Cold Weather Construction: How to Stay Safe

The successful building of wind power projects in the extreme cold requires careful preparation for equipment needs and special attention for the safety of those working in the field.

Equipment and Processes

Cold temperatures often bring snow, ice, and other conditions that warrant special equipment including personal protective equipment and clothing such as gloves, facemasks, and ice/snow traction devices that attach to heavy boots. Other requirements include enclosures for trailers, heaters, winter fuels mixed with anti-gelling additives, hot water pressure washers and anti-freezing biodegradable washer fluid for washing tower sections, concrete blankets and plastic tarps for concrete placing, and enclosures for tower grouting activities.

Snow and Ice Removal: In order to move forward safely with construction, snow and ice must be cleared from the project site to create a safe walking surface for the movement of equipment and workers. Construction can proceed during the winter and with some snow or ice on the project site. If there is an ice or snowstorm, however, construction may be halted until weather conditions improve. Once the storm has ended the contractor will remove the areas of snow accumulation before proceeding with construction. When the weather forecast predicts a snow or ice storm it is a good practice to lower the crane boom so any build-up of snow or ice can be removed to ensure safe operation of the cranes. Construction team members will use rubber mallets to knock the snow or ice off the boom sections before the crane is placed into production operation.

Foundation Installation: Installing foundations in extreme cold temperatures requires additional equipment such as ground thaw and forced air heaters to make sure materials are within required temperature ranges during each step of the installation process. There are specific accommodations for mixing and placing the concrete. Portable concrete batch plants must be winterized sufficiently, which often means enclosing them in heavy plastic tarps or tents. The sand and aggregate must also be heated and mixed with hot water to correctly prepare the concrete.

Additionally, foundation rebar must be warmed to required temperature ranges before concrete can be placed around it. Under specific conditions the concrete must be secured under supplemental heat. Construction crews will use extra heaters and heavy insulated concrete blankets to ensure that the foundations are cured even in very cold temperatures. This type of planning also affects the placement of grout around the foundation pedestal.

Hazards and Concerns

Working in extremely cold temperatures can lead to dangerous conditions, the most significant of which are frostbite and hypothermia. Several factors contribute to the risk of injury including: temperature, wind speed, moisture (sweat or working near water), duration of exposure, clothing, work/rest schedule, work performed, and other individual characteristics.

Frostbite is the actual freezing of tissue. Exposed skin becomes vulnerable to frostbite when the air temperature drops below 0° C/32°. If skin is not protected, frostbite can lead to body tissue damage. Symptoms of frostbite vary from swelling and red coloration of the exposed area and slight pain in mild cases to extreme tissue damage with black/dark bluish-purple in severe cases. Depending on the level of exposure frostbite can occur with little or no pain or cause a burning/prickling sensation in more severe cases. If minor exposure has occurred the affected areas of the skin should be warmed slowly until normal temperatures are reached. When higher levels of exposure occur, medical attention should be initiated.

Hypothermia occurs when the body core temperature drops below 35° C/95° F. Once this happens the body loses its ability to prevent heat loss and is losing heat more quickly than it can create heat. Hypothermia is typically a gradual process, with the exception of extreme exposure such as falling through the ice on a frozen lake. As hypothermia develops the victim initially has a sensation of cold followed by pain. As time passes the level of pain increases and the body becomes numb. Symptoms of hypothermia include a decrease or absence of shivering, reduced memory and confusion, drowsiness, slurred speech, impaired coordination, a loss of dexterity, and general muscular weakness. In cases of minor hypothermia the exposed individual should be covered with heated blankets. If not identified and addressed quickly, hypothermia can lead to death. Extreme cases of hypothermia require immediate medical care from experienced medical personnel as quickly as possible.

Preparing Workers

The Layered Approach to Clothing: When selecting proper cold weather clothing a layered approach is best. Too little clothing leaves the worker exposed to the cold. Too much clothing leads to sweat, wetness, and cold, which then can lead to hypothermia. Workers must wear the appropriate amount of clothing to keep their heat loss to heat production rate neutral. When layering clothing it is best to select a windproof outer layer that is at least water resistant, but ideally waterproof. . Since toes, fingers, ears, and other parts of the face are at risk of frostbite, footwear, gloves/mittens, and face protection must be used to protect the worker, taking into consideration the ability to perform the various tasks on a wind power project during construction.

Warm-up Breaks: Workers who are outside for extended periods in cold environments should take regular warm-up breaks, preferably inside a warm shelter or heated vehicle. Warm-up breaks should still be mandatory, even when appropriate winter clothing is selected and utilized effectively. If excessive sweating does occur during the warm-up break, the individual should change into dry clothing prior to reinitiating work activities.

Individual Factors: Various factors may contribute to an individual’s ability to withstand working in cold conditions. Factors such as age, physical health, acclimatization to cold, etc., can all determine the exposure time of worker in cold temperature environment.

Preparing and Prioritizing

Extreme temperatures, hot or cold, bring many necessities for building safely and within given timeframes. Extreme heat is no less dangerous than extreme cold, and preparing adequately for these temperatures is a must for worker safety and best use of equipment. The good news is that an experienced EPC contractor can typically plan for extreme temperatures in the peak winter and summer months. A prepared contractor will budget for and pre-order the proper protective gear and equipment to ensure that construction runs smoothly and safely even in extreme weather.

About the author: Trent Schon is director of safety for Mortenson Construction’s Renewable Energy Groups and a board-certified safety professional.