Construction sites and excavations can generate a wide variety of environmental hazards that put contractors’ teams at risk. Both known and unknown underground conditions may generate environmental hazards to construction crews when excavating. This article provides examples of the multitude of environmental hazards faced when excavating and discusses best practices to control the environmental risks of working in excavations and avoid injury.
Underground utilities are frequently encountered during excavations, whether they are expected or not. Underground gas lines are particularly dangerous for a variety of reasons. The natural gas inside these pipes is highly flammable and potentially explosive under the right conditions. A stray swing of an excavator bucket can puncture or sever a gas line generating a flammable and explosive hazard, especially if rock is in the area, which may increase the risk of generating a flame-igniting spark if struck by metal equipment. Additionally, packaging from construction materials may include paper and cardboard that is easily flammable.
Explosions and fires can be avoided with a cleanly run site. First, superintendents should provide clear trash areas for construction waste such as packaging and pallets as well as garbage generated from workers such as food wrappers. Next, superintendents should designate smoking areas away from excavations and from standard trash areas; something as simple as a 5-gallon bucket with sand can be an appropriate cigarette butt container that mitigates the risk of lit cigarettes starting fires. Do not burn trash or other refuse on job sites. Finally, excavators should understand what utilities are known to be underground in the excavation area but still operate as if a hazardous utility could be uncovered at any time. This means excavating deliberately without cutting more than is necessary to complete the job and stopping excavation if a utility is uncovered. Also, “hot work” such as welding should be avoided near garbage or gas lines where possible.
Toxic/Contamination/Ambient Chemical Vapors
A variety of toxins may be present in the soil when excavating near biologically and chemically dangerous sites such as landfills, underground chemical storage tanks, refineries, and treatment plants. Construction equipment and generators may also emit fumes that can be harmful if inhaled. There is no shortage of potentially harmful liquids and vapors on excavation sites and all safety precautions should be taken to control the risk of toxicity, contamination, and other related injuries.
If an unknown chemical is discovered during an excavation, it is safest to assume that it is toxic and life-threatening. Immediately cease all excavations and notify the proper authorities to secure the site and allow for appropriate cleanup and decontamination measures. Do no use spark-producing equipment near the chemical, do not smoke near the chemical, and move personnel upwind to avoid breathing in potentially harmful fumes. Similarly, avoid congregating near vehicle exhausts to reduce the inhalation of harmful fumes. For known chemicals used on-site, follow all safety instructions according to the Safety Data Sheet for the chemical. This may include wearing gloves and safety glasses, providing secondary containment to avoid spill contamination, and providing proper ventilation for fume-producing chemicals. Chemical monitoring equipment may be appropriate for excavations where toxic conditions are possible.
Dust and other suspended particles in the air can introduce job site hazards that may lead to injury. On dryer sites, vehicular and equipment traffic can easily kick up enough dust to cause visibility issues and make breathing difficult. High winds may also suspend soil particles, particularly in more arid regions with wide expanses of open space. While the hazards caused by dust and suspended particles can be controlled and mitigated, it is difficult to eliminate the risk because both the weather and people not working on the job site can have an impact on the amount of dust in the air. Silica in particular is dangerous when inhaled, as it is more likely to cause severe respiratory illnesses. Silica is mostly present in sands and concrete dust.
Superintendents should strive to minimize the amount of traffic on dry, disturbed soil to minimize soil suspension. A site speed limit can also be implemented to ensure workers do not unintentionally produce a potentially harmful dust cloud. Most erosion control plans call for temporary seeding in areas where soil will be exposed for more than fifteen days. Finally, running a water truck is a powerful tool to reduce dust by keeping lighter soil particles grounded with water. A good rainstorm on an off-work day can also be a blessing to contractors working in dusty environments. Where dusty conditions can not be avoided, superintendents should issue PPE to workers such as respirators, masks, and goggles, particularly to workers that don’t have the luxury of a cabbed vehicle. Additionally, drastically reducing speeds or calling off work completely may be appropriate depending on the severity of the dust clouds.
Water can be a dangerous hazard on excavation sites that can generate a variety of risks if not properly controlled. Drowning is a significant risk that can occur with as little as a puddle of water. The risk of electrical shock increases if electrical work is required on wet excavation sites. Slips, trips, and falls are exacerbated by standing water and the mud left behind. Hypothermia also becomes a concern in colder environments. Water also invites pests and wildlife to the site that may generate a risk of injury and/or illness to workers.
Earthwork contractors can mitigate the risk of most water hazards by ensuring positive drainage throughout the site even before final grading. This will mitigate the risk of stormwater runoff ponding on-site and generating many of the risks noted above. Cold environments may still introduce risks like hypothermia and frostbite, but removing water from the site significantly reduces these risks. Additionally, for pit excavations, contractors should utilize pumps to de-water the pit and further mitigate the risk of drowning and other waterborne injuries.
Excavations produce a bevy of risks that require deft control of the earthwork site to mitigate injury. Explosions and fires, chemical inhalation and contamination, dust inhalation and reduced visibility, and water hazards are among the risks site supervisors must control. By understanding the environmental hazards present in excavations, superintendents can provide a safe working environment for their laborers, operators, and tradespeople.