Type B soil may also be benched, coming up 4 feet vertically from the bottom of the excavation and 4 feet horizontally at 90-degree angles on the sides, repeating to the top of the excavation. Type B soil is cohesive with an unconfined compressive strength greater than 0.5 tsf, but less than 1.5 tsf. ...
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.
Can I cut steps into the slope of Type B soil?
If the type B soil is not cohesive soil, then the employer may be permitted to cut steps into the slope only in the extraordinary circumstance where §1926. 652 (b) permits another option for benching an excavation, such as, where a registered professional engineer approves cutting steps into the slope of type B soil under §1926. 652 (b) (4).
What is the difference between Type A and Type B soil?
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. ma ximum allowable slope is 45 degrees from the horizontal.
What is the steepest slope allowed for a bench system?
For simple bench systems in TYPE A soil and a trench depth of less than 20 feet, the steepest maximum allowable slope is 53 degrees from the horizontal. This translates to a 0.75H: 1V incline and is shown below.
What type of soil can't be benched?
Type C soilType C soil cannot be benched.
What is the ratio for benching Type B soil?
1:1 ratioType B: This soil is less stable than Type A type soil, but is very cohesive and still quite stable. The slope angle for a Type B excavation is a 1:1 ratio or a 45-degree angle. For every foot of depth, the sides of the excavation must slope back 1 foot.
Can benching be done in Type C soil?
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 is Type B soil?
Type B soil has medium unconfined compressive strength; between 0.5 and 1.5 tons per square foot. Examples of Type B soil include angular gravel, silt, silt loam, and soils that are fissured or near sources of vibration, but could otherwise be Type A.
What is the maximum allowable slope for an excavation and Type B soil?
1:1Maximum allowable slope for Type B soil is a 1:1 Height:Depth ratio / 45° Slope angle. Maximum allowable slope for Type C soil is a 1½:1 Height:Depth ratio / 34° Slope angle.
At what depth is benching required?
Sloping and Benching Sloping, benching, or other approved cave-in protection systems must be utilized in excavations 5 feet or greater in depth. For excavations greater than 20 ft depth, the slope or bench shall be designed by a registered professional engineer.
Can soils be downgraded from A to B even when it meets confined compressive strength requirements?
Soils can be downgraded from A to B even when it meets confined compressive strength requirements.
Can you shore Type C soil?
Once the competent person classifies the soil as Type C, they can't use benching or aluminum hydraulic shores (per OSHA's Appendix D) even if the soil is the better Type A or Type B.
Can you slope Class C soil?
B-1.3 Excavations Made in Type C Soil All simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 1½:1.
How do you excavate in sandy soil?
Therefore, excavation walls in sandy soil should be sheeted and shored or they should be sloped to the angle of repose, no steeper than 45 degrees, or 1 to 1. When dry, clay has high cohesive strength. When wet, it has a considerably lower cohesive strength.
Which soil type would be best for building a structure?
LoamLoam is the best soil type for construction due to its ideal combination of silt, sand, and clay. It combines the best of all their qualities into the ideal balance for supporting a foundation. Loam generally does not shift, expand, or shrink drastically and handles the presence of water very well.
What type of soil is good for construction?
Soils with good structure are more stable. Clay textures are often more stable than sand textures because they have better structure. However, a mix of particle sizes (and pore sizes) is best for engineering (just as it is best for growing crops).
How deep is a simple slope?
All simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 1½:1. SIMPLE SLOPE. 2. All excavations 20 feet or less in depth which have vertically sided lower portions shall be shielded or supported to a height at least 18 inches above the top of the vertical side.
What is the maximum slope allowed for a simple slope?
All simple slope excavation 20 feet or less in depth shall have a maximum allowable slope of ¾:1. Exception: Simple slope excavations which are open 24 hours or less (short term) and which are 12 feet or less in depth shall have a maximum allowable slope of ½:1. 2.
