29 Cfr 1926.652

Occupational Safety and Health Admin., Labor
expected to pose a hazard to employees
shall not be permitted except when:
(i) A support system, such as underpinning, is provided to ensure the safety of employees and the stability of the
structure; or
(ii) The excavation is in stable rock;
or
(iii) A registered professional engineer has approved the determination
that the structure is sufficently removed from the excavation so as to be
unaffected by the excavation activity;
or
(iv) A registered professional engineer has approved the determination
that such excavation work will not
pose a hazard to employees.
(3) Sidewalks, pavements, and appurtenant structure shall not be undermined unless a support system or another method of protection is provided
to protect employees from the possible
collapse of such structures.
(j) Protection of employees from loose
rock or soil. (1) Adequate protection
shall be provided to protect employees
from loose rock or soil that could pose
a hazard by falling or rolling from an
excavation face. Such protection shall
consist of scaling to remove loose material; installation of protective barricades at intervals as necessary on the
face to stop and contain falling material; or other means that provide equivalent protection.
(2) Employees shall be protected from
excavated or other materials or equipment that could pose a hazard by falling or rolling into excavations. Protection shall be provided by placing and
keeping such materials or equipment
at least 2 feet (.61 m) from the edge of
excavations, or by the use of retaining
devices that are sufficient to prevent
materials or equipment from falling or
rolling into excavations, or by a combination of both if necessary.
(k) Inspections. (1) Daily inspections
of excavations, the adjacent areas, and
protective systems shall be made by a
competent person for evidence of a situation that could result in possible
cave-ins, indications of failure of protective
systems,
hazardous
atmospheres, or other hazardous conditions. An inspection shall be conducted
by the competent person prior to the
start of work and as needed throughout

§ 1926.652

the shift. Inspections shall also be
made after every rainstorm or other
hazard increasing occurrence. These inspections are only required when employee exposure can be reasonably anticipated.
(2) Where the competent person finds
evidence of a situation that could result in a possible cave-in, indications
of failure of protective systems, hazardous atmospheres, or other hazardous conditions, exposed employees
shall be removed from the hazardous
area until the necessary precautions
have been taken to ensure their safety.
(l) Walkways shall be provided where
employees or equipment are required
or permitted to cross over excavations.
Guardrails
which
comply
with
§ 1926.502(b) shall be provided where
walkways are 6 feet (1.8 m) or more
above lower levels.
[54 FR 45959, Oct. 31, 1989, as amended by 59
FR 40730, Aug. 9, 1994]

§ 1926.652 Requirements for protective
systems.
(a) Protection of employees in excavations. (1) Each employee in an excavation shall be protected from cave-ins
by an adequate protective system designed in accordance with paragraph
(b) or (c) of this section except when:
(i) Excavations are made entirely in
stable rock; or
(ii) Excavations are less than 5 feet
(1.52m) in depth and examination of the
ground by a competent person provides
no indication of a potential cave-in.
(2) Protective systems shall have the
capacity to resist without failure all
loads that are intended or could reasonably be expected to be applied or
transmitted to the system.
(b) Design of sloping and benching systems. The slopes and configurations of
sloping and benching systems shall be
selected and constructed by the employer or his designee and shall be in
accordance with the requirements of
paragraph (b)(1); or, in the alternative,
paragraph (b)(2); or, in the alternative,
paragraph (b)(3), or, in the alternative,
paragraph (b)(4), as follows:
(1) Option (1)—Allowable configurations
and slopes. (i) Excavations shall be
sloped at an angle not steeper than one
and one-half horizontal to one vertical

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§ 1926.652

29 CFR Ch. XVII (7–1–10 Edition)

(34 degrees measured from the horizontal), unless the employer uses one
of the other options listed below.
(ii) Slopes specified in paragraph
(b)(1)(i) of this section, shall be excavated to form configurations that are
in accordance with the slopes shown
for Type C soil in Appendix B to this
subpart.
(2) Option (2)—Determination of slopes
and configurations using Appendices A
and B. Maximum allowable slopes, and
allowable configurations for sloping
and benching systems, shall be determined in accordance with the conditions and requirements set forth in appendices A and B to this subpart.
(3) Option (3)—Designs using other tabulated data. (i) Designs of sloping or
benching systems shall be selected
from and be in accordance with tabulated data, such as tables and charts.
(ii) The tabulated data shall be in
written form and shall include all of
the following:
(A) Identification of the parameters
that affect the selection of a sloping or
benching system drawn from such data;
(B) Identification of the limits of use
of the data, to include the magnitude
and configuration of slopes determined
to be safe;
(C) Explanatory information as may
be necessary to aid the user in making
a correct selection of a protective system from the data.
(iii) At least one copy of the tabulated data which identifies the registered professional engineer who approved the data, shall be maintained at
the jobsite during construction of the
protective system. After that time the
data may be stored off the jobsite, but
a copy of the data shall be made available to the Secretary upon request.
(4) Option (4)—Design by a registered
professional engineer. (i) Sloping and
benching systems not utilizing Option
(1) or Option (2) or Option (3) under
paragraph (b) of this section shall be
approved by a registered professional
engineer.
(ii) Designs shall be in written form
and shall include at least the following:
(A) The magnitude of the slopes that
were determined to be safe for the particular project;

(B) The configurations that were determined to be safe for the particular
project; and
(C) The identity of the registered professional engineer approving the design.
(iii) At least one copy of the design
shall be maintained at the jobsite
while the slope is being constructed.
After that time the design need not be
at the jobsite, but a copy shall be made
available to the Secretary upon request.
(c) Design of support systems, shield
systems, and other protective systems. Designs of support systems shield systems, and other protective systems
shall be selected and constructed by
the employer or his designee and shall
be in accordance with the requirements
of paragraph (c)(1); or, in the alternative, paragraph (c)(2); or, in the alternative, paragraph (c)(3); or, in the
alternative, paragraph (c)(4) as follows:
(1) Option (1)—Designs using appendices A, C and D. Designs for timber
shoring in trenches shall be determined
in accordance with the conditions and
requirements set forth in appendices A
and C to this subpart. Designs for aluminum hydraulic shoring shall be in
accordance with paragraph (c)(2) of this
section, but if manufacturer’s tabulated data cannot be utilized, designs
shall be in accordance with appendix D.
(2) Option (2)—Designs Using Manufacturer’s Tabulated Data. (i) Design of support systems, shield systems, or other
protective systems that are drawn
from manufacturer’s tabulated data
shall be in accordance with all specifications, recommendations, and limitations issued or made by the manufacturer.
(ii) Deviation from the specifications,
recommendations,
and
limitations
issued or made by the manufacturer
shall only be allowed after the manufacturer issues specific written approval.
(iii) Manufacturer’s specifications,
recommendations, and limitations, and
manufacturer’s approval to deviate
from the specifications, recommendations, and limitations shall be in written form at the jobsite during construction of the protective system.
After that time this data may be
stored off the jobsite, but a copy shall

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Occupational Safety and Health Admin., Labor
be made available to the Secretary
upon request.
(3) Option (3)—Designs using other tabulated data. (i) Designs of support systems, shield systems, or other protective systems shall be selected from and
be in accordance with tabulated data,
such as tables and charts.
(ii) The tabulated data shall be in
written form and include all of the following:
(A) Identification of the parameters
that affect the selection of a protective
system drawn from such data;
(B) Identification of the limits of use
of the data;
(C) Explanatory information as may
be necessary to aid the user in making
a correct selection of a protective system from the data.
(iii) At least one copy of the tabulated data, which identifies the registered professional engineer who approved the data, shall be maintained at
the jobsite during construction of the
protective system. After that time the
data may be stored off the jobsite, but
a copy of the data shall be made available to the Secretary upon request.
(4) Option (4)—Design by a registered
professional engineer. (i) Support systems, shield systems, and other protective systems not utilizing Option 1, Option 2 or Option 3, above, shall be approved by a registered professional engineer.
(ii) Designs shall be in written form
and shall include the following:
(A) A plan indicating the sizes, types,
and configurations of the materials to
be used in the protective system; and
(B) The identity of the registered
professional engineer approving the design.
(iii) At least one copy of the design
shall be maintained at the jobsite during construction of the protective system. After that time, the design may
be stored off the jobsite, but a copy of
the design shall be made available to
the Secretary upon request.
(d) Materials and equipment. (1) Materials and equipment used for protective
systems shall be free from damage or
defects that might impair their proper
function.
(2) Manufactured materials and
equipment used for protective systems
shall be used and maintained in a man-

§ 1926.652

ner that is consistent with the recommendations of the manufacturer,
and in a manner that will prevent employee exposure to hazards.
(3) When material or equipment that
is used for protective systems is damaged, a competent person shall examine the material or equipment and
evaluate its suitability for continued
use. If the competent person cannot assure the material or equipment is able
to support the intended loads or is otherwise suitable for safe use, then such
material or equipment shall be removed from service, and shall be evaluated and approved by a registered professional engineer before being returned to service.
(e) Installation and removal of support—(1) General. (i) Members of support systems shall be securely connected together to prevent sliding, falling, kickouts, or other predictable failure.
(ii) Support systems shall be installed and removed in a manner that
protects employees from cave-ins,
structural collapses, or from being
struck by members of the support system.
(iii) Individual members of support
systems shall not be subjected to loads
exceeding those which those members
were designed to withstand.
(iv) Before temporary removal of individual members begins, additional
precautions shall be taken to ensure
the safety of employees, such as installing other structural members to
carry the loads imposed on the support
system.
(v) Removal shall begin at, and
progress from, the bottom of the excavation. Members shall be released slowly so as to note any indication of possible failure of the remaining members
of the structure or possible cave-in of
the sides of the excavation.
(vi) Backfilling shall progress together with the removal of support systems from excavations.
(2) Additional requirements for support
systems for trench excavations. (i) Excavation of material to a level no greater
than 2 feet (.61 m) below the bottom of
the members of a support system shall
be permitted, but only if the system is
designed to resist the forces calculated
for the full depth of the trench, and

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Pt. 1926, Subpt. P, App. A

29 CFR Ch. XVII (7–1–10 Edition)

there are no indications while the
trench is open of a possible loss of soil
from behind or below the bottom of the
support system.
(ii) Installation of a support system
shall be closely coordinated with the
excavation of trenches.
(f) Sloping and benching systems. Employees shall not be permitted to work
on the faces of sloped or benched excavations at levels above other employees except when employees at the lower
levels are adequately protected from
the hazard of falling, rolling, or sliding
material or equipment.
(g) Shield systems—(1) General. (i)
Shield systems shall not be subjected
to loads exceeding those which the system was designed to withstand.
(ii) Shields shall be installed in a
manner to restrict lateral or other hazardous movement of the shield in the
event of the application of sudden lateral loads.
(iii) Employees shall be protected
from the hazard of cave-ins when entering or exiting the areas protected by
shields.
(iv) Employees shall not be allowed
in shields when shields are being installed, removed, or moved vertically.
(2) Additional requirement for shield
systems used in trench excavations. Excavations of earth material to a level not
greater than 2 feet (.61 m) below the
bottom of a shield shall be permitted,
but only if the shield is designed to resist the forces calculated for the full
depth of the trench, and there are no
indications while the trench is open of
a possible loss of soil from behind or
below the bottom of the shield.
APPENDIX A TO SUBPART P OF PART
1926—SOIL CLASSIFICATION
(a) Scope and application—(1) Scope. This
appendix describes a method of classifying
soil and rock deposits based on site and environmental conditions, and on the structure
and composition of the earth deposits. The
appendix contains definitions, sets forth requirements, and describes acceptable visual
and manual tests for use in classifying soils.
(2) Application. This appendix applies when
a sloping or benching system is designed in
accordance with the requirements set forth
in § 1926.652(b)(2) as a method of protection
for employees from cave-ins. This appendix
also applies when timber shoring for excavations is designed as a method of protection
from cave-ins in accordance with appendix C

to subpart P of part 1926, and when aluminum hydraulic shoring is designed in accordance with appendix D. This Appendix
also applies if other protective systems are
designed and selected for use from data prepared in accordance with the requirements
set forth in § 1926.652(c), and the use of the
data is predicated on the use of the soil classification system set forth in this appendix.
(b) Definitions. The definitions and examples given below are based on, in whole or in
part, the following: American Society for
Testing Materials (ASTM) Standards D653–85
and D2488; The Unified Soils Classification
System, The U.S. Department of Agriculture
(USDA) Textural Classification Scheme; and
The National Bureau of Standards Report
BSS–121.
Cemented soil means a soil in which the particles are held together by a chemical agent,
such as calcium carbonate, such that a handsize sample cannot be crushed into powder or
individual soil particles by finger pressure.
Cohesive soil means clay (fine grained soil),
or soil with a high clay content, which has
cohesive strength. Cohesive soil does not
crumble, can be excavated with vertical
sideslopes, and is plastic when moist. Cohesive soil is hard to break up when dry, and
exhibits significant cohesion when submerged. Cohesive soils include clayey silt,
sandy clay, silty clay, clay and organic clay.
Dry soil means soil that does not exhibit
visible signs of moisture content.
Fissured means a soil material 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.
Granular soil means gravel, sand, or silt,
(coarse grained soil) with little or no clay
content. Granular soil has no cohesive
strength. Some moist granular soils exhibit
apparent cohesion. Granular soil cannot be
molded when moist and crumbles easily
when dry.
Layered system means two or more distinctly different soil or rock types arranged
in layers. Micaceous seams or weakened
planes in rock or shale are considered layered.
Moist soil means a condition in which a soil
looks and feels damp. Moist cohesive soil can
easily be shaped into a ball and rolled into
small diameter threads before crumbling.
Moist granular soil that contains some cohesive material will exhibit signs of cohesion
between particles.
Plastic means a property of a soil which allows the soil to be deformed or molded without cracking, or appreciable volume change.
Saturated soil means a soil in which the
voids are filled with water. Saturation does
not require flow. Saturation, or near saturation, is necessary for the proper use of instruments such as a pocket penetrometer or
sheer vane.

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