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Project 4 » 2. Hazard Identification and Risk Management by Country » 2.4. India » 2.4.3. Risk Management
2.4.3. Risk Management
There is some use made of the Job Safety Analysis process of identifying hazards and implementing risk controls.
A risk management protocol is being applied to mines and consists of a simple methodology:
identify the hazard
rank the risk using probability x consequence x frequency, and based on some established nominal values
develop a safety management action plan to manage the risks
develop monitoring and review parameters
conduct a periodic review.
Case Example
There is a high risk rating of accidents due to inundation in Indian mines due to several factors; such as presence of old water logged workings, Inaccurate mine survey plan, improper survey instruments, inundation from surface, collapse of pillars due to fires, old galleries not shown on plan and breaching of flood protection dams. Hence a model Safety Management plan for inundation is to be developed. The steps involved in preparation of the Safety Management Plan (SMP) for Inundation are:
Step 1: Identification of the mechanism in which the inundation can occur.
Step 2: Calculate the risk rating as per the model suggested in Table 10. The calculated risk rating is shown in Table 12.
Step 3: Review of the existing control to reduce the risk and identify the new controls.
Step 4: Device the procedures for implementing the controls
Step 5: Identification of the responsibilities for the control procedures.
Table 12 Risk rating for inundation (DGMS)
|
Mechanism |
Conseq. |
Exposure |
Probab. |
Risk |
|
Pillar failure due to fire allows connection with surface water body |
5 |
10 |
7 |
350 |
|
Failure of river bank during heavy rain |
5 |
10 |
7 |
350 |
|
Failure of drift dam 10 to 11 Seam |
5 |
10 |
7 |
350 |
|
Surface flooding or water body enters through goaf or mine entries |
5 |
5 |
7 |
175 |
|
Barriers against flooded old workings failing under hydrostatic pressure |
5 |
10 |
3 |
150 |
|
Accidental holing into old flooded workings |
5 |
5 |
2 |
50 |
|
Failure of river bank due to damage from mine subsidence |
5 |
10 |
1 |
50 |
|
Pillar failure or creep allows goaf formation to connect with water body/aquifer |
5 |
10 |
0.5 |
25 |
|
Roof fall in development workings taps overlying aquifer or water accumulation |
5 |
1.5 |
2 |
15 |
|
Workings intersect geological structure providing water flow channel |
1 |
2 |
1 |
2 |
|
Workings intersect open boreholes |
0.1 |
2 |
7 |
1.4 |
|
Goaf development/cracking to surface due to mining |
0.1 |
2 |
2 |
0.4 |
|
Workings intersect aquifer |
0.1 |
1.5 |
0.5 |
0.075 |
In the exercise, Steps 3, 4 and 5 are done for the three highest risk rated inundation hazards i.e.
Pillar failure due to the fire and connection of underground workings with the flooded rivulet flowing in the surface
Failure of river bank due to the heavy rain
Failure of the water dam or seam parting in underground connecting the workings with water logged areas.
The details of the existing controls and the possible new controls for each of the above risks due to inundation of water are shown in Table 13.
The next step after identifying the new controls for reducing the risk of the hazard happening is to prepare the action plan defining the action/procedure for implementing the controls and assigning time frames and responsibilities.
Table 13 Controls for inundation (DGMS)
|
High risk hazard |
Current controls |
Possible new controls |
|
Pillar failure due to fire and inundation from surface river (Risk rating: 350 out of maximum 500) |
Borehole filling with concrete of roadways around pillar beneath river. |
Install subsidence monitoring stations around area |
|
No more mining under river |
Define extent of fire and effect of remedial work by monitoring temperature and goaf gas. |
|
|
Daily inspection of surface area for subsidence effects |
Construct culvert drain over river bed |
|
|
Filling cracks in river bed with grout |
River diversion to new course unaffected by underlying workings |
|
|
Monitoring and recording of u/g water levels |
Re-line original river bed with concrete and re-divert river to original course |
|
|
Pumping to maintain required water levels |
Formal development of Emergency Evacuation Plan |
|
|
Water Danger Plan with warning level specified as standing order |
Provision of emergency dewatering pump system |
|
|
Standing order for emergency mine evacuation (with water level trigger) |
Training of workforce in inundation management plan |
|
|
Failure of river bank due to heavy rain |
Inspection by Manager |
Increase bank to comply with statutory specs (3mabove HFL) |
|
Top of bank constructed 1.5m above HFL |
Engineering appraisal to test strength and identify critical sections of bank |
|
|
Some sections reinforced with concrete wall |
Increase concrete reinforcement |
|
|
Maintenance of bank to maintain dimensions |
Widen the bank and reinforce key areas |
|
|
24 hour watch during monsoon period |
Desilting of river bed at upstream side |
|
|
Additional lighting for observation at key sites |
Training of workforce in inundation management plan |
|
|
Overflow provision with old river course during heavy rain |
Flood flow alarms |
|
|
Inflow of water from underground workings |
Water Danger Plan 10 Seam with warning level specified |
Evaluate possible sites to construct back-up or alternative dams |
|
Monitoring and recording of water levels in all the Seams |
Barrier pillars to protect dam marked on plans for mining in lower seams |
|
|
Standing order for emergency mine evacuation (with water level trigger |
Formal development of Emergency Evacuation Plan |
|
|
Review Water Danger Plans |
Provision of emergency dewatering pump system |
|
|
Simulated evacuation exercises |
|
This procedure also meets the basic requirements prescribed in the ILO code for hazard identification and risk assessment.
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