How does benching protect an excavation?
Benching means a method of protecting workers 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. Benching cannot be done in Type C soil.
Does OSHA allow benching?
Short-term maximum allowable slopes for excavations greater than 12 feet (3.67 m) in depth shall be 3/4H:1V (53º). Footnote(3) Sloping or benching for excavations greater than 20 feet deep shall be designed by a registered professional engineer.
How do you bench an excavation?
As a general rule, the bottom vertical height of the trench must not exceed 4 ft for the first bench. Subsequent benches may be up to a maximum of 5 ft vertical in Type A soil and 4 ft in Type B soil to a total trench depth of 20 ft. All subsequent benches must be below the maximum allowable slope for that soil type.
How deep can an excavation be without benching?
All excavations or trenches of 4′ or greater in depth shall be appropriately benched, shored, or sloped according to the procedures and requirements set forth in OSHA’s Excavation standard, 29 CFR 1926.650, . 651, and .
Is benching allowed in Type C soil?
Type C soil is cohesive with an unconfined compressive strength of 0.5 tsf or less. Examples include granular soils such as gravel, sand and loamy sand; submerged soil or soil from which water is freely seeping; and submerged rock that is not stable. Benching Type C soil is unacceptable and shall not be done.
Can you bench Type C soil OSHA?
Appendix B does not permit an employer to bench a type C soil excavation. Therefore, it is not safe to cut steps into a slope of type C soil because the soil’s lack of cohesion is likely to cause the steps to crumble when an employee steps on them.
What type of soil Cannot be benched?
Type C soil cannot be benched.
Is it permissible to enter an excavation?
The OSHA standards prohibit employers from allowing workers to enter an excavation where water has accumulated or is accumulating unless adequate precautions are taken to protect workers.
What type of soil is benching systems are prohibited in?
Type C soil
Type C soil cannot be benched.
What type of soil should never be benched?
Examples include granular soils such as gravel, sand and loamy sand; submerged soil or soil from which water is freely seeping; and submerged rock that is not stable. Benching Type C soil is unacceptable and shall not be done.
Can I bench Type B soil?
APPENDIX B Bench Systems for TYPE B Soil For simple bench systems in TYPE B soil and trench depth of less than 20 feet, the steepest maximum allowable slope is 45 degrees from the horizontal. This translates to a 1H: 1V incline and is shown below.
What is the maximum slope for a benched excavation?
All benched excavations 20 feet or less in depth shall have a maximum allowable slope of 3/4 to 1 and maximum bench dimensions as follows: 3. All excavations 8 feet or less in depth which have unsupported vertically sided lower portions shall have a maximum vertical side of 3½ feet.
What is benching and benching?
Benching is 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. There are two basic types of benching, simple and multiple.
What are the safety measures to be taken during excavation?
Protective systems such as sloping the ground, benching the ground, shoring the trench with supports such as planking or hydraulic jacks, and shielding the trench using a trench box should be properly implemented at all times. Other excavation safety measures include:
How to ensure excavation safety for your team?
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