An introduction to using bowtie risk management techniques and a description of software that can accomplish the task.Full description
CSMM101 – Hazard and risk management
Bow tie method for risk assessment
Bow tie method for risk assessment as sessment of possible explosion in a coal mine Hazard
Threat
Control Measures 1. 2. 3.
1
Stored Methane
Puncturing of a methane Pocket in the coal seam
4.
5.
Accumulated coal dust
E x p l o s i o n
1.
Drainage of entire coal seam Drainage of coal seam above and below the active working Appropriate pillar design to prevent floor heaving Scaling of floor and roof Gas detectors at intervals in mine Visible inspection for zones of weakness (on – shift/Pre Shift)
i n
1.
t h e
3.
m i n e
6.
Electrical Machineries 1. Coal as a combustible
2.
Heat and fire due to friction
3.
People 2
Mechanical Energy
Methane Inundation from floor/roof
4. 5. 6.
Stored water
3
Accumulation of Methane on roof of
1.
Recovery Measure
Drainage of entire coal seam Drainage of proposed coal seam before working Drilling of test holes to search for gas pockets in mine Continuous monitoring of methane concentration at seam using gas detectors Pre – mining drainage monitoring to identify gassy seams
Pre Shift/on shift evaluation of roofs using potable gas
2. 3. 4. 5. 6. 7.
2.
4. 5.
7.
8.
1.
Evacuation of the workers at mine Shutting down of stopping doors/airlock Increased flushing of fresh air to dilute excess methane Termination of power supply to equipment Emergency Response plan in action Mine Rescue team on standby All employees equipped with Self contained self rescuers Evacuation of Workers at mine Sealing of affected areas with stoppings/airlock Increased flushing of fresh air to dilute excess methane Termination of power supply in the affected area Emergency response plan in action Mine Rescue team on standby. Sealing of floor/ roof cracks after flushing off excess methane. All employees equipped with self contained self rescuer Use of ventilation ducts to flush accumulated roof
Consequence Consequence 1. 2.
3. 4. 5.
1. 2.
3. 4. 5.
1.
Asphyxiation due to lack of oxygen Small scale methane explosion due to spontaneous combustion of coal Coal seam fire Injury and possible fatality of workers Loss of Property
Asphyxiation due to lack of oxygen Methane explosion due to spontaneous Combustion of coal Coal seam fire Injury and possible fatality of workers Loss of property
detectors Auxiliary ventilation to push air through areas of difficult reach Scaling of roofs to allow as laminar ventilation flow as possible Ventilation layout to suit entire cross section of working Airflow simulation studies Use of overcast against stoppings and airlock Training of Ventilation staff for best work practices Tandem airlocks which do not allow both doors to be open at same time Periodic Maintenance of fans Periodic maintenance of fans On-shift/pre shift examination to study blockages in ventilations networks Real time monitoring of airflow Auxiliary fans in place for additional ventilation requirements Use of two fans for push and pull to be used in case of failure of one Pre shift/on shift examination of working to inspect for blockages or roof collapse Periodic maintenance of Fans Preventative Maintenance system in place for main
Recovery Measure
E x p l o s i o n i n t h e m i n e
2. 3.
1. 2.
3. 4.
5. 1. 2. 3. 4. 5. 6.
1. 2. 3. 4. 5. 6.
methane Emergency Response Plan in Action. Employees equipped with self contained self rescuer
Use of emergency fan for ventilation Use of auxiliary fans to force air through needed areas House Nurse on duty Change in ventilation requirement from real time monitoring Employees equipped with self contained self rescuer Evacuation of mine workers Spare fan in place for sustaining ventilation Emergency response plan in action House Nurse on duty Mine rescue team on standby All employees equipped with self contained self rescuer Evacuation of Mine workers Spare equipment in place House Nurse on duty Emergency response plan in action Mine rescue team on standby All employees equipped with self contained self rescuer
Consequence 2. 3.
1.
2. 3. 4.
1. 2. 3. 4. 5. 6. 1. 2. 3. 4. 5. 6. 7.
combustion Injury and possible death of workers Loss of property
Methane flooding leading to asphyxiation and explosion Rise in temperature of the mine Injury and possible fatality of workers Loss of property
Rise in temperature in the mine Drop in oxygen levels Increased methane flow Possible Methane Explosion Injury and possible death of people Loss of property Drop in oxygen Methane built up Asphyxiation of workers Rise in mine temperature Possible Methane explosion Injury and possible death of workers Loss of property
Flooding of workings leading to obstructive ventilation
4. 5. 6.
1. 2.
3. 8
Large Suspension of float coal dust in entries
4.
5. 6. 1.
2. 9
Rise in temperature 3.
ventilation fans Auxiliary fan network to force air in required areas Series of pump installation at sumps to avoid flooding Sealing of old mine workings Proper roof /floor/pillar design to prevent inundation due to cracking Air flow simulation and real time monitoring Periodic gas measurements of sealed mine workings On shift/pre shift examination Intermixing of stone dust with the dust stream Use of high pressure water mist to reduce suspended coal dust Spraying of water on belt conveyors and tailgate to reduce suspended dust Ventilation design to flush out suspended dust particles Periodic inspection of faces prone to coal dust On shift/pre shift examination Rigorous checks to contain spontaneous combustion of exposed coal Ventilation air adequately cooled to provide proper working condition All diesel operated equipments to undergo checks to meet standards suitable to work in coal mine.
Recovery Measure
E x p l o s i o n i n t h e m i n e
1. 2. 3. 4. 5.
Spare pumping equipment in place Evacuation of workers. House nurse on duty Mine rescue team on standby Emergency response plan in action
Consequence
1. 2. 3.
4. 5.
6.
1. 2. 3. 4. 5. 6.
Stone dust barriers to contain explosion Evacuation of mine workers Emergency response plan in action House nurse on duty Mine rescue team on standby. All employees equipped with self contained self rescuer
7. 1.
2.
3.
4.
1.
2. 3. 4.
Flushing of air to control temperature/flush exhaust gases House nurse on duty Evacuation of mine workers. Emergency response plan in action
5. 1.
2.
3. 4.
Submersion of safety equipments Drop in ventilation Asphyxiation of workers due to drowning Rise in mine temperature Methane built up (less likely to explosion) Injury and possible death of workers Loss of property Coal dust explosion triggered by small scale methane explosion Opening of sealed mine workings leading to methane inrush Injury and possible death of people by blast Death of people by asphyxiation due to carbon monoxide Loss of property Rise in temperature leading to heat stroke/ nausea Ignition of methane/coal dust leading to explosion Injury and possible death of people Loss of property
Exhaust of equipments monitored to mitigate heat generation All equipment to meet explosion proof standards Strict adherence to ‘no smoking policy underground’ Shearers/cutters fitted with water nozzles to douse any ignition Maintenance of cutter bits to prevent spark generation due to blunt bits Methane monitors on cutting equipments
Recovery Measure
1. 2. 3. 4. 5. 6. 7.
Stone dust barriers to contain explosion Water nozzle to douse open flame Evacuation of workers House nurse on duty Emergency response plan in action Mine rescue team on standby All employees equipped with self contained self rescuer
Escalation Factor
2. Failure of coal drainage system
3.
4. 5. 1. 2. 2
Malfunctioning of methane detectors
3. 4.
1. 3
Malfunctioning of Auxiliary fans
1. 2. 3. 4. 5.
Explosion of methane/coal dust. Asphyxiation of workers Injury and possible death of people Damage to equipment Loss of property
Escalation Factor 1.
1
Consequence
2.
Drainage pipes maintained regularly Pressure of methane monitored in real time Preventative maintenance system in place for drainage network Drainage pipes of adequate factor of safety Periodic inspection Purchase of approved detectors Periodic examination of detectors Use of multiple detectors at interval Adequate training of employees in using detectors Purchase of fans of approved standards Periodic maintenance of fans
1. 2. 3.
1.
2. 3.
1. 2.
Construction of refuge chambers underground Periodic inspection of escape routes Use of alternate/multiple escape routes
Alternate arrangement of nurse on announced absence First aid training to employees Close contact with nearest hospital/clinic
Rigorous training for emergency preparedness Mock drills for emergency preparedness
Periodic checks for faults in ventilation ducts Placement of ducts near roof to avoid damage Periodic monitoring of float dust and requirements of stone dust
1. 2.
3. 1. 2. 5
Failure of pumps
3.
Use of multiple pumps Preventative maintenance of pumps On shift/pre shift examination
1. 2. 3. 4.
1. 2. 6
Clogging up of water nozzles
3.
1. 7
Human error
2. 3.
Filtering of spray water Periodic checks of spray nozzles On shift/pre shift examination
1. 2. 3.
Periodic maintenance of self rescuers Checklist for equipment assessment before entering the mine Training in proper use of self rescuers Training by certified bodies (MSHA etc) Mock drills Periodic maintenance of safety equipments Multiple rescue teams to ensure availability Approved designed standard of dust barriers Periodic maintenance of dust barriers On shift/pre shift examination
Malfunctioning of SCSR
Poor execution by Mine Rescuers
Ineffective stone dust barriers
Employee selection based on job suitability Training and assessment of employees Supervision and feedback
Preventative Maintenance plan of equipment Breakdown Maintenance
4
5
Safety checks for equipment
6
Emergency Response Plan
7
Training in best practices
8
Mine rescue training
Responsibility distribution 1. Carried out by panel foreman 2. Mine workers report the shortcoming to panel foreman 3. Shortcoming recorded in shift book and informed to management over phone or the same day depending on severity 1. Carried out by panel foreman 2. Shortcomings recorded in shift book 3. Workers allowed to enter the mine once the remedial measures have been taken 1. Prepared by Management in co operation with equipment operators 2. Shortcomings noted in log book and reported to management 3. Equipment to be used once remedial measures in place 1. Carried out by trained professionals 2. Equipment to be used once completely repaired 3. Checklist by operator before using the equipment 4. Carried out by the operator in a form every time before using the equipment 5. Shortcomings reported to the management 6. Equipment to be used once remedial measures in place 1. Prepared by management 2. Communication to workers through rigorous training 3. Mock drill scheduled by management in co operation with panel foreman 1. Arranged and scheduled by management 2. Carried out by in house health and safety department or external trainers 3. Refresher training and assessment carried out by management 1. Personnel selected by management in co operation with supervisors/foreman 2. Training carried out by certified bodies 3. Safety equipment procured by management 4. Maintenance of equipment as per the preventative maintenance and breakdown maintenance scheme
