Quarry excavation design and safe working practices
Formerly SIM 03/2005/11 - Face heights and safe working practices in rock quarries under the falls from height priority programme
This replaces SIM 03/2005/11. It outlines how quarries inspectors should approach applying and enforcing legal requirements relating to quarry face design and preventing falls of people or materials from quarry faces.
There is potential for a major incident, such as the collapse of a quarry face or a person or vehicle falling if the quarry face design and stability are inadequate, or if the measures in place to prevent such falls are insufficient.
This guidance covers checking the:
- quarry-face design meets expected standards;
- actual method of working is as set out in the design, the health and safety document and other documents;
- measures in place to prevent falls.
It also outlines the enforcement expectations if these checks identify significant shortcomings.
Inspectors should check:
- a suitable quarry face design is in place (see Appendix 1) that:
- addresses the types of failure which are likely to occur;
- quarry personnel know the parts of the design relevant to their work; and
- the actual method of working is as set out in the design.
- the health and safety document, tips and excavations rules and control measures address the following:
- the equipment being used has been assessed for its suitability, and is correctly sized to the face heights it will be working, so that maintenance can be carried out on both working and long term faces by mechanical methods;
- rock traps (where necessary to allow any falling rocks to be stopped at the foot of a face without falling / bouncing into a working area), and crest stand offs (i.e. a safe distance back from the face edge to allow for potentially unstable crest conditions) are stipulated as part of the design;
- the people in the management structure, on and off site, are competent for the role and decisions that each has to take.
- personnel working the face are not being put at risk from faces that are poorly managed or maintained;
- suitable control measures are in place to protect people and vehicles from falling from faces (edge protection, safe working practices for drilling and charging in rock quarries, etc);
- suitable excavation and tips rules are in place and that are regularly reviewed by the management and safety committee or employees’ representatives.
Where there are significant shortcomings in complying with the above then enforcement action should be taken to secure compliance (see Appendix 2).
The Quarries Regulations 1999 (QR) require quarry tips and excavations to be designed, constructed, operated and maintained so that they are safe and that instability or movement likely to give rise to a risk to the health and safety of any person (whether working in the quarry or not) is avoided (QR reg 30),. The quarry design should incorporate the quarry layout, extraction methods and operating procedures. This should include the required procedures to ensure the safety of all people within or around the site, including the methods that will be used to stabilise slopes, protect against rockfall, and to prevent the risk of falls of persons. In addition, quarry faces that form a significant hazard, as defined in the Regulations, are required to have a detailed 'geotechnical assessment' (QR reg 32 and ACOP L18).
The safety of excavated slopes is a requirement throughout the life of the quarry, and extends, so far as is reasonably practicable, to leaving the quarry faces in a safe condition when the quarry closes or ceases work (QR reg 6(4)). Failure to do so can lead to ground movements that can have an impact on the health and safety of those within and outside the quarry.
Regulation 9 of QR requires quarry operators to ensure that no-one undertakes any work at the quarry unless they are competent or they carry out work under the supervision of someone else who is competent to do both the work and provide the necessary training. (See OG on Competence of those working in the Quarry Industry for more information).
The Work at Height Regulations 2005 (WAH) are also relevant to safe quarry design and operation, and provide legal requirements to prevent the risk of falls of persons, vehicles and materials being thrown or tipped (WAH reg 10(3)) from quarry faces. This is relevant to various unsafe quarry operating practices such as end tipping. Regulation 10(4) on storage of materials is relevant to the stability of stockpiles. Regulation 11 on Danger Areas is also relevant.
No special visits or other organisational requirements are involved.
- Health and safety at quarries. Quarries Regulations 1999. Approved Code of Practice L118, ISBN 9780717663354; HSE Books.
- QNJAC Geotechnics, Face & Stockpile Operations Information Sheet 1, Guidance on Safe Face Management Operations in Quarries
- Rock Slope Engineering Hoek and Bray, 1974;
- The Stability and Hydrogeology of Quarries, Department for the Environment 1998.
Construction Division Operations 5 – National Quarries Inspection Team
Appendix 1: Typical quarry face design
The following indicates the minimum expected from a competent quarry design. It includes elements relevant to both rock quarries and sand and gravel type quarries:
- an overall assessment of the geological features of the deposit, with particular reference to:
- the strength of the rock mass,
- its relevant history,
- external influences, and
- structural orientation of the geological surfaces that will affect the quarry;
- designed orientation of the quarry faces to optimise stability for blasting and excavation, including failure modes and how they will be managed;
- the bench elevation, chosen to minimise the production of large rocks at the highest face elevations;
- the excavation method, selection of suitable equipment, and how this minimises risk to the quarry personnel;
- an assessment of the suitability of the design for short and long-term stability and maintenance of the faces;
- an indication of the probability of failure or the factor of safety of the overall excavation;
- competencies, duties and authority of those involved in the design of the quarry and how they fit into the management structure;
- competencies, duties and authority of those involved in coordinating geotechnical matters and production methods to ensure the safety of people at or affected by the quarry workings;
- how the blast design is changed to take account of face orientation and the requirement to produce safe faces; this may include:
- changing blast ratios,
- hole diameters, or
- using specialist blasting techniques;
- the inspection and remediation scheme including the competencies of those involved in identifying and implementing problems and remedial measures;
- what must be done before the quarry ceases operations or is abandoned to ensure that it is left, so far as is reasonably practicable, in a safe condition.
- The tip and excavation rules should:
- convey to all personnel the relevant design issues which affect their working methods,
- be regularly reviewed and
- be monitored and audited for their effective implementation;
- In addition to the geotechnical issues, the design must also allow adequate space for haul roads with provision for safety features as necessary, i.e.
- suitable road widths, with
- inner rock trap and berm,
- outer edge protection and
- face edge stand-off.
Appendix 2: Enforcement
Compliance with the provisions outlined in Appendix 1 is classed as “Compliance and administrative arrangements” under the Enforcement Management Model (EMM table 4).
Absence of, or inadequate, compliance with a defined standard (EMM table 3) (e.g. no or inadequate quarry face design) gives an initial expectation of an Improvement or Prohibition Notice. Unless local factors affect this expectation, a notice appropriate to the breach should be issued.
Enforcement should be considered where:
- the design is not adequate;
- there is evidence that the design is not being followed;
- the excavation rules are inadequate;
- the control measures are not being coordinated;
- the competence of the individuals and operator are not suitable for the risks at the quarry;
- the excavation method is not suitable for the excavation;
- equipment is not matched to the face heights and excavation methods;
- provision has not been made, through the design and operating practices, to ensure that when the quarry ceases operations or is abandoned it is left, so far as is reasonably practicable, in a safe condition;
- edge protection and other measures to prevent the fall of persons or vehicles are inadequate or otherwise ineffective.
Inspectors should consider prosecution for repeated failure of compliance.