential mine dewatering effects, and from third party extraction effects where possible. Time series groundwater level data trends around the pit were compared to those from the wider Barossa Valley (with interpretations available from DEWNR reports, including the recent Barossa Status Report) and confirmed that the Penrice mine dewatering influence does not extend more than about 1km from the pit. The focus was on the fractured rock aquifer system (as suggested by DMITRE), but data from the Barossa Valley sedimentary aquifer system were also considered.

The Cumulative Rainfall Deviation (CRD) curves were used to relate to changes in groundwater levels to rainfall effects. This approach has recently been used by RPS Aquaterra to estimate recharge from the Mt Lofty Ranges fractured rock aquifer in a project to develop a numerical model of the Adelaide Plains aquifer system for the DEWNR.

4.1 Cumulative rainfall deviation analysis

Cumulative rainfall deviation curve (CRD) analysis as an investigative methodology is often used to evaluate temporal correlation of rainfall with groundwater levels. In this analysis groundwater level data is used to define the period of high and low groundwater level independent of rainfall. Analysis of the relationship between time series of rainfall and water level is used determine whether changes in water level could be explained by the changes in rainfall or otherwise, and if so gain some understanding of the processes involved.

The CRD represents the cumulative sum of rainfall deviations from the long term average and defines above and below average rainfall periods in the long term recorded.

CRD is derived using the formula:

Where:

is the time step or time interval - a monthly time step was used in this case

is the ith element of the series representing the average value over the time interval ∆t (mm/month); and

is the long term average (mean), expressed in the same unit as .

The hydrographs produced in this analysis are attached in Appendix A and a description of the relationships is summarised in Table 4.1 for the fractured rock aquifer and in Table 4.2 for the Barossa Valley Sedimentary Aquifer.

Table 4.1: CRD analysis for the fractured rock aquifer

Observation bore

Monitoring Period

Description

MOR126 1974 – 2012 - Groundwater level display correlation with CRD curve.

- Water level recession post 1998 (drought) but a period of high rainfall in 2005 led to its recovery. Possible minor effects due to Penrice mine.

MOR129 1974 - 2005 - Groundwater level display correlation with CRD curve.

- More random water level fluctuations post 1992

MOR125

1978 - 1986 - Groundwater level generally receding though not significantly (less than 1m);

- Groundwater level displays some correlation with CRD curve and seemed to rise towards the end of monitoring period.

MOR127 1969 – 1980 - Groundwater level display correlation with CRD curve.



A94D/R001a Page 11

Observation bore

Monitoring Period

Description


MOR263 1996 - 2012 - Groundwater level display good correlation with CRD curve.

MOR256 1996 - 2009 - Random fluctuations in groundwater levels could not be attributed definitively to rainfall events (possible local pumping?).



Table 4.2: CRD analysis for Barossa Valley Sedimentary Aquifer

Observation bore

Monitoring Period

Description

MOR026 1961 - 1987 - Groundwater level is varied and does not clearly correlate to CRD curve (possible local pumping effects?).

- Initial water levels were recorded around 300 mAHD but there was a sudden recession by about 25m in the period 1965 - 1966 (possible deepening of the bore).

MOR032 1962 – 2012 - Groundwater level displays some correlation with CRD curve.

MOR039 1961 - 1987 - Groundwater level displays some correlation with CRD curve.

- Periods of random groundwater level fluctuations observed

MOR049 1961 – 1987 - Groundwater level displays some correlation with CRD curve.

- Periods of random groundwater level fluctuations observed



- Water level recession post 1998 (drought and/or irrigation extraction)




MOR200 1988 - 2012 - Groundwater level displays some correlation with CRD curve.

- Periods of random groundwater level fluctuations observed.

Table 4.3: CRD analysis for Unspecified Aquifer

Observation bore

Monitoring Period

Description

MOR123

1972 - 1999 - Fluctuation of water level is high (>10 m). Possible pumping impact (perhaps from the mine?) up until 1992. Groundwater level then showed good correlation with rainfall from 1992 to 1998, suggesting that the previous influence was other pumping, not the mine.

MOR122 1978-1986 - Fluctuation of water level is high (>10 m). Possible pumping impact from the mine.

MOR264 1996-2012 - Fluctuation of water level is high (>10 m). Possible pumping impact from the mine.

MOR282 2004-2012 - Fluctuation of water level is high (~10 m). Water level correlates with rainfall from 2004 to 2009 and then some influence of recharge was noted.


Page 12 A94D/R001a

4.2 Drawdown assessment

The CRD analysis is represented spatially in Figure 4 and included selected hydrographs from the Fractured Rock and Barossa Sediments and water allocations bar graph to create an overall picture of the regional groundwater dynamics. All other hydrographs are presented in Appendix A.

The CRD curves were analysed to establish whether groundwater dewatering activity by Penrice is impacting on regional groundwater level trends. The analyses have not shown any material trends attributable to the Penrice mine, but rather it is clear that groundwater levels are mainly influenced by rainfall climatic conditions notably rainfall recharge.

While this assessment seems to suggest that there are no adverse groundwater level trends in the study area, groundwater recession is evident in specific locations such as in MOR074 in the sedimentary aquifer and MOR126 in the fractured rock aquifer (Figure 4). Such recession can equally be attributed to any of the competing groundwater uses such as irrigation, stock and mining because the groundwater level hydrographs seems to be consistent throughout the study area.

Despite this there is some evidence of recession in groundwater levels in the fractured rock zone close to the mine (within 1km) around the northern end of the pit as evidenced in the pattern of MOR126 however it is not possible to determine if this is attributable to mine dewatering. But the influence does not extend very far regionally (e.g. there is no apparent influence on bores near the southern end of the pit). Observation bores (MOR122, MOR123, and MOR264) which are installed within an unspecified aquifer and located within 500 m of the north pit boundary are showing some effects that are interpreted as due to mine extraction, although there are also some correlations with rainfall (CRD) data.

There is some evidence to suggest that groundwater use for irrigation in the Barossa Sediments can cause groundwater recessions; as demonstrated by the trend of bore MOR074 which is located close to a bore with the largest groundwater allocation in the area of study.

This assessment is in agreement with the 2011 Barossa PWRA Groundwater Status Report (DEWNR, 2011) which has reported that groundwater levels in the fractured rock aquifer in the region display relationship consistent with rainfall patterns. The report also indicated a stable salinity trends for observation bores (MOR164 and MOR156) in fractured rock aquifer located close to the mine.

In overall terms, there is evidence of pumping causing drawdown in proximity to large irrigation allocations, and also within 500 metres of the mine (perhaps up to 1000 metres). However, major rainfall events seem to substantially replenish the aquifer, and we concur with DEWNR view that there are no concerns about long term trends in groundwater levels.

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!

!

!

!

!

!

!!

!!!

!!

!

!(

!(

NURIOOTPA

PENRICE

ANGASTON

TANUNDA

MOR131

MOR263

MOR124

MOR125

MOR126

MOR129MOR130

MOR132

MOR256

9300

40500

6800

44342

205910

3600

23500

1100014500

11700

13400

16830

26100

18224

10000

4100

3080

8100

10900

182256100

41720

249000

16830

11000

163387

16830

87211

55330

3250

4730

43000

4000

11300

28160

69500

8000

102200

20200

511004900

7100

16200

35400

15500

12200

127300

37300

6800

30500

19100

23300

23600

MOR026

MOR032

MOR039

MOR049

MOR072

MOR074

MOR102MOR103

MOR199

MOR200MOR122

MOR123MOR264

MOR282

MOR164

MOR165

311000

311000

313000

313000

315000

315000

317000

317000

319000

319000

321000

321000

323000

323000

6178

000

6178

000

6180

000

6180

000

6182

000

6182

000

6184

000

6184

000

6186

000

6186

000

!!

!

!

!

!

HORSHAM

RENMARK MILDURA

ADELAIDE

±

FIGURE 4PENRICE QUARRYHydrogeological Investigation

LEGENDAllocation in the Fractured Rock Aquifer

120,000

Allocation in Fractured Rock (KL/yr)

Allocation in sedimentary aquifer

64,000

AllocationAQUIFERS

Sedimentary AquiferFractured Rock Aquifer

! Observation Bores in Sedimentary Basin

!( Observation Bores in Fractured Rock

! Observation Bores in Unspecified Aquifer

"/ Localityroads

DATA SOURCES

APPROX SCALE

Bureau of MeteorologyDepartment for Water

@ A3

Disclaimer: While all reasonable care has been taken to ensure the information contained onthis map is up to date and accurate, no guarantee is given that the information portrayed isfree from error or omission. Please verify the accuracy of all information prior to use.

1:40,000

GDA 1994 MGA Zone 54

A225_001 Rev: A Produced: Loader Reviewed: Loader Date: 26/03/2012

500 0 500 1,000

Metres

Fractured Rock AquiferAllocations (kL/year)

-400

-200

0

200

400

600

800

1,000

269

274

279

284

289

294

299

304

309

1950 1960 1970 1980 1990 2000 2010

CRD (

mm)

Water

Leve

l (m)

Year

MOR026Reduced Water LevelCRD

-400

-200

0

200

400

600

800

1,000

270

271

272

273

274

275

276

277

278

279

280

1950 1960 1970 1980 1990 2000 2010

CRD (

mm)

Water

Leve

l (m)

Year


-400

-200

0

200

400

600

800

1,000

268

269

270

271

272

273

274

275

276

277

278

1950 1960 1970 1980 1990 2000 2010

CRD (

mm)

Water

Level

(m)

Year


-400

-200

0

200

400

600

800

1,000

268

269

270

271

272

273

274

275

276

277

278

1950 1960 1970 1980 1990 2000 2010

CRD (

mm)

Water

Level

(m)

Year


-400

-200

0

200

400

600

800

1,000

270

271

272

273

274

275

276

277

278

279

280

1950 1960 1970 1980 1990 2000 2010

Water

Leve

l (m)

Year


-400

-200

0

200

400

600

800

363

364

365

366

367

368

369

370

371

372

373

1968

1970

1972

1974

1976

1978

1981

1983

1985

1987

1989

1992

1994

1996

1998

2000

2003

2005

2007

2009

2011

Cumu

lative

Rainf

all De

viatio

n (mm

)

Redu

ced W

ater L

evel (m

AHD)

Year


-400

-200

0

200

400

600

800

330

332

334

336

338

340

342

344

346

348

350

1968

1970

1972

1974

1976

1978

1981

1983

1985

1987

1989

1992

1994

1996

1998

2000

2003

2005

2007

2009

2011

Cumu

lative

Rainf

all De

viatio

n (mm

)

Redu

ced W

ater L

evel (m

AHD)

Year


-400.00

-200.00

0.00

200.00

400.00

600.00

800.00

313

314

315

316

317

318

319

320

321

322

323

1968

1970

1972

1974

1976

1978

1981

1983

1985

1987

1989

1992

1994

1996

1998

2000

2003

2005

2007

2009

2011

Cumu

lative

Rainf

all De

viatio

n (mm

)

Redu

ced W

ater L

evel (m

AHD)

Year


-400

-200

0

200

400

600

800

362

363

364

365

366

367

368

369

370

371

372

1968

1970

1972

1974

1976

1978

1981

1983

1985

1987

1989

1992

1994

1996

1998

2000

2003

2005

2007

2009

2011

Cumu

lative

Rainf

all De

viatio

n (mm

)

Redu

ced W

ater L

evel (m

AHD)

Year


-400

-200

0

200

400

600

800

280

281

282

283

284

285

286

287

288

289

290

1968

1970

1972

1974

1976

1978

1981

1983

1985

1987

1989

1992

1994

1996

1998

2000

2003

2005

2007

2009

2011

Cumu

lative

Rainf

all De

viatio

n (mm

)

Redu

ced W

ater L

evel (m

AHD)

Year


Sedimentary Aquifer Fractured Rock Aquifer

Barossa Sediments AquiferAllocations (kL/year)


Page 14 A94D/R001a

4.3 In-pit evaporation assessment

Assessment of post closure mining water balance requires examination of in-pit evaporation in order to conduct a meaningful water balance assessment. Penrice quarry has been operating an in pit weather station since March 2011. Recent evaporation analysis conducted to benchmark in-pit evaporation data against the Nuriootpa BoM station (the only station with evaporation data in the region) found that in-pit evaporation is slightly higher than Nuriootpa evaporation by a factor of 1.15. The finding from this assessment is attached in Appendix B.

The annual evaporation for Nuriootpa BoM station in 2011 (the year when the in-pit weather station was running) was 1,587 mm per annum (Table 4.3). Applying the in-pit evaporation factor to Nuriootpa, the current annual in-pit evaporation could be established at 1,825 mm per year.

Table 4.3: Nuriootpa Evaporation for 2011

Total Monthly Evaporation 2011 (mm) Nuriootpa BOM station

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

262.4 200.3 129.8 103.6 63.6 52.6 45.6 63.4 116.4 125.2 196.7 227.8 1587

Evaporation and elevation relationship for the potential post-mine pit lake was established based on the current mine plan surface areas and the actual evaporation in the mine pit which was established at about 1825 mm/year. The curve shows that evaporation will increase as the mine pit void water level increases. This relationship has been used to predict the final pit lake equilibrium in the mine prediction model, because as the pit surface area increases, evaporation will increase and is expected to exceed the amount of groundwater inflow at some point (Figure 5).

Figure 5: Pit floor evaporation vs. mine elevation


A94D/R001a Page 15

5. POTENTIAL IMPACT OF MINING VOID

The post-mining analytical (water balance) model developed by Aquaterra (2009) was updated and then used to predict the influence of inflow (recharge) from the Mt Lofty Ranges fractured rock aquifer on the final pit void lake character. This tool is suitable for exploration of mine closure options, but this scope of work will only consider the “no intervention” case (i.e. no backfill).

5.1 Operational dewatering

Mining at the site has progressed about 83 m below the pre-mining depth to water table, as such ongoing dewatering of groundwater inflows from the walls and base of the pit is required. Groundwater and surface water run-off is collected and stored in a temporary pit lake (periodically moved based on operational requirements), which is currently located at the northern end of the pit (dimensions about 200 x 100 m). The water is used by Penrice for dust suppression and product preparation (Golder, 2008). Abstraction of this water occurs under an existing licence for use of 102.2 ML/yr, (Licence No. 3778) and 28.16 ML/year (Licence No 3724). It is estimated 130 ML/year of water is pumped out of the mine pit under the current mine dewatering regime.

In 2008 Golder undertook an assessment of potential impacts on the groundwater table from operational dewatering. Their assessment predicted a likely cone of depression of up to 650 m radius from the mine as a result of mine dewatering. During the assessment Golder also undertook a review of hydrographs for seven observation bores located within the predicted cone of depression. With the exception of one bore, the hydrographs did not show any trends to indicate a decrease in groundwater levels during the time that any significant dewatering has been undertaken at the mine (within the last 20-30 years). One observation well located approximately 200 m to the north-east of the pit displayed an overall decrease in water level since the early 1990’s, and hence may be affected by mine dewatering, however two periods of 1-3 yrs of significant water level rise (>5 m) during this time are inconsistent with the overall trend and may be reflective of other influences on the water table (e.g. increased recharge, changes in irrigation abstraction from local irrigation bores, etc.). The outcome in this investigation as described in section 4 seems to be consistent with the 2008 Golder assessment, Post mining impacts.

5.1.1 Types of mine voids

On cessation of mining it is understood that, based on the low volume of waste compared to mined limestone ‘ore’, compounded by high potential costs associated with backfilling a void of narrow width with high pit walls, that there is no indication that the final mine void will be backfilled.

Groundwater levels will begin to recover (rebound) on completion of dewatering activities at the mine, and the water table will begin to rise towards the pre-mining level (about 350 m AHD), gradually filling the residual void to form a lake in the base of the open pit void. The final water level of the pit lake will be determined by the eventual balance between inflows and evaporation. Initially, inflows will be high, because the hydraulic gradient driving inflows from the aquifer would be at a maximum due to the water level being at base of the pit. As the water level in the pit rises, inflows decrease due to decreased hydraulic gradients. As the open water area of the pit lake increases so to would evaporation from it. Eventually, equilibrium is reached between the inflows and evaporation. The extent to which the water level will recover and the impact of this on the groundwater system will be largely driven by the local hydrogeology, with the potential for three broad hydrogeological environments developing, as described by Johnson and Wright, (2003) (after Commander et al., (1994)):

Groundwater sink – a groundwater sink is created within a mine void when the evaporation rate exceeds the rate of groundwater inflow. Under these conditions the water level will recover to a level lower than the original pre-mining standing water level. Salinity within the resultant pit lake will increase overtime due to no outflow from the void and continued evaporation. This is the most likely scenario for a fractured rock aquifer system within a hard-rock mine (see Case 1, Figure 6).


Page 16 A94D/R001a

Groundwater throughflow – when groundwater inflow exceeds evaporation, the void will act as a throughflow cell. Water level recovery is likely to be slow and stabilise below the pre-mining standing water level. Salinity within the pit lake will increase over time, and result in increased groundwater salinities down gradient of the pit as groundwater flows across the wall of the pit and back into the aquifer. Increases in groundwater salinity and the extent of down-gradient impact will be largely dependent upon the rate of groundwater flow through the pit. Groundwater throughflow is most likely to occur in voids in high-permeability ore-bodies surrounded by low permeability rocks (see Case 2, Figure 6).

Groundwater recharge – occurs when inflow into the pit greatly exceeds evaporation from the surface of the pit lake. The water level within the pit is likely to recover rapidly (within years) to pre-mining levels – with either high rainfall or surface water run-off contributing to the influx of water into the mine void. The resultant lake will act as a recharge area for the surrounding aquifer and water will flow radially out from the pit into the aquifer. Due to influxes of freshwater, salinity within the pit lake would not be expected to increase over time, nor result in an increase in salinity within the surrounding aquifer. Groundwater recharge is most likely to occur in areas of high rainfall (e.g. tropical zone of northern Australia) (see Case 3, Figure 6).

Figure 6: Hydrogeological Environments for Mine Voids

Figure reference: Johnson and Wright, (2003).

5.1.2 Estimated mine inflows

Estimates of potential groundwater inflows to the pit post-mining were made using a simple analytical groundwater flow model, using ranges of typical values for hydrogeological parameters based on site derived information and supplemented by our experience in similar hydrogeological environments. This approach provides broad “envelopes” of likely inflows and allows mine inflows to be characterised (i.e. groundwater sink, throughflow or recharge).

The estimated final pit elevations are presented in Figure 1 (as supplied by Penrice/ Mining Consultants in Dec 2012). Assessment of this shape of mine void is somewhat more complicated than for the majority of open cut mines, which more often than not tend to be conical in shape and as such can be represented by a large diameter well (of equivalent saturated volume). In this instance however, the mine void will essentially be a three-dimensional trapezoid in shape with rounded ends – as such both radial and parallel inflows needed to be considered.


A94D/R001a Page 17

Three methods have been adopted for this assessment including Armstrong (1987); Marrinelli Nicolli (2000) method (also used in Golder, 2008) for a circular pit and the circular pit method often used in mine void construction dewatering (Powers et. al, 2007). All models are based on a modification of the Dupuit-Forchheimer and Thiem Equations for flow to a well.

The favoured method for this investigation was developed is Armstrong (1987) which is specially aimed at assessing groundwater inflows into long pits. Flows to the pit void were calculated for an initial water level in the pit equivalent to the final pit base. The method makes a number of simplifying assumptions and cannot be considered to be precise. The model (and actual inflow rates in most situations) is particularly sensitive to aquifer permeability. The standard hydrogeological assumptions of a homogeneous and isotropic aquifer of infinite extent (ie. no boundaries) also apply. The models were run for the following derived and assumed average aquifer/climatic parameters:

Average minimum water table level of 165 m below ambient water levels.

A minimum saturated aquifer thickness of 300 m.

Average aquifer permeability (Kh) in the order of about 0.055 to 0.1 m/day is expected (note Kh values predicted by Golders (2008) were interpreted to be reflective of smaller evaporation based on the approximate radius of the current pit lake).

Evaporation rate of 1825 mm/yr and an evaporation efficiency of 1. It is normal practice to apply corrective pan factors of between about 0.5 and 0.8, to account for the depth of the pit causing both shading from radiant heat, and shielding from significant winds. In this case, however, the efficiency of 1 was applied because there is data available from the in-pit climate station.

Recharge of 60 mm/yr (based on Aquaterra 2009 study).

Current dewatering approximately 130 ML/year (356 kL/day).

Current licensed volume is 130.36 ML/year.

The mine inflow estimates for all three methods are presented in Figure 7.

5.1.3 Long term pit void

Water inflow to the final void post mining would consist of groundwater inflow, direct rainfall into the void and runoff from slopes draining into the void. This would be balanced (eventually) by evaporation at about 1825 mm/year. Water levels in the final void as predicted by the three methods used in this assessment (Figure 7) is expected to recover to about the current pit level (269 mAHD) in about 125 years. Initial recovery will take about 40 years to reach 80% of the final long term equilibrium level, and then the water levels within the final void will attain their post-mining equilibrium level somewhere between 275 and 285 mAHD in well over 150 years (Figure 8). At equilibrium, the amount of water inflow entering the void will be balanced by evaporation. The water level within the void would vary in height in response to climatic conditions notably the balance between rainfall and evaporation and since we cannot accurately predict the future conditions due to variability in the evaporation data along with other climate data, it is more reasonable to provide a range within which final equilibrium can be expected.

During early stages of post-mining recovery, there would be a steep hydraulic gradient between the water level in the final void and the groundwater levels within the surrounding aquifer (inferred by the red dotted line in Figure 9). The steep hydraulic gradient would result in maximum inflows to the final void. However, as the water level within the final void rises, the hydraulic gradient between the void and the surrounding aquifer would become shallower (blue and green dotted lines in Figure 9) resulting in a reduced inflow of groundwater into the void. The post mining regional groundwater flow pattern would largely re-establish based on the predicted pit lake level.

If the pit water level actually manifests in the upper end of the predicted range, then Figure 9 shows that the pit void lake would become a throughflow system, with some element of outflow towards the Barossa Basin. This means that the maximum salinity increase in the pit would asymptote to a stable value, as the outflow would also take with some salt (i.e an equilibrium salt balance would develop along with the water balance). It is recommended that this be investigated in detail in future work programs.

PROJECT: Penrice Quarry AngastoRPS

Aquaterra Job: A94D

Date: 8th January 2013

Groundwater Inflow Rate into Elongated Pit for Estimation of Terminal Pit Lake Level

Required inputs are in green fields (please don't change other cells)1 2 3

Hydraulic conductivity (m/d) 0.04 0.06 0.056

Saturated wall thickness (m) 18 18 18

Average lake depth (m) 13 13 13

Evaporation rate (mm/y) 1825 1825 1825

ET efficiency (0 to 1) 1 1 1

Recharge (mm/y) 60 60 60 Current Pit Level (267mAHD)Aquifer thickness (m) 165 165 165

Kh/Kv (for M-N method only) 5 Current Approval (243 mAHD)

1 2 3

Pit Dimensions Marinelli - Niccoli (2000) Armstrong (1987) Powers & al. (6.4)

Elevation Depth Length Width

rpit rw Evaporation Evaporation at

the current

sump

(200m x 50m) Walls Base

r0 Qgw Qgw - E time to

refill

r0 Qpar Qr Qgw Qgw - E time to

refill

r0 Qgw Qgw - E time to

refill

m m m m m kL/d kL/d L/s L/s m kL/d kL/d year m kL/d kL/d kL/d kL/d year m kL/d kL/d year

mRL316 35 1240 295 340 147.5 1,829 944 237 755 523 - 835 346 237 583 0 - 820 1,058 -304 45 1200 250 310 125 1,500 892 279 855 687 - 960 412 304 716 0 - 940 1,118 -281 70 1150 225 287 112.5 1,294 99 846 403 1120 1,165 - 1,285 605 554 1,159 - 1,255 1,327 33 1,146268 85 1040 195 254 97.5 1,014 789 434 1235 1,368 354 71 1,430 665 704 1,368 354 70 1,395 1,376 362 75256 95 1015 170 234 85 863 752 447 1310 1,497 634 24 1,520 718 797 1,515 652 23 1,480 1,374 511 33244 105 980 145 213 72.5 711 716 450 1380 1,608 897 14 1,605 760 886 1,646 936 14 1,560 1,354 643 22232 122 915 125 191 62.5 572 669 468 1505 1,832 1,260 9 1,760 829 1,080 1,909 1,337 9 1,710 1,348 777 16220 130 870 100 166 50 435 624 435 1530 1,829 1,394 4 1,795 834 1,122 1,956 1,521 4 1,745 1,287 852 8196 165 750 70 129 35 263 553 428 1760 2,225 1,963 3 2,075 925 1,529 2,455 2,192 3 2,020 1,180 918 6

12 316 35 4E+05 Recovery time

0

500

1,000

1,500

2,000

2,500

3,000

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180

Infl

ow

/ E

vap

ora

tio

n (

kL/d

)

Depth below ambient water level (m)

Powers (2007) Armstrong (1987) Marinelli, Niccoli (2000) Evaporation

Powers (2007) Amstrong (1987) Marinelli, Niccoli (2000) Evaporation

Current Approval ~ (RL 243) Current Pit Level~(RL 267)

Figure 7: Pit Inflow Calculations

LONG TERM PREDICTED POST MINING WATER LEVEL FIGURE 8

f:\jobs\a94\task_d\600\figures\figure 8.docx

PROJECT: Penrice Quarry Angaston RPS Aquaterra Job: A94D Date: 6th Feb. 2013

Figure 9: Penrice Groundwater Model

Elevation

(mAHD)

PENRICE GROUNDWATER MODEL

350

300

250

200

150

Predicted post-mining water level (between 275—285 mAHD)

Mined Quarry Pit Void

Future Mining

Bar

oss

a Se

dim

en

ts

Fractured Rock Aquifer

Obs #: MOR127

Elev: ~370 mAHD

RSWL: ~350 mAHD

Depth ~83 mAHD

Unit #: 6729-1677

Elev: ~323 mAHD

RSWL: ~307 mAHD

Depth ~45 mAHD

Obs #: MOR121

Elev: ~302 mAHD

RSWL: ~272 mAHD

Depth ~49 mAHD

Inferred Pre-Mining Topography

Current Pit Floor ( 267 mAHD)

LEGEND

Final Post-Mining Groundwater level

Current Groundwater level

Early Post-Mining Groundwater level

Predicted Pit water level


A94D/R001a Page 21

6. CONCLUSIONS AND RECOMMENDATIONS

6.1 Mine Operational Stage:

The CRD investigation revealed that groundwater levels in the fractured rock aquifer in the region display a close relationship with rainfall patterns. Dewatering of pit at the current pit floor level did not cause any significant change to groundwater levels in the surrounding aquifer. There is however some evidence of minor recession in groundwater levels in bore MOR126 located on the north of the mine site (within 1km) although it is not possible to determine if this is attributable to mine dewatering. The pit will remain as a groundwater sink during operational stage.

Although the predicted mine inflow rates cover a range (depending on the method and parameters assumed), the analytical model shows that the final mine (~243 mAHD) will require around two times more dewatering (and perhaps even more) than the amount of current dewatering of 356 kL/day. This will mean that an additional licence will be required to augment the current dewatering licence, in the order of 344 kL/day or 125.7 ML/year.

6.2 Post-Mining Void

The results of the analytical groundwater modelling indicate that the Penrice mine will become a local groundwater sink as the mine depth progresses towards the current approval level. Following mine closure, an in-pit lake is predicted to develop as the water level slowly recovers to around the level of the current pit floor, or higher (275 to 285 m AHD). As the long term post-mining groundwater level is predicted to recover above the current pit floor level (269 mAHD) to a level consistent with the current pit water level (279 mAHD), the impact on the surrounding aquifer will be similar to the current local scale minor impacts. It is predicted that when the pit lake reaches equilibrium (post-mining), the final pit lake level will be approximately the level at which groundwater throughflow should occur, which would reduce the potential for major salinity impacts (Figure 9).

6.3 Recommendation

To provide more detail on these assessments, further detailed investigations may be required, nominally including:

6.3.1 Numerical Modelling

It is apparent from the simple analytical models that the post mine pit void would likely represent a groundwater throughflow system or possibly a minor/local sink. However, due to the pre-mining steep hydraulic gradient and wide variation of pre-mining topographic height (390 m AHD to 310 m AHD) the status of the final pit lake cannot be predicted with certainty. To accurately predict the status of the pit lake a numerical model will be required. The numerical model will replicate the topography and hydrogeological condition of the site and may be used to more accurately determine the status of the post mine pit lake scenario.

6.3.2 Salinity of the pit lake

The impact on salinity on the surrounding aquifer is beyond the scope of the current investigation. To accurately determine the salinity impact, a numerical flow model would be required to more robustly define the final pit void condition.


Page 22 A94D/R001a

7. REFERENCES

Adelaide and Mount Lofty Ranges Natural Resources Management Board. 2006. Draft Barossa Water Allocation Plan. AMLRNRMB, October 2006.

Amstrong, D., 1987, Groundwater Flow Systems. Australian Groundwater School, 1987.

Aquaterra 2009, Penrice Quarry Angaston: Hydrogeological Assessment for the Mine Closure Planning, Adelaide, South Australia. Report prepared for Penrice Quarry and Mineral, Angaston, SA, October 2009.

Brown K.G., The Hydrogeology of the Barossa Basin, South Australia. The Department of Water, Land and Biodiversity Conservation, Report DWLBC 2002/18, 2002.

Cobb M. A., 1986, Groundwater Resources of the Barossa Valley, Departments of Mine and Energy Geological Survey of South Australia, Government Printer, South Australia.

Commander, D.P, Mills, C.H., and Waterhouse, J.D., 1994, Salinisation of mined-out pits in Western Australia: Conference proceedings of the XXV Congress of the International Association of Hydrogeologists, Adelaide, South Australia, November, 1994.

Doodley T., Evans T., Henschke C., Liddicoat C., 2003, North and South Para Salinity Management Plan, Department of Water Land and Biodiversity Conservation,

Department for Water, 2011, Barossa PWRA Groundwater level and salinity status report

Golder Associates, 2008, Groundwater Assessment – Penrice Quarry, Angaston, SA. Report prepared for Penrice Quarry and Mineral, Angaston, SA, October 2008.

Johnson, S.L., and Wright, A.H., 2003, Mine voids Mine void water resource issue in Western Australia. Western Australia, Water and Rivers Comission, Hydrogeological Record Series, Report HG 9, 93p, April 2003

Marinelli, F and Niccoli, W.L, 2000, Simple Analytical Equations for Estimating Groundwater Inflow into a Mine Pit. Groundwater Vol 38 No2, 99311-314

Powers, J.P. Corwin, A.B., Schmall, P.C., and Kaeck, W.E., 2007, Construction, Dewatering and Groundwater Control. John Wiley and Sons, Incorporated. Hobeken, New Jersey, USA.

APPENDIX A: CRD HYDROGRAPHS

F:\Jobs\A94\Task_D\300\360_Water_Levels\FRA\Scaled\[auto_hydrographs - Normanville Gp2.xls]Figure_01

CRD- Groundwater Level Relationship in Fractured Rock Aquifer FIGURE A.01

-400

-200

0

200

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800

363

364

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1970

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AH

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MOR124

Reduced Water LevelCRD

-400

-200

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200

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354

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MOR125




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MOR126


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372

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MOR129



CRD- Groundwater Level Relationship in Fractured Rock Aquifer A.03

-400

-200

0

200

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600

800

360

361

362

363

364

365

366

367

368

369

37019

68

1970

1972

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1976

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1981

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1985

1987

1989

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1994

1996

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2011

Cu

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tion

(m

m)

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AH

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Year

MOR130 Reduced Water LevelCRD

-400

-200

0

200

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600

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342

344

346

348

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356

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362

1968

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0

200

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280

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29019

68

1970

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MOR256


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F:\Jobs\A94\Task_D\300\360_Water_Levels\FRA\Scaled\[auto_hydrographs - Angaston Marble_.xls]Figure_01


-400.00

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0.00

200.00

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MOR127

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0.00

200.00

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F:\Jobs\A94\Task_D\300\360_Water_Levels\[auto_hydrographs Sedimentary.xls]Figure_01

CRD - Groundwater Relationship in the Barossa Sedimants - FIGURE A.06

-400

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270

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279

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1950 1960 1970 1980 1990 2000 2010

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D (

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)

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r L

evel (m

)

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MOR074 CRDMOR074 modelled

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Reduced WaterLevel

F:\Jobs\A94\Task_D\300\360_Water_Levels\[auto_hydrographs Sedimentary.xls]Figure_03


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F:\Jobs\A94\Task_D\300\360_Water_Levels\Hydrographs\[Unknown Aquifers.xls]Figure_01

CRD - Groundwater relationship for Unnamed Aquifers - FIGURE A.09

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1000

283285287289291293295297299301303

1977 1983 1988 1994 1999 2005 2010

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283285287289291293295297299301303

1977 1983 1988 1994 1999 2005 2010

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MOR123


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1967 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2013

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MOR264


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260262264266268270272274276278280

1977 1983 1988 1994 1999 2005 2010

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APPENDIX B: PENRICE IN-PIT EVAPORATION

ANALYSIS

F:\Jobs\A94\Task_D\600\M004a.docx Page 1

MEMORANDUM

COMPANY: Penrice

ATTENTION: James Rowe

FROM: James Ohanga/Subhas Nandy

DATE: 17 December 2012 JOB NO: A94D DOC NO: M004a

SUBJECT: Penrice In-Pit Evaporation Data and Relationship to Nuriootpa data

1. INTRODUCTION

This technical memo has been prepared for Penrice as an update to the analysis conducted on the in-pit evaporation data from the automated weather station at Penrice Quarry. The weather station was installed on advice of RPS Aquaterra to collect weather data, notably on evaporation, for use in hydrogeological assessments of the long term post-closure management options. For example, the analytical modelling of the post-closure water balance requires the estimation of groundwater inflows to the pit, as well as evaporation from a pit lake.

We understand that there have been operational problems with the weather station, and Penrice requested an assessment of the data to identify whether or not we have adequate data to benchmark against the Nuriootpa BoM station, and thus confirm whether the Quarry climate station could be decommissioned.

2. SITE SPECIFIC DATA

It is our understanding that the automated pit weather station has been experiencing some hardware problems with battery outages which affect the data collection process. The effect of low battery voltage is demonstrated in the brown plots on Figure 1 which shows either zero or unrealistically high evaporation data were recorded when battery voltage dropped. There were also periods when no data was logged; the longest data gap was between September 2011 and January 2012.

Figure 1: Effects of battery on Penrice Quarry evaporation data


The long term and cost effective solution to acquiring to site-specific evaporation data can be achieved by establishing an analytical relationship between the Quarry evaporation and the nearby Bureau of Meteorology (BOM) station data. The closest BOM station to Penrice Quarry that records evaporation data is Nuriootpa Viticultural, located about 5 km west of the Quarry.

Nuriootpa evaporation data was obtained for analytical comparison with the Penrice Quarry in-pit evaporation. The methods used for analysis were cumulative double mass curve technique and regression analysis.

3. DATA ANALYSIS

3.1 Double mass curve

A double-mass curve is used to demonstrate that data from a particular site is not subject to inconsistencies or non-linearities (e.g. due to site re-location or other influences). The analysis involves plotting a graph of the cumulative sum of values from one site against the cumulative sum of values of another site during the same period of time. The double mass data will plot as a straight line as long as the data are proportional.

The breaks (circled) in the double-mass curve Figure 2a are caused by inconsistencies in the Penrice data, compared to the reliable BoM data. After cleaning up the data first by excluding the periods when 0mm evaporation were recorded and the periods when evaporation data were recorded at Penrice that are much higher than typical daily evaporation rates (e.g. see Figure 1), were recorded, the resulting Figure 2b plots is a straight line which confirms consistency in quality-assured evaporation data between the two weather stations.

Figure 2a: All raw data Figure 2b: Cleaned up data

3.2 Regression analysis

Linear regression analysis of the cleaned up data was conducted to establish the analytical relationship between Penrice Quarry evaporation and Nuriootpa Viticultural station evaporation. The result was a regression plot with a correlation of determination (R

2) of 0.5792 (Figure 3a). In order to get a better

correlation, data that seemed to be out of range (marked in red, indicating a physically unrealistic ratio of evaporation data between the two sites) were excluded from analysis, which resulted in improved R

2

value; R2 = 0.7256 = 0.7256 (Figure 3b).

The relationship between Penrice Quarry and Nuriootpa evaporation is thus established as:

Y = 1.155X (R2 = 0.726)

where: Y is Penrice Evaporation and X is Nuriootpa Evaporation.

Pen

ric

e Q

uarry (

mm

)

Nuriootpa Viticultural (mm)

Cumulative Double Mass Curve (Penrice VS Nuriootpa Evaporation )


Figure 2a: R2 = 0.5792 Figure 2b: R2 = 0.7256

4. Conclusion and Recommendation

Penrice Quarry automated weather station has provided objective data on the unique weather conditions in the quarry pit. One interesting finding is the fact that in-pit evaporation is generally higher than Nuriootpa Viticultural evaporation, by about 15%. It is not possible, nor is it necessary for the purpose of the hydrological study to establish exactly the reasons why this is so, although it could be hypothesised as due in part to the properties of the quarry surface which may absorb and/or emit more heat energy from the sun hence causing higher evaporation.

Given the technical issues that have plagued the Penrice Quarry in-pit weather station and that we now have established an analytical relationship benchmarked to the Nuriootpa BoM station, it may be cost effective to decommission the Penrice weather station. Data from the nearby Nuriootpa Viticultural BOM station can be applied to the established analytical equation to derive in-pit evaporation rates for use in hydrological analysis. We can therefore recommend decommissioning of the in-pit weather station.

Yours sincerely, RPS Aquaterra

James Ohanga Subhas Nandy Hydrogeologist Senior Modeller/Hydrogeologist

APPENDIX C: WATER ALLOCATION DATA

PENRICE QUARRY – HYDROGEOLOGICAL INVESTIGATION

Water allocations for bores near Penrice Quarry (www.WaterConnect.sa.gov.au)

Unit Number Parcel Number

PURPOSE Total Water allocation per

year (KL)

Licence Number

FRACTURED ROCK AQUIFER

6728‐2021 CT 5092 628 IRR 9300 3902‐0

6729‐930 CT 5122 506 DOMIRR, STK 44000 3391‐0

6729‐391 CT 5179 936 IRR 49900 3784‐0

6729‐1580 CT 5184 154 IRR 40500 3748‐0

6729‐985 CT 5240 2 IRROBS 6800 3728‐2

6728‐2294 CT 5263 645 IRR 44342 3898‐1

6728‐3254 CT 5313 641 IRR 205910 3871‐0

6728‐3310 CT 5315 955 IRR 3600 3895‐0

6729‐537 CT 5337 87 IRR 23500 3693‐0

6728‐2515 CT 5360 792 IRR 11000 3909‐0

6728‐1824 CT 5366 749 IRR 14500 3753‐0

6728‐2494 CT 5418 920 IRR 11700 4088‐0

6729‐893 CT 5463 172 IRROBS 13400 3889‐0

6728‐1997 CT 5486 385 STK 16830 3908‐0

6729‐1124 CT 5544 448 IRR 26100 3681‐0

6728‐3297 CT 5584 977 IRR 18224 4084‐0

6729‐1118 CT 5600 888 IRR 10000 3893‐0

6728‐2530 CT 5618 780 IRR 4100 3906‐0

6729‐1717 CT 5630 137 MON 3080 129797‐0

6729‐1382 CT 5671 415 IRR 8100 3725‐2

6729‐1532 CT 5706 148 OBSREC 10900 3688‐1

6728‐2280 CT 5732 145 IRR 18224 4084‐0

6728‐3065 CT 5732 146 IRR 18225 4084‐0

6728‐2653 CT 5752 488 IRR 6100 3885‐1

6728‐2022 CT 5777 718 IRR 41720 3888‐0

6728‐2080 CT 5783 736 IRROBS 249000 3794‐0

6728‐3513 CT 5811 840 IRR 16830 3908‐0

6728‐2599 CT 5814 10 IRR 11000 3910‐0

6729‐499 CT 5818 694 IRR 163387 4066‐0

6728‐2643 CT 5822 448 DEPIRR 16830 3908‐0

6728‐1922 CT 5835 202 IRR 87211 3894‐1

6728‐2030 CT 5843 621 INDIRR 55330 3913‐0

6728‐3152 CT 5846 685 IRR 3250 137042‐0

6728‐2695 CT 5846 686 IRR 4730 3905‐1

6729‐1557 CT 5856 285 IRR 43000 3907‐0

6729‐1434 CT 5902 905 IND 4000 3825‐0

6728‐2470 CT 5910 167 IRROBS 11300 3731‐0

6729‐1120 CT 5962 464 IRR 102200 3778‐0

PENRICE QUARRY – HYDROGEOLOGICAL INVESTIGATION

Unit Number Parcel Number

PURPOSE Total Water allocation per

year (KL)

Licence Number

6729‐1120 CT 5962 464 IRR 28160 3724‐0

6729‐1593 CT 5973 931 IRR 69500 3907‐0

6728‐2024 CT 5986 341 IND 8000 3897‐1

SEDIMENTARY AQUIFER

6629‐80 CT 5979 904 IRROBS 20200 3603‐0

6729‐1179 CT 5561 179 IRROBS, REC 51100 3764‐0

6729‐622 CT 5360 359 IRROBS 4900 3695‐0

6729‐610 CT 5126 904 IRROBS 7100 3665‐0

6729‐567 CT 5694 29 IRROBS 16200 3761‐0

6729‐531 CT 5497 61 IRROBS 35400 3694‐1

6729‐1496 CT 5898 850 IRROBS 15500 3786‐0

6729‐584 CT 5814 184 IRROBS 12200 3691‐0

6729‐720 CT 3344 162 IRR 127300 3770‐0

6729‐1123 CT 5711 483 IRR 37300 3689‐0

6729‐1163 CT 5730 686 IRR 6800 3692‐0

6729‐1428 CT 5383 861 IRR 30500 3788‐0

6729‐1445 CT 5699 158 IRR 19100 3712‐1

6729‐1499 CT 5645 346 IRR 23300 3676‐0

6729‐1500 CT 5382 171 IRR 23600 3716‐0

PENRICE MINE - HYDROGEOLOGICAL INVESTIGATION

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