Source document: https://docs-lawep.s3.us-east-2.amazonaws.com/1698832077387.pdf (Malaysia)
Lynas Advanced Materials Project: Conceptual Design for Residue Storage Facility - Gebeng LYNAS MALAYSIA SDN BHD Lynas Advanced Materials Project Conceptual Design for Residue Storage Facility - Gebeng 4219298-300-EN-RP-101 Rev.1 16-Jan-08 Level 7, QV1 Building 250 St Georges Terrace Perth WA 6000 Australia Tel: +61 8 9278 8111 Fax: +61 8 9278 8110 www.worleyparsons.com WorleyParsons Services Pty Ltd ABN 61 001 279 812 © Copyright 2008 WorleyParsons Services Pty Ltd LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG SYNOPSIS arsons Services Pty As part of the Advanced Materials Project to be constructed in Malaysia, WorleyP r a residue storage Ltd was request by Lynas Malaysia Sdn Bhd to prepare a conceptual design fo ristics and disposal facility using ‘base case’ conditions.
Based on anticipated residue characte of the project was conditions, the volume of residue produced per annum and over the lifespan rds the creation of a calculated and used in conjunction with a waste strategy/philosophy directed towa chnically stable and environmentally neutral long-term storage facility.

Potential re-use of geote proces s by-products and post-closure potential site development were emphasised in the conceptual design.
The conceptual design of the residue storage facility is described in terms of design objectives, design parameters and assumptions, facility operation and conceptu al design details and drawings.
Disclaimer een prepared on behalf of and for the exclusive use of Lynas Malaysia Sdn Bhd, and This report has b is subject to and issued in accordance with the agreement between Lynas Malaysia Sdn Bhd and WorleyParsons Services Pty Ltd. WorleyParsons Services Pty Ltd accepts no liability or responsibility whatsoever for it in respect of any use of or reliance upon this report by any third party.
Copying this report without the permission of Lynas Malaysia Sdn Bhd or WorleyParsons Services Pty Ltd is not permitted.
PROJECT 302/14205 - LYNAS ADVANCED MATERIALS PROJECT REV DESCRIPTION ORIG REVIEW WORLEY- PARSONS APPROVAL DATE CLIENT APPROVAL DATE 0A Issued for internal review N/A 19-Oct-07 N/A 0B Issued for Information 0C IFR and IFI to Environ P Baker/W Miller T Loh/S Rutkowski P Baker/W Miller T Loh/S Rutkowski N/A P Baker/W Miller T Loh/S Rutkowski N/A 12-Nov-07 10-Jan-08 N/A N/A 1 Approved for Construction 16-Jan-08 N/A T Loh/S Rutkowski N/A P Baker/W Miller r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300- en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page ii LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG CO NTENTS 1.
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Introduction ...................................................................................... ... ........................ ....1 .. Project Description ........................................................................................................... 3 Waste design volume and surface areas ...................................... .. .
....................... .... ...5 3.1 Quantity of Waste Generated ............................................................ .. .

....................... .... ...5 3.2 RSF Footprint Area ............................................................................ .. .

..............................6 Waste Management Strategy/Philosophy ..................................... .. .
........................ ....7 .. 4.1 Potential Reuse of Residue Streams.................................................................................. 7 4.2 Post-Closure Potential Site Development .......................................................................... 7 4.3 Surface Water Runoff ...................................................................... ... .. ....................... .... ...8 Expected subsurface Conditions................................................. ... ............................10 .. 5.1 Subsurface Ground Conditions........................................................ ... ........................ ..10 .. .. 5.2 Groundwater .....................................................................................................................12 Conceptual Design and Description of RSF ............................... ... .. ....................... .... .13 6.1 Design Objectives ............................................................................ ... .. ....................... .... .13 6.2 Design Parameters and Assumptions ............................................. ... ............................13 .. 6.3 Residue Facility Design for NUF, FGD and WLP ............................ ... ............................14 .. 6.4 Facility Operation for NUF, FGD and WLP.......................................................................15 Preliminary Assessment of Embankment Slope Stability..........................................17 Recommendations for Further Investigation and Analysis .......................................20 Information on Interpretation, Use and Liability of This Report ................................21 10.
References.......................................................................................................................22 Figures and Drawings r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page iii 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG 1.
INTRODUCTION The project is for the development of the Advanced Materials Plant by Lynas Malaysia Sdn Bhd for the production of high purity lanthanide compounds within the Gebeng Industrial Estate (GIE), Kuantan State, Malaysia.

The raw material is poly-metallic Lanthanide Concen mine in Western Australia, which will be imported through the sea port at Kua the plant by road.
ntan and delivered to trate from the Mt Weld Corpor ation Ltd. is a publicly traded company listed on the Australian Stock Exchange and is Lynas involved in the production of Lanthanide products.

The Advanced Materials Plant will consist of a num ber of processing are as: 1.

Cracking & Sep aration Plant, consisting of the sections; Cracking; Waste Gas T reatment; L eaching (primary, secondary, tertiary); Upstream Extraction; D ownstream Extraction; Product Finishing; 2.

Utilities; 3.
Utilities; 3.

Water Treatment and Residue Management; and 4.

Off-plot.

The Concentration Plant (to be located in Mt.


Weld, Western Australia) will pr Lanthanide Concentrate which is the feedstock for the Cracking & Separation P the C oncentration Plant, the ore will be processed via crushing, ball milling, flotation (rougher, scavenger and cleaner cells), concentrate thickening and filtration, and tailings dewatering and storage to obtain an Iron Oxide Material (IOM) residue and a Lanthanide Concentrate.

oduce an intermediate lant (C&S Plant).


In Lanthanide Concentrate will be transferred to the Advanced Materials Plant within the GIE in Malaysia where it is subjected to the cracking and separation process involving concentrated acid in a rotary kiln and water leaching of the calcine.

Following three stages of leaching and solid-liquid separation, solvent extraction will be used to separate, purify and concentrate the lanthanide elements.
The r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 1 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG lanthanide elements are finally precipitated and calcined to produce a range of carbonate and oxide products.
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PROJEC T DESCRIPTIO N The Advance d Materi Western Australia, at provide cess is th e pro als Project involves proces a processing site that utilis d in WorleyParsons rep si es ort 1 ng lanthanide co chemical treatm 3229-PM-RP-001 (2007 ).

ntrate fro nce ent processes.

A description of m Mt.

Weld in As a result of the lanth lphuris s Desu Flu Purification residue (W e Ga anide concentrate processi utra ation residue (FGD); Ne LP).
ng, three separa lisation Underflow residue (N te residue streams are produced; UF); and Water Leach ams (FGD, NU The three residue stre F, and WLP) are subjected to pressure filtration and assumed to be in paste form (moisture contents between 30% and 40%), once processed and ready for storage in the Residue Storage Facility (RSF).

Residues with moisture content between 30% and 40% are often referred to as paste.
Rheological testing on the paste residue streams expected from the process plant indicates that the paste residues are not suitable for pumping.

Therefore, the FGD, NUF and WLP residue streams will be transported by vehicle, deposited, spread and traffic compacted to form the respective residue deposits.

This type of residue storage produces a stable land-form and reduces the seismic risk for the RSF.
A summary of the three residue streams in terms of anticipated disposal conditions, surface water runoff management, lining requirements and potential residue end use is provided in Table 1.

These topics will be discussed in greater detail in later sections of this report.
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WASTE DESIGN VOLUME AND SURFACE AREA S 3.1 Quan tity of Waste Generated The anti generate cipated annual dry mass and volume of residue per ann d by the lanthanide extrac tion p rocess for the three streams is summarised in Table 2. um over a 10 year project lifespan Table 2: Average Quantities of R rated Residue Stream Annual Dry Mass Year 1 (tpa) esidue Gene Assumed Dry Density (t/m3) FGD NUF WLP 27,900 85,300 32,000 1.05 1.05 0.70 Annual Volume Year 1 to Year 2 (m3) Annual Volume Year 3 to Year 10 (m3) 10 Year Volume (m3) 26,600 53,200 478,800 81,300 162,600 1,463,400 45,800 91,600 824,400 Total 145,200 153,700 307,400 2,766,600 Annual dry residue mass for each stream is subject to change (decrease and increase) pending further refinement of the processing systems.
The base case RSF design assumes that the FGD, NUF, and WLP residue streams will undergo dewatering resulting in paste for deposition and storage within the RSF.
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No.

302-14205-CI-D all three residue streams assuming 8m high emban No.
302-14205-CI-DSK-0001 the approximate ava summarised in Table 3. kments.

Based on the configuration shown in Drg.

ilable surface area for residue storage is SK-0001 presents the conceptual RSF layout configured for the storage of was developed.
Table 3: Approximate Surface Area for each Residue Stream Residue Stream Approximate Surface Area Available for Residue Storage (m2) FGD NUF WLP Total 46,000 154,000 80,000 280,000 The surface areas presented in Table 3 are approximate (±10%) and will require further refinement as the RSF design proceeds.

Further modifications to overall layout, RSF emban pond sizing, and use of dried compacted residue as construction materials a surface area requirements.

The RSF footprint a for reprocessing or sale.


kment configuration, re ongoing to minimise rea may also be reduced by reclamation of residues r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 6 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG 4.
WASTE MANAGEMENT STRATEGY/PHILOSOPH Y The waste management strategy for the three residue streams is directed environmentally-neutral long-term storage facility by means of a RSF design which maximise potential recycling of process by-products.

Even if by-products are not utilised design will be capable of permanent stor stable and useful final landscape.
in the future, the RSF age (for the period of 5-6 years) of the residue and result in a towards the creation of an s the 4.1 Potential Reuse of Residue Streams An alternative approach to long-term storage of residue is the potential reuse of the waste streams by r all) of them.

The latter approach regards the residue identifying potential beneficial uses for some (o and other materials generated by the project as by-products rather than waste.
This approach has been explored for the various residue streams generated by the Advanced Materi (WorleyParsons Report No.

13229-PM-RP-001, 2007) and the results are su mmarised below.

als Project Each of the residue types has a high magnesium and phosphorus content, and therefo used in the fertiliser industry.
re may be The FGD stream, consisting predominantly of gypsum (manufactured calcium s useful sales in the Malaysian plasterboard market, although the product would n both virgin gypsum and a range of other (similar) by-product or manufacture ulphate) could find eed to compete with d gypsum types.

The NUF residue contains a high level of magnesium.

Although the content of a considered desirable, the calcium sulphate is considered to complement the materials.
luminium may not be The WLP residue also contains relatively high levels of the nutrients phospho rus and magnesium.

Residues may need to be stored until processing and sale of the materials becomes viable.

Accordingly, the residues need to be stored with an emphasis on future maintaining environmental controls and geotechnical stability.
commercially availability while 4.2 Post-Closure Potential Site Development Post-closure site development options have been explored and are summarised in WorleyParsons Report No.

13229-PM-RP-001 (2007).

Potential land use options identified include residential, agricultural, industrial, recreational, and commercial.

The preferred option is to establish a stable landform suitable for industrial development.
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pendent on the height of d existing ground A layout using cellular design maintaining separation of the three residue streams an posed.

This will satisfy the condition of accessibility to the stored residue end of the project is pro materials should sale of the materials become economically viable in the future.
The height of the embankments is currently limited to 8m in order to achieve a stable landform (pendin geotechnical assessment of residue properties, embankment parameters and existing groun conditions).

This may allow use of the site as a commercial/industrial area pending con environmental and geotechnical constraints dependent on the type of development proposed if the alternative of sale of stored residue is not pursued.
g further d sideration of d capped at the Should material properties of the residue streams be such that a final land mass without sufficient stiffness to support typical commercial or industrial structures be achievable, the RSF area will be able to provide passive and recreational end uses once capped for permanent storage and environmental conditions (if any) are satisfied.
4.3 Surface Water Runoff The surface water management system for the RSF will comprise a segregated system from that designed for the process plant.

Surface water from the RSF area will not mix with surface water from the process plant area.

Any supernatant liquors and rainfall runoff associated with RSF cells will report to dedicated RSF retention ponds prior to return to the waste water treatment facility (WWTF) or to the cracking and separation process in the case of the WLP storage cells.
Water will be treated to meet approved criteria and ultimately released off-site.

During operation the surface of active FGD, NUF and WLP residue containment cells will be continuously contoured by earthmoving equipment to a slope of approximately 100H:1V as residue are placed and compacted to direct surface water towards a single supernatant/surface runoff pond within the RSF cells.

The WLP containment cell will have a separate dedicated surface water retention pond.
nfall runoff from the FGD and NUF residue will be directed or pumped via Supernatant liquors and rai pipeline to a common high density polyethylene (HDPE) lined surface water retention pond with capacity for the 1 in 100 year storm event based on climatic data for the region.

Water from this pond will be returned to the nearest pipeline access point for return to the WWTF in the process plant.

Water from the WWTF will be assessed against approved criteria and ultimately discharged off-site.
Surface water runoff must be removed from the RSF cells within days of accumulation to prevent the residue mass from absorbing water and resulting in a residue surface that is untrafficable for r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 8 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG extended periods of time limiting placement of residue within RSF cells.
The FGD/NUF surface water retention pond will be sized to accommodate th processed by the WWTF.

ese potential water volumes until this water can be The composition of supernatant liquors and surface water runoff from the WLP re expected to be suitable for release back into the environment.
Instead this water stream will be recycled into the cracking and separation process stream and as such, s directed or pumped to a separate HDPE-lined surface water retention pond w 100 year storm event based on climatic data for the region.

Supernatant liquors from the WLP residue will b cracking and separation facility.
e pumped via pipeline to the nearest pipeline access point for return to the ith capacity for the 1 in and rainfall runoff urface water runoff will be sidue is not At closure, residue cells will be capped wi into the permanently stored residue mass and a landform will h ave been created with positive surface drainage.
Surface water runoff from capped cells will not interact with stored residue and the final site topography will encourage surface water to drain off-site to prevent ponding and standing water.
th suitable low-permeability materials to prevent infiltration r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 9 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG 5.
EXPECTED SUBSURFACE CONDITIONS 5.1 Subsurface Ground Conditions cal sit A geotechni interpretation and a results will provide geote e investigati on ssessment of test pit at the Gebeng site has recently been carried out and the and borehole logs, soil samples, and laboratory testing chnical parameters required for the final RSF design.
Ground conditions within the upp uppermost two horizons – the fill and underlying organic clay are continuous across the site while s in the m there are lo may be lensed and discontinuou arine/alluvial horizons beneath the organic s. er 4m of the soil profile are consiste nt across the site.

The cal var clay where the materials iation Prior to placement of general fill, vegetation, tree stumps and roots were removed.

Placement of fill go and elve months.


The fill was comm won from local borrow and comp earthworks continued for approximately tw rises two mai enced four n types: years a • Lateritic Fill: Clayey sandy gravel with distinctive red-bro wn colour: and • Sandstone Fill: Clayey g ravelly sand.

Clayey gravelly sand is the domi l of me coarse, su sandstone and is yellow-brown in bangula r grave nant fill type used on dium strength sandstone.

The fill contains occa colour.

site.


The gravel component consists of fine to sional cobbles of Across the site, the depth to the base of the fill varies from 0.8m to 1.8m (ave SPT N-values of between 4 and 10 the material is loose – suggesting that the fil traffic compacted.

rage 1.3m).

Based on l was placed and The fill was placed over the in situ swampy soil comprising very soft medium plasticity organic clay which can vary in thickness from 0.6m to 1.7m.
This unit contains softened roots up to 20 mm diameter throughout and occasional tree trunks up to 1.5m long and 0.3m thick.

Hand shear vane tests returned undrained sh to soft consistency.

The organic clay generally grades into a non-organic medium plastic green- brown soft clay of alluvial origin, otherwise the organic clay is directly underlain by blue-grey or light grey silty/clayey sand believed to have been deposited in a shallow-marine setting.
ear strength values between 7 kPa and 15 kPa corresponding to very soft The silty/clayey marine sand was encountered in the majority of test pits with a variable thickness between test pits from 0.3m to greater than 2.1m (and extending beyond the depth of the test pit).
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Where slow seepage of g was observed, the marine sand began to slump suggesting the material has low cohesion.
roundwater The marine sand is underlain by dark grey-brown sandy clay.

Interpreted as al is soft with medium plasticity.

luvial clay, the material Ground conditions within the upper 4m of the subsurface profile is summarised in Table 4.
Table 4: Summary of Subsurface Profile (to 4.5m depth) Geological Unit Depth to Base of Unit General Description Fill Up to 1.8m Clayey gravelly SAND, yellow-brown, medium strength sandstone gravel, moist, loose; locally clayey GRAVEL, red-brown, ironstone gravel, moist, loose.

Swamp Deposit 3.0m Silty CLAY, low to medium plasticity, dark grey, soft roots throughout, high organic content, very soft to soft.
Thickness 0.6 to 1.7m Alluvium >4.2m Silty CLAY, locally sandy, green-brown, medium plasticity, soft.

Thickness 0.2 to >2.2m Marine Sand >4.2m Silty/Clayey SAND, fine to medium grained, blue-grey and light grey, loose, medium plastic fines.

Thickness 0.3 to >2.1m Alluvium >4.2m Silty/Sandy CLAY, medium plasticity, dark grey-brown, moist, soft.
Short-term (total stress) and long-term (effective stress) design parameters in terms of undrained shear strength, bulk density and friction angle have been estimated based on the visual assessment of materials and in situ tests (hand shear vane and standard penetration tests) to provide data required for the preliminary assessment of embankment stability discussed in Section 7. r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 11 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG 5.2 Groundwater In all test pits excavated, only minor seepage of groundwater was encountered in the upper 3.5m of the soil profile, with the water believed to be present in isolated sandy lenses wi thin the organic clay and underlying units.
Where encountered in the test pits, slow but steady seepage of wat 3.5m depth.

Four test pits were left open up to 3 days and the water level monitored.

After 2 days, the water level in the pits had risen to between 1.3m and 2.5m depth below gro er into the pits occurred below und level.

Seven monitoring wells are present around the site.

The water levels in the wells at the time of the investigation were between 0.95m and 3.5m below ground le vel.
The observations in the test pits and monitoring wells suggest that the water ta and 4.0m depth.

The organic clay and penetrated by a borehole or test pit allows the water to rise to a piezometric level that in places is less than 1m below ground level.
underlying clay horizon may act as an aquitard that once ble is between 3.5m r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 12 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEB ENG 6.
CONCEPTUAL DESIGN AND DESCRIPTION OF RSF 6.1 Design Objectives The RSF will be designed for environmentally acceptable and geotechnically stab permanent storage of all three residue streams.

The design will also accom to stored residue should markets for the materials be identified in the future.

A du high density polyethylene (HDPE) overlying a compac implemented to minimise potential migration of leachate from the RSF cells.
ted low-permeability clay liner will be le long-term modate potential access al liner system of Another important objective of the design is the implementation of a water ma supernatant liquor and surface water runoff from RSF containment cells.

The RS management system will incorporate contoured residue surfaces, dedicated rete ultimately water return to the process plant area for either the waste water treatment facility (WWTF) before being discharged off site.
nagement system for F water ntion ponds and recycling within the process or treatment in It should be noted that the following conceptual design requires complete geote and analysis in terms of existing ground conditions and residue properties to e performance throughout the lifespan of the fac ility.
chnical assessment nsure satisfactory 6.2 Design Parameters and Assumptions Production parameters used for the RSF design are discussed in Section 3 and pre The RSF design includes the following assumptions: sented in Table 2.

• Fill may be added as required to ensure that depth to groundwater from the botto RSF is more than 1m and the RSF design will ensure that residue solid direct interaction with groundwater.
This soil layer comprising fill underly be an unsaturated zone inhibiting potential contaminant migration.

m of the s are isolated from ing the RSF would • The FGD, NUF, and WLP streams will have a paste consistency at a moisture content between 30% and 40%.

These residues will be stockpiled and allowed to air-dry to achieve a moisture content of less than 25% before being spread and traffic compacted with a front-end loader and dozer.
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Drg 302-14 FGD and WLP RSF cells are shown on Drg.

Nos.

0002, 0003 and 0004, respectively.

205-CI-DSK-0001 presents the RSF final layout.

Typical embankment sections for the NUF, ty (when the embankment currently predicted to .

No.

The RSF has been designed as a paddock-style facility with a final perimeter em 8m in height.
Initially, RSF cells will be constructed on existing fille with storage capacity for one years’ production of the res cells to increase storage capacity will be constructed base predictions throughout the lifespan of the facility.

Final embankment heights ar confirm slope stability, settlement and other geotechnical constraints pective residue streams.
Additional adjoining d on filling curves and staged storage e subject to analysis to bankment limited to d ground for each residue stream Suitable fill material with required geotechnical properties will be used for the initi construction.

Downstream perimeter walls have been designed with a 3H:1V batter slope – an angle considered consistent with the desire to establish a stable long-term landform.

E such as coarse rock (rip rap) or geotextile will be required for perimeter walls.
has been chosen but can be modified to suit the envisaged construction equipm and divider wall batter angles have been designed at 2H:1V with the exception slopes which will be at 3H:1V to optimise liner construc ent.

Upstream slope of the initial upstream rosion protection A crest width of 4 m tion effectiveness.

al embankment Foundation soils beneath the embankment footprint should be scarified an placement of embankment fill.
Depending on ground conditions, it may be necessary to scari recompact the foundation soils in the basin areas to establish a trafficable platfor commence dual liner construction and residue placement.

Fill will be added as depth to groundwater from bottom of RSF is more tha m on which to required to ensure d recompacted prior to n 1m.
fy and Embankment raises will take place on an annual basis as additional storage c Centre-line embankment raises will be used for FGD and NUF containment cells utilising placed NUF and FGD residue (WLP will not be used as construction materials for environm ental reasons).

Use of the NUF and FGD residue as construction materials is provisional pending geotechnical assessment of the material properties.
The FGD and NUF residue will be deposited as paste and will require air- drying prior to use as an em bankment fill.

Air-dried residue should be compacted to 98% standard maximum dry density or 95% modified maximum dry density, and at optimum moisture content.

apacity is required.

A downstream configuration will be used for embankment raises for the WLP cells.
This will allow a continuous implementation of the dual liner system (described below) across the cell floor all the way along the downstream embankment face to the final height of the embankment at which time the cell will be capped for closure.
r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 14 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG Containment of residue liquor will be maintained using a dual liner system (Drg.

Nos.
Nos.

302-14205-CI- DSK-0002, 0003 and 0004 - Detail A) consisting of a 300 mm low-permeability compacted clay liner overlain by a 1.0 mm thick high density polyethylene (HDPE) liner.

These liners are expected to isolate solid residues via a relatively low-permeability barrier and lower the risk of migration of any potential leachate into the groundwater.

A 300mm thick ‘cushion layer’ will be placed atop the dual liner system to limit the potential for damage to liners by prolonged exposure (e.g.
to ultraviolet radiation) and during construction and potential reclamation operations.

This cushion layer should have a distinct colour difference from the residue to provide adequate warning for earthworks operators of proximity to the underlying liners when working or excavating residues for sale to local industries.

At some point in the future, residue materials could be reclaimed from previously completed RSF cells and the emptied cells re-used for residue storage.
Care and attention to the cushion layer should be exercised during reclamation operations to prevent damage to liners.

6.4 Facility Operation for NUF, FGD and WLP NUF, FGD and WLP residues will be placed and traffic compacted within the RSF cells with a front- end loader and dozer envisaged for this operation.
The residues can therefore be placed and trimmed to establish surface contours such that pond water will be directed to the appropriate facilities either using lined diversion channels or pumped back from a pontoon-mounted pump or permanent decant structure.

The NUF, FGD, and WLP residues will require air-drying prior to being spread and traffic compacted as it arrives at the RSF as paste.
Material can be stockpiled within the RSF, periodically reworked with the dozer until the material is sufficiently dry (moisture content less than 25%) to be suitable for spreading and traffic compaction.

If climatic conditions are unsuitable for open air drying, drying sheds with storage capacity for the wet season may be required.

Residues will require turning and mixing within the sheds to allow even drying of the materials.
During heavy rainfall and in particular the monsoonal wet season the surface of the residue is expected to become wet, soft and slippery making placement of residue during this period problematic due to the poor trafficability of the residue surface.

Therefore, a temporary cover may be required to keep the area o f active residue placement dry during the wet season.
A potential solution to this problem is to size the drying shed with sufficient capacity so residue can be stockpiled during the wet season awaiting placement in the RSF during drier weather.

As part of the fill/construct methodology for the RSF, cells will be capped once design capacity is achieved creating a landform with positive drainage.
Capping is envisaged to comprise a 500mm thick rock-fill layer to serve as a capillary break, overlain by low permeability clayey soil and topsoil to lower the risk of infiltration.
Interaction between rainfall and surface water runoff from capped cells r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 15 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG and permanently stored residues will be minimised and the final site topography will encourage surface water to drain off-site to prevent ponding and standing water.
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PRELIMINARY ASSESSMENT OF EMBANKMENT SLOPE STABILITY nary e counte A prelimi profile en the factor of safety (FOS) of slopes against global failure.
ent slop conducte ability assessment has b ng the site investigation and estimated design pa mbankm red duri een e st d b ramete ased on the subsurface rs in order to ensure Four cases were considered in the stability assessment, as follows: Case 1a: Short-term undr This anticipated normal groundwater table conditions.
ained (normal ediate sh esents the imm case repr groun ort-term con ion after the em dwater level) dit bank ment is raised under e 1b: Shor t-term undrain Cas This case represents the immediate short-term condition after the embankment is raised and includes the ted groundwater level) groundwater levels.
influence of sea ed (eleva sonal var iation in Case 2a: Long-term drained (normal groundwater level) This case represents the long-term condition after the embankment is raised und groundwater table conditions.

er anticipated normal Case 2b: Long-term drained (elevated groundwater le This case represents the long-term condition after the embankment is raised and includes the influence of seasonal variation in groundwater levels.
vel) The adopted soil parameters for both short-term and long-term stability analysis are presented in Tables 5 and 6 respectively.
Table 5: Adopted Slope Stability Analysis Soil Parameters for Imported Material Material Above Subsoil Unit Weight (γ) Cohesion (c’) Angle of Friction (φ’) Residue Embankment Raise Initial Embankment Fill General Fill 1.2 t/m3 1.5 t/m3 1.9 t/m3 1.9 t/m3 0kPa 0kPa 0kPa 0kPa 20° 28° 34° 30° r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 17 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG Table 5a: Adopted Subsoil P arameters for Slope Stability Analyses (Short-Term Undrained) Su soil Mate b rial Soft Clay 1 Soft Clay 2 Soft Clay 3 Soft Clay 4 Unit Weight (γ) 1.65t/m3 1.65t/m3 1.65t/m3 1.65t/m3 Undrained Shear Strength (kPa) Initial 2m high embankment Raise 1 : 4m high embank ment Raise 2 : 6m high embankment Raise 3 : 8m high embankment 7 11 7 11 10 14 10 14 13 17 13 17 16 20 16 20 Table 5b: Adopted Subsoil Parameters for Slope Stability Analyses (Long Term Drained) Material Unit Weight (γ) Cohesion (c’) Angle of Friction (φ’) Soft Clay 1 Soft Clay 2 Soft Clay 3 Soft Clay 4 Clayey Sand 1.65t/m3 1.65t/m3 1.65t/m3 1.65t/m3 1.8t/m3 4 4 4 4 0 21° 21° 21° 21° 32 The stability analyses were conducted using Slope W software and the factor of safety (FOS) against global failure on the embankment slopes was checked using the Morgenstern Price method for circular failure mode.
A summary of the slope stability analyses is presented in Table 6. r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 18 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG Table 6: Summary of Slope Stability Analyses Circular Failure Embankment Height Initial - 2m 1st raise - 4m 2nd raise - 6m 3rd raise - 8m NC – Non-critical Factor of Safety (FOS) Short Term Undrained Long Term Drained Normal Water Level 1.57 1.23 1.22 1.27 Full Water Level 1.57 1.23 1.22 1.27 Normal Water Level NC 1.7 1.7 1.7 Full Water Level NC 1.64 1.63 1.62 In accordance with ANCOLD (Australian National Committee On Large Da FOS for short-term and long-term stability are 1.3 and 1.5, respectively.
As can b 6, the FOS against global failures for embankment height up to 8m is acceptab case but not the short term case.

ms) guidelines the required e seen from Table le in the long term The preliminary slope stability assessment indicates that the proposed embankm ent fill height of 8m results in a FOS of less than the acceptable minimum of 1.3 under short-term u ndrained conditions.

This can be overcome by the placement of an additional 1.0m of well compacted select fill across the RSF area.
Further assessment of the consolidation behaviour of the subsurfac confirm the short-term stability o e soils is required to f the embankments.

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RECOMMENDATIONS FOR FURTHER INVESTI ANALYSIS GATION AND The conceptual design for the RSF described in this report is based on preliminary data with respect to existing ground conditions, residue characteristics and disposal methods.
A progresses, the following recommendations should be consid s design of the RSF ered: • Residue behaviour will be influenced by water content, dominant particl e size and shapes, mineral composition, size distribution, temperature, pressure, particle interaction, and compacted density.

These properties will have an influence on the in terms of workability and long term behaviour over the lifesp determined and considered in greater detail during RSF design.
behaviour of the residue an of the project and should be • The dispersive nature of the residue should be determined and its impact on the RSF design analysed.

• Ground conditions across the site should be assessed based on data obtained from the recently completed site investigation and subsequent laboratory testing programme.

• The groundwater regime below the proposed site of the RSF needs to be confirmed.

A site- specific hydrogeological investigation should be considered.
• This conceptual model will require detailed settlement and slope stability including seismic sensitivity analyses to ensure the stability of the landform created.

Based on these analyses recommendations for soil improvement across the RSF foundation area may be required to achieve acceptable factors of safety.

• RSF surface water retention ponds will require sizing to accommodate monsoon and storm events over the life of the project.
• The suitability of in situ soils at the site for use as embankment fill and general fill should be confirmed or alternative sources of material identified.

• Currently area available at the proposed site designated for the RSF has a predicted storage capacity of approximately 5 to 6 years’ residue production.
Options such as reuse or sale of residue by-products, chemical addition to improve achieved density of residue placed in the RSF cells and/or acquisition of additional land needs to be considered for a 10 year project lifespan.
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INFORMATION ON INTERPRETATION, THIS REPORT USE AND LIABILITY OF his report has been prepared in accordan ce with a specific brief and scope of work.
It should be T read in its entirety.

he responsibility of WorleyParsons is solely to Lynas Malaysia Sdn Bhd.

Th T for, and should not be relied upon, by any third party.

No liability is undertaken to any third party.

is report is not intended Ground conditions are subject to continuing natural and man-made processes.

They can exhibit a variety of properties that vary from place to place, and can change with time.
Site investigation involves gathering and assimilating data by means such as inspection, drilling, excavation, probing, sampling and testing.

The collected data is only directly relevant to the ground at the place where and the time when the investigation was performed.

Any interpretation or recommendation given in this report shall be understood to be based on judgement and experience, not on greater knowledge of facts other than those reported.
If different ground or site conditions are encountered during construction activities or subsequent to the investigation performed for this report, either due to natural variability of subsurface conditions or previous construction activities, WorleyParsons should be notified of the differences and provided with an opportunity to review the recommendations contained in this report.
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REFERENCES WorleyParsons report 13229-PM-RP-001, Lynas Rare Earth Lanthanide Project, Preliminary Comparison of Tailings and By-Product Disposal Options, 14 February 2007.
T&T Konsult SDN BHD, Geotechnical Investigation Report for Petronas Centralised Utility Facilities (CUF) in Gebeng, Kuantan, February 1998.
MMCE-Franky Consortium, Final Report for Additional Soil Investigation Works for Kuantan-Kerteh Railway Project Civil Works – Package 2, Volume 1, Engineering Borehole Logs, February 2001. r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Page 22 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG Figures and Drawings r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Figures 302/14205 : Rev 2 : 10-Jan-08 LYNAS MALAYSIA SDN BHD LYNAS ADVANCED MATERIALS PROJECT CONCEPTUAL DESIGN FOR RESIDUE STORAGE FACILITY - GEBENG Figure 1 Approximate Location of Proposed Gebeng Site r:\4219298\project integration\02_del_komex\080116 conceptual design report for rsf gebeng (r0d)\4219298-300-en-rp-101-0d conceptual design report for rsf gebeng 080116.doc Appendices 302/14205 : Rev 2 : 10-Jan-08