Is benching allowed in Type C soil?

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 I bench Type B soil?

Footnote(3) Sloping or benching for excavations greater than 20 feet deep shall be designed by a registered professional engineer. B-1.1 Excavations made in Type A soil. All simple slope excavation 20 feet or less in depth shall have a maximum allowable slope of ¾:1.

Can Type A and B soils be sloped or benched?

TYPE B soil is not as stable as TYPE A. and the incline for the sloped system is not as great as it would be for TYPE A soils. For TYPE B soil and a trench depth of less than 20 feet, the steepest maximum allowable slope is 45 degrees from the horizontal.

What are the OSHA soil types?

OSHA classifies soils into four categories: Solid Rock, Type A, Type B, and Type C. Solid Rock is the most stable, and Type C soil is the least stable. Soils are typed not only by how cohesive they are, but also by the conditions in which they are found.

What is soil benching?

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.

What is unsuitable soil?

unsuitable soil is soil that will not allow building construction with conventional foundation systems or ratings.

What is OSHA Type C soil?

Type C Soils are cohesive soils with an unconfined compressive strength of 0.5 tsf (48 kPa) or less. Other Type C soils include granular soils such as gravel, sand and loamy sand, submerged soil, soil from which water is freely seeping, and submerged rock that is not stable.

What is benching in road construction?

The art of cutting side slopes in steps is called benching. When the embankment is constructed on hillside slopes, it is necessary to bench the surface of the hill slope to add stability to the slope. Thus benching reduces the probability of sides of slopes. …

What are unsuitable materials called?

Unsuitable material means other than suitable material and shall comprise:▪ material from swamps, marshes and bogs;▪ logs, stumps and perishable materials;▪ material susceptible to spontaneous combustion; and▪ Clay of liquid limit exceeding ninety (90) and/or plasticity index exceeding sixty-five (65).

Can You bench a Type C soil excavation?

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 is the OSHA rule for Type C soil?

OSHA requires type C soil to be sloped at 1½H:1V and it cannot be benched. This means that the slope must be cut back 1½ ft horizontally for every 1 ft of depth. The 1½:1 is equal to an angle of 34 degrees from the horizontal.

What are the OSHA requirements for trench protection?

It is an OSHA requirement that all workers in trenches 5 ft or more in depth (some states 4 ft deep) must be protected by a trench protective system (sloping, shoring and shields). I doubt there is an underground contractor that does not realize the importance of protecting workers from a cave-in when employees are working in a trench.

What is the maximum allowable slope for Type A soil?

Footnote (1) Numbers shown in parentheses next to maximum allowable slopes are angles expressed in degrees from the horizontal. Angles have been rounded off. Footnote (2) A short-term maximum allowable slope of 1/2H:1V (63º) is allowed in excavations in Type A soil that are 12 feet (3.67 m) or less in depth.