Ministry of Natural Resources
Human Resources Branch
Policy Subject: Working On Ice
Date of Issue: February 7, 2001
Preamble:
The Ministy of National Resources undertakes a wide variety of field operations that involve
working on ice. This statement is a consolidation of previous direction and is intended to
describe the minimum requirements for all operations.
Policy Statement:
Work, travel, and parking on frozen water bodies should be undertaken as a planned work
activity that recognizes and reasonably addresses the hazards associated with a floating ice
cover.
Before beginning work operations on a frozen water body, the overall condition of the ice
should be ascertained to ensure the ice could support the planned activity.
Where the depth of water under the ice is sufficient to allow a personal flotation device
(PFD) to be effective, a PFD should be worn and a self-extrication tool carried by the
employee.
Application and Scope:
This policy applies to all Ministry operations.
Where the Ministry has contracted with other parties to deliver services on its behalf, this
policy also applies.
Purpose:
To provide province-wide operating guidelines for Ministry field operations where work is
required on frozen water bodies. These are to be included in local on-ice operating
procedures.
To address Ministry requirements arising from of the Occupational Health and Safety Act.
Policy Subject: Working On Ice
February 7, 2001
Human Resources Branch
Ministy of National Resources
Mandatory Requirements:
Work activities over ice must include provisions for ensuring the well-being of Ministry staff.
This may include but not be limited to a check-in, check-out system; communication
arrangements; and/or a buddy system as appropriate for the work activity. This requirement
should be integrated into the local out-of-headquarters work procedures.
When an approved PFD is required to be worn, floatable vests, jackets, or suits may be used.
When the employee is not enclosed by any type of cab (i.e. vehicle cab) a naturally buoyant
PFD should be worn. If the employee is enclosed by a cab, or other like feature where a
naturally buoyant PFD may restrict emergency egress, an inflatable vest may be worn.
Ice conditions can vary on a daily basis and be influenced by temperature extremes, changing
water levels and snow loads. Local ice conditions should be determined prior to undertaking
on-ice activities. Where ice information is not available, consideration should be given to
conducting ice testing to determine ice thickness and bearing capacity. An ice testing
procedure is contained in Appendix One.
Parking of vehicles or other equipment on an ice cover approaching the minimum thickness
requirement for the load should be limited to a duration of not more than 2 hours. Longer
times may decrease the bearing capacity of the ice.
When an employee requires a PFD, a local rescue plan should be in place. The type of
anticipated local on-ice activities governs the content of the plan. Consideration must be
given in the plan for procedures designed to limit hypothermia.
Responsibilities:
Manager
Reviews work activities to determine application of this policy.
Ensures that work is organized in accordance with this policy and that
mandatory requirements have been addressed, and implemented into local
operating procedures.
Ensures that employees required to work on ice have been provided
instruction.
Policy Subject: Working On Ice
February 7, 2001
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Human Resources Branch
Ministy of National Resources
Examples of Minimum Ice Thickness:
Examples of minimum clear blue ice thickness requirements:
Person:
4 inches of ice, employees a minimum of 10 feet apart.
Snowmachines with one occupant
and an equipment trailer:
7 inches of ice, vehicles separated by a safe
operating/driving distance.
Light duty vehicles:
13 inches, vehicles separated by a safe driving distance.
The above are examples and reference should be made to the Bearing Capacity Table in
Appendix One for the recommended ice thickness for the specific activity.
Information regarding the use of ice covers for aircraft operations is available from the
Ministry Aviation Services Section.
Policy Subject: Working On Ice
February 7, 2001
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Human Resources Branch
Ministy of National Resources
Appendix One: Ice Testing Procedure:
Sampling:
Research local conditions to determine currents, springs, or other factors that may affect the
consistency of the ice.
Testing is to be conducted by at least two crewmembers out on the ice. The lead member is
to wear a safety harness attached to a polypropylene rescue rope a minimum of 3/8 inches in
diameter, 65 feet long, held by the trailing crewmember. Crewmembers are to be at least 30
feet apart.
Over unknown water or known moving water (i.e. river, area of springs, etceteras), the lead
crewmember should cut test holes every 25 feet or so. The distance may be increased over
known calm water, and decreased for known currents or eddies. If the distance between test
holes is increased, then the trailing crewmember must trail further back and be behind the
previous satisfactory test hole.
On lakes the distance between test holes may be substantially increased with the trailing
crewmember remaining well behind. Extra caution needs to be exercised along shore, as the
floating ice sheet may actually be thinner at the shore. As well, as progress is made across
the lake, sampling distances will need to be shortened as the ice thickness begins to decrease.
If any sample reveals clear blue ice of less than 4 inches thick, the crewmembers are to leave
the area immediately.
While sampling the crew should also be checking the ice for cracks and noting the snow load.
Ice Thickness:
Three types of ice may typically be encountered. 1) Clear Blue Ice, which is strongest. 2)
White or Opaque Ice is less dense and, therefore, weaker than clear blue ice. 3) Gray Ice,
which is indicative of thawing ice and water. Gray ice is not considered load-bearing ice.
Only the thickness of largest continuously frozen ice layer is to be considered in determining
the ice thickness. The maximum thickness to be used for determining bearing capacity is the
minimum thickness determined during sampling.
Ice thickness is calculated by using blue ice as the reference. Ice thickness is determined by
adding the full thickness of blue ice to half the thickness of white ice. For example: a sample
indicates 3 inches of blue ice and 8 inches of white ice. The equivalent thickness of blue ice
would be the 3 inches of blue ice plus 4 inches (half of the 8 inches of white ice) for a total of
7 inches.
Policy Subject: Working On Ice
February 7, 2001
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Human Resources Branch
Ministy of National Resources
The minimum equivalent thickness of ice is used to determine the bearing capacity of the ice.
Bearing Capacity of Ice:
Load,
tons
The bearing capacity of ice can be calculated by plotting the load (weight) to be carried by the
ice and the ice thickness on the graph below. By first plotting the ice thickness, the
maximum load capacity can be determined. Conversely, by plotting the weight to be carried
(eg. people and equipment) by the ice, the minimum ice thickness required may be
established.
Cracks in the ice can affect its bearing capacity. A wet crack indicates a shearing or fracture
of the ice through to the water below. Conversely, dry cracks have not penetrated the ice
through to the water.
Filling in with water or slush can repair dry cracks. Wet cracks are already filled with water
and can refreeze as strong as the original ice. Sampling should be conducted to determine the
depth of healing of wet cracks when they refreeze.
Policy Subject: Working On Ice
February 7, 2001
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Human Resources Branch
Ministy of National Resources
Adjustments to Bearing Capacity Because of Cracks or Absence of Blue Ice:
Single 1-inch or wider dry crack.
For this type of crack reduce the maximum load by one third. For example, plot ice
thickness, determine the maximum load capacity, then reduced the maximum load
capacity by one third.
Intersecting 1 inch or wider dry cracks:
Where this type of cracking occurs reduce the maximum load bearing capacity by two
thirds.
Single wet crack:
Reduce the maximum bearing capacity by one half.
Right angle wet cracks:
Reduce the maximum bearing capacity by three-quarters.
White Ice Only:
The maximum load should be reduced by one-half.
Policy Subject: Working On Ice
February 7, 2001
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