Mangoola Coal Mine, Muswellbrook, NSW Mangoola Coal Mine, Muswellbrook, NSW Mangoola Coal Mine, Muswellbrook, NSW Mangoola Coal Mine, Muswellbrook, NSW

Mangoola Coal Mine, Muswellbrook, NSW

Project featuring the VSoL Retained Earth™ Panel System

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General Information

Mangoola Coal is an open cut coal operation in the Wybong area, 20 kilometres west of Muswellbrook and approximately 10 kilometres north of the township of Denman, NSW. Mangoola Coal is based on a large, undeveloped coal reserve of approximately 150 million tonnes (Mt). Mangoola Coal aims to provide a long term, secure and profitable supply of high quality coal, whilst conducting operations in an environmentally responsible manner through the effective management, mitigation and offsetting of environmental impacts.

Robson Civil Projects were awarded the civil works package, which included the design & construction of a 20.95m high VSoL panel Retained Earth™ wall. VSL Australia was engaged for the design and supply of the proprietory Retained Earth™ system whilst Retaining Solutions were engaged for the works described herein.

The existing clay foundation had to be excavated approximately 4m in depth and replaced with a 2% stabilment treated compacted granular select fill material. Minimum strength parameters for this zone required by design were > 1MPa UCS and an undrained shear strength of 500kPa. Upon installation of base course row of panels and backfilling the first 2m of the VSoL wall, the base row timber props were removed in front of the wall enabling associated drilling and piling works to be carried out without delay while VSoL wall construction continued.

Retaining Solutions scope involved the following installation of:

  • Unreinforced concrete levelling pad;
  • VSoL reinforced concrete facing panels (1640m2 face); VSoL galvanised reinforcing mesh (lengths varying from 7m up to 16m), connecting pins and geotextile fabric to all vertical and horizontal panel joints;
  • Engineered Fall from height handrail system for both panel placement and wing wall batters;
  • RSW select backfill material (approx 30,000m3);

Mangoola Coal Mine, Muswellbrook, NSW


  • General backfill to rear of reinforced fill zone (approx 150,000m3). RCP installed the general backfill zone in conjunction with Retaining Solutions wall erection operations, utilising dozers, scrapers and up to ten 40tonne articulated dump trucks;
  • Vertical drainage in form of geotextile encapsulated gravel chimney drain to rear of reinforced fill zone (approx 2000m2);
  • 5% cement stabilized medium (approx 200m3) to underside of dump slab including level conformance to concrete blinding layer;
  • Supply/form/fix “fibre reinforced” concrete dump slab 40MPa (approx 200m3 - using Dramix fibres), including all cast rail sections and corner plates;
  • 50mm thick bedding sand layer; HDPE 2.5mm thick double textured membrane, including denso-tape sealant; geocomposite protection layer and associated mechanical fixing to the entire perimeter of the dump slab.

Retaining Solutions also worked closely with RCP to provide plant wet-hire (excavators and tracked bobcats) for the following works: RCP crushing operations onsite to win, load, process select & DGS materials; selectively winning & hammering raw feed for the crushing operations; detailed excavation works around CHPP area, including crane pads, footings & drainage; final trim of ROM batters, product stockpile pad batters & plant road batters including spreading of topsoil; detailed excavations of drainage channels around CHPP Plant Roads; rock hammer work for detailed excavation of toe of rock batter along reclaim tunnel, including chamber pads; bulk excavation of reclaim tunnel; finishing works around all CHPP Stage 1 & 2 works, including regrading, topsoil spreading and scarification of surfaces for preparation of revegatation.

This project proceeded trouble free with a close working relationship established between Robson Civil Projects, Retaining Solutions and XStrata Coal.

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Project Specs

  • Application - Dump Structure
  • Product - VSoL Retained Earth™ Panel System
  • Finish - Plain Grey Smooth
  • Area - 1640m2
  • Max. Height - 20.95m
  • Length - 115m
  • Loadings - CAT 793 Dump Truck (384t)
  • Design life - 30 years
  • Owner - XStrata Coal
  • Client - Robson Civil Projects (RCP)
  • Construction - 2 months

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