Trenches are a dangerous part of any excavation job, which is why safety should be at the forefront of your trenching operations. Unstable rocks and soil can collapse at any time with workers inside, resulting in injuries or fatalities. Collapsing walls are preventable with the safe installation of trench boxes and proper training. Installing trench boxes takes great care, and the safety of an excavation project requires properly trained workers and machine operators.
Ohio — The Cat Rental Store has trench box solutions available for your excavation or trenching projects to help get the job done safely. With our expertise and high-quality Cat® equipment, we can assist you in choosing the right trench box for your business and help you understand trench box installation best practices.
What Is a Trench Box?
Also known as a trench shield, a trench box is imperative to have on-site in excavated areas and is most ideal for trenches that are narrow and evenly sloped. A trench shield is a fixture made of aluminum or steel that fits inside a trench. It allows workers to safely and quickly enter and exit a ditch via a ladder attachment for easy access. The box’s main purpose, however, is to protect workers inside the trench from possible cave-ins.
A shield provides a protective barrier between your workers and the trench walls and has adjustable spreaders that allow you to customize the box’s size to the size of the trench. This is helpful if your operations involve several trenches throughout a project. You can choose between an aluminum or steel trench box solution. Deciding which trench box is right for your construction site depends on the scale of your projects and the type of terrain you operate in.
An aluminum shield box is great for small-scale projects and shallow-earth trenches because they are lightweight and easy to maneuver. Steel options are heavy-duty and more durable to withstand rough terrain and large-scale projects. Both solutions are weather-resistant and sturdy, meaning they also won’t corrode, warp or bend.
Although trench boxes appear similar to manholes, they have adjustable plate walls and bars to protect workers from collapsing rocks, soil and other materials. They’re often used in multiples to support the full length of a trench. In comparison, a manhole box has four solid walls that completely enclose workers.
Shield boxes are a cost-effective and reliable solution when total trenchless options aren’t viable compared to total soil removal.
Trench Box Installation Methods
Trench shields are most useful in construction zones that have loose soil or in environments that are wet from rain or other weather conditions. While these structures increase the stability of a trench, they are not 100% collapse-proof. This is why safe and proper installation techniques are imperative to minimize the risks.
Learning how to install a trench shield begins with a piece of heavy equipment, like an excavator. Groundworkers install the trench box with the help of an excavator, then the machine lowers it into place. Proper trench box installation methods are as follows:
- Lower one panel onto a skid with the strut housings facing upward.
- Adjust the struts to the necessary width of the trench.
- Secure the struts in place using pins and R-clips.
- Invert the second panel.
- Use the panel’s handling points to align it over the struts.
- Lower the panel into the struts.
- Insert the remaining pins and clips.
- Make width adjustments again if necessary by removing the pins, lifting the top panel and moving it to the appropriate width.
- Reinstall the pins and clips.
- Lift the trench box onto its cutting edge using the excavator.
- Push the trench shield into the ground, one side at a time, until it reaches the appropriate depth.
- Install handrail panels for extra safety.
- Remove soil from the trench by digging between the panels.
- Move the box along as the trench gets deeper.
- Stack extensions onto the base frame to maintain the correct height above the soil.
Always use heavy machinery to lift, move and push trench boxes into place to avoid groundworker injuries.
Trench Box Extraction Methods
After you and your crew complete a section of the trench or the entire project, refer to this step-by-step process for proper trench box extraction:
- Remove the handrail panels.
- Place and compact backfill soil according to the trench box’s specifications.
- Backfill in stages while removing the shield.
- Use a four-leg chain around the lifting points to remove the box. Alternatively, use a two-point chain back and forth from one end to the next until the shield is free.
- Use a single chain on one corner at a time if the previous methods don’t work.
- Store the entire trench box on level ground or dismantle it for future use.
- Keep the pins and clips in place if dismantled.
Train your heavy equipment operators and ground crew in proper trench box installation and extraction practices to ensure a safe work site. Between 2013 and 2017, 97 trenching fatalities occurred, with an average of 19 deaths per year. Though small amounts of soil and rock may seem harmless, one cubic yard of dirt can weigh about 3,000 pounds. You can avoid trenching disasters by relying on shield boxes.
Safety Tips for Trench Box Installations
According to the Occupational Safety and Health Administration (OSHA), all construction zones must install a trench box if working in an excavated area of more than 5 feet deep. Your shields must also comply with the following:
- Be certified by a professional if the trench is more than 20 feet deep.
- Reach at least 18 inches above the soil surface.
- Rest no more than 2 feet from the trench bottom when added to the slope dimensions.
- Withstand the soil type and depth pressure of your projects.
Before excavating a trench, consider the following:
- Assess the weights, widths and internal dimensions a shield box can handle according to the owner’s manual.
- Clear the area of other workers before lowering or lifting materials.
- Inspect trench shield pieces before each use.
- Locate any underground components like pipes and electrical lines before digging.
- Use certified lift equipment operated by trained personnel.
Here are a few other safety tips to be aware of during the installation process.
- Attach hooks properly.
- Backfill any voids between the outside panels and the trench to prevent ground movement.
- Don’t adjust the struts without the box lying flat.
- Don’t use excessive force to push down the panels farther into the trench.
- Double-check that the pins and clips are securely fitted.
- Ensure no one is in the box when installing or extracting.
- Install handrail panels once the box reaches its required depth for increased safety measures.
- Lay the trench box flat before taking it apart.
- Only lift at the designated lifting and handling points.
- Only push the panels in the corners by using the bucket of an excavator.
- Use a secure ladder to enter and exit the trench, and never leave the designated safety zone.
- Wear personal protective equipment like a hard hat, steel-toed boots, gloves and a reflective vest.
Trench boxes are crucial for any excavation project, no matter the line of work. Proper trench box installation methods and safe practices are what can make all the difference to ensure the shields protect you and your workers throughout each project.
Trust Ohio — The Cat Rental Store to Keep You Safe
For whatever excavation job you have next, Ohio — The Cat Rental Store can help you choose the right size and type of trench box to keep your crew safe. When you partner with us, you receive access to our large inventory of steel and aluminum shield boxes and 24/7 support. At Ohio — The Cat Rental Store, we’re known for our excellent customer service, whether you need multiple solutions or a single box.