Construction Health and Safety

EXPLOSIVES

Section 8C

8C - 1

CONTENTS

Introduction 8C–3

Preliminary survey 8C–3

Notifications 8C–3

Documentation 8C–3

Storage 8C–4

Transport 8C–4

Mixing on site 8C–5

Use of explosives 8C–5

Code of signals 8C–5

Shot firing 8C–5Competence of shot firers 8C–5General precautions 8C–5Electrical shot firing 8C–6Detonating cord 8C–6Shot firing using safety fuse 8C–6

Tunnelling and shaft sinking 8C–7

Scaling down faces 8C–7

Misfires 8C–7Electrical shot firing misfires 8C–7Safety fuse misfires 8C–7Records 8C–8

Disposal of explosives 8C–8

References 8C–9

8C - 2 December 2010

EXPLOSIVES

8C - 3December 2010

IntroductionThis subsection aims to give general guidance to Site

Managers on the acquisition, keeping, transfer, storage,transportation and use of explosives in the constructionindustry. In addition, it is anticipated that the information willenable Sub Contractor’s method statements and riskassessments to be assessed. Further guidance on the use ofexplosives is given in BS 5607:1998 "Code of Practice forsafe use of explosives in the construction industry", Section8A of this manual entitled Demolition and section 15 entitledQuarries associated with construction operations. Advice onthe explosives used in cartridge operated fixing tools isgiven in BS 4078 Part 1 (also see Section 13 of this manual– Portable Tools).

The legal framework underpinning this section is TheManufacture and Storage of Explosives Regulations 2005and The Control of Explosives Regulations 1991.

Explosives are used extensively in the quarrying industryand this section also draws on the Health and SafetyCommission’s Approved Code of Practice and Guidance, inthis respect.

AppointmentsBefore any work involving explosives is planned and

carried out the person responsible for the site, for examplethe Principal Contractor, must appoint someone withsufficient knowledge and experience to oversee this work.Even when a sub contractor will carry out the blasting theSupervisor appointed by the principal contractor must satisfyhimself or herself that the planning, documents andimplementation are satisfactory as this is obviously a high-risk operation. Similarly, the business actually carrying outthe work with explosives must ensure that Supervisors andShot firers are competent to carry out their work. Thecompetence and training of Shot firers is dealt with later inthe section. The training of both engineers and shot-firersinvolved in this work is detailed in the Code of Practice forthe Safe Use of Explosives in the Construction Industry. It isappropriate that engineers, directly connected with the workwith explosives, have at least the same training as shot-firers.

Risk AssessmentThe Management of Health and Safety at Work

Regulations 1999 requires that every Employer carries out arisk assessment of the work under his direct control. Wheremore than five persons are employed by the business theassessment must be written down. The risk assessment isbasically a planning process to ensure the safety ofemployees and other persons who could be affected by theworks. The assessment must be suitable and sufficient and itis vital that it is completed by persons who really haveadequate knowledge and experience to properlyunderstand and plan the work. The main risks associatedwith the use of explosives are an unplanned fire andexplosion, release of toxic fumes and flying particles.COSHH and manual handling concerns are lesser riskswhich need to also be considered. These and the hazardsand precautions associated with the work process will allform elements of the written assessment. Therefore, storage,transport, mixing of explosives, maintenance of machinery,guarding, etc must all be included along with“environmental issues such as vibration, noise, etc.

Preliminary surveyBefore any work involving the use of explosives is started,

a detailed survey should be made of the site and itsadjoining areas. BS 5930:1999 entitled;” Code of Practicefor Site Investigations” gives guidance on this matter. Whereearthworks, tunnelling or demolition are involved, relevantinformation may be obtained from British Standards 6031,

6164 and 6187 respectively.Special attention should be given to the character and

structure of the geographical strata to ensure that they arenot likely to transmit ground vibration to areas where it islikely to cause damage. The affect on utilities, includingunderground and over ground services, should be carefullyconsidered. The survey must include the taking ofphotographs particularly where there is already evidence ofmovement or damage.

NotificationsCertain local authorities have special powers of control

over the use of explosives, granted under Acts of Parliament.A check should be made to establish whether such powersexist in areas where explosives are to be used.

Prior notice of the intention to use explosives should begiven to all those who may be affected. For example, thewater; gas, electricity and telephone authorities, thehighways authority, Network Rail, the police, fire and rescueservice and airports, local residents (consultation only).

Under the Control of Pollution Act 1974 (see Section 34 –Environment), local authorities, are given the power toprotect the community at large against noise which amountsto a nuisance. Local authorities may specify their ownrequirements for limiting noise, but contractors are given theright to apply to local authorities for consent to carry outwork by a particular method, saying what steps theypropose taking to minimise noise. Complaints are likely tooccur were the noise created by blasting operations is morethan 10dBA greater than the background noise andtherefore knowing what the background noise level is at thereceptors from which complaints are likely to arise isimportant. Having this information will also informdiscussions with the Local Authority’s Environmental Healthpersonnel. BS 4142: 1997 entitled, “Rating industrial noiseaffecting mixed residential and industrial areas” providesadvice on the process.

DocumentationUnder the Control of Explosives Regulations 1991

(COER) as amended by the Manufacture and Storage ofExplosives Regulations 2005 (MSER) explosives may beacquired, or stored only by persons who hold a validExplosives Certificate issued by the police. This is usuallyreferred to as the "acquire and keep" certificate. AnExplosives Certificate may be issued for both acquisition andstorage of explosives or for acquisition only. Certificatespermitting acquisitions only should be obtained where it isintended to use explosives on the day they are delivered tosite. An Explosive Certificate is not required for theacquisition or storage of cartridge operated tool cartridgeswhich carry the following UN numbers: 0275, 0276, 0323or 0381.

In addition to the explosives certificate the personordering or taking delivery of explosives must have a"recipient competent authority" which can be obtained fromthe Explosives Section of the Health and Safety Executive, Tel0151 951 4025. Applying for one of these documentsinvolves the production of the Police explosives acquire andkeep certificate, first time applicants should include acovering letter explaining the situation as this speeds up theadministrative process. Renewals will require the productionof the old "RCA". Communication can be by post or fax, theExplosive Policy Section’s fax number is 0151 951 3891.The requirement to obtain a RCA comes from the “Placing onthe Market and Supervision of Transfers of ExplosivesRegulations 1993” (POMSTER).

NB Explosives cannot be purchased without thisdocumentation.

Application for licences (over 30Kg) and registration (for

30Kg or less) are made to the relevant licensing authority, inbroad terms these are:1. HSE for the manufacture and/or storage of more than

two tonnes or for the storage of less than two tonneswhere prescribed separation distances cannot be met.

2. The Police for storage up to two tonnes where any of theexplosives to be stored require an Explosives Certificate(mainly blasting explosives and gunpowder).

3. The local authority for storage of up to two tonnes ofother explosives (primarily fireworks).

Note: The local authority, in certain areas will be the Fireand Rescue Authority while in others it will be theCounty Council, District Council or London Borough. InScotland and Wales the local authority is the UnitaryAuthority.

StorageThe Manufacture and Storage of Explosives Regulations

2005 require the following:Anyone manufacturing or storing explosives must take

appropriate measures to prevent fire or explosion; to limitthe extent of any fire or explosion should one occur; andprotect persons in the event of a fire or explosion.

A separation distance must be maintained between theexplosives building and neighbouring inhabited buildings toensure that risks to those living or working in the area arekept to an acceptable level. Schedule 2 of MSER givesseparation distances depending upon the type of explosive,density of building, and the type of construction of the store.

With certain exceptions a license is required for thestorage of explosives. In most cases “stores” holding lessthan two tonnes of explosives are either licensed orregistered by the local authority or police. HSE license thelarger stores and any manufacturing facility.

HSE may not grant a license for manufacturing ofexplosives until the local authority has given its assent; thisnormally follows a public hearing.

There are explicit exemptions from licensing andregistration for temporary storage of up to 7Kg of explosivesfor 24 hours maximum but the persons involved will still berequired to comply with the regulations for prevention of fireand explosion, communication of fire/explosion and toprotect people from the effects of fire or explosion.

Guidance on the construction of storage facilities andrelevant safety matters are available from the licensingauthority; this includes the police, the local authority or,where a significant amount of explosives are stored,, theHealth and Safety Executive (Inspectorate of Explosives) Seethe Approved Code of Practice and Guidance LI 39 entitled,“Manufacture and Storage of Explosives Regulations 2005”.Advice may also be obtained from the manufacturer of theexplosives which are to be used. The storage facilities will beinspected and therefore it is important that the guidance andadvice is complied with.

Where it is not possible to achieve safe separationdistances, for example because of the tight confines of thesite and the location of the proposed store with adjoiningoccupied structures explosives may have to be delivered andused on the same day and in this way storage will beavoided.

Finally, it is worth noting that where a site has more thanone store it is the total amount stored on site that will beassessed for licensing and not the maximum amount storedin any one store.

The movement of explosives into and out of the store mustbe recorded, and there must be a formal procedure foraccepting delivery of explosives and for checking that theyconform to the contents of the advice note. It is essential toensure that detonators are stored separately from otherexplosives. Full details of the information to be recorded bypeople who acquire or store explosives is contained inSchedule 3 to the Control of Explosives Regulations 1991.

No person may transfer explosives to another person unlesshe is satisfied that the transferee has an Explosive Certificatecertifying him to be a fit person to acquire explosives. Thisdoes not prohibit employers from giving explosives to theiremployees, but it does mean that a Principal Contractor mustcheck that a Sub-contractor has an Explosives Certificatebefore providing the Sub-contractor with explosives.

Explosives stores must be kept clean and free from grit.Rubber Overshoes must be kept in each store and worn bypeople who are not wearing rubber soled footwear andhave to enter the store. No iron or steel implements shouldbe taken into explosives stores and no naked lights or othermeans of ignition should be taken within 25m of them.

The issuing of explosives should be restricted to personswho have been authorised in writing by the Site Manager.

Section 23 of the Explosives Act 1875 requires thatanyone storing explosives takes all reasonable precautionsto prevent unauthorised access to the explosives. The localpolice should be contacted on the security aspects of storingexplosives on site. It naturally follows that the loss or theft ofexplosives must be reported immediately to the police.

TransportThe transport of explosives on public roads is subject to

the Carriage of Explosives by Road Regulations 1996,which place various duties on operators of vehiclesincluding:1. the requirement for vehicles to be suitable, having

regard to the type of explosives (as defined in theClassification and Labelling of Explosives Regulations1983) and quantity of explosives carried; quantity limitsfor various types of explosives are also imposed,

2. restrictions on the carriage of loads of mixedexplosives,

3. the requirement for the marking of vehicles andcontainers, except where small quantities of certaintypes of explosives are carried,

4. the requirement for written, specified information aboutthe load to be kept on the vehicle,

5. the requirement to take all reasonable steps to ensuresafe and secure carriage,

Detailed guidance on quantities of explosives which maybe carried, the construction of vehicles and containers andthe documents involved is contained in HSE booklets L91and L92 (see References).

Subject to exclusions for certain groups and quantities ofexplosives, the Carriage of Dangerous Goods by Road(Driver Training) Regulations 1996 apply (see p1-42).Vehicle operators must ensure that drivers have receivedadequate instruction and training on dangers which mayarise, action to be taken in an emergency and on their dutiesunder HASAWA and the Carriage of Explosives by RoadRegulations. Drivers must attend an approved course, onsuccessful completion of which they will be awarded aVocational Training Certificate. Drivers must carry thesecertificates.

Finally, the Transport of Dangerous Goods (SafetyAdvisers) Regulations 1999 apply where explosives arecarried on the public roadway. These regulations, whichrequire the safe system of transport to be prepared by aperson with training and knowledge of the health and safetyimplications of carrying explosives, will normally bear downon the supplier who should be organised so that he deliversdirectly to the explosive store on the day when blasting istaking place.

Further transport of explosives on site must be in a vehicleprovided solely for this purpose and be under the control ofthe shot firer. The vehicle should be clean internally andcarry a red flag to indicate the presence of explosives.Detonators should be separated from explosives by at least1m during carriage; explosives which have already beenfitted with detonators must not be carried in any vehicle.

8C - 4 December 2010

Detonators should be kept in a suitable container, with nometal parts that will come into contact with the detonators; itshould be kept locked until access is required. Explosivesshould be protected from the weather during transit. "NoSmoking" restrictions and a ban on the use of CB radios andmobile telephones in the immediate vicinity must be strictlyobserved.

When explosives are being transported on site, onlysufficient explosives for the work in hand should be drawnfrom the explosives store, and the vehicle carrying theexplosives should go directly to the shot holes.

When explosives are brought onto a site where there isno lawful storage facility, (as outlined under"Documentation"), liaison may be necessary between thesupplier making the delivery and site management on suchmatters as emergency arrangements and the provision ofsafe parking away from obvious sources of ignition andother dangerous goods.

Guidance on safe transport of explosives on site iscontained in sections 4.2.10 and 4.2.12 of BS 5607,“Code of practice for the safe use of explosives in theconstruction industry”.

Mixing on siteBefore explosives mixtures are manufactured on site an

application for an exemption from the Ammonium NitrateMaterials (High Nitrogen Content) Safety Regulations 2003is required. This can be obtained from the Health and SafetyExecutive Tel 020 7717 6205, the exemption relates to thedetonation resistance requirement. In addition, a smallamount of record keeping is required.

The actual mixing process itself is very simple althoughthe manufacturers advice should be sought as to theprovision and use of suitable equipment and the appropriatemixing ratios. Some further guidance on this subject can befound in BS 5607:1998.

Use of explosivesThe Construction (Design and Management) Regulations

2007 - Part 4, Regulation 30 requires that "suitable andsufficient" steps be taken to ensure that nobody is exposed torisk of injury from the use of explosives in construction work,including flying material.

In addition, persons undertaking the drilling of shot holesmust be protected from the dangers associated with work atedges from which there is a risk of falling, dust from thedrilling process, unguarded dangerous parts of machineryand the rupture of large diameter compressed air hoses.These are normally chained at the coupling to prevent themsnaking about in the event of a burst.

Code of signalsBefore any blasting takes place, both audible and visual

signalling systems, giving warning of blasting operations,should be established. These must be explained andpublicised through the site Induction Training, Site Rules andclearly visible Signs affixed at the entrances to the site.Audible warnings should consist of a series of readilyrecognisable signals, which have a distinctive sound. Visualsigns should take the form of clearly painted notices postedon all access roads and sited outside the danger area.Sentries should be posted with clear instructions as to whenthey can stop access to the site and when they can allowaccess.

Shot firingCompetence of shot firers

Both BS 5607:1998 and the Quarries Regulations 1999(revised), Approved Code of Practice set out the trainingrequirements for Shot Firers; these must be adhered to ifsafety is to be achieved.

General precautionsBefore explosives are used on any particular site, a

written system of work, applicable specifically to that site,should be prepared. The responsibilities of persons withspecific duties, such as Explosives Engineers, Supervisors,Shot firer and Sentries should be detailed in writing. TheBritish Standard (BS 5607) is very useful as it providesdetailed guidance in relation to general explosive mattersand specifically works involving tunnelling, shaft sinking,demolition, underwater blasting and land excavation. Whenthe system of work is being prepared, consideration shouldbe given to the following matters:1. The development of the Blasting Specification, Appendix

2 of the Quarries Regulations (revised) and theirApproved Code of Practice may be used as a source ofguidance in this respect. (These requirements must bestrictly followed in a quarry). Specific details of thequarries requirements can be found in section 15 of thismanual. BS 5607 deals with this matter in section 4.7under the heading "Method Statement" where it refers tothe charging plan.In practice this means that the “explosives engineer” orother competent person will produce a blast design takinginto consideration the risks identified in the site survey, thegeology of the material to be blasted, the exclusion zoneto be achieved and any blast protection required.The design will also set out the number of shot holes,position, depth and diameter, type and weights ofexplosives, the charge and stemming. Time delays(detonators) and sequencing will also be described. Theblast design will inform the blast charge schedule.It may be appropriate to carry out a trial blast to confirmhow the target responds to the blasting regime beingconsidered.

2. The preparation of Explosives Rules, based on the safesystem of work, written in a manner that can be easilyunderstood by the workforce. Matters that could beincluded in the rules are contained in the QuarriesRegulations 1999 (revised), Approved Code of Practice;(these requirements must be strictly followed in a quarry)they can be found on page 15 of this manual. The rulesand system of work must include: - The Shot Firer should make sure that the drilled holepattern and the charging and stemming conforms to theblasting plan.- The banning of cigarettes, matches and naked lightswithin a radius of 10m from explosives and detonators.This is a legal requirement in quarries. - The prohibition of drilling into old sockets, as thesemay contain explosives or detonators, which may bedetonated by a drill.- The use of only wooden rods for charging andstemming shot holes.- Shot holes should be minimum of 3mm larger than thecartridge diameter for normal holes and 13mm for deepholes. Before charging, shot holes should be proved clearby inserting a stemming rod to the bottom.- Cartridges should be inserted into the holes one at atime, and stemming should be completed only withsuitable material, e.g. sand, clay, gypsum, etc.- As high explosives are initiated by the application ofa powerful localised shock, exposure to any deliberate,accidental or random compressive action must beprevented.- The shot firing circuit must be tested (electricalinitiation only)- The establishment of a suitable exclusion zone- The posting and duties of sentries - The provision and maintenance of warning signs;where these are pictorial signs they must comply with theHealth and Safety (Safety Signs and signals) Regulations1996.

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- The need to have an audible means of giving warningthat a shot is about to be fired and to sound the all clear.These signals must be simple and well publicised.- The shot firer must also satisfy himself that the dangerzone is clear before firing a round and that, after firing, acomplete check is made to ensure that no misfires or otherhazards exist before the all clear is sounded.- Rules for dealing with miss-fires- The procedure for notifying the HSE in the event ofmaterial being projected beyond the boundary of thesite. This is a dangerous occurrence under RIDDOR- A procedure for the disposal of unwanted explosives-. The need to notify the police, the general public, oroccupiers of adjacent properties of shot firing times.

Electrical shot firingElectrical detonation allows shot firing from a remote

location and also controls the precise instant of firing, thusincreasing the safety factor. In addition, the use of timingdelay detonators in the firing circuit significantly reduces thelevels of vibration. The method is generally used as anumber of shot holes can be connected together and fired asa group.

The making up of primed charges should normally beundertaken by the shot firer immediately prior to charging. Anon-ferrous pricker must be used for piercing the explosive,making it ready to receive the detonator. On no accountmust any other form of pricker be used. Detonators must befirmly secured to the primer cartridge in such a manner as toprevent the detonator or wire becoming detached ordamaged. The ends of the detonator leads must remaintwisted together until all holes have been charged.

Where it is not possible to achieve safe conditions at thecharging place (e.g. in very wet conditions), it will benecessary for priming explosives to be transported to thecharging place. Such procedures will require additionalcareful planning.

All rock surfaces, rails, metal objects, cables etc. must beconsidered as potential sources of stray current and greatcare must be taken to prevent detonator lead wires cominginto contact with them.

Good connection of the detonator leads, connecting wireand shot firing cables is essential. Before attempting to fire ashot electrically, the shot firer must test the continuity of thecircuit with a suitable, calibrated instrument before heconnects the firing cable to the exploder. This testingprocedure must be carried out only after all persons have leftthe shot firing area and the shot firer himself is in the firingposition. The removable handle of the exploder must be keptin the shot firer’s possession at all times. The handle maybe inserted into the exploder immediately prior tofiring only and it must be withdrawn immediatelyafter firing.

After the shot has been fired, the appointed shot firer mustinspect the area of the blast for misfires, or any other sort ofdanger, before allowing people to return to the area.

When detonating near overhead electrical cables,consultation should take place with the electricity supplier,who may be able to make the cables dead for a limitedperiod. Advice should be sought on the minimum distancepermissible between an explosive charge and an overheadelectric cable. The following distances may be used forguidance:

11-70kV 20m132-400kV 61mPremature ignition of electric detonators by

electromagnetic energy from radar, radio and televisiontransmitters is a possibility which should always beconsidered and this is why CB radios and mobile telephonesshould be excluded from the shot-firing area.

Beamed transmitters, such as navigational aids andmilitary installations often operate at a high power and, ifthe station is in direct line of sight of blasting operations,

adequate investigations should be made and suitableprecautions taken. Commercial radio transmitters may bepotentially dangerous as the wavelengths used are oftensimilar to the overall length of the proposed blasting circuit.

Television transmitters are not generally a hazard as theytransmit horizontal beams from a high mast, but portablewalkie-talkie equipment and unmodified car transmitters upto 5W in output should not be taken within 10m of anyblasting operation. Modified car transmitters and CB radiotransmitters, which may have been illegally modified toincrease their power, are potentially dangerous at muchlarger distances. Users of electric detonators arerecommended to discuss this matter with the manufacturer orsupplier of their detonators. In any event, the use of CBradios on sites should be banned by notices placed at allentry points.

All legally operating transmitters are licensed by HMGovernment, e.g. Home Office, who will advise ontransmitters in any area. Information is also available frombroadcasting authorities, the Civil Aviation Authority andBritish Telecom. The Ministry of Defence may advise onmilitary installations.

Electrical means of detonation must not be used duringstorm conditions when there is thunder and lightning in thevicinity. The possibility of uncontrolled detonation should notnecessarily prevent the use of this type of firing method.However, the manufacture/supplier must be consulted toensure that the firing initiation system is appropriate for thecircumstances.

Detonating cordDetonating cord is a very reliable initiator and its use for

firing large groups of charges is free from some of thedrawbacks of electrical shot firing such as current leakageproblems. However, detonating cord must be protected fromrain and ground water as moisture penetration can causetransmission failures. Covering the ends of the cord withwaterproof tape may prove effective, but if conditions arevery wet, the use of sealing compounds may be necessary.When laying out detonating cord, it is essential to ensurethat branch lines do not cross over the main line, as ondetonation a branch line may be severed, resulting in amisfire in the shot hole which it is serving. Detonating cordmust not be kinked or knotted, otherwise transmission failuremay occur. In use, detonating cord passes down the outsideof explosive cartridges to the bottom of the shot hole, so careshould be exercised when using a stemming rod otherwisethe cord may be broken or damaged. Breakage of cord canalso result from excessive tensioning, repeated stretching orthe imposition of a sustained load. The power core ofdetonating fuse is liable to detonate, with the risk of seriousinjury if subjected to impact or shock. Detonating cordshould always be protected from friction and heat.

Shot firing using safety fuseIn surface blasting applications, the use of safety fuse is

virtually restricted to single shot-firing operations such as the"popping" of large boulders. This is because accurate timingcannot be achieved and, if used in a group, an erratictiming sequence would result. However, safety fuse may beused where it is considered dangerous to use electricaldetonation due to the presence of nearby electrical hazards.

Safety fuse is used in conjunction with a plain detonator.The fuse is inserted into the open end of the detonator, whichis secured by crimping on to the fuse. The correct crimpingtool must be used. A primed charge is made up by insertingthe detonator into a hole prepared in the primer cartridge.

The length of safety fuse must allow the shot firer andassistants ample time to walk to a place of safety afterignition. No single shots should be fired by fuse less than 1min length, nor any shot in a round be fired by fuse less than1.25m in length. A shot firer must not attempt to ignite more

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8C - 7December 2010

than six individual shots in a round. Only fuse lighters,specifically designed for the purpose, should be used.

Tunnelling and shaft sinkingThe following additional precautions are relevant to

tunnelling and shaft sinking:

StorageWhere it is necessary to store explosives in the tunnel

between blasting operations, proper reserve stations shouldbe excavated and fitted with steel doors. Reserve stationsshould not be nearer than 300m to the tunnel face. Reservestations are not authorised storage places. Any explosivesremaining in them at the end of a shift should be returned tothe licensed explosives store or magazine.

TransportExplosives should be transported to the tunnel face in a

clearly marked special mine car, lined with timber andhaving top or side lids fitted with padlocks. Explosives mustnot be carried on the driving locomotive itself.

Drilling and chargingDrilling patterns should adhere to the agreed profile. All

shot holes should terminate at the same vertical plane,except those drilled for cut shots and easers. If the presenceof gas is suspected, tests should be made at the mouth ofeach shot hole, and within 9m of the face prior to charging.Plastic water stemming, water stemming under pressure, orwater gel capsules reduce dust and toxic fumes. If possible,explosives with non-toxic characteristics should be used intunnelling operations.

No explosives or blasting accessories should beconveyed to the face until all drilling operations for the roundto be charged have been completed.

Sockets left after blastingThe most common cause of severe accidents with

explosives in tunnelling results from drilling into socketscontaining explosives which were not fired in the previousround. It is essential that drilling into such sockets be avoidedand this is why the careful inspection of the face after a blastis important.

Electrical faults and hazardsShort-circuiting or current leakage from the circuit to earth

is more likely to occur when conditions are wet. Groundwater from rock fissures often contains mineral salts, whichgreatly increase its electrical conductivity. Bare wireconnections should not be allowed to dangle in water, norbe allowed to hang against a wet rock face.

The risk of premature explosion during electric storms isparticularly high in tunnelling work. Dangerous staticcharges can also build up in compressed air equipment, andit is essential that such equipment should be positivelyearthed. Another hazard is from portable electric lightingcables; such lights should be removed to at least 9m from theface when preparing or charging blasts. Power to drillingand other equipment should also be switched off, orcompletely isolated, when explosives and detonators are inthe vicinity.

Shot firingSerious shock and flash wave effects can be experienced

in tunnel blasting work. In straight tunnel work, the minimumdistance from the face to the firing point should be at least300m. A shorter distance may be acceptable where a cross-tunnel or special refuge provides protection but, in suchcases, the dangers from ricochets and fumes must beassessed. Before the all clear is given, the shot firer mustensure that all fume has been adequately diluted or hasdispersed. This may initially require gas testing with a stain

tube detector or some other suitable testing device toestablish the timescale at which fume dilution is such that it issafe for the workforce to return to the face. This testing mustbe repeating as the work progresses and written recordskept to ensure that the re-entry timescales are appropriate.Miners are likely to be working on a bonus system andtherefore re-entry may require a strong level of control!

Scaling Down FacesAll shot-firing operations are likely to leave fragments of

loose material on the face. These can fall and have beenknown to cause injury and in some cases, where inclined,sloping rock beds in tunnelling are concerned, death. Thesemust therefore be removed or stabilised before any workinvolving an approach to the face, where there is a risk fromfalling material, can begin. A cherry picker will provide auseful platform for scaling down and the Shot firer should notallow anyone to approach a face until he is satisfied that theface has been inspected and loose material cleared.

MisfiresElectrical shot firing misfires

If an electrically initiated charge fails to fire, the shot firermust follow the following procedure: -1. Remove the handle from the shot firing apparatus and

keep it on his person.2. Disconnect the cable from the shot firing apparatus.3. After waiting 5 minutes, examine and re-test the shot

firing cable and connections for any defect. If one isfound, it must be remedied.

4. Return to the firing point and make a further attempt tofire the shot.

5. If this second attempt to fire is unsuccessful, the circuitshould be split in half and each half should be tested inturn to locate the fault.

6 Advise his superviser of the situation.7. The faulty half should then be split in two and again each

half should be tested separately by continuing thisprocess, the fault can be located. All such tests must beaffected from the firing shelter.

8. Once the faulty detonator has been located, theremainder of the circuit should be connected in series,omitting the faulty detonator. The leading wires of thefaulty detonator should be connected by string to asuitable marker to facilitate recovery of the primercartridge after firing.

9. After re-testing, the modified circuit should be fired.Dislodged material should then be searched for anyundetonated cartridges. Recovered explosive materialmust be kept in a safe place with detonators being keptseparate from explosive materials.

10.If material in the vicinity of the misfired hole is notdislodged by the blast, recovery of the misfired chargemay be attempted by firing shot relieving holes at adistance of at least 300mm from the misfired charge. Asimilar procedure should be adopted if a misfire is foundafter a blast has been fired.

11.Where misfires are encountered after firing a round, theface or structure is likely to be fractured and weakened.Any dangerous conditions must be rectified before theshot firer deals with the misfire.

12.Do not allow persons to approach the shot-firing area orface until he is satisfied that it is safe.

Safety fuse misfiresIn the event of a misfire, the shot firer must adopt thefollowing procedure:-

1. Ensure that no one approaches the shot firing area until atleast 30 minutes have elapsed.

2. At the expiration of the 30-minute period, inspect thesafety detonation fuse and, if the cause of the misfire is

clearly evident, rectify the fault and make a secondattempt to fire the round.

3. If this second attempt to fire is unsuccessful, the shot firermay adopt one of the following procedures: -(a) Remove the stemming by compressed air, or water,

using a non-ferrous or rubber blowpipe. Insert aprimer cartridge into the hole, re-stem and fire, or

(b) Drill a relieving hole at least 300mm away from themisfired charge, taking care to ensure that this hole isdrilled parallel to the misfired hole. Load and fire therelieving hole in the normal way.

After either of these procedures has been followed, amost careful search must be made of the debris fordetonators and unexploded explosives.

Records of misfiresRecords should be kept of any misfires, in the case of a

Quarry this should be in accordance with Regulation 28 ofthe Quarries Regulations 1999. Misfires are also reportableunder the RIDDOR Regulations 1995 as a dangerousoccurrence.

Disposal of explosivesThe Manufacture and Storage of Explosives Regulations

2005 require that explosives are disposed of safely and in adesignated area. Therefore extreme care must be taken inthe disposal of unwanted, or apparently deterioratedexplosives. In general, explosives should be returned tomanufacturers or suppliers although substances such asgelignite can be burned Manufacturers guidance is essentialin this respect and the persons involved should avoid thefumes as they produce severe headaches. Guidance is alsocontained in booklet HS (G) 36 Disposal of explosives wasteand the decontamination of explosives plant. In addition, ajoint publication by the HSE and The Explosives IndustryGroup (EGI) has been produced. This is entitled, “Guidancefor the safe disposal of explosives”. Information about thispublication can be found on the EIG web-site.

All empty explosive boxes must be thoroughly examinedby the shot firer, taken to a safe place, at least 50m from thestore or magazine, and burned.

8C - 8 December 2010

8C - 9December 2010

LegislationCarriage of Dangerous Goods by Road (Driver Training)

Regulations 1996Carriage of Dangerous Goods by Road (Safety Adviser)

Regulations 1999Carriage of Explosives by Road Regulations 1996Chemicals (Hazard Information and Packaging for Supply)

Regulations 1994Classification and Labelling of Explosives Regulations 1983Construction (Design and Management) Regulations 2007Control of Explosives Regulations 1991Control of Pollution Act 1974 Sections 60 & 61

(neighbourhood noise)Dangerous Substances in Harbour Areas Regulations 1987Explosives Act 1875 and 1923 (this is gradually being

replaced by more modern legislation)Explosives Act 1875 etc. (Metrication and Miscellaneous

Amendment) Regulations 1984Health and Safety (Safety Signs and Signals) Regulations

1996Management of Health and Safety at Work Regulations

1999Manufacture and storage of explosives regulations 2005Packaging of Explosives for Carriage Regulations 1991Placing on the Market and Supervision of Transfers of

Explosives Regulations 1993Quarries (Explosives) Regulations 1999Reporting of Injuries, Diseases and Dangerous Occurrences

Regulations (RIDDOR) 1995Ammonium Nitrate Materials (High Nitrogen Content)

Regulations 2003Manufacture and Storage of Explosives Regulations 2005

Approved Codes of PracticeDangerous substances in harbour areasHealth and safety in quarries, L118Manufacture and Storage of Explosives Regulations 2005

L139Suitability of vehicles and containers and limits on quantities

for the carriage of explosives (HSE booklet L91)Approved Requirements for the construction of vehicles

intended for the carriage of explosives by road (HSEbooklet L92)

British StandardsBS 5607 Code of practice for the safe use of

explosives in the construction industryBS 5930 Code of Practice for Site InvestigationsBS 4142 Rating Industrial Noise Affecting Mixed

Residential and Industrial AreasBS 6031 Code of practice for earthworksBS 6164 Code of practice for safety in tunnelling in

the construction industryBS 6187 Code of practice for demolitionBS 6657 Guide to the inadvertent initiation of electro

explosive devices by radio frequencyradiation

GuidanceHSE Website hse.gov.uk/explosives/index.htmEIG web-site www.eig.org.ukHSE Guidance booklets:HS (G) 36 Disposal of explosives waste and the

decontamination of explosives plantHSE/EIG Guidance for the Safe Disposal of ExplosivesHS (G) 114 Conditions for the authorisation of explosives

in Great BritainHS(R) 17 A guide to the Classification and Labelling

of Explosives Regulations 1983HS(R) 27 A guide to the Dangerous Substances in

Harbour Areas Regulations 1987L10 A guide to the Control of Explosives

Regulations 1991L13 A guide to the Packaging of Explosives for

Carriage Regulations 1991L91 Suitability of vehicles and containers and

limits on quantities for the carriage ofexplosives. Approved Code of Practice.

L92 Approved requirements for the constructionof vehicles for the carriage of explosives byroad.

HSE Leaflets:IND (G) 115 An introduction to the Control of Explosives

Regulations.CIS 45 (revised) Establishing exclusion zones when using

explosives in demolition.

TrainingA list of training establishments offering courses on the

use of explosives is given in BS 5607 Appendix B.

All of the above reference material is available from:Construction Industry Publications Ltd.,c/o BTB Mailflight Ltd, 2B Viking Industrial Estate, Hudson Road, Bedford MK41 0QBTel: 0870 078 4400Fax: 0870 078 4401e-mail sales@cip-books.com

REFERENCES

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