Introduction
Building tunnels, shafts, and passages beneath the surface is a game of risk and reward. Low light, restricted entry and exit points, and a real risk of exposure to bad air and fire hazards make the job an underground construction worker as exciting as it is perilous. To shield those hearty souls who do this work, the Occupational Safety and Health Administration (OSHA) has created some handy guidance material. This includes the underground construction regulations tucked away in Title 29 of the Code of Federal Regulations, Part 1926, section 800 (29 CFR 1926.800). First penned in 1971, these regulations have been tweaked over time to bolster safety measures for these workers. This piece of writing shines a light on those regulations, but remember, it’s a summary, not a full recount of 29 CFR 1926.800.
Construction Operations Covered by the OSHA Standard
The rules in OSHA’s underground construction regulations apply to the creation of all things subterranean – tunnels, shafts, chambers, and passages. It also has something to say about cut-and-cover excavations that are tied to ongoing underground work and those which give rise to the same conditions as underground work. Dim lighting, limited entry and exit, harmful air contaminants, fire risks, flooding, and the threat of explosions – all are covered by the regulation. However, the rulebook doesn’t touch on excavations for above-ground structures that aren’t connected to underground work or electrical lines underground.
In the world of underground construction, OSHA offers these definitions:
A “tunnel” is any dig beneath the surface where the longest axis doesn’t veer more than 20 degrees from horizontal. A “shaft” is either a passage from surface to underground following an axis at an angle of more than 20 degrees from horizontal, a pit where workers may need to enter, or a pit featuring typical underground hazards and connected to a horizontal dig.
Employers and Employees Covered by the OSHA Standard
Generally speaking, OSHA has the right to oversee all private sector employers with one or more employees, as well as civilian workers in federal agencies. This means employers and employees in construction are under their umbrella. However, self-employed individuals, public workers at state and local level, workers regulated by other federal agencies (like mine workers and atomic energy workers), and family members working on farms without external employees are out of OSHA’s remit.
States can run their own safety and health programs if they’re approved by the Department of Labor under the Occupational Safety and Health Act of 1970, section 18(b), but the standards must meet or exceed federal requirements. In 2003, 26 states were running their own safety and health programs. Most of these states covered both private and public workers, though three catered only to public sector employees. The safety and health standards in these states have to match or outdo federal OSHA standards.
Requirements of the OSHA Standard
The underground construction standard covers a whole host of concerns for those brave souls working under the surface. It includes safe routes in and out, employee training in hazard recognition, a “check-in/check-out” system, and emergency plans. This booklet is your shortcut to all the standard’s requirements. The standard offers some wiggle room in how to handle hazards in underground construction, as long as it doesn’t compromise worker safety. A “competent person” is required to execute several elements of the underground construction regulations, which we’ll touch on later.
The Need for a “Competent Person”
The term “competent person” as defined in 29 CFR 1926.32 (f) refers to someone who can spot hazards in the environment or working conditions that are unhygienic, hazardous, or dangerous to employees and has the authority to take quick action to rectify them. In the realm of underground construction, this competent individual is tasked with inspecting and evaluating conditions at the workplace, which include air monitoring, presence of air contaminants, stability of the ground, and the drilling, hauling, and hoisting of equipment, to identify and correct any deficiencies.
Training Requirements
All employees engaged in underground construction should be trained to identify and respond to the specific risks associated with this line of work. Training should be geared to the unique demands of the job site and cover any special issues or needs.
Notification and Communication Requirements
Any time an employer is notified of a hazardous condition, all incoming shifts must be made aware of situations or conditions that could affect their safety. This includes equipment failures, earth or rockslides, cave-ins, flooding, fires, explosions, or release of gas. The employer also has to keep communication open with other employers at the work site to ensure a swift and comprehensive exchange of information regarding events or situations that may impact worker safety.
Communication is also crucial between employers and employees during underground construction work. Communication systems should be tested at the start of each shift and as often as necessary afterward to ensure they’re functional. Any communication system should operate on an independent power supply, and it should be installed such that the disruption of any single device or signal location doesn’t interfere with the system’s operation elsewhere.
Keeping Track: Checking In, Checking Out
Now, it’s a fundamental requirement, but also just plain common sense, to keep an accurate headcount of who’s under and who’s topside. This is done through a check-in/check-out system that is managed by our folks up top. This way, we ensure that unauthorized folks don’t sneak in and we know who’s where if things go south. The only time we don’t need this is when we’ve got a fully finished underground construction project with effective permanent environmental controls and any remaining work isn’t going to stir up hazards or structural failures. We also need to have one designated person always topside whenever we have workers underground. This person has the important task of getting help pronto and keeping track of everyone below in an emergency.
Access and Egress: Control of Entry and Exit
In addition to our check-in/check-out system, we need to make sure that everyone can safely get in and out of all workstations to protect them from accidents involving moving equipment like excavators or haulage machines. We keep control of access by making sure all unused openings are securely covered, bulkheaded, barricaded, or fenced off, and are adorned with a bright, bold “Keep Out” sign, or something similar.
Supporting Portals and Subsidence Areas
It’s critical to keep portal openings and access areas secure with protective measures like shoring, fencing, head walls, shotcreting, or something equivalent, to make sure our people and equipment can safely get in and out. Subsidence areas need the same treatment – we protect them by shoring, filling them in, or putting up barricades and warning signs to keep folks out. We also have to make sure nearby areas are secure to stop loose soil, rocks, or fractured materials from jeopardizing portal, subsidence, and access areas.
Ground Support in Underground Areas
We need a competent person on the job to inspect the roof, face, and walls of work areas at the beginning of every shift and as often as necessary after that, to make sure we’ve got stable ground. This person needs to be protected from loose ground by location, ground support, or another suitable method. We also need to keep a close eye on the ground conditions along all haulage ways and travel ways to ensure safe passage. Any loose ground that could be a risk to workers must be scaled, supported, or taken down. It’s up to our competent person to determine how often rock bolts need to be tested to ensure they’re up to snuff, considering ground conditions, distance from vibration sources, and the specific bolt system in use. When it comes to ground support, we can only trust torque wrenches for torsion-dependent bolts.
Supporting the Grounds of Shafts
Any shafts and wells that are over 5 feet deep and have workers going in and out need to be supported by steel casing, concrete pipe, timber, solid rock, or something else that can do the job. The full depth of the shaft needs to be supported unless it’s going into solid rock that’s not going to change with exposure.
Fire Prevention and Control
Underground construction areas come with their own set of rules when it comes to preventing and controlling fires. No open flames or fires are allowed unless they’re needed for welding, cutting, or other hot work operations. Smoking is a no-go unless the area is free of fire and explosion risks. Signs reminding folks of these rules should be posted all over the place. Fire extinguishers need to be ready to go at the head and tail pulleys of underground belt conveyers.
Diesel Fuel Usage in Underground Construction
When it comes to using diesel fuel in underground construction operations, there are a few specific rules to follow. A surface-level tank holding diesel fuel for pumping to an underground storage site can’t hold more than a day’s worth of fuel for underground equipment. The tank needs to be connected to the underground fueling station by a safe pipe or hose system controlled by a valve at the surface and a hose nozzle at the bottom. The transfer pipe should always be empty unless it’s being used to transfer diesel fuel. Any hoisting operations in the shaft must be stopped during refueling operations if the supply piping in the shaft isn’t protected from potential damage.
Ventilation Necessities
A Breath of Fresh Air
Let’s face it, working underground means breathing in all kinds of stuff. Dust, fumes, mists, vapors, and gases – none of it exactly pleasant, some of it downright harmful. To avoid it all, we need fresh air pumped in, and plenty of it. If Mother Nature isn’t doing her part, it’s on us to make sure every worker gets a good gulp of fresh air, about 200 cubic feet a minute.
When the Dust Flies
Things get a bit trickier when we’re stirring up all sorts of stuff. Blasting, rock drilling – these are dusty jobs, no two ways about it. So, we’ve got to get the air moving in those tunnel bores, shafts, and workspaces, at least 30 feet a minute, so we can clear out all that nasty stuff. When the job’s done, we’ve got to make sure the smoke and fumes are escorted right out into the open air before anyone can get back to work.
Dust Control Measures
Now, drilling into rock or concrete is like turning on a dust storm. The best way to keep dust from getting out of hand is to fight it at the source: use wet drilling, vacuum collectors, or water mix spray systems. It’s not just the dust we’re worried about, it’s all sorts of air nuisances, like gases, vapors, fumes, and mists. We’ve got to keep these within the limits set by the folks at OSHA.
Mechanical Airflow and Ventilation Doors
In our underground world, we’ve got to be flexible. That’s why our mechanical airflow has to be reversible. But, we also need to keep our ventilation doors securely shut, regardless of which way the air is flowing.
Ventilation System Shutdowns
If we have to shut down the ventilation system and evacuate everyone, it’s up to our most competent folks to first brave the underground. They’ve got to make sure the air down there is safe before anyone else can head back in.
Illumination Requirements
To ensure optimal working conditions and safety, adequate lighting is essential in our underground operations. It’s not merely about visibility; proper illumination is a pivotal aspect of identifying potential hazards, performing tasks efficiently, and preventing accidents. As per OSHA guidelines, different work areas necessitate varying minimum illumination levels. For general construction areas, the minimum illumination required is 5 foot-candles. For underground tunnels, shafts, and general excavation work, the required minimum is 5 foot-candles. Workplaces where machinery such as drills or conveyors are in operation demand a minimum of 10 foot-candles, while areas where workers perform tasks like reading or other near work, 30 foot-candles are mandatory. Each worksite should ensure these illumination standards are met, fostering a safe and effective work environment.
Air Monitoring Duties
On the Lookout for Bad Air
We need a sharp individual to keep an eye on the air quality. If they smell trouble – if there’s a risk to life from air contaminants – it’s their job to raise the alarm. We’ve got to take precautions and let everyone know what’s going on. The air monitor takes all sorts of things into account, like where the jobsite is, what’s happening around it, what’s happened there before, and how people are working.
Testing for Oxygen and Other Harmful Substances
Before we start worrying about other potential air contaminants, we need to ensure there’s enough of the good stuff – oxygen. OSHA standards mandate that oxygen levels must be maintained between 19.5% and 23.5% to ensure a safe working environment. We must conduct frequent checks and uphold these levels within the acceptable limits.
Once the oxygen is in check, it’s time to scan for things we don’t want – harmful substances like carbon monoxide, nitrogen dioxide, hydrogen sulfide, and others. As per OSHA standards, permissible exposure limits (PELs) have been set for these harmful substances. For instance, the PEL for carbon monoxide is 50 parts per million (ppm) over an 8-hour work shift, for nitrogen dioxide it is 5 ppm over an 8-hour work shift, and for hydrogen sulfide, it’s 20 ppm over an 8-hour shift. These limits for toxic gases, dusts, vapors, mists, and fumes must be strictly adhered to for worker safety.
Testing for Methane and Flammable Gases
And let’s not forget methane and other flammable gases. We’ve got to know if we’re dealing with a gassy or potentially gassy situation and act accordingly. There are extra precautions to take when we’re dealing with flammable gases, including specific limits that trigger evacuations, work suspensions, and increased ventilation measures.
Hydrogen Sulfide Levels
If we pick up 5 ppm or more of hydrogen sulfide, it means constant testing until we get three days in a row under that limit. If the levels get too high, it’s time for alarms, respirators, or even evacuations.
Drilling and Blasting Underground
Before You Drill
Before we even think about starting a drill, we need someone who knows what they’re doing to check everything over – the drill, the gear, the area, everything. And while the drill bit’s turning or the drill’s being moved, nobody’s allowed on the drill mast.
Working with Jumbo Decks
Jumbo decks need special handling. We’ve got to take precautions when working on or around them, like making sure everything is securely stored and warning anyone working below when drilling’s about to start. And of course, the jumbo needs to be steady and secure whenever anyone’s working on it.
After Blasting
When the dust settles after blasting, we need to check the air and make sure everything is still in one piece. If any repairs are needed, only the repair crew should be in or below the affected area. And we’ve got to make sure blasting wires are kept clear to avoid any nasty surprises.
Cranes and Hoists Underground
Cranes and hoists might be common tools, but they need special handling underground. The hoist operator must be able to see and hear signals at the operator’s station. All cages must be equipped with a steel-plate protective canopy that slopes to the outside and can be pushed up for emergency egress and have a locking door that opens only inward. The sides of personnel cages must be enclosed by 1/2 inch wire mesh to a height of at least 6 feet (1.83 m). If the cage is being used as a work platform and is not in motion, the sides may be reduced to 42 inches (1.07 m). During sinking operations in shafts where guides and safeties are not used, the personnel platform may not exceed 200 feet (60.96 m) per minute and governors must be used during personnel hoisting. The speed may increase to 600 feet (182.88 m) per minute when guides and safeties are used and greater speeds when shafts are complete.
Hazards That Warrant Extra Caution
Gassy or Potentially Gassy Situations
Unearthing dangerous gases can lead to some serious threats down in the pits. Now, these dangers often hinge on two buzzwords – “gassy” and “potentially gassy.” And trust me, knowing the difference between the two can save lives. In these risky areas, you need special gear like fire-resistant ventilation systems, electrical systems that play nice with fan motors, and above ground controls for changing the air direction.
Also, if you’re using a mine-style ventilation system with a fan on the surface, make sure it’s got blast doors or a frail wall – with a similar cross-sectional area to the airway – to take the brunt of an explosion.
So, when are things considered gassy? Well, you’re in a gassy area when air testing reveals methane or other flammable gases are 10% or more of the lower explosive limit. Or, if there’s been an ignition of these gases or your operation connects to another gassy zone, then, my friend, you’ve got a gassy operation on your hands.
There are several rules to follow when dealing with these zones, touching on both gear and personnel safety. Some highlights include clearly marking gassy operation entrances, enforcing a strict no-smoking rule (and nabbing any sources of ignition from folks entering), and using only the highest quality, well-maintained gear. Any mobile diesel-powered equipment should be either approved by MSHA, or proven to be its equal.
If a site has been labeled as gassy, you’ve got to hit the brakes on all operations there until everything complies with safety requirements. The only exceptions here are actions to control the gas concentration, installing above ground gear to change airflow direction, or moves to comply with gassy operation safety standards.
Things can cool down to “potentially gassy” status when gas tests show less than 10% of the lower explosive limit for three straight days.
Potentially Gassy Operations
These operations are a bit different – they might stumble upon a gas pocket unexpectedly. We label operations as potentially gassy when air tests show 10% or more of the lower explosive limit for flammable gases for more than 24 hours. This can also be the case if we expect such gases based on the area’s history, the geological formation, or past experiences.
Both gassy and potentially gassy operations need to stay on their toes when it comes to air monitoring, under the supervision of a knowledgeable individual. This involves checking oxygen levels and flammable gas content in affected work zones and nearby areas at the start and middle of each work shift.
During rapid excavation, you’ve got to keep a continuous, automatic flammable gas monitor going, keeping tabs on the air at the heading, on the rib, and in the return air duct. If you hit 20% or more of the lower explosive limit for flammable gases, the continuous monitor alarm should warn everyone and cut power to the affected zone (pumping and ventilation gear is the exception).
For jobs involving welding, cutting, or other hot work, local gas tests are a must both before and during the job. And for drill-and-blast operations, the air in the affected area should be continually tested for flammable gas when folks are working in the area and before reentering after blasting.
Emergency Measures
Whenever there’s someone working underground, someone else should be topside, keeping tabs on the headcount below and ready to summon help if needed. All underground workers need a portable lamp for emergencies, unless there’s enough natural light or an emergency lighting system in place.
If there’s a chance workers might be trapped by smoke or gas, employers have to provide self-rescuers approved by NIOSH. If you’ve got 25 or more folks underground at once, there should be at least two 5-person rescue teams on standby – one nearby or within half an hour of the entry point, and the other within two hours’ travel time.
For fewer than 25 workers, one 5-person team should suffice. In both cases, it’s okay to arrange for local rescue services to meet this requirement. Rescue team members should be trained in rescue procedures, know how to use and the limits of breathing gear, and be proficient with firefighting equipment, with their qualifications reviewed yearly.
Rescue teams should also practice using self-contained breathing apparatus every month if dangerous gases are expected at a site. And don’t forget, these teams should be available for the whole duration of a construction project. If a shaft is used for exiting, there should be a readily available power-assisted hoisting capability for emergencies unless the regular hoisting means will still work during a power outage.
Keeping Track of Data
Keep records of all air tests above ground at the site, available on request to the Secretary of Labor or their representative. This should include details like location, date, time, and the substance and amount tested. For toxic substance exposure records, keep them for 30 years.
For all other air quality test records, keep them until the project’s completion. Inspection certification records for all hoist gear – indicating the most recent inspection and load-test date, the person who did the inspection and test, and a serial number or identifier for the hoist – should be kept until the project’s done.
Conclusion
Balancing safety with productivity in construction is a challenging task, and this is where the value of the OSHA standards truly shines. By incorporating their comprehensive guidelines, ranging from ground support to illumination, ventilation and gas testing, businesses ensure a safe, efficient work environment.
The OSHA standard not only mitigates immediate risks in gassy or potentially gassy operations, but also prepares companies for the unexpected through well-defined emergency procedures. Moreover, stringent record-keeping requirements serve as a constant reference, further enhancing safety and operational standards. At the end of the day, these standards aren’t just about compliance – they’re instrumental in promoting a safety-first culture in construction, facilitating an environment where workers can focus on their tasks knowing that their wellbeing is a priority.
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