Open Trenches…It’s Only a Matter of Time!
You’ll spot them everywhere – from a local utility company working in your neighborhood to your workplace at an industrial or manufacturing facility during construction. It’s way too common to see an open trench unattended and unprotected. And, as we know, it’s only a matter of time until it collapses.
More and more of our customers are asking questions to address safety-related concerns. For example, who’s signing off on the trench project? Is the person you have signing off that a trench is constructed properly and safe for entry trained to know what to look for? Do they have the authority to act (competent person), or are they assuming that the contractor is “doing the right thing”? It is all too common that supervisors are signing off on trench permits without having any trench safety training or experience. Therefore, they cannot be considered competent persons.
Of course, this is troubling. It’s troubling due to the hazards involved and the personnel who will be entering the trench. A trench collapse happens in seconds, making an escape very unlikely once the soil starts moving. Due to the weight of the soil and the speed of the collapse, most do not survive.
Trench safety starts with the Competent Person. If none are available, who is watching out for the safety of the entrants? Not just anybody will do. According to 1926.650(b), the Competent Person is “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.” Who on your site is responsible for this? Do they have the authority to correct hazards immediately?
Hopefully, we’ve convinced you of the importance of a trained and experienced Competent Person. Now, what about rescue in case the worst does happen? You’ve got an extremely hazardous situation – is your rescue service prepared for this? Your emergency response team may be trained for most emergencies, but what about this one?
Trench is one of the most dangerous rescue disciplines. It requires special knowledge, such as soil classification, hazard analysis and mitigation, understanding tabulated data, and the proper installation of shoring and shielding systems, just to name a few. It also requires specialized equipment that many response organizations simply don’t possess. This seems to be true for most municipal and industrial teams. With specialized training and equipment required for safe operations, it’s a commitment that most rescue teams just can’t make.
With trench rescue, timeliness is everything. Although it is often a slow and tedious process, proper training and equipment can be the difference between a rescue and a body recovery. Don’t ignore this hazard that may be located on your street or worksite. Take a careful look around, we think you’ll be surprised with the number of trenches and excavations that are occurring on a daily basis.
Did You Know?
After researching many of the questions we have received concerning trench operations, we came across this OSHA Letter of Interpretation that was reviewed most recently on November 8, 2018.
Note: It is always important to review all standards and regulations in their entirety.
Here are some excerpts:
1. Can workers enter a trench with water accumulation if the workers are protected from cave-in by shoring, shields or sloping, and the water level is controlled?
Paragraph .651(h) of 29 CFR 1926 allows workers to work in a trench with water accumulation, provided adequate precautions have been taken to protect employees against the hazards posed by water accumulation. The precautions necessary to comply with the standard vary with each situation, and the precautions you listed, such as additional shoring and control of the water level may not, in all cases, provide the required employee protection.
2. The Stairways and Ladders Standard requires that a stairway or ladder shall be provided at points of access where there is a break in elevation of 19 inches or more. The Excavation Standard requires a ladder or other means of access and egress when the trench is 4 feet or more. Which of these requirements is applicable to trenching operations?
Be advised that since the specific excavation standard also addresses means of access and egress, the more general requirement in the stairways and ladders subpart is not applicable. A ladder, stairway, ramp or other safe means of access is required only when the trench is four feet or more in depth. Paragraph 651(c)(2) also states…as to require no more than 25 feet (7.62 m) of lateral travel for employees.
3. Must rescue equipment be available at every trenching jobsite that is located near or passes by a gas station, refinery, gas line, sewer main, etc.? Can a contractor rely on the local rescue squad since they are probably better equipped to handle a rescue?
Emergency rescue equipment is required to be readily available where a competent person determines, based on the conditions at each jobsite, that hazardous atmospheric conditions exist or may reasonably be expected to develop during work in an excavation.
In regard to whether a contractor can rely on a local rescue squad instead of providing the rescue equipment, please be advised that many emergency situations associated with the hazards involved with hazardous atmospheres in trenches would normally require an immediate response within a few minutes or even seconds.
A rescue squad would be unable to provide the necessary response and therefore could not be used to comply with 1926.651(g)(2).
4. If a contractor has several of the same make and model trench shields at a jobsite, does he have to have separate manufacturer's tabulated data on hand for each specific shield? We have been told that the shields and the data sheets must have the same serial number in order to be in compliance.
Be advised that only one set of tabulated data is required for each different shield design. If a contractor uses several shields of the identical make and model, only one set of tabulated data would be required for them.
5. Do excavations greater than 20 feet have to be designed by an RPE (Registered Professional Engineer) or can manufacturer's tabulated data be used in lieu of an RPE? For example, a contractor may have boxes rated for depths greater than 20 feet.
Protective systems that are designed using a manufacturer's tabulated data can be used in trenches deeper than 20 feet provided the use is within the limits of the data, including depth limitations and soil type. It should be noted that all tabulated data, by definition (1926.650), must be approved by an RPE.
6. We clearly understand that a ladder has to be secured, but we are not sure how. Contractors have informed us that compliance officers have told them that they cannot secure a ladder to the shoring system or in some cases the trench shield. These same contractors have been told to secure the ladder by driving a stake into the ground and to tie the ladder off to the stake. This alternate method presents three different problems: 1) It is not always possible to drive a stake through concrete or asphalt sidewalks or pavement; 2) This method creates a tripping hazard next to the trench; 3) Some contractors believe that driving a stake could create a stress crack. Please clarify these requirements for us?
Paragraphs 1926.1053(b)(6) and (7) address ladder footing displacement which is not normally a problem in trenches. If a ladder needs to be secured against tipping, it may be secured to a shield or member of a protective structure provided the ladder does not alter the effectiveness of the protective system.
7. Does the competent person have to be standing by the trench at all times during the work shift or can he/she go off site for short periods of time, such as lunch, meeting, or maybe to pick up supplies at the local builder’s supply store? Can the competent person move around the jobsite away from the trench? Often the foreman is the competent person and he may have other responsibilities at the jobsite.
It is not normally necessary for a competent person to be at a jobsite at all times. However, it is the responsibility of a competent person to ensure compliance with applicable regulations and to make those inspections necessary to identify situations that could result in possible cave-ins, indications of failure of protective systems, hazardous atmospheres, or other hazardous conditions, and then to ensure that corrective measures are taken. Consistent with these goals, the competent person may perform other duties.
8. Must an RPE approve all work when digging below a footing, foundation, retaining wall, sidewalk or pavement? We recognize the need for an RPE to design a system to support buildings and structures. However, we don't agree that an RPE is needed to layout a system to support sidewalks, pavement, and in some cases small structures like a small retaining wall. It is often very difficult to find an RPE who is willing to take on small incidental projects.
An RPE approval is not required when the excavation is not "reasonably expected to pose a hazard to employees." In situations where it is reasonably expected to pose a hazard, an RPE approval is not required when a support system, such as underpinning, is provided to ensure the safety of employees and the stability of the structure, or the excavation is in stable rock.
9. At what point and under what conditions would OSHA consider a trench a confined space?
Under normal circumstances, a trench would not be considered a confined space. The excavation standards address the hazards associated with employees entering potentially harmful atmospheres by requiring atmospheric testing and controls where hazardous atmospheres exist or could reasonably be expected to exist.
10. Some compliance officers are telling contractors that they must use a penetrometer or shearvane to estimate the compressive strength of soil and that the thumb test is unacceptable. Keeping in mind that these are field tests. We realize that the thumb test is not accurate, but neither is the penetrometer that many compliance officers swear by. What is OSHA's interpretation for using a thumb test versus an instrument?
Be advised that the thumb penetration test is one of the acceptable methods of estimating soil compressive strength. The compressive strength can be determined by laboratory testing, or estimated in the field using a penetrometer, shearvane, thumb penetration tests, as well as by other methods.
If you’re concerned that your rescue service may not be adequately prepared, give us a call or check out these resources for more information on how to keep you and your personnel safe around trenches.
Trench Safety & Rescue Articles: Read More
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