All shoring shall be installed from the top down and removed from the bottom up. The top cylinder of hydraulic shoring shall be no more than 18 inches below the top of the excavation.
The bottom of the cylinder shall be no higher than four feet from the bottom of the excavation. Two feet of trench wall may be exposed beneath the bottom of the rail or plywood sheeting, if used. Three vertical shores, evenly spaced, must be used to form a system.
Wales are installed no more than two feet from the top, no more than four feet from the bottom, and no more than four feet apart, vertically. Inspections Frequent inspection of the excavation and surrounding area by the Competent Person is critical to ensure the safety of the workers involved in work within the trench.
An excavation inspection form is included as Appendix A in this document. The Competent Person must conduct inspections of the entire excavation site:. Temporary spoil shall be placed no closer than 2 feet from the surface edge of the excavation. The distance is measured from the nearest base of the spoil to the cut.
This distance should not be measured from the crown of the spoil deposit. This distance requirement ensures that loose rock or soil from the temporary spoil will not fall on employees in the trench. The spoil should be placed so that it channels rainwater and other run-off water away from the excavation. Spoil should be placed so that it cannot accidentally run, slide, or fall back into the excavation.
Surface Crossing of Trenches Surface crossing of trenches should not be made unless absolutely necessary. However, if necessary, they are only permitted under the following conditions:. Testing should be conducted before employees enter the trench and should be done regularly to ensure that the trench remains safe.
The frequency of testing should be increased if equipment is operating in the trench that could produce airborne contaminants. Employees required to wear respiratory protection must be trained, fit-tested, and enrolled in the UF respiratory protection program. Trenches and excavations with hazardous concentrations of airborne contaminants or oxygen deficient atmospheres qualify as confined spaces. These include atmospheres with:. Standing Water and Water Accumulation Workers must not enter or work in excavations with standing water or in which water is accumulating unless adequate protection is provided.
During rainstorms employees must exit the trench. The excavation must be carefully inspected by a competent person after each rain and before employees are permitted to re-enter the trench. Protective measures such as diversion ditches and dikes should be used to limit surface runoff water from entering the excavation. Emergencies UF personnel are not training to perform trench rescues and should not place themselves at risk in order to attempt the rescue of someone trapped due to a cave-in.
In the event of a serious injury or trapped worker requiring specialized rescue, must be called immediately. UPD should be notified after the call to While waiting for emergency response personnel to arrive, workers at the site should take measures to support the rescue team and to further protect personnel on site.
Scope and Application This program sets forth the practices required for trenches or excavations with a depth of four feet or greater along any portion of its length that will be entered by University of Florida employees or students.
This includes: On site evaluation to monitor use of safe work practices and procedures Assisting with atmospheric testing and equipment selection as needed Providing or identifying appropriate training for Competent Persons and staff Providing technical assistance as needed Reviewing and updating the program at least annually.
Departments have the primary responsibility for providing training, trench protection systems, effective barricades and supporting the use of other protective measures deemed prudent and necessary by the competent person. Supervisors have the primary responsibility for the implementation of the Trenching and Excavation Safety Policy in their work area.
The supervisor has ultimate responsibility for the safety of the employees and general public affected by the excavation. This includes evaluation of the work to be performed, determination of the means of protection that will be used and adherence to the provisions of this policy as appropriate. The supervisor must ensure daily, or more often as required, that site conditions are safe for employees to work in excavations. Employees have the primary responsibility for working in accordance with the provisions of this policy.
No employees should enter an excavation meeting the scope of this policy until authorized by the competent person. Any employee required to dig or enter an excavation shall attend, at a minimum, trenching and excavation safety awareness training prior to beginning related work. Competent person training covers the following areas in detail: Hazards related to excavation work Work practices and selection of appropriate protective systems Methods of evaluating soil and the site Inspection procedures Specific requirements of the policy and of related policies Emergency procedures Both the designated competent person and any other employee involved in trenching and excavating activities shall attend relevant health and safety training at least every two years or more often if necessary due to an observed disregard of the noted safety procedures.
A method of protecting employees from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near- vertical surfaces between levels. The separation of a mass of soil or rock material from the side of an excavation, or the loss of soil from under a trench shield or support system, and its sudden movement into the excavation, either by falling or sliding, in sufficient quantity so that it could entrap, bury, or otherwise injure and immobilize a person.
Competent Person. One who is capable to identify existing and predictable hazards in the surroundings or working conditions that may affect employees and the general public, and who has authority to take prompt corrective measures to eliminate them.
Must identify and ensure the use of adequate protective systems, work methods and personal protective equipment PPE on the excavation site. Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal.
Refers to soil that has a tendency to break along definite planes of fracture with little resistance or a material that exhibits open cracks such as tension cracks in an exposed surface.
Hazardous Atmosphere. Atmosphere that is oxygen deficient, potentially explosive, flammable, poisonous, corrosive, oxidizing, irritating, toxic or otherwise harmful in a manner that may result in death or serious injury. Protective Systems. Methods for protecting personnel working in excavations from cave-in, material falling or rolling in from the exterior or from collapse of adjacent structures. Protective systems include the use of support systems, sloping and benching systems, shield systems and other systems that provide the necessary protection.
A person who is registered as a professional engineer. Shield shield system. A structure that is able to withstand the forces imposed on it by a cave-in and thereby protect employees with the structure. Shields can be a permanent structure or can be designed to be portable and moved along as work progresses. Also known as trench boxes or trench shields. Shoring shoring system. A structure such as a metal hydraulic, mechanical or timber shoring system that supports the sides of an excavation and which is designed to prevent cave- ins.
Sloping sloping system. A method of protecting employees from cave-ins by excavating to form sides of an excavation that are inclined away from the excavation so as to prevent cave- ins. The angle of incline varies with differences in such factors as the soil type, environmental exposure conditions, and application of surcharge loads. Soil Type A. Most stable: clay, silty clay, and hardpan resists penetration.
No soil is Type A if it is fissured, is subject to vibration of any type, has previously been disturbed, or has seeping water. Soil Type B. Medium stability: silt, sandy loam, medium clay and unstable dry rock; previously disturbed soils unless otherwise classified as Type C. Soil Type C. Least stable: gravel, loamy sand, soft clay, submerged soil or dense, heavy unstable rock, and soil from which any water is seeping.
Mixed Types Layered Geological Strata — The soil must be classified on the basis of the soil classification of the weakest soil layer. Each layer may be classified individually if a more stable layer lies below a less stable layer, i. Trench trench excavation.
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 is not greater than 15 feet. If forms or other structures are installed or constructed in an excavation as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet or less, the excavation is also considered to be a trench. Dig Permit. A competent person shall be identified by name on the dig permit for all excavations with a depth of four feet or greater at any portion that personnel may enter.
Protection of the Public. Excavations must be isolated from public access by a substantial physical barrier. All temporary excavations of this type shall be backfilled as soon as possible Guardrails, fences, or barricades shall be installed around excavations adjacent to walkways, roads, paths or other traffic areas. Surface Encumbrances. All equipment, materials, supplies, buildings, roadways, trees, utility vaults, boulders, etc.
Soil Classification. The competent person in charge of the excavation shall be responsible for determining the soil type. Any one of the following will cause soil to be classified as Type C Water seepage into excavation Vibration from road traffic or equipment Signs of bulging, boiling, or sloughing Crack lines along failure zone. Manual Tests. Thumb penetration test: Attempt to press the thumb firmly into the soil in question.
If the thumb penetrates no further than the length of the nail, it is probably Type B soil. If the thumb penetrates the full length of the thumb, it is Type C. It should be noted that the thumb penetration test is the least accurate testing method. In excavations greater than 4 feet in depth a method to protect people entering the excavation from cave in must be employed.
Benching, Sloping, Shoring, and Shielding Requirements. General: Excavations under the base of the footing of a foundation or wall require a support system designed by a registered professional engineer.
Type B Soil. In Type B soil, the vertical height of the benches must not exceed 4 feet. Trench boxes or trench shields are intended to protect workers from cave-ins and similar incidents. Timber shoring shall not be used by University of Florida personnel. Frequent inspection of the excavation and surrounding area by the Competent Person is critical to ensure the safety of the workers involved in work within the trench.
The Competent Person must conduct inspections of the entire excavation site: Daily and before the start of each shift. To prevent cave-ins:. Employers should also ensure there is a safe way to enter and exit the trench. Keep materials away from the edge of the trench. Look for standing water or atmospheric hazards. Never enter a trench unless it has been properly inspected. More ». Describes how soil analysis should be conducted to determine appropriate sloping, benching, and shoring for preventing cave-ins and how employees should be trained on all trenching hazards before beginning work.
Safety and Health Topics Trenching and Excavation. Construction Resources on OSHA's construction regulations, hazard recognition, and possible solutions. Hazards and Solutions Describes how soil analysis should be conducted to determine appropriate sloping, benching, and shoring for preventing cave-ins and how employees should be trained on all trenching hazards before beginning work.
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