Injuries sustained in trenching operations can be due to unsafe conditions, unsafe acts, or a combination of the two. If the only “solution” to an unsafe condition is to simply “man up” and perform the work, performing the work is an unsafe act.
Unsafe conditions
If you understand what conditions are unsafe and what corrective action to take, then you can make performing the work a safe act. In trenching, the Buried Objects Survey (BOS) is your first line of defense.
The BOS is typically conducted with ground penetrating radar (GPR); it’s not the same as the line survey conducted to detect utility lines. You need both. Five unsafe conditions are BOS-related:
1. There’s no BOS in the work documents. Contact the person responsible for the BOS and determine if one was completed. If so, obtain a copy. If not, pack up because you can’t work this site until a BOS has been performed.
2. The BOS doesn’t cover the entire trenching route. You can’t trench any portion of the route the BOS doesn’t cover.
3. Someone else recently dug a trench, but the BOS doesn’t show the new trench. Find out if your BOS is current, because this indicates it’s not.
4. The BOS has expired. Order a new BOS.
5. While you’re digging, the trencher is pulling up debris. This can cause it to jam or even break. Check the date on your BOS. You may need a new BOS and/or a new route.
Other unsafe conditions include:
• The trenching route crosses a walkway or other traffic area. Establish and mark out a detour path, then rope off the trenching route.
• Dogs, kids, and/or adults are in the work area. Contact the site owner/manager. Proceed only after the area is clear. If the site owner is the problem, for example, insisting on overseeing the work, stop. Explain that you need the work area clear for everyone’s safety. This also applies while unloading, fueling, cleaning, or loading equipment. You can’t have distractions.
• You’ve got the emergency numbers of the electric, gas, and water utilities on your smartphone, but there’s no cell signal at this location. Find a landline nearby or find a hilltop or other spot from which you can make a call; do this before an emergency arises — same for emergency medical. If no such alternative is available, your project manager must address the issue.
Safety measures
Certain safety measures apply when using any rotating equipment:
• Protect your ears. Know the approximate noise level you will encounter, and wear the appropriate hearing protection. You may need ear muffs, not just foam roll-up inserts.
• Protect your eyes. In most cases, safety glasses provide the necessary eye protection. It helps if you have a spare pair of them. It also helps if you have lens cleaning cloths.
• Protect your feet. Sneakers are not adequate. Several companies make industrial-quality work boots. These boots often have toe protection (e.g.,“steel toe,” though another material may be used), plus features to reduce fatigue. Check your work boot soles periodically; if the tread’s wearing off, you have a slipping hazard.
• Protect your hands. Wear work gloves appropriate to the conditions. Keep hands away from rotating parts unless the machine is off and rendered unable to start. For example, unplug the ignition coil wire if the machine runs on gasoline.
• Inspect the area. Before starting the work (in this case, trenching) look for all possible dangers, and take action to protect yourself from them. If you were cutting up old boards with a rotary saw, you would look for and remove any nails, staples, or screws in the wood first. With trenching, you should look for and remove any brush, fallen limbs, or trash that is on the intended trenching path.
• Pay attention. Don’t be daydreaming and don’t divert your gaze from the work. Stay focused at all times. When loading or unloading the trencher, make sure anyone helping you is also paying attention.
Unsafe acts
The original focus of OSHA, and thus industrial safety programs, was to address unsafe conditions. While unsafe conditions should be addressed, unsafe acts are the primary source of deaths and injuries.
Unsafe acts can be passive or active; you must guard against both types. You passively increase your risk of injury by neglecting to do the basic safety functions. You actively increase your risk of injury by doing things that are unsafe.
These are examples of unsafe acts:
• Manhandling a trencher onto or off the trailer. Trencher manufacturers provide dollies or other means for rolling small trenchers on and off trailers. Large trenchers are typically self-powered and can be driven off (rather than rolled off by hand). Check ramp position before moving that trencher.
• Trenching without proper marking from a buried line survey. Gas, power, and communication lines may be in shallow soil. Utilities have programs for identifying what’s under the surface.
• Trenching outside existing survey markings. Typically, buried lines are marked with spray paint and flags (or other markers). The boundaries of the surveyed area should also be marked. If you don’t know the boundaries, ask.
• Adding fuel when a trencher is hot. It may be hot from use or from being in the sun. Pouring gasoline onto a hot surface is just asking for a fire. Fuel the trencher at the start of the shift before using it. If you break for lunch, leave the trencher in the shade, and fuel it again before using it.
• Walking a trencher up a hill. If you must trench on a hill, trench in the downhill direction (assuming you are behind the trencher).
• Reaching into the business end of a trencher to remove a tree root or other object. Instead, set the trencher controls to “off.” This may be as simple as turning the ignition key. Then, use a tool to pry loose the stuck object, or pull it out. Never use your fingers to grab something stuck in the trencher screw/blades. Note also that while losing your fingers is traumatic enough, your whole arm could get pulled in. As an added precaution, roll up long sleeves if you’re wearing them.
Unexpected problems
You have your BOS and your line survey, and both are current. But suppose you hit a buried cable. What do you do? You stop, turn the trencher off, and look very carefully at that cable and the ground around it. Step away from the cable, but not into any standing water or onto any metallic objects (e.g, a ground rod). If it’s a power cable instead of a signal cable, rope off the area. Call the electric utility, and wait for resolution before resuming work.
What if you hit a gas pipe? Again, stop and turn the trencher off. Don’t assume you didn’t damage the pipe. You know which place to call immediately. After you get off the phone with the gas company, secure the area with a wide perimeter. If police or firefighters arrive before the gas company does, brief them on the situation, and then do what they ask.
Final tips
Other safety practices also come into play. These include using the right trencher for the job, inspecting trailer tie-downs, and inspecting trailer lights. Your company also should follow the recommended procedures for storing, maintaining, cleaning, and fueling any trencher it owns.
If your company has employees use trenching equipment, OSHA regulations require your company to address trenching in its safety policy. The trenching regulations are found in 29FCR1926, Subpart P - Excavation. This runs several pages, and it contains many tables and illustrations. If you’re involved in trenching, you would benefit from reading Subpart P in addition to undergoing your company’s safety training and trenching training.
Most importantly, pay attention to what you are doing and where you are doing it. Identifying a danger and protecting yourself against it is always preferable to dealing with the consequences of a danger that becomes a tragic event.
Lamendola is an electrical consultant located in Merriam, Kan. He can be reached at [email protected].
