Identifying Significant Hazards
Regulation 54 Safety, Health and Welfare at Work (Quarries) Regulation 2008
Regulation 54 of the Safety, Health and Welfare at Work (Quarries) Regulations 2008 requires the Operator to have a suitable appraisal of all proposed and existing excavations, tips and lagoons
undertaken by a competent person. The frequency of appraisals should be identified in the Operating procedures for the Quarry. The appraisal should identify any significant hazards or potential significant hazards and determine if they can or cannot be rectified immediately in a safe manner.
Any hazard or potential hazard should be considered significant or potentially significant if such a failure would directly or indirectly, be liable to endanger premises, roadways or other places where people are likely to be found off site; or likely to cause serious or fatal injuries to persons on or off -site. If the competent person is unable to determine if a hazard or potential hazard is significant or potentially significant they should seek the advice of a geotechnical specialist.
The following diagrams provide guidance to scenarios where a hazard should be considered significant or potentially significant
|Working faces of sand and gravel or other weak materials such as clay where the vertical face height (H) is in excess of 7.5 metres and the overall face angle is steeper than a suitable angle to ensure safety should be considered to be or potentially be a significant hazard. The natural angle of repose considered by extractive industry best practice as a suitable angle to ensure safety in unconsolidated material is as low as 270 or 1 in 2.|
Where the face height of an excavation in a particular area of a quarry is worked or is planned to be worked
exceeds 20 metres then this is a significant hazard and the Operator must ensure that a geotechnical assessment is carried out.
There are no mitigating factors, a geotechnical assessment is mandatory.
Where multiple benches have been worked or are being worked and the bench widths or the overall face angle may be inadequate to ensure quarry stability then this should be considered a significant or potentially
The extractive industry best practice is an overall face angle of 450 or 1 in 1 though this depends upon local
Based on extractive industry best practice the quarry face may also potentially be considered a significant hazard if the overall bench height (Hb) is greater than 30m.
If there is a structure, tip or stockpile close to the quarry face edge it should be considered that this is a significant or potentially significant hazard irrespective of any excavation face height, depth or angle, other factors, for example, the geology, location or proximity of a tip, location or proximity of infrastructure or private lands.
Although no minimum distance of encroachment of a quarry face to a structure, tip or stockpile is specified in the regulations any distance (L) less than 30 metres should be considered a significant or potentially significant hazard based on extractive industry best practice.
|An appraisal of a tip or stockpile should indicate that the tip or stockpile should be considered a significant or potentially significant hazard if it has a vertical height in excess of 20 metres.|
An appraisal of a tip or stockpile should indicate that the tip or stockpile should be considered a significant or potentially significant hazard if the area of the land covered by the tip or stockpile exceeds 10,000 square metres.
The calculation of the area of the tip or stockpile will be dependent upon the shape of the tip or stockpile, for the illustration a simple rectangle has been used.
|An appraisal of a tip or stockpile should indicate that the tip or stockpile should be considered a significant or potentially significant hazard if the average gradient of the land covered by the tip or stockpile exceeds 1 in 12 (8.3%)|
An appraisal of a pond or lagoon should indicate that the pond or lagoon should be considered a significant or potentially significant hazard if the volume of liquid contained exceeds 10000 cubic metres
As an example a pond/lagoon 2.5 metres deep with a width of 50 metres and a length of 80 metres when full would contain 10000 cubic metres of liquid