«Leaders Guide Trenching and Shoring Safety - Competent Person The manual for Excavations Trenching and Shoring is produced in Adobe Acrobat. The ...»
(e) The limitations of safety equipment during the performance of work;
(f) The correct procedures for equipment and materials handling and storage;
(g) Employees‘ roles Trenching and Shoring Program; and (h) The details in the specific plan.
Trenching and Shoring Training Details
Additional Trenching and Shoring training details:
(a) The company or contractor will conduct all Trenching and Shoring training.
(b) New employees should be trained with Trenching and Shoring Program in force when they are employed.
(c) All Facilities Maintenance employees will be trained in General Awareness Level Trenching and Shoring training every three years.
d) All designated Competent Persons will sign off on all safety training related to Trenching and Shoring.
(e) Any employee who has not received appropriate training in the UC Irvine Trenching and Shoring Program will not be allowed to work with Excavations until the employee has been trained and understands the program..
(f) The Trenching and Shoring Program is based on published standards and these standards are considered to be a minimum program. The UC Irvine Excavations Plan has been designed to exceed the minimum requirements.
The trainer must prepare a written certification that identifies the employee trained and the date of the training. The trainer must sign the training certification record for each employee. This certification record and training documentation are evidence of an employee receiving Trenching and Shoring training. Completion of this training equals competency in Trenching and Shoring activities.
Construction Equipment Construction, by its nature, is an ever-changing environment and involves a constant movement of personnel and materials. The use of mechanized equipment poses significant crushing and striking hazards, particularly in excavation work.
Examples of Safe Work Practices Below are some examples of safe work practices when working around mechanized
Mark off areas around the swing radius of digging equipment and move the barriers with the progress of the work. This is particularly important when the back-hoe is operating in close proximity to people, trees and other solid objects such as sections of pre-cast. Most track-type back-hoes have a serious blind-spot that‘s usually the rear of the machine on a diagonal to the operator‘s position.
Remember that loaders and backhoes are primarily earth-moving equipment.
Traveling with material suspended from buckets poses a special hazard. Swinging loads may catch a worker between the suspended load and the machinery or the worker may trip on uneven grade and be run over by the equipment.
Back-up alarms and other warning devices tend to be "tuned out" over time. In many pieces of equipment, the operators may only have a partially unobstructed vision to the rear. Still other types of equipment, such as track equipment and skid-steer loaders make it difficult for an operator to turn completely around when backing up.
Don‘t rely on back-up alarms as the sole warning of which direction a machine is going to move. Always make sure the operator is aware of your position.
You may not be working next to an active motor way, but reflective vests or clothing is still a good idea. Never assume an equipment operator can see you.
When any load is brought under tension, regardless of the equipment being used to hoist it, stay away! The load should be controlled with a tag line while aloft and only after being positioned in the location of placement should workers be anywhere near it.
No one should have any part of their body under any portion of a suspended load.
Construction equipment can present a number of hazards in and around trenching and excavation projects. Moving equipment can be a hazard to workers while traveling about the project. Vibrations transmitted by heavy equipment can weaken trench walls, causing a cave-in. Allowing a vehicle to approach too closely the edge of a trench, can cause a cave-in pulling in the vehicle and soil on top of employees.
Mobile equipment must be kept a safe distance from the edge of an excavation.
Trained employees can be posted near the edge of an excavation to help direct traffic well away from danger Depending upon the size of vehicle, load and the trench depth, it is best to keep equipment at least 10 feet or more away from the edge of a trench. If this is not possible, sloping the grade away from the excavation may help.
Note: the standard does not indicate how far to keep equipment back, so good judgment comes into play.
Hazardous Atmosphere We often take the air we breathe for granted. However, many gases in the work environment have no color or smell, and we can not tell if the air is dangerous simply by looking at it. In may go unrecognized by workers until it‘s too excavations, these late. Then workers rush in to rescue their co-workers and often become the victims as well.
Indeed, 60% of all workers who die from such atmospheres are the rescuers themselves.
The OSHA standard states that when working in trenches that are dug in locations where hazardous atmospheres are likely to be present, atmospheric testing, ventilation, and respiratory protection, must be provided. Areas such as landfills, hazardous waste sites, chemical plants, refineries, and areas where underground storage tanks are present are all locations which may produce hazardous atmospheres. Planners who perform pre-construction site surveys should look for potential atmospheric hazards as well as the physical conditions of the area to be excavated.
atmospheres contain gases or vapors in a certain concentration that can catch fire or explode if there is an ignition source.
atmospheres contain gases or vapors which, if breathed in, can make you sick, or even die. Here are a few examples of the most common sources for hazardous
atmospheres in excavations:
Oxygen deficient atmospheres:
In an open excavation, rain water passing over limestone, causes an acidity reaction, and in turn produces carbon dioxide. Carbon dioxide is a simple asphyxiant which replaces oxygen in the air we breathe and can result in death. Landfill gases can displace oxygen.
Volatile organic compounds found in petroleum products can move through small spaces in soils and accumulate in excavations. This can create both a fire and toxic hazard. Buried tanks next to an excavation site are a common source of these compounds as well as leaking gas mains and services.
Another common flammable gas is Methane. Methane occurs naturally from the breakdown of organic materials, such as sewage, leaves or weeds.
Carbon monoxide from vehicles or equipment too near the excavation can accumulate and create a toxic environment for the workers.
When dealing with potential hazardous environments, early recognition is very important.
Years ago, miners had to rely on canaries to tell them if the air they were breathing was hazardous. In today‘s world, testing equipment for atmospheric hazards are compact and easy to use. One instrument can be purchased to detect the three most common atmospheric hazards found in excavation.
should understand and uses these direct reading instrument(s) that can detect the most common atmospheric hazards found in excavations. Continuous air monitoring is always a good idea because of changing conditions that can occur at a construction site.
In certain cases, an excavation may have the potential to contain hazardous atmospheres.
Confined Spaces Before any work is attempted in confined spaces, all employees must be thoroughly trained in all aspects of the standard and safe work practices of confined space entry. No employee may be allowed to work or enter with out training and understanding of Confined Space hazards.
Table 1 More Examples of Confined Spaces Cal/OSHA defines a Confined Space in Article 108 of Title 8 of the General Industry Safety Orders, Sections 5156 - 5159 adopted October 21, 1993.
Conditions for a Confined Space
A Confined Space means a space that:
1) Is large enough and so configured that an employee can bodily enter and perform assigned work; and
2) Has limited or restricted means for entry or exit (for example: tanks, vessels, silos, storage bins, hoppers, vaults and pits are spaces that may have limited means of entry);
3) Is not designed for continuous employee occupancy.
Confined Space Defined Section 5158 defines a Confined Space by the concurrent existence of the following
A) Existing ventilation is insufficient to remove dangerous air contamination and/or oxygen deficiency with may exist or develop.
B) Ready access or egress for removal of a suddenly disabled employee is difficult due to the location and/or size of the opening(s).
Where oxygen deficiency or a hazardous atmosphere exists or could reasonably be expected to exist, such excavations such as in landfills and where hazardous substances are stored nearby, the atmospheres must be tested before employees enter excavations greater than 4 feet in depth.
Adequate precaution must be taken to provide ventilation, to prevent employee exposure to an atmosphere containing a concentration in excess of 10% of the lower flammable limit of that gas.
When engineering controls such as ventilation is employed to reduce contaminants to a safe level, re-testing must be conducted periodically to assure the atmosphere remains safe.
Specialized confined space training, assignment of an entry supervisor, emergency standby by and emergency rescue equipment such as SCBA's, safety harnesses and life line or basket stretcher must be readily available where atmospheric hazards exists or may be reasonably expected to exist or develop during excavation work.
Should employees have to enter bell-bottom pier holes or similar deep footing excavations, the workers must wear a safety harness, with life line attached as called for in the Confined Space Safety Standard. The life line may not have any other purpose other than rescue, such as tool and equipment transfer.
Where hazardous atmospheres may be present, the excavation must be tested in accordance with Confined Space Safety Standards.
A minimum of 19.5% oxygen and safe levels of Carbon Monoxide, Hydrogen Sulfide, Combustibles or other hazardous atmospheres are required to work safely in excavations which may become a confined space.
TESTS MUST BE CONDUCTED TO ASSURE THAT THE ATMOSPHERE IS NOT:
Any time fuel powers equipment or cutting or welding is performed in any excavation; the atmosphere must be monitored and augmented by ventilation. If a confined space condition exists all the provisions of the Confined Space Safety Standards are required to be followed.
Overhead Loads No employee should be permitted under loads handled by lifting or digging equipment. It is recommended that loads which need personal control be directed by the use of ropes or poles from a safe distance.
Under no circumstances are employees allowed to work under an overhead load. When a vehicle such as a dump truck is depositing or picking up a load, employees are required to stand away from the vehicle to avoid being struck or buried by spilled or falling materials.
Employees have been killed when the material dropped by a dump truck buried them or the weight of the vehicle and load collapsed the trench.
Employees may not work in an excavation where water has or is accumulating unless adequate steps have been taken to de-water and properly support the trench walls. Methods
of water control may include but not be limited to:
• Water removal pumps • Well points
Water accumulation and removal must be supervised, monitored and inspected by the job site Competent Person to assure proper operation and water control is effective.
Heavy rain will require more frequent inspection and controls to assure safety.
If work interrupts natural drainage or water courses such as streams etc, methods to divert the water must be applied such as the use of ditches, dikes, etc. to prevent water from entering the work area.
In certain circumstances extra safety precautions may include but not be limited to special supports, well points, and use of a safety harness, lifeline and personal floatation device.
Adjacent Structures Excavations which may affect the stability of any adjacent structure such as a building, wall, sidewalk, telephone pole, concrete conduits, undermined pavement, etc. will require additional support systems such as shoring, underpinning or bracing to ensure stability.
Employees must never be allowed to work below the base or level of the footing or
foundation of any excavation - except:
Where a support system has been installed to provide structural stability and safety for the employees, or The excavation is in stable rock; or A registered professional engineer has determined that such work will not pose a hazard to employees Protection from Loose Rock Employees working in excavations must be protected from the hazard of loose rock and soil falling from the face of a trench wall. Loose material must be controlled by scaling the sides of the trench to remove loose material or installation of plywood to help contain loose material.
Note: Plywood is only intended to prevent unraveling of loose material, the plywood must be a minimum of 3/4 inch material meeting OSHA specifications for this purpose.
Excavated material and equipment must be kept at least 2 feet from the edge of a 5‘ trench.
A clear pathway must be maintained at all times to: