Skip Navigation

Course 802 - Trench and Excavation Safety

1    2    3    4    5    6    Course Homepage     Final Exam      Contact Instructor     Website Homepage
Safety guides and audits to make your job as a safety professional easier

Jobsite Safety and Worker Training

One of the most important responsibilities of field and office management is planning for safety. Most on-the-job problems and accidents directly result from improper planning. Correcting mistakes in shoring and/or shoring after work has started slows down the operation, adds to the cost and increases the possibility of an excavation failure.

Contractors should develop safety checklists to make certain there is enough information about the jobsite and all needed items, such as safety equipment, are on hand.

To help ensure safety in trenching and excavations, you will need to take these specific conditions into account:

  • Soil types and layers
  • Traffic
  • Nearness of structures and their condition
  • Surface and ground water conditions
  • The water table evaluation
  • Overhead and underground utilities
  • Weather

These and other conditions can be determined by jobsite studies, observations and consultations with local officials and utility companies. Underground installations, such as sewer, telephone, water, fuel and electrical lines, need to be found before starting a job. If underground installations are found, OSHA regulations require they must be properly supported.

The contractor MUST contact the utility companies involved and inform them of the work before starting the trench or excavation. This should be done at least two business days before you begin your work.

The utility will help you with certain tasks, such as the following, to make sure you are safe:

  • Coordinate work schedules
  • Identify temporary mechanical barriers that prevent contact with the lines
  • De-energize and ground the lines
  • Temporarily raise or move the lines

You’re responsible for all damages and costs that result from an electrical accident. Also, there could be a penalty from OSHA of up to $70,000 for each offense in addition to the cost of injuries and repairs!

Employee Training

Cooperation between supervisors and employees is necessary to make sure safety policies are implemented effectively. Each supervisor must understand his or her degree of responsibility for providing a safe working environment.

The cooperation of all employees requires their recognition of safety hazards and the needed safety precautions.

Employees need to be trained in the following areas:

  1. Trenching and excavating hazards
  2. Soil identification
  3. Safe slopes for different soil types and conditions
  4. Stress patterns on trench walls from soil and spoil, equipment, and vibration caused by equipment and traffic
  5. Effects of nearby buried utilities, building foundations and lengthy exposure to the elements on trench side walls and other excavations
  6. Effects on trench and excavation conditions from severe weather (such as excess water, freezing temperatures, unexpected heat or long-term drying)
  7. Recognition of buried drums, containers, tanks and wells

Employees also need to be trained to follow the proper procedures to involve the electrical power company, health department and other agencies when they find unforeseen objects, such as wells, sewage disposal systems, cemeteries, and historical or architectural artifacts.

On-the-Job Follow-up

Once the job begins, each employer should stay informed of the safety aspects of the project as well as the progress of the work. This is called “on-the-job follow-up” and involves a series of inspections to find potential hazards and correct them before cave-ins or other accidents happen at the site. When management requires daily reports and then acts on them, it then makes everyone feel more confident that everyone is meeting job safety responsibilities.

Surface Crossing of Trenches

Surface crossing of trenches should be discouraged; however, if trenches must be crossed, they are only permitted under the following conditions:

  • Vehicle crossings must be designed and installed under the supervision of a registered professional engineer.
  • Walkways or bridges must be provided for foot traffic. These structures must:
    • Have a minimum clear width of 20 inches
    • Be fitted with standard rails
    • Extend a minimum of 24 inches past the surface edge of the trench
Employees must be protected from loads or objects falling from lifting or digging equipment.
Employees must be protected from loads or objects falling from lifting or digging equipment.

Exposure to Falling Loads

Employees must be protected from loads or objects falling from lifting or digging equipment.

Here are some procedures to protect your employees:

  • Employees are not permitted to work under raised loads
  • Employees are required to stand away from the equipment that is being loaded or unloaded
  • Equipment operators or truck drives may stay in their equipment during loading and unloading, if the equipment has a cab shield or adequate canopy
Water accumulation in a trench must be taken seriously.
Water accumulation in a trench must be taken seriously.

Standing Water and Water Accumulation

Methods for controlling standing water and water accumulation must be provided.

The methods should consist of the following, if employees are permitted to work in the excavation:

  • Use of special support or shield systems approved by a registered professional engineer
  • Water removal equipment, i.e., well pointing, used and monitored by a competent person
  • Safety harnesses and lifelines used
  • Surface water diverted away from the trench
  • Employees removed from the trench during rainstorms
  • Trenches carefully inspected by a competent person after each rain and before employees are permitted to re-enter the trench

There are some hazards stemming from water in an excavation. For example, the contractor may undermine the sides and make it more difficult to get out of the excavation.

The OSHA Standard prohibits employees from working without adequate protection in excavations where water has accumulated or is accumulating. If you use water removal equipment to control or prevent water accumulation, you must make sure a competent person monitors the equipment and its operation to ensure proper use.

OSHA standards also require the use of diversion ditches, dikes and other suitable means to prevent water from entering an excavation and to provide drainage of the adjacent area. A competent person must also inspect those excavations that are subject to runoffs from heavy rains.

Real-Life Scenario

This worker is buried up to his neck.  The forces pushing on his body can be enormous.
This worker is buried up to his neck. The forces pushing on his body can be enormous.

Two employees were installing storm drain pipes in a trench, approximately 20-30 feet long, 12-13 feet deep and 5-6 feet wide. The side walls consisted of unstable soil undermined by sand and water. There was 3-5 feet of water in the north end of the trench and 5-6 inches of water in the south end. At the time of the accident, a backhoe was being used to clear the trench. The west wall of the trench collapsed, and one employee was crushed and killed.

Inspection Results

As result of the investigation, OSHA issued citations for one willful, one serious, and one-other-than-serious violation of its construction standards.

OSHA's construction safety standards include several requirements which, if they had been followed here, might have prevented this fatality.

Accident Prevention Recommendations

  1. Employers must shore, slope sheet or brace sides of trenches in unstable material (29 CFR 1926.652(b) or 1926.651(c)).
  2. There must be a means of escape from a trench such as ladder (29 CFR 1926.652(h)).
  3. Trench work is to be inspected daily by a "competent person". When there's evidence of cave-ins or slides, all work must stop (29 CFR 1926.650(i)).
  4. Water must not be allowed to accumulate in a trench (29 CFR 1926.651(p)).
  5. Excavation material must be moved at least two feet from the edge of the trench (29 CFR 1926.651(i)).
  6. Where heavy equipment is operating near a trench, extra precautions must be taken due to the extra load imposed on the ground (29 CFR 1926.651(q)).
If there are any hazardous conditions, you must provide the employee controls, such as proper respiratory protection or ventilation.
If there are any hazardous conditions, you must provide the employee controls, such as proper respiratory protection or ventilation.

Hazardous Atmospheres Inside Excavations

Also, OSHA has specific training requirements for all employees who are required to enter confined or enclosed spaces.

A competent person must test an excavation deeper than 4 feet or where an oxygen deficiency or hazardous atmosphere is present or could reasonably be expected before an employee enters the excavation. This could include a landfill or where hazardous substances are stored nearby.

If there are any hazardous conditions, you must provide the employee controls, such as proper respiratory protection or ventilation. Also, you are responsible for regularly testing all controls used to reduce atmospheric contaminates to acceptable levels.

If unhealthful atmospheric conditions exist or develop in an excavation, you must provide emergency rescue equipment such as breathing apparatus, safety harness and line, and basket stretcher. Make sure this equipment is readily available, in case of an emergency.

Conducting an On-site Inspection

The OSHA standard requires a competent person to inspect an excavation daily. They need to watch for possible cave-ins, failures of protective systems and equipment, hazardous atmospheres, or other hazardous conditions. Inspections also are required after natural events such as heavy rains or manmade events such as blasting that may increase the potential for hazards. If the inspector finds any unsafe conditions during an inspection, you must clear employees from the hazardous area until you take safety precautions.

If the competent person finds any hazardous conditions, all exposed employees must leave the hazardous area until necessary safety precautions are taken.

Larger and more complex operations should have a full-time safety official who makes recommendations to improve implementation of the safety plan. In a smaller operation, the safety official may be part-time and usually will be a supervisor.

Supervisors are the contractor's representatives on the job. Supervisors should conduct inspections, investigate accidents, and anticipate hazards. They should ensure that employees receive on-the-job safety and health training. They also should review and strengthen overall safety and health precautions to guard against potential hazards, get the necessary worker cooperation in safety matters, and make frequent reports to the contractor.

You’ve made it! Now, it’s time to tackle your last module quiz!

VIDEO

Instructions

Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Most on-the-job problems and accidents directly result from ________.

2. The contractor does NOT have to contact the utility companies to inform them of the work before starting the trench or excavation.

3. In regard to excavation and trenching, employees need to be trained in ________.

4. The OSHA standard requires a competent person to inspect an excavation ________.

5. Walkways or bridges must be provided for foot traffic. These structures must ________.


Have a safe day!

Important! You will receive an "error" message unless all questions are answered.