Location: Mesa J near Pannawonica, WA
Client: Rio Tinto
Duration: May 2022 – December 2023, July 2022 – May 2024, November 2022 – June 2024
Our largest operation to date with continuous projects and their scope variations awarded. 2.5 million tonnes of mined out tailings was stockpiled in Pit 7 that can contribute to SOP. Out of 2.8 million cubic metres moved and 31.4km of pipeworks installed, 755,000 cubic metres was borrowed from the basin of the TSF8 Stage 1 (East Cell), adding extra tailings storage capacity. Tailings was being deposited into TSF4 whilst dry tailings were being mined out, an experience the team has from Mesa J TSF3 Stage 2. Overall, the projects were very dynamic.
TSF4 Mining Tailings & Civil Works and Recommissioning Tailings Pipeline:
- Establishing access ramp and track on dry tailings;
- Undertake test pitting to see the extent of coarse tailings;
- Mining out tailings, approximately 1 million m3;
- Foundation preparation;
- Constructing cross-walls out of conditioned mine waste, and excavating trenches, to control tailings deposition, the tailings beach profile, and the supernatant pond;
- Constructing a new decant causeway;
- Trimming the cross-walls, decant and their batters;
- Install guideposts and delineators;
- Grading the crest of the TSF;
- Installing 6no. Vibrating Wire Piezometers (VWP’s) and connect them to existing data loggers;
- Relocate existing DN400 HDPE-lined steel pipe flanged Table H, DN400 PU-lined steel pipe flanged Table H, DN400 mining hose flanged Table H, OD355 (DN350) SDR11 PN16 PE100 HDPE pipe flanged Table E, 11no. pneumatic-actuated spigot valve assemblies on skids reconfigured to suit, from across Mesa J Mine at TSF3 and TSF5, and install at TSF4, totalling 3.8km;
- Uninstalled 1km of installed pipeworks and reinstall to achieve continuous tailings deposition, including disconnecting, relocating and reconnecting spigots, extending spigots, shortening spigots, slotting spigots, repairing burst pipelines.
- Polyweld OD400 (DN400) SDR7.4 PN25 PE100 HDPE pipe flanged ANSI300, OD400 (DN400) SDR7.4 PN25 PE100 HDPE pipe flanged Table E, OD355 (DN350) SDR11 PN16 PE100 HDPE pipe flanged Table E;
- Reseal knifegate valves on spigot valve assemblies, both high pressure and low pressure;
- Supply and install burst disc assemblies;
- Supply additional burst discs;
- Civil works to accommodate the pipeworks with improved accesses including pipe crossings, and improved windrows.
TSF8 Early Works:
- Construct a buttress against TSF4 out of mine waste;
- Relocate a topsoil stockpile;
- Undertake test pitting to sample a subsoil stockpile;
- Foundation preparation;
- Construct a haul road and access ramps out of conditioned mine waste and conditioned subsoil;
- Place and compact in 1m lifts;
- Trim batters;
- Widen and raise the haul road to TSF8 Stage 1’s Central Dividing Embankment;
- Widen and raise the eastern access ramp to TSF8 Stage 1 (East Cell) Decant Causeway;
- Procure long lead items for TSF8 Stage 1 (East Cell) including pneumatic-actuated and manual handwheel knifegate, butterfly, pinch and air valves, DN300 and DN250 PU-lined steel pipe and Victaulic couplers, DN300 and DN250 mining hose, DN300 and DN250 rubber-lined steel tees and spools, electric submersible pumps, Variable Speed Drives (VSD’s), generators, diesel fuel tanks, TruFlo pump, suction turrets, solar-powered telemetry skids, pressure transmitters, flow transmitters, level transmitters and turbidity transmitter.
TSF8 Stage 1 (East Cell):
- Foundation preparation;
- Construct embankments and access ramps out of conditioned mine waste and conditioned subsoil;
- Place and compact in 0.5m lifts;
- Trim subgrade and batters;
- Construct kilometres of windrows;
- Road pavement construction;
- Trim wearing course material;
- Install guideposts and delineators;
- Construct kilometres of pipeline corridors and access roads;
- Construct a dump pond and reshape an existing dump pond;
- Construct additional access ramps and pipeline crossings;
- Relocate dewatering pipelines;
- Find and polyweld and blank dewatering pipelines;
- Design changes introduced dewatering;
- Clear vegetation;
- Screen for coarse rockfill;
- Dump rockfill to form a stable foundation;
- Screen drainage material delivered by the Mine to produce approximately 10,000 m3 of screened drainage material;
- Construct a coffer bund;
- Install geotextile above the screened drainage material and in some cases, below the screened drainage material;
- Import ballast and backfill around OD710 (DN700) SDR9 PN20 PE100 HDPE slotted pipe sleeves flanged Table F;
- Import blue metal and spread for an electrical equipment pad;
- Widen and raise the Central Dividing Embankment Access Ramp;
- Excavate an emergency spillway and place rock protection on the batter;
- Place rock protection down the batter interfaces with waste dumps;
- Supply and install data loggers;
- Extend existing VWP cables to new data loggers;
- Procure more items for TSF8 Stage 1 (East Cell) including pneumatic-actuated and manual handwheel knifegate and air valves, OD400 (DN400) SDR7.4 PN25 PE100 HDPE pipe, OD400 (DN400) SDR13.6 PN12.5 PE100 HDPE pipe, OD315 (DN300) SDR7.4 PN25 PE100 HDPE pipe,OD315 (DN300) SDR13.6 PN12.5 PE100 HDPE pipe, OD250 (DN250) SDR13.6 PN12.5 PE100 HDPE pipe, OD200 (DN200) SDR17 PN10 PE100 HDPE pipe, OD160 (DN150) SDR 13.6 PN12.5 PE100 HDPE pipe, OD110 (DN100) SDR7.4 PN25 PE100 HDPE pipe, OD63 (DN50) SDR13.6 PN12.5 PE100 HDPE pipe, Table E backing rings, reducers, tees, sweep bends and elbows, gaskets, stud bolt sets, mining hose, pre-cast concrete pipe supports, headwalls and slabs, pneumatic switch posts with concrete footings, PU spacers, rubber-lined steel spools and lateral tees, electric actuators for butterfly valves, power cables, instrument cables, cable tray and lids.
- Polyweld and install kilometres of tailings pipeline – PU-lined steel, Rubber-lined steel, HDPE, and slotted spigots;
- Polyweld and install kilometres of decant return water pipeline;
- Polyweld and install kilometres of seepage water pipelines;
- Hydrostatic pressure test;
- Install 134no. valves;
- Install 2no. electric submersible pumps;
- Install 2no. VSD’s;
- Install 2no. generators and diesel fuel tanks;
- Install 2no. TruFlo pumps;
- Modify 1no. TruFlo pump;
- Install 16no pieces of instrumentation – pressure, flow, level, turbidity;
- Install 6no. solar-powered telemetry skids;
- Supply 4no. telemetry enclosures for existing TruFlo Pumps, one of which was installed on the new TruFlo pump;
- Construct pipeline road crossings with steel pipe wrapped in Denso and cement stabilised backfill;
- Supply and install lifebuoys and stands with concrete footings;
- Decommission existing steel pipeline;
- Swap out blocked DN250 PU-lined steel pipeline spools;
- Realign pipelines;
- Modify the Decant Causeway and ramps;
- Electrical installation and testing;
- Energise and commission.
