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Falls of Ground Incidents - Reporting Year 2001/2002

Contents

Introduction

1. This report summarises the fall of ground dangerous occurrences and major injury accidents at mines during the 2001/2002 reporting year.

2. All statistics are provisional.

Dangerous Occurrences

3. "Any fall of ground not being part of the normal operations at a mine, which results from a failure of an underground support system and prevents persons from travelling through the affected area by a fall of ground or which otherwise exposes them to danger", was introduced as a dangerous occurrence at Part II/40 in RIDDOR 1995, with effect from April 1996. This is the sixth full year that such incidents have been reported to HM Inspectorate of Mines.

4. Four falls of ground dangerous occurrences were reported at mines during the year, one at a coal mine, two at a large miscellaneous mine and one at an old mine where roadways were being supported to give stability to the surface.

5. In coal mines the one fall of ground occurred in a main intake roadway supported by roof bolts, that had been developed to access reserves in a new seam. A longwall face was worked in another seam some 60m and this resulted in some redistribution of the maximum horizontal stress and the roadway lost confinement and dilation of the roof occurred within the bolted height. Remedial works were carried out but some weeks after this movement occurred a tell tale outbye of the affected area began to show movement of more than 25 mm within the bolted height. A no road barrier was erected until remedial work could be carried out. The roadway subsequently collapsed. If the managers monitoring scheme for the mine had been complied with and action taken promptly then the fall may have been prevented.

6. Two falls occurred in a large miscellaneous mine in main access roads. The sections of the roads that subsequently collapsed had been identified as suspect by the geotechnical engineer. The setting of passive support was recommended in one road and before the work was carried out it collapsed at a junction area. The second road was identified but not given any priority and it again collapsed before remedial work was carried out.

7. The other fall of ground occurred in a mine where wooden supports were being set as part of a ground stabilisation exercise. The fall occurred in front of the supports that were being set and dislodged the last two sets of permanent support.

Type of Support
Miscellaneous 3
Rocketbolt 1
Total 4
Warning of Collapse
Less than 24 hours 1
Over 24 hours 3
Total 4
Age of Excavation
Recently driven -
6 - 12 months 1
2 to 3 years 2
Over 5 years 1
Total 4
Type of Excavation
Junction -girders -
Junction - natural support -
Junction - props and bars -
Roads - arches -
Roads - props and bars 1
Roads - rockbolts 3
Total 4

Accidents

8. There was one fatal accident recorded this year. A contract workmen was fatally injured after being struck by a fall of coal from the face of a passively supported development drivage. The coal fell from a fault that had encroached into the road. Temporary support was not being set in accordance with the managers support rules.

Five major injuries were reported at coal mines compared with thirteen major injuries in the previous year. There was two major injuries reported at miscellaneous mines compared with one last year.

9. At coal mines two of the accidents occurred in places supported by free standing supports, one on a longwall face and two in places supported by rockbolts. Improvements to the managers temporary support rules, adherence to on site risk assessments coupled with good mining practice would have prevented the accidents.

10. In coal mines four of the accidents occurred from falls of roof, three in developments and one when working on the AFC on a longwall face. A fall from the face accounted for the other accident.

11. In miscellaneous mines the accidents occurred in bord and pillar workings supported naturally, one from a fall of roof and the other when the face fell.

2000/2001 2001/2002
All mines fall of ground accidents Fatal Major injury Fatal Major injury
Coal mines - free standing supports - 8 1 2
Coal mines- powered supports - 3 - 1
Coal mines- rockbolts - 2 - 2
Miscellaneous mines - 1 - 2
Total - 14 1 7
2000/2001 2000/2001
Coal Mines - place of accident Fatal Major injury Fatal Major injury
Longwall face - 8 - 1
Headings - 4 1 4
Elsewhere - 1 - -
Total - 13 1 5

Conclusion

12. This is the first fatal accident reported since 1997. There has been a welcome reduction in major injury accidents in coal mines from 13 last year to five this year. The major injuries in miscellaneous mines has increased from one to two. Although there has been a welcome decrease in major injuries in coal mines the major cause of accidents this year has again been due to lack of caution or failure to comply with good practice or comply with codes or rules.

13. The incidence of falls of ground reported in coal mines has reduced from five to one.

14. The incidence of falls of ground has increased in miscellaneous mines from one to three. Two of the falls of ground occurred at the same mine and in similar circumstances.

J Arthur
HM Inspector of Mines
2012-11-27