DEPARTMENT OF LABOR AND ECONOMIC OPPORTUNITY

DIRECTOR'S OFFICE

CONSTRUCTION SAFETY AND HEALTH STANDARD

Filed with the secretary of state on December 27, 2023

These rules take effect immediately after filing with the secretary of state unless adopted

under section 33, 44, or 45a(9) of the administrative procedures act of 1969, 1969 PA

306, MCL 24.233, 24.244, or 24.245a. Rules adopted under these sections become

effective 7 days after filing with the secretary of state.

(By authority conferred on the director of the department of labor and economic

opportunity by sections 19 and 21 of the Michigan occupational safety and health act,

1974 PA 154, MCL 408.1019 and 408.1021, and Executive Reorganization Order Nos.

1996-2, 2003-1, 2008-4, 2011-4, and 2019-3, MCL 445.2001, 445.2011, 445.2025,

445.2030, and 125.1998)

R 408.40901, R 408.40925, R 408.40926, R 408.40927, R 408.40932, R 408.40933, R

408.40941, R 408.40942, R 408.40943, R 408.40945, R 408.40951, and R 408.40953 of

the Michigan Administrative Code are amended, as follows:

PART 9, EXCAVATION, TRENCHING, AND SHORING

R 408.40901 Scope and referenced standards.

Rule 901. (1) This part pertains to the digging of excavations and trenches which an

employee is required to enter and the supporting systems used on construction

operations.

(2) The following Michigan occupational safety and health (MIOSHA) standards are

referenced in these rules:

(a) Construction Safety and Health Standard Part 21. “Guarding of Walking and

Working Areas,” R 408.42101 to R 408.42160.

(b) Construction Safety Standard Part 45. “Fall Protection,” R 408.44501 to R

408.44502.

(3) Up to 5 copies of the standards listed in subrule (2) of this rule may be obtained at

no charge from the Department of Labor and Economic Opportunity, MIOSHA,

Standards and FOIA Section, 530 West Allegan Street, P.O. Box 30645, Lansing,

Michigan, 48909-8145 or via the internet at the following website:

www.michigan.gov/mioshastandards. For quantities greater than 5, the cost, as of the time

of adoption of these rules, is 4 cents per page.

R 408.40925 Definitions A to Q.

Rule 925. (1) "Angle of repose" means the maximum permissible slope as determined

by table 1.

October 9, 2023

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(2) “Benching” means a method of protecting employees from cave-ins by excavating

the sides of an excavation to form 1 or a series of horizontal levels or steps, usually with

vertical or near-vertical surfaces between levels.

(3) "Braces" or "struts" means the horizontal cross members of a shoring system that

bear against the uprights or stringers.

(4) “Cave-in” means the separation of a mass of soil or rock material from the side of an

excavation, or the loss of soil from under a trench shield or support system, and its sudden

movement into the excavation, either by falling or sliding, in sufficient quantity so that it

could entrap, bury, or otherwise injure and immobilize a person.

(5) “Competent person” means an individual who is capable of identifying existing and

predictable hazards in the surroundings or working conditions which are unsanitary,

hazardous, or dangerous to employees, and who has authorization to take prompt

corrective measures to eliminate them.

(6) "Excavation" means any man-made cut, cavity, trench, or depression in the earth's

surface, including its sides, walls, or faces, formed by earth removal.

(7) "Hazardous atmosphere" means an atmosphere which by reason of being any of

the following, may cause death, illness, or injury:

(a) Explosive.

(b) Flammable.

(c) Poisonous.

(d) Corrosive.

(e) Oxidizing.

(f) Irritating.

(g) Oxygen deficient.

(h) Toxic.

(i) Otherwise harmful.

(8) "Kickout" means the accidental release or failure of a stringer or brace.

(9) “Protective system” means a method of protecting employees from cave-ins, from

material that could fall or roll from an excavation face or into an excavation, or from the

collapse of adjacent structures. Protective systems include support systems, sloping and

benching systems, shield systems, and other systems that provide the necessary

protection.

(10) "Qualified person" means an individual who, by possession of a recognized degree

or certificate of professional standing, or who, by extensive knowledge, training, and

experience, has successfully demonstrated the ability to solve or resolve problems relating

to the subject matter and work.

(11) “Ramp” means an inclined walking or working surface that is used to gain access

to 1 point from another and is constructed from earth or from structural materials such as

steel or wood.

(12) “Registered professional engineer” means a person who is registered as a

professional engineer in the state where the work is to be performed. However, a

professional engineer, registered in any state is deemed to be a registered professional

engineer within the meaning of this standard when approving designs for manufactured

protective systems or tabulated data to be used in interstate commerce.

R 408.40926 Definitions; S.

Rule 926. (1) “Sheeting” means the members of a shoring system that retain the earth

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in position and in turn are supported by other members of the shoring system.

(2) "Sheet piling" means a continuous row of timber or steel piles driven in close contact

to provide a tight wall to resist lateral pressure of water, adjacent earth, or other materials.

(3) “Shield” or “shield system” means a structure that is able to withstand the forces

imposed on it by a cave-in and thereby protect employees within the structure. Shields

can be permanent structures or can be designed to be portable and moved along as work

progresses. Additionally, shields can be either premanufactured or job-built in accordance

with R 408.40932, R 408.40942, R 408.40943, R 408.40945, and R 408.40953. Shields

used in trenches are usually referred to as trench boxes or trench shields.

(4) “Shoring” or “shoring system” means a structure such as a metal hydraulic,

mechanical, or timber shoring system that supports the sides of an excavation and which

is designed to prevent cave-ins.

(5) "Sides" sometimes called faces or walls, mean the vertical or inclined earth surfaces

formed as a result of excavation work.

(6) "Slope" means the acute angle formed by the side of a trench or excavation and

the horizontal plane.

(7) "Soil" means any of the following:

(a) "Clay" means a very fine textured soil that derives its resistance to displacement

from cohesion and may be:

(i) "Soft clay" means a clay-type soil that has an unconfined strength of less than 1.0

ton per square foot.

(ii) "Medium clay" or "plastic" means a clay-type soil that has a minimum unconfined

strength of 1.0 ton per square foot.

(iii) "Firm soil" means a clay-type soil that is resistant to forces causing rupture or

displacement. A firm clay has a minimum unconfined strength of 1.5 tons per square

foot.

(iv) "Stiff clay" means a clay-type soil that is very resistant to forces causing rupture

or displacement. A stiff clay has a minimum unconfined strength of 2.5 tons per square

foot.

(b) "Fill" means a manmade soil condition that may be constructed of any type of soil

or combination thereof.

(c) "Granular soil" means a coarse grained soil that does not possess cohesion but

derives its strength from internal friction.

(d) "Organic soil" means a soil that contains significant amounts of peat, muck, or marl.

(e) "Running soil" means any type of soil that has insufficient strength to stand

unsupported. Running soil tends to run or slough into the excavation as the excavation is

being dug.

(8) "Stringers" mean the horizontal members of a trench shoring system whose sides

bear against the uprights or earth.

(9) “Structural ramp” means a ramp built of steel or wood, usually used for vehicle

access. Ramps made of soil or rock are not considered structural ramps.

(10) “Support system” means a structure such as underpinning, bracing, or shoring,

which provides support to an adjacent structure, underground installation, or the sides of

an excavation.

R 408.40927 Definitions; T, U.

Rule 927. (1) “Tabulated data” means tables and charts approved by a registered

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professional engineer and used to design and construct a protective system.

(2) "Toe of slope" means the point at which the side of an excavation intersects the

lowest level of the excavation.

(3) "Trench" means an excavation having a depth greater than its width measured at

the bottom.

(4) "Trench jack" means a screw or hydraulic jack used as a brace in a trench shoring

system.

(5) "Trench shield," sometimes called a trench box, means a trench shoring system

composed of steel plates and bracing, welded or bolted together, which can be moved

along as work progresses.

(6) "Uprights" mean the vertical members of a trench shoring system.

R 408.40932 Excavation; consideration of soil types; water; slide hazards.

Rule 932. (1) If different textured soils are encountered in the side of an excavation,

each soil type of the excavation shall be cut to the proper angle of repose, except that the

slope shall not steepen between the toe of the slope and the ground level where soft clay

or running soil is encountered in the lower cut.

(2) An employee shall not work in an excavation in which there is accumulated water or

in which water is accumulating unless precautions have been taken to protect employees

against the hazards posed by water accumulation. The precautions necessary to protect

employees adequately vary with each situation, but may include special supportor shield

systems to protect from cave-ins, water removal to control the level of accumulating

water, or the use of a safety harness and lifeline.

(3) If water is controlled or prevented from accumulating by the use of water removal

equipment, the water removal equipment and operation shall be monitored by a competent

person or a monitoring system to ensure that the equipment is properly operated.

(4) An ongoing inspection of an excavation or trench shall be made by a competent

person. After every rainstorm or other hazard-producing occurrence, an inspection shall

be made by a competent person for evidence of possible slides or cave-ins. Where these

conditions are found, all work shall cease until additional precautions, such as additional

shoring or reducing the slope, have been accomplished.

(5) When installed forms, walls, or similar structures create a trench between the form,

wall, or structure and the side of the excavation, an employer shall comply with the

provisions of R 408.40941 to R 408.40944.

R 408.40933 Excavation; obstructions; retaining materials; egress; guarding; heavy

equipment.

Rule 933. (1) A tree, boulder, rock fragment, or other obstruction whose movement

could cause injury to an employee shall be removed or supported.

(2) An excavation that an employee is required to enter shall have excavated and other

material stored and retained not less than 2 feet from the excavation edge.

(3) When mobile equipment is utilized or permitted adjacent to an excavation where the

operator’s vision is restricted, stop logs or barricades shall be utilized or a signal person

shall be used.

(4) An excavation 48 or more inches in depth and occupied by an employee shall be

provided with either a ladder extending not less than 3 feet above the top as a means of

access or with a ramp meeting the requirements of subrule (5) of this rule. Lateral travel

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along the wall of a trench to a ladder or other means of egress shall not exceed 25 feet.

(5) An earth ramp may be used in place of a ladder if it meets all of the following

requirements:

(a) The ramp material shall be stable.

(b) The sides of the excavation above the ramp shall be maintained to the angle of

repose or sheeted or shored along the means of egress.

(c) The degree of angle of the ramp shall not be more than 45 degrees.

(d) Vertical height between the floor of the trench and the toe of the ramp shall

not exceed 30 inches.

(6) Structural ramps that are used solely by employees as a means of access or egress

from excavations shall be designed by a competent person. Structural ramps used for

access or egress of equipment shall be designed by a competent person qualified in

structural design and shall be constructed in accordance with the design.

(7) Ramps and runways constructed of 2 or more structural members shall have the

structural members connected together to prevent displacement.

(8) Structural members used for ramps and runways shall be of uniform thickness.

(9) Cleats or other appropriate means used to connect runway structural members shall

be attached to the bottom of the runway or shall be attached in a manner to prevent

tripping.

(10) Structural ramps used in lieu of steps shall be provided with cleats or other surface

treatments on the top surface to prevent slipping.

R 408.40941 Excavation; angle of repose.

Rule 941. (1) The side of an excavation more than 5 feet deep shall be sloped as

prescribed in table 1, unless supported as prescribed in this part.

(2) An excavation less than 5 feet in depth shall also be effectively protected when

examination of the ground indicates hazardous earth movement may be expected.

TABLE 1

MAXIMUM ALLOWABLE ANGLE OF REPOSE FOR THE SIDE OF AN

EXCAVATION IN EXCESS OF 5' DEPTH

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R 408.40942 Supporting systems; angle of repose; tie backs; sheeting;

additional bracing.

Rule 942. (1) The angle of repose and the design of the supporting system for a side

of an excavation shall be based on the evaluation of all of the following factors:

(a) Depth of cut and type of soil.

(b) Possible variation in the water content of the material while the excavation is open.

(c) Anticipated changes in the material due to exposure to air, sun, water, or freezing

temperatures.

(d) Load imposed by structures, equipment, overlying material, or stored material.

(e) Vibration from traffic, equipment, or blasting.

(2) A support system shall be designed by a qualified person. The design of the

support system shall be maintained at the jobsite. Changes from the design of the

support system shall be approved by a qualified person.

(3) Tie rods and other forms of tie backs used to restrain the top of sheeting shall be

anchored a minimum of 10 feet. The measurement to the anchor point shall start at the

intersection of an angle of repose with the surface of the soil retained. The tie back and

anchor shall be capable of restraining any pressure exerted on the system.

(4) When sheeting or sheet piling is used, pressures due to existing ground water

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conditions shall be considered in the design. Sheet piling shall be driven to the

predetermined depth set forth in the required design. Changes from the design shall be

approved by the designer of the support system.

(5) Materials used for a supporting system shall be in good serviceable condition. When

timbers are used, they shall be sound and free of large or loose knots.

(6) A supporting system shall include additional bracing approved by the designer of

the support system when the sides of excavations are cut adjacent to a previous known

excavation or a known fill, particularly when the separation between the previous

excavation and the new excavation is less than the depth of the excavation.

(7) Sheeting shall be braced or anchored at the bottom and along the vertical plane to

prevent lateral movement.

(8) Protective systems for use in excavations more than 20 feet in depth must be designed

by a registered professional engineer.

R 408.40943 Additional requirements for trench support systems.

Rule 943. (1) Members of support systems shall be securely connected together to

prevent sliding, falling, kickouts, or other predictable failure.

(2) The backfilling and the removal of a support system for a trench shall progress

together from the bottom of the trench. In unstable or running soil, the jacks and braces

shall be removed from above the trench after employees have cleared the trench.

(3) The excavation of material to a level that is not more 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 if 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.

(4) The installation of a support system shall be closely coordinated with the excavation

of trenches.

(5) 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.

(6) Individual members of support systems shall not be subjected to loads exceeding

those which those members were designed to withstand.

(7) 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.

R 408.40945 Trenching boxes and shields.

Rule 945. (1) Portable trench boxes or sliding trench shields may be used for the

protection of personnel in place of a shoring system or sloping. Where such trench

boxes or shields are used, they shall be designed, constructed, and maintained in a manner

that provides protection equal to or greater than the sheeting or shoring required for the

trench.

(2) The use of benching in conjunction with a portable trench box is permitted when

the toe of the trench box is not more than 2 feet above the trench bottom, but only if the

trench box is designed to resist the forces calculated for the full depth of the trench and

if there are no indications, while the trench is open, of a possible cave-in below the bottom

of the trench box.

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(3) An employee shall not be allowed in shields when shields are being installed,

removed, or moved vertically.

(4) Shield systems shall not be subjected to loads exceeding those which the system was

designed to withstand.

(5) 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.

(6) Employees shall be protected from the hazard of cave-ins when entering or exiting

the areas protected by shields.

R 408.40951 Walkways, sidewalks, roadways.

Rule 951. (1) 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.

(2) If an employee or equipment is required or permitted to cross a trench or ditch, a

walkway, runway, ramp, or bridge shall be provided and shall have a designed

capacity of not less than 3 times the imposed load. A guardrail prescribed by the

provisions of Construction Safety and Health Standard Part 21. Guarding of Walking

and Working Areas, R 408.421 to R 408.42160 and Construction Safety Standard Part

45. Fall Protection, R 408.42101 and R 408.44501, shall be provided.

R 408.40953 Adjacent structures; protection; design; inspection of shoring, bracing, and

underpinning.

Rule 953. (1) A structure that is adjacent to an excavation or trench below the level of

the base or footing of any foundation or retaining wall shall be protected against

settlement, lateral movement, undermining, or washout.

(2) Before the excavation begins, the design of the protection used shall be set forth

by a qualified person who is knowledgeable in the subject area.

(3) The shoring, bracing, and underpinning shall be inspected daily or more often, as

conditions warrant, by a competent person.

(4) Where the stability of adjoining buildings, walls, or other structures is endangered

by excavation operations, support systems such as shoring, bracing, or underpinning shall

be provided to ensure the stability of such structures for the protection of employees.

(5) Excavation below the level of the base or footing of any foundation or retaining wall

that could be reasonably expected to pose a hazard to employees shall not be permitted

except when 1 of the following applies:

(a) A support system, such as underpinning, is provided to ensure the safety of

employees and the stability of the structure.

(b) The excavation is in stable rock.

(c) A registered professional engineer has approved the determination that the structure

is sufficiently removed from the excavation so as to be unaffected by the excavation

activity.

(d) A registered professional engineer has approved the determination that such

excavation work will not pose a hazard to employees.