Excavation is essential for installing utility lines, but it carries significant risks. Workers must be aware of potential hazards and take precautions to avoid them. OSHA 1926.651 provides regulations to ensure safety throughout the process.

OSHA 1926.651 Excavation Compliance Requirements

OSHA 1926 as a whole covers safety and health regulations for construction, and OSHA 1926.651 specifically addresses excavation requirements for underground utility installation projects. Here’s an overview of how to ensure compliance. 

Locate All Underground Utilities

Sewer lines, telephone lines, electric cables and other utility installations that installation teams are expected to encounter should be identified before excavation. This information helps map out the best areas and paths that would cause minimal to no disturbance. 

If utility companies cannot respond to requests to reveal underground utility installations within 24 hours, assuming state or local law does not dictate a longer period, or cannot establish the exact location of these installations, teams can go ahead. Keep in mind to check if state or local law allows a longer wait period for utility companies or owners to respond. 

Some companies can provide at least an estimated location of existing underground installations. From there, a team needs to narrow down the exact location using safe methods, such as underground locating tools. 

Protect Workers from Cave-Ins

Cave-ins may occur while an excavation is open, but it’s critical to keep it open to perform the utility installation. Temporary underground structures, such as protective barricades, are set up to protect or support employees. These will be removed after the operation.

Personal protective equipment (PPE) should also be worn at all times to ensure each person is highly visible. There are also protocols in place, such as daily inspections to assess the risk of cave-ins during a workday. 

Water accumulation in an excavated area can pose a threat, so employees are barred from working unless water removal or other precautions have been implemented. If the excavation and utility installation are interrupting surface water drainage, further inspections are required.

Have a Competent Person Inspect the Site

OSHA 1926.651 emphasizes the importance of having a competent person throughout the different phases of excavation work. There are additional resources that further outline the qualifications of a competent person for excavation safety.

Get protective systems or equipment: A competent person should be able to choose and monitor the equipment used to create a safer environment, such as water-removal tools. They should also classify soil and rock deposits to ensure appropriate protection.Inspect trench and protective systems: Inspections should be run to ensure that all trench and protective systems are up to standard. If a competent person finds evidence of possible cave-ins, they should authorize the immediate removal of employees. 

Ensure safe access and egress: A competent person qualified in structural design is responsible for designing the structural ramps. The goal is to have safe access and egress for employees and equipment. 

Protective Systems for Trench Safety Utility Installation

Protective systems can be configured in various ways to suit the conditions of the excavated area. It is possible to combine several protective system types depending on the situation. 

Sloping 

Sloping can be beneficial for deeper excavations, and the overall slope can be adjusted depending on the soil type in the area. Keep in mind that a registered professional engineer should design the area. 

Benching

Benching is a strong method since it excavates the sides of an excavation area to ensure horizontal levels. Proper bench loading should be observed, given that material needs to be removed from the premises. Focus on setting the right bench height and minimizing the excavator's swing distance. The haul truck should also be parallel to the bench, with a bed angle of approximately 50 to 60 degrees for stable yet efficient loading.

Shielding

In shielding, the space between the boxes and the excavation side is typically backfilled to stop lateral movement. While shielding is effective, it should be designed to withstand loads exceeding its own system, even if the likelihood of such exposure is low. 

Shoring

While similar to shielding, shoring focuses more on preventing soil movement in excavated areas rather than on actively protecting workers. Aluminum hydraulic, timber and other materials are used for the support system.

Shoring systems can involve several components such as posts, wales, struts and sheeting. Prefabricated parts can speed up installation. 

Underground Utility Strike Prevention During Excavation

Damage prevention is critical to avoid utility strikes throughout the excavation process. A study noted that 470,000 damage incidents occur across more than 35 million miles of underground utilities annually. One of the main reasons for this could be inadequate damage-prevention training practices.

Very few practice general damage prevention training, and even fewer follow post-damage training protocols. It’s critical to implement these processes to mitigate utility strikes and ensure long-term construction worker safety. 

Handling Hazardous Atmospheres in Deeper Excavations

Aside from utility strikes, workers should also be wary of hazardous atmospheres during deeper excavations. Oxygen deficiency and toxic gases can create a constrictive space. A competent person must test the atmosphere daily to authorize entry.

Safe access and egress should be prioritized. Ladders within 25 feet of workers in trenches should be at least 4 feet deep. Exercise caution when using ladders, as construction workers account for half of ladder-related fatalities each year.

Creating an Excavation Hazard Assessment for Site Preparation Projects

A competent person must conduct a thorough excavation hazard assessment before site preparation to develop a comprehensive approach to trenching and excavation. The first step is to record the task details, like site name, location and personnel involved.

Follow up with a robust risk assessment that has a description of the hazards and their risks. The risks can also be categorized into four categories— primary hazards, physical hazards, chemical hazards and ergonomic hazards. 

Rate how high the risk of those hazards is, as well as the main people at risk. From there, a competent person can recommend risk-reduction measures to be implemented before site preparation operations. 

Prepare for Excavation Safety and Utility Installation

Safety compliance should be a priority, especially with critical excavation operations for utility installation projects. Refer to the OSHA 1926.651 regulations to cover all bases and safeguard employees, equipment and structures involved.