Blast Site Edge ProtectionInformation on the use of edge protection systems in the blasting area

Drilling and BlastingToolbox Talk : 03

Quarries Working towards a safe and healthy quarrying industryNationalJoint EmployersAdvisory EmployeesCommittee Health and Safety Executive

This publication may be freely reproduced except for advertising, endorsement or commercial purposes. The information is current at February 2009. Please acknowledge ‘QNJAC’ as the source 

Target AudienceAny person likely to be working in the blasting area and those supervising such operations.

Updated September 2009

Blast site edge protection1 : Introduction

• Lives have been lost in the past through falls from quarry faces.

• Thankfully this is now very rare mainly due to control measures introduced to prevent it.

• This toolbox talk is designed to help the industry to reduce further the likelihood of these incidents.

• In deciding what are the most suitable control measures for any particular circumstance, account needs to be taken of both The Quarries Regulations 1999 and the Work at Height Regulations 2005.

Blast site edge protection2 : Managing the Risk

• The Operator is responsible for Health and Safety on site including all drilling and blasting activities

– This includes the design, construction and provision of blast site edge protection

• Blast site activities include– Surveying, marking out, drilling, loading and firing

• It is therefore very important to carry out a site specific risk assessment including all the personnel likely to be involved in the blasting operation

– For Example • Driller, Shotfirer, Explosives Supervisor, Quarry Manager• Bulk explosive supplier, Geotechnical Consultant

Blast site edge protection2 : Managing the Risk

• The following topics should be considered as a minimum in a risk assessment

1. Prevention of personnel and equipment from falling over the edge

2. The site geology and stability of the face.3. Access to the blast site for drill rig, delivery of stemming,

explosives delivery vehicles, bulk explosive trucks and emergency vehicles.

4. Blast design parametersSuch as spacing, burden, etc

6. Profiling and surveying operations7. Weather conditions

Blast site edge protection 2 : Managing the Risk

• The Work at Height hierarchy should be followed in selecting the method used:-

– Collective measures should be given priority over personal protective measures. Physical barriers such as the safety bund and post and strap should be considered first

– Where the use of physical barriers creates an unacceptable risk then other measures such as delineation of the danger zone or harnesses should be considered

– The Quarry operator should be able to show that they have considered how a fall from an open edge will be prevented for that particular shot.

Blast site edge protection3 : Protection Methods

• Safety Bund– Advantages

• Provides protection for people• Does not need removing before blast

– Disadvantages• Can cover up bad edge conditions

– A safe system of work needs to be established detailing how such bunds put in place

• Requires the movement of mobile plant close to the crest

Blast site edge protection3 : Protection Methods

• Safety Bund– How high do the bunds need to be ?

– People only on the blast area• Not less than 1m• In this case a second bund will be

required behind the blast to preventvehicles from encroaching

– Vehicles operating on the blast area• A minimum of 1.5m or the radius

of the largest vehicle wheel

Blast site edge protection3 : Protection Methods (continued)

• Post and Strap– Designed to prevent personnel from accidentally approaching

the edge– Advantages

• Acts as a physical barrier to prevent personnel from falling over face– Disadvantages

• Barrier will not prevent machinery from falling over face• Requires a drill rig to approach the edge to drill post holes• Placing and removal of system requires personnel to approach the

edge– Normally this will require the use of an additional fall prevention system

• Removal of system can result in the initiation system being disturbed with the potential for misfires

Blast site edge protection3 : Protection Methods (continued)

• Post and Strap – Bad Practice

Only a single strap has been used

Worse than useless as the protection has been placed such that the face edge comes inside the protection!

!

Blast site edge protection3 : Protection Methods (continued)

• Post and Strap – Good Practice

Two straps have been used

Straps are tensioned

Line of protection is positionedjust in front of the first row of holes

Blast site edge protection3 : Protection Methods (continued)

• Stand-off Distance– In this case workers may not approach within a specified

distance to an unprotected edge– The distance needs to be well delineated with some form of

barrier• Good example is when used with cones and rope

– This system needs to be well supervised– Advantages

• No need for the drill rig to approach the bench edge• Can easily be removed before the blast

– Disadvantages• Does not prevent either people or equipment from falling over face

• Example of Stand-off Distance– In the photograph this system is used on a site that employs a

stand-off distance of 3m.

Blast site edge protection3 : Protection Methods (continued)

A cone and rope system has been used to indicate the stand-off distance fromthe edge of the face

Note also that in this case a bund has been positioned to prevent equipment such as bulk explosive trucks from coming on the blast area

Blast site edge protection3 : Protection Methods (continued)

• Fall Prevention Systems– Should only be used as a last resort– Should be installed so as to

prevent personnel reaching the crest and falling over the face

– Requires that personnel are also trained in emergency recovery procedures.

– Many sites require the use of suchsystem when removing the post andstrap system previously described

Blast Site Edge Protection4 : Key Points

• Edge protection is required for all blast areas

• Each blast should be separately assessed to determine suitable protection measures for that location

• A single edge protection system may not be universally appropriate

• If you think the edge protection is inadequate STOP WORK and inform your supervisor