Before you dig

By Cotney Consulting Group. 

Utility locating, trenching and excavation safety. 

Outdoor contractors break ground every day. Landscapers install drainage and irrigation. Lighting contractors bury cable. Pool and spa crews run plumbing and electrical lines. Hardscape contractors excavate for walls, patios and outdoor structures. Sports-surface crews prepare bases and install underground systems. 

The work may appear routine, especially when the excavation is shallow, or the project is on familiar property. But digging changes the jobsite immediately. The moment soil is disturbed, contractors introduce the possibility of utility strikes, cave-ins, unstable ground, falls, flooding and contact with buried hazards no one expected to find. 

An excavation does not have to be deep to be dangerous, and a utility does not have to be large to create a serious emergency. Safe excavation begins before the equipment starts and continues until the ground is restored. 

Start with the utility locate 

No contractor should assume they know what is underground based on visible meters, old drawings or the property owner’s memory. Before digging, contractors should contact 811 and allow the required time for participating utility owners to respond. Every excavation should be treated as a new locate, even when a contractor has worked at the property before. Crews should understand the markings, protect them during the work and verify that all expected utility owners have responded before digging begins.  

Contractors must also recognize that privately owned lines may not be included in the public locate. Irrigation systems, landscape lighting, pool equipment feeds, propane lines, private water service and other owner-installed utilities may require separate locating. 

The safest approach is simple: Never assume the ground is clear because the markings appear limited. 

Marks do not replace careful excavation 

A painted line does not guarantee that a buried facility sits directly beneath the center of the mark or at a specific depth. Utility locations can vary, and soil movement, prior construction or inaccurate records may affect where a line is found. 

As crews approach a marked utility, excavation should become more controlled. Contractors should follow applicable tolerance-zone requirements and use appropriate methods to carefully expose the utility. Depending on the work, this may include hand digging, vacuum excavation or other techniques that reduce the chance of damage. 

Operators should not continue digging aggressively simply because the utility was not found where expected. When something does not make sense, stop and verify. A delay while confirming the location is far less costly than striking electrical, gas, communications, water or sewer service. 

A trench can collapse without warning 

One of the most dangerous beliefs on an excavation site is that the soil looks stable. Trench walls can fail suddenly. Soil type, moisture, vibration, nearby traffic, spoil piles, previous excavation and changing weather can all weaken the excavation. A trench that remained open safely yesterday may not be safe today. 

Trenches five feet deep or greater generally require an adequate protective system unless the excavation is made entirely in stable rock. A trench less than five feet deep may still require protection when a competent person identifies signs of a potential cave-in. Protective methods may include sloping, benching, shoring or trench-box shielding.  

Protective systems for excavations more than 20 feet deep must be designed or approved by a registered professional engineer. Workers should never enter an excavation based on appearance or guesswork. The conditions must be evaluated by someone qualified to identify the hazards and authorized to correct them. 

The competent person has a real responsibility 

A competent person is not simply the most experienced worker on the crew or the person operating the excavator. That individual must be capable of recognizing existing and predictable hazards and must have the authority to take prompt corrective action. The excavation should be inspected before work begins, as needed throughout the shift and after events that could increase the risk of collapse, including rain, vibration, equipment movement or soil sloughing. 

If the competent person identifies unsafe conditions, workers must remain out of the excavation until those conditions have been corrected. This role should be assigned intentionally. It should never exist only on paper. 

Keep spoil and equipment away from the edge 

Excavated soil may appear harmless, but its weight adds pressure to the excavation wall. Equipment, materials and vehicle traffic near the edge create additional loads and vibration. 

Spoil piles, materials and equipment must be kept at least two feet from the excavation edge unless another effective protective measure is used. Contractors should also consider where excavators, compactors, pallets and work vehicles will operate during excavation planning.  

Workers should never stand beneath suspended loads or remain in areas where falling materials could strike them. Spotters and equipment operators must communicate clearly, especially when visibility is limited. The trench edge is not a staging area. 

Safe access must be planned 

Workers should never jump into an excavation or climb out using the walls, pipes, braces or equipment. For trench excavations four feet or more in depth, OSHA requires a safe means of exit, such as a ladder, stairway or ramp. It must be positioned so workers do not have to travel more than 25 feet laterally to reach it.  

The ladder or access point should be stable, unobstructed and located within the protected area. Workers must be able to leave quickly if conditions change. Safe access is not a convenience. During a collapse, water intrusion or atmospheric emergency, it may become a worker’s only way out. 

Water changes everything 

Standing water, runoff and leaking utilities can weaken excavation walls and create additional hazards. Rainfall elsewhere on the property may also unexpectedly flow into the excavation. Crews should watch for water accumulation, seepage and changing soil conditions throughout the day. Pumps or drainage controls may be necessary, but workers should not enter an excavation where water has created unsafe conditions. Electrical equipment around wet excavations adds another layer of risk. Cords, pumps and temporary power supplies must be suitable for the conditions and protected from damage. 

After heavy rain, flooding or any other event that could affect soil stability, the excavation should be inspected again before anyone returns. 

Do not overlook atmospheric hazards 

Some excavations may contain or develop hazardous atmospheres. Oxygen deficiency, toxic gases, flammable vapors or other dangerous conditions may be present near sewers, landfills, contaminated soil, fuel storage areas or certain underground utilities. 

Excavations four feet or deeper may require atmospheric testing when hazardous conditions could reasonably be expected. Workers should not enter until the atmosphere has been evaluated and appropriate controls are in place. Ventilation, respiratory protection or emergency rescue planning may be required depending on the conditions. Atmospheric hazards cannot be judged by sight or smell alone. 

Protect the public and other trades 

Outdoor projects frequently take place at occupied homes, commercial properties, parks, schools and athletic facilities. Open excavations must be protected from customers, children, pedestrians and workers from other trades. 

Barricades, fencing, covers, warning signs and adequate lighting may be necessary depending on the site. Access routes should be maintained, and everyone working nearby should be informed of the locations of excavations. When an excavation crosses a walkway or work route, the contractor should provide a controlled alternative rather than expecting people to step around it. 

An excavation is not safe simply because the crew that created it knows it is there. 

Know what to do after a utility strike 

If a utility is contacted or damaged, work should stop immediately. Workers should move away from the area, warn others and contact emergency services or the affected utility as appropriate. Crews should not attempt makeshift repairs or touch damaged cables, pipes or equipment. 

Following electrical contact, equipment operators may be safest remaining in the cab unless there is an immediate danger such as fire. Following a suspected gas line strike, workers should move away, avoid ignition sources and prevent others from entering the area. 

Every contractor who digs should have an emergency response plan before the first excavation begins. Waiting until a line is struck is too late to decide who makes the call or where workers should go. 

Safe digging is planned digging 

Trenching and excavation safety begins long before the bucket touches the soil. It begins with utility locating, site review, competent-person oversight and a clear plan for protection, access and emergency response. 

Outdoor contractors cannot see every hazard beneath the surface, but they can control how they prepare for it. When crews locate before digging, expose utilities carefully, protect workers from cave-ins and monitor changing conditions, they reduce risk without sacrificing production. 

The ground may look ordinary, but what lies beneath it can change the entire job. Digging safely means treating every excavation with the planning and respect it deserves.