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Trenching and Excavation

Because of a continuing incidence of trench/excavation collapses and accompanying loss of life, in October of 1997, TOSHA placed renewed emphasis on its Special Emphasis Program on Trenching and Excavation. Trenching and excavation work creates ex­tremely dangerous hazards to workers. Yet compliance with TOSHA construction stan­dards applicable to such operations is some­times bypassed because of economic pressures, time constraints, a belief that compli­ance is unnecessary, or an expectation that these short-term operations will be completed before an accident can occur.

Under this Special Emphasis Program, all TOSHA compliance and consultative services personnel are instructed to be on the lookout for trenching or excavation work sites. Per­sonal observation, reports of imminent dan­ger, fatality/catastrophe reports, safety and health agency referrals, employee complaints, and media reports are also utilized to locate trenching and excavation work. Each occurrence is handled with the appropriate intervention by TOSHA.

Under this Special Emphasis Program, all TOSHA compliance and consultative services personnel are instructed to be on the lookout for trenching or excavation work sites. Per­sonal observation, reports of imminent dan­ger, fatality/catastrophe reports, safety and health agency referrals, employee complaints, and media reports are also utilized to locate trenching and excavation work. Each occurrence is handled with the appropriate intervention by TOSHA.

Hazards on the Excavation Site

  • Excavation workers are exposed to many hazards, but the chief hazard is danger of cave-ins. TOSHA requires that all employees exposed to potential cave-ins be protected by sloping or benching the sides of the excava­tion, supporting the sides of the excavation, or placing a shield between the sides and the work area.
  • In addition to cave-in hazards, workers must be protected from exposure to falls, falling loads, and mobile equipment. Restraining devices, barricades, and warning systems can be used to keep objects and people from the edge of the trench.
  • Employees are prohibited from working in excavations where water has accumu­lated.
  • Where adverse atmospheric conditions may exist or develop in an excavation, the competent person must test the air and pro­vide proper controls and ensure emergency rescue equipment is readily available.
  • Safe access and egress to all excava­tions must be available.

Brief Summary of Requirements

Where a trench that is to be occupied by a worker is 5 feet deep or greater:

  • The sides of the trench must be protected from “cave-in” by one of the following:
  • Sloping (at the appropriate angle for the soil type);
  • Shoring (normally with metal and hydraulic approved equipment); or
  • Inserting a trench box in the trench;
  • Excavated dirt must not be within 2 feet of the trench;
  • Water in the bottom of the trench makes it unstable ground, so employees shall not occupy the trench unless water is being pumped out;
  • Employees in the trench must wear hard hats.
  • A ladder must be nearby (within 25 ft.) for egress from the trench; and
  • A “competent person” must be present. This person must:
  • Know the requirements of the trenching standards (29CFR1926 Subpart P) - including soil types (A, B, C); and
  • Have the authority to stop and/or make necessary changes in the operation to make it safe.

What to Do Before the Job Starts

  • Establish a safety and health program to include systematic policies, procedures and practices to protect employees from, and allow them to recognize, job-related safety and health hazards.
  • Develop safety checklists and take into account:
    Traffic
    Nearness of structures and their conditions
    Soil
    Surface and ground water
    The water table
    Overhead and underground utilities
    Weather
  • Determine the estimated location of utility installations —sewer, telephone, fuel, electric, water lines, etc.—and call Tennessee One-Call System at 1-800-351-1111 at least 3, but not more than 10, working days before digging begins.
  • Obtain and read the TOSHA standards on Trenching and Excavation (29 CFR 1926 Subpart P).
  • Obtain cooperation from supervisors, employee groups (unions), and individual employees.
  • Provide warning vests or other suitable garments, marked with or made of reflectorized or high-visibility material, to employees who are exposed to public vehicular traffic.
  • Train employees who will operate equip­ment on how to be fully alert to hazards.

For help or additional information, contact TOSHA at 1-800-249-8510 or visit the OSHA Web site at www.osha.gov.