General & Technical Method Including
The Thermal Dynamics Plan

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Revision history

Approval

This methodology is submitted for the approval of the SBR Representative in accordance with SOW Section 4.1 and Section 4.6, prior to mobilisation to Site.

Contents

1Introduction

This document describes how DTL (WA) Pty Ltd (DTL, the Contractor) will execute the field piping installation for the Bitterns Recycling Project at Shark Bay Resources' Useless Loop solar salt operation.

It is submitted to the SBR Representative under SOW Section 4.6 as the methodology component of the Project Execution Plan, and incorporates the detailed plan for managing the thermal dynamics of the pipeline required by SOW Section 4.1. It is issued for approval prior to mobilisation to Site.

1.1 Purpose

The document is prepared so that:

• the works are understood, and sufficient labour, plant and materials are planned to deliver the scope safely and to programme;
• project roles and responsibilities are defined;
• the works are executed in accordance with the Contract, the SOW, SBR's specifications and the applicable standards;
• SBR and DTL personnel responsible for coordination share a single, agreed method; and
• the thermal behaviour of a 20.7km surface-laid HDPE pipeline is engineered, not assumed.

1.2 Scope of this document

This methodology covers the installation of pipeline 560-BR-301-P1 from the F7 bitterns pump station to pond PM1, and the seawater flush supply pipeline 355-SW-302-P1, between the battery limits stated in Section 4. It excludes the items listed at SOW Section 5, which remain outside DTL's scope.

2Reference documents

3Definitions and acronyms

4Project description and battery limits

SBR operates a 7,000 hectare solar salt field at Useless Loop on Heirisson Prong, approximately 900km north of Perth. Bitterns — the concentrated brine remaining after the majority of the NaCl has precipitated in the crystalliser ponds — is currently collected in the F5 and F7 ponds, where it infiltrates the aquifer below the pond basement. To reduce reliance on that seepage process and recover the remaining NaCl, the bitterns will be pumped from F7 to the first pond in the evaporative process (PM1) and recycled.

4.1 The works

4.2 Battery limits

The battery limits of this scope are the first flange connection after the bitterns pump station (15-PP-102 pump discharge flange) and the discharge flange into the PM1 pond. Piping at the new pump location and outside these limits is excluded (SOW Section 5).

4.3 Principal-supplied materials

The following are free issued by SBR (SOW Section 6). DTL offloads, receives, inspects, records and stores these materials, and reports any transit damage or shortfall to the SBR Representative on receipt.

5Site conditions

The ambient conditions below are taken from SOW Section 8 (Bureau of Meteorology averages for Denham) and form the environmental basis of this methodology, including the thermal design at Section 11.

DTL is responsible for ensuring plant and components supplied are suitable for these conditions, and allows for all weather throughout the Contract period.

6Organisation and responsibilities

DTL is fully self-sufficient for the construction period. SBR plant (Franna, telehandler, EWP, forklift) and facilities (crib rooms, offices, ablutions) are not relied upon (SOW Section 4.3).

All personnel complete the SBR site induction before commencing work and meet the pre-mobilisation requirements at SOW Section 7.5, including pre-employment medicals, drug and alcohol screening, police clearance and a current tickets and qualifications matrix.

7Sequence of works

1. Pre-mobilisation — Project Execution Plan approved, including this methodology and the thermal design at Section 11. Bank guarantees lodged, insurances current, statutory declaration provided, risk assessment and traffic management plan issued.
2. Mobilisation and site establishment — personnel, plant, fuel pod, facilities and laydown established at the locations nominated from the KMZ review. SBR inspection of DTL plant before use.
3. Survey set-out — route, chainages, crossings, drain points, instrument locations and tie-ins set out and preserved against the supplied drawings.
4. Materials receipt — free-issued pipe and fittings offloaded, inspected, recorded, stored.
5. Stringing and jointing — pipe strung along the prepared benches and butt fused into strings.
6. Underground crossings 2–10 — excavation, sleeving where nominated, laying, backfill and compaction. Timed to suit SBR operations and approved by the SBR Representative.
7. Section 2 — Upper/Lower Bar crossing — executed within the SBR HV shutdown window. Power to the townsite is isolated; SBR coordinates haul road traffic control.
8. Above-ground lay, snaking and restraint — strings laid to the corridor with the thermal snaking regime at Section 11, earth pinned at 150m centres.
9. Tie-ins and appurtenances — ARVs, vacuum breakers, drain points, flow meters and the DN350 actuated valve.
10. Seawater flush line — 355-SW-302-P1 teed and installed.
11. Thermal relaxation and final tie-in — pipeline stabilised before closure welds, within the approved temperature window (Section 11.5).
12. Testing and inspection — to the approved ITPs and 00-SPE-Q-001.
13. Restoration and demobilisation — areas returned to their previous state to SBR's satisfaction.
14. MDR — submitted within two weeks of Completion.

8Mobilisation and site establishment

DTL is responsible for all mobilisation and demobilisation, including transport of personnel, materials and equipment, all transport and other permits, site access for personnel and deliveries, and suitable notice to the SBR Representative before mobilising and demobilising (SOW Section 4.3).

8.1 Laydown and access

The KMZ file 23092-KMZ-001rB has been reviewed to understand access, laydown and turnaround constraints across the full pipeline length. Laydown and facility locations nominated from that review will be confirmed with the SBR Representative before mobilisation. Establishment includes:

• offload of DTL plant and supply materials;
• arranging SBR inspection of DTL plant, to SBR requirements, before any use on Site;
• upkeep of work areas and any SBR-supplied facilities to SBR's satisfaction;
• signage, barricades and delineation to identify DTL work areas and protect personnel working near or entering them.

8.2 Self-sufficiency and refuelling

DTL will be fully self-sufficient: site office, crib, ablutions, stores, light vehicles and all construction plant. A fuel pod will be mobilised for remote refuelling of diesel plant, vehicles and gensets. Diesel is free issued by SBR and the pod refilled at the SBR workshop fuel tank, on the basis of SBR refuelling the pod once every two days. Refuelling is governed by the Hydrocarbon Controls Procedure (Section 18).

8.3 Survey set-out

DTL will carry out and preserve all survey set-out against the supplied drawings, and is responsible for construction being in the correct positions and to the correct levels. Set-out covers the route centreline and chainages, crossings 2–10, drain points at chainages 2810 and 8060, instrument locations at chainages 8030, 13886 and 20200, and all tie-in points.

9Materials handling, storage and stringing

All pipe is free issued in 21m lengths and is co-extruded white. Handling protects both the pressure wall and the white outer skin — the skin limits solar gain and is integral to the thermal behaviour assumed at Section 11.

10Jointing — butt fusion

Jointing is by butt fusion in accordance with AS/NZS 4130, PIPA POP003 and SBR specification 00-SPE-P-010, to a qualified welding procedure specification approved before production welding begins.

10.1 Method

1. Machine and operator — hydraulic butt fusion machine sized for DN560, calibrated, with a data logger. Only operators qualified for the machine and pipe class weld. Qualifications are held on Site and included in the MDR.
2. Preparation — ends cleaned, clamped, aligned and faced to a continuous ribbon. Alignment and ovality checked; toe-in corrected before fusion. Faced surfaces are not touched by hand.
3. Protection — welding is carried out under a shelter to shield the joint from wind, dust, salt spray and direct sun, and to keep the heat soak even. Welding does not proceed in rain or when wind prevents a stable heat plate temperature.
4. Fusion — heat plate temperature, bead-up, soak, changeover, fusion and cooling pressures and times to the WPS. Joints are not disturbed until cooling is complete under pressure.
5. Inspection — every joint visually inspected against the WPS acceptance criteria. Bead symmetry, uniformity and mismatch recorded. Debeading of butt welds is excluded (SOW Section 5).
6. Traceability — every joint receives a unique number, marked on the pipe and recorded in the weld register against operator, machine, date, time, ambient temperature, pipe heat numbers and the data logger record. Weld mapping gives complete traceability from the MDR back to the joint on the ground.

10.2 Flanged and mechanical connections

• All flange backing rings and bolt sets are 316 stainless steel.
• Stainless flanges are not electrically connected to carbon steel. Isolating sleeves and washers are fitted at every location where stainless bolts interface with the cast iron body of a valve or instrument.
• All gaskets are 3mm EPDM rubber, with the gasket ID matching the pipe ID.
• All bends are sweep type. Non-standard angles are fabricated from segmented elbows to the same radius as standard sweep bends.
• Electro-fusion branch (welded T) saddles are not used for any offtake for drains, air release valves or vacuum breaker valves. No mechanical, bolted or strapped tapping saddles are used for offtakes. Offtakes are fabricated items.
• Bolts are tensioned in a controlled cross pattern to the specified torque, recorded on the ITP.

11Thermal dynamics management

11.1 The problem

HDPE has a coefficient of linear thermal expansion roughly fifteen times that of steel. A 20.7km surface-laid DN560 pipeline at Useless Loop is exposed to a recorded ambient range of 5.5 °C to 47.0 °C. Left unmanaged, the resulting movement would either displace the pipeline out of its corridor, load adjacent infrastructure, or concentrate stress at the buried-to-surface transitions and at the tie-ins.

The design therefore does not attempt to prevent thermal movement. It accommodates movement along the free-laid lengths and restrains it only where the pipeline must not move.

11.2 Design basis

The white co-extruded outer skin is not cosmetic. It materially reduces solar absorption and so caps the peak wall temperature above ambient. The skin is protected throughout handling and installation (Section 9) because the thermal case assumed here depends on it.

11.3 Free thermal movement

Approximately 594mm of expansion and 526mm of contraction must be accommodated within every 150m of above-ground pipeline. This is the governing number for the method that follows.

11.4 Restrained thrust — why the pipeline is not simply pinned down

If a length were fully restrained against the expansion case, the end thrust would be:

Restraining the line against that thrust across 20.7km is neither practical nor desirable. The method below instead lets the pipe move where movement is harmless, and anchors it only at the points where it must not.

11.5 The method

(a) Controlled snaking of above-ground lengths

Above-ground pipe is laid in a deliberate serpentine within the prepared corridor rather than straight. The snake absorbs axial movement as small lateral deflection, so the pipe breathes along its own length instead of pushing at its ends.

A snake of approximately 601mm amplitude on a 30m wavelength accommodates the full expansion case within the corridor. Amplitude is set so the pipeline stays within its corridor at all times and, on sections 10 and 12, so the 4.5m access width to the edge of the pipeline is maintained at the snake's widest point — the amplitude is measured from the corridor edge inward, not from the centreline outward.

(b) Restraint regime

(c) Installation temperature control

• Jointing and laying are scheduled to the cooler parts of the day wherever practicable — the mean daily minimum is 17.8 °C and the mean daily maximum 26.8 °C.
• Ambient temperature is recorded against every joint in the weld register (Section 10.1).
• Pipe strings are not tied in immediately after fusion. Each string is left to reach ambient so the line is at a known, stable temperature when it is closed.

(d) Relaxation before final tie-in

• Strings are laid and left to relax to ambient before final closure welds are made.
• Final tie-ins are made within the approved reference window around 25 °C. Where a tie-in must be made outside that window, the offset is calculated and the snake set accordingly, and the variance is recorded and offered to the SBR Representative.
• Closure welds at anchors and instruments are made last, once the adjacent free lengths have stabilised.

11.6 Verification and hold points

12Above-ground installation and restraint

The majority of the route runs above ground on benches and clearings prepared by others along existing access roads and flow channels. DTL lays the strung and fused pipe into the prepared corridor to the snaking regime at Section 11.5.

• Pipe is laid on the nominated side of the corridor — for sections 3, 5, 6 and 8, on the west or south side of the existing Washery Waste line as detailed in Appendix A.
• The line is earth pinned every 150m where it runs above ground and is not constrained by an air release valve or an underground crossing within 500m. Approximately 2m is allowed per earth pin.
• Bearing surfaces are free of rock and sharp material that would point-load the pipe under thermal cycling.
• On sections 10 and 12 a 4.5m access width to the edge of the pipeline is maintained at all times. This governs the snake amplitude, and is surveyed and recorded (hold point T3).
• Section 13 runs downhill and cross country to the PM1 discharge. Restraint here accounts for thermal movement acting together with gravity on the grade.

13Underground road crossings

DTL constructs crossings 2–10, including all excavation, backfill and compaction. Crossing 1 (Upper and Lower Bar Road) is coordinated and completed by SBR. All underground crossings are direct buried pipe other than crossings 1 and 2, which are sleeved.

13.1 Method

1. Locate and prove existing services. Ground disturbance permit and SBR authorisation obtained before breaking ground.
2. Traffic management established to the approved plan (Section 19) before the road is opened.
3. Excavate to the required depth for approximately 1m of cover, batter or shore to the approved excavation controls, and keep spoil clear of the edge.
4. Prepare bedding, lower in the pre-fused string or sleeve, and confirm position and level against the set-out.
5. Backfill in controlled layers and compact to 00-SPE-C-002, restoring the road to at least its previous condition.
6. Survey and record the as-laid crossing for the MDR.

13.2 Section 2 — Upper/Lower Bar crossing

Section 2 is the critical interface of the works. SBR trenches and backfills for the sleeved bitterns recycling pipe and the seawater flush line. The pipeline installation must align with the SBR HV shutdown, during which power to the townsite is isolated, and SBR coordinates haul road traffic control. DTL will:

• pre-fabricate and pre-test the crossing string off the critical path, so that only placement and tie-in occur inside the shutdown window;
• agree the window, the sequence and the hand-back criteria with the SBR Representative in advance;
• resource the activity to complete within the window, with the crew and plant committed to it and no competing activity; and
• hold a documented contingency and back-out position should the window be curtailed.

14Tie-ins, valves, drains and instruments

15Testing and inspection

All testing is to the relevant regulations, standards, codes, drawings and SBR technical specifications. Where a conflict exists between these documents, DTL will seek clarification from the SBR Representative rather than proceed on an assumption.

• ITPs — suitably detailed Inspection and Test Plans submitted for SBR approval in accordance with 00-SPE-Q-001 before the associated work starts. Hold and witness points, including the thermal points T1–T6 at Section 11.6, are nominated in the ITPs.
• Calibration — all testing equipment calibrated by a NATA accredited authority, with certificates current and held on Site.
• Pressure testing — to the approved ITP and 00-SPE-P-010. HDPE test procedures allow for the visco-elastic behaviour of the material; test pressures are temperature corrected and the ambient temperature recorded throughout the test.
• Alternatives — DTL will not follow any alternative testing method or standard unless approved in writing by the SBR Representative.

16Quality and manufacturer's data report

DTL compiles a Manufacturer's Data Report for the works in accordance with 00-SPE-Q-001 during the works, for submission to SBR within two weeks of Completion. The MDR includes, at a minimum:

• manufacturers' certificates of conformity;
• AS/NZS 4130 compliance certificates for all HDPE pipework;
• HDPE pipe and fitting material traceability records;
• factory inspection and test records;
• product datasheets for all supplied pipework, fittings and associated components;
• pressure rating certification for all HDPE pipework and fittings;
• installation, handling and storage recommendations;
• welding and jointing procedures; and
• weld registers and weld mapping for complete traceability.

Records are compiled progressively rather than reconstructed at the end, so that traceability is continuous and the MDR is deliverable within the two-week window.

17Environment, health and safety

DTL's EH&S Management System specific to this project is submitted as part of the Project Execution Plan (SOW Section 4.6) and includes the Hydrocarbon Controls Procedure and an Emergency Management Procedure.

18Environmental management

• Hydrocarbon control — refuelling from the fuel pod under the Hydrocarbon Controls Procedure, with spill kits at the pod and at each plant location, drip trays under static plant, and bunding where required. Any spill is contained, reported to SBR and remediated.
• Contamination — the site contamination requirements at SOW Section 7.8 are applied. Any pre-existing or suspected contamination encountered is stopped on and reported to the SBR Representative rather than disturbed.
• Waste — a waste and rubbish management regime for offcuts, packaging, banding and general waste. Waste is segregated, contained against wind, and removed from Site. Nothing is buried or burned.
• The salt field — the works run along and across active pond levees and flow channels. Materials, waste and hydrocarbons are kept out of the ponds and channels at all times.

19Traffic management

A traffic management plan for the works is issued with the Project Execution Plan (SOW Section 4.6).

• The route follows and crosses live SBR haul roads and access tracks. Interaction between DTL plant, SBR haul traffic and light vehicles is the principal traffic risk.
• Road crossings are opened only under approved traffic management and only at times approved by the SBR Representative.
• At the Upper/Lower Bar crossing, SBR coordinates haul road traffic control as part of the HV shutdown.
• The 4.5m access width on sections 10 and 12 is maintained for SBR access throughout the works, not only on completion.
• Deliveries of 21m pipe lengths are scheduled and escorted to suit the access, laydown and turnaround constraints identified from the KMZ review.

20Site restoration and demobilisation

On Completion of the works, and once demobilisation has been approved by SBR, DTL returns all areas used to their previous state. At a minimum, areas are left as they were found, with all rubbish, redundant materials and the like cleaned up and removed, to SBR's satisfaction.

• Laydown areas, facilities, fuel pod and plant removed.
• Road crossings reinstated and compacted to 00-SPE-C-002.
• Ground disturbed by construction restored.
• As-laid survey and records issued; MDR submitted within two weeks of Completion.
• DTL will re-mobilise to Site should defects or faults be identified during SBR's commissioning (SOW Section 5).

AAppendix A — Pipeline section schedule

Pipeline 560-BR-301-P1, F7 bitterns pump station to pond PM1, per SOW Table 1. The supplied drawings govern; this schedule is the construction sequence reference.

Battery limits — the first flange connection after the bitterns pump station (15-PP-102 discharge flange) to the discharge flange into the PM1 pond.

BAppendix B — Thermal design basis summary

A one-page summary of Section 11 for site use. The full basis, method and hold points are at Section 11.

Site rules

1. Record ambient temperature against every joint.
2. Joint and lay in the cooler part of the day wherever practicable.
3. Let strings relax to ambient before final closure welds.
4. Tie in within the approved window around 25 °C. Outside it, calculate the offset, set the snake accordingly, record it and offer it to the SBR Representative.
5. Never let thermal thrust reach a flange, an instrument or the pump station.
6. Check the corridor and the 4.5 m access at the snake's widest point, not its centreline.

Hold points