Cover Story – Working Safely with Geo Technical Risk in Quarries

DR ELIZABETH GIBSON, General Manager of the CMPA provides a brief outline of CMPA’s latest guideline.

The CMPA held a workshop in February 2015 on “Safe Working Distances from Quarry Faces”. Out of that Workshop we are pleased to outline the contents here of the Guideline “Working Safely with Geo Technical Risk in Quarries” which should be published in November 2015.

This Guideline Working Safely with Geo Technical Risk in Quarries together with the CMPA’s Work Safely Reference Manual aims to support CMPA members in meeting the requirements of the Victorian Occupational Health and Safety Act 2004 by ensuring that:

• Geo-technical hazards associated with quarry ground movement and quarry operations are identified, assessed where required and then controlled in a manner to reduce the risk of personal or vehicle engulfment as far as is reasonably practicable; and,

• Quarry infrastructure is established in a manner so as to prevent vehicles that have lost control, or persons working close to edges from falling to another level.

To achieve the above this Guideline focusses on Pit Design and Water Management, the two most critical elements of winning source materials in a safe and economical manner.

Geotechnical risks at a quarry are defined by the Department of Economic Development, Jobs, Transport and Resources (DEDJTR) – Earth Resources Regulation Branch (ERRB), as those risks associated with ground movements. Ground movements are typically limited to the area of the quarry and to a region around the quarry. Ground movements may be significant (such as subsidence or natural rebound) or catastrophic (such as batter collapse). Irrespective of the type of ground movements, it is possible for persons, infrastructure or the environment to be harmed. It is essential that the risks of harm arising from ground movements are minimised during the period of operation of the site, rehabilitation and post-closure.

Quarry workers can potentially be at risk when working on, in or the vicinity of:

• Excavated Embankments inclusive of hard rock quarry faces developed by drilling and blasting and mechanically excavated hard rock, sand or clay pits developed by excavators, dozers, scrapers, front end loaders, hydraulic sluicing and dredging;

• Constructed Embankments inclusive of dam walls, overburden dumps, bunds, stockpiles, slimes or settlement ponds, backfilled ramps and rehabilitated pit faces;

• Natural Embankments inclusive of steep natural slopes. The potential risk associated with working on, in or within the vicinity of an embankment is as follows:

• A person, vehicle or mobile equipment falling from the embankment to a surface below or into a Water Containment Structure, i.e. dams or silt settlements ponds;

• A person, vehicle or mobile equipment being struck from material falling from the embankment;

• A person, vehicle or mobile equipment being engulfed by materials from sliding, collapsing or subsiding embankments;

• A person, vehicle or mobile equipment being inundated with water or silt slurry from a failed embankment of a Water Containment Structure.

Rather than go into further detail the Table of Contents is listed below

TABLE OF CONTENTS

1. Introduction
   

   Photos of Embankments

2. Relevant Regulation and Resource Materials
3. Geo Technical Risk Overview
4. Geotechnical Risk – Excavated Embankments: Weak Geological Materials; Strike and Dip; Unstable Geological Structures; Excavation Design; Excavation Techniques; Blast Vibration, Seismic Events; Changed Surface and Groundwater Conditions
5. Geotechnical Risk – Constructed Embankments: Embankment Design; Construction Techniques; Excavating close to Constructed Embankments; Blast Vibration, Seismic Events; Changed Surface and Groundwater Conditions
6. Geotechnical Risk – Natural Embankments:
7. Slope Stability Assessment: Geotechnical Considerations; Hydro-Geological Considerations; Environmental Considerations
8. Inspection and Monitoring of Embankments: Inspection and Warning Signs; Monitoring Systems
9. Overview of Controls to Reduce Risk
10. Surface and Groundwater Management
11. Edge and Falling Rock Protection Berms: Edge Protection Berms – Mobile Plant or Light Vehicles;  Edge Protection Berms – Pedestrians Only; Falling Rock Protection Berms
12. Haul Roads: Road Width; One way traffic, straights and corners; Two way traffic; Grades and Crossfall
13. Drilling and Blasting
14. Stockpiles: Angle of Repose; Bumper Dump Stockpiling; Direct Dump Stockpiling; Laminated  Stockpiling; Conical Stockpiling; Surgepile Stockpiling; Stockpile Structures; General Stockpile Safe Work Practices; Dump or Laminated Stockpiles Safe Work Practices; Surgepiles Safe Work Practices; Sampling materials from a stockpile
15. Faces: Identifying Potential Rockfall; Controlling Rockfall; Safe Work Practices on Benches
16. Water Containment Structures: Wall Stability; Berms and Fencing; Overflows; Dewatering Channels;  Working alongside Water Containment Structures; Cleaning out Settlement Ponds; Signage
17. Overburden
18. Rehabilitation
19. Management of Change

It is intended that this CMPA Guideline “Working Safely with Geo Technical Risk in Quarries” together with the CMPA Guidelines “Traffic Management in the Construction Materials Industry” and “Blast Management Plan Template in the Construction Materials Industry” will assist Members in their businesses and when applying for Work Plans/Work Plan variations.

 

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