The primary hazard associated with excavation and trenching activities is cave-in. A cave-in may result in entrapment and eventual suffocation or workers in an unprotected excavation. Associated hazards include falls, falling loads, mobile equipment, water accumulation, hazardous atmospheres, and access and egress obstructions.
The Occupational Health and Safety Administration (OSHA) requires employers who engage in safe excavation and trenching activities to protect employees from potential hazards. This policy has been developed to assist UA Little Rock in complying with the minimum safety standards adopted by OSHA and Arkansas Department of Labor.
This policy shall serve only as a minimum for all university excavation and trenching activities performed by any department engaged in such activities, and therefore, does not prohibit additional levels of protection deemed necessary by a particular activity.
Angle of Repose. The greatest angle above the horizontal plane at which a material lies without sliding.
Benching System. A method of protecting employees from cave-in by excavating the sides of an excavation to form one or a series of horizontal steps with near-vertical surfaces between the levels.
Competent Person. One who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them. The competent person must have had specific training in and be knowledgeable of the OSHA standard: one who has not had appropriate training or does not have specific knowledge cannot be capable of identifying existing and predictable hazards in excavation work or take prompt corrective measures.
Excavation. Any man-made cut, cavity, trench, or depression in earth’s surface formed by earth removal.
Shield System. A structure (permanent or portable) designed to withstand a cave-in. These structures can be pre-manufactured or job-built in accordance with OSHA 29 CFR 1926.652(c)(3) or (c)(4). These systems are often referred to as “trench boxes” or “trench shields”.
Shoring System. A Mechanical or timber structure designed to prevent cave-in of an excavation.
Sloping System. A Method of preventing cave-in by forming sides inclined at an angle away from the excavation. The angle of incline varies with soil type.
Trench. A narrow excavation made below the surface of the ground in which the depth is greater than the width and the width does not exceed 15 feet. NOTE: For the purposes of this policy and OSHA requirements, the same requirements apply to all excavations, including trenches.
- Prior to beginning any trenching operation, all surrounding hazards must be evaluated, including the location of trees, large rocks, buildings, and sidewalks. These items should either be removed or made safe.
- Prior to digging, the location of underground utilities including telephone, electrical, sewer, water, tanks, etc, must be estimated and identified. The appropriate utility companies must be identified prior to digging. On any UA Little Rock campus, Facilities Management and Environmental Health and Safety must be notified prior to any excavation for evaluation and approval. The “Competent Person ” shall ensure that appropriate measures are taken to protect the underground installations and safeguard employees from potential hazards associated with the installation.
- Any excavation greater than four (4) feet in depth must comply with OSHA 29 CFR 1926 Subpart P and this policy.
- Excavations less than (5) feet that have been determined by the “competent person” to be safe from cave-in are not required to be shored.
- All walls and faces of excavations to which employees are exposed must be guarded by a shoring system, sloping of the ground, or other equivalent means.
- All excavations must have adequate means of egress, including steps or ladders, and must be provided within 25 feet travel distance.
- All slopes shall be excavated to the angle of repose.
- All excavations shall be sloped at an angle no steeper than 34 degrees from the horizontal as defined in OSHA Option 1, 29 CFR 1926.652(b). Steeper slopes may be used if options 2, 3, and 4 are utilized following referenced appendices in 29 CFR 1926.
- A registered professional engineer, as described in Option 4, may design excavations different from those noted in item 8 above if appropriate documentation is provided and maintained as described in 1926.652(b)(4)(ii).
- Manufacturer designed support systems may be used if that use is in accordance with the manufacturer’s tabulated data. Any uses deviating from that tabulated data must be in writing from the manufacturer and be present on the job site.
- The removal of support systems at the end of an excavation project shall be performed in a manner that will not jeopardize the safety of the workers. The removal of supports shall begin at the bottom of the excavation and progress upward simultaneously with backfilling operations.
- Prior to beginning, complete the Trenching & Excavation Checklist & Permit Form. This form contains information that should be considered prior to working in an excavation and provides documentation of the project. The form should be signed by the “Competent Person” and all workers involved with the trenching operation.
- Employees shall not be allowed to work on sloped or benched areas of excavations above other employees unless those employees at the lower level are adequately protected.
- Structural ramps and runways associated with the excavation project shall be designed by a person qualified in structural design and constructed as to design. Structures to be used for employee access only may be designed and constructed by a “Competent Person”.
- If excavation work is within 25 feet of a roadway, employees must be protected by reflective vests in addition to roadway barricades.
- All excavation sites must be adequately barricaded, using at a minimum fencing and flashing barricades on all sides in which work is not in progress. Public thoroughfares (sidewalks, common paths, etc.) shall be barricaded a minimum of ten (10) feet from the excavation work site. Any excavation greater than four (4) feet deep which is to be left unattended for greater than 24 hours, or is subject to water retention, must be fenced to a height of at least four feet using appropriate fencing materials.
- Employees may not be under loads being handled by lifting or excavation equipment.
- Employees must stand away from any vehicle being loaded or unloaded.
- Hazardous Atmospheres – Employees working in excavations which have, or have the potential of having hazardous (i.e. oxygen deficiency or toxic/flammable gases) shall be entered under procedures outlined in the “Permit Required” Confined Space Entry Policy. These procedures shall include atmospheric testing, mechanical ventilation, lifelines, respirators, and emergency rescue preparation.
- Welding operations have the potential of creating a hazardous atmosphere in an excavation. The competent person shall ensure that additional safety factors are incorporated into any welding operation by completing a “HOT WORK PERMIT” and checklist. This form shall be signed by the workers and the “Competent Person” and/or supervisor and attached to the excavation permit form. One copy shall be retained by the “Competent Person”, and one copy shall be forwarded to the UA Little Rock Environmental Health and Safety Office.
- Water Accumulation – Employees may not work in an excavation in which water has accumulated unless control devices are activated and employees are equipped with harnesses and lifelines.
- All materials and equipment must be kept at least two (2) feet from the edge of the excavation.
- All persons working within the excavation must wear a harness with a life line attached.
- The “Competent Person” must inspect the job site prior to beginning the excavation and prior to actual work within the excavation. Additionally, daily inspections must be conducted on all safety and support systems and more frequent inspections after rainfall and other unusual circumstances that may pose additional hazards for the employees.
For the purposes of this policy, the “competent person” must have a minimum of eight (8) hours (formal) initial training in the hazards of excavation and trenching operations and two (2) hours of annual training thereafter.
All workers involved with excavation and trenching operations must have a minimum of two (2) hours annual training. This training may be formal, video tape, or a combination of the two.