An engineered protective system supports the underside of a stone bridge.

When Do You Need an Engineer for Your Trench Shoring Design?

Protecting workers in trenches is a critical aspect of any construction project. OSHA, the Occupational Safety and Health Administration, mandates that trenches deeper than five feet have protective systems such as sloping, benching, shoring, or shielding in place. The choice of protective system is influenced by factors such as soil type, weather conditions, and trench depth. OSHA requires a competent person to be present at the site to assess soil conditions, choose appropriate protective systems, and ensure compliance with safety regulations. The competent person should have extensive knowledge and experience to identify and address potential hazards.



The deeper the trench, the more important it is to have protective systems in place — and having a competent person may not be enough. In deeper excavations, shoring systems like hydraulic or timber shoring may be necessary. OSHA does not explicitly require the presence of a registered professional engineer (PE) for all deep excavations. Yet there are instances where their involvement is strongly recommended or necessary.






Instances Where Having a Professional Engineer for Trench Shoring Design Is Ideal


OSHA regulations emphasize the importance of a competent person who is capable of identifying and addressing hazards in trenching and excavation work. In some cases, a PE may serve as the competent person, taking responsibility for designing protective systems and ensuring the overall safety of the excavation.


Additional Requirements for Deep Trenches


For trenches deeper than 20 feet (6.1 meters), OSHA requires that a registered PE design a protective system unless the excavation is made entirely in stable rock.


Site-Specific Considerations


OSHA regulations recognize the variability of soil conditions and excavation sites. In situations where the soil is not uniform, or other site-specific conditions pose potential hazards, a PE may be necessary to assess the situation and design appropriate protective measures.


Sloping, Benching, and Shoring Design


While a competent person can determine the appropriate slope, benching, or shoring for trenches up to 20 feet deep, a PE may be required to design protective systems in deeper excavations or more complex soil conditions.


Engineering Analysis


OSHA's regulations allow for using tabulated data or engineering analysis to design protective systems. A PE may perform the necessary analysis to ensure that the chosen protective system is adequate for the specific conditions of the excavation.






Professional Engineers and Deep Excavations


Construction companies often rely on their own plans for trench shoring design. However, the involvement of a registered professional engineer is necessary when the excavation exceeds 20 feet deep or when there are heavy surcharges nearby. Heavy equipment, stockpiles, roads, bridges, and buildings can all cause surcharges, making a PE’s guidance and approval indispensable.


OSHA's excavation standard, found in Part 1926, Subpart P, addresses safety requirements for trenching and excavation activities. The standard has specific guidelines related to shoring systems designed for excavations of 20 feet or less. Contractors have four options for setting up a shoring system under the standard.


Option 1: Timber Shoring or Aluminum Hydraulic Shoring


Contractors can use pre-designed shoring solutions, such as timber shoring or aluminum hydraulic shoring, for excavations up to 20 feet deep. These systems are designed to be easily deployable and are based on standardized configurations, not for when there are additional surcharges to consider. 


Option 2: Shoring Designed to the Manufacturers' Data


In this option, contractors can design a system by following the manufacturers' tabulated data for shoring equipment. This engineering documentation shows that the manufacturer's engineer has evaluated the equipment and deemed it suitable for a particular depth, soil type, and site conditions.


Option 3: Shoring Designed Using Data from an Independent Professional Engineer


 Like option 2, this option allows contractors to use tabulated data from independent professional engineers who have developed this data independently of the manufacturer.


Option 4: Custom-Engineered Design from a Registered Professional Engineer


This option involves a site-specific, custom-engineered solution for the shoring system developed by a registered Professional Engineer in the state where the work is taking place. This option is chosen when the excavation site has specific conditions or additional surcharges that require a more detailed and site-specific engineering analysis.


Although they are not required for every project, PEs bring a wealth of knowledge to the table, ensuring that trench shoring designs adhere to OSHA regulations and industry best practices. They perform detailed analyses to assess soil conditions, potential hazards, and structural loads, tailoring solutions to the specific needs of each project.






Types of Professional Engineers Involved in Deep Excavations


Various types of engineers contribute to the success of trench shoring projects. Three key types of PEs associated with deep excavation projects include:


Geotechnical Engineers


Geotechnical engineers are crucial in assessing and understanding the soil and rock conditions at the excavation site. For trench shoring, they analyze the stability of the soil to determine the appropriate shoring systems needed to prevent collapses. They consider factors such as soil type, water table levels, and potential for ground movement. They can also provide recommendations for the design of retaining structures and foundation systems based on their understanding of the subsurface conditions.


Civil Engineers


Civil engineers play a broader role in the planning and design of the entire excavation project, including trench shoring. They are responsible for the layout and integration of the excavation within the overall site development. In trench shoring, they may design the overall site plan, drainage systems, and coordinate the placement of utilities. They work closely with geotechnical engineers to incorporate soil information into the design and ensure that the excavation aligns with local building codes and regulations.


Trench Safety Engineers


Trench safety engineers specialize in ensuring the safety of workers during excavation, particularly in trenches. Their primary focus is on implementing measures to prevent trench collapses and protect workers from potential hazards. They work on designing and overseeing the installation of shoring systems, which may include trench boxes, sloping, or benching techniques. They also develop safety protocols, conduct inspections, and ensure compliance with safety regulations and standards.


The collaboration among these engineering disciplines can be essential for the successful and safe execution of shoring a trench in deep excavation projects. These types of PEs may also need to consider lateral loads, exposure to hazards, and the potential impact of heavy equipment during trench shoring design. These factors are crucial to the overall stability and safety of the trench, aligning with OSHA's emphasis on hazard prevention and control.


Engineer Trench Shoring Success with Sunbelt Rentals


When it comes to deep excavations, safety should be your top priority. Partnering with a Professional Engineer (PE) is not just a good idea but a must. Their expertise ensures that your trench shoring design meets the strict standards set by OSHA, creating a safe and secure work environment for everyone involved. And when it's time to put that design into action, Sunbelt Rentals Trench Safety team members are available to assist you every step of the way.



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