OSHA Underground Construction: Safety Standards and Solutions

In 2022, 39 workers lost their lives due to trench or excavation incidents in the U.S., more than doubling the number from 2021. The dangers of underground construction are evident from this data, and while technology has evolved to decrease the likelihood of underground construction accidents, prioritizing safety standards remains as crucial as ever. 

An underground pipeline construction worker once told me that he felt that accidents that occur underground are far more dangerous than those above ground. “Nobody can see what we’re doing down here but us,” he said, emphasizing that employee safety standards have to be strictly enforced due to the limited visibility.

The Occupational Safety and Health Administration (OSHA) sets and enforces safety standards to minimize risks related to cave-ins, hazardous atmospheres, equipment malfunctions, and other underground construction dangers. In this article, I will discuss the fundamentals of underground construction safety as laid down by OSHA and how you can comply with these regulations.

Key Takeaways 

• Securing the appropriate construction licenses for underground work ensures regulatory compliance and demonstrates your commitment to meeting industry safety standards.

• Effective underground construction safety protocols save lives by addressing unique hazards including oxygen-deficient atmospheres, ground instability, and confined space dangers.

• Proper training and certification are non-negotiable elements of underground safety, ensuring workers can identify risks and respond appropriately to emergency situations.

• Regular inspections and monitoring of air quality, structural integrity, and electrical systems prevent catastrophic incidents in underground environments where evacuation is challenging.

What Is Underground Construction?

Underground construction refers to the process of building structures beneath the earth’s surface. It includes the excavation, reinforcement, and development of underground tunnels, subways, mines, pipelines, and other subterranean infrastructure. This type of construction is essential for transportation, utilities, storage, and urban development.

Examples of Underground Construction

• Water Supply Systems – Water supply systems are underground pipeline constructions (as shown in the image above) and reservoirs that transport and store clean water for residential, commercial, and industrial use.

• Gas Pipelines – Subsurface pipelines that transport natural gas and other fuels safely over long distances to homes, industries, and power plants.

• Electrical Power Cables – Underground high-voltage cables that distribute electricity while reducing exposure to weather-related damage and power outages.

• Telecommunication Lines – Telecommunication lines are fiber optic and copper cables that are placed underground to ensure reliable internet, phone, and data communication services.

• Transportation Tunnels – Transportation tunnels are underground passages for trains, subways, and road vehicles, helping reduce traffic congestion and improve urban mobility.

• Utility Underground Tunnels – Utility tunnels are enclosed underground corridors that provide a centralized location for utilities, making maintenance, repairs, and upgrades more efficient while minimizing disruptions to surface activities. 

• Stormwater Management Systems – Stormwater systems are underground drainage tunnels and reservoirs designed to control water runoff, reduce flooding, and protect urban areas from storm damage.

What Are the Risks of Underground Construction?

I once spoke with an underground utilities construction worker who was in charge of operating a tunnel-boring machine. He shared that he developed silicosis, a lung disease caused by long-term exposure to silica dust in underground environments. Apart from respiratory diseases, underground construction workers also face the following risks:

• Engulfment – This is the risk of being trapped by collapsing soil, water, or loose materials in confined underground spaces.

• Noise – High levels of noise from drilling, machinery, and excavation, which can lead to hearing loss and other health issues.

• Fire and Explosion – This is the presence of flammable gases, electrical sparks, or combustible materials underground can increase the likelihood of fires and explosions.

• Electrical Hazards – Working in wet underground conditions with electrical equipment creates heightened risks of electrocution. Water accumulation, damaged cables, and improper grounding in confined spaces can make electrical accidents particularly dangerous.

• Ground Instability – This is the risk of ground movement, tunnel cave-ins, or structural failures due to geological conditions, inadequate support systems, or vibration from construction activities. This includes risks from rock falls, unstable soil conditions, and settlement of surrounding structures.

• Toxic and Oxygen-Deficient Atmospheres – Underground workspaces can accumulate hazardous gases like methane, carbon monoxide, and hydrogen sulfide, leading to suffocation or poisoning if not properly ventilated.

• Psychological Risks – The construction of underground infrastructure also poses risks including claustrophobia, anxiety due to the lack of natural light, and depression due to the isolation.
  
  

What Are Underground Construction Regulations?

Underground construction regulations address various hazards associated with underground construction, including reduced natural ventilation and light, difficult access and egress, exposure to air contaminants, and risks of fire, flooding, and explosion. While there are several regulatory bodies for underground workplaces, OSHA lays down the main safety components in its regulations.

OSHA Regulations

OSHA has established comprehensive regulations to ensure safety in underground construction, as detailed in 29 CFR 1926.800 and further elaborated in OSHA's publication OSHA 3115. These standards apply to the construction of underground tunnels, shafts, chambers, and passageways, as well as cut-and-cover excavations connected to ongoing underground operations. 

Air Monitoring and Ventilation

OSHA mandates continuous monitoring of air quality in underground workspaces to detect hazardous gases and ensure sufficient oxygen levels. Employers must implement ventilation systems capable of maintaining air quality within safe limits, thereby protecting workers from respiratory hazards. 

Illumination Requirements

Adequate lighting is essential in underground construction to ensure visibility and prevent accidents, especially in deep underground tunnels. OSHA specifies minimum illumination levels for different work areas, requiring employers to provide and maintain sufficient lighting equipment to meet these standards. 

Fire Prevention and Control

Given the confined nature of underground construction activities, fire hazards pose significant risks. OSHA requires the development and implementation of fire prevention programs, including the availability of firefighting equipment, regular fire hazard assessments, and employee training on emergency response procedures. 

Ground Support and Structural Integrity

To prevent collapses and ensure the stability of underground structures, OSHA mandates the use of appropriate ground support systems. Employers are responsible for designing, installing, and maintaining supports such as side support walls, shoring, bracing, or rock bolts, based on geological assessments and engineering principles. 

Site Control Procedures

OSHA mandates the implementation of effective site control measures to manage access to underground areas. This includes securing all openings to prevent unauthorized entry and ensuring that unused or completed sections are properly barricaded or covered. Such measures are crucial to protect both workers and the public from potential hazards associated with underground worksites.

Check-in/Check-out Procedures

To maintain an accurate account of personnel underground, employers are required to establish a reliable check-in/check-out system. This system ensures that, in the event of an emergency, above-ground personnel can quickly determine the number of individuals underground and initiate appropriate rescue operations. Maintaining precise records of all entries and exits is essential for effective emergency response and overall site safety.

Communication Requirements

Communication systems must be tested from the entry point to the underground location when first installed. Each system requires an independent power supply and must be configured so that individual device issues don't affect the whole network. Regular testing is required to ensure all communication lines remain operational throughout construction activities.

Competent Person Designation

OSHA requires the designation of a "competent person" who is capable of identifying existing and potential hazards in the surroundings and has the authority to take prompt corrective measures. This individual is responsible for conducting regular site inspections, overseeing safety protocols, and ensuring compliance with OSHA standards.

Emergency Procedures and Evacuation Plans

Employers must establish comprehensive emergency response plans tailored to underground construction scenarios. This includes providing emergency escape routes, conducting regular evacuation drills, and ensuring the availability of rescue equipment to facilitate prompt and effective responses to emergencies.

Other Regulations

• Mine Safety and Health Administration (MSHA) Regulations - MSHA regulations govern all underground safety operations, including ventilation standards, ground control plans, emergency protocols, equipment safety, worker training, and exposure limits for dust and noise.

• Environmental Protection Agency Regulations - These guidelines manage environmental impacts through groundwater protection, excavation material handling, erosion control, stormwater management, emissions control, and contaminated soil disposal protocols.

• National Electrical Safety Code - This code establishes requirements for underground electrical installations, covering equipment grounding, cable spacing, and protection, waterproofing standards, emergency power systems, and lighting requirements.

• State and Local Building Codes - These codes address jurisdiction-specific structural requirements including concrete strength, waterproofing, fire protection, emergency egress, ventilation standards, and geotechnical specifications for soil stability.

Emergency Procedures and Evacuation Plans

OSHA also includes a comprehensive emergency plan as one of its key components in its underground construction regulations.  The emergency plan delineates emergency exits or escape routes, the conducting of regular evacuation drills, and the availability of rescue equipment to facilitate prompt operations and effective emergency responses. The plan must also address these risks:

1. Fire

2. Flooding

3. Gas/hazardous fume release

4. Power failure

5. Cave-ins or ground failure

6. Medical emergencies

An effective emergency plan requires the following equipment on site:

• Self-rescuer devices

• Fire extinguishers

• First aid supplies

• Communication systems

• Emergency lighting

The emergency plan may also include a designated person to keep track of the workers underground and maintain communication with them, especially during emergencies and evacuations. This designated person in this operation may or may not be what OSHA defines as a competent person.

Who Is a Competent Person?

According to OSHA, a competent person is someone who is capable of identifying existing and potential hazards in the workplace and has the authority to take corrective actions to eliminate or control them. This individual must have both knowledge and experience related to the job and must be designated by the employer.

Main Responsibilities of a Competent Person

A competent person in underground construction is responsible for ensuring workplace safety and compliance with OSHA regulations. Their key duties include:

• Conducting Hazard Assessments – Identifying potential risks in operations such as cave-ins, toxic gases, flooding, or equipment failures.

• Inspecting Work Areas – Performing regular safety checks on trenches, underground tunnels, and shafts to ensure compliance with OSHA standards.

• Ensuring Proper Protective Systems – Verifying the use of trench boxes, shoring, and other protective measures to prevent collapses.

• Monitoring Air Quality – Checking for hazardous gases and ensuring proper ventilation in confined spaces.

• Supervising Excavation and Shoring Procedures – Ensuring that soil stability and reinforcement systems meet safety standards in operations.

• Providing Safety Training – Educating workers on hazard recognition, emergency procedures, and the proper use of protective equipment.

• Implementing Emergency Procedures – Preparing for incidents such as cave-ins, fires, or equipment malfunctions and ensuring workers know how to respond.

• Enforcing PPE Use – Ensuring workers wear helmets, respiratory protection, gloves, and other safety gear as required.

• Stopping Unsafe Work – Having the authority to halt operations if hazardous conditions are detected until corrective measures are in place.

Construction Methods for Underground Safety

The selection of appropriate underground construction methods is critical to worker safety, project success, and public protection. Different methods present unique safety considerations:

• Cut and Cover Method: A trench is excavated, and the tunnel structure, including the tunnel roof, is built before being covered again. This technique is commonly used for shallow tunnels.

• Top-Down Method: Tunnel structures are constructed from the surface downward, ensuring ground stability while excavation proceeds.

• Pipe Jacking: A method that pushes prefabricated tunnel sections through the ground with hydraulic force, used for utility and drainage tunnels.

Underground Construction Safety Solutions

A worker once described to me his first time walking into a dimly lit, deep tunnel and seeing workers operating heavy machinery in confined spaces, dealing with groundwater seepage, and managing complex ventilation systems. That experience showed him why comprehensive safety solutions are essential in underground facilities. Here are the key components of an effective underground construction safety program:

• Safety and Health Programs - Comprehensive workplace safety initiatives that include risk assessments, hazard prevention protocols, emergency response plans, and ongoing safety monitoring systems.

• Training and Outreach Services - Educational programs providing workers with required certifications, safety procedures, equipment operation training, and regular updates on industry best practices and regulations.

• Safety and Health Topics - Detailed coverage of specific underground construction hazards including air quality, ground support, employee exposure, electrical safety, confined spaces, and proper use of personal protective equipment.

• Consultation Services - Professional guidance and evaluation of existing safety programs, compliance audits, site-specific risk assessments, and recommendations for safety improvements and regulatory compliance.

When Do You Need a License for Underground Construction?

The question of when to secure a license for underground work is commonly asked in online forums. People are sharing their experiences and advice on acquiring the appropriate license for underground work, especially regarding state-specific requirements. One Reddit user even shared:

Yard4111992 commented on post

In Florida, a GC cannot pull permits for underground utilities. An Underground Utilities and Excavation license is required (Certified Utility & Excavation Contractor- CUC).

Some municipalities will allow a GC to pull the permit because they are not familiar with the state licensing requirements. It is illegal to pull permits for unlicensed contractors.

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To help others avoid similar pitfalls, here are the general instances when you'll need a license for underground construction:

• Excavation and Trenching

• Structural Work (Tunnel Construction, Shaft Construction, and Bunkers)

• Plumbing, Electrical, or Gas Work

• Septic Systems & Drainage

Types of Underground Construction Licenses

Understanding which licenses apply to your specific project scope can save you from costly delays, fines, and potential legal complications. Requirements vary significantly by jurisdiction, so always consult with local authorities and experts before commencing any underground construction project.

FAQs about Underground Construction

What is the difference between trenching and tunneling?

Trenching involves digging a long, narrow excavation that is typically open to the surface and used for laying utilities like water pipes and cables, whereas, tunneling creates an underground passageway that allows for transportation or utility routing while remaining enclosed. Underground tunnels are generally deeper and require additional support systems to prevent collapses

What is the difference between a shaft and a tunnel?

A shaft is a vertical or near-vertical excavation that provides access to underground areas, such as mines, tunnels, or storage facilities, whereas, a tunnel is a horizontal or inclined passage used for transportation, utilities, or drainage. While tunnels connect two points over a distance, shafts are mainly used for access, ventilation, or material transportation.

What is underground utility construction?

Underground utility construction refers to the installation and maintenance of essential infrastructure, such as water supply lines, sewage systems, electrical cables, and telecommunication networks. This type of work involves excavation, trenching, and tunneling to place utility systems underground, protecting them from weather and external damage. 

What does an underground contractor do?

An underground contractor specializes in excavating, installing, and maintaining subsurface structures, such as tunnels, pipelines, drainage systems, and foundations. They are responsible for ensuring the stability of excavations, complying with safety regulations, and using specialized equipment to complete underground projects. 

How do I get experience in the underground construction field?

To gain experience in underground construction, individuals can start by obtaining relevant certifications, such as OSHA safety training, and pursuing technical courses in excavation or tunneling. Entry-level jobs, such as working as a laborer or apprentice with construction firms, provide hands-on experience in the field. 

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