Benching System Excavation

For excavation projects regardless of the type safety and stability of the soils should always be considered. The benching system excavation method is a valuable excavation technique that helps reduce risk for workers by providing easier access to deeper trenching and safer excavations while allowing for compliance and control of work site activities. Unfortunately, many are not overly familiar with how the benching system works or when it’s beneficial. Therefore, we would like to use this guide to explain the benching method, to outline its major regulatory requirements, and to highlight some of the common concerns regarding safety.

What is Benching in Excavation?

A benching system excavation is a method of constructing horizontal step-like formations (benches) into the walls of an excavation or trenching site to create a safer working environment for the workers and equipment used on that project. Rather than excavating the excavation straight down, the side walls of the excavation are shaped using a series of steps, which allow for reduced soil pressure on the walls of the excavation trench, which decreases the potential for a cave-in.

The primary purpose of benching is to stabilize the side walls of an excavation and provide a safe surface for workers and equipment to access the excavation. This system is the most effective when used in cohesive soils because of the ability for the soil to keep its shape as a result of the bench construction. Benching systems can generally be broken down into two categories: simple benching system excavation and multiple benching.

• Simple benching is meant to create horizontal benches that are all of the same height and width. Simple benching systems are most commonly found in excavations that are shallow.
• Multiple benching systems feature benching systems that are built with several horizontal levels stacked on top of one another. Multiple benching systems are advantageous for deeper excavations, where the additional number of benches creates a greater soil support.

With the use of the proper benching system, it is imperative that any project must comply with the benching excavation maximum height, which is dictated by the type of soil in which the project is occurring and the applicable OSHA regulations. Project managers need to be mindful of the maximum height limits of bench excavations because exceeding those limits creates a risk of structural failure and will require the professional planning of the project.

Common Safety Tips for Benching in Excavation

When benching system excavation is used to re-shape the existing surface, all planning and implementation activities must take into account the safe use of benching. The following are some very important safety measures to be taken when implementing benching in excavation:

1. Understand Soil Classifications:

Prior to benching, testing/classification of soil must be done; as defined by OSHA, soil types are indicated as follows:

• Type A: Most stable.
• Type B: Medium stable.
• Type C: least stable (prohibiting use in benching).

Some soils will inherently be unsatisfactory in providing the necessary support for a benching system excavation, such as; Saturated, Granular. Therefore, alternative methods for excavation shall be employed, i.e., slope and/or shore (support).

2. Follow Proper Bench Dimensions:

All domestic benches require a minimum of 2 OSHA-approved width-to-height ratios and the width/height ratios may vary; therefore, accuracy in both dimensions is extremely critical for maintaining the structural integrity of the bench system.

3. Keep Spoil Piles Away from the Edge:

All spoil piles should be located at least a minimum safe distance away from the edge of the excavation. All loose tools and loose & heavy machinery/equipment should also be at a safe distance (greater than minimum distance) from the edge of an excavation due to the added weight that they impose on the edge of the excavation can create potential collapse situations.

4. Inspect the Site Daily:

All excavation sites in a benching system excavation should be routinely inspected at a minimum of once a day, and

• When workers are posted to work on the excavation.
• When there are changes in the weather. 
• Whenever there are additions or removals of equipment/workers on the excavation site
• Whenever changes in the physical soil have been changed/altered.

5. Reinforce Access and Egress:

All ladders/ramps must be located at least 25.0 feet (minimum) apart so that workers have quick access/egress from the trench if necessary and to ensure there are quick escape routes available in case of accidents/emergencies at the trench.

6. Train Workers Thoroughly

Only trained personnel should operate excavation equipment and/or perform tasks in benched trenches.

All excavations that are following the aforementioned safety guidelines will provide an extremely high success rate of maintaining soil stability and protecting employees.

Comparing Benching and Sloping Methods: Which Excavation Technique Is Right for Your Project?

Both Sloping and Benching are common methods of protecting against soil failure, however, while they provide the same level of protection, they have unique characteristics that make them suitable for particular types of applications, costs and types of soils.

Benching System Excavation

• Best for cohesive soils.
• Ideal for deeper trenches requiring stable access.
• Allows workers to move more easily within the excavation.
• Requires more planning but provides structured stability.
• May help reduce overall excavation footprint compared to sloping.

Sloping

Sloping involves cutting the trench walls at an angle away from the excavation. It’s simpler to implement but requires much more horizontal space.

Pros:

• Easier and faster to execute.
• Works well in many soil types, including granular soils.
• No need for step-by-step bench measurements.

Cons:

• Requires a larger work area.
• Can increase project costs due to added excavation volume.

When to Select Sloping or Benching

The choice of which system to utilize depends on the:

• Type of soil,
• Area available for the project,
• Depth of Excavation,
• State and Local Regulations,
• Available budget.

When there is limited space on a construction site, or the excavation is deeper than 4′, the use of a benching system excavation is often the better option. When there is ample open space, and the excavation on the jobsite is less than 4′, the Sloping System may be a better fit for the project.

Many construction companies employ a combination of both methods due to the varying safety and soil conditions for each section of the construction project.

Regulatory Guidelines for Benching Excavation

The United States Department of Labor’s (DOL) Occupational Safety and Health Administration (OSHA) governs the federal standards for excavation safety. The OSHA regulations outline the conditions necessary for using benches, the types of soil that can be used, and how to calculate the maximum bench height for your excavation activity.

Among the key items included in the OSHA regulations for benching system excavation safety are:

1. Soil Type Limitations:

Benching Excavations in Type C Soil are prohibited. Type A and Type B soils can be used for benching with specific ratios and measurements.

2. Bench Height & Width Requirements:

OSHA to maintain worker safety will restrict the maximum height of a bench, and the minimum width, depending on the type of soil used, and the overall slope ratio of the excavation.

Penalties can be imposed for not abiding by these standards, resulting in unsafe working conditions or even legal liability.

3. Site Inspections:

All trench construction on a job must be inspected by a competent person, or an individual qualified by training and experience, to ensure that:

• The trench is safe to work in;
• No adjacent area is in danger of collapse or injury;
• There is a hazard associated with the soil;
• There are no hazards present in the atmosphere.

And changes in the soil may cause an unsafe working environment.

4. Protective Systems for Workers:

Benching system excavation must be part of a complete protective system that is in compliance with the OSHA Subpart P standard.

Hiring professional trenching and benching services, you take the worry and uncertainty out of your project. These contractors have in-depth knowledge of OSHA excavation safety requirements and will ensure that your project adheres to these regulations.

Professional Benching Services in Houston

Precision, safety and compliance when it comes to the construction and utility landscape of Houston especially when it involves trenching for pipelines, drainage systems or foundation work. United Rentals’s professional benching services provided in Houston meet regional specific needs:

Expert Soil Classifications

We classify and evaluate soil to determine if the benching work can be accomplished safely under OSHA standards for soil safety.

Bench Design Customization

Bench Design customers receive an engineered benching design based on soil type, the depth of the trenches, and other environmental considerations related to the benching system excavation project requirements.

Compliance-Focused Cutback Executions

We will execute all cutbacks in compliance with the maximum trench height rule with regard to OSHA’s protective system and use of the Protective System Design for benching and bench constructed areas.

Trained Excavation Personnel

We employ a fully trained work crew to perform all work, using the latest equipment and safety protocols to construct strong, reliable benches.

Total Project Support

Our customers receive full service throughout the project, planning to before the benching, during, and following, with minimal disruption to the project process.

If your project’s success is dependent upon dependable, safe trench excavation work, then United Rentals are the trenching service you need for your project’s success and efficiency.

Conclusion

Among all methods of stabilizing trench walls using cohesive soils, the benching system excavation method offers superior safety and effectiveness than that offered by other techniques. Benching offers improved access to workers during the excavation process, along with better overall stability and support for structural integrity, both of which provide benefit to designs utilized for all types of excavation projects.

Being aware of the differences between benching and sloping systems for stabilizing trench walls, as well as understanding the requirements set forth by OSHA regulations, and knowing when to consult with professionals will impact the ultimate success of an excavation job.

With United Rentals professional benching services, clients will receive reliable, compliant, and project-ready excavation support in Houston.

Frequently Asked Questions About Benching System Excavation