OSHA Excavation Compliance
Employers, are your employees required to work in or around excavations?
Did you know the fatality rate for excavation work is 112 percent higher than the rate in general construction? Excavation and trench work operations are some of the most dangerous activities in construction. Workers are not always aware of what the hazards are and how dangerous this work can be. Falls, electrocutions, explosions, engulfment, and asphyxiation are just some of the hazards associated with excavation work that can lead to harmful and fatal incidents. These incidents are tragic, but they are also preventable.
The Occupational Safety and Health Administration (OSHA) outlines employer compliance requirements regarding excavations contained within their Construction Industry regulations, Subpart P, Excavations, 29 CFR (Code of Federal Regulations) 1926.650. One of the best additional OSHA resources for employers to reference is OSHA’s Trenching and Excavation website which emphasizes their “Slope it, Shore it, Shield it” initiative. The site is a result of OSHA conducting a two-year-long special emphasis program to raise awareness about the hazards and risks associated with trenching and excavation. The initiative is also referenced within OSHA’s publication, Protect Workers in Trenches.
Of course, before any digging into the earth begins, the estimated location of utility installations, such as sewer, telephone, fuel, electric, water lines, or any other underground installations that may reasonably be expected to be encountered during excavation work, shall be determined prior to opening an excavation. Utility companies or owners shall be contacted within established or customary local response times, advised of the proposed work, and asked to establish the location of the utility underground installations prior to the start of actual excavation. Some states have designated dialing 811 as a method for contacting local utilities.
Excavations and Trenches
OSHA defines an “excavation” and “trench” as:
Excavation- Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal.
Trench- A narrow excavation (in relation to its length) made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet (4.6 m). If forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet (4.6 m) or less (measured at the bottom of the excavation), the excavation is also considered to be a trench.
Cave-ins can occur at excavation sites for several reasons, and it can happen in an instant. Workers may be down in a trench when suddenly the trench walls collapse, burying the workers under soil. One cubic yard of soil can weigh up to 3,000 lbs. When cave-ins occur, suffocation can occur in as little as three minutes.
Before employees enter any excavation, and to determine the correct protection system to be used, understanding soil mechanics is critical. Soils are classified in one of four categories:
1. Stable rock
2. Type A (e.g., clay)
3. Type B (e.g., angular gravel, silt)
4. Type C (e.g., gravel, sand)
Instances of stable rock are rare, so contractors should be prepared to work with type A, type B, or type C. A competent person is needed to conduct an inspection and test to identify the kinds of soil involved and the properties of the soil. It is also important to keep in mind that soil conditions can and will change throughout a project due to weather conditions, movement of materials, and similar factors. As such, the competent person shall conduct daily inspections of the work site and make any necessary changes to see that work is performed in as safe a manner as possible.
OSHA’s Appendix A within Subpart P should be referenced for proper soil classification: App A - Soil Classification.
Once the soil type is verified, the next step is to determine the best protective system to be used, such as:
Sloping. This involves slanting the soil away from the trench. The degree to which the soil must be sloped will depend on the type of soil.
Benching. This process involves cutting back soil in a step-like fashion. This method should only be used for cohesive soils, and it is not an option for Type C.
Shoring. This involves using support systems such as hydraulic cylinders to create a barrier between the workers and the trench walls.
Shielding. This method uses systems such as trench boxes to protect workers from cave-ins.
Appendices B-F within Subpart P should be referenced for details on specific protective systems:
App B - Sloping and Benching
App C - Timber Shoring for Trenches
App D - Aluminum Hydraulic Shoring for Trenches
App E - Alternatives to Timber Shoring
App F - Selection of Protective Systems
Exceptions: A protection system is not required if the excavation is made entirely in stable rock; or the excavation is less than 5 feet (1.52 m) in depth and examination of the ground by a competent person provides no indication of a potential cave-in.
Whichever protective system is chosen, workers must understand that they need to stay within that system to keep themselves safe. If they go outside the confines of the systems, they are exposing themselves to potentially deadly hazards.
Excavations can also present an oxygen-deficient atmosphere, so employers must consider the probability of asphyxiation for anyone entering it. Furthermore, cases of cave-ins, depleted oxygen or toxic fumes require employers to ensure that their workers have a way to exit the excavation quickly should an incident occur. A stairway, ladder, ramp, or other safe means of egress shall be in trench excavations that are 4 feet (1.22 m) or more in depth so as to require no more than 25 feet (7.62 m) of lateral travel for employees. Additional considerations include keeping spoil piles, materials, and machinery away from the trench to avoid causing movement in the soil that could lead to a cave-in or equipment rollover.
Lastly, and despite all the best efforts for safe planning and prevention, employers must be prepared for emergency rescue. Emergency rescue equipment, such as breathing apparatus, a safety harness and line, or a basket stretcher, shall be readily available where hazardous atmospheric conditions exist or may reasonably be expected to develop during work in an excavation. This equipment shall be attended when in use. Those authorized to conduct emergency rescue must be trained and qualified to do so. Statistics show that additional injuries and fatalities occur in excavations when unqualified workers attempt emergency rescue.
And never forget about the dangers that excavations pose to the general public, which makes it critical for securing access to excavations before, during, and after work operations. Jackie’s Law, a Massachusetts law passed in 2009, was initiated by the tragic death of a four-year-old girl who became trapped in an unprotected trench in her backyard that collapsed. Employers should be aware of all federal, state, and local requirements regarding excavation safety.
When it comes to working safely within excavations, please reference and remember the following five tips spelled out within OSHA’s publication, Trenching Safety, 5 Things You Should Know to Stay Safe:
- Ensure there’s a safe way to enter and exit- 1926.651(c)
- Trenches must have cave-in protection- 1926.652(a)
- Keep materials away from the edge of the trench- 1926.651(j)
- Look for standing water or other hazards- 1926.651(h)
- Never enter a trench unless it has been properly inspected- 1926.651(k)
To better demonstrate the importance of excavation safety, review this powerful video taken years ago by an Oregon OSHA official. The official came upon a dangerous excavation site and warned workers to immediately exit the trench before it collapsed, potentially saving their lives.