Rev. November 10, 2020
Waste and Stockpile Conditions
This document has been developed to assist workers who create inventories of stockpiled materials and to enhance employee awareness of hazards around stockpiles and to comply with current health and safety legislation.
Waste and Stockpile Conditions Standard
Stockpiles as working hazards
Every year, workers are injured or killed when working on or around stockpiles. Large quantities of heavy material may suddenly be released from stockpiles when least expected and the energy generated in such a slide has the potential to seriously injure or kill workers and destroy equipment. Slides are most often
released from stockpiles when the material remaining after an excavation is left at an angle greater than the "angle of repose" for that material. Heavy rain, freeze/thaw conditions and other factors may also increase the probability for a run-of-material.
Angle of repose
The angle at which material in a stockpile tends to remain at rest.
A stockpile is said to be stable when the angle of its sides, relative to the pad on which it sits, matches the angle of repose for the material in the pile. The angle of repose depends on several conditions;
• The size and shape of the pieces of material in the stockpile; each type of sand or size of crushed stone has a different angle of repose
• The water content of the material
• The flatness and stability of the stockpile pad
• Temperature; frozen stockpiles present exceptional hazards
• Snow and/or ice cover on stockpiles
• Degree of compaction
Workers must be trained to recognize, assess and control stockpile hazards. The knowledge gained from reviewing this standard will assist in the successful completion of specific surface miner modular training requirements.
Postings, barriers and notices
Impending weather conditions such as heavy rain, frost, snow may affect the stability of stockpiles. Supervisors will ensure that all workers on the project are made aware of how current weather conditions could affect the stability of stockpiles. Safety notices for aggregate pits and quarries should be posted prior to entering the work area and should be maintained in a clean and readable condition at all times.
Barriers and berms are to be in place to prohibit entry of personnel or vehicles into restricted or hazardous areas. These are not to be breached, moved or modified in any way unless under the direct authority of a supervisor. Drivers of all vehicles must obey and follow all traffic procedures in the stockpile area.
The Site Plan
Where practical, a plan view drawing for the entire site should be posted and up-dated whenever any major change is made to structures, stockpiles or roadways. Aerial photographs may be used to identify characteristics of the site.
Laying out stockpiles or waste piles
All stockpiles should be located in designated areas according to the site plan.
· Pads for stockpiles shall be prepared on level ground
· Pads shall be constructed of compacted aggregates, asphalt paving or concrete according to the type and amount of material to be stored
· Pads shall be constructed to provide maximum drainage of rainwater
· Stockpiles shall be situated to provide safe loading operations with access to all sides of conical piles and the full face of horizontal piles
· Stockpiles shall be maintained to prevent any flow of material onto roadways
· Material dropped or spilled onto roadway surfaces should be removed immediately
· The maximum height of any stockpile shall not exceed a specified height to be determined by a geotechnical assessment as performed by a qualified professional engineer
· Stockpiles of unconsolidated material shall be inspected for hazardous conditions regularly by a competent person and made safe before a worker is allowed to work close to or on top of the stockpile
· Bulk or packaged material shall be piled or stacked in a manner to prevent accidental movement or collapse
· When a tunnel is used under a stockpile for the purpose of reclaiming the material from the stockpile, at least two exits shall be provided for the tunnel
Excavation of a linear stockpile shall proceed along the base and working face of the pile such that the risk of material running down a secondary slope towards the side of the excavating equipment is reduced. Excavation of a conical stockpile shall proceed progressively around the toe of the pile.
Where earth, clay sand or gravel is being removed from a waste or stockpile by powered equipment, the working face shall be sloped at the angle of repose or the vertical height of the working face shall not be
more than 1.5 metres above the maximum reach of the equipment.
No undercutting of the working face is permitted.
When the maximum height of the excavation has been reached, the loading area and the top of the pile shall be cleared of all other vehicles. The front-end loader will approach the working face at a right angle and excavate a vertical face allowing the material to run to the toe of the stockpile.
Excavations shall not leave a concave hollow in the material. Operators are not to cut trenches or tunnels into the slope or leave any overhangs in frozen material.
No person is permitted to enter, on foot or in a vehicle, the loading area adjacent to the working face of a stockpile. Only the loader operator, who will remain in the cab of the machine at all times, may work in this area.
No loader operator or truck driver should leave the cab of their vehicle while loading is in progress. Pedestrians are not permitted anywhere within an active loading area. Warning signs and barricades are to be used at all times to protect active loading areas.
Operations on top of a stockpile or waste pile
Safe stockpile or waste pile and dump techniques vary depending on the type of material handled and the type of equipment available.
Safe dumping methods include;
· Material must be dumped back from the crest of the pile since the edge may not support a loaded haul truck
· Material should be pushed over the edge by a bulldozer or front-end loader using a berm of material to keep the equipment at a safe distance from the edge
· Loaders and bulldozers should always operate perpendicular to the top edge of the stockpile or dump
· Well-maintained berms should be placed along the edges of stockpile and dumps
The presence of a berm does not necessarily signify the edge is stable. Material may have been removed from the base of the pile or other movements of material may have occurred.
· Dumpsites shall be inspected frequently for signs of slope instability such as cracks, slumping on the slope or bulging at the toe
· Supervisors should inspect on foot, to supplement the equipment operators' constant vigilance
· Dump only in designated areas
· If in doubt, workers should contact their supervisor before dumping in any area or over the edge of a stockpile
· Trucks must not dump at the top of the pile where the toe has been removed