appendix 4-7 tsf design report
TRANSCRIPT
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YANGIBANA RARE EARTHS PROJECT
TSF DESIGN DEVELOPMENT – PRE-CONSTRUCTION
REPORT
DOCUMENT NO.: YGB-31-100-ENG-CIV-REP-0001
REVISION DATE ISSUED FOR PREPARED BY REVIEWED BY APPROVED BY
A 15/03/19 Draft Issued for Review B. Haslow GHD Pty Ltd
B. Haslow GHD Pty Ltd
00 01/04/19 Issued for Use B. Haslow GHD Pty Ltd
B. Haslow GHD Pty Ltd
01 05/06/19 Re-Issued for Use B. Haslow GHD Pty Ltd
B. Haslow GHD Pty Ltd
02 02/09/20 Re-Issued for Use B. Haslow GHD Pty Ltd
B. Haslow GHD Pty Ltd
Hastings Technology Metals Limited Yangibana TSF Design Development
Pre-Construction Report YGB-31-100-ENG-CIV-REP-0001 August 2020 Revision 2
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | i
Table of contents 1. Introduction .................................................................................................................................... 1
1.1 Overview .............................................................................................................................. 1
1.2 Purpose of the report ........................................................................................................... 1
1.3 Limitations ............................................................................................................................ 1
2. Background .................................................................................................................................... 3
2.1 General ................................................................................................................................ 3
2.2 Site location ......................................................................................................................... 3
2.3 Site condition and topography ............................................................................................. 3
2.4 Climate ................................................................................................................................. 4
2.5 Geology ................................................................................................................................ 5
2.6 Geotechnical investigations ................................................................................................. 5
2.7 Hydrogeology and groundwater ........................................................................................... 6
2.8 Hydrology ............................................................................................................................. 8
2.9 Seismicity ............................................................................................................................. 8
2.10 Mining .................................................................................................................................. 8
2.11 Processing and tailings waste streams ................................................................................ 8
3. Design refinement opportunities .................................................................................................. 10
4. Basis of Design ............................................................................................................................ 14
4.1 Design reference documentation ....................................................................................... 14
4.2 Basis of design parameters ............................................................................................... 16
5. Tailings characterisation .............................................................................................................. 18
5.1 Tailings testing ................................................................................................................... 18
5.2 Physical properties ............................................................................................................. 19
5.3 Geochemical characterisation ........................................................................................... 21
6. Design development concept ....................................................................................................... 35
6.1 General arrangement ......................................................................................................... 35
6.2 Concept details .................................................................................................................. 36
6.3 Water management ........................................................................................................... 37
6.4 Environmental risk and mitigation measures ..................................................................... 38
6.5 Closure and rehabilitation concept .................................................................................... 41
7. Consequence based design requirements .................................................................................. 44
7.1 General .............................................................................................................................. 44
7.2 DMIRS TSF characterisation ............................................................................................. 44
7.3 ANCOLD consequence category ....................................................................................... 45
7.4 Category based design criteria .......................................................................................... 46
8. Pre-construction design details ................................................................................................... 48
8.1 Construction materials and site clearing ............................................................................ 48
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8.2 Beneficiation TSF ............................................................................................................... 48
8.3 Hydromet TSF .................................................................................................................... 51
9. Specific design studies ................................................................................................................. 56
9.1 Stormwater storage assessment ....................................................................................... 56
9.2 Flood hydrology ................................................................................................................. 57
9.3 Water balance .................................................................................................................... 60
9.4 Seepage analysis ............................................................................................................... 63
9.5 Stability analysis ................................................................................................................ 65
9.6 Seismic assessment .......................................................................................................... 68
9.7 Hydromet TSF ammonia gas air emissions study ............................................................. 69
10. Operations, maintenance and surveillance .................................................................................. 71
10.1 Observational approach ..................................................................................................... 71
10.2 Monitoring and surveillance ............................................................................................... 71
10.3 Operation, maintenance and surveillance manual ............................................................ 73
10.4 Dam safety emergency plan .............................................................................................. 74
10.5 Annual audits ..................................................................................................................... 74
10.6 TSF operator training ......................................................................................................... 74
10.7 Temporary mining and plant shutdown provisions ............................................................ 75
11. References ................................................................................................................................... 76
Table index Table 2-1 Falling head in situ permeability test results (ATCW, 2019) ................................................ 6
Table 2-2 Water test results (ATCW, 2019) ......................................................................................... 6
Table 2-3 Storage volume requirement estimates ............................................................................... 9
Table 2-4 Potential water release ........................................................................................................ 9
Table 4-1 Standard documentation .................................................................................................... 14
Table 4-2 Hastings provided documentation ..................................................................................... 15
Table 4-3 Basis of design parameters ............................................................................................... 16
Table 4-4 TSF design characteristics ................................................................................................ 17
Table 5-1 Previous testing summary ................................................................................................. 18
Table 5-2 Testing physical characterisation test results .................................................................... 19
Table 5-3 Beneficiation tailings assumed physical properties ........................................................... 20
Table 5-4 Hydromet tailings assumed physical properties ................................................................ 20
Table 5-5 TSF 1 and 2 geochemical analysis summary .................................................................... 22
Table 5-6 Summary of geochemical test work ................................................................................... 22
Table 5-7 Summary of total metal (ICPMS) concentration and GAI values* ..................................... 24
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Table 5-8 LEAF leach and pore water compared to ANZECC and ARMCANZ livestock guidelines (2000) ............................................................................................................... 28
Table 5-9 LEAF leach and pore water compared to NEPM drinking water and fresh water
guidelines (2013) ............................................................................................................... 29
Table 5-10 Summary of Beneficiation TSF characterisation* .............................................................. 31
Table 5-11 Evaporation pond and TSF 3 geochemical analysis summary* ........................................ 32
Table 5-12 Mass balance of Hydromet TSF* ....................................................................................... 33
Table 5-13 Summary of Hydromet TSF 3 characterisation ................................................................. 34
Table 5-14 Summary of key analytes for the TSFs* ............................................................................ 34
Table 6-1 Beneficiation decant recovery ............................................................................................ 37
Table 6-2 Tailings liquor concentrations exceeding reference values ............................................... 40
Table 6-3 TSF closure specification ................................................................................................... 41
Table 7-1 DMIRS TSF characterisation ............................................................................................. 44
Table 7-2 Design criteria from consequence category ...................................................................... 47
Table 8-1 Beneficiation TSF starter embankment geometry ............................................................ 48
Table 8-2 Hydromet TSF starter embankment geometry .................................................................. 51
Table 9-1 Freeboard and stormwater storage requirements ............................................................. 57
Table 9-2 Cut-off drain design parameters ........................................................................................ 59
Table 9-3 Hydromet TSF data ............................................................................................................ 60
Table 9-4 Tailings material and bleed water data .............................................................................. 60
Table 9-5 Climate input data .............................................................................................................. 60
Table 9-6 Simulation settings ............................................................................................................. 61
Table 9-7 Model hydraulic conductivity values .................................................................................. 63
Table 9-8 Stability analysis FOS acceptance criteria ........................................................................ 66
Table 9-9 Parameters used for stability analyses .............................................................................. 66
Table 9-10 Results of stability analysis ................................................................................................ 67
Table 10-1 TSF inspection types and frequency ................................................................................. 71
Table 10-2 TSF monitoring types and frequency ................................................................................. 72
Figure index
Figure 2-1 Yangibana project location (ATCW, 2019) .......................................................................... 3
Figure 2-2 TSF site setting .................................................................................................................... 4
Figure 2-3 Conceptual hydrogeological model for TSF site (ATCW, 2019) .......................................... 8
Figure 3-1 General arrangement of FS concept plan (ATCW 2019) .................................................. 10
Figure 3-2 Proposed pre-construction design concept general arrangement .................................... 12
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Figure 3-3 FS concept (red) versus refined pre-construction concept (green) .................................. 13
Figure 5-1 Metal concentration at varying LEAF pH conditions .......................................................... 27
Figure 6-1 General arrangement of TSFs (after 3 years) ................................................................... 35
Figure 6-2 Watercourses and catchment area division around TSF site ............................................ 38
Figure 6-3 TSF closure concept general arrangement ....................................................................... 43
Figure 6-4 TSF concept capping design ............................................................................................ 43
Figure 8-1 Beneficiation TSF storage curve ....................................................................................... 49
Figure 8-2 Beneficiation TSF embankment typical section ................................................................. 49
Figure 8-3 Hydromet TSF embankment typical section ...................................................................... 52
Figure 8-4 Megaflo panel drain examples (courtesy Geofabrics Australia) ........................................ 53
Figure 9-1 ANCOLD freeboard definition ............................................................................................ 56
Figure 9-2 Design rainfall IFD curves .................................................................................................. 58
Figure 9-3 Hydromet TSF hydrograph (critical duration) .................................................................... 58
Figure 9-4 Beneficiation TSF hydrograph (critical duration) ............................................................... 59
Figure 9-5 Overall hydromet TSF inventory ........................................................................................ 62
Figure 9-6 HW/MW vertical seepage rates ......................................................................................... 64
Figure 9-7 Stability model section ....................................................................................................... 65
Figure 9-8 Relative crest settlement versus peak ground acceleration (ATCW, 2019) ...................... 68
Figure 9-9 Ammonia/ammonium concentration vs pH (Richard, 1996) .............................................. 70
Appendices Appendix A – Design Drawings
Appendix B – Tailings Test Results – Geotechnical
Appendix C – Combined Beneficiation Tailings Test Results - Geochemical
Appendix D – Seepage Analysis
Appendix E – Stability Analysis
Appendix F – Consequence Category Assessment
Appendix G – Environmental Benefits Summary Table
Appendix H – Example Geosynthetic Liner Specification
Appendix I – Ammonia Gas Modelling Reports
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 1
1. Introduction1.1 Overview
Hastings Technology Metals Limited (Hastings) is progressing the design and approvals associated with the Yangibana Rare Earths Project (Yangibana Project) in the Gascoyne region
of WA.
A Feasibility Study (FS) has been completed for the project (ATCW, 2019), including concept design of Tailings Storage Facilities (TSFs) and an evaporation pond.
The proposed ore processing concept resulted in three distinct tailings streams as follows:
Tailings from beneficiation plant Rougher and Cleaner 1 flotation cells
Tailings from beneficiation plant Cleaner 2 to Cleaner 4 flotation cells
Tailings (combined residue) from hydrometallurgical (Hydromet.) plant
In addition, the need for an evaporation pond was identified to dispose of spent liquor from the
Hydromet plant together with brine from the RO water treatment plant.
The resulting concept design featured three separate TSFs and an evaporation pond. Following
a review of the Feasibility Study concept design, a number of opportunities for design
development were identified by GHD. This report further explores these opportunities and
develops a Pre-Construction Design to progress project approvals.
1.2 Purpose of the report
The purpose for this report is to describe the opportunities for refinement of the Feasibility
Study concept design, and to present an updated pre-construction design for disposal of
flotation tails from the Beneficiation Plant and residue and spent liquor from the Hydromet plant.
Design studies have been completed to a pre-construction level, for inclusion in EPA Approvals
documentation, Mining Proposal, and Works Approval documentation.
1.3 Limitations
This report has been prepared by GHD for Hastings Technology Metals Limited and may only be used and
relied on by Hastings Technology Metals Limited for the purpose agreed between GHD and the Hastings
Technology Metals Limited as set out in section 1 of this report.
GHD otherwise disclaims responsibility to any person other than Hastings Technology Metals Limited
arising in connection with this report. GHD also excludes implied warranties and conditions, to the extent
legally permissible.
The services undertaken by GHD in connection with preparing this report were limited to those specifically
detailed in the report and are subject to the scope limitations set out in the report.
The opinions, conclusions and any recommendations in this report are based on conditions encountered
and information reviewed at the date of preparation of the report. GHD has no responsibility or obligation to
update this report to account for events or changes occurring subsequent to the date that the report was
prepared.
The opinions, conclusions and any recommendations in this report are based on assumptions made by
GHD described in this report. GHD disclaims liability arising from any of the assumptions being incorrect.
GHD has prepared this report on the basis of information provided by Hastings Technology Metals Limited
and others who provided information to GHD (including Government authorities), which GHD has not
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 2
independently verified or checked beyond the agreed scope of work. GHD does not accept liability in
connection with such unverified information, including errors and omissions in the report which were
caused by errors or omissions in that information.
GHD has prepared the preliminary cost estimates using information reasonably available to the GHD
employee) who prepared this report; and based on assumptions and judgments made by GHD
The Cost Estimate has been prepared for the purpose of comparison of options and must not be used for
any other purpose.
The Cost Estimate is a preliminary estimate only. Actual prices, costs and other variables may be different
to those used to prepare the Cost Estimate and may change. Unless as otherwise specified in this report,
no detailed quotation has been obtained for actions identified in this report. GHD does not represent,
warrant or guarantee that the [works/project] can or will be undertaken at a cost which is the same or less
than the Cost Estimate.
Where estimates of potential costs are provided with an indicated level of confidence, notwithstanding the
conservatism of the level of confidence selected as the planning level, there remains a chance that the
cost will be greater than the planning estimate, and any funding would not be adequate. The confidence
level considered to be most appropriate for planning purposes will vary depending on the conservatism of
the user and the nature of the project. The user should therefore select appropriate confidence levels to
suit their particular risk profile.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 3
2. Background2.1 General
Background information has been presented in detail in the TSF Concept Design Report
(ATCW, 2019). A summary of background data is presented in the following sections to assist with the reader’s understanding.
2.2 Site location
The Yangibana Project is located in the Gascoyne region of Western Australia, approximately 270 km northeast of Carnarvon. Figure 2-1 below shows the site location.
Figure 2-1 Yangibana project location (ATCW, 2019)
2.3 Site condition and topography
The proposed TSF is located in an area of undulating topography where a number of small gullies are formed between subtle rises at ground level. These gullies are initially utilised to form
the TSF embankments. The TSF site is located between two existing tributaries of Fraser Creek. To the east and south of the TSF the natural ground continues to rise to a ridge line that exists at around RL350 (approximately 20 m higher elevation than the TSF crest). The small
catchment between this ridge and the TSF is managed by the construction of a diversion channel. A locality plan is shown in Figure 2-2.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 4
Figure 2-2 TSF site setting
2.4 Climate
The Köppen-Geiger climate classification denotes the TSF area as being within the BWh
climate zone (Peel et al. 2007) which is considered to be an arid and semi-arid climate with an
average annual temperature above 18°C. The area is typically impacted by the west coast
trough, northwest cloudbanks, tropical cyclones, frontal systems and a subtropical ridge (Bureau
of Meteorology [BoM] 2010).
The west coast trough is a semi-permanent climatic feature with a dominating effect on weather
conditions during the warmer months in the southwest of Western Australia. The trough is a low
pressure zone that develops at the boundary between the warm continental easterly winds and
cooler maritime winds from the Indian Ocean. While the trough development depends on
prevailing conditions, however it is generally noted that areas to the east of the trough
experience hot days in excess of 40°C, thunderstorms and heavy rainfall, with areas to the west
experiencing milder conditions (Bureau of Meteorology [BoM] 2010).
Similarly to the west coast trough, the northwest cloudbanks are also active during the warmer
months forming when moist tropical air from the Indian Ocean moves south-eastward, and is
forced to rise over the colder mid latitude air. Widespread heavy rain can be expected with the
northwest cloudbanks (Bureau of Meteorology [BoM] 2010).
The cyclone season is officially from November to April although there tends to be fewer
cyclones early in the season. Destructive winds and high rainfall can be associated with tropical
cyclones (Bureau of Meteorology [BoM] 2010).
Frontal systems are known to impact the TSF area with cold fronts bringing rainfall for extended
periods of up to a week. The subtropical ridge discussed previously suppresses frontal activity
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during the warmer months while in winter the ridge moves over central Australia, permitting cold fronts to extend further northwards (Bureau of Meteorology [BoM] 2010).
Given the number of climate influence that may be active and affecting the study area, it is unsurprising that the rainfall is erratic and bimodal (i.e. occurring in both winter and summer) (Desmond et al. 2001; Kendrick 2002).
The mean daily temperature recorded by the closest full suite weather station, Mount Phillips Station (station number 007058), ranges from 9°C in July to 40°C in January. The closest rainfall recording station, Wanna Station (station number 007028), indicates an average rainfall
of 244.9 mm with a maximum annual rainfall of 550 mm in 1999.
2.5 Geology
The geology within the area is dominated by Pimbyana Granite and Yangibana Granite. Meta-
sedimentary rocks including sandstones, calcareous-silicates and schists also occur across the site (ATCW, 2019). The granite in the area is well exposed forming the gently undulating topography across the tenement.
The near surface expression of the fenitised ferrocarbonatite sills/dykes is represented by sinuous veins of ironstones primarily of magnetite composition.
Geological investigations have found localised deposits of unconsolidated silt, sand and gravel
in the creeks crossing the site and calcrete deposits locally present adjacent to the alluvial channels.
2.6 Geotechnical investigations
ATCW completed a geotechnical investigation at the previously proposed TSF and evaporation pond sites in late 2016, in conjunction with further investigations for the additional site infrastructure locations. The geotechnical investigation report undertaken by ATCW can be
found in Appendix C of ATCW FS Concept Design Report. The locations of the exploratory test pits and boreholes are illustrated in Figure 14 of the ATCW Preliminary Design Report.
2.6.1 General soil profile
ATCW found the ground conditions observed across the site generally comprised a thin cover of
clayey sand with minor gravel overlying residual clayey and sandy gravels. Granite was exposed at ground surface in elevated areas across the site.
2.6.2 Residual soils / extremely weathered
The investigation found that below the clayey sand layer a dense clayey gravel was
encountered. In many places, the clay content decreased with depth, grading to sandy gravel.
The clayey gravel was considered fine to coarse, with occasional sub angular and angular cobbles, whereas the sandy gravel was typically fine to coarse, pale brown, with minor clay and
trace angular cobbles. ATCW found the moisture content of the residual soil was below 10%.
2.6.3 Granite
Refusal of the test pits undertaken by ATCW was found to be between 0.1 m and 2.4 m. Near surface rock was generally high to moderately weathered, the strength of the rock was
assessed as low to medium strength.
Boreholes around the Beneficiation TSF found that significant weathering in the granite was limited to 10 m. The granite was found to be pale grey and porphyritic with minor black crystals
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 6
of mafic minerals. The rock jointing was considered tight and rough with pale brown staining primarily in the upper weathered zones.
2.6.4 In situ permeability testing
During the borehole drilling at the Beneficiation TSF site, falling head permeability testing was undertaken with results tabulated below in Table 2-1.
Table 2-1 Falling head in situ permeability test results (ATCW, 2019)
Test Pit ID Depth Permeability K (m/s) Material
CTBH-01 0.00 – 6.60 m 1.14 x 10-07 HW Granite
CTBH-01 0.00 – 1.50 m 2.95 x 10-08 Clay / EW Granite
CTBH-02 0.00 – 1.60 m 1.57 x 10-07 EW / MW Granite
CTBH-02 0.00 – 5.60 m 1.40 x 10-08 EW / MW Granite
CTBH-03 0.00 – 6.55 m 7.44 x 10-09 Clay / Clayey Sand
CTBH-03 0.00 – 0.90 m 2.06 x 10-07 Clayey Sand / EW / MW Granite
CTBH-04 0.00 – 10.70 m 1.12 x 10-06 HW / SW Granite
CTBH-05 0.00 – 11.85 m 1.65 x 10-06 HW / SW Granite
Packer testing was also undertaken on boreholes CTBH-01 & CTBH-03, the results of which are
summarised in Table 2-2. The permeability values as interpreted by ATCW from the Lugeon test results are included.
Table 2-2 Water test results (ATCW, 2019)
Borehole ID
Test Type Test Interval (m)
Permeability k (m/s)
Lugeon Value
Material
CTBH-01 Falling Head 9.8 – 22.2 1.0 x 10-07 - SW Granite
CTBH-01 Falling Head 23.3 – 37.2 2.3 x 10-07 - FR Granite
CTBH-01 Constant Head 22.6 – 36.5 9.2 x 10-06 - FR Granite
CTBH-03 Constant Head 9.5 – 21.5 3.5 x 10-06 - SW Granite
CTBH-03 Lugeon 9.5 – 55.5 3.9 x 10-08 0.3 MW/FR Granite
CTBH-03 Lugeon 26.6 – 39.2 6.4 x 10-09 0.049 MW/SW Granite
2.7 Hydrogeology and groundwater
2.7.1 Regional hydrogeology
The regional hydrogeology of the area has been described by Groundwater Resource Management (GRM 2017). The model was derived from publically available datasets and a desktop assessment (ATCW, 2019).
The hydrogeology of the area is characterised by a south westerly draining system, coincident with the Lyons river surface water catchment. Alluvial cover is typically thought to be thin across most of the catchment but thickens towards the creeks and major drainage lines.
The hydrogeological conceptual model identified three hydrogeological units:
HU1 – Comprised of alluvium and calcrete thought to be discontinuous across the broader
project area. The alluvium is typically absent or less than a few metres thick and occupies
low lying areas in creeks and drainage channels. Calcrete is known to occur adjacent to
major drainage features (Lyons and Edmonds Rivers) and can be up to 30 m thick.
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HU2 – This comprises discrete ironstone units within the surrounding fresh bedrock. Theironstone units are narrow, regionally extensive and pinch and swell along strike and with
depth. Groundwater yields are generally low to moderate, however storage within the unit islikely to be low given the discrete nature of the units.
HU3 – Comprised of granites, granodiorite, and monzonites which from the hangingwall
and footwall of HU2 when they are in contact. The permeability of the units is very low withlow storage characteristics. Drill hole data from around Frasers and the TSF site suggestthat the weathering profile is relatively shallow, generally less than 10 m.
Recharge to the aquifer system is likely to occur predominately by stream flow from the
dominant creeks and tributaries and through direct rainfall.
A search of registered bores within a 20 km radius of Bald Hill was conducted using the Water
Information reporting database, which indicated that there were 15 bores within this radius. The
closest registered bore to Frasers Pit was approximately 5 km to the west and whilst it is listed
as being of unknown type, it is assumed, based on surrounding land use type, to be used for
livestock watering.
2.7.2 TSF site hydrogeological conditions
Geotechnical investigations were carried out within the immediate vicinity of the proposed TSF
site by ATCW in 2016, as reported in ATCW 2017. This included excavation of numerous test
pits and a drilling investigation using both diamond coring and reverse circulation methods with
associated packer and falling head testing. The ground conditions identified across the site
were reported as generally comprising a thin superficial cover of clayey sand with minor gravel
overlying residual clayey and sandy gravels derived from weathering of the underlying granite
rock mass. Granite was exposed at ground surface in most of the elevated site areas. The
depth of weathering in the rock mass was variable but typically the material became slightly
weathered at depths of less than 10 m.
These investigations were used to develop a conceptual site hydrogeological model (ATCW
2019). A typical conceptual hydrogeological model for the site is shown below in Figure 2-3.
This model has been utilised for the development of the pre-construction design.
Groundwater samples recovered from the vicinity of the Bald Hill and Frasers pits were fresh to
slightly brackish with TDS between 920 mg/l and 1,200 mg/l.
Groundwater sampled by ATCW from eight pastoral bores in the vicinity of the mine in 2015 had
TDS of 600 mg/l and 920 mg/l in two shallow alluvial bores (i.e. Contessi Bore and Minga Well),
and ranged from 1,400 mg/l to 2,800 mg/l in the remaining bores, believed to be installed into
fractured rock.
Drawdown modelling completed by GRM for dewatering of the Bald Hill and Frasers pits,
indicates the proposed TSF site is likely to be outside of the drawdown influence from the Frasers pit.
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Figure 2-3 Conceptual hydrogeological model for TSF site (ATCW, 2019)
2.8 Hydrology
A hydrological assessment undertaken by JDA consultant hydrologists found that the catchment
drains towards Lyon River, with the dominant drainage feature near the TSF area being Frasers
Creek passing to the western side of the TSF area (ATCW, 2019).
Assessment to-date has identified that the TSF area would not be adversely affected by flooding
of local drainage lines following rainfall associated with storm events up to 1:100 year ARI
(ATCW, 2019). Further findings of the hydrological assessment regarding additional
infrastructure are defined in the JDA report.
2.9 Seismicity
Based on the Geoscience Australia seismic hazard map, the site is in an area of moderate
seismicity (ATCW, 2019).
2.10 Mining
Hastings plan to undertake mining in multiple stages in open pits using drill and blast methods,
with Bald Hill, Frasers and Yangibana North/West ore deposits being the priority pits for initial
mining development (ATCW, 2019).
The TSF design will cater for a mine life of 10 years with a mining rate of 1 MtPa. For the
purposes of TSF design, a mine life of 10 years has been considered.
Waste rock landforms consisting primarily of slightly weathered to fresh granite will be located
on the northern footwall side of the pits. The saprolitic material at Bald Hill will be stockpiled
separately and may be used as low permeability material for TSF construction (ATCW, 2019
and Hastings verbal confirmation).
2.11 Processing and tailings waste streams
Three tailings streams are expected from the proposed processing route (ATCW, 2019) as
follows:
Tailings from beneficiation plant Rougher and Cleaner 1 flotation cells. This represents 95%
of the total beneficiation plant tailings stream (or 88% of total tailings).
Tailings from beneficiation plant Cleaner 2 to Cleaner 4 flotation cells. This represents less
than 5% of the total beneficiation plant tailings stream (or 4.5% of total tailings).
Downstream Tributary of Fraser Creek
Ridgeline TSF Location
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Tailings (combined residue and solution) from hydrometallurgical (Hydromet.) plant. This
represents approximately 7% of the total tailings produced.
Wastewater from the hydrometallurgical process and reverse osmosis effluent from the water treatment plant will not be of suitable quality for re-use in the processing circuits and will need to be evaporated as barren liquor. The estimated production rates of the various waste materials
were estimated by ATCW as summarised in Table 2-3 and Table 2-4. Note that these estimates are net values and do not include any contingency.
Table 2-3 Storage volume requirement estimates
Tailings Type Inflow
Solids
Content
Annual
Productio
n Solids
(t)
Mass
Water in
Slurry (t)
Assumed
In Situ Dry
Density
(t/m3)
Expected
Annual In
situ
Volume
(m3)
Total
Storage
Required
for LOM
(m3)
Bene Plant
Rougher and
Cleaner 1
49% 927,600 965,500 1.60 579,700 5,797,600
Bene Plant Cleaner 2,
3, 4
8% 47,500 116,000 0.75 63,200 632,000
Hydromet Plant
Residue
45% 62,500 93,500 0.50 124,800 1,248,000
Hydromet Plant
Scrubbing
Effluent
35% 11,000 20,500 0.50 22,000 221,000
Barren Liquor 0% 434,500 1.00 434,500 NA
Combined
Hydromet Waste
11% 72,000 550,000 0.50 144,000 1,440,000
Combined Bene
Plant Waste
52%
(Note 1) 975,000 900,000 1.50 650,000 6,500,000
Note 1 – Tailings solids content as advised by Hastings 28th March 2019 based on thickening test work.
Table 2-4 Potential water release
Tailings Type SG Solids Volume Solids (m3/a)
Volume Retained Water (m3/a)
Volume Water Released (m3/a)
Bene Plant Rougher and Cleaner 1
3.3 281,000 298,500 668,800
Bene Plant Rougher and Cleaner 2 - 4
3.22 14,700 48,500 67,500,
Hydromet Plant Residue
3.16 19,700 105,000 -11,455
Hydromet Plant Scrubbing Effluent
3.16 3,500 18,600 1,900
Combined Hydromet Waste
3.16 22,700 121,000 428,900
Combined Bene Plant Waste
3.3 295,500 354,500 545,500
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3. Design refinement opportunitiesGHD Technical Memorandum dated 6th February 2019, “Options Assessment Memorandum” presented a proposed refined concept design for tailings management for the Yangibana
project.
The ATCW FS concept design tailings strategy to date was to construct 5 storage dams as follows:
TSF 1 to receive beneficiation plant Rougher and Cleaner 1 flotation cells tailings. TSF 1
was proposed as a central thickened discharge facility.
TSF 2 to receive beneficiation plant Cleaner 2 to Cleaner 4 flotation cell tailings. TSF 2 was
proposed as a paddock type facility with spigotted perimeter discharge.
TSF 3 to receive combined residue and solution from the hydromet plant. TSF 3 is
proposed as a paddock type facility with spigotted perimeter discharge. A BGM liner and
underdrainage system was proposed.
Return Water Pond (RWP) for storage of run-off and decant waters removed from TSF 1
and TSF 2. The WRP has an upstream clay zone and cut-off trench, sand filter and
downstream general rockfill zone.
Evaporation Pond for evaporation of barren water from the hydrometallurgical process and
reverse osmosis plant. The Evaporation Pond is proposed to be fully HDPE lined and
separated into 3 evaporation cells to maximise evaporation potential.
Figure 3-1 shows the general arrangement associated with this FS concept.
Figure 3-1 General arrangement of FS concept plan (ATCW 2019)
GHD identified a number of refinements and opportunities within the existing FS Concept design
arrangement and limitations agreed with Hastings. In particular, the potential to simplify operations and construction including using topography to advantage for more conventional tailings disposal was identified. Low height starter embankments built across existing gullies are
able to cater for the initial years of operation followed by conventional downstream raising of the facilities to expand the facility until end of mine life.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 11
The FS concept design originally proposed Central Thickened Discharge (CTD) for TSF1. This
method of tailings disposal can be very sensitive to thickener performance. A more conventional
tailings dam approach is now proposed that uses perimeter tailings discharge via spigots but
with some CTD components for elevating the tailings beach in a safe manner. While this gives
slightly higher embankment and pipe costs, it eliminates the risks of flatter than expected beach
slopes resulting in insufficient storage capacity during operations.
The concept taken through to Pre-Construction Design as described in this report includes:
1. Combination of TSF 1 and TSF 2 and conversion to a perimeter discharge facility
This change is on the basis of combining the Cleaner 2, 3 and 4 beneficiation tailings with the
Rougher and Cleaner 1 beneficiation tailings. The very fine grained Cleaner 2, 3 and 4 tailings
are expected to be very low density and known to settle poorly unless blended with Rougher
and Cleaner 1 tailings. This means poor beaching, low density and significant water losses in a
separate fines TSF (i.e. TSF 2). Testing is currently underway to confirm the settling
characteristics of the combined beneficiation steam. Recent column settling test work has
returned favourable results indicating suitable decant clarity associated with the combined
tailings (see Section 5.2 for results). This confirms the expected behaviour where the fine
particles are trapped within the overall tailings matrix.
The other consideration at the time of separating the streams was to maintain the higher Total
Activity Concentration (TAC) of radionuclides in Cleaner 2, 3 and 4 tailings within TSF 2. Test
data used by ATCW (ATCW, 2019) showed for separate facilities the Rougher/Cleaner 1
component would have Bq/g of 0.7 and the Cleaner 2, 3 and 4 component Bq/g of 4.0. With
respect to the IAEA guidance on waste classification, both streams may be considered as low-
level NORM waste, suitable for above ground disposal in a tailings facility subject to
satisfactorily meeting appropriate safety requirements (ATCW, 2019). The Cleaner/Rougher 1
tailings which form the majority of the process tailings material have an expected activity
concentration < 1 Bq/g and may effectively be considered as being exempt from classification
as radioactive waste (ATCW, 2019). However, the Cleaner 2, 3 and 4 component is estimated
as comprising only 4% by weight. The combined tailings stream TAC is expected to be
approximately 0.8 Bq/g, still effectively below 1. This 0.8 Bq/g is averaged over the operational
mine life noting that during commissioning, Hastings advise that the TAC is expected to be
about 1.4Bq/g due to the lower initial recovery, resulting in a slightly increased radioactivity level
at start-up.
In addition, the combined beneficiation tailings stream is expected to result in better control of
dust on the combined TSF due to the improved grading, higher moisture level and potential for
crusting. While the tailings are considered benign, dust in general is still considered an
environmental hazard and should be reduced to as low as reasonably practicable. Dust
management is further discussed in Section 6.4.2.
Other benefits of the proposed conventional perimeter discharge in the standalone
Beneficiation TSF include:
Allows the formation of wide beaches upstream of the perimeter embankment that reducesthe risk of seepage and embankment piping. There is less reliance on diversion of surface
water to remove ponding water away from the embankments into the separate ReturnWater Pond as proposed in the original design.
Allows for the development of a decant pond that can be maintained well upstream of the
perimeter embankments, which provides significant stormwater storage capacity with lowrisk of water ponding against the embankments.
Eliminates the need for the Return Water Pond as proposed in the original concept. This
reduces capital cost and environmental risk posed by building a standalone water dam
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 12
alongside the drainage line (i.e. reduced dam failure and seepage risks to the environment).
2. Combining the Hydromet wastes
Combining the Hydromet wastes results in reduced dust risk from the original TSF 3, relying on
transfer of barren liquor from the evaporation pond, and reduces the risk of low density waste
requiring underdrainage. The combined facility allows well proven liner technology using a
combined compacted clay and HDPE liner system (i.e. geocomposite lining system).
Preliminary assessment of the combined waste streams indicates the potential for a small
amount of ammonia gas release at the TSF. Further modelling and assessments provided by
Hastings have confirmed that associated health and safety risks are low and can be managed,
even under worst case scenario conditions (refer Section 9.7).
Figure 3-2 shows the refined concept general arrangement for the basis of the Pre-Construction Design. The following TSF naming convention is used for the Pre-Construction Design presented herein:
Beneficiation TSF: The combined TSF 1 and TSF 2 that receives all Beneficiation tailings
Hydromet TSF: The TSF receiving the combined Hydromet residue, spent liquor and brine
Figure 3-3 shows the respective concept designs overlain for comparative purposes, showing a
reduced overall disturbance footprint for the Pre-Construction Design (FS Concept in red and
Refined Pre-Construction Design in green).
Appendix H includes a summary table highlighting the operational and environmental benefits of
the proposed refined concept design relative to the originally planned FS concept.
Figure 3-2 Proposed pre-construction design concept general arrangement
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 13
Optimisation of the Beneficiation tailings thickening process is still ongoing with the aim of maximising water recovery for plant reuse. At this stage there is no foreseeable basis for the
Beneficiation tailings streams to be separated. In the unlikely event that future plant optimisation demonstrates a significant advantage associated with separating the Cleaner 2 - 4 tailings from the Rougher and Cleaner 1 tailings, this could be achieved by constructing a low height dividing
embankment to create a small separate cell for the Cleaner 2, 3 and 4 tailings (see location Figure 3-2). This would be similar to that proposed in ATCW 2019 but would be contained upstream of broader Beneficiation TSF to avoid creating a separate stand-alone facility (i.e.
reduced risk relative to ATCW 2019).
Figure 3-3 FS concept (red) versus refined pre-construction concept (green)
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4. Basis of DesignThis section defines the Basis of Design (BoD) for the Pre-Construction Design phase of
the two TSFs resulting from development of the FS concept design.
4.1 Design reference documentation
4.1.1 General
A detailed listing of the documents, standards, codes and guidelines to be followed in
the preparation of the Pre-Construction Design are outlined below.
4.1.2 Standards and regulations
Table 4-1 below outlines the standard regulation guidelines that have been used in the
development of the pre-construction design of the alternative arrangement.
Table 4-1 Standard documentation
Organisation Year Title
ANCOLD 1998 Guidelines for Design of Dams for Earthquake
ANCOLD 2000 Guidelines on Selection of Acceptable Flood Capacity for Dams
ANCOLD 2003 Guidelines on Dam Safety Management
ANCOLD 2012 Guidelines on the Consequence Categories for Dams
ANCOLD 2012 Guidelines on Tailings Dams Planning, Design, Construction, Operation and Closure
ANCOLD 2018 Draft Guidelines for Design of Dams and Appurtenant Structures for Earthquake
DME 1998 Guidelines on the Development of Operating Manual for Tailings Storage Facilities
DMP 2010 Managing Naturally occurring Radioactive Material (NORM) in mining and mineral processing, guideline NORM 4.2
DMP 2013 Tailings Storage Facilities in Western Australia – Code of Practice
DMP 2015 Guideline to the Preparation of a Design Report for Tailings Storage Facilities (TSFs)
DMP 2016 Draft Guidance – Materials Characterisation Baseline Data Requirements for Mining Proposals
DMP & EPA 2015 Guidelines for Preparing Mine Closure Plans
DoW 2013 Water Quality Protection Note 27; Liners for Containing Pollutants using Engineered Soils
IAEA 2009 Classification of Radioactive Waste, General Safety Guide
NEPM 1999/2013 Schedule B1; Investigation Levels for Soil and Groundwater
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4.1.3 Hastings documentation
Table 4-2 below outlines the information provided to GHD by Hastings that has been used in
the development of the Pre-Construction Design of the alternative arrangement.
Table 4-2 Hastings provided documentation
Organisation Year Title
Graeme Campbell & Associates Pty Ltd
2017 DFS Study - Stage 1 Hydrogeological Assessment, Yangibana Rare Earths Project, Ref J160014R01.
Radiation Professionals
2016 Baseline Radiation Report, unpublished report for Hastings Technology Metals Limited, November 2016.
Radiation Professionals
2016 Radiation Waste Characterisation Report, unpublished report for Hastings Technology Metals Limited, November 2016.
ANSTO Minerals 2017 Secular Equilibrium and Leach Testing – TSF Solids, Technical Memorandum AM/TM/2017_08_04.
ANSTO Minerals 2017 Pilot Plant Waste Neutralisation and Characterisation, Progress Note 3.
Hastings 2018 Environmental Risk Assessment EnvRisk Ass_MP20170129.
Outotec 2017 Yangibana Flotation Tailings, Rougher, Rougher & Cleaner, Cleaner, Flotation Concentrate, Thickening Test Reports S2786TE.
Trajectory 2017 Landform Evolution Study (R1)
Trajectory 2019 Landform Evolution Assessment
Graeme Campbell & Associates Pty Ltd
2018 Yangibana Rare Earths Project, Tailings Leach Study Report Revision 0.
Landloch 2016 Yangibana Project Soil Assessment, Ref 2274.16A.
ATC Williams 2017 4254-30-RPT-XD-00046 – Geotechnical Investigation.
ATC Williams 2016 4254-30-RPT-XD-00029 Pre-Feasibility Study of Tailings Storage Facility.
ATC Williams 2016 4254-30-RPT-XD-00030 Tailings Storage Facility Options Study.
Hastings 2018 YGB_Tebure_20180626_GDA94z50.
Hastings 2018 Environmental Review Document – Assessment Number 2115 EPBC 2016/7845 Rev 4.
JRHC 2019 Review of ANSTO Results for Samples from Leach Testing of TSF 1 and 2 Samples and Comparison with Groundwater Sampling Results.
Hastings & Groundwater Resource Management
2017 DFS Study – Stage 1 Hydrogeological Assessment.
Hastings & Groundwater Resource Management
2018 Stage 1 Fractured Rock Hydrogeological Assessment.
Resources Health and Safety Services
2016 Radiation Management Plan
Hastings 2019 TSF 2 Seepage Model – Results.
Hastings 2019 P058 Yangibana Plot Plan.
ERM 2019 Screening level air quality assessment of Ammonia emissions from the Hydromet TSF Ref:0504573
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 16
4.2 Basis of design parameters
The Basis of Design (BoD) is presented below in Table 4-3, including sources and assumptions.
The pre-construction design has been completed based on information provided to GHD by
Hastings, including feasibility level process design, waste classification, water balance and
limited geotechnical knowledge available at the time of this report issue. During investigations,
construction and operation, it is essential to monitor these conditions, verify assumptions made
in the design and then refine designs as actual data is available over time. This will allow
designs to be optimised over time, as further information becomes available and the design and
construction methodologies evolve.
Instrumentation data reviews are essential to identify trends in the data that may require design
changes. It is necessary to take proactive steps well before the integrity of the structures and /
or the operations are impacted. Addressing issues at a later stage may be operationally difficult,
expensive and could be impractical.
Table 4-3 Basis of design parameters
Design Aspect Design Basis Design Source
Storage
Life of Mine 10 Years Feasibility Design Report
Total LOM Tailings Volume ~ 7.5 Mm3 GHD Assessed
Climate
Average Monthly Rainfall 18.9 mm Feasibility Design Report Average Monthly Evaporation 264.9 mm
Annual Tailings Production
Beneficiation Plant Rougher + Cleaner 1 Tailings
927,000 t Hastings
Beneficiation Plant Cleaners 2, 3, 4 Tailing
47,500 t
Hydromet Plant Tailings 72,000 t
Estimated LoM Tailings Production Solids
Beneficiation Plant Rougher + Cleaner 1 Tailings
9.27 Mt Hastings
Beneficiation Plant Cleaners 2, 3, 4 Tailing
0.475 Mt
Hydromet Plant Tailings 0.72 Mt
Barren Water Effluent Production
Hourly Production 58 t/m3
Annual Production 457,000 m3
Project Restrictions
Waterway exclusion zone 50 m (Minimum) Kick Off Meeting Minutes Location Within FS concept general
arrangement footprint
Radiation Risk based management
Groundwater Minimise impact
Dust Risk based management
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Water Re-Use Beneficiation tailings water suitable for reuse Hydromet water and RO brine not suitable for re-use
Table 4-4 TSF design characteristics
Design Aspect Design Basis Design Source
Beneficiation TSF
Waste Types Stored All Beneficiation Plant Tailings Hastings
Decant Water Reuse Suitable for Plant Reuse
Embankment Crest Width 7 m GHD Assessed
Embankment Trafficable Width 4 m (minimum)
Embankment Upstream Slope 2H : 1V
Embankment Downstream Slope 2.5H : 1V
Tailings Beach Slope (based on 49% solids)
1% Assumed
Tailings Deposition Method Perimeter discharge with spigots at nominal 50 m spacing
GHD Assessed
Starter Dam Capacity 3 Years
Decant Arrangement Central Pond and Decant Tower
Construction Material Mine waste and available onsite materials
Hydromet TSF
Waste Types Stored Hydromet Tailings and Barren Water (combined)
Hastings
Decant Water Reuse Not Suitable for Plant Reuse
Crest Width 7 m GHD Assessed
Trafficable Width 4 m (minimum)
Upstream Slope 3H : 1V
Downstream Slope 2.5H : 1V
Tailings Beach Slope 0 - 0.25% Assumed GHD Assessed Tailings Deposition Method Single Point Discharge
Starter Dam Capacity 3 Years
Lining Requirement Geocomposite liner 300 mm CCL plus Geosynthetic Liner (1.5 – 2.0 mm HDPE)
Decant Arrangement No water return to plant
Construction Material Mine waste and available onsite materials
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5. Tailings characterisation5.1 Tailings testing
5.1.1 Previous testing
A summary of the previous analysis performed on the pilot tailings is presented in Table 5-1.
Table 5-1 Previous testing summary
Date Source Material Analysis
2016 Radpro Baseline monitoring and beneficiation plant tailings (solid & liquid) and hydromet plant residue (solid)
Radiation - activity concentration and exposure classification
2016- 2017
ATCW Beneficiation plant tailings and hydromet plant residue
Physical and geochemical properties
2016- 2017
JRHC Beneficiation plant tailings and hydromet plant tailings (solids & liquids)
Radiation characterisation
2017 Outotec Beneficiation plant tailings and hydromet plant tailings
Plant thickener evaluation test work
2017 ANSTO Minerals
Beneficiation plant tailings and hydromet pilot plant tailings (solids & liquids)
Elemental assays (XRF), radionuclide analysis & ASLP (leachate testing at acidic (pH 5) and alkaline (pH 9.2) conditions)
2017 Trajectory GCA
Beneficiation plant tailing and hydromet plant tailings (solids & liquids)
Geochemical characterisation
2018 Trajectory GCA
Beneficiation plant tailing and hydromet plant tailings (solids & leachate)
Column leach tests with groundwater and high-purity deionised-water
5.1.2 2019 Supplementary testing of combined beneficiation tailings
As discussed in Section 3, design development resulted in a decision to combine all Beneficiation tailings into a single TSF (the “Beneficiation TSF”).
The testing as described above included testing of the Beneficiation rougher and Cleaner 1
tailings as well as Beneficiation Cleaner 2 – 4 tailings. Testing on samples of combined Beneficiation tailings had not been carried out. While the combined tailings properties can be inferred from the results of the testing on the individual tailings streams, it was considered
prudent that further testing be carried out to provide additional data relating to the physical and geochemical properties of the combined Beneficiation tailings.
In March 2019, a suite of physical and geochemical tests commenced at GHD and ALS
Laboratories respectively with the results to be used to further inform detailed design. Results are discussed in the sections that follow.
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5.2 Physical properties
5.2.1 General
The results of the testing for the tailings physical characterisation test program are summarised
in Table 5-2, taken from Table 2 of ATC Williams FS Concept Design Report and including available results from the 2019 supplementary testing. The supplementary testing results are included as Appendix B.
Table 5-2 Testing physical characterisation test results
Test Item Unit Beneficiation Rougher + C1
Pilot Plant
Beneficiation (C2 – C4)
Pilot Plant
Combined Beneficiation Tailings (Pilot
Plant)
Hydromet Pilot Plant
Design Stream Beneficiation TSF Hydromet TSF
Source ATCW 2019 ATCW 2019 GHD 2019 ATCW 2019
D100 µm 150 75 300 66
D80 µm 80 10 90 27
<0.075 mm % 77.3 99.7 72 100
SG g/cm3 3.30 3.22 3.12 3.16
Liquid Limit % 21 39 24 113
Plastic Limit % 18 23 21 68
Plasticity Index % 3 16 3 45
Decant pH pH 9.8 10 - 6.5
Permeability (50 kPa)
m/sec 5.0 x 10-09 3.8 x 10-08 2.0 x 10-09 6.0 x 10-08
Solids Content Cw
% 49 20 40 51.7
51.7 Slurry EC µs/cm - - - 10,380
Decant EC µs/cm 2,130 - - -
Decant TSS mg/L 88
Segregation Threshold
% 39 13 - -
Initial Settled Density (D)
t/m3 1.13 0.51 - 0.48-0.52
Initial Settled Density (UD)
t/m3 1.42 - 0.83 -
Bleed Water m3/t 0.5 1.5 - 0.283
% 44 39 - 14.4
Shrinkage Limit Density
t/m3 1.71 0.92
Yield Stress Pa 3 - - 34
Plastic Viscosity mPa.s 19 - - 84
5.2.2 Beneficiation plant tailings
The testing undertaken by ATCW indicates that the beneficiation plant (Rougher + Cleaner 1)
tailings, are low plasticity sandy silt with maximum grain size of 0.15 mm. The second half of the beneficiation process known as the Cleaner 2 to Cleaner 4 tailings comprise medium plasticity
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 20
clay with approximately 40% clay content (< 2 μm). These finer tailings are reported to have
poor settling properties unless blended. Details on the thickener test work, expected solids
concentration, decant clarity and further assessment of the behaviour for these separated
streams can be found in ATCW 2019.
The Beneficiation TSF is now designed to accommodate the combined Rougher + Cleaner 1
and Cleaner 2 to Cleaner 4 tailings via a single thickener and tailings delivery pipeline.
The testing undertaken by GHD concurs with results expected from previous testing, indicating
that the combined beneficiation plant tailings settle out effectively providing a decant quality
suitable for plant reuse. Further geotechnical testing is ongoing to inform detailed design
including additional column testing at the higher solids content expected from thickening to
confirm the assumed settled and dried densities.
Table 5-3 presents the physical characteristics adopted for the purpose of the pre-construction
design.
Table 5-3 Beneficiation tailings assumed physical properties
Design Aspect Design Basis
Pumped Solids Content 52% (see Note 1)
Initial Settled Density 1.1 t/m3
In situ Beach Density 1.5 t/m3
Specific Gravity 3.30 g/cm3
Decant Total Suspended Solids <100 mg/l
Note 1 – Tailings solids content to be between 50% - 55% as advised by Hastings 28th March 2019 based on
thickening test work.
5.2.3 Hydromet tailings
The tailings produced from the Hydromet plant will be in the form of a precipitated residue
comprising approximately 6% of the total process tailings. Additional effluent produced by gas
scrubbing will consist of gypsum residue which forms about 1.2% of the total process tailings.
The combined residue sample assessed by ATCW was considered to comprise a soft, black silt,
with approximately 15% clay fraction. Atterberg limits undertaken by ATCW indicated the
material to have very high plasticity. The material was in the form of a cake at an as received
solids content of approximately 52%. Dilution of the sample to 33% solids content with
neutralisation residue re-leach liquor was undertaken to produce a thickened self-levelling
slurry.
Table 5-4 below presents the hydromet tailings physical characteristics adopted for the purpose
of pre-construction design.
Table 5-4 Hydromet tailings assumed physical properties
Design Aspect Design Basis
Pumped Solids Content 11%
In situ Tailings Density 0.5 t/m3
Specific Gravity 3.16 g/cm3
The Hydromet TSF is designed to accommodate the combined tailings, barren water and brine
effluent. At this stage it is intended that the tailings and effluent would be combined and
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 21
deposited via a single common pipeline. Despite the low solids content at the time of deposition, the assumed final settled tailings density of 0.5 t/m3 is still considered to be suitably
conservative for the purpose of preliminary sizing of the facility. In practice it is likely that evaporation will lead to additional densification of the hydromet tailings with a potential to result in higher than assumed final densities.
5.3 Geochemical characterisation
5.3.1 Beneficiation plant tailings
Previous analysis
Tailings solids (TSF 1 and TSF 2)
Previous analysis (ATCW and Graeme Campbell and Associates (GCA)) found tailings to be benign geochemically and non-acid forming (NAF) (ATCW, 2019). However, ANSTO analysis
found that there are enriched concentrations of most metals, in particular Al, Fe and Mn, which reflect that of the ironstone orebody from which they were derived (ATCW, 2019). Tailings solids in Cleaner 2 – Cleaner 4 streams (previously reporting to TSF 2) were enriched in rare earth
elements (REE) and lead associated with the ore body but exist as fixed forms only (ATCW 2019).
Tailings pore water (TSF 1 and TSF 2)
Results for preliminary analysis of the pore water from all tailings streams was alkaline
(pH 10 - 11) compared to a near neutral groundwater pH of 8; and was brackish with a salinity ranging from 1450 mg/l to 2080 mg/l, which is within the same salinity range as the local groundwater (ATCW, 2019). TDS and most metal concentrations in the pore water and
groundwater were comparable. However, the pore water had lower concentrations of Ca and Mg and higher concentrations of As, F, Mo and Si compared to the groundwater. Trajectory and GCA (2017) found that F and Mo were elevated above ANZECC Livestock Drinking Water
Guidelines. ATCW (2019) suggests “the presence of soluble F forms may reflect the small
amounts of fluorites, fluorine bearing micas and/or fluoro-phosphates in the Yangibana ore. The soluble Mo forms may be present as molybdate associated with the phosphates.”.
Samples of tailings solids were subjected to ASLP testing by ANSTO (2017), using both acidic (pH = 5) and alkaline (pH = 9.2) leaching fluids. A detailed analysis of these results is documented in the ATCW FS Preliminary Concept Design Report (ATCW, 2019). The results
showed that, for most elements, there was no significant leaching of any element (< 100 mg/L) or radionuclide from any of the three TSF solids using the acidic or alkaline leach testing fluids. Uranium-238 (0.02 mg/L; 0.25 Bq/L) was found in both the acetate and borate leachates for the
rougher 1 (TSF 1) and cleaner tails (TSF 2) leachates. The acetate and borate leachates extracted 1.9 and 1.3 %, respectively of U-238. The highest concentration of any radionuclide was 0.81 Bq/L for Ra-228 in the acetate leachate for the cleaner tails. ANSTO (2017) concludes
“the concentrations of all measured radionuclides, however, are not considered to be significant”.
Additional leaching and weathering testwork were conducted by Trajectory and GCA (2018) to
assess the solubility behaviour of TSF 1 and 2 solids samples using groundwater obtained from fractured rock and palaeochannel aquifers at the Yangibana Rare Earths Project site and high purity deionised water, as well as humidity cell testing. For TSF 1, approximately 6-7 pore
volumes were passed through the test columns over a period of 15 weeks. The results of the leach study for TSF 1 tailings solids showed that, upon leaching with either High Pressure Deionised Water (HPDW) or locally acquired groundwater under saturated conditions, soluble-F
and soluble-Mo concentrations rapidly decreased and thus confirmed that the recorded soluble-
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F and soluble-Mo elevations were mainly associated with tailings process water, and thus would diminish with flushing. For TSF 2, approximately 2-3 pore volumes were passed through test
columns over a period of 15 weeks. The leachate-F and leachate-Mo concentrations trended downwards with similar outcomes to the TSF 1 leach tests but much more slowly due to the nature of the tailings. In summary, this concludes that elevated F and Mo concentrations are not
a long term feature of the tailings leachate (Trajectory and GCA, 2018).
Summary
Table 5-5 summarises the geochemical analysis of TSF 1 and 2 tailings.
Table 5-5 TSF 1 and 2 geochemical analysis summary
Characterisation TSF 1 TSF 2
Solids Liquids Solids Liquids
AMD testing (ATCW, 2019; Trajectory and GCA. 2017)
NAF Circum Neutral/Saline
NAF Circum Neutral/Saline
Suite of multi- elements (ANSTO, 2017; Trajectory and GCA, 2017)
No significant elevations but enriched in Al, Fe and Mn
Elevated F and Mo
No significant elevations but enriched in REE and Pb
Elevated F and Mo
Physical characteristics (ATCW, 2019; Trajectory and GCA, 2017)
Sodic N/A Sodic N/A
Fibrous materials testing (Trajectory and GCA 2017)
None detected N/A None detected N/A
Radionuclide concentrations (ANSTO, 2017)
0.7 Bq/g Not significant; below detection limits
4 Bq/g Not significant; below detection limits
pH 10-11 10-11 10-11 10-11
GHD 2019 supplementary testing
As mentioned in Section 5.1.2, further testing on the combined geochemical characteristics of the Beneficiation TSF has been conducted. Table 5-6 summarises the analysis performed.
Table 5-6 Summary of geochemical test work
Parameter Tailings Solid Pore Water LEAF leach testwork
Net Acid Production Potential (NAPP) X
Net Acid Generation (NAG) X
Kinetic Net Acid Generation (KNAG) X
Acid Buffering Characteristic Curve (ABCC)
X
Total Metals by inductively coupled plasma mass spectrometry (ICPMS) Full Suite
X (mg/kg) X (mg/L) X (mg/L)
Total Mercury X (mg/kg) X (mg/L) X (mg/L)
pH and EC (1:5) (µs/cm and pH Unit)
X X
General Water Suite (mg/L) X
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Parameter Tailings Solid Pore Water LEAF leach testwork
Suspended solids (mg/L) X
Combined tailings solids (Beneficiation TSF)
Geochemical Abundance Index
To gain an early understanding of the risk a particular metal may pose to the environment, a comparison between the total metal concentrations (by ICPMS) and their average crustal abundance can be presented as a Geochemical Abundance Index (GAI). This is only a simple,
preliminary method of assessment, as it does not take into account the solubility and mobility of the metals nor their relative toxicity to the receiving environment. A GAI of less than 0 indicates that the content of the element is less than the average crustal abundance. A GAI of 3
corresponds to a 12-fold enrichment above the average-crustal-abundance; and so forth, up to a GAI of 6 which corresponds to a 96-fold, or greater, enrichment above average-crustal abundances. A GAI of 3 or greater is considered significantly elevated (DFAT, 2016).
GAIs were calculated for 28 metals (Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, S, Sb, Se, Sn, Sr, Th, Tl, U, V, Zn, Table 5-7), of these 3 (Pb, Se and Th) returned GAIs greater than 3, indicating relatively enriched concentrations. Lead and thorium reported
GAIs slightly above 3 at 3.7 and 3.3 respectively while selenium reported at 7.6.
These outcomes are consistent with previous findings although further analysis will confirm whether or not the REE and Al, Mn and Fe are also elevated.
The high selenium concentrations may be an artefact of spectral interferences during inductively coupled plasma mass spectrometry (ICPMS), because the argon gas used during analysis can provide significant overlaps on all selenium isotopes (Paul, 2016). ALS uses Se78 for ICPMS
analysis, which is known to have interference from krypton (a contaminant of the argon used in ICPMS; Paul, 2016). In addition, Se is below detection limit in the leached samples at a range of pH conditions (see Table 5-8 and Table 5-9) indicating that it is immobile. As a result of low
leached concentrations and known interference of this element during ICPMS it is concluded that high concentrations of selenium reported are an artefact of the analytical process.
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Table 5-7 Summary of total metal (ICPMS) concentration and GAI values*
Metals Concentration (mg/kg) GAI Value
Ag 0.7 2.7
Al 3920 -5.1
As 7.8 1.5
B <50 0.7
Ba 1020 0.6
Be 3.4 -0.5
Bi 0.3 0.2
Cd 0.2 -0.7
Co 12.8 -1.6
Cr 58.5 -1.4
Cu 25 -1.8
Fe 43600 -2.9
Hg <0.1 -1.3
Li 17.7 -0.8
Mn 3210 1.1
Mo 4.7 1
Ni 33.4 -1.8
Pb 255 3.6
S <0.01 (%) -3.5
Sb <0.1 -2.7
Se 16 7.6
Sn 3.4 -1.5
Sr 58.1 -3.4
Th 153 3.3
Tl 0.8 0.2
U 8.4 1
V 20 -3.4
Zn 86.6 -0.4
*sourced from lab report ES1907149 Appendix C.
Acid Base Accounting
To provide additional assessment, the sample underwent AMD tests, comprising net acid
generation (NAG), net acid production potential (NAPP - comprising total sulfur and acid
neutralising capacity), kinetic net acid generation (KNAG) and acid buffering characteristic curve
(ABCC) tests (AMIRA 2002). The results are consistent with previous findings.
Total sulfur and Maximum Potential Acidity (MPA)
The total sulfur reported at below detection limit (<0.01 %). The sample returned an MPA value
of 0.15 kg H2SO4/t, determined using half the detection limit of sulfide. An MPA greater than
10 kg H2SO4/t is typically considered to represent a significant AMD risk if there is no
neutralising capacity (Table 5, DITR, 2016).
Acid Neutralising Capacity (ANC)
The sample reported a titrated ANC value of 7.3 kg H2SO4/t. This indicates that the material has
some limited neutralising capacity.
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Net Acid Producing Potential (NAPP)
The NAPP, determined using half the detection limit of sulfide, was -7.1 kg H2SO4/t.
Consequently, the sample may be classified as non-acid-forming (NAF) using NAPP results
only.
Neutralising Potential Ratio (NPR)
The NPR, determined using half the detection limit of sulfide, reported at 47.7, which is
significantly larger than the AMIRA (2002) guide of a minimum NPR of 2.0 as a factor of safety
for self-neutralising material.
Net Acid Generation (NAG)
Net Acid Generation (NAG) results were in agreement with the NAPP results and showed a very
low risk of acid generation. The oxidation values was 8.9, above 4.5, the value considered as
acidic (AMIRA, 2002). The initial pH value was also highly alkaline with a pH of 10.1.
Kinetic Net Acid Generation (KNAG)
The kinetic NAG (KNAG) test returned a final pH value (9.08) that was reflective of the NAG test
(8.9). At no point during the test did the pH decrease and thus did not reach a pH of 4.5, the
value considered as acidic (AMIRA, 2002).
The sample reported a pH increase throughout the test, though it is most noticeable at
approximately 150 minutes, this is paired with the peak temperature for the test, reaching
74.6°C. This indicates the presence of slow reacting neutralising potential.
Acid Buffering Characteristic Curves (ABCC)
The acid buffering characteristic curves (ABCC) test involves the slow titration of a sample with
acid while continuously monitoring pH. These data provide an indication of the portion of ANC
within a sample that is readily available for acid neutralisation. The titrated ABCC value at pH
4.5 (3.9 kg H2SO4/t), is lower than the initial static ANC values (7.3 kg H2SO4/t). The ABCC
derived acid neutralising capacity shows that the static ANC values have, overestimated the
acid neutralising capacity of the samples, however even with the reduced ANC the sample still
classifies as NAF.
LEAF Test method 1313
Additional leach testing of the combined beneficiation tailings was undertaken to further
understand the differences in the leach behaviour. The Leaching Environmental Assessment
Framework (LEAF Procedure) test method 1313 was performed, which determines how
liquid- solid partitioning varies with the pH of the leaching solution using a parallel batch
extraction procedure (DER, 2015). Results of nine pH conditions were produced (13, 12,
10.5, 9, 8, 7, 5.5, 4 and 2). The available pH conditions cover both the extreme range for
LEAF leaching 2 -13 and provide details on pH levels closer to site conditions (12 and 10.5).
LEAF testing is recommended by EPA Western Australia (DER, 2015) and has been
requested by DWER.
The following is a brief summary of the LEAF method 1313 from US-EPA (2017):
“This method consists of nine parallel extractions of a particle-size-reduced solid material
in dilute acid or base and reagent water. A schedule of acid and base additions is
formulated from a pre-test titration curve or prior knowledge indicating the required
equivalents/g acid or base to be added to the series of extraction vessels so as to yield a
series of eluates having specified pH values in the range of 2-13. In addition to the nine
test extractions, three method blanks without solid samples are carried through the
procedure in order to verify that analyte interferences are not introduced as a
consequence of reagent impurities or equipment contamination. The 12 bottles (i.e., nine
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test positions and three method blanks) are tumbled in an end-over-end fashion for a specified contact time, which depends on the particle size of the sample. At the end of the specified contact interval, the liquid and solid phases are roughly separated via
settling or centrifugation. Extract pH and specific conductivity measurements are then made on an aliquot of the liquid phase and the remaining bulk of the eluate is clarified by either pressure or vacuum filtration. Analytical samples of the filtered eluate are collected and preserved as appropriate for the desired chemical analyses. The eluate concentrations of constituents of potential concern (COPCs) are determined and reported. In addition, COPC concentrations may be plotted as a function of eluate pH
and compared to QC and assessment limits for the interpretation of method results.”
Given the leaching procedure’s relatively aggressive nature (similar to the ASLP test with a prolonged period of agitation which encourages reactivity) and the potential for dilution in the environment, a dilution factor of 10 can be applied to the LEAF results when considering their environmental significance (WADEC, 2009).
Western Australia has developed unlined landfill acceptance criteria (WADEC, 2009) for Class I and Class II materials, which includes inert materials and clean fill. These guidelines are based on the 2011 Australian drinking water guidelines (ADWG) multiplied by a factor of
10. As inert landfill materials and clean fills use a factor of 10 when compared to guidelines
it is appropriate for the conservative LEAF leach results to use a dilution factor of 10.
Results can otherwise be interpreted as exaggerated and should therefore be understood with the nature of the testing in mind, i.e. to flag the risk of metalliferous drainage being
generated from the samples.
The LEAF tests results were assessed against the ANZECC and ARMCANZ (2000) stock watering guidelines and the NEPM (2013) groundwater investigation levels
(GILS).
ANZECC and ARMCANZ Livestock guidelines
The plant filtrate has a pH of 11.8, which is most similar to the LEAF test T02 (pH 12). The results from T02 reported no exceedances of the guidelines at the leach pH of 12 indicating that
conditions in the combined beneficiation pore water will be below the ANZECC and ARMCANZ (2000) livestock guidelines (Table 5-8).
Results for T01 (pH 13) and T03 (pH 10.5) represent the next closest alkaline and acidic
conditions to the current conditions of pH 11.8. These leaches do have exceedances for Al, and Mo for T01 (15.7 mg/L and 0.064 mg/L) and Mn for T03 (2.35 mg/L). The exceedances are still less than 10 times the livestock guidelines, which considering the aggressive nature of the
leaching further demonstrates the benign nature of these tailings under this pH range.
The LEAF test T09 (pH 2) showed the greatest exceedances (Al, Mn, Se and U), however these extremely acidic conditions are highly unlikely to occur within the beneficiation tailings or in
surrounding groundwater (average pH 8.02; ATCW, 2019).
Figure 5-1 shows the concentration changes of analytes at different pH levels. The majority of metals have higher concentrations under acidic conditions, hyper alkaline pHs of 12 and 14
show the lowest concentrations for Cd, Co, Cu, Mn, Ni, Se and Zn. Aluminium, As, U and Cr are amphoteric with the lowest concentration at neutral pH. Molybdenum, reports an increasing concentration with increasing pH. Mercury is at detection limit across the range of pH
conditions. This suggests that an alkaline pH results in lower concentrations for most metals.
Calcium and Mg report at detection limit (<1 mg/L) for the majority of leaches and blanks. Ca and Mg report values at leaches T06 and T09 (pH 7 and 2, respectively) though these are low
and don’t exceed the livestock guidelines for Ca or Mg.
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NEPM Groundwater Investigation Levels
The T02 leach (pH of 12) analysis shows exceedances of the NEPM freshwater guideline
values for three analytes (Cr, Cu and Ag) but has no exceedances for the NEPM drinking water guidelines (Table 5-9). Of those three exceedances, Ag is reporting at detection limit (<0.001 mg/L), which is higher than the guideline value (0.00005 mg/L). Given Ag reports at detection
limit in all leaches this should be treated as a quality issue and is of low risk. Copper reports at 0.002 mg/L, which is lower than the blank leach B03 (pH 13) at 0.005 mg/L indicating the exceedance is likely caused by the reagents or equipment. Chromium is reporting at the
guideline value 0.001 mg/L, which is also the detection limit value. Thus the metal concentrations at T02 leach conditions are considered low risk. In summary, when taking quality control, reagent and equipment contamination issues into account, the T02 leach results show it
is benign in nature and unlikely to pose any risk to the environment.
Results for T01 and T03 (pH 13 and 10.5) show exceedance but all are less than ten times the guidelines with some exceedances being caused by reagent and equipment contamination (i.e.
Cu, Pb and Zn).
Figure 5-1 Metal concentration at varying LEAF pH conditions
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Table 5-8 LEAF leach and pore water compared to ANZECC and ARMCANZ livestock guidelines (2000)
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Table 5-9 LEAF leach and pore water compared to NEPM drinking water and fresh water guidelines (2013)
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QA/QC method blanks and effects of the reagents
Three method blanks without the beneficiation solids (B01 pH 7, B02 pH 2 and B03 pH 13) were
also ran with the LEAF leach tests to determine if reagent or equipment contamination has caused any of the resulting analyte concentrations. Analytes Al, Cu, Mn, Mo, and Zn had concentrations above the detection limit in the blank samples indicating a low level of
contamination. Some of these also exceeded the NEPM guidelines (B03 Al at 0.17 mg/L and Cu at 0.005 mg/L).
There are higher levels of Na and K reported at the higher pH leaches (13 and 12) caused by
the use of potassium hydroxide (KOH) or sodium hydroxide (NaOH), i.e. due to it being the base used to achieve higher pH leaches.
Combined pore water (Beneficiation TSF)
Plant filtrate results
The plant filtrate results were assessed against the ANZECC and ARMCANZ (2000) stock watering guidelines and the NEPM (2013) groundwater investigation levels (GILS), where applicable (Table 5-8 and Table 5-9).
The plant filtrate results reflect the current conditions expected in the combined beneficiation liquid. The filtrate reported a pH of 11.8 and an EC of 5220 µs/cm. The livestock and NEPM guidelines do not have values for EC but values at that level are still considered suitable for long
term irrigation (100 years) of specific crops (barley, wheat, cotton safflower, sorghum; ANZECC and ARMCANZ, 2000).
Chloride reports at 285 mg/L, which also has no livestock or NEPM guidelines. It is, however,
within the range for long term irrigation of moderately tolerant to tolerant crops (ANZECC and ARMCANZ, 2000). Sulfate concentration is reported for the plant filtrate at 182 mg/L which does not exceed the livestock or NEPM guidelines (1000 and 500 mg/L).
Fluorine concentrations (2.6 mg/L) exceeded the livestock guidelines (2 mg/L) and the NEPM drinking water guideline (1.5 mg/L), though once environmental dilution factors are considered this is not significant. Previous testing found that fluorine concentrations diminished with flushing
and were not a long term effect (Trajectory and GCA, 2018)
Total dissolved solids reported at 3390 mg/L, which is below the upper range for livestock (5000 mg/L). Alkalinity tests by PC titrator found the majority came from hydroxide at 703 mg/L
followed by Carbonate at 213 mg/L with bicarbonate concentrations at detection limit.
Recycled process water
The plant filtrate tests characterise the initial conditions onsite, it does not identify whether repeated recycling of process water would increase concentrations of key elements Mo and F. A
review of the recycled process water quality has been undertaken by Hastings to determine if the predicted decrease in Mo and F concentrations due to flushing would be impacted by recycling. The full report and results from this review can be found in Appendix C.
Locked cycle test work ran for a total of 15 cycles with Mo and F recorded in the final 3 cycles. The concentrations for F were greater than in the plant filtrate tests with a final value of 4 mg/L compared to 2.6 mg/L. Fluorine concentrations exceed the livestock guidelines (2 mg/L) and the
NEPM drinking water guideline (1.5 mg/L). The final three cycles show similar concentrations in F suggesting stabilisation in F concentrations.
The final Mo concentration reported at 2.5 mg/L, which exceeds both the livestock and NEPM
drinking water guideline (0.05 mg/L). Molybdenum also appears to stabilise with the final three cycles showing no significant increasing trends.
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The test was designed under locked cycle conditions, however the current water modelling for the site indicates that in steady state the process will operate on a mix of 80:20 recycled water
to fresh raw water. This is expected to produce lower concentrations of Mo and F due to the addition of the fresh raw water.
There were other minor exceedances for Cd, Cr, Cu, Al, Ag, Pb, Zn and Ni, though most of
these were caused by detection limits exceeding the guideline limit (Cd, Cr, Pb, Ni and Ag). Previous testing performed by ATCW and GCA (2018) did not highlight these metals as significant in the decant water.
Summary
In conclusion, an additional complement of geochemical testing has been conducted on a combined beneficiation tailings sample, representative of the tailings stream reporting to the Beneficiation TSF. The additional tests confirm previous findings and verify the characterisation
of the combined beneficiation tailings streams:
The beneficiation TSF solids report below a GAI of 3 for the majority of metals, except for
Pb and Th, though these are shown to have low concentrations (not exceeding the
guidelines or at detection limit) in the T02 leach liquid indicating that the metals are not
mobile at current pH conditions.
The solids can be classified as NAF with alkaline pH and saline EC concentrations.
Leaf leach T02 (closest pH conditions to pore water 11.8 pH) had no significant
concentrations of analytes compared to the ANZECC and ARMCANZ livestock guidelines
(2000) and the NEPM fresh water and drinking water guidelines (2013).
Plant filtrate initially and recycled had no significant concentrations of analytes compared to
ANZECC and ARMCANZ livestock guidelines (2000) and the NEPM fresh water and
drinking water guidelines (2013) except for fluorine and molybdenum. Minor exceedances
in Al, Cu and Zn were observed. Potential management solutions are recommended in
Section 6.4.3.
Table 5-10 summarises the geochemical characteristics of the solids and liquids reporting to the
Beneficiation TSF. This aligns with the previous TSF 1 and 2 geochemical characterisation as expected.
Table 5-10 Summary of Beneficiation TSF characterisation*
Characterisation Beneficiation TSF
Characterisation Solids Liquids
AMD testing NAF Alkaline/Saline
Suite of multi-elements No significant elevations Elevated F and Mo
Physical characteristics Sodic N/A
Radionuclide concentrations 0.8 Bq/g Not significant; below detection limits
pH 10.1 11.8
*Summary based on geochemical lab results Appendix C.
5.3.2 Hydromet plant tailings
Previous analysis
TSF 3 solids (Plant Residue and Scrubbing Effluent)
Testing by ANSTO confirmed that hydromet tailings were also NAF (ATCW, 2019). Elemental assays on the TSF 3 tailings, comprised of hydrometallurgy plant tailings and scrubbing effluent,
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indicated relative enrichment (compared to the beneficiation plant tailings) in Ba, Cr, Ni, Pb, Th, U, Ca, P and S and relative depletion was evident in Al, Cu, Mn, V, Zn, Fe, K, Si and Ti. The
material is circum neutral (pH 6.6) and radionuclide concentrations are 32.4 Bq/g (ANSTO, 2017). No solids reported to the evaporation pond.
TSF 3 and evaporation pond liquor
The tailings pore water from the hydrometallurgy process, reporting to TSF 3, is circum neutral
(pH 6.6). The pore water contains levels of Mg, and SO4 which are several times in excess of the ANZECC Livestock Water Quality Guideline (Trajectory and GCA 2017). TDS is higher than background groundwater at 12,000 mg/L compared to between 1400 mg/L and 2800 mg/L. The
residue is lower in Na, Si, Cl-, F-, NO3-, higher in Ca and Mn and of similar concentrations in Al and B compared to groundwater.
The barren liquor reporting to the evaporation pond is neutral (pH 7) and is expected to be
largely magnesium sulfate and ammonium sulfate solution with elevated concentrations of NH4, Mg, S and SO4 compared to groundwater (R Zhang, 2019, personal communication; ATCW, 2019). Ammonium bicarbonate is used to precipitate REEs from solution, after precipitation
nearly all NH4 reports to the evaporation pond liquor at concentrations estimated at 18g/L (R Zhang, 2019, personal communication).
The liquor is lower in Na, higher in Ca, Mn and F and of similar concentrations in Si compared to
groundwater. Due to the neutralisation of the residue, the pH will be 7 compared to a background groundwater pH of 8.
ASLP testing was also undertaken on TSF 3 solids as per that described in Section 5.3.1 for the
tailings pore water (TSF 1 and 2; ANSTO, 2017) and resulted in the same outcomes: Low concentrations of radionuclides (not considered significant by ANSTO, 2017) and no significant leaching of any element (ANSTO 2017).
Summary
Table 5-11 summarises the geochemical analysis outcomes of solids and liquids reporting to the evaporation pond and TSF 3.
Table 5-11 Evaporation pond and TSF 3 geochemical analysis summary*
Characterisation Evaporation pond TSF 3
Solids Liquids Solids Liquids
pH and TDS N/A Circum Neutral/Saline NAF Circum Neutral/Saline
Suite of multi- elements/Salts
N/A Elevated Mg, Mo, S, F, NH4 and Co
No significant elevations
Elevated Mg, SO4, S and Mo
Physical Characteristic N/A Will evaporate to a salt Sodic N/A
Fibrous materials testing N/A N/A None detected N/A
Radionuclides N/A None Detected 32.4 Bq/g None detected
pH N/A 7 6.6 6.6
*Summary based on geochemical lab results, Appendix C, ATC Williams (2019) and ANSTO
(2017).GHD 2019 analysis
GHD 2019 analysis
Solids (Hydromet TSF)
The solids component does not vary from that of the previous TSF 3 solids. As a result, no
further assessment of the Hydromet TSF solids has been undertaken and will be consistent with that previously determined (as described in Section 5.3.2 TSF 3 solids above).
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Combined liquor (Hydromet TSF)
Previous analysis of the TSF 3 and evaporation pond liquors were used to determine the
combined Hydromet TSF liquor mass balance, which was used to predict concentrations of key analytes (i.e. F, Mo, Mg, NH4, SO4, U and Th) known to be elevated in this facility. The mass balance is based on the assumption that little to no reactivity will occur and is only an indication
of possible characterisation.
However, it should be noted that ammonia gas may be produced in small quantities due to the reaction between caustic soda from the gas scrubber waste and ammonium sulfate from the
evaporation pond liquor. Hastings commissioned an air emissions study (ERM, 2019, Appendix
I) that involved dispersion modelling based on estimates of ammonia gas evolution under “worst
case conditions”. This confirmed low risk of both onsite and offsite exceedances as discussed in
Section 9.7.
The mass balance (Table 5-12) shows that the concentrations of key analytes in the evaporation pond liquor have been diluted slightly by combining the two facilities (TSF 3 and
evaporation pond) into the Hydromet TSF.
Verification of the geochemistry of the TSF 3 pore water will be completed upon operations of the TSF. Regardless, the use of liners and underdrainage to encapsulate these tailings provides
contingency if there is variation in our current understanding of the geochemistry.
Table 5-12 summarises the original mass and concentrations of the separate liquors and the potential concentrations when combined.
Table 5-12 Mass balance of Hydromet TSF*
Source Mass (t) F (mg/L) Mo (mg/L)
Mg (mg/L)
SO4
(mg/L)
U
(mg/L)
Th (mg/L)
TSF 3 liquor 114,155 0.5 0.5 3,050 15,900 0.5 0.5
Evaporation pond liquor
434,500 5 0.5 6,721 30,000** 0.5 0.5
Combined Hydromet TSF liquor
548,655 4.1 0.5 5,957.2 27,066.3 0.5 0.5
*TSF 3 liquor and evaporation pond liquor values sourced from reports ATC Williams (2019) attached in
Appendix C.
**Estimated upper limit, detection limits reported as half for the calculation.
Summary
In summary, no further geochemical analysis has been conducted on a combined Hydromet TSF sample, however both TSF 3 and Evaporation pond liquids have similar characteristics:
pH is circum neutral in both
Both have elevated Mg, S and Mo content and similar concentrations of Na and Ca
Given the above similarities, it is unlikely that combining the two streams will cause any reactivity of chemicals aside from the ammonium hydroxide, at a high pH.
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Table 5-13 Summary of Hydromet TSF 3 characterisation
Characterisation Hydromet TSF
Solids Liquids
AMD testing Suite of multi-elements/Salts
NAF No significant elevations expected
Circum Neutral/Saline
Elevations in Mg, NH4, S, SO4 Mo and F.
Physical Characteristic Sodic N/A
Fibrous materials testing None expected N/A
Radionuclides 32.4 Bq/g Insignificant levels expected
pH Expected to be between 6.6 and 7
Expected to be between 6.6 and 7
5.3.3 Conclusion
In conclusion, the Hydromet TSF contains elevated MgSO4 and thus the liner system provides
controls for the containment and encapsulation of these salts. The Beneficiation TSF tailings
solids are benign, i.e. unlikely to leach any significant concentrations of elements and are non-
radioactive. Table 5- summarises key elements in each TSF.
Table 5-14 Summary of key analytes for the TSFs*
Key element Beneficiation TSF Expected Hydromet TSF
Solids Liquids Solids Liquids
Fluoride - 2.6 mg/L - 4.1 mg/L
Molybdenum 4.7 0.037 mg/L 161 mg/kg <1 mg/L
Radionuclides 0.8 Bq/g - 33 Bq/g -
U Th
U = 8.4 mg/kg Th = 153 mg/kg
U = 0.002 mg/l Th = <0.001 mg/L
U = 104 mg/kg Th = 7,623 mg/kg
U = <1 mg/L Th = <1 mg/L
Mg - <1 mg/L 5,406 mg/kg 5,957 mg/L
SO4 (S = <0.01 %) 182 mg/L (S = 9.3 %) 27,066.3 mg/L
*Summary based on geochemical lab results, Appendix C, ATC Williams (2019) and ANSTO (2017).
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6. Design development concept6.1 General arrangement
The proposed general arrangement for the tailings facilities takes advantage of the natural
topography where a number of small gullies are formed between subtle rises at ground level.
These gullies are utilised to form the respective Beneficiation and Hydromet TSF embankments.
Initial starter dams are constructed to meet capacity requirements for the initial few years of
operation. Embankment raising can be completed by downstream construction methods.
Both the Beneficiation and Hydromet TSFs are kept within a single compact footprint by utilising
a common shared dividing wall between the two facilities. This minimises the overall area of
disturbance associated with tailings management at the site and minimises construction cost
and borrow pit requirements. There is also potential for the economical construction of a low
height dividing embankment within the Beneficiation TSF to create a small separate cell for the
Cleaner 2, 3 and 4 tailings (see location Figure 3-2).
The proposed TSF site impounds two adjacent gullies where there are respective watercourses
feeding into the downstream Fraser Creek tributary. During operations, any stormwater that falls
within the tailings dams will be contained and managed onsite and the upstream catchment will
be diverted around the TSF by constructing a new diversion channel.
At closure the TSF will be shaped and capped according to the final landform design with
excess stormwater able to be safely discharged back to the surrounding creeks via a series of
drains formed within the final TSF landform.
Figure 6-1 presents the Pre-Construction Design general arrangement for the TSF.
Figure 6-1 General arrangement of TSFs (after 3 years)
Beneficiation TSF
Hydromet TSF
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6.2 Concept details
6.2.1 Beneficiation TSF
The Beneficiation TSF requires the construction of an initial starter embankment, 6.5 m high at
maximum section to accommodate the first three years of production. Extension of the TSF after three years involves raising the perimeter embankments by approximately 4.5 m over the mine life. Adjustments also need to be made to the decant tower and access causeway including
relocation to its final southern location at the end of the mine life.
The proposed arrangement allows for spigotted perimeter discharge from the Beneficiation TSF embankment crest as well as elevated areas to the east and south. This will reduce the risk of
density variability or bleed water runoff affecting the beach slope and assist in beach development to create a central decant pond location.
For the proposed arrangement, a steep beach slope is not critical so there could be an option
for reduced thickening. However, due to the importance of water recovery, the TSF design assumes thickening of tailings. As such, there may be a need to control beach slope by spigot extension during operations and adopting elements of CTD in order to effectively fill the storage
and achieve a safe profile at closure.
To maximise water recovery and minimise spill risk, beaching of tailings will be directed at developing a pond located at the centre of the TSF and decanted using a central tower. The aim
is to remove water as quickly as possible with the intent to operate the TSF pond to the minimum size that is necessary to ensure water clarity for plant reuse.
Dusting from the tailings beach will be minimised by implementation of a rotational discharge
plan to apply tailings regularly in thin layers. The dust control plan will also incorporate a plan for contingency irrigation of dry beach areas as well as the application of dust suppressant chemicals as required.
6.2.2 Hydromet TSF
The Hydromet TSF requires the construction of an initial starter embankment, which will be 6 m maximum height to accommodate the first three years of production. Additional capacity after the initial three years is achieved by raising the perimeter embankment by approximately 3 m to
its ultimate height, which will provide sufficient capacity for the remaining mine life.
Due to the unsuitable water quality for plant reuse, there will be no water recovery from the Hydromet TSF. Rather, the Hydromet TSF will operate as an evaporation facility with adequate
freeboard to contain stormwater inflows without spill for a 1:100 AEP, 72 hr rainfall event.
Based on the expected low percentage solids of the combined Hydromet stream, a single point tailings discharge is envisaged.
Combining the Hydromet waste streams results in reduced dust risk from the original TSF 3 concept which relied on transfer of barren liquor from the evaporation pond and reduces the risk of low density waste, hence allowing a more simplified underdrainage system.
Due to the high sulphate nature of the Hydromet water the facility will require a lining system. The combined facility allows well proven liner technology using a combined compacted clay and HDPE liner system (i.e. geocomposite lining system).
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6.3 Water management
The Beneficiation TSF decant area will capture tailings bleed water and incidental run-off from
the catchment area associated with the TSF. This water will be returned to the process water
circuit via a water treatment/filtration plant for re-use.
The pumps required for the decant tower have been sized to allow for the expected runoff from
the initial settlement of the material allowing for expected evaporation and seepage into the
deposited tailings profile as per Table 6-1 below.
Table 6-1 Beneficiation decant recovery
Parameter Beneficiation TSF Unit
Production Solids 975,000 t/annum
Assumed Slurry Solids Content (Refer Note 1) 52 %
Assumed Initial Settled Density 1.1 t/m3
Assumed In Situ Dry Density (Desiccated) 1.5 t/m3
Annual Water in Slurry 900,000 m3/annum
Annual Volume Water Retained Following Initial Settlement
590,000 m3/annum
Annual Volume Water Released Following Initial Settlement (excludes evaporation loss)
310,000 m3/annum
Assumed Pond Depth 1 m
Pond Surface Area 31,000 m2
Pond Evaporation 49,000 m3/annum
Pond Seepage 35,000 m3/annum
Estimated Annual Decant Return (Refer Note 2) 120,000 m3/annum
Estimated Required Pump Capacity Range 25 - 50 m3/hour
Estimated Annual Loss to Tailings Deposit (Refer Note 2)
780,000 m3/annum
Note 1 – Tailings solids content as advised by Hastings 28th March 2019 based on thickening test work.
Note 2 – Settlement testing of combined beneficiation tailings is still ongoing. Estimated annual decant return assumes
50% loss due to evaporation from active beaches. This is to be confirmed in detailed design and final water balance
modelling.
Bleed water from the Hydromet TSF tailings will not be of sufficient quality to re-use as process
water and will remain in the impoundment during operation, to assist in dust prevention. Water
balance calculations indicate that due to the low discharge rate and high evaporation, a
significant decant pond will not form in the TSF.
Emergency spillways are proposed for both TSF impoundments at locations where they can be
cut into natural ground to ensure durability of the structure. The Hydromet TSF spillway will be
cut into the natural rock in an orientation allowing it to spill into the Beneficiation TSF,
minimising the environmental spill risk. The storage capacity of each TSF is conservatively
sized to ensure any spillway operation is a remote possibility.
The proposed TSF site impounds two adjacent gullies where there are respective watercourses
feeding into the downstream Fraser Creek tributary. During operations, any stormwater that falls
within the tailings dams will be contained and managed on-site, and the upstream catchment
will be diverted around the TSF by constructing a new diversion channel as indicated below in
Figure 6-2. At closure the TSF will be a capped according to the final landform design with any
excess stormwater able to be safely discharged back to the surrounding creeks via a series of
engineered drains formed within the final TSF landform.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 38
Figure 6-2 Watercourses and catchment area division around TSF site
6.4 Environmental risk and mitigation measures
Some aspects of the physical, geochemical and radiological properties of tailings and waste
water produced during processing plant operations are different to those of in situ soils and
groundwater. The potential for environmental degradation as a result of release of solids or
wastewater from their designated storage areas must be considered, and appropriate measures
put in place to minimise the likelihood and consequence of such release.
The principal mechanisms by which environmentally harmful materials could be released are:
Containment failure and spill risk
Dust generation (including radionuclide deportment)
Mobilisation of dissolved contaminants and high salinity liquor via seepage to groundwater
or surface water
Mitigating measures to prevent such releases to the extent that they could have an adverse
effect on the surrounding environment, are incorporated in the design and proposed operation
of the facilities. These measures are detailed below.
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6.4.1 Containment failure and spill risk
The tailings containment embankments have been designed specifically to prevent the
uncontrolled release of tailings and water from the TSF area and the facility location selected to
maximise natural topographic containment. Contingency measures to cater for extreme floods
and earthquakes have also been incorporated in the design.
The likelihood of containment failure is therefore very low since the consequences of such
failure have been considered and ameliorated in the consequence-based design process.
6.4.2 Dust management
Generation of dust from drying tailings beaches presents a potential environmental and health
risk, particularly for the case of the Hydromet TSF, where elevated radionuclides are present in
the tailings. The design and operational arrangement of both TSFs reduces the risk of dust
generation by:
The presence of continuous containment embankments elevated above the tailings
surface, will tend to break up wind flow and trap particles within the storage.
The presence of strong inter-particle forces due to the extremely fine grain size and
cohesive nature of the tailings.
Maintaining damp moisture conditions at the surface of tailings by frequent discharge of
layers in the beneficiation TSF and by combining spent liquor with tailings in the hydromet
TSF.
If dry surface conditions develop between tailings layer applications, Beneficiation TSF decant
water will be used to irrigate dry areas. Water will be applied using a low-ground pressure (LGP)
water cart developed to traffic on dry areas of the TSF.
A contingency plan for dust suppression in the event of prolonged dry conditions, such as plant
breakdown or temporary shutdown will include the application of dust suppressant chemicals
using the LGP water cart.
6.4.3 Groundwater seepage mitigation
The key identified risks associated with seepage from the TSFs include:
Impacts associated with contamination of downstream surface water receptors including
Fraser Creek
Impacts associated with the contamination of the groundwater aquifer below the TSF
potentially restricting the use of this water resource into the future
For the previous FS concept design, the likelihood of seepage from the TSFs or evaporation
pond coming into contact with groundwater or surface water external to the facilities was
considered to be very low (ATCW 2019). Conceptual seepage modelling completed by GHD for
the refined TSF arrangement supports this assessment (refer Seepage Analysis, Section 9.4).
Importantly, potentially environmentally harmful species contained in the tailings solids
(including radionuclides) have been assessed to be fixed or immobile, therefore the risk of
adverse environmental effects associated with seepage is primarily governed by the seepage of
transport water.
Dissolved materials in the tailings process liquor identified at concentrations above the NEPM or
ANZECC guideline values and /or local groundwater concentrations are detailed in Table 6-2.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 40
Table 6-2 Tailings liquor concentrations exceeding reference values
Facility Exceeding Analyte
Beneficiation TSF Fluoride (F) Molybdenum (Mo) pH
Hydromet TSF Fluoride (F) Magnesium Sulphate (MgSO4)
Fluoride levels are above the livestock watering guideline concentration of 2 mg/l, as are
concentrations measured in the regional groundwater bores, generally being between 2 mg/l
and 3 mg/l.
The livestock watering guideline concentration for Molybdenum is 0.15 mg/l. Molybdenum
concentrations in the regional groundwater bores are below the guideline concentrations,
generally below 0.03 mg/l. Concentrations measured in the beneficiation tailings exceed
guideline limits.
Magnesium Sulphate as a compound is generally not considered a hazardous substance.
Notwithstanding this, the associated TDS and sulphate concentrations in the Hydromet TSF
combined liquor are elevated above the respective livestock watering guideline concentrations
of 5000 mg/l and 1000 mg/l, respectively.
Mitigating conditions and measures to prevent environmental impact associated with seepage
include:
Maintaining unsaturated beaches and a small central decant pond within the Beneficiation
TSF to minimise seepage and increase the offset between the pond and potential
downstream receptors.
Selecting TSF locations where the inferred foundations comprise in excess of 45 m of
unsaturated, low-permeability materials will provide an effective aquitard between ground
surface and the confined aquifer (ATCW 2019). Any small rates of seepage would be
subject to dilution by groundwater flow within the aquifer.
Analysis shows that the development of a wetting front below the decant pond is localised
and is not anticipated to significantly extend laterally beyond the footprint of the TSF.
Leaching of metals from the tailings solids is not anticipated based on testing.
A high standard geocomposite liner system is included in the design of the Hydromet TSF.
Groundwater monitoring provisions are incorporated in the design and operating plan for
the facilities.
The TSF will be closed as a capped facility. The very low rainfall and high evaporation
climate should ensure negligible rates of infiltration and long term seepage from the facility.
In addition, the Hydromet TSF cover system incorporates a geosynthetic liner to further
minimise infiltration and seepage risk.
Detailed design for proposed TSF will include additional geotechnical investigations and
verification of the conceptual hydrogeological model and seepage modelling undertaken for the
concept design. Additional mitigation measures that could be considered (if required) in detailed
design include:
The treatment of any identified preferential seepage paths between the TSF and
downstream receptors using a barrier system such as cement grouting or the construction
of a cut-off wall.
Contingency interception systems such as trenches or recovery bores.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 41
Additional lining below the proposed pond location within the Beneficiation TSF.
Geosynthetic lining of collection drains within the final TSF landform to further reduce long
term seepage rates.
6.5 Closure and rehabilitation concept
6.5.1 General requirements
The closure plan for the Yangibana TSFs will be similar to that already described in the ATCW
FS Concept Report (ATCW 2019). Closure will conform with DMIRS guidelines to develop a final landform that is:
Physically safe to humans and animals
Geotechnically stable
Geochemically non-polluting/ non-contaminating
Capable of sustaining an agreed post-mining land use
Decommissioned and rehabilitated in an ecologically sustainable manner
6.5.2 Closure design
Based on the geometry and expected condition of the TSFs at completion of operations and taking into account the geochemical and radiological characteristics of the tailings materials, the
conceptual closure methodology is summarised below. This is consistent with that presented in ATCW 2019 which GHD considers to be appropriate.
Figure 6-3 and Figure 6-4 show the general arrangement envisaged following closure as well as
the conceptual capping sequence proposed for the respective TSFs. The closure concepts illustrated in this report have been developed in line with the Landform Evolution Study undertaken by Trajectory as documented in Table 6-3.
Table 6-3 TSF closure specification
Specification Consideration in TSF Design
Maximum 40 m lift height (provides conservatism against model).
The maximum height of either TSF is approximately 9m and 11m respectively.
Average slope angle 17.5 degrees. During operation and leading into closure the downstream batters will be re-profiled to 15 degrees in the lower 50% and 20 degrees in the upper 50% ensuring an average slope angle of 17.5 degrees.
20 degrees in upper 50% of Slope and 15 degrees in lower 50% of slope
During operation and leading into closure the downstream batters will be re-profiled to 15 degrees in the lower 50% and 20 degrees in the upper 50% ensuring an average slope angle of 17.5 degrees.
Hydrology measures to PMP required to limit run-on from top surface or berms to batters below. Nominal 1 m crest bund.
Cover according to landform design objectives. Operational TSF pond will be removed via construction of a spillway/channel into bedrock. Drains in final TSF landform can safely discharge any excess stormwater, engineering to withstand/avoid scour in long term.
Cell bunding of 0.7 m and perimeter bunding of 1 m. Infiltration + Evapotranspiration > 100% of incident rainfall on flat surfaces.
To be detailed in Mine Closure Plan as required.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 42
Specification Consideration in TSF Design
Berms for 20 m high batters (Bald Hill) are 20 m wide after reprofiling.
To be detailed in Mine Closure Plan as required.
0.5 m high bunds at 10 m offset from final toe position. Cross bunds installed where natural ground at gradient greater than 2 degrees.
To be detailed in Mine Closure Plan as required.
Rip lines on contour and minimum 0.5 m deep and 1 m wide at base of windrow.
To be detailed in Mine Closure Plan as required.
40% of exposed surface comprised of durable fraction equal to or greater than gravel.
To be detailed in Mine Closure Plan as required.
Armouring subsoils spread at 150 – 200 mm over reprofiled waste rock. 20% of final exposed surface after 3-year stabilisation period will be gravels/cobbles from the soil.
To be detailed in Mine Closure Plan as required.
Minimum 2 m of in situ or imported durable armouring granite waste rock over embankments after final reprofiling.
The embankment will be constructed using mine waste rock with a minimum 2 m cover used in the reprofiling of the TSFs to meet the slope specifications noted above. Planning to be detailed in Mine Closure Plan.
Provenance seed mix of grasses, shrubs and woody plants.
To be detailed in Mine Closure Plan.
Include introduction of biological matter and soil inoculants in revegetation process.
To be detailed in Mine Closure Plan.
Provenance seed mix of grasses, shrubs and woody plants.
To be detailed in Mine Closure Plan.
Beneficiation TSF
The final geometry of the Beneficiation TSF will allow for safe drainage of any excess stormwater to a spillway channel cut through natural ground to the south. The tailings surface will be shaped to suit, with drain gradients making allowance for settlement. Capping of the TSF
will include placement of a nominal 500 mm thick layer of benign mine waste rock, topped with a nominal 200 mm thick layer of topsoil.
The final slope profile for the downstream face of the TSF allows for a grade of 20˚ on the upper
portion and 15˚ in the lower portion by placement of benign waste rock on the downstream face.
Hydromet TSF
The closure concept for the Hydromet TSF allows for the placement of a minimum 1 m of beneficiation tailings over the Hydromet tails, followed by placement of a HDPE liner welded to
the basal liner to fully encapsulate the Hydromet tailings. A 300 mm thick “cushion layer” of beneficiation tailings will be placed over the HDPE followed by 500 mm of benign waste rock and 200 mm topsoil. The various layers will be shaped to result in a surface draining to a stable
spillway channel in natural ground located to suit the final level achieved. If the Hydromet TSF is higher than the Beneficiation TSF then drainage will be matched to the Beneficiation TSF closure surface and use the same spillway channel.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 43
Figure 6-3 TSF closure concept general arrangement
Figure 6-4 TSF concept capping design
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 44
7. Consequence based designrequirements7.1 General
Specific design requirements for tailings dams are given by DMIRS (formerly DMP) and
ANCOLD depending on the TSF type and classification.
Consequence based classification of a TSF is primarily based on an assessment of the potential extent or severity of impacts due to embankment failure or uncontrolled release of tailings
and/or water, should such events occur. This assessment is supplemented by consideration of embankment height (DMIRS) or the number of people likely to be impacted (ANCOLD). The following are initial screening level assessments subject to review at detailed design.
7.2 DMIRS TSF characterisation
In accordance with the requirements of the DMP Code of Practice for Tailings Storage Facilities in Western Australia (Code of Practice), a hazard rating for the TSFs has been prepared to
determine the appropriate TSF category. Hazard Rating assessments are noted in Table 7-1.
Table 7-1 DMIRS TSF characterisation
Type Extent/Severity of Impact Beneficiation TSF Hazard
Rating
Hydromet TSF Hazard
Rating
Release of Tailings Water or Seepage
Loss of human life or personal injury
Possible though not expected. Low Low
Adverse human health
Possible though not expected. Low Medium
Loss of assets Not expected due to the location and lack of infrastructure downstream.
Low Low
Environmental or heritage damage
Given the geochemistry of the material heritage and environmental damage is not expected for Beneficiation TSF with a potential for the Hydromet TSF.
Low Medium
Embankment Failure
Loss of Human Life Potential for loss of human life dependent on itinerants on haul road downstream.
Medium Medium
Adverse human health
Not expected for the beneficiation TSF however potential for the Hydromet TSF.
Low Medium
Loss of assets Expected due to loss of TSF. Medium Medium
Environmental or heritage damage
Transportation of sediments into the local waterways expected to impact surface water quality.
Medium Medium
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 45
7.2.1 Beneficiation TSF
With a maximum height in the range of 5 to 15 m the Beneficiation TSF is classified as Category
2 for Release of Water and for Dam Failure.
7.2.2 Hydromet TSF
With a maximum height in the range of 5 to 15 m the Hydromet TSF is classified as Category 2
for Release of Water and for Dam Failure. This is a reduced hazard rating relative to the original
FS concept design due to the assessed lesser impact associated with failure of the Hydromet
TSF relative to TSF3 (i.e. significant tailings stack height reduction).
Notwithstanding this, the revised pre-construction design still adopts more conservative
category based design criteria for both the Beneficiation and Hydromet TSF relative to the FS
concept as described in Section 7.4.
7.3 ANCOLD consequence category
Preliminary assessments of the Consequence Category for the Beneficiation TSF and Hydromet
TSF have been undertaken, as per ANCOLD guidelines (ANCOLD, 2012b). The Consequence
Category assessment guides the pre-construction design, operation and maintenance
requirements for the storages.
7.3.1 Beneficiation TSF
Dam failure consequence category
The following assumptions have been used to develop the Consequence Category assessment
for the Beneficiation TSF:
The costs for the infrastructure and dam replacement and clean-up costs would be likely to
exceed 10 million dollars but be less than 100 million dollars giving a medium level ofdamage (assessed under ANCOLD).
The impact of a sunny day failure on the dam owners business is ‘Major’ as the operation of
the tailings dam is critical to the ongoing extraction and processing of the rare earthminerals and would lead to major economic impacts.
The impact of a dam failure on health and social impacts is minor due to the regional
location of the dam.
The environmental impacts of a sunny day failure of the embankment is minor due to thebenign nature of the material and low expected radiological impacts.
The environmental impacts of a flood loading failure scenario are considered to bemoderate due to the benign nature of the material and the lack of expected long-termeffects of the material within the surrounding environment.
Population at Risk (PAR) in flow path in case of failure would be limited to itinerants givenno current permanent residences or mine facilities downstream. However, flooding couldaffect the site haul road. Arguably the PAR could be <1 but conservatively between 1 and
10.
Utilising these assumptions, the TSF embankment has been assigned a Consequence
Category of Significant (consistent with ATCW 2019) or High C dependant on the
adopted PAR. For the purpose of Pre-Construction Design, High C is adopted to ensure
the use of conservative category based design parameters.
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Environmental spill consequence category
The Environmental Spill Consequence Category for the Beneficiation TSF has been assessed
as Low, due to the benign nature of tailings, and relatively low environmental risk posed by the pond water following a short term spill event.
7.3.2 Hydromet TSF
Dam failure consequence category
The following assumptions have been used to develop the Consequence Category assessment
for the TSF:
The costs for infrastructure and dam replacement and repair costs are estimated to bebelow 10 million dollars giving a low level of impact (assessed under ANCOLD).
The impact of a sunny day failure on the dam owners business is ‘Major’ as the operation ofthe tailings dam is critical to the ongoing ore extraction and mineral processing.
The impact of a dam failure for sunny day loading on health and social impacts is minor due
to the regional location of the dam.
The environmental impacts of a sunny day failure of the embankment is major.
The environmental impacts of a flood loading failure scenario are considered to be major
due to the nature of the material and the lack of expected long-term effects of the materialwithin the surrounding environment.
Population At Risk (PAR) in flow path in case of failure would be limited to itinerants given
no current permanent residences or mine facilities downstream. However, flooding couldaffect the site haul road. Arguably the PAR could be <1 but conservatively between 1 and10.
Utilising these assumptions, the TSF embankment has been assigned a Consequence
Category of Significant or High C dependant on the adopted PAR. For the purpose of Pre-Construction Design, High C is adopted to ensure the use of conservative category based
design parameters.
Environmental spill consequence category
The Environmental Spill Consequence Category for the Hydromet TSF has been assessed as
Significant due to the increased environmental risk resulting from a spill due to the increased
concentration of Magnesium Sulphate and the concentration of radionuclides within the
material.
7.4 Category based design criteria
7.4.1 Design criteria
Based on the assessed dam failure and spill consequence category, the fall-back design criteria
suggested by ANCOLD 2012 prevail and give more conservative freeboard and stormwater
storage capacity requirements relative to the DMIRS minimum requirements.
The specific design requirements resulting from the consequence-based categorisation of the
TSFs are as follows in Table 7-2.
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Table 7-2 Design criteria from consequence category
Design Criteria Beneficiation TSF Hydromet TSF
Stormwater Storage Capacity 1:5 wet season plus 1:100 AEP, 72 hr flood
1:10 wet season plus 1:100 AEP, 72 hr flood
Additional Freeboard nil 1:10 AEP wind runup plus 0.3 m
Spillway 1:100,000 AEP, critical flood plus 1:10 AEP wave run-up or PMF
1:100,000 AEP, critical flood plus 1:10 AEP wave run-up or PMF
Seismic Loading
Operation Based Earthquake (OBE)
1:1000 1:1000
Maximum Design Earthquake (MDE)
1:10,000 1:10,000
Closure MCE approximated to 1:10,000 AEP
MCE approximated to 1:10,000 AEP
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8. Pre-construction design details8.1 Construction materials and site clearing
Prior to bulk earthworks and embankment construction, the impoundment and embankment
footprint areas will be cleared, grubbed and stripped of topsoil to a nominal thickness of 200 mm and stockpiled for later use in the rehabilitation of the site.
The materials required to construct the low permeability zones within the embankments will
largely be sought from external borrow pit areas but where possible from within the storages. Borrow pit areas are currently under investigation by Hastings. The select earthfill and gravel materials (structural fill) will be sought from the pit overburden material stockpiled on site. An
onsite rock borrow pit (with mobile crushing plant) will be established to produce pavement materials for site access roads and the embankment crest roads.
The near surface clayey sand deposits within the Beneficiation TSF footprint will be retained to
assist with seepage control.
The Hydromet TSF will incorporate a HDPE geomembrane placed across the impoundment floor and on the upstream face of containment embankments. The in situ clayey sands will be
retained and reworked to form a compacted clay liner below the geomembrane. In areas lacking a suitable thickness of in situ clay, soils from an external borrow pit will be imported to form the base clay liner for the floor of the Hydromet TSF.
8.2 Beneficiation TSF
8.2.1 Storage characteristics and embankment design
The starter dam design for the Beneficiation TSF features an embankment crest width to enable light vehicle access only. The upstream face will have a 2:1(H:V) batter slope to maximise
tailings storage and minimise construction material. The downstream face will have a 2.5:1 (H:V) batter slope which is considered suitably conservative to achieve geotechnical stability requirements. Sufficient space will be maintained between the dam toe and the lease boundary
to allow for further design raises and the closure batter flattening works. The starter dam for the Beneficiation TSF features the geometry as listed below in Table 8-1.
Table 8-1 Beneficiation TSF starter embankment geometry
Description Design
Starter Dam Height ~ 6.5 m
Minimum crest width 7 m
Embankment Length 1,600 m
Upstream batter slope 1:2.0 (V:H) – Starter Dam
Downstream batter slope 1:2.5 (V:H) – Starter Dam (flattened for closure, see Section 6.5)
Zoning Upstream clay and downstream general selected earthfill
The estimated total storage requirement for the Beneficiation TSF is approximately 6.5 Mm3.
The estimated storage capacity of the Stage 1 starter dam is approximately 2.5 Mm3, sufficient
for the first 3 years only. At a filling rate of 0.65 Mm3pa, the TSF would operate with conventional spigot discharge from the northern and eastern embankments for the initial 2 years, with additional capacity developed by extending spigots and discharge from higher
elevations to the east and south. To achieve the necessary storage capacity for the mine life volume, the perimeter embankments will need to be raised by approximately 4.5 m. The design conservatively assumes raising using downstream construction methods.
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The Pre-Construction Design Drawings presented in Appendix A provide staging drawings for
the TSF over the mine life.
A storage curve for the Beneficiation TSF is presented in Figure 8-1. Note that this applies to a
flat tailings surface whereas the actual volume estimates to determine the required embankment
heights have considered the beach development around the TSF giving the benefit of
increasing storage due to beaching around the south and east of the facility.
Figure 8-1 Beneficiation TSF storage curve
The design embankment for the Beneficiation TSF embankment incorporates three zones:
Zone 1: Upstream sloping low permeability zone (clayey materials).
Zone 3A: Downstream general select earthfill (general structural fill).
Zone 2: Select sandy gravel if necessary for desiccation prevention on the surface of theupstream clay zone (subject to construction and tailings filling schedule).
A typical section of the embankment is shown in Figure 8-2 below.
Figure 8-2 Beneficiation TSF embankment typical section
To reduce potential seepage beneath the embankment, the design allows for excavation of a cut-off trench at the upstream toe that is excavated to moderately weathered bedrock. The
excavated trench will be backfilled with compacted Zone 1 material.
0
1000000
2000000
3000000
4000000
5000000
6000000
326 328 330 332 334 336 338 340
Storage (m3)
RL(m)
Beneficiation TSF Storage Curve (Flat)
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It is envisaged that Zone 1 construction material will primarily be sourced from nearby borrow pit
areas where clayey sand is available at a suitable thickness. The clayey soils from borrow pit
areas in the vicinity of the TSF may be supplemented by clayey (saprolitic) material recovered
during stripping at the Bald Hill pit.
The in situ moisture content of the clayey borrow pit materials is generally expected to be lower
than optimum moisture content at the time of construction; consequently, moisture conditioning
by adding water during construction is anticipated to optimise compaction. Based on laboratory
test data, in situ moisture content at the time of the investigation was generally 2% - 5% below
OMC, except at the location of test pit CTTP-03 where moisture content was 4% wet of
optimum.
External borrow pit sources of clayey sand typically ranged from between 1.5 m and 2.0 m in
depth. ATCW geotechnical investigations found that the clayey materials in the vicinity of the TSF
have moderate to low dispersion potential, inhibited to some extent by the presence of calcium
carbonate (Emerson class 4). Dispersion and erosion on the upstream slopes of the
embankments will be minimised by the accumulation of tailings against the low permeability zone.
Zone 3A material will be sourced from pre-stripping operations at Bald Hill and will be used to
form the bulk of the embankment volume, possibly combined with residual materials excavated
from borrow pit areas in the vicinity of the TSF.
8.2.2 Tailings deposition and decant pond
Tailings deposition within the Beneficiation TSF will involve perimeter discharge in frequent and
uniform cycles around the facility via a 280PN20 HDPE pipeline with spigots nominally spaced
at 50 m intervals. A new perimeter access road will need to be constructed with sufficient width
to accommodate the tailings discharge pipeline so that tailings beaches can be gradually
formed around all sides of the facility. The spigots would extend down the face of the
embankment and reservoir slopes and depending on the beach slope achieved during
operations, be extended out onto the tailings beach to develop an optimal beach shape.
Towards the end of mine life, elements of Central Thickened Discharge (CTD) would be
adopted to effectively fill the storage and achieve a safe closure surface.
At the commencement of operations, tailings deposition will focus on quickly pushing the pond
away from the main embankment to the proposed initial decant tower location. This will be aided
by a new channel excavated into the floor of the TSF to connect the decant tower with the valley
low point. This will allow decant water to be returned to the plant at the earliest opportunity.
Later in the operational life of the TSF, a new decant tower will be constructed towards the
southern end of the facility so that the pond can be relocated to its ultimate location, where a
discharge channel will be excavated through rock at closure (refer Closure and Rehabilitation
Concept, Section 6.5).
The decant towers will be accessed by a new causeway construction from readily available fill materials. The decant causeway will be raised and/or relocated as part of the construction works associated with raising of the TSF, most likely at 3 years and 6 years into operation.
The proposed decant tower will be a slotted concrete ring type of decant arrangement whereby
ponded water decants through slots in the side of a concrete ring tower which is raised
incrementally to remain elevated above the rising tailings. A variable speed submersible pump
will be installed at the base of the tower for water return to the plant.
Staged general arrangement plans are presented in the Pre-Construction Design Drawings in
Appendix A.
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8.2.3 Emergency spillway design
The Beneficiation TSF includes the initial construction of an emergency spillway excavated through natural ground on the southern side of the facility. Conceptually, the spillway is
nominally set 1 m below the TSF embankment crest level with the tailings beach lowered to suit in this location.
A nominal spillway width of 50 m has been adopted which provides ample capacity to pass the
PMF event. Below the spillway level there is sufficient capacity to accommodate the combined wet season storage and extreme storm storage capacity (refer Stormwater Storage Assessment, Section 9.1). The final spillway location at end of mine life will be through a granite
ridgeline on the southern side of the facility to ensure long term stability.
8.3 Hydromet TSF
8.3.1 Storage characteristics and embankment design
The Hydromet TSF tailings will be of neutral pH, are not acid forming and test work has
demonstrated that solution and mobilisation of dissolved metals (including radionuclides) from the tailings deposit is not expected as a result of infiltration. Nevertheless, the incorporation of a liner system for the Hydromet TSF has been adopted due to the elevated salinity of the
magnesium sulphate solution, which is used to slurry the Hydromet plant residue and the Barron Liquor.
To minimise seepage the Hydromet TSF features a geocomposite lining system that comprises
a minimum 300 mm thick compacted clay liner (CCL) below a HDPE liner. This is a well proven lining system that is commonly used in industry for containment of hazardous mining and landfill wastes.
The Hydromet TSF storage cell abuts the Beneficiation TSF on its western side and forms a closed storage area. Embankment construction consists of a Zone 3A select earthfill sourced from the pit overburden and a sloping impermeable Zone 1 on the upstream face and an
impermeable HDPE liner. As a result, an upstream erosion protection layer is not required.
The starter dam design for the Hydromet TSF features an embankment crest width to enable light vehicle access only. The upstream face will have a 3:1(H:V) batter slope that is suitable for
application of the lining system. The downstream face will have a 2.5:1 (H:V) batter slope which should be suitably conservative to achieve geotechnical stability requirements. The starter dam for the Hydromet TSF features the geometry as listed below in Table 8-2.
Table 8-2 Hydromet TSF starter embankment geometry
Description Design
Starter Dam Height ~ 6 m
Minimum crest width 7 m
Embankment Length ~ 2,000 m
Upstream batter slope 1:3.0 (V:H) – Starter Dam
Downstream batter slope 1:2.5 (V:H) – Starter Dam (flattened for closure, see Section 6.5)
Zoning Upstream clay and downstream general selected earthfill
The estimated total storage requirement for the Hydromet TSF is approximately 1.9 Mm3.
The estimated storage capacity of the Stage 1 starter dam is 0.45 Mm3, sufficient for the first 3 years. After the initial 3 years of operation, the Hydromet TSF would be raised by approximately 3.0 m to its proposed ultimate height. Raising would be completed by downstream construction
with an allowance to join and extend the lining system on the upstream face up to the ultimate height.
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The design for the Hydromet TSF embankment incorporates two primary zones:
Zone 1: Upstream sloping, low permeability zone (clayey materials) that forms part of the
geocomposite lining system for the TSF.
Zone 3A: Downstream select mine waste rock or impoundment excavation materials.
A typical section of the embankment is shown in Figure 8-3 below. This is a robust design
utilising downstream construction methods to ensure a very low probability of dam failure.
Figure 8-3 Hydromet TSF embankment typical section
8.3.2 Tailings management
The Hydromet TSF will receive the combined Hydromet waste stream in a single pipeline
extending around the embankment crest access road. The TSF will be commissioned with single point discharge to fill the valley section of the TSF where the tailings deposit will be deepest and less consolidated due to the initial higher rate of rise. Within this valley section, a
network of underdrains can be installed above the liner to assist with consolidation of the low density tailings. The requirement for these valley underdrains will be confirmed in detailed design.
Due to the low solids tailings, a flat beach is expected to develop within the TSF and the base is substantially covered within the first year of operation. At this point in time an evaporation balance is achieved and tailings density will be further increased by drying. At the end of mine
life, the average depth of Hydromet tailings is expected to be approximately 4.5 m. This is a conservative estimate based on an assumed average 0.5 t/m3 final density.
The concept design for the underdrains installed under the tailings within the valley section of
the TSF comprises the use of multiple panel (e.g. Megaflo) collection drains to maximise drain surface area and promote water recovery. A collection sump would be constructed and fitted with a submersible pump for recovery and return of water to the surface of the TSF, the intent
being to promote consolidation and to increase tailings density in the deeper valley section of the facility.
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Figure 8-4 Megaflo panel drain examples (courtesy Geofabrics Australia)
8.3.3 Emergency spillway design
The Hydromet TSF includes the construction of an emergency spillway sized to safely pass a
PMF event without overtopping of the embankment. The spillway will initially be excavated
through rock on the northeast corner of the TSF, allowing spills to be directed to the
Beneficiation TSF decant pond, which has a larger capacity to store extreme flood events.
Nominal dimensions of 20 m wide and 600 mm deep have been adopted.
Below the spillway level there is sufficient capacity to accommodate the combined wet season
storage and extreme storm storage capacity (refer Stormwater Storage Assessment, Section
9.1).
8.3.4 Geomembrane selection and installation considerations
The Hydromet TSF design features a geocomposite liner system which comprises a
geomembrane overlying a compacted clay liner. The compacted clay liner plays an important
role in forming a smooth and unyielding subgrade and also restricts leakage rates due to any
defects within the overlying geomembrane.
For the purpose of pre-construction design, High Density Polyethylene (HDPE) geomembrane
has been selected as the preferred geosynthetic liner. HDPE geomembranes are
manufactured by combining a polymer resin (>95%), with additives such as antioxidants,
stabilizers, plasticizers, fillers, carbon-black, and lubricants (as a processing aid). These
additives enhance the long- term performance of geomembranes by protecting the
polyethylene from degradation (Ewais and Rowe 2014).
HDPE is commonly used for waste containment as it exhibits high strength and chemical
resistance to a wide range of chemicals. Significant experience and data also exists relating to
the long term performance and service life for HDPE liners. HDPE geomembranes are
extremely durable products, designed with service lives of up to several hundreds of years
under a broad range of environmental conditions.
The service life of HDPE geomembranes has historically been determined by its half-life, which
is the point at which the 50% depletion level of antioxidant additives occurs. This is not
considered appropriate for estimating the service life of a HDPE geomembrane for containment
purposes (Rowe 2012), as although the design property, e.g., depletion of antioxidant additives,
may be reduced by 50%, the mechanical properties of the geomembrane enable it to function
as a hydraulic barrier for considerably longer.
In practice, a number of variables will determine the actual lifespan of any geomembrane.
Factors that influence the lifespan of a geomembrane are the material properties of the
geomembrane – physical, mechanical, durability and performance properties, the compatibility
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of the geomembrane with site-specific conditions including tailings leachate chemistry, clay
liner, subgrades, foundations and applied stresses, the operating conditions of the facility
including temperature, UV light from exposure, ionising radiation, installation, backfilling and
construction factors.
The Hydromet TSF includes numerous factors to minimise potential degradation of the lining
system as detailed below:
Selection of a white HDPE geomembrane. The lifespan of HDPE geomembranes
reduces drastically at elevated temperatures because higher temperatures act as catalysts
that speed geomembranes’ degradation reactions such as antioxidant depletion, chemical
degradation and UV degradation. Even at moderate temperatures, a black geomembrane
can become very hot, making it prone to wrinkling or folding, and in the process losing
contact with its foundation.
Under the recorded month average air temperature range at the proposed TSF site (21-
41°C), selection of a white reflective liner should result in a liner temperature on average
21–23°C cooler than its carbon black counterpart, with correspondingly less risk of
wrinkling and installation defects that may lead to developing stress cracks (Rentz et al.
2017).
Critically, a 20°C reduction in temperature avoids thermal regimes where recrystallisation
of polymers can occur which can lead to rapid onset of failure of the liner.
For exposed portions of the HDPE liner, exposure to UV can decrease the expected or
predicted lifespan by a factor of seven (GeoSynthetics Institute). Selection of a white liner
(achieved by the addition of titanium dioxide and associated HALS and UV stabilisers) will
reflect most of the UV light reaching the surface of the liner, ultimately prolonging its
lifespan.
Selection of appropriate additives. To combat geomembrane degradation at higher
temperatures, selection of an appropriate additive antioxidant composition able to resist
significant loss of mechanical and performance properties at elevated temperatures is
proposed. It is anticipated that during detailed design, design of additive composition will
include careful consideration of the tailings leachate chemistry, thermal regime and
exposure to ionising radiation.
The presence of low level ionising radiation (approximately 35Bq/g) is anticipated to have
an impact on the rate of antioxidant consumption. Recent studies by Tian et al. (2017)
indicate that low level radioactive leachates can promote radiative oxidation that consumes
antioxidant consumption on the order of approximately 10% faster than non-radioactive
leachate alone. Much of the impact of α and β radiation would be mitigated by placement of
a thin layer of benign tailings on the liner prior to deposition of radioactive tailings due to
the fact that radionuclides are non-mobile in the tailings.
Selection of an appropriate liner thickness. All other factors considered, the thickness of
the HDPE liner has a direct relationship to its service life due to increased availability of
stabilisers and antioxidants and increased stress crack resistance of the liner. It is
anticipated that a liner of between 1.5 and 2.0 mm in thickness will be required to achieve
the desired service life.
Construction Methodology. The smoothness, uniformity, and density of the subgrade and
the quality of the installation – lack of wrinkles, intimate contact with subgrade, seams,
penetrations, minimum extrusion welding, minimum shear stress on slopes are perhaps the
most critical factor affecting liner life after material composition.
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An example of a detailed construction and testing methodology is attached, which outlines the typical controls and hold point put in place to ensure development of an appropriate
construction methodology and QA/QC process to ensure that it is correctly implemented.
QA/QC. The QA/QC process for the HDPE liner installation will also be a critical aspect of
construction involving seam testing as well as destructive testing of liner samples. Post
installation of the HDPE liner, electrical leak detection testing shall be carried out involving
both arc and dipole test methods as follows:
– Standard Practice for Electrical Leak Location on Exposed Geomembranes Using the
Arc Testing and/or Water Puddle Testing Method (ASTM D 7002 and/or ASTM 7953).
– Standard Practice for Electrical Method of Locating Leaks in Geomembrane Cover with
Water or Earth Materials ASTM D 7007 on the pond base.
The attached draft geosynthetic lining specification details the typical QA/QC testing and construction supervision requirements typically implemented to supervise the construction of a composite geomembrane lining system.
TSF Operation. In addition to designing specialised geomembrane polymer compositions
for resisting degradation, their degradation may also be reduced by a protective thick layer
tailings to take advantage of relatively lower geothermal ground temperatures
(approximately 17°C). For exposed portions of the liner, leachate trickle systems may be
considered to increase evaporative loss of decant water whilst simultaneously cooling the
exposed portion of the liner.
Further details on the above measures to ensure the required service life of the HDPE geomembrane are detailed in the attached generic geomembrane specification (Appendix H).
It is considered that, given the anticipated physical, climatic, chemical and other constitutive
factors anticipated for the proposed TSF, an appropriately selected HDPE geomembrane together with proper construction techniques (including adequate construction quality assurance), and by laying the geomembrane over a well-graded smooth foundation, service life
in the hundreds of years is readily achievable.
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9. Specific design studies 9.1 Stormwater storage assessment
9.1.1 General
Stormwater storage capacity and freeboard allowances during mine operation have been
determined for the TSFs in accordance with ANCOLD requirements.
For the purpose of determining the required stormwater storage capacity, the TSF catchment
system comprises both embankments and their catchments.
9.1.2 Storage requirements and freeboard
Freeboard and stormwater storage allowance as defined in ANCOLD 2012 is illustrated below in
Figure 9-1.
Figure 9-1 ANCOLD freeboard definition
For the Beneficiation TSF, the 86 ha catchment comprises of the upstream impoundment area
accounting for construction of the upstream diversion drain. This catchment area is applicable
from commissioning until closure.
For the Hydromet TSF, the catchment incudes the full impoundment area defined by the
downstream crest of the final embankments. The catchment area for the storage is 36 ha for the
TSF.
For stormwater storage and freeboard assessment it is conservatively assumed that there is
zero infiltration loss during rainfall and wet season events.
To mitigate the risk of environmental spill, the freeboard for each of the TSFs in the initial three
years has been assessed assuming no decant recovery during a 1:100 year, 72 hr storm event.
The calculated stormwater storage and freeboard requirements for the respective TSFs are
given in Table 9-1. This shows that the Normal Maximum Operating Level (NMOL) for the
Beneficiation TSF and Hydromet TSF decant pond is 2.0 m and 1.15 m respectively below the
spillway level in each facility.
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Table 9-1 Freeboard and stormwater storage requirements
TSF Freeboard Component Freeboard Volume (m3)
Freeboard Depth (m)
Beneficiation TSF Spill Consequence Category = Low
Wet Season Storage Allowance (1:5 AEP)
260,000 1.4
Extreme Storm Storage (1:100 AEP, 72 hr)
215,000 0.6
Contingency Storage (Contingency including waves)
0 0
Total (depth/capacity between spillway and Normal
Minimum Operating Level (NMOL))
475,000 2.0
Hydromet TSF Spill Consequence Category = Significant
Wet Season Storage Allowance (1:5 AEP)
105,000 0.3
Extreme Storm Storage (1:100 AEP, 72 hr)
90,000 0.25
Contingency Storage (Contingency including waves)
210,000 0.6
Total (depth/capacity between spillway and NMOL)
405,000 1.15
9.2 Flood hydrology
9.2.1 Hydrological modelling
Hydrological modelling was undertaken to assess the capacity requirements of the water management structures associated with the TSF including spillways and diversion drain.
This section summarises the process used in determining the capacity requirements. Modelling of the rainfall routing through the storages was undertaken utilising RORB software to determine the critical duration, expected flows and height of water in the storages.
Design rainfall events
In order to determine design rainfall events, the Generalised Short Duration Method (GSDM) and the Revised Generalised Tropical Storm Method (GTSMR) were used, as outlined in ‘Australian Rainfall and Runoff: A Guide to Flood Estimation’ (Ball et al., 2016), in conjunction
with Intensity Frequency Duration (IFD) data obtained from the Bureau of Meteorology.
Figure 9-2 presents design rainfall events for various AEPs and storm durations.
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Figure 9-2 Design rainfall IFD curves
Hydromet TSF
Due to the arrangement of the facility, the catchment of the Hydromet TSF is limited to the internal area and external crest footprint, equating to 36.2 ha.
A graphical representation of the modelling results is presented in Figure 9-3.
The operational level of the TSF was modelled as 250 mm above the tailings level to allow for the 1:100 AEP 72 hour rainfall event at the commencement of the design flood event. This is in
excess of the Normal Maximum Operating Level which ensures a conservative estimate of spillway discharge.
Figure 9-3 Hydromet TSF hydrograph (critical duration)
As per the Consequence Category assessment (see Section 7.3), the TSF is required to pass a PMF flood event. The modelling completed found the critical event to be 12 hours, with a peak
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inflow of 15.4 m3/s and a peak outflow of 8.5 m3/s. The proposed spillway arrangement ensures adequate capacity to pass a PMF rainfall event without overtopping of the TSF embankment.
Beneficiation TSF
Due to the arrangement of the facility, the catchment of the TSF is limited to the internal area of the facility and the external catchment upstream of the footprint, equating to 106 ha.
A graphical representation of the modelling results is presented in Figure 9-4.
The operational level of the TSF decant pond was conservatively modelled as 1.0 m below the spillway crest at the commencement of the design flood event. This is in excess of the Normal Maximum Operating Level which ensures a conservative estimate of spillway discharge.
Figure 9-4 Beneficiation TSF hydrograph (critical duration)
As per the Consequence Category assessment (see Section 7.3), the TSF is required to pass a PMF flood event. The modelling completed found the critical event to be 4 hours, with a peak inflow of 95.16 m3/s and a peak outflow of 49.08 m3/s. The proposed spillway depth of 1000 mm
ensures the PMF is passed without overtopping of the TSF embankment.
Upstream cut-off drain
The catchment area upstream of the Beneficiation and Hydromet TSF is limited by the topography of the local area and equates to a total of 41 ha, this was then split equally between
the two TSFs. The sizing of the drain has been developed to meet the requirements of 1:100 AEP rainfall event using mannings equations for open channels. The parameters used in the development of the drain size can be found below.
Table 9-2 Cut-off drain design parameters
Parameter Value
Area 3 m
Perimeter 4.8 m
Slope 1:500 m
Mannings n 0.025
The drain design allows for flow from each sub-catchment to flow in separate directions
minimising the size of the required drain. Further details on the design of the external
diversion drain can be found in the Pre-Construction Design Drawings in Appendix A.
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9.3 Water balance
A basic spreadsheet water balance model (WBM) was developed by GHD to assess the storage
behaviour and test the capacity of the Hydromet TSF for rainfall and tailings storage. The model will be used as a preliminary check and may be used as a basis for a more detailed version in GoldSIM in the future.
9.3.1 Input data
Hydromet TSF
The physical parameters relating to the Hydromet TSF were based on the current design and are outlined in Table 9-3.
Table 9-3 Hydromet TSF data
Input Values
Maximum Operating Level 339.35 m
Spillway Level 340.5 m
Full Supply Volume ~ 1900 ML
Data relating to the volumes and flow rates of tailings material and bleed water entering the Hydromet TSF appear in Table 9-4.
Table 9-4 Tailings material and bleed water data
Input Values
Annual Production Solids 72,000 tonnes
Flow of Tailings Solids 62,500 m3/day
Flow of Tailings Water Retained Water 0.3 ML/day Free water 1.2 ML/day
Catchment area
There is no external catchment reporting to the Hydromet TSF due to the upstream diversion
drain, as such, the catchment area for the Hydromet TSF is 36.2 hectares.
Climate data
Climate data, including rainfall and evaporation were used for the development of the WBM. The details and sources of the data are outlined in Table 9-5.
Table 9-5 Climate input data
Climate Data Source of Data
Historical Rainfall Data SILO Data drill (Lat -23.95, Long: 116.30) – QLD Government
Historical Evaporation Data SILO Data drill (Lat -23.95, Long: 116.30) – QLD Government
9.3.2 Assumptions
The following assumptions were made in the development of the WBM:
No external catchments report to the Hydromet TSF
All spill from the Hydromet TSF reports to the Beneficiation TSF
The available water shall be evaporated from the Hydromet TSF including free bleed water
from the deposited tailings and rainfall
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The Hydromet TSF was assumed to be empty at the start of the WBM (elevation 331.5 m)
No seepage losses occurred from the Hydromet TSF due to lining
9.3.3 Methodology
Scenario modelling
The scenario tested in the WBM simulates the current plant operational settings to assess the
viability and likely performance of the Hydromet TSF over a 10 year operational mine life. The
scenario was run for three rainfall scenarios, namely, 20 percentile rainfall, 50 percentile rainfall
and 80 percentile rainfall.
Model settings
The settings and corresponding parameters used in the water balance model for the Hydromet
TSF are detailed in Table 9-6.
Table 9-6 Simulation settings
Settings Parameter
Time Step Monthly
Data Range 20 percentile rainfall: 01/07/1889 to 30/06/1906
50 percentile rainfall: 01/07/1938 to 30/06/1948
80 percentile rainfall: 01/07/2009 – 31/12/2018/, to 01/01/1889 – 30/06/1889
Number of Simulation Years 10 Years
Hydromet TSF Initial Water Level 331.5 m
Methodology
The following steps were undertaken in order to model the water balance across the Hydromet
TSF:
20, 50, 80 percentile rainfall scenarios were determined across a 10 year period with
monthly time steps.
– The 20th percentile 10-year rainfall is the volume corresponding at which only 20% of
the record is lower.
– To find a 20th percentile rainfall volume, the entire rainfall record was grouped in
windows of 10 years starting at 1 Jul 1889 to 30 Jun 1898, continuing with 1 Jul 1890
to 30 Jun
– 1899, “wrapping around” at 1 July 2018 to 30 Jun 1897, etc.
– The 10-year window sums are ranked and solved for 20% higher than the lowest
rainfall sum.
– The same procedure is done for the other percentiles.
Monthly average evaporation was determined based on SILO data from 1889 to 2019.
The Hydromet TSF volume was calculated for each time step using the following equation:
– Volume (ML) = P – E+ QT
Whereby:
– P = Precipitation
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– E = Evaporation
– QT = Flow of tailings solids, free water and retained water
9.3.4 Model Results
The overall inventory of the Hydromet TSF appears in Figure 9-5.
Figure 9-5 Overall hydromet TSF inventory
From the water balance analysis it was found that the storage volume for the Hydromet TSF could support the total volume of tailing solids, free water and retained water for a 20, 50 and 80 percentile rainfall over a 10 year period, starting empty.
A detailed whole site GoldSim water balance will be undertaken during detailed design to confirm the site requirements and confirm the findings of the preliminary water balance.
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9.4 Seepage analysis
9.4.1 Methodology
A concept level 2-D seepage analysis using the finite element software, Rocscience Slide, was
carried out to assess the potential for seepage development from the refined TSF arrangement. Only the Beneficiation TSF was considered in the analysis. The Hydromet TSF design features a geocomposite liner system that ensures very small rates of seepage, hence negating the need
for seepage modelling at this stage.
The seepage modelling completed by GHD was carried out to supplement previous seepage modelling presented in ATCW 2019. For the originally proposed arrangement (refer Section 3),
ATCW found that “the presence of confined water pressure in the aquifer below approximately
50 m depth and the presence of a very low permeability, unsaturated granite rock mass above this depth, the likelihood of significant downward seepage of water contained in saturated, very low permeability tailings stored at the ground surface is considered very low”. Seepage modelling by ATCW was limited to considering the Return Water Pond (RWP) and TSF2 since these were considered to have higher seepage potential relative to the other TSFs.
Key changes between the previous concept design presented in ATCW 2019 and the refined TSF arrangement is that both TSF2 and the RWP have been eliminated from the design which significantly reduces the risk of seepage related impacts.
Seepage analysis completed by GHD for the Beneficiation TSF involved developing an idealised cross-section through the TSF with a hydrogeological setting similar to that presented by ATCW 2019 (see Section 2.6) but with sensitivity analysis on layer thickness and hydraulic
permeability to assess the effects of varying conditions.
A transient model was established to estimate the rates of seepage into the foundation due to development of a pond on the Beneficiation TSF and also assessing the benefit of developing a
layer of low permeability tailings below the pond. The fate of seepage with time (0 – 1000 years) within the foundation was then assessed for the various model runs.
The seepage analysis considered a range of permeability values listed in Table 9-7 based on
ATCW inferred values and site investigation works.
Table 9-7 Model hydraulic conductivity values
Material Average ksat (m/s) Sensitivity model ksat (m/s)
Beneficiation Tailings 1 x 10-8
Zone 1 Clay Core 1 x 10-9
Zone 3A Fill Material 1 x 10-8
Sandy Clay Foundation 1 x 10-7
HW / MW Granite 1 x 10-7 1 x 10-6
SW / FR Granite 1 x 10-8 5 x 10-8
Fractured SW / FR Granite Aquifer 1 x 10-6
9.4.2 Results
The results of the seepage analysis shown in Appendix D, illustrates that the seepage expected over the life of the facility is expected to remain within the TSF footprint with the majority of the ponding expected in the highly weathered to moderately weathered granite.
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The vertical seepage through the highly weathered to moderately weathered granite is illustrated below in Figure 9-6 using the flux generated in the seepage modelling. Importantly,
the conceptual modelling indicates that seepage flux exiting the TSF footprint is negligible.
Figure 9-6 HW/MW vertical seepage rates
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9.5 Stability analysis
This Section presents the results of preliminary stability analysis to support the proposed design
of the TSF embankments.
In general the proposed embankment geometry and zoning provides geotechnically stable embankments in accordance with ANCOLD requirements. The design conservatively assumes
staged embankment raising using downstream construction methods.
Geotechnical investigations indicate foundation conditions across the TSF area comprise dense superficial soils and weathered rock at shallow depth. Any low strength or potentially liquefiable
soils will be stripped from the foundation prior to embankment construction.
9.5.1 Approach and methodology
A preliminary geotechnical stability analysis has been completed for the maximum (highest) section of the Beneficiation TSF embankment at its ultimate height as shown in Figure 9-7. This
is considered the critical section for all proposed TSF embankments.
The embankment was modelled with the Slope/W software package to perform Limit Equilibrium slope stability analysis. Bishop’s Simplified Method was adopted in calculating the factor of
safety values against sliding.
Figure 9-7 Stability model section
9.5.2 Load cases and factors of safety
Load cases considered for stability analysis are listed in Table 9-8. The ANCOLD “Guidelines on Tailings Dam Design, Construction, Operation and Closure” (ANCOLD 2012) state that there are no “rules” for acceptable factors of safety. However, they suggest the recommended Factors
of Safety (FoS) as shown in Table 9-8 which have been adopted for this preliminary analysis.
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Table 9-8 Stability analysis FOS acceptance criteria
Condition Minimum Recommended
FoS
Target Minimum FoS
Long term drained conditions 1.5 1.5
For short term undrained conditions (potential loss of containment)
1.5 1.5
For short term undrained conditions (no potential loss of containment)
1.3 1.3
Given the absence of any potentially liquefiable soils within the embankment and foundation as
well as the proposed use of downstream construction methods for raising of the TSF, a post- seismic slope stability case is not considered critical and has been excluded from the preliminary analysis. Seismic assessment based on simplified deformation analysis is
subsequently presented in Section 9.6.
9.5.3 Soil and rock strength parameters
The parameters adopted for the constructed embankments and deposited tailings are based on laboratory testing and are presented in Table 9-9.
Table 9-9 Parameters used for stability analyses
Material Unit Weight
Undrained Effective
(Drained)
kN/m3 c (kPa) () Su c (kPa) ()
Zone 1 Clay 19 100 0 10 20
Zone 3A Selected general fill
21 0 35 0 35
Tailings 0.3 See Note 1 See Note 1
Clayey sand (foundation)
19 80 0 0 20
EW/HW Granite (foundation)
22 13000 35 500 38
SW Granite (foundation)
22 20000 43 500 43
Fresh Granite (foundation)
22 23000 46 500 46
Note 1: Undrained tailings properties were adopted for the drained analysis conservatively assuming that the tailings are contractive and likely to generate significant pore pressures on shearing. The use of drained parameters in stability analyses for contractive tailings is not appropriate as the pore pressure state along the failure surface is unknown.
9.5.4 Model pore pressure
For all analyses, it was assumed that decant water is able to pond against the perimeter embankment resulting in a phreatic surface developing through the embankment. In practice,
this is not allowed to occur and is therefore a very conservative assumption used to allow a simplified but conservative preliminary analysis. The modelled phreatic surface is presented in the model outputs within Appendix E.
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9.5.5 Analyses results
A summary of the minimum Factor of Safety (FoS) achieved for each load condition is provided in Table 9-10. For the proposed embankment design, it can be seen that the minimum target
Factor of Safety is achieved in all cases. Figures showing the critical analysis outputs are given in Appendix E.
Table 9-10 Results of stability analysis
Loading Conditions Calculated FOS Target Minimum FOS
Short term undrained (no loss of containment), Downstream
1.9 1.3
Short term undrained (no loss of containment), Upstream
2.2 1.3
Long term, Undrained 1.9 1.5
Long term, Drained 1.9 1.5
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9.6 Seismic assessment
9.6.1 Seismic risk
The risk posed to the TSF embankments from rare or extreme seismic events is considered to
be Low due to:
The relatively low seismicity of the site
The batter slopes achieve factors of safety above 1.5 for static stability
The embankment and foundations soils are not prone to seismic liquefaction
Based on the above factors, a seismic assessment was limited to simplified deformation
analysis. Two empirical analysis methods have been used including the Swaisgood Method and
Pells and Fell Method as described below. These are simplified screening methods that are
suitable for pre-construction design to confirm that excessive deformation and damage to the
embankment will not occur following an extreme earthquake.
9.6.2 Deformation analysis
ATCW 2019 presented the results of a simplified empirical method using Swaisgood (2003) to
assess the likely magnitude of crest settlement under seismic loading. This previous
assessment is still valid for the current proposed design (i.e. similar embankment and
foundation characteristics). ATCW predicted a maximum crest settlement of 90 mm for the
1:10,000 MCE. This magnitude of embankment settlement is considered acceptable and well
within the freeboard allowance for the TSF. Additionally, when assessed according to the Pells
and Fell (2003) method a “Minor” damage class is expected with associated cracking and
settlement unlikely to result in risk of breach and loss of containment.
Figure 9-8 Relative crest settlement versus peak ground acceleration (ATCW, 2019)
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9.7 Hydromet TSF ammonia gas air emissions study
To inform the pre-construction design of the Hydromet TSF based on combining of the
Hydromet waste streams, Hastings advised GHD of the need to consider the potential health
and safety risks associated with potential for ammonia gas evolving at the TSF.
In April 2019, Hastings provided GHD with a worst case scenario, whereby the Hydromet TSF
receives a tailings stream at 76 t/h containing approximately 0.04 g/L of ammonium bicarbonate
and 6.28 g/L of ammonium hydroxide solution. Based on this “worst case scenario” condition,
GHD completed modelling to assess the potential evolution of ammonia gas (NH3) from the
proposed TSF. The results of this modelling were presented in a GHD Technical Memorandum,
15th April 2019 (refer Appendix I), that included predictions of daily ammonia gas generation
under a range of pH conditions including a worst case condition with an elevated pH of 11.3.
The estimated daily ammonia gas generation for this “worst case scenario” was estimated at
5,300 kg/day NH3.
Hastings subsequently engaged consultants ERM to undertake an air quality modelling
assessment of ammonia emissions from the Hydromet TSF. The ERM report is attached as
Appendix I. The model assessed the emission rate for ammonia under the “worst-case
scenario” described above. Ground level concentrations were evaluated at numerous onsite
and offsite receptor locations. These concentrations were then compared against Ambient and
OHS assessment criteria for NH3. ERM provided the following summary of observations from
their modelling:
No exceedances of air quality criteria were predicted at the identified offsite sensitivereceptors.
One exceedance (25.75 mg/m3) of the 15-min OHS criteria was predicted at an onsite
receptor (TSF receptor 1) located within 250 m from the centre of the source (Figure 4-1).This exceedance occurred under worst-case conditions. The next worst case scenariopredicted a concentration of 12.89 mg/m3 at this same receptor. This concentration is well
within the criteria (50% of the criteria).
In summary, the modelling results indicate that the maximum concentration is of lowlikelihood to occur and dependent on concurrence of worst case emission rate and worst
case dispersion conditions (i.e., prevalence of calm conditions, transition from stable tounstable meteorological conditions, and winds blowing towards this receptor).
Subsequent to completion of the above respective GHD and ERM studies, Hastings advised of
further refinements to the plant design which suggested a revised set of chemistry in offgas absorbing and dual alkali caustic regeneration. Mass Balance assumptions were updated accordingly with a key change being a significant lowering of pH under the worst case scenario
from pH 11.3 (basis of above studies) to below pH 9. This change to the “worst case scenario” is significant, since the amount of ammonia gas generation is proportional to the pH. The reduced pH to below 9 will significantly reduce the generation of NH3 under the worst case
scenario, as is demonstrated in Figure 9-9 below (extract from GHD Technical Memorandum).
Based on the above updates, there is assurance that the modelling completed by GHD and ERM is very conservative and hence the risks associated with ammonia gas evolution from the
Hydromet TSF are suitably low and manageable.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 70
Figure 9-9 Ammonia/ammonium concentration vs pH (Richard, 1996)
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 71
10. Operations, maintenance and surveillance 10.1 Observational approach
In accordance with ANCOLD 2012, the design and management of the TSF shall utilise the
observational approach. The observational approach allows the TSF to be optimised over time
as monitoring information becomes available and the design and construction methodologies
evolve. The observational approach allows any changes that might occur during the life of the
TSF to be accommodated whilst meeting the design criteria and objectives over the entire life of
the TSF.
The key risks that could result in design and operation modifications during commissioning and
operation of the project are:
Life of mine and tailings production rate
Physical properties of the tailing including solids content and rheology
Geochemical properties of the materials
Variation in geological or hydrogeological conditions across the site
Variations in geotechnical properties of embankment materials following borrow pit area
investigations
Further studies and investigations being carried out as part of Detailed Design will assist in
mitigating the risks through greater understanding of the TSF areas.
Critical Operating Parameters (COPs) should be developed for the TSF against which the
performance of the TSF can be evaluated. The indicators address key functional, dam safety
and environmental requirements. The TSF Operating, Maintenance and Surveillance (OMS)
manual is regularly updated to reflect the COP’s and incorporate Trigger Action Response Plans
(TARPs) to ensure that intervention occurs well in advance of nearing any unsafe trigger event.
10.2 Monitoring and surveillance
ANCOLD (2003) provides guidance on the surveillance requirements and frequency for dams
based on their Consequence Category. Regular inspections and monitoring of instrumentation,
by suitably trained operators, is critical in ensuring structural integrity is maintained, and any
indications of failure are identified early and acted on appropriately. Instrumentation is also
important in monitoring the management of tailings against design assumptions, to determine if
any design changes are required during operations, or for closure.
The recommended inspection and monitoring types and frequencies are presented in Table
10-1 and Table 10-2.
Table 10-1 TSF inspection types and frequency
Inspection Type Recommended Frequency (ANCOLD, 2003)
High C
Routine Visual Daily to Tri-Weekly
Intermediate Annual
Comprehensive On Commissioning then 5 Yearly
Special As Required
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 72
Table 10-2 TSF monitoring types and frequency
Monitoring Type Recommended Frequency (ANCOLD, 2003)
High C
Rainfall Daily to Tri-Weekly
Storage Level Daily to Tri-Weekly
Seepage Daily to Tri-Weekly
Chemical Analysis of Seepage
ANCOLD recommend this be considered. The environmental monitoring plan for the site incorporates this requirement.
Pore Pressure Monthly to 6-Monthly
Surface movement 2 Yearly
The following instrumentation / monitoring is recommended at the site:
Rainfall gauge
V-notch weirs for environmental flow monitoring and seepage (if observed)
Vibrating wire piezometers (VWPs) for pore pressure monitoring
Settlement markers on embankments for movement monitoring
Regular tailings beach surveys for density reconciliation and comparing actual beach
development against design assumptions
Level gauge boards and / or automated level sensors for monitoring water levels
Monitor slurry density at the plant to compare against design assumptions
Monitoring of beach saturation via either routine sampling/testing or instrumentation
10.2.1 Instrumentation
This section outlines likely instrumentation that would be required, for monitoring safety and
performance of the storages.
Groundwater monitoring
A series of groundwater monitoring bores are proposed around the TSFs, to monitor
groundwater level and quality. These bores will be monitored up to 12 months prior to
commencement of deposition of tailings to provide baseline data for the project and then
quarterly throughout the life of the project.
To intercept groundwater in the confined aquifer, the bores will need to be approximately 70 m
deep with a nested bore approximately 20 m deep to confirm upward seepage from the
confined aquifer is not taking place.
The deeper bores should be constructed in accordance with the Minimum Construction
Requirements for Water Bores in Australia and screened across the first water strike
encountered. Gravel pack should be installed to at least one metre above the top of the screen
followed by a bentonite seal not less than two metres thick. The remainder of the well annulus
should be cement grouted to the surface.
A number of Vibrating Wire Piezometers (VWP) are also proposed to be installed under the
embankments to identify seepage development within the underlying foundation.
The proposed monitoring bore and VWP layout is presented in Drawing DWG-C010.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 73
Movement monitoring
Surface movement monuments are recommended on the crest of the storages, to monitor
potential movement / settlement over the life of the facility, particularly following significant
rainfall events, spill events, and earthquake events.
Additional monuments may be installed on areas where ground conditions would lead to
increased risk of differential settlement.
Permanent survey pillars will need to be located on natural ground at strategic locations outside
the embankment to allow routine movement monitoring of the embankments.
10.3 Operation, maintenance and surveillance manual
An Operations Maintenance and Surveillance (OMS) Manual (operating manual) should be
prepared as part of the TSF Detailed Design. The principal objective of this manual is to provide
a documented operation procedure to assist in the safe and efficient storage of tailings and
water management in the TSF cells.
The OMS manual shall be prepared to meet the minimum regulatory requirements (ANCOLD,
2003 and DME, 1998) and include:
Roles and responsibilities
Design intent
Regular operations and inspections
Water and tailings management procedures
Operational requirements for mechanical equipment and instrumentation
Maintenance schedules and procedures
Surveillance requirements
Examples of potential damages and associated repair works
Definition of Critical Operating Parameters and associated Trigger Action Response Plans
The OMS manual should outline key monitoring activities which will include:
Routine reconciliation of tailings discharge tonnage and solids concentration
Tailings beach scans (nominally quarterly) to provide up to date pond storage
characteristics
Routine monitoring of tailings beach levels
Routine monitoring of pond water levels and process plant return water rates
Routine monitoring of groundwater level fluctuations
Routine assessment of groundwater and decant pond water quality
Underdrainage system return rates and volume
Annual field evaluation of tailings beach density
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 74
10.4 Dam safety emergency plan
ANCOLD (2003) states a Dam Safety Emergency Plan (DSEP) be prepared where any
persons, infrastructure or environmental values could be at risk if the dam were to fail. A DSEP
is therefore recommended for both TSFs.
The DSEP should include (but not be limited to) the following:
Critical contact details
Trigger Action Response Plans (TARPs)
Procedures in specific failure events
Emergency muster points
Dam break inundation maps
Training of site personnel, whom will be responsible for dam inspections, operation and
management, is recommended; this would include familiarisation with the OMS and DSEP.
10.5 Annual audits
Fundamental to the design of the TSF is the proposed Observational Approach and ongoing
Dam Safety Program as described throughout this document, by which there is a means of
monitoring and measuring the safe and environmentally responsible management of the TSF
throughout the full TSF life cycle. Annual Operational Reviews/Audits aim to:
Evaluate the implementation and effectiveness of the tailings management system
Reduce risk, and to drive continuous improvement
Provide assurance to company and regulatory stakeholders that the TSF is being
effectively managed in conformance with design, operational and management
commitments
Once indicators and targets are set they must be routinely monitored and reviewed to identify
any changes and areas for improvement. It is proposed that routine annual reviews are
conducted to identify trends in the data that might cause concern as early as possible. It is
essential to react to these concerns well before they impact on the integrity and performance of
the structure or the receiving environment and become increasing difficult to resolve. As
modification effort could span several years to reduce its impact on the overall operation,
addressing a major problem at a later stage might be operationally difficult, expensive, and
could even be impractical. The observational method provides the ability to address concerns
through a proactive rather than reactive approach.
Indicators and targets should be reviewed and if necessary updated during the reviews to
ensure they remain a valid and useful way of evaluating TSF performance.
10.6 TSF operator training
Effective operations and maintenance of the TSF is dependent on the staff achieving an
acceptable level of competency. To enable staff to perform their duties to this standard, staff
need to undergo training specifically addressing the operation and maintenance of tailings
facilities, which should include:
Occupational health and safety responsibilities
Operations and maintenance of the dams and outlet works components
Familiarity with the COPs and TARPs
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 75
Dam surveillance
Emergency procedures
10.7 Temporary mining and plant shutdown provisions
In the event of a temporary mining and plant shut down, there may be an extended period
without tailings deposition into the Beneficiation and Hydromet TSFs. As discussed in Section
5.3, all tailings are Non-Acid Forming and hence there is a very low risk associated with AMD
development on the tailings beaches. Normal TSF operations, surveillance and maintenance
activities would need to continue for these shutdown periods however the lack of tailings
discharge will require special provisions to control the generation of dust. The necessary
mitigation measures would depend on the period of shut-down however may include measures
such as:
Irrigation of tailings beaches with mine make-up water;
Application of dust suppression chemicals using a LGP water cart or by aerial spraying;
Temporary capping of tailings beaches with locally won earthfill.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 76
11. References ADWG 2011. National Water Quality Management Strategy. Australian Drinking Water
Guidelines 6. Version 3.4.
AMIRA 2002. Project P387A Prediction & Kinetic Control of Acid Mine Drainage - ARD Test
Handbook. AMIRA International Limited, Melbourne.
ANCOLD 1998. Guidelines for Design of Dams for Earthquake, Australian National Committee
on Large Dams, August 1998.
ANCOLD 2000. Guidelines on Selection of Acceptable Flood Capacity for Dams, Australian
National Committee on Large Dams, March 2000.
ANCOLD 2003a. Guidelines on Dam Safety Management, Australian National Committee on
Large Dams, August 2003.
ANCOLD 2012. Guidelines on Tailings Dams Planning, Construction, Operation and Closure,
Australian National Committee on Large Dams, May 2012.
ANCOLD 2012. Guidelines on the Consequence Categories for Dams, Australian National
Committee on Large Dams, October 2012.
ANSTO. 2017. Technical Memorandum: AM/TM2017_08_04.
ANZECC & ARMCANZ. 2000. Australian and New Zealand Guidelines for Fresh and Marine
Water Quality. Australian and New Zealand Environment and Conservation Council (ANZECC)
and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ).
ATC Williams (ATCW). 2019, Yangibana Rare Earths Project, Tailings Storage Facilities Design
Report, Document No.: Ygb-30-000-Eng-Pro-Rep-0001, 30/01/2019.
BOM 2010. Australian climate influences, Bureau of Meteorology. Available from:
http://www.bom.gov.au/climate/about/
Commonwealth Department of Industry. 2016. Preventing Acid and Metalliferous Drainage.
Manual in the Leading Practice Sustainable Development Program for the Mining Industry
series. Department of Industry, Tourism and Resources (DITR), Canberra. September 2016.
DER, Background paper on the use of leaching tests for assessing the disposal and re-use of
waste-derived materials, Government of Western Australia, Department of Environmental
Regulation, July 2015.
Desmond, A., Kendrick, P., & Chant, A. 2001. "Gascoyne 3 (GAS3 - Augustus subregion)," in A
Biodiversity Audit of Western Australia's 53 Biogeographical Subregions in 2002, N. McKenzie,
J. May, & S. McKenna eds., Department of Conservation and Land Management, pp. 240-251.
DFAT 2016. Preventing Acid and Metalliferous Drainage. Manual in the Leading Practice
Sustainable Development Program for the Mining Industry series. Canberra Department of
Foreign Affairs and Trade, (DFAT).
DME 1998. Guidelines on the Development of and Operating Manual for Tailings Storage,
Department of Minerals and Energy Western Australia, October 1998.
DMP & EPA 2015. Guidelines for Preparing Mine Closure Plans, Department of Mines and
Petroleum and Environmental Protection Agency Western Australia, May 2015.
DMP 2015. Guide to the Preparation of a Design Report for Tailings Storage Facilities (TSFs),
Department of Mines and Petroleum Western Australia, August 2015.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 77
DMP 2010. Managing Naturally Occuring Radioactive Material (NORM) in Mining and Mineral
Processing – Guideline. NORM – 4.2. Management of Daioactive Waste: Resource Safety,
Department of Mines and Petroleum Western Australia, 21 pp, February 2010.
DMP 2013. Tailings Storage Facilities in Western Australia – Code of Practice, Resources
Safety and Environmental Divisions, Department of Mines and Petroleum Western Australia, 13
pp, 2013.
DOW 2013. Water Quality Protection Note 27 – Liners for Containing Pollutants, Using
Engineered Soils, Department of Water Western Australia, August 2013.
ERM 2019. TSF Ammonia Emissions. Environmental Resources Management Australia Pty Ltd,
May 2019.
Ewais, A.M.R., and R.K. Rowe. 2014. “Degradation of 2.4 mm-HDPE geomembrane with high
residual HP-OIT,” in 10th International Conference on Geosynthetics (10th ICG), Sept. 21-25,
2014. Berlin, Germany: International Geosynthetics Society, 2014.
GHD 2019. Technical Memorandum – Yangibanna TSF Ammonia Evolution Modelling, April
2019.
GRM 2017. DFS Study – Stage 1 Hydrogeological Assessment, Yangibana Rare Earths
Project. Report Ref J160014R01, Groundwater Resource Management, 2017.
K. Tian, C. Benson, J. Tinjum. 2017. “Chemical characteristics of leachate in low-level
radioactive waste disposal facilities.” Journal of Hazardous, Toxic, and Radioactive Waste 2017.
Kendrick, P. 2002. "Gascoyne 1 (GAS1 - Ashburton subregion)," in A Biodiversity Audit of
Western Australia's 53 Biogeographic Subregions in 2002, Department of Conservation and
Land Management, Perth, pp. 224-232.
National Environment Protection (Assessment of Site Contamination) Measure 1999 as
amended 2013. Schedule B1; Investigation Levels For Soil and Groundwater.
Paul, M. 2016. Analysis of Selenium in Difficult Samples. Thermo Fisher Scientific GmbH, Im
Steingrund 4-6, Dreiech, Germany, pp.1-3.
Peel, M.C., Finlayson, B.L., & McMahon, T.A. 2007. Updated world map of the Köppen-Geiger
climate classification. Hydrology and Earth System Sciences, vol. 11, pp. 1633-1644
Rentz, A.K., R.W.I. Brachman, W.A. Take and R.K. Rowe. 2017. “Comparison of Wrinkles in
White and Black HDPE Geomembranes.” Journal of Geotechnical and Geoenvironmental
Engineering. 143(8)
Rowe, R. K., Chappel, M. J., Brachman, R. W. I., and Take, W. A. 2012. “Field monitoring of
geomembrane wrinkles at a composite liner test site.” Canadian Geotechnical Journal, 49,
1196– 1211
Trajectory 2017. Landform Evolution Study. Hastings Technology Metals Limited Yangibana
Rare Earths Project. Trajectory.
Trajectory and GCA 2017. Tailings Characterisation Report. Hastings Technology Metals
Limited Yangibana Rare Earths Project. Trajectory and Graeme Campbell & Associates PTY
LTD.
Trajectory and GCA 2018. Tailings Leach Study Report. Hastings Technology Metals Limited
Yangibana Rare Earths Project. Trajectory and Graeme Campbell & Associates PTY LTD.
US-EPA. 2017, “Validated Test Method 1313: Liquid-Solid Partitioning as a Function of Extract
pH Using a Parallel Batch Extraction Procedure” United States Environmental Protection
Agency, pp. 3.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 78
WADEC. 2009. Landfill Waste Classification and Waste Definitions 1996 (As amended
December 2009). Perth: Western Australia Department of Environment and Conservation.
Refer also to the Basis of Design documentation listed in Table 4-1 and Table 4-2 of this report.
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134
Appendices
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 |
Appendix ADesign Drawings
GHD | Report for Hastings Technology Metals Limited- Yangibana TSF Design Development, 3219134
Appendix BTailings Test Results, Geotechnical
Column Sedimentation Test - Results SYD1900567.3
Client: Hastings Technology Metals Ltd Job No: 3219134Project: Yangibana GHD Sample No: SYD19-0110-01
Location: Option Study Client ID: Pilot Plant Combined Beneficiation Tailings
Settlement data
Time (hrs)Slurry Height
(mm)Volume (%)
0.01 306 100 Test Data0.03 306 1000.06 306 100 Total mass of tailings+cylinder (g): 19390 Date Commenced: 20/03/20190.13 306 100 Mass cylinder (g): 7551 Date Completed:0.25 306 100 Mass tailings (g): 11839 Tested by: ZK0.50 305 100 Initial Volume tailings (cm³): 8675.98 Checked By:1.00 304 99 Volume of tailings at NC (cm3): 5812.342.00 301 98 Final Volume of tailings (cm3): 4947.583.00 299 984.00 295 96 ESTIMATED NORMALLY ESTIMATED FINAL UNDRAINED
5.00 293 96 INITIAL TEST CONDITIONS CONSOLIDATED TEST CONDITIONS TEST CONDITIONS
6.00 290 95 Solids: 40 Solids: 75 Solids: 867.00 288 94 Saturation: 100% Saturation: 100% Saturation: 100%8.00 285.5 93 eo: 4.643 ef: 2.780 ef: 2.21823.50 261 85 sat: 1.365 sat: 2.037 sat: 2.39330.33 253 83 dry: 0.546 dry: 0.815 dry: 0.95748.00 236 77 w: 150% w: 33% w: 16%56.00 230 75
120.00 208 68143.00 205 67 end primary167.25 203.5 67216.00 202 66288.25 201 66
290 200 65292.00 199 65290.43 198 65292.50 195 64294.50 193 63311.50 184 60337.00 179.5 59 TEST CONDITIONS362.75 178 58 Cylinder Diameter (mm): 190485.00 174.5 57 Initial Ht of Test (mm): 306.0
Final height of Sediment (mm): 201.0Water Type: As received
Apparent Particle Density: 3.08Initial Mass of Tailings (g): 11839
Initial Moisture content calculated from densities (%): 150NC Moisture content calculated from densities (%): 33
Final Moisture content calculated from densities (%): 16
25
50
75
100
125
0.0 0.1 1.0 10.0 100.0 1000.0
Slu
rry
volu
me
%
Time (hrs)
Undrained settlement
Drained settlement
GHD GeotechnicsUnit 5, 43 Herbert St Artarmon NSWp: (02) 9462 4860f: (02) 9462 4710
Column Sedimentation Test Permeability Stage Report No: SYD1702548
Client: Hastings Technology Metals Ltd Job No : Sample No: SYD19-0110-01
Client ID:
Project: Yangibana Report No : SYD1900567.3
Area m2 0.0284Date & time Time Elapsed
Time (hrs)
1 Soil height (mm)
1 Water Height (mm)
Hydraulic Gradient
Flow rate mls / hr
2 k (m/s) from Water Height
Change
Collected Seepage
(mls)
Seepage Flow Rate
(m 3 /s)
2 k (m/s) from Collected Seepage
Comment
1/04/2019 1:57:00 AM 0 201 306 1.52 01/04/2019 4:30:00 PM 4.55 193 292 1.51 59.8 5.6E-07 272 1.7E-08 3.9E-07 Draining2/04/2019 9:30:00 AM 21.55 184 281 1.53 18.2 1.2E-07 309.8 5.1E-09 1.2E-07 Draining3/04/2019 11:00am 47.05 179.5 269 1.50 12.5 8.6E-08 318.8 3.5E-09 8.1E-08 Draining4/04/2019 12:45:00 PM 72.8 178 259 1.46 11.5 7.3E-08 295.7 3.2E-09 7.6E-08 Draining5/04/2019 3:00:00 PM 99.05 177 249 1.41 10.9 7.4E-08 284.9 3.0E-09 7.4E-08 refill to 291
99.05 177 291 1.41 10.9 7.4E-08 3.0E-09 7.4E-088/04/2019 12:40:00 PM 168.72 175 263.5 1.51 11.9 7.5E-08 826.2 3.3E-09 8.0E-089/04/2019 3:00:00 PM 195.05 174.5 253 1.45 11.3 7.5E-08 296.9 3.1E-09 7.5E-08
3 k= 7.5E-08
Notes Shearvane tests at end of test NotesVane size: 50mm (readable to 0.07 kPa) 1. From base of sample
Upper Test Lower Test 2. Between consecutive recordsPeak (kPa): 3. From change in water height
Residual (kPa):
3219134.00
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0 50 100 150 200 250
mls per hour
Time hrs
Flow rate mls / hr
1.0E‐09
1.1E‐08
2.1E‐08
3.1E‐08
4.1E‐08
5.1E‐08
6.1E‐08
7.1E‐08
8.1E‐08
9.1E‐08
0 50 100 150 200 250
m/s
time hrs
Permeability m/s
Seepage Flow Rate (m3/s)
2k (m/s) from Collected Seepage
GHD GeotechnicsUnit 5 / 43 Herbert St Artarmon NSWp: (02) 9462 4700f: (02) 9462 4710
Column Sedimentation Test - Report Report No: SYD1900567.2
Client: Hastings Technology Metals Ltd Job No: 3219134Project: Yangibana GHD Sample No: SYD19-0110-02
Location: Option Study Client ID: Pilot Plant
Settlement data
Time (hrs)Slurry Height
(mm)Volume (%) SAMPLE AERATED WHEN MIXED, AIR REMOVED INSITU & SAMPLE PLUNGED TO REMIX
20/03/2019 0.01 295 100 Test Data0.03 295 1000.06 295 100 Total mass of tailings+cylinder (g): 23842 Date Commenced: 20/03/20190.13 295 100 Mass cylinder (g): 12717 Date Completed: 10/05/20190.25 295 100 Mass tailings (g): 11125 Tested by: ZK0.50 295 100 Initial Volume tailings (cm³): 8364.10 Checked By: DB1.00 294 100 Volume of tailings at NC (cm3): 6010.812.00 292 99 Final Volume of tailings (cm3): 5089.343.00 291 994.00 290 98 ESTIMATED NORMALLY ESTIMATED FINAL UNDRAINED
5.00 289 98 INITIAL TEST CONDITIONS CONSOLIDATED TEST CONDITIONS TEST CONDITIONS
6.00 286 97 Solids: 37 Solids: 68 Solids: 807.00 284 96 Saturation: 100% Saturation: 100% Saturation: 100%
8.00 283 96 eo: 5.310 ef: 3.534 ef: 2.839
23.50 265 90 sat: 1.330 sat: 1.851 sat: 2.18630.33 259 88 dry: 0.488 dry: 0.679 dry: 0.80248.00 246 83 w: 172% w: 47% w: 24%56.00 241 82120.00 218 74 Shearvane after draining: 1.0 kPa143.00 214.5 73 50mm vane167.25 212 72 end primary216.00 210 71 Moisture content after draining: 56.2%288.25 208.5 71
Drained 290 206.5 70292.00 206 70290.43 204 69292.50 201 68294.50 200 68311.50 190 64337.00 185 63 TEST CONDITIONS362.75 183 62 Cylinder Diameter (mm): 190485.00 179.5 61 Initial Ht of Test (mm): 295.0
Final height of Sediment (mm): 179.5Water Type: As received
Apparent Particle Density: 3.08Initial Mass of Tailings (g): 11125
Initial Moisture content calculated from densities (%): 172NC Moisture content calculated from densities (%): 47
Final Moisture content calculated from densities (%): 24
50
55
60
65
70
75
80
85
90
95
100
105
0.0 0.1 1.0 10.0 100.0 1000.0
Sa
mp
le V
olu
me
(%
)
Time (hrs)
Drained settlement
Undrained settlement
GHD GeotechnicsUnit 5, 43 Herbert St Artarmon NSWp: (02) 9462 4860f: (02) 9462 4710
Column Sedimentation Test Permeability Stage Report No: SYD1702548
Client: Hastings Technology Metals Ltd Job No : Sample No: SYD19-0110-02
Client ID:
Project: Yangibana Report No : SYD1900567.2
Area m2 0.0284Date Time Elapsed Time
(hrs)
1 Soil height (mm)
1 Water Height (mm)
Hydraulic Gradient
Flow rate mls
/ hr
2 k (m/s) from Water Height
Change
Collected Seepage
(mls)
Seepage Flow Rate
(m 3 /s)
2 k (m/s) from Collected Seepage
Comment
1/04/2019 11:57:00 PM 0 208.5 295 1.41 0 Draining1/04/2019 4.55 200 284.5 1.42 67.1 4.5E-07 305.3 1.9E-08 4.6E-07 Draining2/04/2019 21.55 190 273 1.44 15.9 1.3E-07 269.9 4.4E-09 1.1E-07 Draining3/04/2019 47.05 185 262 1.42 11.5 8.4E-08 293.8 3.2E-09 7.9E-08 Draining4/04/2019 72.8 183 253 1.38 10.3 6.9E-08 266.2 2.9E-09 7.2E-08 Draining5/04/2019 99.05 182 244 1.34 9.7 7.0E-08 255.3 2.7E-09 7.0E-08 refill to 286
99.05 182 286 1.34 9.7 2.7E-09 7.0E-088/04/2019 168.72 180 259 1.44 10.5 7.7E-08 729.7 2.9E-09 7.4E-089/04/2019 195.05 179.5 248 1.38 10.1 8.2E-08 265.8 2.8E-09 7.0E-08
3 k= 8.2E-08
Notes Shearvane tests at end of test NotesVane size: 50mm (readable to 0.07 kPa) 1. From base of sample
Upper Test Lower Test 2. Between consecutive recordsPeak (kPa): 1 - 3. From change in water height
Residual (kPa): - -
3219134.00
1.0E‐09
1.1E‐08
2.1E‐08
3.1E‐08
4.1E‐08
5.1E‐08
6.1E‐08
7.1E‐08
8.1E‐08
9.1E‐08
0 50 100 150 200 250
m/s
Time hrs
Permeability m/s
Seepage Flow Rate (m3/s)
2k (m/s) from CollectedSeepage
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
0 50 100 150 200 250
mls per hour
Time hrs
Flowrate mls/hr
GHD GeotechnicsUnit 5 / 43 Herbert St Artarmon NSWp: (02) 9462 4700f: (02) 9462 4710
0 0.00 True
Environmental
CERTIFICATE OF ANALYSISWork Order : Page : 1 of 2ES1909306
:: LaboratoryClient GHD PTY LTD Environmental Division Sydney
: :ContactContact Sarah Gilmour Customer Services ES
:: AddressAddress LEVEL 15, 133 CASTLEREAGH STREET
SYDNEY NSW, AUSTRALIA 2000
277-289 Woodpark Road Smithfield NSW Australia 2164
:Telephone ---- :Telephone +61-2-8784 8555
:Project 3219134 Yangibana TSF Option Study Date Samples Received : 27-Mar-2019 12:50
:Order number Date Analysis Commenced : 28-Mar-2019
:C-O-C number ---- Issue Date : 29-Mar-2019 09:40
Sampler : ----
Site :
Quote number : EN/005/18
1:No. of samples received
1:No. of samples analysed
This report supersedes any previous report(s) with this reference. Results apply to the sample(s) as submitted. This document shall not be reproduced, except in full.
This Certificate of Analysis contains the following information:
l General Comments
l Analytical Results
Additional information pertinent to this report will be found in the following separate attachments: Quality Control Report, QA/QC Compliance Assessment to assist with
Quality Review and Sample Receipt Notification.
SignatoriesThis document has been electronically signed by the authorized signatories below. Electronic signing is carried out in compliance with procedures specified in 21 CFR Part 11.
Signatories Accreditation CategoryPosition
Dian Dao Sydney Inorganics, Smithfield, NSW
R I G H T S O L U T I O N S | R I G H T P A R T N E R
Combined Benefication Tailings Column Test Bleed Water TSS
2 of 2:Page
Work Order :
:Client
ES1909306
3219134 Yangibana TSF Option Study:Project
GHD PTY LTD
General Comments
The analytical procedures used by the Environmental Division have been developed from established internationally recognized procedures such as those published by the USEPA, APHA, AS and NEPM. In house
developed procedures are employed in the absence of documented standards or by client request.
Where moisture determination has been performed, results are reported on a dry weight basis.
Where a reported less than (<) result is higher than the LOR, this may be due to primary sample extract/digestate dilution and/or insufficient sample for analysis.
Where the LOR of a reported result differs from standard LOR, this may be due to high moisture content, insufficient sample (reduced weight employed) or matrix interference.
When sampling time information is not provided by the client, sampling dates are shown without a time component. In these instances, the time component has been assumed by the laboratory for processing
purposes.
Where a result is required to meet compliance limits the associated uncertainty must be considered. Refer to the ALS Contact for details.
CAS Number = CAS registry number from database maintained by Chemical Abstracts Services. The Chemical Abstracts Service is a division of the American Chemical Society.
LOR = Limit of reporting
^ = This result is computed from individual analyte detections at or above the level of reporting
ø = ALS is not NATA accredited for these tests.
~ = Indicates an estimated value.
Key :
Analytical Results
----------------Yangibana DecantClient sample IDSub-Matrix: WATER
(Matrix: WATER)
----------------22-Mar-2019 00:00Client sampling date / time
--------------------------------ES1909306-001UnitLORCAS NumberCompound
Result ---- ---- ---- ----
EA025: Total Suspended Solids dried at 104 ± 2°C
88 ---- ---- ---- ----mg/L1----Suspended Solids (SS)
Yangibana TSF Option StudyLocationSILT: brown (Tailings)Soil Description
Sample DetailsSYD19-0110-01GHD Sample NoSampled By ClientSampled By01/03/2019Date Sampled
Test Results
Standard0.00.0
1.0862.867.7
Syd tap water30
2 E-0912/03/2019
150Result
Moisture Content (%) AS 1289.2.1.1MethodDescription Limits
Date TestedCoef of Permeability (m/sec) AS 1289.6.7.3Mean Stress Level (kPa)Permeant UsedLength (mm)Diameter (mm)Length/Diameter RatioLaboratory Moisture Ratio (%)Laboratory Density Ratio (%)CompactiveEffort
RemouldedMethod of Compaction0.0Surcharge Applied (Kg)10Pressure Applied (Kpa)
6.3Oversize Sieve (mm)0.0Percentage Oversize (%)
25.9Moisture Content (%)22/03/2019Date Tested
Sydney Laboratory Unit 5/43 Herbert StArtarmon NSW 2064email: [email protected]: www.ghd.com.au/ghdgeotechnicsTel: (02) 9462 4860Fax:(02) 9462 4710
Aggregate/Soil Test Report Report No: SYD1900567Issue No: 2
This report replaces all previous issues of report no 'SYD1900567'.Accredited for compliance with ISO / IEC 17025 -Testing
10/05/2019NATA Accredited
Laboratory Number:679 Date of Issue:
THIS DOCUMENT SHALL NOT BE REPRODUCED EXCEPT IN FULL
Client:
Project: 3219134
Hastings Technology Metals LimitedPerth WA 6000167 St George Terrace
Approved Signatory: D.P Brooke (Sydney Laboratory Manager)
Page 1 of 1© 2000-2016 QESTLab by SpectraQEST.comForm No: 18909, Report No: SYD1900567
Moisture and Density Ratio's not applicable.Sample intial dry density = 1.825 t/m³ and MC = 21.9 %Sample final dry density = 1.821 t/m³ and MC = 25.9 %
Comments
Trial Hole: -Depth (m): -Sample No: SYD19-0110-01
Client: Hastings Technology Metals Limited Client Sample No.: -
Project: Yangibana TSF Sample History:Location: Options Study
TEST METHODSParticle size AS1289.3.6.3
OTHER TESTS AS1289.3.1.1 AS1289.3.2.1 AS1289.3.3.1 AS1289.3.4.1 AS1289.3.5.1
GRADINGCu = D60 / D10 = 22.02Cc = D30² / (D10 x D60) = 0.71
PARTICLE DENSITY 3.08 (measured) INDEX PROPERTIES (%)Liquid Limit = 24 Plastic Limit = 21
PRE-TREATMENT HYDROMETER No Plasticity Index = 3 Linear Shrinkage % =4.0
TEST CONDITION Washed sieve with dispersing agent Atterberg Limits (History/Preparation) Oven Dried
GROUP SYMBOL: Liquid Limit (type of test) 4 Point
Linear Shrinkage (mould size) 125 mmSOIL NAME: SILT: brown
REMARKS:
Tested by: AM GHD Pty Ltd Date tested: 27.03.19 Unit 5, 43 Herbert St, Artarmon NSW, 2064 Checked by: GV Tel: (02) 9462 4700 Fax: (02) 9462 4710 Date checked: 10/05/2019 Approved Signatory:
JOB No. 3219134
REPORT No. SYD1900567.1D. Brooke 10/05/2019 Ref: Document F9.1.16 issue 1.2
This laboratory Certificate may not be reproduced except in full unless permission for the publication of anapproved extract has been obtained in writing from GHD Pty Ltd
Laboratory Accreditation Number - 679
Accredited for compliance with ISO/IEC 17025 -Testing
10010010010099
72
52
46
42
3633
26
21
1614
106
AS SIEVE SIZE (mm) 0.07
5
0.15
0.21
2
0.3
0.42
5
0.6
1.18
2.36
4.75
6.7
9.5
13.2
19 26.5
37.5
53 75 200
0
10
20
30
40
50
60
70
80
90
1000
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
PE
RC
EN
TA
GE
RE
TA
INE
D
PE
RC
EN
TA
GE
PA
SS
ING
Medium Coarse Fine
SILT FRACTION SAND FRACTION GRAVEL FRACTION
CL
AY
COBBLES BOULDERS
0.002 0.006 0.02 0.075 0.2 0.6 6 20 63 200
CoarseMediumFine CoarseMediumFine
2.36
PARTICLE SIZE (mm)
SOIL CLASSIFICATION REPORT
Sampled By GHD
0
50
0 50 100
CL
MLOL
CH
MHOH
IP
Liquid limit (WL)
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix CCombined Beneficiation Tailings Test Results, Geochemical
0 0.00 True
Environmental
CERTIFICATE OF ANALYSISWork Order : Page : 1 of 16ES1907149
:Amendment 1:: LaboratoryClient GHD PTY LTD Environmental Division Sydney
: :ContactContact Sarah Gilmour Shirley LeCornu
:: AddressAddress 2 SALAMANCA SQUARE
HOBART TAS, AUSTRALIA 7000
277-289 Woodpark Road Smithfield NSW Australia 2164
:Telephone ---- :Telephone +6138549 9630
:Project 3219134 Date Samples Received : 08-Mar-2019 08:15
:Order number 3219134 Date Analysis Commenced : 11-Mar-2019
:C-O-C number ---- Issue Date : 23-Apr-2019 10:50
Sampler : Narelle Marriott (Hastings)
Site : Hasting's Yangibana Project
Quote number : ME/158/19
14:No. of samples received
14:No. of samples analysed
This report supersedes any previous report(s) with this reference. Results apply to the sample(s) as submitted. This document shall not be reproduced, except in full.
This Certificate of Analysis contains the following information:
l General Comments
l Analytical Results
Additional information pertinent to this report will be found in the following separate attachments: Quality Control Report, QA/QC Compliance Assessment to assist with
Quality Review and Sample Receipt Notification.
SignatoriesThis document has been electronically signed by the authorized signatories below. Electronic signing is carried out in compliance with procedures specified in 21 CFR Part 11.
Signatories Accreditation CategoryPosition
Ankit Joshi Inorganic Chemist Sydney Inorganics, Smithfield, NSW
Ivan Taylor Analyst Sydney Inorganics, Smithfield, NSW
Satishkumar Trivedi Senior Acid Sulfate Soil Chemist Brisbane Acid Sulphate Soils, Stafford, QLD
Wisam Marassa Inorganics Coordinator Sydney Inorganics, Smithfield, NSW
R I G H T S O L U T I O N S | R I G H T P A R T N E R
2 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
General Comments
The analytical procedures used by the Environmental Division have been developed from established internationally recognized procedures such as those published by the USEPA, APHA, AS and NEPM. In house
developed procedures are employed in the absence of documented standards or by client request.
Where moisture determination has been performed, results are reported on a dry weight basis.
Where a reported less than (<) result is higher than the LOR, this may be due to primary sample extract/digestate dilution and/or insufficient sample for analysis.
Where the LOR of a reported result differs from standard LOR, this may be due to high moisture content, insufficient sample (reduced weight employed) or matrix interference.
When sampling time information is not provided by the client, sampling dates are shown without a time component. In these instances, the time component has been assumed by the laboratory for processing
purposes.
Where a result is required to meet compliance limits the associated uncertainty must be considered. Refer to the ALS Contact for details.
CAS Number = CAS registry number from database maintained by Chemical Abstracts Services. The Chemical Abstracts Service is a division of the American Chemical Society.
LOR = Limit of reporting
^ = This result is computed from individual analyte detections at or above the level of reporting
ø = ALS is not NATA accredited for these tests.
~ = Indicates an estimated value.
Key :
ED041G: LOR raised for Sulfate on samples 10 and 12 due to sample matrix.l
EN055: Ionic Balance out of acceptable limits for various samples due to analytes not quantified in this report.l
ASS: EA013 (ANC) Fizz Rating: 0- None; 1- Slight; 2- Moderate; 3- Strong; 4- Very Strong; 5- Lime.l
(ADD METHOD): NATA accreditation does not cover performance of this service.l
EA016: Calculated TDS is determined from Electrical conductivity using a conversion factor of 0.65.l
EA046 ABCC: NATA Acreditation does not cover the performance of this service.l
Sodium Adsorption Ratio (where reported): Where results for Na, Ca or Mg are <LOR, a concentration at half the reported LOR is incorporated into the SAR calculation. This represents a conservative approach
for Na relative to the assumption that <LOR = zero concentration and a conservative approach for Ca & Mg relative to the assumption that <LOR is equivalent to the LOR concentration.
l
3 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T05 - pH 8.0
2018 bene combined
tailings
T04 - pH 9.0
2018 bene combined
tailings
T03 - pH 10.5
2018 bene combined
tailings
T02 - pH 12.0
2018 bene combined
tailings
T01 - pH 13.0
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-006ES1907149-005ES1907149-004ES1907149-003ES1907149-002UnitLORCAS NumberCompound
Result Result Result Result Result
EA005P: pH by PC Titrator
12.8 11.9 10.0 9.09 8.10pH Unit0.01----pH Value
EA010P: Conductivity by PC Titrator
32800 1070 213 259 341µS/cm1----Electrical Conductivity @ 25°C
EA016: Calculated TDS (from Electrical Conductivity)
21300 696 138 168 222mg/L1----Total Dissolved Solids (Calc.)
EA065: Total Hardness as CaCO3
<1 <1 <1 284 36mg/L1----Total Hardness as CaCO3
ED037P: Alkalinity by PC Titrator
6140Hydroxide Alkalinity as CaCO3 103 <1 <1 <1mg/L1DMO-210-001
761Carbonate Alkalinity as CaCO3 340 20 7 <1mg/L13812-32-6
<1Bicarbonate Alkalinity as CaCO3 <1 64 38 42mg/L171-52-3
6900 443 84 45 42mg/L1----Total Alkalinity as CaCO3
ED041G: Sulfate (Turbidimetric) as SO4 2- by DA
4Sulfate as SO4 - Turbidimetric 5 6 <1 <1mg/L114808-79-8
ED045G: Chloride by Discrete Analyser
23Chloride 11 11 <1 <1mg/L116887-00-6
ED093F: Dissolved Major Cations
<1Calcium <1 <1 3 11mg/L17440-70-2
<1Magnesium <1 <1 <1 2mg/L17439-95-4
3710Sodium 223 54 58 66mg/L17440-23-5
9Potassium 2 2 2 3mg/L17440-09-7
EG020T: Total Metals by ICP-MS
15.7Aluminium 2.37 4.33 0.02 0.02mg/L0.017429-90-5
<0.001Dysprosium <0.001 0.007 <0.001 <0.001mg/L0.0017429-91-6
<0.001Silver <0.001 <0.001 <0.001 <0.001mg/L0.0017440-22-4
0.021Arsenic 0.007 0.006 <0.001 <0.001mg/L0.0017440-38-2
<0.001Bismuth <0.001 <0.001 <0.001 <0.001mg/L0.0017440-69-9
<0.001Erbium <0.001 0.002 <0.001 <0.001mg/L0.0017440-52-0
0.08Boron 0.06 0.28 <0.05 <0.05mg/L0.057440-42-8
<0.001Europium <0.001 0.007 <0.001 <0.001mg/L0.0017440-53-1
0.006Strontium 0.002 0.044 0.019 0.076mg/L0.0017440-24-6
0.182Barium 0.144 1.51 0.158 0.483mg/L0.0017440-39-3
4 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T05 - pH 8.0
2018 bene combined
tailings
T04 - pH 9.0
2018 bene combined
tailings
T03 - pH 10.5
2018 bene combined
tailings
T02 - pH 12.0
2018 bene combined
tailings
T01 - pH 13.0
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-006ES1907149-005ES1907149-004ES1907149-003ES1907149-002UnitLORCAS NumberCompound
Result Result Result Result Result
EG020T: Total Metals by ICP-MS - Continued
<0.001Gadolinium <0.001 0.019 <0.001 <0.001mg/L0.0017440-54-2
<0.01Titanium <0.01 0.14 <0.01 <0.01mg/L0.017440-32-6
<0.001Beryllium <0.001 0.003 <0.001 <0.001mg/L0.0017440-41-7
0.005Gallium 0.003 0.013 <0.001 <0.001mg/L0.0017440-55-3
<0.0001Cadmium <0.0001 0.0003 0.0001 <0.0001mg/L0.00017440-43-9
<0.01Hafnium <0.01 <0.01 <0.01 <0.01mg/L0.017440-58-6
<0.005Tellurium <0.005 <0.005 <0.005 <0.005mg/L0.00522541-49-7
<0.001Cobalt <0.001 0.008 <0.001 <0.001mg/L0.0017440-48-4
<0.001Holmium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-60-0
0.064Uranium 0.002 0.006 0.002 0.002mg/L0.0017440-61-1
<0.001Caesium <0.001 0.005 <0.001 <0.001mg/L0.0017440-46-2
0.004Chromium 0.001 0.013 <0.001 <0.001mg/L0.0017440-47-3
<0.001Indium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-74-6
0.004Copper 0.002 0.017 0.004 0.004mg/L0.0017440-50-8
<0.001Lanthanum 0.002 0.084 <0.001 <0.001mg/L0.0017439-91-0
0.016Rubidium 0.003 0.059 0.003 0.005mg/L0.0017440-17-7
<0.001Lithium <0.001 0.022 0.004 0.009mg/L0.0017439-93-2
<0.001Lutetium <0.001 <0.001 <0.001 <0.001mg/L0.0017439-94-3
<0.001Thorium <0.001 0.044 <0.001 <0.001mg/L0.0017440-29-1
0.002Cerium 0.009 0.349 0.002 0.001mg/L0.0017440-45-1
0.005Manganese 0.061 2.35 0.054 0.034mg/L0.0017439-96-5
0.001Neodymium 0.008 0.273 0.001 <0.001mg/L0.0017440-00-8
0.064Molybdenum 0.037 0.010 0.024 0.020mg/L0.0017439-98-7
<0.001Praseodymium 0.002 0.060 <0.001 <0.001mg/L0.0017440-10-0
<0.001Nickel <0.001 0.012 <0.001 <0.001mg/L0.0017440-02-0
<0.001Samarium <0.001 0.031 <0.001 <0.001mg/L0.0017440-19-9
0.005Lead 0.003 0.127 0.001 <0.001mg/L0.0017439-92-1
<0.001Terbium <0.001 0.002 <0.001 <0.001mg/L0.0017440-27-9
<0.001Antimony <0.001 <0.001 <0.001 <0.001mg/L0.0017440-36-0
<0.001Thulium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-30-4
<0.01Selenium <0.01 <0.01 <0.01 <0.01mg/L0.017782-49-2
<0.001Ytterbium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-64-4
0.054Tin 0.002 <0.001 <0.001 <0.001mg/L0.0017440-31-5
5 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T05 - pH 8.0
2018 bene combined
tailings
T04 - pH 9.0
2018 bene combined
tailings
T03 - pH 10.5
2018 bene combined
tailings
T02 - pH 12.0
2018 bene combined
tailings
T01 - pH 13.0
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-006ES1907149-005ES1907149-004ES1907149-003ES1907149-002UnitLORCAS NumberCompound
Result Result Result Result Result
EG020T: Total Metals by ICP-MS - Continued
<0.001Yttrium <0.001 0.018 <0.001 <0.001mg/L0.0017440-65-5
<0.001Thallium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-28-0
<0.005Zirconium <0.005 <0.005 <0.005 <0.005mg/L0.0057440-67-7
0.21Vanadium 0.10 0.05 <0.01 <0.01mg/L0.017440-62-2
0.075Zinc 0.196 0.291 0.019 0.167mg/L0.0057440-66-6
0.07Iron 0.50 16.1 0.07 <0.05mg/L0.057439-89-6
EG035T: Total Recoverable Mercury by FIMS
<0.0001Mercury <0.0001 <0.0001 <0.0001 <0.0001mg/L0.00017439-97-6
EK040P: Fluoride by PC Titrator
4.8Fluoride 0.5 0.6 0.6 0.6mg/L0.116984-48-8
6 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
B01
2018 bene combined
tailings
T09 - pH 2.0
2018 bene combined
tailings
T08 - pH 4.0
2018 bene combined
tailings
T07 - pH 5.5
2018 bene combined
tailings
T06 - pH Neutral
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-011ES1907149-010ES1907149-009ES1907149-008ES1907149-007UnitLORCAS NumberCompound
Result Result Result Result Result
EA005P: pH by PC Titrator
6.44 5.63 3.52 1.96 6.64pH Unit0.01----pH Value
EA010P: Conductivity by PC Titrator
658 702 1020 8260 <1µS/cm1----Electrical Conductivity @ 25°C
EA016: Calculated TDS (from Electrical Conductivity)
428 456 663 5370 <1mg/L1----Total Dissolved Solids (Calc.)
EA065: Total Hardness as CaCO3
122 138 225 253 <1mg/L1----Total Hardness as CaCO3
ED037P: Alkalinity by PC Titrator
<1Hydroxide Alkalinity as CaCO3 <1 <1 <1 <1mg/L1DMO-210-001
<1Carbonate Alkalinity as CaCO3 <1 <1 <1 <1mg/L13812-32-6
15Bicarbonate Alkalinity as CaCO3 8 <1 <1 <1mg/L171-52-3
15 8 <1 <1 <1mg/L1----Total Alkalinity as CaCO3
ED041G: Sulfate (Turbidimetric) as SO4 2- by DA
6Sulfate as SO4 - Turbidimetric <1 <1 <10 <1mg/L114808-79-8
ED045G: Chloride by Discrete Analyser
12Chloride <1 <1 11 <1mg/L116887-00-6
ED093F: Dissolved Major Cations
34Calcium 39 62 65 <1mg/L17440-70-2
9Magnesium 10 17 22 <1mg/L17439-95-4
70Sodium 73 76 73 <1mg/L17440-23-5
5Potassium 6 10 17 <1mg/L17440-09-7
EG020T: Total Metals by ICP-MS
0.03Aluminium 0.01 4.39 19.5 0.01mg/L0.017429-90-5
<0.001Dysprosium <0.001 0.010 0.057 <0.001mg/L0.0017429-91-6
<0.001Silver <0.001 <0.001 <0.001 <0.001mg/L0.0017440-22-4
<0.001Arsenic <0.001 0.004 0.034 <0.001mg/L0.0017440-38-2
<0.001Bismuth <0.001 <0.001 <0.001 <0.001mg/L0.0017440-69-9
<0.001Erbium <0.001 0.003 0.015 <0.001mg/L0.0017440-52-0
0.18Boron 0.07 0.34 0.53 <0.05mg/L0.057440-42-8
<0.001Europium <0.001 0.008 0.051 <0.001mg/L0.0017440-53-1
0.295Strontium 0.378 0.737 0.886 0.005mg/L0.0017440-24-6
1.38Barium 1.04 5.18 13.8 0.088mg/L0.0017440-39-3
7 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
B01
2018 bene combined
tailings
T09 - pH 2.0
2018 bene combined
tailings
T08 - pH 4.0
2018 bene combined
tailings
T07 - pH 5.5
2018 bene combined
tailings
T06 - pH Neutral
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-011ES1907149-010ES1907149-009ES1907149-008ES1907149-007UnitLORCAS NumberCompound
Result Result Result Result Result
EG020T: Total Metals by ICP-MS - Continued
<0.001Gadolinium <0.001 0.024 0.143 <0.001mg/L0.0017440-54-2
<0.01Titanium <0.01 <0.01 0.01 <0.01mg/L0.017440-32-6
<0.001Beryllium <0.001 0.054 0.076 <0.001mg/L0.0017440-41-7
<0.001Gallium <0.001 0.013 0.094 <0.001mg/L0.0017440-55-3
0.0004Cadmium 0.0004 0.0033 0.0042 <0.0001mg/L0.00017440-43-9
<0.01Hafnium <0.01 <0.01 <0.01 <0.01mg/L0.017440-58-6
<0.005Tellurium <0.005 <0.005 <0.005 <0.005mg/L0.00522541-49-7
<0.001Cobalt 0.004 0.059 0.141 <0.001mg/L0.0017440-48-4
<0.001Holmium <0.001 0.001 0.007 <0.001mg/L0.0017440-60-0
<0.001Uranium <0.001 0.023 0.265 <0.001mg/L0.0017440-61-1
<0.001Caesium <0.001 <0.001 0.001 <0.001mg/L0.0017440-46-2
<0.001Chromium <0.001 0.006 0.080 <0.001mg/L0.0017440-47-3
<0.001Indium <0.001 <0.001 <0.001 <0.001mg/L0.0017440-74-6
0.004Copper 0.004 0.030 0.198 <0.001mg/L0.0017440-50-8
<0.001Lanthanum 0.003 0.103 0.860 <0.001mg/L0.0017439-91-0
0.011Rubidium 0.016 0.043 0.148 <0.001mg/L0.0017440-17-7
0.022Lithium 0.024 0.044 0.103 <0.001mg/L0.0017439-93-2
<0.001Lutetium <0.001 <0.001 0.001 <0.001mg/L0.0017439-94-3
0.002Thorium <0.001 <0.001 0.053 <0.001mg/L0.0017440-29-1
0.001Cerium 0.006 0.329 2.36 <0.001mg/L0.0017440-45-1
1.03Manganese 2.40 13.3 35.0 0.014mg/L0.0017439-96-5
<0.001Neodymium 0.004 0.290 2.15 <0.001mg/L0.0017440-00-8
<0.001Molybdenum <0.001 <0.001 <0.001 <0.001mg/L0.0017439-98-7
<0.001Praseodymium <0.001 0.064 0.555 <0.001mg/L0.0017440-10-0
0.005Nickel 0.012 0.045 0.080 <0.001mg/L0.0017440-02-0
<0.001Samarium <0.001 0.035 0.238 <0.001mg/L0.0017440-19-9
<0.001Lead <0.001 0.014 1.04 <0.001mg/L0.0017439-92-1
<0.001Terbium <0.001 0.003 0.015 <0.001mg/L0.0017440-27-9
<0.001Antimony <0.001 <0.001 <0.001 <0.001mg/L0.0017440-36-0
<0.001Thulium <0.001 <0.001 0.001 <0.001mg/L0.0017440-30-4
<0.01Selenium <0.01 <0.01 0.04 <0.01mg/L0.017782-49-2
<0.001Ytterbium <0.001 0.002 0.008 <0.001mg/L0.0017440-64-4
<0.001Tin <0.001 <0.001 <0.001 <0.001mg/L0.0017440-31-5
8 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
B01
2018 bene combined
tailings
T09 - pH 2.0
2018 bene combined
tailings
T08 - pH 4.0
2018 bene combined
tailings
T07 - pH 5.5
2018 bene combined
tailings
T06 - pH Neutral
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-011ES1907149-010ES1907149-009ES1907149-008ES1907149-007UnitLORCAS NumberCompound
Result Result Result Result Result
EG020T: Total Metals by ICP-MS - Continued
<0.001Yttrium <0.001 0.033 0.162 <0.001mg/L0.0017440-65-5
<0.001Thallium <0.001 <0.001 0.004 <0.001mg/L0.0017440-28-0
<0.005Zirconium <0.005 <0.005 <0.005 <0.005mg/L0.0057440-67-7
<0.01Vanadium <0.01 <0.01 <0.01 <0.01mg/L0.017440-62-2
0.585Zinc 0.689 1.21 1.58 0.014mg/L0.0057440-66-6
<0.05Iron <0.05 <0.05 26.7 <0.05mg/L0.057439-89-6
EG035T: Total Recoverable Mercury by FIMS
<0.0001Mercury <0.0001 <0.0001 <0.0001 <0.0001mg/L0.00017439-97-6
EK040P: Fluoride by PC Titrator
0.3Fluoride 0.2 1.2 1.0 <0.1mg/L0.116984-48-8
9 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
------------2018 bene combined
tailings
B03
2018 bene combined
tailings
B02
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
------------26-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
------------------------ES1907149-013ES1907149-012UnitLORCAS NumberCompound
Result Result ---- ---- ----
EA005P: pH by PC Titrator
1.74 12.9 ---- ---- ----pH Unit0.01----pH Value
EA010P: Conductivity by PC Titrator
13300 35600 ---- ---- ----µS/cm1----Electrical Conductivity @ 25°C
EA016: Calculated TDS (from Electrical Conductivity)
8640 23100 ---- ---- ----mg/L1----Total Dissolved Solids (Calc.)
EA065: Total Hardness as CaCO3
<1 <1 ---- ---- ----mg/L1----Total Hardness as CaCO3
ED037P: Alkalinity by PC Titrator
<1Hydroxide Alkalinity as CaCO3 6120 ---- ---- ----mg/L1DMO-210-001
<1Carbonate Alkalinity as CaCO3 1050 ---- ---- ----mg/L13812-32-6
<1Bicarbonate Alkalinity as CaCO3 <1 ---- ---- ----mg/L171-52-3
<1 7180 ---- ---- ----mg/L1----Total Alkalinity as CaCO3
ED041G: Sulfate (Turbidimetric) as SO4 2- by DA
<10Sulfate as SO4 - Turbidimetric <1 ---- ---- ----mg/L114808-79-8
ED045G: Chloride by Discrete Analyser
<1Chloride 11 ---- ---- ----mg/L116887-00-6
ED093F: Dissolved Major Cations
<1Calcium <1 ---- ---- ----mg/L17440-70-2
<1Magnesium <1 ---- ---- ----mg/L17439-95-4
<1Sodium 3800 ---- ---- ----mg/L17440-23-5
<1Potassium 1 ---- ---- ----mg/L17440-09-7
EG020T: Total Metals by ICP-MS
0.02Aluminium 0.17 ---- ---- ----mg/L0.017429-90-5
<0.001Dysprosium <0.001 ---- ---- ----mg/L0.0017429-91-6
<0.001Silver <0.001 ---- ---- ----mg/L0.0017440-22-4
<0.001Arsenic <0.001 ---- ---- ----mg/L0.0017440-38-2
<0.001Bismuth <0.001 ---- ---- ----mg/L0.0017440-69-9
<0.001Erbium <0.001 ---- ---- ----mg/L0.0017440-52-0
<0.05Boron <0.05 ---- ---- ----mg/L0.057440-42-8
<0.001Europium <0.001 ---- ---- ----mg/L0.0017440-53-1
<0.001Strontium 0.011 ---- ---- ----mg/L0.0017440-24-6
0.020Barium 0.453 ---- ---- ----mg/L0.0017440-39-3
10 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
------------2018 bene combined
tailings
B03
2018 bene combined
tailings
B02
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
------------26-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
------------------------ES1907149-013ES1907149-012UnitLORCAS NumberCompound
Result Result ---- ---- ----
EG020T: Total Metals by ICP-MS - Continued
<0.001Gadolinium <0.001 ---- ---- ----mg/L0.0017440-54-2
<0.01Titanium <0.01 ---- ---- ----mg/L0.017440-32-6
<0.001Beryllium <0.001 ---- ---- ----mg/L0.0017440-41-7
<0.001Gallium <0.001 ---- ---- ----mg/L0.0017440-55-3
<0.0001Cadmium <0.0001 ---- ---- ----mg/L0.00017440-43-9
<0.01Hafnium <0.01 ---- ---- ----mg/L0.017440-58-6
<0.005Tellurium <0.005 ---- ---- ----mg/L0.00522541-49-7
<0.001Cobalt <0.001 ---- ---- ----mg/L0.0017440-48-4
<0.001Holmium <0.001 ---- ---- ----mg/L0.0017440-60-0
<0.001Uranium <0.001 ---- ---- ----mg/L0.0017440-61-1
<0.001Caesium <0.001 ---- ---- ----mg/L0.0017440-46-2
<0.001Chromium <0.001 ---- ---- ----mg/L0.0017440-47-3
<0.001Indium <0.001 ---- ---- ----mg/L0.0017440-74-6
<0.001Copper 0.005 ---- ---- ----mg/L0.0017440-50-8
<0.001Lanthanum <0.001 ---- ---- ----mg/L0.0017439-91-0
<0.001Rubidium <0.001 ---- ---- ----mg/L0.0017440-17-7
<0.001Lithium <0.001 ---- ---- ----mg/L0.0017439-93-2
<0.001Lutetium <0.001 ---- ---- ----mg/L0.0017439-94-3
<0.001Thorium <0.001 ---- ---- ----mg/L0.0017440-29-1
<0.001Cerium <0.001 ---- ---- ----mg/L0.0017440-45-1
0.009Manganese 0.003 ---- ---- ----mg/L0.0017439-96-5
<0.001Neodymium <0.001 ---- ---- ----mg/L0.0017440-00-8
<0.001Molybdenum 0.002 ---- ---- ----mg/L0.0017439-98-7
<0.001Praseodymium <0.001 ---- ---- ----mg/L0.0017440-10-0
<0.001Nickel <0.001 ---- ---- ----mg/L0.0017440-02-0
<0.001Samarium <0.001 ---- ---- ----mg/L0.0017440-19-9
0.002Lead 0.002 ---- ---- ----mg/L0.0017439-92-1
<0.001Terbium <0.001 ---- ---- ----mg/L0.0017440-27-9
<0.001Antimony <0.001 ---- ---- ----mg/L0.0017440-36-0
<0.001Thulium <0.001 ---- ---- ----mg/L0.0017440-30-4
<0.01Selenium <0.01 ---- ---- ----mg/L0.017782-49-2
<0.001Ytterbium <0.001 ---- ---- ----mg/L0.0017440-64-4
<0.001Tin 0.039 ---- ---- ----mg/L0.0017440-31-5
11 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
------------2018 bene combined
tailings
B03
2018 bene combined
tailings
B02
Client sample IDSub-Matrix: LEACHATE
(Matrix: WATER)
------------26-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
------------------------ES1907149-013ES1907149-012UnitLORCAS NumberCompound
Result Result ---- ---- ----
EG020T: Total Metals by ICP-MS - Continued
<0.001Yttrium <0.001 ---- ---- ----mg/L0.0017440-65-5
<0.001Thallium <0.001 ---- ---- ----mg/L0.0017440-28-0
<0.005Zirconium <0.005 ---- ---- ----mg/L0.0057440-67-7
<0.01Vanadium <0.01 ---- ---- ----mg/L0.017440-62-2
0.010Zinc 0.072 ---- ---- ----mg/L0.0057440-66-6
1.10Iron <0.05 ---- ---- ----mg/L0.057439-89-6
EG035T: Total Recoverable Mercury by FIMS
<0.0001Mercury <0.0001 ---- ---- ----mg/L0.00017439-97-6
EK040P: Fluoride by PC Titrator
<0.1Fluoride 3.8 ---- ---- ----mg/L0.116984-48-8
12 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T04 - pH 9.0
2018 bene combined
tailings
T03 - pH 10.5
2018 bene combined
tailings
T02 - pH 12.0
2018 bene combined
tailings
T01 - pH 13.0
2018 bene combined
tailings
Client sample IDSub-Matrix: SOIL
(Matrix: SOIL)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-005ES1907149-004ES1907149-003ES1907149-002ES1907149-001UnitLORCAS NumberCompound
Result Result Result Result Result
EA002: pH 1:5 (Soils)
10.1 ---- ---- ---- ----pH Unit0.1----pH Value
EA009: Nett Acid Production Potential
-7.3 ---- ---- ---- ----kg H2SO4/t0.5----Net Acid Production Potential
EA010: Conductivity (1:5)
276 ---- ---- ---- ----µS/cm1----Electrical Conductivity @ 25°C
EA011: Net Acid Generation
8.9 ---- ---- ---- ----pH Unit0.1----pH (OX)
<0.1 ---- ---- ---- ----kg H2SO4/t0.1----NAG (pH 4.5)
<0.1 ---- ---- ---- ----kg H2SO4/t0.1----NAG (pH 7.0)
EA013: Acid Neutralising Capacity
7.3 ---- ---- ---- ----kg H2SO4
equiv./t
0.5----ANC as H2SO4
0.7 ---- ---- ---- ----% CaCO30.1----ANC as CaCO3
0 ---- ---- ---- ----Fizz Unit0----Fizz Rating
EA055: Moisture Content (Dried @ 105-110°C)
<1.0 ---- ---- ---- ----%1.0----Moisture Content
ED042T: Total Sulfur by LECO
<0.01 ---- ---- ---- ----%0.01----Sulfur - Total as S (LECO)
EG005(ED093)T: Total Metals by ICP-AES
3920Aluminium ---- ---- ---- ----mg/kg507429-90-5
<50Boron ---- ---- ---- ----mg/kg507440-42-8
43600Iron ---- ---- ---- ----mg/kg507439-89-6
EG020T: Total Metals by ICP-MS
7.8Arsenic ---- ---- ---- ----mg/kg0.17440-38-2
16Selenium ---- ---- ---- ----mg/kg17782-49-2
0.7Silver ---- ---- ---- ----mg/kg0.17440-22-4
1020Barium ---- ---- ---- ----mg/kg0.17440-39-3
0.8Thallium ---- ---- ---- ----mg/kg0.17440-28-0
3.4Beryllium ---- ---- ---- ----mg/kg0.17440-41-7
0.2Cadmium ---- ---- ---- ----mg/kg0.17440-43-9
0.3Bismuth ---- ---- ---- ----mg/kg0.17440-69-9
12.8Cobalt ---- ---- ---- ----mg/kg0.17440-48-4
13 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T04 - pH 9.0
2018 bene combined
tailings
T03 - pH 10.5
2018 bene combined
tailings
T02 - pH 12.0
2018 bene combined
tailings
T01 - pH 13.0
2018 bene combined
tailings
Client sample IDSub-Matrix: SOIL
(Matrix: SOIL)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-005ES1907149-004ES1907149-003ES1907149-002ES1907149-001UnitLORCAS NumberCompound
Result Result Result Result Result
EG020T: Total Metals by ICP-MS - Continued
58.5Chromium ---- ---- ---- ----mg/kg0.17440-47-3
25.0Copper ---- ---- ---- ----mg/kg0.17440-50-8
153Thorium ---- ---- ---- ----mg/kg0.17440-29-1
3210Manganese ---- ---- ---- ----mg/kg0.17439-96-5
58.1Strontium ---- ---- ---- ----mg/kg0.17440-24-6
4.7Molybdenum ---- ---- ---- ----mg/kg0.17439-98-7
33.4Nickel ---- ---- ---- ----mg/kg0.17440-02-0
255Lead ---- ---- ---- ----mg/kg0.17439-92-1
<0.1Antimony ---- ---- ---- ----mg/kg0.17440-36-0
8.4Uranium ---- ---- ---- ----mg/kg0.17440-61-1
86.6Zinc ---- ---- ---- ----mg/kg0.57440-66-6
17.7Lithium ---- ---- ---- ----mg/kg0.17439-93-2
20Vanadium ---- ---- ---- ----mg/kg17440-62-2
3.4Tin ---- ---- ---- ----mg/kg0.17440-31-5
EG035T: Total Recoverable Mercury by FIMS
<0.1Mercury ---- ---- ---- ----mg/kg0.17439-97-6
EN58-2: Leaching Environmental Assessment Framework (LEAF) Method 1313
---- 2.0 2.0 2.0 2.0mm0.1----Particle Size (>85 wt% passing through)
---- 4N HNO3 4N HNO3 4N HNO3 4N HNO3------Acid
---- <0.1 <0.1 <0.1 0.1mL0.1----Volume of acid
---- 1N NaOH 1N NaOH 1N NaOH 1N NaOH------Base
---- 70.0 4.0 <0.1 <0.1mL0.1----Volume of base
---- 330 396 400 400mL1----Volume of water
---- 48.0 48.0 48.0 48.0hours0.5----Extraction Contact Time
---- 22.4 22.4 22.4 22.4°C0.5----Ambient Temperature
---- 40.0 40.0 40.0 40.0g0.1----Mass of "as tested" solid
---- 13.0 12.0 10.5 9.0pH Unit0.1----Target pH
---- 22.4 22.4 21.9 23.1°C0.1----Ambient Temperature during extraction
14 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
2018 bene combined
tailings
T09 - pH 2.0
2018 bene combined
tailings
T08 - pH 4.0
2018 bene combined
tailings
T07 - pH 5.5
2018 bene combined
tailings
T06 - pH Neutral
2018 bene combined
tailings
T05 - pH 8.0
Client sample IDSub-Matrix: SOIL
(Matrix: SOIL)
26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
ES1907149-010ES1907149-009ES1907149-008ES1907149-007ES1907149-006UnitLORCAS NumberCompound
Result Result Result Result Result
EN58-2: Leaching Environmental Assessment Framework (LEAF) Method 1313
2.0 2.0 2.0 2.0 2.0mm0.1----Particle Size (>85 wt% passing through)
4N HNO3 4N HNO3 4N HNO3 4N HNO3 4N HNO3------Acid
0.2 0.5 0.6 0.9 3.0mL0.1----Volume of acid
1N NaOH 1N NaOH 1N NaOH 1N NaOH 1N NaOH------Base
<0.1 <0.1 <0.1 <0.1 <0.1mL0.1----Volume of base
400 400 399 399 397mL1----Volume of water
48.0 48.0 48.0 48.0 48.0hours0.5----Extraction Contact Time
22.4 22.4 22.4 22.4 22.4°C0.5----Ambient Temperature
40.0 40.0 40.0 40.0 40.0g0.1----Mass of "as tested" solid
8.0 7.0 5.5 4.0 2.0pH Unit0.1----Target pH
22.3 22.4 23.1 22.3 22.4°C0.1----Ambient Temperature during extraction
15 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
--------2018 bene combined
tailings
B03
2018 bene combined
tailings
B02
2018 bene combined
tailings
B01
Client sample IDSub-Matrix: SOIL
(Matrix: SOIL)
--------26-Nov-2018 00:0026-Nov-2018 00:0026-Nov-2018 00:00Client sampling date / time
----------------ES1907149-013ES1907149-012ES1907149-011UnitLORCAS NumberCompound
Result Result Result ---- ----
EN58-2: Leaching Environmental Assessment Framework (LEAF) Method 1313
2.0 2.0 2.0 ---- ----mm0.1----Particle Size (>85 wt% passing through)
4N HNO3 4N HNO3 4N HNO3 ---- ----------Acid
<0.1 3.0 <0.1 ---- ----mL0.1----Volume of acid
1N NaOH 1N NaOH 1N NaOH ---- ----------Base
<0.1 <0.1 70.0 ---- ----mL0.1----Volume of base
400 397 330 ---- ----mL1----Volume of water
48.0 48.0 48.0 ---- ----hours0.5----Extraction Contact Time
22.4 22.4 22.4 ---- ----°C0.5----Ambient Temperature
<0.1 <0.1 <0.1 ---- ----g0.1----Mass of "as tested" solid
Natural 2.0 13.0 ---- ----pH Unit0.1----Target pH
22.4 22.4 22.4 ---- ----°C0.1----Ambient Temperature during extraction
16 of 16:Page
Work Order :
:Client
ES1907149 Amendment 1
3219134:Project
GHD PTY LTD
Analytical Results
----------------Hastings pilot plant
filtrate
Client sample IDSub-Matrix: WATER
(Matrix: WATER)
----------------26-Nov-2018 00:00Client sampling date / time
--------------------------------ES1907149-014UnitLORCAS NumberCompound
Result ---- ---- ---- ----
EA005P: pH by PC Titrator
11.8 ---- ---- ---- ----pH Unit0.01----pH Value
EA010P: Conductivity by PC Titrator
5220 ---- ---- ---- ----µS/cm1----Electrical Conductivity @ 25°C
EA016: Calculated TDS (from Electrical Conductivity)
3390 ---- ---- ---- ----mg/L1----Total Dissolved Solids (Calc.)
EA025: Total Suspended Solids dried at 104 ± 2°C
16 ---- ---- ---- ----mg/L5----Suspended Solids (SS)
ED037P: Alkalinity by PC Titrator
703Hydroxide Alkalinity as CaCO3 ---- ---- ---- ----mg/L1DMO-210-001
213Carbonate Alkalinity as CaCO3 ---- ---- ---- ----mg/L13812-32-6
<1Bicarbonate Alkalinity as CaCO3 ---- ---- ---- ----mg/L171-52-3
914 ---- ---- ---- ----mg/L1----Total Alkalinity as CaCO3
ED041G: Sulfate (Turbidimetric) as SO4 2- by DA
182Sulfate as SO4 - Turbidimetric ---- ---- ---- ----mg/L114808-79-8
ED045G: Chloride by Discrete Analyser
285Chloride ---- ---- ---- ----mg/L116887-00-6
EK040P: Fluoride by PC Titrator
2.6Fluoride ---- ---- ---- ----mg/L0.116984-48-8
ANALYSIS REPORT: Created by Leigh Wills - ALS Sydney 2000
DATE COMPLETED:
SAMPLE TYPE:
No. of SAMPLES:
ISSUING LABORATORY: ALS BRISBANE
Address: 32 Shand Street 07 3243 7222
CONTACT: Sarah Gilmour
COMMENTS
EA046 : NATA accreditation does not cover performance of this service.
Signatory
07 3243 [email protected] E-mail:
Australian Laboratory Services Pty Ltd (ABN 84 009 936 029)
STAFFORD QLD 4053 Facsimile:
Acid Buffering Characteristic Curve (ABCC) REPORT
Batch: ES1907149
DATE RECEIVED:
26/01/2018Brisbane
8/03/2019ADDRESS:
LABORATORY:
DATE SAMPLED:CLIENT: GHD PTY LTD2 SALAMANCA SQUAREHOBART TAS, AUSTRALIA 7000
Telephone:
22/03/2019
1Soil
Work Order : ES1907149 Client ID:
Sub Matrix SoilClient Sample Identification 1Client Sample Identification 2Sample Date 26/01/2018
Method Analyte Units LOR1
ES1907149
EA046 - A Titration information
HCl Molarity: M 0.1Increments: mL 0.1
Weight (g) 2
ANC kgH2SO4/t 7.3
EA046 -B - Curve information
Addition
mLs added (total)
kg H2SO4/t pH Addition
mLs added (total)
kg H2SO4/t pH
0 0 0 8.44 36 3.6 8.82 3.081 0.1 0.245 7.86 37 3.7 9.065 3.052 0.2 0.49 7.46 38 3.8 9.31 3.033 0.3 0.735 7.23 39 3.9 9.555 3.004 0.4 0.98 7.08 40 4 9.8 2.975 0.5 1.225 6.94 41 4.1 10.045 2.956 0.6 1.47 6.78 42 4.2 10.29 2.937 0.7 1.715 6.58 43 4.3 10.535 2.918 0.8 1.96 6.36 44 4.4 10.78 2.899 0.9 2.205 6.15 45 4.5 11.025 2.8710 1 2.45 5.95 46 4.6 11.27 2.8511 1.1 2.695 5.66 47 4.7 11.515 2.8312 1.2 2.94 5.32 48 4.8 11.76 2.8113 1.3 3.185 5.00 49 4.9 12.005 2.8014 1.4 3.43 4.80 50 5 12.25 2.7915 1.5 3.675 4.64 51 5.1 12.495 2.7716 1.6 3.92 4.50 52 5.2 12.74 2.7617 1.7 4.165 4.33 53 5.3 12.985 2.7418 1.8 4.41 4.20 54 5.4 13.23 2.7319 1.9 4.655 4.08 55 5.5 13.475 2.7120 2 4.9 3.98 56 5.6 13.72 2.7021 2.1 5.145 3.89 57 5.7 13.965 2.6922 2.2 5.39 3.79 58 5.8 14.21 2.6723 2.3 5.635 3.70 59 5.9 14.455 2.6624 2.4 5.88 3.67 60 6 14.7 2.6525 2.5 6.125 3.59 61 6.1 14.945 2.6326 2.6 6.37 3.52 62 6.2 15.19 2.6227 2.7 6.615 3.46 63 6.3 15.435 2.6128 2.8 6.86 3.40 64 6.4 15.68 2.5929 2.9 7.105 3.35 65 6.5 15.925 2.5930 3 7.35 3.30 66 6.6 16.17 2.5731 3.1 7.595 3.26 67 6.7 16.415 2.5632 3.2 7.84 3.22 68 6.8 16.66 2.5533 3.3 8.085 3.18 69 6.9 16.905 2.5434 3.4 8.33 3.15 70 7 17.15 2.5335 3.5 8.575 3.11 71 7.1 17.395 2.52
GHD PTY LTD
2018 bene combined tailings
Work Order : ES1907149 Client ID:
Sub Matrix SoilClient Sample Identification 1Client Sample Identification 2Sample Date 26/01/2018
Method Analyte Units LOR1
ES1907149
EA046 - A Titration information
HCl Molarity: M 0.1Increments: mL 0.1Weight (g) 2ANC kgH2SO4/t 7.3
EA046 -B - Curve information
Addition
mLs added (total)
kg H2SO4/t pH Addition
mLs added (total)
kg H2SO4/t pH
72 7.2 17.64 2.5173 7.3 17.885 2.50
GHD PTY LTD
2018 bene combined tailings
Work Order : ES1907149 Client ID:
Sub Matrix SoilClient Sample Identification 1Client Sample Identification 2Sample Date 26/01/2018
Method Analyte Units LOR1 Check
ES1907149
EA046 - A Titration information
HCl Molarity: M 0.1Increments: mL 0.1Weight (g) 2ANC kgH2SO4/t 7.3
EA046 -B - Curve information
Addition
mLs added (total)
kg H2SO4/t pH Addition
mLs added (total)
kg H2SO4/t pH
0 0 0 8.78 36 3.6 8.82 3.111 0.1 0.245 7.91 37 3.7 9.065 3.092 0.2 0.49 7.54 38 3.8 9.31 3.073 0.3 0.735 7.35 39 3.9 9.555 3.044 0.4 0.98 7.17 40 4 9.8 3.025 0.5 1.225 6.97 41 4.1 10.045 3.016 0.6 1.47 6.72 42 4.2 10.29 2.997 0.7 1.715 6.40 43 4.3 10.535 2.978 0.8 1.96 6.04 44 4.4 10.78 2.969 0.9 2.205 5.70 45 4.5 11.025 2.9410 1 2.45 5.40 46 4.6 11.27 2.9311 1.1 2.695 5.14 47 4.7 11.515 2.9112 1.2 2.94 4.88 48 4.8 11.76 2.9013 1.3 3.185 4.68 49 4.9 12.005 2.8914 1.4 3.43 4.50 50 5 12.25 2.8715 1.5 3.675 4.36 51 5.1 12.495 2.8616 1.6 3.92 4.23 52 5.2 12.74 2.8517 1.7 4.165 4.10 53 5.3 12.985 2.8418 1.8 4.41 3.99 54 5.4 13.23 2.8319 1.9 4.655 3.90 55 5.5 13.475 2.8220 2 4.9 3.82 56 5.6 13.72 2.8121 2.1 5.145 3.74 57 5.7 13.965 2.8022 2.2 5.39 3.67 58 5.8 14.21 2.7923 2.3 5.635 3.60 59 5.9 14.455 2.7824 2.4 5.88 3.54 60 6 14.7 2.7725 2.5 6.125 3.49 61 6.1 14.945 2.7526 2.6 6.37 3.45 62 6.2 15.19 2.7427 2.7 6.615 3.40 63 6.3 15.435 2.7428 2.8 6.86 3.36 64 6.4 15.68 2.7329 2.9 7.105 3.32 65 6.5 15.925 2.7230 3 7.35 3.28 66 6.6 16.17 2.7231 3.1 7.595 3.25 67 6.7 16.415 2.7132 3.2 7.84 3.22 68 6.8 16.66 2.7033 3.3 8.085 3.19 69 6.9 16.905 2.6934 3.4 8.33 3.16 70 7 17.15 2.6835 3.5 8.575 3.14 71 7.1 17.395 2.68
GHD PTY LTD
2018 bene combined tailings
Work Order : ES1907149 Client ID:
Sub Matrix SoilClient Sample Identification 1Client Sample Identification 2Sample Date 26/01/2018
Method Analyte Units LOR1 Check
ES1907149
EA046 - A Titration information
HCl Molarity: M 0.1Increments: mL 0.1Weight (g) 2ANC kgH2SO4/t 7.3
EA046 -B - Curve information
Addition
mLs added (total)
kg H2SO4/t pH Addition
mLs added (total)
kg H2SO4/t pH
72 7.2 17.64 2.67 108 10.8 26.46 2.5073 7.3 17.885 2.66 109 10.9 26.705 2.5074 7.4 18.13 2.6675 7.5 18.375 2.6576 7.6 18.62 2.6477 7.7 18.865 2.6478 7.8 19.11 2.6379 7.9 19.355 2.6280 8 19.6 2.6281 8.1 19.845 2.6182 8.2 20.09 2.6183 8.3 20.335 2.6084 8.4 20.58 2.6085 8.5 20.825 2.5986 8.6 21.07 2.5987 8.7 21.315 2.5888 8.8 21.56 2.5789 8.9 21.805 2.5790 9 22.05 2.5791 9.1 22.295 2.5692 9.2 22.54 2.5693 9.3 22.785 2.5594 9.4 23.03 2.5595 9.5 23.275 2.5596 9.6 23.52 2.5497 9.7 23.765 2.5498 9.8 24.01 2.5399 9.9 24.255 2.53100 10 24.5 2.53101 10.1 24.745 2.52102 10.2 24.99 2.52103 10.3 25.235 2.51104 10.4 25.48 2.51105 10.5 25.725 2.51106 10.6 25.97 2.51107 10.7 26.215 2.50
GHD PTY LTD
2018 bene combined tailings
0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5
10.010.511.011.512.012.513.013.514.0
0 5 10 15 20 25 30
pH
kg H2SO4/t
ES1907149 - 1 and Check 1 (2018 bene combined tailings)Acid Buffering Characteristic Curve
pH/H2SO4/t
pH/H2SO4/t Duplicate
ANC value (H2SO4/t)
Titrating with 0.1M HCl, in increments of 0.1 mLs every 1000 seconds
ANALYSIS REPORT: Created by Leigh Wills - ALS Sydney 2000
DATE COMPLETED:
SAMPLE TYPE:
No. of SAMPLES:
Sarah Gilmour
COMMENTS
ADDRESS:
Signatory
07 3243 [email protected] E-mail:
Australian Laboratory Services Pty Ltd (ABN 84 009 936 029)
STAFFORD QLD 4053 Facsimile:
Kinetic Net Acid Generation (NAG) Report
Batch: ES1907149
DATE RECEIVED:
26/11/2018Brisbane
8/03/2019
LABORATORY:
DATE SAMPLED:CLIENT: GHD PTY LTD2 SALAMANCA SQUARE
CONTACT:
Telephone:
EA011K: This method is not NATA accredited
ISSUING LABORATORY: ALS BRISBANE
Address: 2 Byth Street 07 3243 7222
HOBART TAS, AUSTRALIA 7000 20/03/2019
1Soil
Work Order : ES1907149 Client ID:
Sub Matrix Soil SoilClient Sample Identification 1 2018 bene combined tailings2018 bene combined tailings
Client Sample Identification 226/11/2018 26/11/2018
EA011-K: (A) Titration information
Time (mins) pH Temp pH Temp pH Temp
0 6.21 21.0 6.16 24.610 6.31 23.0 6.22 26.820 6.54 25.0 6.25 28.830 6.58 27.5 6.27 30.640 6.60 29.7 6.28 32.350 6.62 32.0 6.31 33.860 6.64 34.0 6.34 35.570 6.67 35.9 6.36 36.980 6.69 38.1 6.39 38.390 6.72 40.2 6.44 39.9100 6.76 42.5 6.51 41.4110 6.81 45.4 6.55 43.1120 6.87 49.2 6.59 45.3130 6.96 54.6 6.67 48.5140 7.12 63.1 6.76 52.8150 7.59 74.6 6.91 57.8160 8.42 69.8 7.24 72.2170 8.65 60.5 7.73 63.0180 8.70 54.0 8.50 57.5190 8.73 49.0 8.64 51.1200 8.75 45.0 8.70 46.4210 8.76 41.8 8.76 42.7220 8.78 39.3 8.80 39.6230 8.78 37.2 8.83 37.1240 8.79 35.3 8.85 35.3250 8.78 33.8 8.88 33.6260 8.75 32.6 8.92 32.1270 8.76 31.4 8.94 30.9280 8.75 30.3 8.96 30.0290 8.73 29.5 8.98 29.1300 8.73 28.9 9.00 28.4310 8.71 28.1 9.02 27.9320 8.71 27.6 9.04 27.3330 8.68 27.3 9.05 26.8340 8.67 26.8 9.07 26.5350 8.66 26.4 9.08 26.2360 8.65 26.2 9.08 26.2
Sample Date
GHD PTY LTD
ES19071491
ES19071491 Check
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5
10.010.511.011.512.012.513.013.514.0
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360
Tem
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ES1907149 - 1 (2018 bene combined tailings)Kinetic NAG
pH
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0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5
10.010.511.011.512.012.513.013.514.0
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360
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atu
re (
Cel
siu
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Time (minutes)
ES1907149 - 1 Check (2018 bene combined tailings)Kinetic NAG
pH
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0 0.00 True
Environmental
CERTIFICATE OF ANALYSISWork Order : Page : 1 of 6ES1909328
:: LaboratoryClient GHD PTY LTD Environmental Division Sydney
: :ContactContact Sarah Gilmour Andrew Epps
:: AddressAddress LEVEL 15, 133 CASTLEREAGH STREET
SYDNEY NSW, AUSTRALIA 2000
277-289 Woodpark Road Smithfield NSW Australia 2164
:Telephone ---- :Telephone +61 7 3552 8639
:Project 3219134 Date Samples Received : 27-Mar-2019 14:00
:Order number Date Analysis Commenced : 28-Mar-2019
:C-O-C number ---- Issue Date : 18-Apr-2019 18:26
Sampler : ----
Site :
Quote number : EN/005/18
4:No. of samples received
4:No. of samples analysed
This report supersedes any previous report(s) with this reference. Results apply to the sample(s) as submitted. This document shall not be reproduced, except in full.
This Certificate of Analysis contains the following information:
l General Comments
l Analytical Results
Additional information pertinent to this report will be found in the following separate attachments: Quality Control Report, QA/QC Compliance Assessment to assist with
Quality Review and Sample Receipt Notification.
SignatoriesThis document has been electronically signed by the authorized signatories below. Electronic signing is carried out in compliance with procedures specified in 21 CFR Part 11.
Signatories Accreditation CategoryPosition
Ivan Taylor Analyst Sydney Inorganics, Smithfield, NSW
Raymond Commodore Instrument Chemist Sydney Inorganics, Smithfield, NSW
Titus Vimalasiri Metals Teamleader Radionuclides, Fyshwick, ACT
R I G H T S O L U T I O N S | R I G H T P A R T N E R
2 of 6:Page
Work Order :
:Client
ES1909328
3219134:Project
GHD PTY LTD
General Comments
The analytical procedures used by the Environmental Division have been developed from established internationally recognized procedures such as those published by the USEPA, APHA, AS and NEPM. In house
developed procedures are employed in the absence of documented standards or by client request.
Where moisture determination has been performed, results are reported on a dry weight basis.
Where a reported less than (<) result is higher than the LOR, this may be due to primary sample extract/digestate dilution and/or insufficient sample for analysis.
Where the LOR of a reported result differs from standard LOR, this may be due to high moisture content, insufficient sample (reduced weight employed) or matrix interference.
When sampling time information is not provided by the client, sampling dates are shown without a time component. In these instances, the time component has been assumed by the laboratory for processing
purposes.
Where a result is required to meet compliance limits the associated uncertainty must be considered. Refer to the ALS Contact for details.
CAS Number = CAS registry number from database maintained by Chemical Abstracts Services. The Chemical Abstracts Service is a division of the American Chemical Society.
LOR = Limit of reporting
^ = This result is computed from individual analyte detections at or above the level of reporting
ø = ALS is not NATA accredited for these tests.
~ = Indicates an estimated value.
Key :
Gross Alpha and Beta Activity analyses are performed by ALS Fyshwick (NATA Accreditation number 992).l
LOR for gross alpha and beta in sample 4 raised due to the high amount of solid present.l
LOR for gross alpha and beta in sample raised due to the high amount of solid present.l
3 of 6:Page
Work Order :
:Client
ES1909328
3219134:Project
GHD PTY LTD
Analytical Results
------------2018 bene combined
tailings
ASLP PH 9
2018 bene combined
tailings
ASLP PH 5
Client sample IDSub-Matrix: ASLP LEACHATE
(Matrix: WATER)
------------26-Mar-2019 00:0026-Mar-2019 00:00Client sampling date / time
------------------------ES1909328-004ES1909328-001UnitLORCAS NumberCompound
Result Result ---- ---- ----
EA250: Gross Alpha and Beta Activity
0.96 <0.05 ---- ---- ----Bq/L0.05----Gross alpha
0.65 <0.10 ---- ---- ----Bq/L0.10----Gross beta activity - 40K
4 of 6:Page
Work Order :
:Client
ES1909328
3219134:Project
GHD PTY LTD
Analytical Results
----------------2018 bene combined
tailings
ALSP DI
Client sample IDSub-Matrix: DI WATER
(Matrix: WATER)
----------------26-Mar-2019 00:00Client sampling date / time
--------------------------------ES1909328-003UnitLORCAS NumberCompound
Result ---- ---- ---- ----
EA250: Gross Alpha and Beta Activity
<0.05 ---- ---- ---- ----Bq/L0.05----Gross alpha
<0.10 ---- ---- ---- ----Bq/L0.10----Gross beta activity - 40K
5 of 6:Page
Work Order :
:Client
ES1909328
3219134:Project
GHD PTY LTD
Analytical Results
--------2018 bene combined
tailings
ASLP PH 9
2018 bene combined
tailings
ALSP DI
2018 bene combined
tailings
ASLP PH 5
Client sample IDSub-Matrix: SOIL
(Matrix: SOIL)
--------26-Mar-2019 00:0026-Mar-2019 00:0026-Mar-2019 00:00Client sampling date / time
----------------ES1909328-004ES1909328-003ES1909328-001UnitLORCAS NumberCompound
Result Result Result ---- ----
EN60: ASLP Leaching Procedure
4.9 ---- 9.2 ---- ----pH Unit0.1----Extraction Fluid pH
5.0 ---- 9.5 ---- ----pH Unit0.1----Final pH
EN60: Bottle Leaching Procedure
---- 9.8 ---- ---- ----pH Unit0.1----Final pH
6 of 6:Page
Work Order :
:Client
ES1909328
3219134:Project
GHD PTY LTD
Analytical Results
----------------Hastings pilot plant
filtrate
Client sample IDSub-Matrix: WATER
(Matrix: WATER)
----------------26-Mar-2019 00:00Client sampling date / time
--------------------------------ES1909328-002UnitLORCAS NumberCompound
Result ---- ---- ---- ----
EA250: Gross Alpha and Beta Activity
<0.05 ---- ---- ---- ----Bq/L0.05----Gross alpha
<0.10 ---- ---- ---- ----Bq/L0.10----Gross beta activity - 40K
Technical File Note
HASTINGS TECHNOLOGY METALS LIMITED DOCUMENT NO: YGB-20-000-ENG-PRO-TCN-0001_Rev01
Page 1 of 4
SUBJECT: Mo and F levels in Recycled Process Water testwork
DATE: 17/5/2019
DOCUMENT NO. & REV: YGB-20-000-ENG-PRO-TCN-0001 Rev 01
AUTHOR: N Marriott – Principal Engineer – Beneficiation
SUMMARY
A review of the recycled process water quality was undertaken after queries from DWER on the tailings
leach testwork. Specifically Molybdenum (Mo) and Fluorine (F) levels in the tailings leach test were initially
high and then declined rapidly with flushing. The question was asked whether repeated contact with fresh
ore would result in Mo and F concentrations significantly above those seen in the tailings leach testwork.
Locked cycle testwork has been carried out to assess the water quality and impact on metallurgical
performance of recycled process water chemistry. Mo and F were not measured initially, however some
results were able to be measured in the last 3 cycles of the locked cycle testwork (out of a total of 15
cycles). TDS levels were around 2600 to 3100 mg/L, with associated Mo and F assays at 2-2.5 mg/L and
4-5mg/L respectively.
BACKGROUND
This technical filenote discussed water quality from testwork intended to simulate process water recycle
within this Yangibana Beneficiation flowsheet.
This is an interim report associated with the testwork, specifically discussing the deportment of elements
Mo and F queried by DWER during the works approval process.
TEST DETAILSThe Yangibana beneficiation flowsheet is in open circuit, with the tailings from each of the flotation stages
reporting to final tailings. The locked cycle testwork was designed to look at the recycle of water within the
process. The initial plan was to complete 8 rougher only cycles to produce the process water that would
then be tested on the full rougher and 4-stage cleaner circuit. However additional cycles were added in
order to optimise the reagent dose rates with the new water chemistry. The ore sample used for this
testwork was the 2016 blended pilot plant feed (sourced from the Bald Hill and Fraser’s mineralisation).
A total of 15 cycles have been completed in the locked cycle testwork. Regardless of cycle performance
the water from each test was recovered by adding the coagulation reagent proposed in the full scale
operation – lime. The supernatant was then decanted. Additional water was recovered by collecting the
filtrate from pressure filtration, in order to maximise the amount of recycled water available for subsequent
tests.
Technical File Note
HASTINGS TECHNOLOGY METALS LIMITED DOCUMENT NO: YGB-23-300-ENG-PRO-TCN-0001_Rev00
Page 2 of 4
Samples from each cycle were analysed for a limited suite of elements. F and Mo were added late in the
program to address the query from DWER.
RESULTS The results of water analysis from each cycle of testing are shown in Figure 1 below. This graph shows
the levels of Ca, Cl, Mg, Na, SiO2 and total dissolved solids (TDS) for the initial raw site water, as well as
water analysis at the end of each flotation test. TDS of the water rose rapidly from 1150mg/L in the raw
site water, up to a maximum of 3615 mg/L in the testwork. With Sodium (Na) being a major driver of TDS
levels. Sodium levels are being increased by the addition of sodium silicate and caustic soda (NaOH)
reagents in the process. Increased levels in the process water can be of assistance in the processing
circuit, acting as recycled reagents, reducing the amount of fresh caustic soda required by the process.
A more detailed analysis was complete on the final testwork sample from Test P, the results are shown in
Appendix A.
Figure 1 - Graph of recycled process water TDS and key dissolved element concentrations
Additional analyses of the water were undertaken after the levels of F and Mo in the tailings leach testwork
were questioned.
From the Tailings Characterisation Report (GCA Nov 2017) the observation was made that analysis of
TSF 1 and 2 slurry water indicates they are alkaline, brackish and likely to be enriched in fluorine (F) and
molybdenum (Mo) against the ANZECC Stock Quality Guideline (ANZECC, 2000). Pb was less than
Technical File Note
HASTINGS TECHNOLOGY METALS LIMITED DOCUMENT NO: YGB-23-300-ENG-PRO-TCN-0001_Rev00
Page 3 of 4
detection-limit in the slurry water despite elevated levels of Pb in TSF 1 and 2 solids. Radionuclides
concentrations in the TSF 1 and 2 Slurry Waters were below 1Bq/g and not considered radioactive.
Further Leach testing detailed in in “180621 - Yangibana Tailings Leach Study Report - R0” June 2018,
has suggested that the enrichments of Mo and F are temporary artefacts of the process water. These
enrichments rapidly decline with flushing. This indicates that the Mo and F elevations were largely due to
'operational time-scales' and are not a long term feature of the tailings leachate.
The question was raised regarding what level of Mo and F would be seen on multiple contacts between
fresh ore and recycled process water during the operation. Figure 2 below shows the results from 3 cycles
of testing, at the end of the testwork program. TDS levels were around 2600 to 3100 mg/L, with associated
Mo and F assays at 2-2.5 mg/L and 4-5mg/L respectively.
Figure 2 – Molybdenum and Fluorine analysis of recycled process water from last 3 cycles of testing
Note that no fresh water was added to the locked cycle testwork, however the current water modeling for
site indicates that in steady state the process will operate on a mix of 80:20 recycled water to fresh raw
water, with some water lost to the hydromet circuit, evaporation, water losses in the concentrate dryer and
to the settled solids in the TSF.
The leach testwork leachate Mo levels were 1.072 to 1.154 mg/L for TSF 1 liquor and 1.953 mg/L for TSF
2 liquor.
The leach testwork leachate F levels were 7-11mg/L for the tailings leach testing.
Technical File Note
HASTINGS TECHNOLOGY METALS LIMITED DOCUMENT NO: YGB-23-300-ENG-PRO-TCN-0001_Rev00
Page 4 of 4
APPENDIX A – DETAILLED WATER ANALYSIS (TEST P)
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix D – Seepage Analysis
Figure D-12-1 Seepage model arrangement
Figure D-12-2 Seepage model – Year 1
Figure D-12-3 Seepage model – Year 4
Figure D-12-4 Seepage model – Year 6
Figure D-12-5 Seepage model – Year 10
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134 |
Figure D-12-6 Seepage model – Year 15
Figure D-12-7 Seepage model – Year 100
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix EStability Analysis
SLOPE STABILITY ANALYSIS
1) END OF CONSTRUCTION - UNDRAINED CONDITIONS - DOWNSTREAM
2) END OF CONSTRUCTION - DRAINED CONDITIONS - DOWNSTREAM
3) END OF CONSTRUCTION - DRAINED CONDITIONS WITH Ru = 0.5 - DOWNSTREAM
4) END OF CONSTRUCTION- UNDRAINED CONDITIONS - UPSTREAM
5) END OF CONSTRUCTION- DRAINED CONDITIONS - UPSTREAM
6) END OF CONSTRUCTION - DRAINED CONDITIONS WITH Ru -UPSTREAM
7) TAILING – UNDRAINED CONDITIONS
8) TAILING - DRAINED CONDITIONS
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix FConsequence Category Assessment
Client NameDam NameDam ID. No. (If existing dam) X X X XStream NameDam Height (Metres) Crest RLEstimated Capacity at FSL (Megalitres) 5,500Location
Yangibana Beneficiation TSF
N/A11m
Yangibana
Min
or
Med
ium
Maj
or
Cat
astr
ophi
c
TOTAL INFRASTRUCTURE COSTS (costs are indicative only)Residential <10M YES . . .Commercial <10M YES . . .Community Infrastructure <10M YES . . .Dam replacement or repair cost <10M YES . . .
IMPACT ON DAM OWNER'S BUSINESSImportance to the business Essential to maintain supply . . YES .Effect on services provided by the owner Severe restictions would be applied for at least 1 yr . . YES .Effect on continuing credibility Severe widespread reaction . YES . .Community reaction and political implications Severe widespread reaction . YES . .Impact on financial viability Significant with considerable impact in the long term . YES . .Value of water in storage (assessed by the owner in relation to the business)
Can be absored in one financial year YES . . .
HEALTH and SOCIAL IMPACTSPublic health <100 people affected YES . . .Loss of service to the community <100 people affected YES . . .Cost of emergency management <1,000 person days YES . . .Dislocation of people <100 person months YES . . .Dislocation of businesses <20 business months YES . . .Employment affected <100 jobs lost YES . . .Loss of heritage Local facility YES . . .Loss of recreational facility Local facility YES . . .
NATURAL ENVIRONMENTArea of Impact <5km2 . YES . .Duration of Impact <1 (wet) year YES . . .Stock and Fauna Discharge from dambreak would not contaminate water
supplies used by stock and fauna.YES . . .
Ecosystems Discharge from dambreak would have short term impacts on ecosystems with natural recovery expected after 1 wet season. Remediation possible.
. YES . .
Rare and endangered fauna and flora Species exist but minimal damage expected. Recovery within one year.
YES . . .
NATURAL ENVIRONMENT damage and loss severity level
HIGHEST DAMAGE AND LOSS SEVERITY LEVEL
Population at Risk (PAR) ≥1-10PAR includes all those persons who would be directly exposed to flood waters within the dam break affected zone if they took no action to evacuate.
CONSEQUENCE CATEGORY =
Completed and Reviewed ByDate
MAJOR
MINOR
339.0 m
HEALTH and SOCIAL IMPACTS damage and loss severity level
MINOR
CONSEQUENCE CATEGORY ASSESSMENTSunny Day Failure Scenario
26/03/2019
MEDIUM
MAJOR
Tom Ridgway / Ben Hanslow
Damage and Loss Estimate
Severity Level
Note 1: With a PAR in excess of 100, it is unlikely Damage will be minor. Similarly with a PAR in excess of 1,000 it is unlikely Damage will be classified as Medium.
Note 2: Change to 'High C' where there is the potential of one or more lives being lost. The potential for loss of life is determined by the charateristics of the flood area, particularly the depth and velocity of flow.
Reasons for recommending the consequence category (refer ANCOLD "Guidelines on the Consequence Categories for Dams", 2012) which MUST include comments on PAR, buildings, roads, other infrastructure and natural environment downstream of the dam and the potential impacts arising from a dambreak (NOTE: Provide photographs to support reasons):— The costs for the infrastructure and dam replacement and clean-up costs would be likely to exceed 10 million dollars but be less than 100 million dollars giving a medium level of damage to ANCOLD.— The impact of a sunny day failure failure on the dam owners business is ‘Major’ as the operation of the tailings dam is critical to the ongoing extraction and processing of the rare earth minerals and would lead to major economic impacts.— The impact of a dam failure on health and social impacts is minor due to the regional location of the dam.— The environmental impacts of a sunny day failure of the embankment is minor due to the benign nature of the material and low expected radiological impacts.— The environmental impacts of a flood loading failure scenario are considered to be moderate due to the benign nature of the material and the lack of expected long-term effects of the material within the surrounding environment.— Population at Risk (PAR) in flow path in case of failure would be limited to itinerants given no current permanent residences or mine facilities downstream. However, flooding could affect the site haul road. Arguably the PAR could be <1 but conservatively between 1 and 10.
HIGH C
TOTAL INFRASTRUCTURE COSTS severity level
IMPACT ON DAM OWNER'S BUSINESS damage and loss severity level
Client NameDam NameDam ID. No. (If existing dam) X X X XStream NameDam Height (Metres) Crest RLEstimated Capacity at FSL (Megalitres) 5,500Location
Yangibana Beneficiation TSF
N/A11 m
Yangibana
Min
or
Med
ium
Maj
or
Cat
astr
ophi
c
TOTAL INFRASTRUCTURE COSTS (costs are indicative only)Residential <10M YES . . .Commercial <10M YES . . .Community Infrastructure <10M YES . . .Dam replacement or repair cost <10M YES . . .
IMPACT ON DAM OWNER'S BUSINESSImportance to the business Restrictions needed during dry periods YES . . .Effect on services provided by the owner Minor difficulties in replacing services YES . . .Effect on continuing credibility Some reaction but short lived YES . . .Community reaction and political implications Some reaction but short lived YES . . .Impact on financial viability Able to absorb in 1 financial year YES . . .Value of water in storage (assessed by the owner in relation to the business)
Can be absored in one financial year YES . . .
HEALTH and SOCIAL IMPACTSPublic health <100 people affected YES . . .Loss of service to the community <100 people affected YES . . .Cost of emergency management <1,000 person days YES . . .Dislocation of people <100 person months YES . . .Dislocation of businesses <20 business months YES . . .Employment affected <100 jobs lost YES . . .Loss of heritage Local facility YES . . .Loss of recreational facility Local facility YES . . .
NATURAL ENVIRONMENTArea of Impact <5km2 . YES . .Duration of Impact <1 (wet) year YES . . .Stock and Fauna Discharge from dambreak would not contaminate water
supplies used by stock and fauna.YES . . .
Ecosystems Discharge from dambreak is not expected to impact on ecosystems. Remediation possible.
YES . . .
Rare and endangered fauna and flora Species exist but minimal damage expected. Recovery within one year.
YES . . .
NATURAL ENVIRONMENT damage and loss severity level
HIGHEST DAMAGE AND LOSS SEVERITY LEVEL
Population at Risk (PAR) <1PAR includes all those persons who would be directly exposed to flood waters within the dam break affected zone if they took no action to evacuate.
CONSEQUENCE CATEGORY =
Completed and Reviewed ByDate
CONSEQUENCE CATEGORY ASSESSMENTEnvironmental Spill Scenario
339.0 m
Damage and Loss Estimate
Severity Level
TOTAL INFRASTRUCTURE COSTS severity level MINOR
IMPACT ON DAM OWNER'S BUSINESS damage and loss severity level MINOR
HEALTH and SOCIAL IMPACTS damage and loss severity level MINOR
MEDIUM
MEDIUM
LOW
Note 1: With a PAR in excess of 100, it is unlikely Damage will be minor. Similarly with a PAR in excess of 1,000 it is unlikely Damage will be classified as Medium.
Note 2: Change to 'High C' where there is the potential of one or more lives being lost. The potential for loss of life is determined by the charateristics of the flood area, particularly the depth and velocity of flow.
Reasons for recommending the consequence category (refer ANCOLD "Guidelines on the Consequence Categories for Dams", 2012) which MUST include comments on PAR, buildings, roads, other infrastructure and natural environment downstream of the dam and the potential impacts arising from a dambreak (NOTE: Provide photographs to support reasons):The Environmental Spill Consequence Category for the Beneficiation TSF has been assessed as Low, due to the benign nature of tailings, and low environmental risk due to lack of radionuclides and low metals concentration in the leachate.
Tom Ridgway / Ben Hanslow26/03/2019
Client Name YangibanaDam Name Hydromet TSFDam ID. No. (If existing dam) X X X XStream Name N/ADam Height (Metres) 9m Crest RLEstimated Capacity at FSL (Megalitres) 1,200Location Yangibana
Min
or
Med
ium
Maj
or
Cat
astr
ophi
c
TOTAL INFRASTRUCTURE COSTS (costs are indicative only)Residential $10M - $100M . YES . .Commercial <10M YES . . .Community Infrastructure <10M YES . . .Dam replacement or repair cost <10M YES . . .
IMPACT ON DAM OWNER'S BUSINESSImportance to the business Essential to maintain supply . . YES .Effect on services provided by the owner Severe restictions would be applied for at least 1 yr . . YES .Effect on continuing credibility Severe widespread reaction . YES . .Community reaction and political implications Severe widespread reaction . YES . .Impact on financial viability Able to absorb in 1 financial year YES . . .Value of water in storage (assessed by the owner in relation to the business)
Can be absored in one financial year YES . . .
HEALTH and SOCIAL IMPACTSPublic health <100 people affected YES . . .Loss of service to the community <100 people affected YES . . .Cost of emergency management <1,000 person days YES . . .Dislocation of people <100 person months YES . . .Dislocation of businesses <20 business months YES . . .Employment affected <100 jobs lost YES . . .Loss of heritage Local facility YES . . .Loss of recreational facility Local facility YES . . .
NATURAL ENVIRONMENTArea of Impact <1km2 YES . . .Duration of Impact <1 (wet) year YES . . .Stock and Fauna
Discharge from dambreak would contaminate water supplies used by stock and fauna. Health impacts not expected.
. YES . .
Ecosystems Discharge from dambreak would have short term impacts on ecosystems with natural recovery expected after 1 wet season. Remediation possible.
. YES . .
Rare and endangered fauna and flora Species exist with losses expected to be recovered over a number of years.
. YES . .
NATURAL ENVIRONMENT damage and loss severity level
HIGHEST DAMAGE AND LOSS SEVERITY LEVEL
Population at Risk (PAR) ≥1-10PAR includes all those persons who would be directly exposed to flood waters within the dam break affected zone if they took no action to evacuate.
CONSEQUENCE CATEGORY =
Completed and Reviewed ByDate
MAJOR
MINOR
341.0 m
HEALTH and SOCIAL IMPACTS damage and loss severity level
MEDIUM
CONSEQUENCE CATEGORY ASSESSMENTSunny Day Failure Scenario
26/03/2019
MEDIUM
MAJOR
Tom Ridgway / Ben Hanslow
Damage and Loss Estimate
Severity Level
Note 1: With a PAR in excess of 100, it is unlikely Damage will be minor. Similarly with a PAR in excess of 1,000 it is unlikely Damage will be classified as Medium.
Note 2: Change to 'High C' where there is the potential of one or more lives being lost. The potential for loss of life is determined by the charateristics of the flood area, particularly the depth and velocity of flow.
Reasons for recommending the consequence category (refer ANCOLD "Guidelines on the Consequence Categories for Dams", 2012) which MUST include comments on PAR, buildings, roads, other infrastructure and natural environment downstream of the dam and the potential impacts arising from a dambreak (NOTE: Provide photographs to support reasons):— The costs for infrastructure and dam replacement and repair costs are estimated to be below 10 million dollars giving a low level of impact to ANCOLD.— The impact of a sunny day failure on the dam owners business is ‘Major’ as the operation of the tailings dam is critical to the ongoing extraction and processing of the lithium.— The impact of a dam failure for sunny day loading on health and social impacts is minor due to the regional location of the dam.— The environmental impacts of a sunny day failure of the embankment is major.— The environmental impacts of a flood loading failure scenario are considered to be major due to the nature of the material and the lack of expected long-term effects of the material within the surrounding environment.— Population At Risk (PAR) in flow path in case of failure would be limited to itinerants given no current permanent residences or mine facilities downstream. However, flooding could affect the site haul road. Arguably the PAR could be <1 but conservatively between 1 and 10.
HIGH C
TOTAL INFRASTRUCTURE COSTS severity level
IMPACT ON DAM OWNER'S BUSINESS damage and loss severity level
Client Name YangibanaDam Name Hydromet TSFDam ID. No. (If existing dam) X X X XStream Name N/ADam Height (Metres) 9 m Crest RLEstimated Capacity at FSL (Megalitres) 1,200Location Yangibana
Min
or
Med
ium
Maj
or
Cat
astr
ophi
c
TOTAL INFRASTRUCTURE COSTS (costs are indicative only)Residential <10M YES . . .Commercial <10M YES . . .Community Infrastructure <10M YES . . .Dam replacement or repair cost <10M YES . . .
IMPACT ON DAM OWNER'S BUSINESSImportance to the business Restrictions needed during peak days and peak hour . YES . .Effect on services provided by the owner Minor difficulties in replacing services YES . . .Effect on continuing credibility Some reaction but short lived YES . . .Community reaction and political implications Some reaction but short lived YES . . .Impact on financial viability Able to absorb in 1 financial year YES . . .Value of water in storage (assessed by the owner in relation to the business)
Can be absored in one financial year YES . . .
HEALTH and SOCIAL IMPACTSPublic health <100 people affected YES . . .Loss of service to the community <100 people affected YES . . .Cost of emergency management <1,000 person days YES . . .Dislocation of people <100 person months YES . . .Dislocation of businesses <20 business months YES . . .Employment affected <100 jobs lost YES . . .Loss of heritage Local facility YES . . .Loss of recreational facility Local facility YES . . .
NATURAL ENVIRONMENTArea of Impact <1km2 YES . . .Duration of Impact <1 (wet) year YES . . .Stock and Fauna
Discharge from dambreak would contaminate water supplies used by stock and fauna with contaminant uptake.
. YES .
Ecosystems Discharge from dambreak would have short term impacts on ecosystems with natural recovery expected after 1 wet season. Remediation possible.
. YES . .
Rare and endangered fauna and flora Species exist but minimal damage expected. Recovery within one year.
YES . . .
NATURAL ENVIRONMENT damage and loss severity level
HIGHEST DAMAGE AND LOSS SEVERITY LEVEL
Population at Risk (PAR) <1PAR includes all those persons who would be directly exposed to flood waters within the dam break affected zone if they took no action to evacuate.
CONSEQUENCE CATEGORY =
Completed and Reviewed ByDate
CONSEQUENCE CATEGORY ASSESSMENTEnvironmental Spill Scenario
341.0 m
Damage and Loss Estimate
Severity Level
TOTAL INFRASTRUCTURE COSTS severity level MINOR
IMPACT ON DAM OWNER'S BUSINESS damage and loss severity level MEDIUM
HEALTH and SOCIAL IMPACTS damage and loss severity level MINOR
MAJOR
MAJOR
SIGNIFICANT
Note 1: With a PAR in excess of 100, it is unlikely Damage will be minor. Similarly with a PAR in excess of 1,000 it is unlikely Damage will be classified as Medium.
Note 2: Change to 'High C' where there is the potential of one or more lives being lost. The potential for loss of life is determined by the charateristics of the flood area, particularly the depth and velocity of flow.
Reasons for recommending the consequence category (refer ANCOLD "Guidelines on the Consequence Categories for Dams", 2012) which MUST include comments on PAR, buildings, roads, other infrastructure and natural environment downstream of the dam and the potential impacts arising from a dambreak (NOTE: Provide photographs to support reasons):The Environmental Spill Consequence Category for the Hydromet TSF has been assessed as Significant due to the increased environmental risk resulting from a spill due to the increased concentration of Magnesium Sulphate and the concentration of radionuclides within the material.
Tom Ridgway / Ben Hanslow26/03/2019
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix G Environmental Benefits Summary Table
Environmental Risk Comparative Comments (FS Design vs Refined Design)
Site Location and Land Clearing
The disturbed footprint location remains unchanged for the refined concept design.
Slightly reduced clearing requirement associated with proposed refined design (See Figure 1). Any external borrow would likely be smaller for the refined design due to lesser clay/earthworks volumes associated with building the refined design.
Refined design embankments have the same or better setback to existing watercourses. (See Figure 2)
Dam Height and Failure Consequence Category (ANCOLD 2012)
RWP
RWP is eliminated from refined concept design (was Significant Consequence Category in FS design)
TSF1 (now combined with TSF2 as the Beneficiation TSF)
For the refined concept design, TSF1 perimeter embankment height is kept consistent with the FS design and ANCOLD Consequence Category is unchanged (Significant). Combining TSF1/2 does not increase the failure consequences.
TSF2
TSF2 is likely eliminated from preferred concept design (was Significant Consequence Category in FS design)
TSF3
The refined design for the Hydromet TSF that incorporates both TSF3 and Evaporation Pond has a reduced embankment height and similar or lesser consequences of failure/spill due to reduced height of tailings and ability to spill into Beneficiation TSF.
Evaporation Pond
For the refined concept design, the Evaporation Pond is eliminated (was Significant Consequence Category in FS Design)
Dam Spill Risk RWP/TSF1
In the FS design, the RWP was designed to contain run-off from TSF1 catchment and designed to hold a 1:100 AEP 72hr flood event prior to spill. For the refined concept, the RWP is not required and the decant pond within TSF1 has significant additional stormwater storage capacity (relative to FS RWP design) and hence overall significantly reduced risk of spill to the environment.
TSF2
In the FS design, TSF2 was designed to store a 1:100 AEP 72hr flood plus freeboard, but no emergency spillway provided (hence small risk of overtopping/failure if poorly managed or extreme flood occurs).
The refined concept combines Bene plant tailings into single stream and hence eliminates TSF2 from the design by combining with TSF1.
TSF3
In the FS design, TSF3 was designed to store a 1:100 AEP 72hr flood plus freeboard, but no emergency spillway provided. The refined concept allows the same flood storage on TSF3 but also includes an emergency spillway for containment of any spill within the capacity of Beneficiation TSF pond (i.e. no environmental release). The emergency spillway also eliminates the risk of overfilling and overtopping.
Evaporation Pond
Environmental Risk Comparative Comments (FS Design vs Refined Design)
The Evaporation Pond is eliminated from proposed refined concept (now combined with TSF3 and has emergency spillway into TSF1 decant pond)
Geotechnical Stability and Dam Failure Risk
RWP
The RWP dam failure risk is eliminated in refined concept.
TSF1
The refined concept design proposes conventional perimeter discharge. An Operations Manual will be developed requiring a central decant pond to be maintained with resulting low phreatic surface at perimeter embankment. This improves geotechnical stability and reduces piping risk (relative to CDF proposed in the FS design which relies on water ponding/drainage alongside the perimeter embankment).
TSF2
The feasibility study concept design proposes a 10 m high embankment with upstream clay zone and no filters. Ponding water against embankments means that piping is a plausible risk of dam failure/loss of containment.
The refined concept design eliminates TSF2 risk.
TSF3
The FS concept design proposes a 10 m high turkey’s nest embankment with a geocomposite lining system. The refined design proposes a similar high standard lining system, but better uses the natural topography resulting in significantly reduced tailings height and therefore overall lower risk of dam failure/loss of containment.
Seepage and Groundwater Risk
The overall TSF domain footprint is unchanged and situated on similar foundation conditions (i.e. similar for FS and refined concept). The geology comprises in-situ sandy clays overlying granite at shallow depth.
The refined design eliminates the need for the Return Water Pond which reduces risk posed by seepage impacting the watercourse at the toe of the dam (i.e. reduces risk of F and Mo concentrations in watercourse exceeding guidelines for stock drinking water).
Conventional perimeter discharge of thickened tailings allows small decant pond in Beneficiation TSF to be positioned centrally which minimises the risk of downstream seepage expression (relative to FS design). The development of wide desiccated beaches upstream of the Beneficiation TSF embankment mean that seepage risk is reduced in the proposed refined design.
TSF2 is eliminated in the proposed refined concept. Given the geochemistry similarities of TSF1 and TSF2 tailings, combining of the tailings is non-consequential and should reduce seepage due to eliminating a “wet” TSF for the proposed arrangement.
A high standard lining system is proposed for TSF3 in both the FS and refined concept design Hydromet TSF (i.e. same level of seepage mitigation is proposed).
Design maintains monitoring systems to allow early intervention prior to impact being caused.
Beach Slopes and Tailings Capacity/Beach Freeboard
The refined concept eliminates operational risk associated with Central Thickened Discharge (CTD) in TSF1. CTD can be very sensitive to thickener performance. Rather than rely on CTD, the proposed alternative arrangement for the Beneficiation TSF allows for perimeter tailings discharge via spigots. This removes the risks of flatter than expected beach slopes resulting in insufficient storage capacity during operations and potential overfilling of the TSF. Also, flattened beach slopes with CTD could result in significantly higher than expected
Environmental Risk Comparative Comments (FS Design vs Refined Design)
embankment heights and therefore greater geotechnical risk (relative to proposed refined design where embankment heights are more predictable due to less reliance on steep beach slope).
The refined concept uses perimeter beaching to control where the pond develops and ensures no pond on wall i.e. achieves central pond further set-back from watercourses and low Ksat tailings minimise seepage into foundation.
At closure a wide channel is excavated to ensure pond does not remain post closure. In the lead up closure, tailings discharge would adopt elements of CTD to maximise tails capacity and achieve suitable shedding surface with suitable network of drains. i.e. no change in philosophy.
Dust (including dust with elevated radiation levels)
Refined design combines TSF 3/Evaporation Pond into the Hydromet TSF. This reduces dusting risk in TSF3 that doesn’t rely on top-up water being pumped from a separate Evaporation Pond.
Flatter tailings beach slopes can be accommodated in the Beneficiation TSF using perimeter discharge method. This allows the combining of all Bene plant tailings streams for discharge into a combined TSF. Doing so further reduces the risk of dusting in the combined TSF1/2.
Surface Water Management
Refined design has less reliance on diversion of surface water run-off from TSF1. Overall the refined design has simplified water management which reduces risk of loss of containment.
See Figure 3 and 4
FS Design
The CTD option requires significant drainage to be excavated and managed around the full perimeter of the TSF. The actual location of the required diversion channel/s will depend on the beach slope achieved and the channel will need to be relocated and managed as the TSF beach expands. This will need to be carefully managed to ensure that the channel remains free draining. The unlined channel would also be an additional seepage source. It is also noted that water ponds on the upstream face of the perimeter embankment associated with the drainage path to the decant pond. The embankment design includes a relatively narrow clay zone and no filters – while piping risk is low, it still remains a plausible failure mode for the FS design.
Refined Design
The refined concept uses perimeter beaching to control where the pond develops and ensures no pond on wall (hence extremely low piping risk). 3 separate decant ponds are reduced to 1 single pond, hence eliminating risks of transferring water between ponds (pipe burst, channel blockage, erosion etc). Developing a well formed beach around the perimeter will require carefully management – but is well proven where mines manage responsibly. At closure a wide channel is excavated to ensure pond does not remain post closure. In the lead up to closure, tailings discharge would adopt elements of CTD to maximise tails capacity and achieve suitable shedding surface with suitable network of drains.
Closure Closure concepts, slopes and materials have not been altered.
Elimination of the standalone Evaporation Pond from the design arrangement reduces the rehabilitation liability associated with removing salt accumulation at closure which may be difficult to achieve in practice.
Pipe leakage / spills Risks are similar and manageable.
Figure 1 Comparative Disturbed Footprint
Figure 2 Comparative Embankments
Figure 3 Original Feasibility Study Design – Water Management Requirements
Figure 4 Refined Concept Design, Combined TSF with conventional perimeter discharge to form beaches and control pond location – no diversion channels required to contain TSF run-off
GHD | Report for Hastings Technology Metals Ltd - Yangibana TSF Design Development, 3219134
Appendix HExample Geosynthetic Liner Specification
The Client TSF xxx
Geosynthetic and Lining Specification
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification i
Table of contents 1. Introduction .................................................................................................................................... 1
1.1 General ................................................................................................................................ 1
1.2 Definitions ............................................................................................................................ 1
1.3 Lines of communication ....................................................................................................... 2
1.4 Materials .............................................................................................................................. 2
1.5 Sequencing and scheduling ................................................................................................. 2
1.6 Submittals ............................................................................................................................ 2
1.7 Construction quality control testing ...................................................................................... 4
1.8 Construction quality assurance ............................................................................................ 4
1.9 Work method statements ..................................................................................................... 5
1.10 Survey requirements ............................................................................................................ 6
1.11 Witness and hold points ....................................................................................................... 6
1.12 Works as Executed Drawings .............................................................................................. 7
2. PE geomembrane .......................................................................................................................... 8
2.1 General ................................................................................................................................ 8
2.2 Standards ............................................................................................................................. 8
2.3 Submittals ............................................................................................................................ 9
2.4 Manufacturer’s quality control ............................................................................................ 11
2.5 Manufacturer’s quality assurance ...................................................................................... 12
2.6 Material .............................................................................................................................. 12
2.7 Roll and sample identification ............................................................................................ 14
2.8 Delivery, storage and handling .......................................................................................... 14
2.9 Preparation of receiving surface ........................................................................................ 15
2.10 Installation .......................................................................................................................... 16
2.11 Weld trial ............................................................................................................................ 20
2.12 Trial seams ........................................................................................................................ 21
2.13 Field seam sampling and testing ....................................................................................... 21
2.14 Electrical leak location survey ............................................................................................ 24
2.15 Defects and repairs ............................................................................................................ 24
2.16 Acceptance ........................................................................................................................ 25
Pre-selection submittal form – geosynthetics .............................................................................. 28
Delivery submittal form – geosynthetics ...................................................................................... 30
Installation submittal form – geosynthetics .................................................................................. 32
Figure index Figure 1-1 Lines of communication ....................................................................................................... 2
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification ii
Table index Table 1-1 Independent sample size and frequency schedule ............................................................. 5
Table 1-2 Survey requirements ............................................................................................................ 6
Table 1-3 Witness and hold points ....................................................................................................... 7
Table 2-1 Acceptance criteria – PE geomembrane ........................................................................... 13
Table 2-2 Destructive seam testing requirements ............................................................................. 22
Table 2-3 Non-destructive seam testing requirements ...................................................................... 22
Table 2-4 Air pressure test schedule ................................................................................................. 23
Appendices Appendix A – Schedule of work method statements
Appendix B – Example submittal forms
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 1
1. Introduction 1.1 General
This Specification contains the requirements for materials and procedures to be implemented
for the construction of TSF xxx Lining Works (the Works) at xxx (the site) and must be read in
conjunction with the other Contract Documents.
Where the Specification and any other Contract Documents do not agree, the Contractor shall
seek clarification from the Manager.
1.2 Definitions
The Definitions described in the Contract Documents apply to this document. The following
additional terms used in this Specification shall have the meanings ascribed to them below
unless the context otherwise requires:
‘Contract Drawings’ – The construction drawings which form part of the Contract Documents
‘Contract Documents’ – The documents which form the Contract
‘Contractor’ – A company or person with a formal contract to do a specific job – supplying labour
and/or materials and providing and overseeing staff as required
‘Contractor’s Independent Testing Firm’ – Independent testing firm(s) engaged by the
Contractor to conduct construction quality control (CQC) testing
‘Construction Quality Assurance (CQA) Engineer’ – Suitably qualified professional responsible
for administering the CQA requirements for the Works
‘Construction Quality Assurance (CQA) Engineer’s Independent Testing Firm’ – Independent
testing firm(s) engaged by the CQA Engineer to conduct construction quality assurance testing
‘Construction Quality Assurance (CQA) Plan’ – Plan forming part of the Contract Documents,
describing the construction quality assurance requirements for the Works
‘Field Crew Foreman’ – Foreman for the Geosynthetic Installer’s field crew, as defined by the
Contractor
‘Geosynthetic’ – Synthetic material (man-made plastic and fabric) used in geotechnical and
construction applications
‘Geosynthetic Installer’ – Firm subcontracted by the Contractor to complete the installation of
geosynthetic for the Works
‘Manager’ – The person who is managing the Contract on behalf of the Owner and who supplies
directions to the Contractor and to whom the Contractor refers in all matters.
‘MARV’ – Minimum average roll value – calculated as per GRI White Paper #10, The Dual
Roles for Using MARV (http://www.geosynthetic-institute.org/papers/paper10.pdf)
‘MaxARV’ – Maximum average roll value – calculated as per GRI White Paper #10, The Dual
Roles for Using MARV (http://www.geosynthetic-institute.org/papers/paper10.pdf)
‘Owner’ – xxx
‘PE’ – Polyethylene
‘Regulatory Authority’ – Authority responsible for licencing the Works
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 2
‘Seaming Crew’ – Crew responsible for the seaming activities performed by the Geosynthetic
Installer, as defined by the Contractor
‘Seaming Foreman’ – Foreman for the seaming activities performed by the Geosynthetic
Installer, as defined by the Contractor
‘Specification’ – This document
‘Work under the Contract' – The work which the Contractor is or may be required to execute
under the Contract and includes variations, remedial work, constructional plant and temporary
works
‘Works’ – The whole of the work to be executed in accordance with the Contract, including
variations provided for by the Contract, which by the Contract is to be handed over to the Owner
‘Works Area’ – As shown on the Contract Drawings.
1.3 Lines of communication
The lines of communication for the Works are illustrated in Figure 1-1. The Manager shall be the
main point of liaison between the Contractor and the CQA Engineer, as well as the Contractor
and the Owner.
Figure 1-1 Lines of communication
1.4 Materials
The Contractor shall be responsible for the sourcing, delivery, storage, preparation, handling
and installation of all materials, except as modified in individual sections of this Specification.
Material and installation specifications are included in the individual sections of this Specification
for each material type.
1.5 Sequencing and scheduling
The Contractor shall be responsible for sequencing the installation of all materials, including
surveys, testing and field trials.
In general, installation sequencing shall proceed from higher elevations to lower elevations to
prevent precipitation runoff from flowing into and/or below installed products.
Individual components shall not be covered with the subsequent component until the underlying
component has been accepted by the Manager.
1.6 Submittals
Submittals for each material are included in the individual chapters of this Specification.
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 3
The following pre-qualification submittals are required to be submitted by the Contractor at least
10 working days prior to construction for approval by the Manager.
1.6.1 Pre-qualification of the Geosynthetic Installer
Prior to construction, the Contractor shall provide a list documenting completed facilities for
which the Geosynthetic Installer has completed the installation of a geosynthetic lining system
similar to this Specification. For each facility, the following information shall be provided:
The name and purpose of the facility, its location, and the date of installation
The name of the owner, project manager, designer, manufacturer, and fabricator (if any)
If requested, the name and telephone number of a reference contact at the facility who can
discuss the project
The name and qualifications of the supervisor(s) of the installer’s crew(s)
The type(s) of seaming, patching, and tacking equipment
Any available information on the performance of the geosynthetic lining system at the
facility.
The Contractor shall also provide:
Certification indicating an approval or licence from the proposed geosynthetic
manufacturers for the Contractor to install the manufacturer’s materials
Certification that the Geosynthetic Installer’s Field Crew Foreman has a minimum of 200
hectares of actual geosynthetic installation experience and a minimum of 100 hectares of
supervisory experience for geosynthetic installation on a minimum of 10 different projects
Certification that the Geosynthetic Installer’s Seaming Foreman is an International
Association of Geosynthetic Installer’s Certified Welding Technician and has a minimum of
100 hectares of actual geosynthetic seaming experience and a minimum of 50 hectares of
supervisory experience during the seaming of geosynthetic materials
Certification that each individual on the Geosynthetic Installer’s Seaming Crew has a
minimum of 10 hectares of geosynthetic seaming experience and a minimum of 5 hectares
of seaming experience with geosynthetics similar to this Specification.
1.6.2 Pre-qualification of the Contractor’s Independent Testing Firm
Prior to construction, the Contractor shall provide a listing of qualifications for the proposed
Contractor’s Independent Testing Firms(s) and its key personnel who shall perform the work
described in this Specification. The Contractor’s Independent Testing Firms(s) shall be National
Association Testing Authorities (NATA) accredited and proof of accreditation shall be
maintained throughout the duration of the Works.
A listing of testing apparatus and testing standards typically performed by the testing firm shall
be provided along with a letter stating that the testing firm is independent and has no financial
interest in the Contractor, the Geosynthetic Installer or any of the manufacturers/suppliers that
are providing materials for the Works.
1.6.3 Works program
The Contractor shall prepare a program for the Works. The program shall encompass all
phases of the Works. The Contractor shall submit a draft of the program to the Manager for
review and approval at least 10 working days prior to construction. The Contractor shall not
undertake any works on the site until approval for such is given by the Manager. The program
shall include regular progress meetings with the Manager.
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1.6.4 Procurement plan
Prior to construction, the Contractor shall provide a procurement plan which considers each
material to be supplied for the Works. For each material, the plan shall consider:
Material sources and relevant quantities from each source
Estimated timeframe for pre-qualification testing, provision of results and subsequent
approval to deliver to site
Estimated timeframe for delivery of material on-site
Estimated timeframe for independent conformance testing, provision of results and
subsequent approval for use (where required, refer Section 1.8.1).
The procurement plan shall align with the Works program, including installation timeframes.
1.6.5 Construction quality control plan
The Contractor shall prepare and implement a CQC Plan for the Works, and the plan shall
address all quality considerations identified or outlined in this Specification. The CQC plan shall
incorporate, as necessary, field testing, field verification, manufacturer’s certifications and
quality control testing at the manufacturing plant, to demonstrate that all Works comply with this
Specification. The CQC plan shall also demonstrate how construction will occur and the
methods by which the materials will be supplied, placed and tested to ensure compliance with
this Specification.
Works shall not commence until the CQC plan has been approved by the Manager.
The Owner may, at its discretion, audit the Contractor’s implementation of the CQC plan. The
Contractor shall co-operate with all such auditing.
1.7 Construction quality control testing
All construction quality control (CQC) testing shall be arranged by the Contractor and shall be
carried out by the Contractor’s Independent Testing Firm. The cost of CQC testing shall be
borne by the Contractor. Unless noted otherwise, copies of all test results shall be sent to the
Manager as soon as available but in any event within two days of becoming available. The
minimum testing frequencies shall be as nominated within this Specification.
At any stage throughout the Works, the Manager may arrange for independent testing and/or
surveying to be carried out. If that testing reveals that any works are found to be not compliant
with the requirements of this Specification and the Contract Drawings, the Contractor shall
undertake rectification of the non-compliant items and conduct re-testing in accordance with this
Specification. All costs of undertaking such rectification work and re-testing shall be borne by
the Contractor.
1.8 Construction quality assurance
A Construction Quality Assurance (CQA) Plan has been developed in conjunction with this
Specification and shall be implemented by the Owner to verify that the Works are undertaken in
a manner that meets the requirements of the Contract Documents.
The Owner shall engage an independent organisation (the CQA Engineer), under contract to
the Owner, who shall facilitate the requirements of the CQA Plan. This shall include
independent CQA monitoring, observation, testing and documentation on behalf of the Owner.
The Contractor shall cooperate fully with the Manager and all representatives of the CQA
Engineer during any independent CQA sampling, testing, and certification and shall ensure, at
all times, safe access to the Works for the purpose of monitoring, observation, and CQA
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implementation. This shall include sampling of geosynthetic materials by the Geosynthetic
Installer under the supervision of the CQA Engineer.
1.8.1 Independent conformance testing
The CQA Engineer shall arrange for independent conformance testing of the materials used in
the Works, in accordance with the CQA Plan, to assure conformance with this Specification.
Samples shall be collected at locations designated by the CQA Engineer and all independent
conformance sampling shall be witnessed by the CQA Engineer. Where sampling of
geosynthetics is necessary, the sampling shall be undertaken by the Geosynthetic Installer from
the relevant materials for the independent conformance testing of the material. The Contractor
shall make a suitable allowance for this testing within their construction program.
The sample frequency shall be in accordance with Table 1-1. The table also identifies the
indicative sample size. The sample sizes shall be confirmed by the CQA Engineer prior to
construction. Sampling shall include the first and last roll. The specified frequency assumes all
rolls are from a single manufacturing run. If rolls are from different manufacturing runs then the
frequency shall be applied to each manufacturing run. The test frequency for all rolls where, in
the opinion of the CQA Engineer, the manufacturing run cannot be identified shall be every roll
for all test types. Samples shall not be taken from the outer wrap of the roll.
Table 1-1 Independent sample size and frequency schedule
Material Indicative size Frequency PE geomembrane 1 metre by roll width 1 per 5,000 m2
As a minimum, a period of 6 weeks shall be allowed for from the completion of on-site sampling
of all geosynthetic materials on-site to the receipt of independent conformance testing results
and subsequent approval/rejection of the materials for use. This shall be confirmed by the CQA
Engineer prior to construction.
If a sample records a non-conforming test result, it may be re-tested. If it passes this retest, both
results shall be provided in the laboratory report from the relevant independent testing firm. If
the retest produces a non-conforming test result, the Contractor shall remove and replace all
rolls between the sampled roll and the nearest conforming rolls either side (based on the
production order of the rolls). The Contractor may, by testing and verification of these
intermediate rolls, reduce the range of rolls to be removed in this way. Such additional testing
shall be for the full range of specified tests, not just the test or property which yielded a failure.
In the event of discrepancies between the CQA Engineer’s test results and the Contractor’s test
results, the Contractor shall be responsible for arranging a third independent testing firm to
verify the test results.
Any replacement material shall receive the independent conformance testing in accordance with
the CQA Plan.
1.9 Work method statements
Prior to the commencement of each type of work, the Contractor shall submit to the Manager
work method statements that detail how the work is to be carried out and the plant and
equipment proposed.
The Contractor shall submit such work method statements to the Manager at least 5 working
days prior to undertaking any work addressed by the work method statement.
The Manager may reject the submitted work method statement if, in the opinion of the Manager,
the statement does not comply with the Specification or any other Contract Documents provided
to the Contractor prior to or during construction.
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Where a work method statement is rejected the Contractor shall revise and resubmit the
statement. No work addressed by the work method statement shall be undertaken by the
Contractor until the work method statement is approved by the Manager.
Acceptance by the Manager of a proposed work method statement in no way reduces the
Contractor’s liability to achieve the requirements described in this Specification.
Appendix A contains a schedule of activities for which the Contractor shall produce work
method statements.
1.10 Survey requirements
Prior to commencing construction, the Contractor shall establish a survey grid over the Works
footprint. The survey grid shall be a maximum 10 m spacing over the Works footprint, as well as
any locations at which there is a change or break in grade and set out points identified on the
Contract Drawings. The elevation of excavated surfaces and placed materials shall be recorded
at these grid locations.
Survey data shall be provided to the Manager in graphical and tabular formats. All survey shall
be to Mine Grid and levels shall be based on Australian Height Datum (AHD).
Table 1-2 contains a schedule of survey requirements for the Works.
Table 1-2 Survey requirements
Component Survey requirements
Prepared subgrade Upon completion of the prepared subgrade, survey the elevation at all grid locations and breaks in grade.
PE geomembrane Ongoing survey during installation of the PE geomembrane, survey the location of all panels, seams, patches, destructive tests, defects and repairs.
Seepage collection drain Following installation of the seepage collection drain, survey the levels and alignments of all pipework at maximum 10 m spacing and at any changes in grade.
Anchor trenches Upon backfilling of anchor trenches, survey the alignment and level of all anchor trenches.
1.11 Witness and hold points
The following information applies to witness and hold points for the Works:
A hold point is a defined position in the Works beyond which work shall not proceed without
mandatory verification and acceptance by the Manager
A witness point is a nominated position in the Works where the option of attendance may
be exercised by the Manager, after notification of the requirement
It shall be the Contractor’s responsibility to ensure that all obligations are fulfilled in regards
to the witness and hold points within the Contract
The Contractor shall give the Manager a minimum 2 days’ notice prior to the required
inspection
Where the witness or hold point relates to the condition of a surface or installed material,
the Contractor shall verify that the completed surface has achieved full conformance with
the Contract Documents
Witness or hold points may be released for part of the Works Area only, as defined by the
Manager, so that the Works can be completed in a sequenced manner. The Manager’s
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approval of the completed items is required prior to the release of each witness or hold
point.
Table 1-3 contains a list of activities to which witness and hold points apply.
Table 1-3 Witness and hold points
Item Description Witness Hold 1 General 1.1 Provision of required pre-construction submittals, including
general work method statements, management plans and details of proposed testing firm(s)
1.2 Provision of work method statements and any associated design documentation (incl. panel layout drawings)
2 Subgrade preparation 2.1 Completion of subgrade preparation works (side slopes,
seepage collection trench and anchor trench)
2.2 Survey after completion of subgrade preparation works
3 Lining System
3.1 Completion of trial seams, approval of work method statement and detail for connection to existing geomembrane liner
3.2 Completion of installation of secondary geomembrane layer
3.3 Survey of completed primary geomembrane layer
3.4 Installation of pipework in seepage collection trench 3.5 Survey of pipework in seepage collection trench
3.6 Completion of installation of drainage 3.7 Backfilling of seepage collection trench 3.8 Survey after backfilling seepage collection trench 3.9 Completion of the installation of primary geomembrane layer 3.10 Survey of completed primary geomembrane layer
1.12 Works as Executed Drawings
The Contractor shall provide one (1) set of Works as Executed Drawings, which shall include all
corrections and as-constructed information done in a professional draftsman-like manner. All
Works as Executed Drawings shall be certified by a Registered Surveyor.
The following Works as Executed Drawings shall be prepared as a minimum:
Finished installed contours of the subgrade (determined prior to placement of the PE
geomembrane).
Finished installed alignments, levels and grades of the prepared seepage collection trench
and pipework.
Finished installed contours of the completed lining system including the anchor trench.
All Works as Executed Drawings shall include test locations, showing as a minimum the
approximate location, identification number, date sampled and type of testing completed.
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2. PE geomembrane 2.1 General
This section contains the requirements for (PE) polyethylene geomembrane.
The Manager may reject any PE geomembrane that does not meet or exceed the requirements
of this section.
Any PE geomembrane rejected by the Manager shall be removed from the site and replaced at
the expense of the Contractor.
2.2 Standards
2.2.1 American Society for Testing and Materials Standards
Relevant American Society for Testing and Material (ASTM) standards are as follows:
D792 Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics
by Displacement
D1004 Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting
D1204 Standard Test Method for Linear Dimensional Changes of Non-rigid Thermoplastic
Sheeting or Film at Elevated Temperature
D1238 Standard Test Method for Flow Rates of Thermoplastics by Extrusion Plastometer
D1505 Standard Test Method for Density of Plastics by the Density Gradient Technique
D1603 Standard Test Method for Carbon Black in Olefin Plastics
D3895 Standard Test Method for Oxidative-Induction Time of Polyolefins by Differential
Scanning Colorimetry
D4218 Standard Test Method for Determination of Carbon Black Content in Polyethylene
Compounds by the Muffle-Furnace Technique
D4354 Standard Practice for Sampling of Geosynthetics and Rolled Erosion Control
Products(RECPs) for Testing
D4437 Standard Practice for Determining the Integrity of Field Seams Used in Joining
Flexible Polymeric Sheet Geomembranes
D4439 Standard Terminology for Geosynthetics
D4833 Standard Test Method for Index Puncture Resistance of Geotextiles,
Geomembranes, and Related Products
D4873 Standard Guide for Identification, Storage, and Handling of Geosynthetic Rolls and
Samples
D5199 Standard Test Method for Measuring the Nominal Thickness of Geosynthetics
D5397 Standard Test Method for Evaluation of Stress Crack Resistance of Polyolefin
Geomembranes Using Notched Constant Tensile Load Test
D5596 Standard Test Method for Microscopic Evaluation of the Dispersion of Carbon Black
in Polyolefin Geosynthetics
D5641 Standard Practice for Geomembrane Seam Evaluation by Vacuum Chamber
D5721 Standard Practice for Air-Oven Aging of Polyolefin Geomembranes
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D5820 Standard Practice for Pressurized Air Channel Evaluation of Dual Seamed
Geomembranes
D5885 Standard Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by
High Pressure Differential Scanning Colorimetry
D5994 Standard Test Method for Measuring the Core Thickness of Textured
Geomembranes
D6370 Standard Test Method for Rubber-Compositional Analysis by Thermogravimetry
(TGA)
D6392 Standard Test Method for Determining the Integrity of Non-Reinforced
Geomembrane Seams Produced Using Thermo-Fusion Methods
D6395 Standard Practice for Non-destructive testing of Geomembrane Seams using Spark
Test
D6693 Standard Test Method for Determining Tensile Properties of Non-Reinforced
Polyethylene and Non-Reinforced Flexible Polypropylene Geomembranes
D7238 Test Method for Effect of Exposure of Unreinforced Polyolefin Geomembrane Using
Fluorescent UV Condensation Apparatus
D7240 Leak Location using Geomembranes with an Insulating Layer in Intimate Contact
with a Conductive Layer via Electrical Capacitance Technique (Conductive Geomembrane
Spark Test)
D7466 Standard Test Method for Measuring Asperity Height of Textured Geomembranes
2.2.2 Geosynthetic Research Institute Standards
Relevant Geosynthetic Research Institute (GRI) standards are as follows:
GM9 Standard Practice for Cold Weather Seaming of Geomembranes
GM10 Specification for the Stress Crack Resistance of Geomembrane Sheet
GM13 Standard Specification for Test Methods, Test Properties, and Testing Frequency for
High Density Polyethylene (HDPE) Smooth and Textured Geomembranes
GM14 Standard Guide for Selecting Variable Intervals for Taking Geomembrane
Destructive Seam Samples Using the Method of Attributes
GM17 Standard Specification for Test Methods, Test Properties, and Testing Frequency for
Linear Low Density Polyethylene (LLDPE) Smooth and Textured Geomembranes
GM19 Standard Specification for Seam Strength and Related Properties of Thermally
Bonded Polyolefin Geomembranes
GM20 Standard Guide for Selecting Variable Intervals for Taking Geomembrane
Destructive Seam Samples Using Control Charts
GM29 Standard Practice for Field Integrity Evaluation of Geomembrane Seams (and
Sheet) Using Destructive and/or Non-destructive Testing
2.3 Submittals
2.3.1 Prior to selection of the polyethylene geomembrane manufacturer
The Contractor shall submit the following to the Manager for review and approval prior to
selection of a PE geomembrane manufacturer (per manufacturer and product):
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Product manufacturer
Product name
Material data sheet showing the material properties of the proposed PE geomembrane
A list documenting no less than 40 completed facilities totalling a minimum of 200 hectares
for which the manufacturer has manufactured PE geomembrane similar to this
Specification. For each facility the following information shall be provided:
– Name and purpose of the facility
– The location and date of installation
– The name of the owner, the project manager, designer, fabricator (if any), and the
installer
– If requested, the name and telephone number of the contact at the facility who can
discuss the project
– The PE geomembrane type, thickness, and total square metres of the installation surface.
Documentation indicating that the polymer supplier has previously produced a minimum of
1,000 tonne of polymer of the same composition as that proposed for use in the
manufacture of the PE geomembrane for the Works
Manufacturer’s quality control and assurance procedures.
2.3.2 Prior to delivery of polyethylene geomembrane to site
The Contractor shall submit the following to the Manager for review and approval prior to
delivery of PE geomembrane to site (per PE geomembrane product):
Manufacturer’s certificate of compliance outlining conformance with the requirements of this
Specification
Manufacturer’s quality control and assurance test results
Certification that the PE geomembrane supplied for this work was manufactured as
consecutive rolls from a single lot or from consecutive lots. If the PE geomembrane is not
manufactured from consecutive lots, the resin manufacturer shall provide certification of
quality and consistency of the resin characteristics
Statement on the origin of the resin, its identification (type and lot number), resin supplier’s
name and production plant, resin brand name and type, and the maximum amount of
recycling polymer material added to the raw resin
Copies of quality control certificates issued by the resin supplier which shall include testing
conducted to verify conformance with Table 2-1
Certifications that the PE geomembrane and extrudate produced for the Works have the
same properties and are of the same resin
Complete description of the manufacturer’s shipping, handling and storage procedures
Manufacturer’s installation procedures and requirements
Work method statement for PE geomembrane delivery, storage, handling and installation.
This shall include seaming and jointing, welding, procedures for testing and repairing,
proposed handling equipment and restraining methods, and other information that shall
promote proper use
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2.3.3 Prior to installation of polyethylene geomembrane
The Contractor shall submit the following to the Manager for review and approval prior to installation of the PE geomembrane:
Delivery, storage and handling log for all PE geomembrane rolls to be used in the Works,
including delivery dockets, roll number and identification, delivery inspection checklist,
details of storage and handling
Proposed panel placement drawing, showing the location and reference number of all
panels and expected seams, connections and penetrations, panel dimensions and layout,
and the order of panel installation
Survey of the underlying surface in accordance with Section 1.10
Results of independent material conformance testing as provided by the CQA Engineer.
2.3.4 Following installation of polyethylene geomembrane
The Contractor shall submit the following to the Manager for review and approval following
installation of the PE geomembrane:
Panel placement log, providing details on panel number and associated roll number, date
and time placed, condition of receiving surface, weather conditions and precipitation
events, QA checks performed, and all other relevant information
Trial weld log, recording all trial welds and testing undertaken
Field welding log providing details of all field welding undertaken, including:
– Weld type
– Weld ID number
– ID numbers of panels to be joined
– Name of welder
– Details of equipment used
– Ambient air temperature
– Geomembrane surface temperature
– Weld temperature
– Any problems or issues arising during welding.
Field sampling and testing results, including non-destructive and destructive tests
Results of electrical leak location survey as provided by the CQA Engineer (refer Section2.14)
Finalised panel placement drawing showing the as-built location of all panels, seams,
connections and penetrations
Defects and repairs log, showing details of all defects identified and repairs completed.
2.4 Manufacturer’s quality control
The manufacturer shall follow a quality control program, approved by the Manager, throughout the manufacturing of all PE geomembrane for the Works.
Manufacturer’s quality control submissions shall include:
Date of manufacture
Lot number, roll number, length and width
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Manufacturer quality control documentation for the particular lot of resin used in the
production of the rolls delivered
Cross-referencing list delineating the corresponding resin used in the production of the rolls
delivered
Quality control program laboratory-certified reports
The manufacturer’s approved quality assurance stamp and the technician’s signature.
The frequency of sampling and testing shall be in accordance with Table 2-1.
The Manager may reject any PE geomembrane rolls that have not been sampled and/or tested
in accordance with this section.
All PE geomembrane rolls rejected by the Manager shall be removed from the site and replaced at the expense of the Contractor.
2.5 Manufacturer’s quality assurance
The manufacturer shall follow a quality assurance program, approved by the Manager, throughout the manufacturing of all PE geomembrane for the Works.
The frequency of sampling and testing shall be in accordance with ASTM D4354.
The Manager may reject any PE geomembrane rolls that have not been sampled and/or tested in accordance with this section.
All PE geomembrane rolls rejected by the Manager shall be removed from the site and replaced at the expense of the Contractor.
2.6 Material
The PE geomembrane shall:
Be manufactured of new, first-quality resin and shall be compounded and continuously
manufactured specifically for the Works. The resin manufacturer shall certify each batch for
the acceptance criteria listed in Table 2-1
Comply with the acceptance criteria specified in Table 2-1
Not contain more than 1 percent non-volatile pigment or fillers other than carbon black
Not be factory seamed.
The Contractor shall supply manufacturer’s quality control and assurance testing results in accordance with the testing frequencies identified in Table 2-1 showing that the proposed
material meets the requirements of this table. Samples taken shall be representative of the whole material source and shall be evenly distributed across the roll lots.
If required by the Manager, a sample of the PE geomembrane shall be provided (per product)
and the Manager and/or CQA Engineer may undertake an inspection of the manufacturer’s facility. The Contractor shall cooperate fully with the Manager and CQA Engineer to allow this inspection to occur.
PE Geomembrane shall be smooth surfaced. The primary geomembrane as shown on the Contract Drawings shall be 1.5 mm thick, ‘conductive’ geomembrane. The geomembrane shall have a coextruded, electrically conductive bottom layer such that a leak location survey may be
undertaken in accordance with the procedures outlined in ASTM D 7240.
The secondary geoemembrane as shown on the Contract Drawings shall be 1.5 mm thick ‘non-conductive’ geomembrane.
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Table 2-1 Acceptance criteria – PE geomembrane
Property Test method Acceptance criteria Minimum testing frequency
Resin (1)
Density (min) ASTM D1505 or D792 (method
B) 0.932 g/cm3
per resin lot
Melt index (maximum) (2) ASTM D1238 1.0 g/10 min per resin lot
Sheet
Thickness (min. average) ASTM D5199 1.5 mm every roll
Thickness (min.) - Lowest individual of 10 readings
ASTM D5199
1.35 mm every roll
Density (min.) ASTM D1505 or D792 (method
B) 0.94 g/cm3 90,000 kg
Tensile properties (min. average) (3) - yield strength - break strength - yield elongation - break elongation
ASTM D6693
22 N/mm 40 N/mm
12% 700%
9,000 kg
2% modulus (max.) ASTM D5323 - per each formulation
Tear resistance (min. average) ASTM D1004 187 N 20,000 kg
Puncture resistance (min. average) ASTM D4833 480 N 20,000 kg
Stress crack resistance (4) ASTM D5397 600 hours per each formulation
Dimensional stability ASTM D1204 +2% 90,000 kg
Carbon black content (range) ASTM D4218 (5) 2 to 3%
9,000 kg (HDPE) or 20,000 kg (LLDPE)
Carbon black dispersion (category) (6) ASTM D5596 Cat 1 or 2 only 20,000 kg Oxidative induction time (OIT) (min. average) (7) - standard OIT AND - high pressure OIT
ASTM D3895
ASTM D5885
100 min
400 min
90,000 kg
1 Base resin density without carbon black or additives added
2 Conducted at 190°C with 2.16 kg mass applied
3 Machine direction (MD) and cross machine direction (XMD) average values should be on the basis of five test specimens each direction:
- HDPE yield elongation is calculated using a gage length of 33 mm
- HDPE break elongation is calculated using a gage length of 50 mm
- LLDPE break elongation is calculated using a gage length of 50 mm at 50 mm/min
4 The SP-NCTL test is not appropriate for testing geomembranes with textured or irregular rough surfaces. Test should be conducted on smooth edges of textured rolls or on smooth sheets made from the same formulation as being used for the textured sheet materials. The yield stress used to calculate the applied load for the SP-NCTL test should be the manufacturer’s mean value via MQC testing
5 Other methods such as ASTM D1603 (tube furnace) or ASTM D6370 (TGA) are acceptable if an appropriate correlation to ASTM D4218 (muffle furnace) can be established
6 Carbon black dispersion (only near spherical agglomerates) for 10 different views:
- 10 in categories 1 or 2 only, none in category 3
7 Samples to be evaluated at 30 and 60 days to compare with the 90 day response
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Property Test method Acceptance criteria Minimum testing frequency
Oven aging at 85°C (min. average) - standard OIT AND - high pressure OIT
ASTM D5721
ASTM D3895
ASTM D5885
55% retained at 90 days
80% retained at 90
days
per each formulation
UV resistance (min. average) (8) - high pressure OIT (9)
ASTM D7238
ASTM D5885
50% retained after 1600 hours
per each formulation
2.7 Roll and sample identification
All PE geomembrane rolls and samples shall be identified in accordance with ASTM D4873.
Each roll or panel shall carry a label which identifies, as a minimum:
Product name, grade and name of manufacturer
Date of manufacture, batch number
Material thickness
Roll number
Roll length
Roll weight
Roll width
Handling guidelines
Reference numbers to raw material batch and laboratory certified reports
The manufacturer’s approved quality assurance stamp and the technician’s signature.
The Manager may reject any PE geomembrane rolls or samples that have not been identified in
accordance with this section.
All PE geomembrane rolls rejected by the Manager shall be removed from the site and replaced
at the expense of the Contractor.
2.8 Delivery, storage and handling
The Contractor shall prepare a work method statement for delivery, storage, handling and
installation of PE geomembrane, including repair methods (refer Appendix A). The work method
statement shall be submitted to the Manager for review and comment prior to delivery of the PE
geomembrane to site.
The delivery, storage and handling components of the work method statement shall be
developed in accordance with the guidance provided below:
Delivery, storage and handling of all PE geomembrane rolls and samples shall be
undertaken in accordance with the manufacturer’s instructions and ASTM D4873 as a
minimum
8 The condition of the test should be 20 hour UV cycle at 75oC followed by 4 hour condensation at 60oC
9 UV resistance is based on percent retained value regardless of the original high pressure OIT value
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Rolls shall be delivered to site, handled and stored in such a manner that no damage
occurs to the rolls
Roll cores shall be sufficiently strong to ensure that they do not deflect by more than half
their diameter during delivery, storage and handling
Rolls shall be stored in a location away from construction traffic but sufficiently close to the
installation area to minimise handling. The storage area shall be level, dry, well-drained and
stable, and shall protect the product from precipitation, chemicals, excessive heat, UV
radiation, standing water, vandalism and animals
PE geomembrane roll stacks shall be limited to the height at which installation personnel
can safely manoeuvre the handling equipment. The recommended maximum stack height
is three rolls
Rolls shall be handled using a spreader stinger bar. The bar shall be capable of supporting
the full weight of the rolls without significant bending. Under no circumstances shall the rolls
be dragged, lifted from one end, lifted in the middle of the roll, lifted with the forks of a
forklift or pushed to the ground from the delivery vehicle. The Contractor may nominate
alternate handling equipment and plant for approval by the Manager as part of their work
method statement
The Contractor shall inspect all PE geomembrane rolls for defects and damage upon
delivery.
The Manager may reject any PE geomembrane rolls that have not been delivered, stored or
handled in accordance with this section.
All PE geomembrane rolls rejected by the Manager shall be removed from the site and replaced
at the expense of the Contractor.
2.9 Preparation of receiving surface
Prior to placement of PE geomembrane, the receiving surface shall exhibit the following
characteristics:
The surface shall be smooth, flat, firm and unyielding to the satisfaction of the Manager
The surface shall not exhibit visible deformation, rutting, yielding and/or show signs of
distress or instability during final proof rolling (if required)
The surface shall be free of debris, roots, angular material (such as sharp rocks),
desiccation cracks, abrupt breaks, indentations, sudden changes in grade, defects and/or
imperfections that may result in damage to the overlying materials
No loose, coarse-grained material shall remain on the surface. If required, the surface shall
be raked or graded to remove any material penetrating out of the surface greater than 10
mm
The surface shall promote drainage and excessive water shall not be allowed to pond on
the surface
The surface shall not be pebbly, tracked, rutted or otherwise disturbed by the equipment
deploying overlying materials or other traffic. Pockets, holes, or discontinuities shall be
repaired
All construction stakes, hubs, or other items used for grade control shall be removed and
any voids filled. Any unsuitable material shall be over-excavated to a depth of 100 mm and
replaced with approved material
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The surface shall be maintained at sufficient moisture content to prevent desiccation during
the Works.
The receiving surface shall be surveyed as per the requirements of Section 1.10.
Placement of PE geomembrane shall not proceed until the receiving surface has been
inspected and approved by the Manager.
2.10 Installation
2.10.1 General
The Contractor shall prepare a work method statement for delivery, storage, handling and
installation of PE geomembrane (refer Appendix A). The work method statement shall be
submitted to the Manager for review and comment prior to delivery of the PE geomembrane to
site.
The installation component of the work method statement shall be developed in accordance
with the guidance provided below.
The Manager may reject any PE geomembrane rolls that have not been installed in accordance
with this section.
All PE geomembrane rolls rejected by the Manager shall be removed from the site and replaced
at the expense of the Contractor.
2.10.2 Weather conditions
The Contractor shall consider the weather conditions on a daily basis to confirm they are
suitable for placement of PE geomembrane.
PE geomembrane shall not be placed or seamed:
If moisture prevents proper subgrade preparation, panel placement and/or panel seaming
During precipitation, during hail, during periods of excessive fog, during periods of
excessive dust, in standing water, on excessively wet surfaces, in the presence of excess
moisture (such as dew and/or ponded water)
During periods of excessive winds (>30 kph) or when gusting wind conditions interfere with
handling operations
When sheet temperatures are lower than 0° or higher than 65° as measured by a calibrated
infrared thermometer or surface thermocouple.
2.10.3 Traffic
Equipment used shall not damage the PE geomembrane by handling, trafficking, leakage of
hydrocarbons, or by other means.
No vehicle shall be allowed to travel directly on the PE geomembrane unless approved by the
Manager. Prior to approval, the Contractor shall provide the Manager the following information:
Guidance from the manufacturer on suitable plant for trafficking for the proposed PE
geomembrane and confirmation that the Contractor shall only use this plant
Guidance from the manufacturer on suitable trafficking method for the proposed PE
geomembrane and confirmation that the Contractor shall only use this trafficking method
Certification from the manufacturer that the above trafficking method and plant shall not
void the warranty for the proposed PE geomembrane.
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 17
2.10.4 Placement
PE geomembrane shall be placed in accordance with the following:
The PE geomembrane shall be placed and seamed in accordance with this Specification,
the Contract Drawings, the approved work method statement and the manufacturer's
instructions. Any contradictions shall be clarified with the Manager
Prior to placement, each roll shall be inspected by the Contractor for damage and/or
defects, including tears, abrasion, indentation, cracks, thin spots or any other faults or
defects. If damage or defects are identified, the roll shall be inspected by the Manager and
approved or rejected
PE geomembrane shall be protected from damage due to exposure to sunlight, dirt, dust
and other hazards
PE geomembrane shall be placed such that the panels are anchored at the crest of the
slope and form a continuous layer down the side walls and slopes and across the base
The arrangement of the PE geomembrane panels shall be in accordance with the approved
panel placement drawing and any changes approved by the Manager
Installation shall progress from the highest elevations to the lowest
PE geomembrane rolls shall be placed in an orderly fashion which shall minimise or
prevent surface water from flowing below previously installed PE geomembrane
PE geomembrane shall not be allowed to ‘bridge over’ voids or low areas. The PE
geomembrane shall be placed to allow intimate contact with the subgrade or underlying
geosynthetic
PE geomembrane shall be installed without undergoing excessive buckling, wrinkling or
tensioning
PE geomembrane shall not be dragged across an unprepared surface. If the PE
geomembrane is dragged across an unprepared surface, it shall be inspected for defects
and repaired or rejected if necessary
Where there is a geosynthetic layer below, the installation of the PE geomembrane shall be
undertaken in a manner so as not to damage the underlying layer
Sandbags or equivalent ballast shall be used as necessary to temporarily hold the PE
geomembrane in position and prevent uplift by wind. In case of high winds, continuous
loading shall be placed along edges of panels to minimise wind flow under the panels.
Sandbag material shall be sufficiently close-knit to prevent soil fines from working through
the bags and discharging on the PE geomembrane
Only those PE geomembrane rolls which can be seamed or permanently anchored on at
least two sides on the same day shall be placed on a daily basis. All other sides shall be
temporarily anchored
PE geomembrane installed on slopes shall be fixed in anchor trenches as shown on the
Contract Drawings and Section 2.10.5. PE geomembrane panels shall be anchored as
soon as possible. The Geosynthetic Installer shall program anchor trenches backfilling
when the temperature is coolest to minimise effects of material expansion
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 18
Personnel working on the PE geomembrane shall not smoke, wear damaging shoes,
excessively traffic or engage in other activities which may damage the PE geomembrane.
PE geomembrane in heavy traffic areas shall be protected by a geosynthetic overlay
PE geomembrane shall be cut from each roll with an approved hook blade knife with flat
zones on each end
PE geomembrane rolls shall be freely suspended during placement
The method used to unroll the PE geomembrane shall not cause bridging, excessive
wrinkles, scores, scratches and/or crimps
Folds and wrinkles caused by PE geomembrane panel placement or thermal expansion
shall be minimised
After placement, the PE geomembrane shall be free of excessive buckles, wrinkles, ripples,
creases, folds and irregular stressing before the overlying cover material or geosynthetic is
placed.
2.10.5 Anchoring of geosynthetics
Anchor trench excavation, backfill, and compaction shall be completed to the line and grades
shown on the Contract Drawings. A work method statement shall be prepared for the excavation
and backfill of anchor trenches during the Works with consideration to the guidance below.
Anchor trenches shall be prepared with slightly rounded corners where the geosynthetics enter
the trench so as to avoid sharp bends in the geosynthetic material. The base of the anchor
trench must be a smooth uniform surface that is free of defects and loose material.
The geosynthetic layers shall be placed in the trench as per the Contract Drawings to ensure
effective anchorage. Fill material shall be placed in maximum 100 mm loose lifts if compacted
with hand-operated compaction equipment, or maximum 200 mm loose lifts if compacted with a
self-propelled compactor.
The Contractor shall repair or replace any geosynthetics damaged as a result of placement or
compaction of backfill.
2.10.6 Seaming
PE geomembrane shall be seamed in accordance with the following guidance.
General
The PE geomembrane shall be field seamed into a continuous sheet across the Works by
using either dual hot wedge fusion welding or extrusion welding seams
Dual hot wedge fusion welding shall be the preferred method of welding and shall be used
for primary welds between adjacent PE geomembrane panels. Extrusion welding shall only
be used for detailed work, repair work, or in areas inaccessible for dual hot wedge fusion
welding (where approved by the Manager)
PE geomembrane placement shall be limited to that which can be seamed in one day
Trial seams shall be completed each day as per Section 2.11
All seams shall be ‘shingled’ down-slope to promote runoff (roof tile fashion)
All field seaming operations shall be supervised by the Seaming Foreman and no field
seams shall be made without the Seaming Foreman present
Prior to welding, the prepared weld surfaces shall be free of dust, dirt, debris, markings,
foreign material and any other potential contaminants that would inhibit welding. Where
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 19
contamination does occur, the prepared surfaces shall be thoroughly cleaned and the weld
completed
There shall be no free moisture in the weld area during welding. If free moisture is located
in the weld area, mitigation measures during seaming shall be employed as approved by
the Manager
The Geosynthetic Installer shall have an independently calibrated handheld temperature
measuring device to confirm the temperatures of each and every welding machine prior to
the commencement of any test or field welds. All information regarding the results gained
from the temperature device shall be recorded for each welding machine
Any electric generators used in welding shall be placed on a smooth base such that no
damage occurs to the underlying PE geomembrane
Adjacent to anchor trenches, seaming shall extend up the panels a minimum of 300 mm
past the crest of the anchor trench.
Weld locations
PE geomembrane panel placement shall take into consideration the site geometry including:
Field seams shall be orientated parallel to the line of maximum slope
For batters with a 10% grade or steeper, transverse (cross-slope) seams shall not be
permitted
No cross seams shall be allowed within 1,500 mm of the toe of any slope
In corners and odd shaped geometric locations, the number and total length of field seams
shall be minimised
Seams shall not be located at low points
All cross seams shall be offset at least 600 mm from the cross seam of the adjacent panel
and be extrusion or wedge welded where they intersect
All primary welds used to connect panel ends to sheets shall form T-joins (tees). These T-
connections shall have a distance of at least 500 mm. The welding seams of the PE
geomembrane cannot cross (no cruciform connections).
Dual hot wedge fusion welding
The dual hot wedge fusion welding shall be conducted using the split head wedge fusion
weld method, fusing the upper and lower overlapped PE geomembrane panels
The welding equipment shall be capable of continuously monitoring and controlling the
temperature in the zone of contact where the machine is actually fusing the PE
geomembrane so as to ensure that changes to environmental conditions shall not
adversely affect the integrity of the weld
Seams shall have a finished overlap of a minimum of 150 mm for dual hot wedge fusion
welding but in any event, sufficient overlap shall be provided to allow peel tests to be
performed on the seam
The dual hot wedge fusion welding shall form two contact fusion areas of a minimum width
of 15 mm and a 5 mm minimum wide void between each of the separate parallel weld
zones.
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Extrusion welding
The extruder may be a combination sheet pre-heat and extruder type or a combination
dynamic mixing assembly and extruder type
The extrudate shall be manufactured from the same resin type used in the manufacture of
the relevant PE geomembrane being welded. All physical properties shall be identical to
those possessed by the raw PE geomembrane material. The Geosynthetic Installer shall
provide certification from the manufacturer that the relevant PE geomembrane and
extrudate produced for the Works have the same properties and are of the same resin for
each batch
During welding, the Geosynthetic Installer shall be responsible for regularly checking,
calibrating and recording of:
o Preheat air flow and temperature at the nozzle
o Extrudate flow and temperature at the barrel outlet
Seams shall have a finished overlap of a minimum of 75 mm for extrusion welding but in
any event, sufficient overlap shall be provided to allow peel tests to be performed on the
seam
The minimum width of the surface extruded bead shall be 30 mm
Prior to welding, oxidation by-products shall be removed from the weld area by grinding or
buffing. Grind marks shall not be deeper than 10% of the PE geomembrane thickness.
Seam grinding shall be been completed less than one hour before seam welding. The end
of welds more than five minutes old shall be ground to expose new material before
restarting a weld
Prior to welding, the extruder shall be purged until all the heat-degraded extrudate is
removed
Welding shall be undertaken in one direction only
A smooth insulating plate or fabric shall be placed beneath the hot welding apparatus after
use.
Pipe boots
Pipe boots may be constructed in the factory or in the field in accordance with the detail
shown on the Contract Drawings from relevant PE geomembrane conforming to this
Specification.
2.11 Weld trial
The Contractor shall trial the proposed connection detail of the existing PE Geomembrane to
the new PE Geomembrane as shown on the Contract Drawings. The weld trial shall be
undertaken at a minimum of two locations (one in each pond cell) as nominated by the
Manager.
The weld trial shall be verified in accordance with the general requirements outlined in Section
2.12 and Section 2.13 of this Specification. A minimum of three test locations shall be sampled
at each trial location.
Approval of the weld trial shall be on the basis of demonstrated conformance testing as required
by this Specification. If the requirements of this Specification and associated conformance
testing are not met, the Contractor shall repeat the weld trials in locations nominated by the
Manger, using an alternative methodology and/or weld detail if required. The weld trial shall be
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 21
re-tested and repeated until the requirements of this Specification are met. The weld trial shall
constitute a Hold Point.
2.12 Trial seams
The trial seams should be performed on the existing PE geomembrane prior to undertaking the
trial seams connecting the new and existing PE geomembrane. The effectiveness of the trial
seams shall be compared to the results of trials on the existing PE geomembrane to assess the
effectiveness of the weld trial.
Trial seams shall be performed on fragment pieces of PE geomembrane to verify that seaming
conditions are satisfactory and to supply test specimens for the CQA program.
Trial seams shall be conducted at the beginning of each seaming period and at least once each
four hours for each seaming apparatus used that day. Trial seams shall be repeated if any
welding stoppage exceeds one hour and if weather conditions change. Trial seams shall be
made under the identical conditions as the actual seams.
Each seamer shall make at least one trial seam each day for each seam method for each
seaming equipment apparatus to be used that day.
Trial seams shall be a minimum of 1,350 mm by 300 mm with seam centred.
The trial seam sample shall be cut into three subsamples (450 mm by 300 mm with seam
centred).
The two subsamples from each end shall immediately be tested onsite for peel and shear
strength in accordance with GM19.
If either specimen does not meet the acceptance criteria, the seamer and seaming apparatus
and/or methods shall not be accepted and shall not be used for seaming until the deficiencies
are corrected and two consecutive trial seams are successful.
The central portion of the trial seam sample shall be labelled and provided to the CQA Engineer
for destructive testing at the CQA Engineer’s Independent Testing Firm. A minimum one trial
seam sample per day shall be subjected to destructive testing. The Manager may reduce the
frequency of trial seam destructive testing at the CQA Engineer’s Independent Testing Firm, in
consultation with the CQA Engineer, if the field tensiometer appears adequate for assuring trial
seam quality.
If a trial seam sample records a non-conforming result for a test conducted at the CQA
Engineer’s Independent Testing Firm, a destructive test seam sample shall be taken by the
Contractor from the seams completed by the seamer during the shift related to the considered
trial seam. These samples shall be forwarded to the CQA Engineer’s Independent Testing Firm
by the Contractor and if they recording non-conforming test results, the length of seam
represented by the test sample shall be rejected.
The conditions of this section are considered as met for a given seam if a destructive seam test
sample has already been taken from the considered seam(s).
2.13 Field seam sampling and testing
2.13.1 General
Testing parameters, requirements and anticipated schedules shall be continuously reviewed by
the Contractor to ensure that adequate personnel and proper equipment shall be available.
Field seam sampling and testing shall be performed after seaming to verify that the mechanical
characteristics of the seams do not compromise the PE geomembrane integrity.
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 22
Test results shall be provided to the Manager in accordance with Section 1.7.
2.13.2 Destructive seam testing
Destructive seam samples shall be taken and tested in accordance with Table 2-2.
Repair patches shall be extrusion welded over the areas where destructive seam samples have
been taken and shall be subjected to non-destructive testing.
The location of each destructive seam sample shall be up to the discretion of the Manager and
CQA Engineer and designated on a copy of the panel placement drawing, along with the date
and time of sampling and the sample number.
Destructive test samples shall be a minimum of 1350 mm by 300 mm with seam centred.
The destructive seam sample shall be cut into 3 subsamples (450 mm by 300 mm with seam
centred).
The two subsamples from each end shall be taken and tested on-site for peel and shear
strength.
If both on-site subsamples meet the acceptance criteria of Table 2-2, the central portion of the
test sample shall be labelled and provided to the CQA Engineer for destructive testing at the
CQA Engineer’s Independent Testing Firm.
If either on-site or off-site test results do not meet the acceptance criteria listed in Table 2-2, the
length of seam represented by the test sample shall be rejected.
Table 2-2 Destructive seam testing requirements
Test description Test method Minimum test frequency (10)
Acceptance criteria (11)
Peel strength (12) ASTM D6392 1 test per 150 m (13) (or part thereof)
As per GM19
Shear strength ASTM D6392 1 test per 150 m (14) (or part thereof)
As per GM19
2.13.3 Non-destructive seam testing
All seams shall be non-destructively tested over the entire length of seam by at least one of the
methods in Table 2-3. The tests shall be undertaken no earlier than one hour after welding. In
addition to the above tests, the welds shall be visually inspected to assess the quality of the
workmanship and the appearance of the welded seam.
Table 2-3 Non-destructive seam testing requirements
Test description Test method Minimum test frequency
Acceptance criteria
Vacuum box ASTM D5641 No imperfections
10 A minimum of one series of destructive tests shall be performed each day that seaming is performed
11 All destructive test results shall be based on Film-Tear Bond (FTB) criteria. All samples which produce seam failures shall be considered unacceptable
12 Peel strength testing shall be performed on both Weld A and Weld B
13 When ambient air temperatures during seaming operations are less than 10oC, testing frequency shall be increased to one test per 75 linear meters
14 When ambient air temperatures during seaming operations are less than 10oC, testing frequency shall be increased to one test per 75 linear meters
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 23
Test description Test method Minimum test frequency
Acceptance criteria
Air pressure (15) ASTM D5820 All seams shall be tested by at least one of these three test methods as appropriate
Refer Table 2-4
Spark test ASTM D6365 No spark
Table 2-4 Air pressure test schedule
Geomembrane thickness
Minimum pressure Maximum pressure Maximum pressure differential (16)
1.5 mm 190 kPa 250 kPa 20 kPa
2.13.4 Pipe boot seam testing
All pipe boot seams shall be spark tested with acceptable pipe boots showing no spark.
Alternative testing methods may be allowed at the discretion of the Manager.
2.13.5 Non-conforming test results
If any test specimen does not meet the acceptance criteria listed, the test series shall be
considered unacceptable and all material or length of seam represented by the test series shall
be rejected. The Geosynthetic Installer may, at no additional compensation, take additional
samples for quality control testing in an attempt to minimise the amount of material represented
by the non-conforming test result.
In the event of discrepancies between the CQA Engineer’s test results and the Contractor’s test
results, the Contractor shall be responsible for arranging a third independent testing firm to
verify test results.
An acceptable length of seam shall be defined as a length of seam which lies between
conforming destructive test locations and has passed non-destructive seam testing.
2.13.6 Field testing summary
The Geosynthetic Installer shall prepare a field testing summary for all installed PE
geomembrane. For each PE geomembrane layer, a separate copy of the panel placement
drawing shall be utilised for this summary and shall indicate the PE geomembrane layer
represented. On each sheet, the following information shall be recorded:
The location, date, sample number and test result (conforming/non-conforming) of each
destructive test series
The location, identification number and date of each non-destructive air pressure seam test
including the length of the tested seam and the result of the test (conforming/non-
conforming)
The location, date and lengths of non-destructive vacuum box testing performed on a daily
basis and the result of the tests (conforming/non-conforming)
The location, identification number and date of each non-destructive spark test including
the length of the tested seam and the result of the test (conforming/non-conforming).
15 All hypodermic needle punctures shall be repaired as per the requirements of this Specification
16 Observe and record the pressure 5 min after the initial reading. If the loss of pressure exceeds that shown, or if the pressure does not stabilize, the faulty area should be located and repaired
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 24
2.14 Electrical leak location survey
2.14.1 General
Following the installation of each PE geomembrane layer, the Leak Location Contractor
engaged by the Manager shall conduct an electrical leak location survey to detect leaks in the
PE geomembrane.
2.14.2 Preparation and support
The Contractor shall responsible for preparing the survey area for the leak location survey.
The Contractor shall be responsible for completing installation work around the edge of each PE
geomembrane layer that provides electrical isolation of the PE geomembrane for the electrical
leak location surveys. The Manager may provide further details on this procedure if requested.
The Contractor shall ensure the PE geomembrane surface is clean and dry prior to the survey.
2.14.3 Repairs
The Geosynthetic Installer shall be responsible for repairing any leaks found. Repairs shall be
undertaken in accordance with Section 2.15.
After the leak is repaired, the Leak Location Contractor shall retest the area to ensure the leak
was repaired and that there are no other leaks in the vicinity of the repair.
2.15 Defects and repairs
The Contractor and shall be responsible for inspecting the placed PE geomembrane to identify
any damage or faults in the material. The Manager and/or CQA Engineer may also undertake
inspections of the placed PE geomembrane to identify any damage or faults in the material. Any
areas of PE geomembrane damaged during installation shall be repaired by the Contractor. All
repairs shall be verified by the Manager.
The Contractor shall prepare a work method statement for delivery, storage, handling and
installation of PE geomembrane (refer Appendix A). The work method statement shall be
submitted to the Manager for review and comment prior to delivery of the geomembrane to site.
The installation component of the work method statement shall include work methods for
defects and repairs, developed in accordance with the guidance provided below:
All repairs shall be undertaken in accordance shall be undertaken in accordance with this
Specification, the approved work method statement and the manufacturer's instructions.
Any contradictions shall be clarified with the Client’s Representative. All repairs shall be
verified by the Client’s Representative
Patches and cap strips shall have rounded edges (minimum radius of 75 mm), shall be
made of the same geomembrane and shall extend a minimum of 150 mm beyond the edge
of defects. All patches shall be of the same compound and thickness as the PE
geomembrane being patched over. Patches shall be seamed using extrusion (fusion)
welding
Punctures, pin holes, blisters, small tears and localised imperfections shall be repaired
using a patch
Large tears and lengths of seam shall be repaired using a cap strip. No reseaming over
existing seams shall be permitted
Tears which lie on slopes greater than 5% or which lie in areas of stress and have sharp
ends shall have all sharp ends rounded prior to repair
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 25
The PE geomembrane below large patches and cap strips shall be cut as necessary to
prevent moisture or gas collection between sheets
Excessive wrinkles which exist at the end of seaming operations and which may become
creased during backfilling shall be cut and reseamed. Excessive wrinkles shall be defined
as a wrinkle which at the time of covering and in the opinion of the Manager, meets any of
the following criteria:
– Is nominally >200 mm in height
– May fold during backfilling
– May adversely impede the flow along the surface of the geomembrane
‘Fishmouths’ or wrinkles at the seam overlaps shall be cut along the ridge of the wrinkle in
order to achieve a flat overlap. The cut ‘fishmouths’ or wrinkles shall be seamed and any
portion where the overlap is inadequate shall then be patched with an oval or round patch
of the same geomembrane extending a minimum of 150 mm beyond the cut in all
directions. All corners of the patch shall be rounded with a 25 mm minimum radius
All repair seams shall be made in accordance with the requirements of Section 2.10.6
Each repair shall be required to pass non-destructive tests (refer Section 2.13.3). Large cap
strips may require destructive testing (refer Section 2.13.2), as directed by the Manager.
The Contractor shall submit to the Manager for review a log containing details of any defects
identified and repairs carried out.
2.16 Acceptance
The Contractor shall retain all ownership and responsibility for all PE geomembrane until final
acceptance of all work under this Contract by the Owner.
PE geomembrane shall be accepted by the Owner when all of the following conditions are met:
Required submittals are provided by the Contractor to the Manager and approved
Adequacy of all field seams, penetrations and repairs is verified by the Manager
The electrical leak location survey has been completed and all required repairs have been
completed by the Contractor
Details of all defects identified and repairs performed have been provided by the Contractor
to the Manager and approved
The CQA Engineer has provided the Manager with a recommendation that the conditions of
final acceptance have been met
The Manager has inspected and approved the finished surface/s.
GHD | Report for The Client Geosynthetic and Lining Specification[Title] 26
Appendices
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 27
Appendix A – Schedule of work method statements
Work Method Statements (non-exhaustive list)
Connection to existing liner
Construction of seepage collection trench
Excavation and backfill of anchor trenches
Geotextile installation and testing
Polyethylene geomembrane installation and testing
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 28
Appendix B – Example submittal forms
Pre-selection submittal form – geosynthetics
Submission data
Project name and location:
Submittal number:
Material designation (as per the Specification):
Reference section of Specification:
Product manufacturer:
Product name:
Proposed placement location:
Estimated quantity:
Material sample provided: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 29
Attachments
Material data sheet:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Manufacturer’s quality control and assurance
procedures:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
Submitted by:
(include title and signature)
Date:
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 30
Delivery submittal form – geosynthetics
Submission data
Project name and location:
Submittal number:
Material designation (as per the Specification):
Reference section of Specification:
Product manufacturer:
Product name:
Proposed placement location:
Estimated quantity:
Material sample provided: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 31
Attachments
Manufacturer’s certificate of compliance:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Manufacturer’s quality control and assurance
test results/reports:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Manufacturer’s shipping, handling and
storage procedures:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Manufacturer’s installation procedures and
requirements:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Work method statement for material delivery,
storage, handling and installation:
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
Submitted by:
(include title and signature)
Date:
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 32
Installation submittal form – geosynthetics
Submission data
Project name and location:
Submittal number:
Material designation (as per the Specification):
Reference section of Specification:
Product manufacturer:
Product name:
Proposed placement location:
Estimated quantity:
Material sample provided: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Material inspected by CQA Engineer: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
GHD | Report for The Client, TSF xxx, Geosynthetic and Lining Specification 33
Attachments
Delivery, storage and handling log (including
roll numbers):
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Proposed panel placement drawing: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Survey of underlying surface: □ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Independent conformance test results/reports
(provided by CQA Engineer)
□ Yes
□ No (provide reason below)
□ N/A (provide reason below)
Additional comments (including other information provided as required):
Submitted by:
(include title and signature)
Date:
GHD | Report for Hastings Technology Metals Limited - Yangibana TSF Design Development, 3219134 | 89
Appendix I – Ammonia Gas Modelling Reports
15 April 2019
To Darren Tull (Hastings Rare Earth Minerals)
Copy to Ben Hanslow
From Matthew Brannock Tel +61 7 3316 3907
Subject Yangibana TSF Ammonia Evolution Modelling Job no. 321913401
1 Appreciation of Issue
It is understood that “Hastings Technology Metals Ltd”, henceforth named “Hastings”, is enquiring about the magnitude of ammonia gas evolving from a Yangibana Tailings Storage Facility (TSF). The Hydromet TSF, under a worst case scenario, receives a stream at 76 t/h containing approximately 0.04 g/L of ammonium bicarbonate and 6.28 g/L of ammonium hydroxide solution. The quantity of ammonia evolution from the Hydromet TSF will be compared to that released from the plant into the TSF. This information will help to inform Hastings of potential health and safety risks to workers resulting from ammonia evolution, as well as the potential environmental implications as a result of the release of ammonia.
2 Methodology
To model the ammonia off-gas evolution from the Hydromet TSF, the software packages OLI Stream Analyzer and AqMB Designer were utilised. Both employ speciation chemistry modelling for the equilibrium analysis of complex aqueous systems, such as a multi-component TSF. AqMB Designer is more process design oriented (e.g. sizing of gas stripping equipment and other industrial water treatment units) whilst OLI Stream Analyzer is more chemistry oriented (i.e. it has a very sophisticated equation of state model however it cannot design or size process equipment). The preliminary AqMB results (i.e. modelling / sizing of a gas stripper – not reported here) corroborated with OLI Stream Analyzer results (i.e. a simplified representation of a TSF). The results presented cover the OLI Stream Analyzer modelling of the TSF system.
The composition data supplied by Hastings (representing a worst case scenario) is as follows.
Component Concentration (g/L)
H2O (l) 975.03
CaSO4 (aq) 1.98
K2SO4 (aq) 0.22
MgCl2 (aq) 0.23
MnSO4 (aq) 1.06
Na2SiO3 (aq) 0.03
Na2SO4 (aq) 8.39
NaCl (aq) 0.41
NH4HCO3 (aq) 0.04
C17H35CO2Na (o) 1.38
Mg 0.06
NH4OH (aq) 6.28
As the OLI Studio database did not include the surfactant, “C17H35CO2Na (o)”, the inter-species interaction of the component was modelled via NaC2H5O2 and C17H36. The former simulated the carboxy-sodium functional group, and the latter simulated the surfactant carbon chain.
In addition, elemental Mg was combined with MgCl2 to simulate a more likely oxidation state in the pond. The resulting addenda to the above information is as follows.
Component Concentration (g/L)
NaC2H5O2 0.37
C17H36 1.08
MgCl2 0.47
In order to model an approximate range of evolution conditions for ammonia off-gas, the temperature of the TSF was assumed to range from a low of 25°C to a high of 35°C (a typical range for TSFs at similar locations around Australia). The impacts of ‘fresh’ tailings entering the pond at ~52°C was ignored, as the system was assumed to be at equilibrium with the ambient air. Evaporation and rainfall has also been ignored (although it is expected that net evaporation will be positive).
Accordingly, the composition of air at both 25°C and 35°C was determined at 100% relative humidity and 1 atm of pressure. Within OLI Studio, the TSF and the surrounding air are modelled as separate streams that are then “mixed”. In order to model the impact of different ammonia partial pressures in the atmosphere surrounding the Hydromet TSF, the air “stream” was set to 10 and 20 times the volume of the incoming tailings respectively. This
also captures some of the variability in ammonia evolution resulting from different atmospheric conditions, such as increased mixing with air due to wind.
The table below summarises all investigated scenarios under varying conditions.
Air:Liquid Ratio
Solids Formation?
pH Mix Temp (°C)
10 Yes 7.0 25
10 Yes 7.0 35
10 Yes 13.0 25
10 No 10.3 25
10 Yes 10.3 25
10 Yes 9.99 35
20 Yes 7.0 25
20 Yes 7.0 35
20 Yes 13.0 25
20 No 10.3 25
20 Yes 10.3 25
20 Yes 9.99 35
These scenarios cover the impacts of:
Rough variation of partial pressure of ammonia in the atmosphere above the TSF (following ammonia off-gassing) via modification of the air to liquid ratio;
Solids precipitation and interspecies interactions within solution; pH of the TSF on ammonia off-gas evolution; Variation in ambient air temperature.
With regards to solids formation, it was assumed that the precipitation of minerals such as dolomite, quartz, and chrysotile will not occur due to the timescales required for formation. As OLI Stream Analyzer assumes an equilibrium state and is not a dynamic model, minerals such as these were excluded from the model if they were predicted.
Note that reaction kinetics were ignored as this will not affect the magnitude of the ammonia off-gassing rate while the Hydromet TSF consistently receives inflow.
3 Results
The results of the scenarios discussed above are as follows based on a ~76 t/h pond inflow worst case composition:
Pre-TSF Storage Scenarios Resulting Mass of TSF Feed N(-3)* Lost to Atmosphere
Air:Liquid Ratio
Solids Formation? pH Mix Temp (°C) (% Mass of TSF Feed)
(kg/day as NH3)
10 Yes 7.0 25 0.6 % 33
10 Yes 7.0 35 1.0 % 56
10 Yes 13.0 25 88 % 5,000
10 No 10.3 25 68 % 3,855
10 Yes 10.3 25 70 % 4,018
10 Yes 9.99 35 74 % 4,203
20 Yes 7.0 25 0.7 % 39
20 Yes 7.0 35 1.2 % 67
20 Yes 13.0 25 93 % 5,297
20 No 10.3 25 73 % 4,167
20 Yes 10.3 25 77 % 4,424
20 Yes 9.99 35 79 % 4,503
*Note that this value is the total of ammonia and ammonium, N2 from air is not included.
It is evident that at elevated pHs the predominant form of ammonia/ammonium (i.e. N(-3) oxidation state of nitrogen) is dissolved ammonia gas (rather than the ammonium ion) which has a propensity to off-gas due to low concentrations of ammonia in the atmosphere. Generally, over 98 % by mass of ammonia evolves as off-gas with the small remainder dissolved in the tailings pond. Therefore to reduce ammonia evolution, conditions within the TSF must favour ammonium formation.
It is also evident that higher temperatures result in greater off-gas production. As the ‘fresh’ tailings are at ~52 °C there is the potential for greater additional ammonia evolution than these results suggest.
When the tailings are neutralised, ~1% of the combined ammonia/ammonium sent to the Hydromet TSF by mass, escapes as ammonia off-gas. However, this would require approximately 16.4 t/d of sulphuric acid based on an influent pH of ~10, an inflow of ~78 m3/h (at 76 t/h), and an influent composition as described previously. There would also need to be a consideration of the increased potential for algal blooms as a result of the neutral pH in the pond, if a carbon and phosphorous source inadvertently enters the TSF via run-off or leaf litter.
At a pH of ~10 and 13, the combined ammonia/ammonium that escapes as ammonia off-gas rises to greater than 67 and 87 %, by mass, respectively. It is evident that a higher pH results in greater ammonia evolution. For the Hydromet TSF, a pH of 13 would result in
approximately 3,900-5,300 kg/day of ammonia being released as off-gas, based off a ~76 t/h of inflow to the pond.
The impact of this ammonia gas release on the environment and health and safety of nearby workers is unknown; would require further modelling of air quality and risk.
4 Literature Review
The evolution of ammonia off-gas from TSFs at an elevated pH is supported by literature. For wastewater containing high levels of ammonia, the adjustment of the stream to a high pH (greater than 10.5) is recommended as a means for ammonia removal. A gas stripping tower is often used for removal, as are ponds (more infrequently) where wind/waves aid removal by increasing contact at the gas-liquid interface (Boyd & Tucker, 1998; Jermakka, et al., 2015).
This can be explained by the equilibrium reaction of ammonia and water, as follows:
H2O + NH3 ⇌ OH− + NH4+
It is evident that a higher concentration of hydroxide ions will shift the equilibrium towards ammonia formation, rather than ammonium. As ammonia gas readily evolves from water if unable to disassociate, a higher pH will result in greater quantities of off-gas than otherwise.
Figure 1 provides an illustration of this relationship under ideal conditions (i.e. for a simple ammonia/ammonium mixture).
Figure 1: Ammonia/Ammonium Concentration vs pH (Richard, 1996).
5 Conclusion
Speciation chemistry modelling demonstrated that ammonia off-gas evolution increases with an increase in pH. As the Hydromet TSF is likely to have a pH of 10 or greater, it can be expected that greater than two thirds of the ammonia/ammonium incoming to the pond will escape to the atmosphere as ammonia off-gas in the range of 3,900-5,300 kg/day (based on the worst case scenario).
The implications of this from an environmental, health and safety standpoint require further air quality modelling to quantify potential risks.
Kind Regards,
Matthew Brannock Technical Director – Water and Brine
References Boyd, C. E., & Tucker, C. S. (1998). Pond Aquaculture Water Quality Management. New York: Springer
Science + Business Media. Jermakka, J., Wendling, L., Sohlberg, E., Heinonen, H., Merta, E., Laine-Ylijoki, J., . . . Mroueh, U.-M.
(2015). Nitrogen compounds at mines and quarries: Sources, behaviour and removal from mine and quarry waters-Literature study. Tekniikantie: VTT Technical Research Centre of Finland Ltd.
Richard, T. (1996). Ammonia Odors. Ithaca: Cornell University: Waste Management Institute. Retrieved from http://compost.css.cornell.edu/odors/ammonia.html
ERM Level 18 140 St Georges Tce Perth WA 6000 PO Box 7338 Cloisters Square WA 6850
Telephone: +61 8 6467 1600 Fax: +61 8 9321 5262
www.erm.com
Page 1 of 19
Registered office Environmental Resources Management Australia Pty Ltd Level 15, 309 Kent Street Sydney NSW 2000 Australia
ABN: 12 002 773 248 ACN: 002 773 248
Offices worldwide
A member of the ERM Group
Lara Jefferson Environmental Manager Hastings Technology Metals Limited Level 8 Westralia Plaza 17 St Georges Terrace Perth WA 6000
6 May 2019
Reference: 0504573
Dear Lara Jefferson
Subject: Screening level Air Quality assessment of Ammonia emissions from the Hydromet TSF.
Hastings Technology Metals Ltd engaged ERM to undertake a screening level air quality modelling assessment of ammonia emissions from its Tailings Storage Facility (TSF) at the Yangibana Rare Earths Project operations. The modelling exercise is built on the previous work undertaken by ERM (Pacific Environment, 2017 and ERM, 2018).
The model assesses the emission rate for ammonia under a worst-case scenario, presenting a level of conservatism in the modelled results. Ground level concentrations were evaluated at a number of onsite receptor locations (42 onsite receptors considering plant locations, the creek and internal roads around the Hydromet TSF) and three offsite sensitive receptors considering the accommodation camp and two homesteads. Concentrations were predicted for 1-hour, 8-hour, 24-hour, 3-minute and 15-minute averages and compared against relevant ambient and occupational health and safety (OHS) air quality criteria. The following observations were made:
No exceedances of air quality criteria were predicted at the identified offsite sensitivereceptors.
One exceedance (25.75 mg/m3) of the 15-min OHS criteria was predicted at an onsitereceptor (TSF receptor 1) located within 250 m from the centre of the source (Figure 4-1)This exceedance occurred under worst-case conditions. The next worst case scenariopredicted a concentration of 12.89 mg/m3 at this same receptor. This concentration is wellwithin the criteria (50% of the criteria).
In summary, the modelling results indicate that the maximum concentration is of low likelihood to occur and dependent on concurrence of worst case emission rate and worst case dispersion conditions (i.e., prevalence of calm conditions, transition from stable to unstable meteorological conditions, and winds blowing towards this receptor).
Yours sincerely, pp.
Lavanya Gowrisanker Senior Consultant
ERM TSF Ammonia emissions Reference: 0504573 Page 2 of 19
1. BACKGROUND
Hastings Technology Metals Limited (‘Hastings’) is currently developing the Yangibana Rare
Earths Project (’Project’), which is located 270 km (line of sight) east-northeast of Carnarvon on Gifford Creek Station in the Gascoyne region of Western Australia.
This air quality assessment took into consideration the 2017 (Pacific Environment, 2017) assessment, which was submitted as part of the Environmental Approvals process. Additional modelling was undertaken (ERM, 2018) to determine the stack heights of point sources within the processing plant operations.
Hastings has now engaged ERM to undertake as screening level assessment to further understand the impact of ammonia emissions from the Hydromet TSF. The screening level assessment focuses on both ambient and occupational health and safety (OHS) levels of ammonia in the surrounding environment.
2. ASSESSMENT CRITERIA
Modelled concentrations are compared to the assessment criteria to provide an objective evaluation of the impact. In the absence of criteria specific to WA, criteria adopted by other States and Territories have been referenced. For assessment criteria specific to OHS, reference is made to Safe Work Australia’s Exposure Standards. A summary of the assessment criteria adopted for this study is presented below
Table 2-1: Ambient and OHS assessment criteria for NH3
Averaging
Period
Value Unit Value
Qualifier
Source
Am
bie
nt a
ir
24-houra 104 µg/m3 Maximum Ontario Ministry of Environment (Ontario
Ministry of the Environment, 2012)
1-houra 0.33
330
mg/m3
µg/m3
99.9th
percentile
NSW EPA (NSW EPA, 2017)
3-minutea 0.6
600
mg/m3
µg/m3
99.9th
percentile
Victoria Government Gazette (Government
of Victoria, 2001)
OH
S
8-hourb 25
17a
ppm
mg/m3
Maximum Australian Occupational Exposure
Standards (Safe Work Australia, 2018)
15-minutec 35
24a
ppm
mg/m3
Maximum Australian Occupational Exposure
Standards (Safe Work Australia, 2018)
Note:
a. Values at 273K and 101.3kPa
b. Time Weighted Average (TWA)
c. Short Term Exposure Limit (STEL)
ERM TSF Ammonia emissions Reference: 0504573 Page 3 of 19
2.1 Sub-hourly Concentration Results
Dispersion model predictions results are typically presented for hourly averages. For assessment criteria shorter than one hour, the hourly concentration must be scaled to estimate the sub-hourly peak concentration. The peak concentration was calculated using a peak-to-mean ratio. The power law relation equation shown below was used to calculate the sub-hourly concentrations (CSIRO, 2008).
𝐶𝑝 = 𝐶𝑚 × (𝑡𝑝𝑡𝑚)−𝑝
where:
𝐶𝑝 = Peak concentration µg/m3 𝐶𝑚 = One hour average concentration µg/m3 𝑡𝑝 = Peak time period minutes 𝑡𝑚 = One hour time period minutes 𝑝 = Source type power law exponent -
For this assessment, the value of p was set to 0.2 for ground level sources as presented in the Katestone report Peak-to-Mean ratios for Odour Assessments (1998). For this assessment, sub-hourly concentrations of 3 and 15 minutes were required for the pollutant modelled. The peak to mean ratios used in the assessment are summarised in Table 2.2 below.
Table 2.2: Peak-to-mean ratios
Averaging Period Peak-to-mean Ratio
3 minute 1.82
15 minute 1.32
3. AMMONIA EMISSIONS
Aqueous solution of waste streams from the processing plant are sent to the Hydromet TSF at a maximum rate of 76 tonnes /hour (tph) (78 m3/hour). This stream consists of approximately 0.04 g/L of ammonium bicarbonate and 6.28 g/L of ammonium hydroxide solution and releases ammonia once it comes into contact with ambient air (GHD, 2019). The formation and release of ammonia into the atmosphere is variable and highly dependent on the pH of the incoming waste stream and the frequency of the occurrence. The conditions favouring ammonia formation follow the equilibrium equation below.
𝐻2𝑂 + 𝑁𝐻3 ⇌ 𝑂𝐻− +𝑁𝐻4−
This equation shows that a higher concentration of hydroxide ions (higher pH – more alkaline solution) will shift the equilibrium towards the formation of ammonia. The rate at which ammonia is formed, is also proportional to the temperature of the waste stream.
For the current study, a worst-case scenario of 5,300 kg/day of ammonia was considered (GHD, 2019). This presents a level of conservatism in the model. The dispersion model was then set to run with a continuous unit emission rate of 61.3 g/s.
ERM TSF Ammonia emissions Reference: 0504573 Page 4 of 19
4. MODEL SET UP
For this assessment, dispersion modelling was undertaken using the USEPA approved model AERMOD (and AERMET, for the associated meteorological component). The model set up including selection of representative meteorological year; meteorological modelling, dispersion model setup remain unchanged from the 2017 modelling study (Pacific Environment, 2017). Given the remoteness of the Project location, background ammonia concentrations were assumed negligible.
Sensitivity analysis on the source configuration suggested that a smaller surface area expression of the volume source at the TSF stream entry point would result in higher concentrations at receptors in the vicinity. For the purposes of this assessment, source was configured whereby the surface area component of the volume source has a length of 450 m. This is selected because the formation of ammonia is an equilibrium driven process (occurring over a wider area) and not confined to the mouth of the TSF. An initial vertical dimension of 0.5 m was used as the depth at which ammonia was being formed.
4.1 Receptors The model was set to predict ground level concentrations across the model domain and at nominated sensitive receptor locations. A total of 45 discrete receptors were defined (Table 4-1): these include 42 onsite receptors (i.e. receptors within the plant boundary defined for OHS purposes) and three offsite receptors (one accommodation camp and two homesteads).
Table 4-1: Discrete receptor locations (onsite and offsite)
Receptor
Id
Description Type Easting
(m, MGA50)
Northing
(m, MGA50)
1 Plant 1 Plant Thoroughfare 427,534 7,353,963
2 Plant 2 Plant Thoroughfare 427,554 7,353,910
3 Plant 3 Plant Thoroughfare 427,578 7,353,875
4 Plant 4 Plant Thoroughfare 427,607 7,353,839
5 Plant 5 Plant Thoroughfare 427,640 7,353,856
6 Plant 6 Plant Thoroughfare 427,685 7,353,889
7 Plant 7 Plant Thoroughfare 427,728 7,353,927
8 Plant 8 Plant Thoroughfare 427,671 7,353,919
9 Plant 9 Plant Thoroughfare 427,619 7,353,921
10 Plant 10 Plant Thoroughfare 427,601 7,353,953
11 Plant 11 Plant Thoroughfare 427,574 7,353,987
12 Sample Preparation
Laboratory
Plant Building 427,550 7,353,849
13 Administration Plant Building 427,626 7,353,711
14 Crib and Locker Room Plant Building 427,609 7,353,689
15 Mining Office Plant Building 427,593 7,353,709
ERM TSF Ammonia emissions Reference: 0504573 Page 5 of 19
Receptor
Id
Description Type Easting
(m, MGA50)
Northing
(m, MGA50)
16 Mining Crib and Locker Room Plant Building 428,138 7,354,329
17 Heavy Vehicle Workshop Plant Building 428,108 7,354,409
18 Accommodation Village Workers
Accommodation
421,700 7,346,593
19 Gifford Creek Station Homestead 420,600 7,340,300
20 Edmund Station Homestead 410,370 7,371,700
21 Creek 1 Existing creek 426,703 7,352,862
22 Creek 2 Existing creek 426,993 7,353,085
23 Creek 3 Existing creek 427,313 7,353,133
24 Creek 4 Existing creek 427,477 7,353,297
25 Creek 5 Existing creek 427,767 7,353,346
26 Creek 6 Existing creek 428,058 7,353,462
27 Creek 7 Existing creek 428,271 7,353,568
28 Creek 8 Existing creek 428,493 7,353,752
29 Creek 9 Existing creek 428,784 7,353,694
30 Creek 10 Existing creek 427,438 7,351,420
31 Creek 11 Existing creek 428,077 7,351,207
32 Creek 12 Existing creek 428,745 7,351,188
33 Mine Road 1 Internal mine road 429,128 7,353,090
34 Mine Road 2 Internal mine road 428,905 7,353,302
35 TSF Receptor 1 Vicinity of TSF 428,536 7,352,950
36 TSF Receptor 2 Vicinity of TSF 428,711 7,352,945
37 TSF Receptor 3 Vicinity of TSF 428,915 7,352,902
38 TSF Receptor 4 Vicinity of TSF 428,898 7,352,749
39 TSF Receptor 5 Vicinity of TSF 428,894 7,352,597
40 TSF Receptor 6 Vicinity of TSF 428,236 7,352,958
41 TSF Receptor 7 Vicinity of TSF 428,083 7,352,967
42 TSF Receptor 8 Vicinity of TSF 427,892 7,352,971
43 TSF Receptor 9 Vicinity of TSF 427,735 7,352,958
44 TSF Receptor 10 Vicinity of TSF 427,582 7,352,958
45 TSF Receptor 11 Vicinity of TSF 427,447 7,352,936
These receptors are plotted in Figure 4-1 and Figure 4-2.
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5. MODEL RESULTS
Ground level concentrations (maximum or 99.9th percentile) have been predicted across the model domain and interpreted at the nominated sensitive receptor locations. Modelled concentrations at:
offsite receptors have been compared to ambient air quality criteria.
onsite receptors have been compared to the relevant OHS guideline
5.1 Modelled results at offsite receptors Modelled 1-hour, 24-hour and 3-minute average concentrations at offsite sensitive receptors are compared against ambient criteria in Table 5-1. The results indicate that concentrations predicted across three offsite receptors are well within the ambient air quality criteria.
Table 5-1: Modelled concentration at offsite receptors
Receptor
Id
Description Type 1_houra
(µg/m3)
24_hourb
(µg/m3)
3_minutea
(µg/m3)
18 Accommodation Village Workers
Accommodation 28 7 51
19 Gifford Creek Station Homestead 19 5 34
20 Edmund Station Homestead 4 4 7
Ambient Air Quality Criteria 330 104 600
Note:
a. 99.9th percentile value
b. maximum value
Contour plots of 1-hour 99.9th percentile; maximum 24-hour and 3-minute 99.9th percentile concentrations are presented in Figure 5-1, Figure 5-2 and Figure 5-3 respectively.
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5.2 Modelled results at onsite receptors Modelled 8-hour and 15-minute average concentrations have been compared against relevant OHS guideline and presented in Table 5-2. Contour plots for 8-hour and 15-minute averages are presented in Figure 5-4 and Figure 5-5 respectively.
The results indicate that the 8-hour criteria was met at all 42 onsite receptors; 15-minute criteria was met at all 42 onsite receptors, except one (TSF Receptor 1, 25.8 mg/m3). It should be noted that the second highest value (15-minute) predicted at this receptor was 12.2 mg/m3 at about 50% of the criteria (24 mg/m3). This is an indication that the likelihood of this predicted excursion is low.
Table 5-2: Modelled concentrations at onsite receptors
Receptor
Id
Description Type 8_hour
(mg/m3)
15_minute
(mg/m3)
1 Plant 1 Plant Thoroughfare 0.53 1.81
2 Plant 2 Plant Thoroughfare 0.54 1.90
3 Plant 3 Plant Thoroughfare 0.56 1.96
4 Plant 4 Plant Thoroughfare 0.58 2.03
5 Plant 5 Plant Thoroughfare 0.61 2.06
6 Plant 6 Plant Thoroughfare 0.65 1.98
7 Plant 7 Plant Thoroughfare 0.64 1.95
8 Plant 8 Plant Thoroughfare 0.64 1.91
9 Plant 9 Plant Thoroughfare 0.58 1.97
10 Plant 10 Plant Thoroughfare 0.57 1.92
11 Plant 11 Plant Thoroughfare 0.55 1.87
12 Sample Preparation
Laboratory
Plant Building 0.62 1.98
13 Administration Plant Building 0.87 2.12
14 Crib and Locker Room Plant Building 0.98 2.20
15 Mining Office Plant Building 0.95 2.16
16 Mining Crib and Locker
Room
Plant Building 0.63 4.49
17 Heavy Vehicle Workshop Plant Building 0.59 4.36
21 Creek 1 Existing creek 0.32 1.51
22 Creek 2 Existing creek 0.54 4.42
23 Creek 3 Existing creek 0.53 3.69
24 Creek 4 Existing creek 0.81 2.39
25 Creek 5 Existing creek 1.54 2.96
26 Creek 6 Existing creek 1.03 3.17
27 Creek 7 Existing creek 1.48 10.15
ERM TSF Ammonia emissions Reference: 0504573 Page 13 of 19
Receptor
Id
Description Type 8_hour
(mg/m3)
15_minute
(mg/m3)
28 Creek 8 Existing creek 0.62 2.62
29 Creek 9 Existing creek 0.73 2.76
30 Creek 10 Existing creek 0.45 3.95
31 Creek 11 Existing creek 0.25 0.74
32 Creek 12 Existing creek 0.40 0.79
33 Mine Road 1 Internal mine road 0.89 3.22
34 Mine Road 2 Internal mine road 1.21 3.89
35 TSF Receptor 1 Vicinity of TSF 6.45 25.75
36 TSF Receptor 2 Vicinity of TSF 2.95 7.43
37 TSF Receptor 3 Vicinity of TSF 1.65 5.51
38 TSF Receptor 4 Vicinity of TSF 2.00 6.04
39 TSF Receptor 5 Vicinity of TSF 2.52 14.44
40 TSF Receptor 6 Vicinity of TSF 4.14 10.69
41 TSF Receptor 7 Vicinity of TSF 2.36 5.91
42 TSF Receptor 8 Vicinity of TSF 1.34 7.00
43 TSF Receptor 9 Vicinity of TSF 1.06 7.73
44 TSF Receptor 10 Vicinity of TSF 0.94 7.14
45 TSF Receptor 11 Vicinity of TSF 0.86 6.18
Maximum across onsite receptors 6.45 25.75
OHS criteria 17 24
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Further analysis was undertaken to identify the meteorological/dispersion conditions that give rise to the exceedance at TSF Receptor 1. The findings are presented in Table 5-3. Meteorological parameters investigated include atmospheric stability, wind speed and wind direction.
The results infer that the exceedance is predicted to occur during calm conditions just before sunrise and was associated with low inversion layers and wind direction blowing from the source, towards the receptor.
Table 5-3: Meteorological conditions that led to 15-minute excursion at TSF Receptor 1
Timestamp 15-min concentration (mg/m3) Stability Wind speed (m/s) Wind direction
06/06/2011 01:00 3.93 Very Stable 0.8 232
06/06/2011 02:00 4.86 Very Stable 0.7 225
06/06/2011 03:00 7.87 Very Stable 0.5 217
06/06/2011 04:00 8.34 Very Stable 0.5 198
06/06/2011 05:00 6.29 Very Stable 0.9 182
06/06/2011 06:00 5.33 Very Stable 1.1 174
06/06/2011 07:00 5.68 Very Stable 1 171
06/06/2011 08:00 25.75 Very Stable 1.2 165
06/06/2011 09:00 1.00 Unstable 1.8 160
06/06/2011 10:00 0.83 Unstable 1.9 157
06/06/2011 11:00 0.77 Unstable 1.9 158
06/06/2011 12:00 0.87 Unstable 2 163
5.3 Occurrence of worst case meteorology Additional investigation was undertaken to understand the hourly concentrations trends to aid in monitoring of NH3 for OHS purposes should this be determined necessary. Analysis included concentration trends based on period (month), time of day, wind speed and atmospheric stability. The following can be observed:
Higher concentrations are generally associated with lower wind speeds and very stable atmosphere.
Concentrations start to increase from 4 pm in the evening reaching maxima around 10 pm and starts to drops after 6 am in the morning.
Generally higher concentrations are predicted between July to October.
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Figure 5-1: Predicted hourly concentration trends - month
Figure 5-2: Predicted hourly concentration trends – time of day
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Figure 5-3: Predicted hourly concentration trends – wind speed
Figure 5-4: Predicted hourly concentration trends – atmospheric stability
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6. REFERENCES
CSIRO. (2008). Calculate Peak to Mean Ratio. Retrieved from CSIRO Marine and
Atmospheric Research: https://www.cmar.csiro.au/airquality/peaktomean.html
ERM. (2018). Yangibana RAre Earths Project Plume Study.
GHD. (2019). Yangibana Hydromet Tailings Storage Facility (TSF) Ammonia Gas Modelling
Results.
Government of Victoria. (2001). State Environment Protection Policy (Air Quality
Management), No. S 240,. Victoria Government Gazette.
Katestone. (1998). Peak-to-mean Ratios for Odour Assessment. Report from Katestone
Scientific to Environment Protection Authority of New South Wales. Katestone
Scientific.
NSW EPA. (2017). Approved Methods for the Modelling and Assessment of Air Pollutants in
New South Wales. New South Wales EPA.
Ontario Ministry of the Environment. (2012). Ambient Air Quality Criteria (AAQCs). Standards
Development Branch Ontario Ministry of the Environment.
Pacific Environment. (2017). Final Report - Yanibana Rare Earths Project - Air Quality
Assessment - Doc No AQU-WA-005-21519. Pacific Environment Limited.
Safe Work Australia. (2018). Workplace Exposure Standards for Airbourne Contaminants.
Safe Work Australia.
GHD
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© GHD 2019
This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited.
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