This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Falls of Ground Incidents - Reporting Year 2002/2003

Contents

Introduction

1. This report summarises the fall of ground dangerous occurrences and major injury accidents at mines during the 2002/2003 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.

4. Six falls of ground dangerous occurrences were reported at mines, three at coal mines and 3 at one miscellaneous mine.

5. In coalmines two falls of ground occurred at the one mine at junction areas of roadways that were over 20 years old, one supported by steel and the other by props and bars. The immediate roof had degraded and caused the support to fail. The roadways had been used as auxiliary airways and were not needed strategically for the ventilation of the mine. If the roads are not needed then they should be sealed off. The other fall occurred on a face line, supported by passive steel supports supplemented with roof bolts. The tell tale monitoring showed increasing levels of dilation. The tell tale readings were ignored because it was mistakenly thought that the steel support would support the roof and no action needed to be taken. When mixed support systems are used any movement recorded by monitoring should be acted upon to stabilise the affected area.

6. Three falls occurred at one miscellaneous mine. The falls occurred in roadways driven in 1997 in roadways driven below the main mining horizon. In one roadway remedial work had been recommended by the mine geotechnical engineer but not carried out. The omission was not detected and the road subsequently collapsed. In another a fall occurred in a cross connection off a main road. The mine risk assessment programme was to be extended to include these types of roadways. The support strategy at this mine was to be reviewed and detection skills of supervisors improved.

Type of Support
Miscellaneous 3
Steel arch 2
Mixed systems 1
Total 6
Warning of Collapse
Less than 24 hours 1
Over 24 hours 2
No warning 3
Total 6
Age of Excavation
Recently driven 1
6 - 12 months -
2 to 3 years -
Over 5 years 5
Total 6
Type of Excavation
Junction -girders -
Junction - natural support -
Junction - props and bars -
Roads - arches 2
Roads - props and bars 1
Roads - rockbolts 3
Roads - mixed systems -
Total 6

Accidents

7. There were no fatal accidents recorded during the year.

8. Two major injuries were recorded at coal mines this year compared to five last year. There were no major injuries recorded at miscellaneous mines, two were recorded last year.

9. Both major injuries at coal mines occurred in roadways supported by passive steel supports. There were no injuries recorded in roadways supported by rock bolts.

10. One accident occurred when a workman was setting a German TH type arch leg and a stone fell from the roof and struck him. The other occurred when a workman was assisting to install a large junction girder when a stone fell and slid down a mesh panel and struck him. Then introduction of temporary support systems (similar to mesh cages in roof bolted systems) to prevent injuries from falls of the roof or sides when passive arch type supports are being installed.

2001/2002 2002/2003
All mines fall of ground accidents Fatal Major injury Fatal Major injury
Coal mines - free standing supports 1 2 - 2
Coal mines- powered supports - 1 - -
Coal mines- rockbolts - 2 - -
Miscellaneous mines - 2 - -
Total 1 7 - 2
2001/2002 2002/2003
Coal Mines - place of accident Fatal Major injury Fatal Major injury
Longwall face - 1 - -
Headings 1 4 - 2
Elsewhere - - - -
Total 1 5 - 2

Conclusion

11. There were no fatal accidents reported during the year.

12. There has been a reduction in major injuries from seven last year to two this year. An industry wide working group is pursuing the provision of temporary support systems to prevent injury in roads supported by passive supports.

13. There were no accidents reported in roadways supported by rock bolts even though this support system is used to support approximately 80% of all roads being driven.

14. The incidence of falls of ground reported in coal mines has increased from one to three. One particular fall of ground occurred on a face line supported with steel supports supplemented with roof bolts where monitoring information was ignored. If roof bolts are used as part of the support system then tell tales should be installed and action taken if dilation above accepted levels is recorded. The other two were in old roads. Surveys should be carried out and any roads not required should be sealed off.

15. The incidence of falls of ground in miscellaneous mines has remained at three. This is concerning because the three falls of ground all occurred at the same mine and in similar circumstances. This mine also accounted for two of the falls of ground reported last year, again in similar circumstances. Remedial work recommended by the geotechnical engineer is being prioritised and acted upon and systems implemented to check that the work has been carried out.

J Arthur
HM Inspector of Mines

2012-11-27