California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 4 - Construction Safety Orders › Article 6 - Excavations › Appendix B - Sloping and Benching

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Scope and application. This appendix contains
						specifications for sloping and benching when used as methods of protecting
						employees working in excavations from cave-ins. The requirements of this
						appendix apply when the design of sloping and benching protective systems is to
						be performed in accordance with the requirements set forth in Section
						1541.1(b).
(b) Definitions.
Actual slope means the slope to which an excavation face
						is excavated.
Distress means that the soil is in a condition where a
						cave-in is imminent or is likely to occur. Distress is evidenced by such
						phenomena as the development of fissures in the face of or adjacent to an open
						excavation; the subsidence of the edge of an excavation; the slumping of
						material from the face or the bulging or heaving of material from the bottom of
						an excavation; the spalling of material from the face of an excavation; and
						ravelling, i.e., small amounts of material such as pebbles or little clumps of
						material suddenly separating from the face of an excavation and trickling or
						rolling down into the excavation.
Maximum allowable slope means the steepest incline of an
						excavation face that is acceptable for the most favorable site conditions as
						protection against cave-ins, and is expressed as the ratio of horizontal
						distance to vertical rise (H:V),
Short term exposure means a period of time less than or
						equal to 24 hours that an excavation is open.
(c) Requirements.
(1) Soil classification. Soil and rock deposits shall be
						classified in accordance with Appendix A to Section
						1541.1.
(2) Maximum allowable slope. The maximum allowable slope
						for a soil or rock deposit shall be determined from Table B-1 of this
						appendix.
(3) Actual slope.
(A) The actual slope shall not be steeper than the
						maximum allowable slope.
(B) The actual slope shall be less steep than the maximum
						allowable slope, when there are signs of distress. If that situation occurs,
						the slope shall be cut back to an actual slope which is at least ½
						horizontal to one vertical (1/2H:1V) less steep than the maximum allowable
						slope.
(C) When surcharge loads from stored material or
						equipment, operating equipment, or traffic are present, a competent person
						shall determine the degree to which the actual slope must be reduced below the
						maximum allowable slope, and shall assure that such reduction is achieved.
						Surcharge loads from adjacent structures shall be evaluated in accordance with
						Section 1541(i).
(4) Configurations. Configurations of sloping and
						benching systems shall be in accordance with Figure B-1.
TABLE B-1
MAXIMUM ALLOWABLE SLOPES
SOIL OR ROCK TYPE
MAXIMUM
								ALLOWABLE SLOPES (H:V) [1] FOR EXCAVATIONS LESS THAN 20 FEET DEEP [3]
STABLE
								ROCK
VERTICAL
(90°)
TYPE A [2]
3/4:1
(53°)
TYPE B
1:1
(45°)
TYPE C
1
								½:1
(34°)
NOTES:
1. Numbers shown in parentheses next to maximum allowable
						slopes are angles expressed in degrees from the horizontal. Angles have been
						rounded off.
2. A short-term maximum allowable slope of 1/2H:1V (63
						degrees) is allowed in excavations in Type A soil that are 12 feet or less in
						depth. Short-term maximum allowable slopes for excavations greater than 12 feet
						in depth shall be 3/4H:1V (53 degrees).
3. Sloping or benching for excavations greater than 20
						feet deep shall be designed by a registered professional engineer.
FIGURE B-1
SLOPE CONFIGURATIONS
(All slopes stated below are in the horizontal to
						vertical ratio)
B - 1.1 Excavations made in Type A soil.
1. All simple slope excavations 20 feet or less in depth
						shall gave a maximum allowable slope of 3/4:1.
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						here to view image
Simple Slope - General
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 1/2:1.
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						here to view image
Simple Slope - Short Term
2. All benched excavations 20 feet or less in depth shall
						have a maximum allowable slope of ¾ to 1 and maximum bench dimensions as
						follows:
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Simple Bench
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Multiple Bench
3. All excavations 8 feet or less in depth which have
						unsupported vertically sided lower portions shall have a maximum vertical side
						3 ½ feet.
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						here to view image
Unsupported Vertically Sided Lower Portion - Maximum 8
						Feet in Depth
All excavations more than 8 feet but not more than 12
						feet in depth with unsupported vertically sided lower portions shall have a
						maximum allowable slope of 1:1 and a maximum vertical side of 3 ½
						feet.
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						here to view image
Unsupported Vertically Sided Lower Portion - Maximum 12
						Feet in Depth
All excavations 20 feet or less in depth which have
						vertically sided lower portions that are supported or shielded shall have a
						maximum allowable slope of 3/4:1. The support or shield system must extend at
						least 18 inches above the top of the vertical side.
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						here to view image
Supported or Shielded Vertically Sided Lower
						Portion
4. All other simple slope, compound slope, and vertically
						sided lower portion excavations shall be in accordance with the other options
						permitted under 1541.1(b).
B - 1.2 Excavations Made in Type B Soil
1. All simple slope excavations 20 feet or less in depth
						shall have a maximum allowable slope of 1:1.
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						here to view image
Simple Slope
2. All benched excavations 20 feet or less in depth shall
						have a maximum allowable slope of 1:1 and maximum bench dimensions as
						follows:
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						here to view image
Single Bench
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						here to view image
Multiple Bench
3. 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. All such excavations shall
						have a maximum allowable slope of 1:1.
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						here to view image
Vertically Sided Lower Portion
4. All other sloped excavations shall be in accordance
						with the other options permitted in 1541.1(b).
B - 1.3 Excavations Made in Type C Soil
1. All simple slope excavations 20 feet or less in depth
						shall have a maximum allowable slope of 1 1/2:1.
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						here to view image
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. All such excavations shall
						have a maximum allowable slope of 1 1/2:1.
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						here to view image
Vertically Sided Lower Portion
3. All other sloped excavations shall be in accordance
						with the other options permitted in 1541.1(b).
B - 1.4 Excavations Made in Layered Soil
1. All excavations 20 feet or less in depth made in
						layered soils shall have a maximum allowable slope for each layer as set forth
						below:
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B OVER A
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C OVER A
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C OVER B
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A OVER B
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A OVER C
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B OVER C
2. All other sloped excavations shall be in accordance
						with the other options permitted in 1541.1(b).
Note: Authority cited: Section
						  142.3, Labor
						  Code. Reference: Section
						  142.3, Labor
						  Code.