Excavation Safety

OSHA’s Construction Standard, Subpart P covers excavation and trenching safety regulations.

Trenching, shoring and excavation work presents serious hazards to all workers involved. Cave-ins pose the greatest risk and are more likely to result in fatalities than other excavation-related incidents.

Just one cubic yard of soil can weigh as much as a car, making unprotected trenches a potentially fatal hazard. Employers must ensure that workers enter trenches only after adequate protections are in place to address cave-in hazards. Other potential hazards associated with trenching work include falling loads, hazardous atmospheres, and hazards from mobile equipment.

No matter how many trenching, shoring, and backfilling jobs a company has done in the past, it is important to approach each new job with care and preparation. Many on-the-job incidents result from inadequate planning.  Waiting until after the work starts to correct mistakes in shoring or sloping slows down the operation, adds to the cost of the project, and makes a cave-in or other excavation failure more likely.

Before starting work, it is important to know as much as possible about the jobsite and the materials needed to perform the work safely and in compliance with OSHA standards. Companies can gather the information they need through jobsite studies, observations, test borings for soil type or conditions, and consultations with local officials and utility companies. This information will help determine the amount, kind, and cost of safety equipment needed to perform the work safely.

Factors to consider when starting a new project include:

• Traffic
• Proximity and physical condition of nearby structures
• Soil Classification
• Surface and ground water
• Location of the water table
• Overhead and underground Utilities
• Weather
• Quantity of shoring or protective systems that may be required
• Fall protection needs
• Number of ladders that may be needed
• Other equipment

Estimated location of utility installations (sewer, telephone, fuel, electric, and water lines) must be determined prior to opening an excavation. When utility companies or owners cannot respond to requests to locate underground utility installations within 24 hours, you may proceed with caution, provided detection equipment is used to locate utility installations. Remember 811, Call before you dig!

For all trenches deeper than 5 feet deep or for any trench that shows signs of cave-in, OSHA requires the following protective systems to protect workers from cave-ins:

• Sloping
• Benching
• Shoring
• Shielding

A competent person should examine any damaged materials or equipment to evaluate its suitability for continued use. If a competent person cannot assure that damaged material or equipment can support the intended loads or is otherwise suitable for use, the materials and equipment must be removed from service until evaluated and approved by a registered professional engineer.

Water Accumulation

Water in an excavation can undermine the sides of the excavation and make it more difficult for workers to get out of the excavation. OSHA standards prohibit employers from allowing workers to enter an excavation where water has accumulated or is accumulating unless adequate precautions are taken to protect workers. 

Such precautions include:

• Special support or shield systems to prevent cave-ins
• Water removal to control the water level
• The use of a safety harness and lifeline

If excavation work interrupts the natural drainage of surface water, use diversion ditches, dikes, or other suitable means to prevent surface water from entering the excavation and to provide adequate drainage of the adjacent area. 

Atmospheric Testing

In an excavation greater than 4 feet in depth where an oxygen deficiency or a hazardous atmosphere is present (or could reasonably be expected), atmospheric testing is required.  If there are any hazardous conditions present, ensure that adequate precautions are taken to prevent employee exposure to those conditions. Such precautions include providing workers with proper respiratory protection or ventilation. 

If engineering controls are used to reduce the level of atmospheric contaminants to acceptable levels, testing must be conducted as often as necessary to ensure that the atmosphere remains safe. If hazardous atmospheric conditions exist or may reasonably be expected to develop in an excavation, ensure the availability of emergency rescue equipment, such as breathing apparatus, a safety harness and line, or a basket stretcher. 

Additional hazards and protections

To reduce the risk of hazards on excavation sites:

• Know where underground utilities are located before digging
• Keep excavated soil and materials at least 2 feet from trench edges
• Keep heavy equipment away from trench edges
• Identify any equipment or activities that could affect trench stability
• Test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when workers are more than 4 feet deep
• Inspect trenches at the start of each shift
• Inspect trenches following a rainstorm or other water intrusion
• Inspect trenches after any occurrence that could have changed conditions in the trench
• Ensure that personnel wear high visibility or other suitable clothing when exposed to vehicular traffic

These are just some key points to keep in mind when it comes to excavation sites. If you are looking for a full comprehensive training program for excavations check out our DIY In-house Training Kit or take a look at our online training options. 

Call 866-627-3850 or email us at sales@jjsafetyllc.com to learn more.