PROTECTION IN CONSTRUCTION, DEMOLITION AND
EXCAVATION OPERATIONS
(Statutory authority: Labor Law, §§27-a, 27, 29)
SUBPART 23-4 EXCAVATION OPERATIONS
23-4.1 General requirements
23-4.2 Trench and area type excavations
Table I
Steepest Allowable Unbraced Slopes
Table II Maximum Horizontal
Distance Between Edges of Sheeting
Table III Minimum Sizes of Stringers and Braces
23-4.3 Access to excavations
23-4.4 Sheeting, shoring and bracing.
23-4.5 Use of Tables III and IV
Table IV Minimum Sizes of Stringers and Braces
SUBPART 23-4
EXCAVATION OPERATIONS
Historical Note
Subpart (§§23-4.1 – 23-4.5) added, filed May 30, 1972 eff. June 1, 1972.
§ 23-4.1 General requirements.
(a) Stability of structures. Except in hard rock, whenever any
excavation is to be performed in the vicinity of buildings,
structures or utilities, the integrity, stability and structural
adequacy of such buildings, structures or utilities shall be
maintained at all times by the use of underpinning, sheet piling,
bracing or other equivalent means to prevent damage to or failure of
foundations, walls, supports or utility facilities and to prevent
injury to any person. Such underpinning, sheet piling, bracing or
equivalent means shall be inspected at least once each day or more
often if conditions warrant. Every such inspection shall be
conducted by an experienced, designated person.
(b) Prohibited entry. No person shall be suffered or permitted to
enter any trench or similar excavation where he may be exposed to
side or bank failure or cave-in unless proper safeguards for his
protection have been provided.
Historical Note
Sec. added, filed May 30, 1972 eff. June 1, 1972.
§ 23-4.2 Trench and area type excavations.
(a) Whenever any person is required to work in or is lawfully
frequenting any trench or excavation five feet or more in depth
which has sides or banks with slopes steeper than those permitted in
Table I of this Subpart, such sides or banks shall be provided with
sheeting and shoring in compliance with this Part (rule). Such
sheeting and shoring system shall be in contact with the sides or
banks of such trench or excavation. A designated person shall
carefully inspect such sheeting and shoring at least once each day
and more frequently in the event of rain, the presence of additional
surface or ground water from any source, excessive ground vibrations
or whenever additional loads of any kind have been imposed near or
adjacent to such excavation. Additional protection against slides
and cave-ins shall be provided whenever necessary. Any trench or
excavation in clay, sand, silt, loam or nonhomogenous soil which has
sides or banks more than three feet but less than five feet in depth
shall be provided with side or bank protection in compliance with
this Part (rule). Such side or bank protection shall not be required
where an employer maintains on file at the excavation site a dated
certification in writing by a designated person who is qualified by
training and experience indicating that such person has examined the
sides and banks and has found them to be stable and not subject to
failure or cave-in. Such certification shall be available for
examination by the commissioner.
(b) Where the sides or banks of a trench or area type excavation may
be sloped back without causing subsidence or damage to buildings,
structures, utilities, roads, streets, highways or similar
facilities, sloping of the excavation sides or banks may be used as
protection in lieu of the sheeting and shoring required by this Part
(rule), provided such sloping conforms to the values set forth in
Table I of this Subpart. Such sloping of the excavation sides or
banks may be used in combination with sheeting and shoring. When
such a combination is used, a level bench at least 24 inches in
width shall be left between the toe of the sloped section and the
braced section. The sheeting of the braced section shall extend at
least 12 inches above the elevation of such level bench.
(c) Any unbraced sloped excavation which extends below the ground
water table, especially adjacent to rivers, reservoirs or other
bodies or sources of free water, shall be under the direct
supervision of an experienced person designated by the employer.
(d) In any excavation with a combination of sloped unbraced sides or
banks near the surface and vertical sheeted and shored sides or
banks near the bottom, the steepest allowable slope of such unbraced
portion of the sides or banks shall be based on the total excavation
depth. (See Table I of this Subpart.)
(e) Where any side or bank of an excavation is undercut and has a
reverse slope toward the trench centerline creating a vertical load
on the sheeting and shoring, such sheeting and shoring shall be
designed by, and installed in accordance with the specifications
determined by, a professional engineer licensed to practice in the
State of New York. Such sheeting and shoring shall be designed to
support the vertical load imposed by the overhanging material as
well as the load imposed by the adjacent ground.
(f) Excavated material and other superimposed loads shall be placed
at least 24 inches back from the edges of any open excavation and
shall be so placed or piled that no part thereof can slide, fall or
roll into the excavation. Such 24-inch required clearance may be
reduced if the employer installs a barrier or similar retaining
device which is designed and constructed to prevent excavated
material from falling into the excavation.
TABLE I
STEEPEST ALLOWABLE UNBRACED SLOPES
| Type of Soil or Rock | Depth of Excavation | 5 to 10 ft. | Over 10 ft. |
|
Still cohesive soil |
1 ½ vertical on 1 horizontal |
1 vertical on 1 horizontal (trench) 1 ½ vertical on 1 horizontal (area) |
|
Noncohesive soil |
1 vertical on 1 horizontal 1 vertical on 1 ½ horizontal (when subject to vibrations |
1 vertical on 1 horizontal 1 vertical on 1 ½ horizontal (when subject to vibrations) |
|
Soft cohesive or wet flowing soil |
1 vertical on 1 horizontal 1 vertical on 1 ½ horizontal (when subject to vibrations) |
1 vertical on 1 ½ horizontal (trench) 1 vertical on 1 horizontal (area) 1 vertical on 1 ½ horizontal (when subject to vibrations) |
|
Stable rock |
Vertical sides permitted |
Vertical sides permitted |
|
Unstable rock |
1 ½ vertical on 1 horizontal |
1 ½ vertical on 1 horizontal |
| Return | Notes: The slopes given in Table I are the steepest allowable. Conditions may occur requiring the use of flatter slopes to prevent slope failure and subsidence of adjacent areas. A slope shall start from the bottom of each side of an excavation or where the lower portions of such sides consist of stable rock from the top of such rock. |
(g) All sides or banks, slopes and areas in and adjacent to any
excavation shall be stripped and cleared of loose rock or any other
material which may slide, fall, roll or be pushed upon any person
located in such excavation.
(h) Any open excavation adjacent to a sidewalk, street, highway or
other area lawfully frequented by any person shall be effectively
guarded. Such guarding shall consist of a substantial fence or
barricade. As an alternative, such guarding may consist of an
extension of the sheeting above the ground surface adjacent to the
excavation to a height of at least 42 inches above such adjacent
street, highway or other area lawfully frequented by any person. In
lieu of such guarding, protection may be afforded by a substantial
covering installed over such excavation. Such covering shall consist
of planking at least two inches thick full size, properly supported
exterior grade plywood at least three-quarters inch thick or
material of equivalent strength. Where it is possible that the
movement of vehicles or other heavy equipment will take place over
such covering, the covering shall be of sufficient strength to
withstand such loading without structural failure of the covering or
of the support system.
(i) Where no work is being performed in an unattended open
excavation which has substantially vertical sides or banks three
feet or more in depth, such excavation shall be effectively guarded
on all open sides regardless of the location of such excavation.
Such guarding shall consist of a fence, a barricade or a safety
railing constructed and installed in compliance with this Part
(rule). As an alternative, such guarding may consist of an extension
of the sheeting above the excavation to a height of at least 42
inches above the adjacent ground, grade or equivalent level. In lieu
of such guarding, protection may be afforded by a substantial
covering installed over the excavation. Such covering shall consist
of planking at least two inches thick full size, properly supported
exterior grade plywood at least three-quarters inch thick or
material of equivalent strength. Where it is possible that the
movement of vehicles or other heavy equipment will take place over
such covering, the covering shall be of sufficient strength to
withstand such loading without structural failure of the covering or
of the support system.
(j) Temporary sheet piling installed in an excavation to permit the
construction of a retaining or structural wall shall be left in
place until such wall has developed adequate strength to support any
load intended to be imposed upon such wall.
(k) Persons shall not be suffered or permitted to work in any area
where they may be struck or endangered by any excavation equipment
or by any material being dislodged by or falling from such
equipment.
(l) The sides of any excavation in stable rock may be vertical and
are not required to be provided with sheeting and shoring. Such
sides shall be scaled and kept free of all loose rock or material
that may be dislodged or may fall into such excavation.
Historical Note
Sec. added, filed May 30, 1972 eff. June 1, 1972.
§ 23-4.3 Access to excavations.
Ladders, stairways or ramps constructed in compliance with this Part
(rule) shall be provided in every excavation more than three feet in
depth for safe access and egress. Such ladders, stairways or ramps
shall be installed in sufficient number and in such locations as to
be readily accessible to any person wishing to enter or leave such
excavation without more than 25 feet of lateral travel.
Historical Note
Sec. added, filed May 30, 1972 eff. June 1, 1972.
§ 23-4.4 Sheeting, shoring and bracing.
(a) Where any excavation is not protected by sloped sides or banks
in compliance with Table I of this Subpart, any person in such
excavation shall be protected by sheeting, shoring and bracing in
compliance with Tables II, III and IV of this Subpart. Sizes of
materials listed in the tables are nominal or trade dimensions.
TABLE II
MAXIMUM HORIZONTAL DISTANCE BETWEEN EDGES OF SHEETING
Type of Soil |
Excavation Depth |
||
Stiff cohesive soil |
Tight |
Tight |
Tight |
Noncohesive soil |
2 feet |
Tight |
Tight |
Soft cohesive or wet flowing soil |
Tight |
Tight |
Tight |
| Return |
(b) Shores, struts and braces, whether horizontal or inclined,
shall be of adequate size to provide stiffness and adequately braced
to withstand the loads intended to be imposed thereon. The ends of
all braces shall be individually anchored and fastened to fully
resist all imposed forces and to prevent such braces from shifting
or slipping. The placing of any inclined shores, struts or braces at
any angle exceeding 30 degrees from the horizontal is prohibited.
(c) Each earth-supported shore, strut or brace shall bear against a
footing of sufficient area and stability to prevent any subsidence,
yield or shifting of such shore, strut or brace.
TABLE III
MINIMUM SIZES OF STRINGERS AND BRACES
Narrow Trenches – Horizontal Cross-Braces Not Longer Than Four
Feet
| Trench Depth | Type of Soil | Vertical Spacing of Stringers |
| 5 to 10 ft. | Stiff cohesive | 4 ft. max. |
| Non cohesive | 4 ft. max. | |
| Soft cohesive & wet flowing | 4 ft. max. | |
| Over 10 to 20 feet | Stiff cohesive | 4 ft. max. |
| Non cohesive | 4 ft. max. | |
| Soft cohesive & wet flowing | 4 ft. max. |
| Horizontal Spacing of Cross-Braces | 4 Feet | 6 Feet | 8 Feet | 12 Feet | Stringers | Braces | Stringers | Braces | Stringers | Braces | Stringers | Braces |
| 4x4 | 6x6 or 4x8 | 4x4 | 4x4 | 6x6 | 4x4 | 8x8 | 4x6 |
| 4x4 | 6x6 | 4x4 | 4x4 | 6x8 | 4x4 | 8x10 | 6x6 |
| 4x4 | 6x10 | 4x4 | 4x6 | 8x10 | 6x6 | 10X12 | 6x8 |
| 4x4 | 6x6 | 4x4 | 4x4 | 8x8 or 6x10 | 4x6 | 10X10 | 6x6 |
| 6x6 | 8x10 | 6x8 | 6x8 | 10X12 | 8x8 | * | * |
| Over 20 ft. | For any trench over 20 feet in depth the sheeting, shoring and bracing systems shall be designed by a professional engineer licensed to practice in the State of New York. A copy of the plans and specifications for any such bracing system shall be kept at the job site available for examination by the commissioner. | ||||||
| *Sizes of timber for such conditions become
excessive. A special structure designed by a professional
engineer licensed to practice in the State of New York shall
be constructed and used for the specific condition involved. |
||||
| Return | Note: Timber sizes are nominal or trade dimensions. |
(d) Each end of each stringer shall be individually braced. Where
stringers are terminated to form individual panel type sheeting,
each such panel shall be braced at either end.
(e) In lieu of sheeting and shoring and where conditions permit, a
self-supporting movable shield of timber or metal may be used and
moved ahead as the excavation and construction progresses. The
supporting capacity of such a shield shall be equal in all respects
to the sheeting and shoring set forth in Tables II, III and IV of
this Subpart. When any person is located in such excavation at any
point not protected by such shield, sheeting and shoring as set
forth in Tables II, III and IV of this Subpart shall be provided.
(f) In lieu of wood, screw jacks of adequate size and stability may
be used as cross bracing in the sheeting and shoring of any
excavation. Any type of cross bracing used shall be in a true
horizontal position, shall be securely fastened and shall be
prevented from shifting or slipping by adequately fastened scabs or
blocks.
(g) When the depth of an excavation requires the use of two vertical
lengths of sheeting, one above the other, the lower sheeting shall
be set inside the bottom stringers of the upper sheeting and shall
be driven down and braced as the excavation continues.
(h) Excavations which are generally parallel to existing underground
pipe lines, utilities or structures of any kind shall be tightly
sheeted and shored alongside such pipe lines, utilities or
structures where they are exposed by such excavations.
(i) Timber sheeting shall consist of structurally sound hardwood at
least two inches by six inches in size or of lumber of equivalent
strength. The actual thickness of such timber sheeting shall be
consistent with the size of the supporting timbers and the depth of
the excavation.
Historical Note
Sec. added, filed May 30, 1972 eff. June 1, 1972.
§ 23-4.5 Use of Tables III and IV.
The use of Tables III and IV shall be subject to the following
requirements:
(a) The sizes of members shown in Tables III and IV are the minimum
requirements for timber bracing systems used in the sheeting and
shoring of excavations.
(b) Steel, aluminum or combinations of steel, aluminum and timber
bracing systems of equivalent strength and capacity may be used in
place of timber bracing systems.
(c) Portable, adjustable-type metal shores for trench bracing
systems shall be approved.
(d) Braces shall be so placed that the full cross-sectional areas
required by Tables III and IV of this Subpart bear against the
stringers.
(e) Stringers shall be placed with their least dimensions flat
against the sheeting.
(f) Where any side of an excavation is a combination of an unbraced
slope in accordance with Table I of this Subpart near the surface
and a braced vertical section near the bottom, the sizes of the
bracing members shall be determined from Tables III and IV of this
Subpart. In such case, the excavation depth shall be the sum of the
depth of the braced section plus one-half the depth of the unbraced
sloped section.
(g) The uppermost brace of any bracing system shall be located not
more than two feet below the top of the supported material.
(h) The maximum distance between the lowest brace and the bottom of
the excavation shall not exceed three feet, except where the
sheeting or soldier beam is embedded as stipulated in subdivision (i)
below.
TABLE IV
MINIMUM SIZES OF STRINGERS AND BRACES
Wide Trenches—Horizontal Cross-Braces More Than Four Feet But Not
Longer Than Eight Feet
| Trench Depth | Type of Soil | Vertical Spacing of Stringers |
| 5 to 10 ft. | Stiff cohesive | 4 ft. max. |
| Non cohesive | Over 4 ft. to 6 ft. max . | |
| Soft cohesive & wet flowing | 4 ft. max. | |
| Over 10 to 20 feet | Stiff cohesive | 4 ft. max. |
| Non cohesive | 4 ft. max. | |
| Soft cohesive & wet flowing | 4 ft. max. |
| Horizontal Spacing of Cross-Braces | 4 Feet | 6 Feet | 8 Feet | 12 Feet | Stringers | Braces | Stringers | Braces | Stringers | Braces | Stringers | Braces |
| 4x4 | 4x4 | 6x6 or 4x8 | 4x6 | 6x6 | 4x6 | 8x8 | 6x6 |
| 6x6 or 4x8 | 4x6 | 6x6 | 6x6 | 6x8 | 6x8 | 8x10 | 6x8 |
| 6x6 | 6x6 | 6x10 | 6x6 | 8x10 | 6x6 | 10X12 | 8x8 |
| 4x6 | 4x6 | 6x6 | 6x6 | 8x8 or 6x10 | 10x10 | 8X8 | 6x10 |
| 6x8 | 6x8 | 8x10 | 6x10 | 10X12 | 8x10 | * | * |
| Over 20 ft. | For any trench over 20 feet in depth the sheeting, shoring and bracing systems shall be designed by a professional engineer licensed to practice in the State of New York. Such design plan, including design analysis and specifications, shall be submitted to the board for special approval before any work is performed on such excavation. | ||||||
| *Sizes of timber for such conditions become
excessive. A special structure designed by a professional
engineer licensed topractice in the State of New York shall be constructed and used for the specific condition involved. |
||||
| Return | Note: Timber sizes are nominal or trade dimensions. |
(i) If the bottom of the sheeting or soldier beam is embedded
below the bottom of the excavation, the maximum distance between the
lowest brace and the bottom of the excavation shall not exceed the
vertical spacing for braces allowed in Tables III and IV of this
Subpart. The minimum depth of embedment of the sheeting or soldier
beam shall be three feet. The actual depth of each such embedment
shall be such that there is no significant movement of the bottom of
the sheeting or soldier beam. Exception: Where the operation being
performed, such as laying large diameter concrete pipe or rein-
forced concrete culverts, precludes the placing of vertical bracing
as specified in subdi- visions (h) and (i) above, the vertical
spacing may be in accordance with a specific design and plans made
by a professional engineer licensed to practice in the State of New
York. Such specified bracing system shall be designed so that the
sheeting and shoring will with- stand all the forces intended to be
imposed thereon. Copies of the design and plans of such sheeting and
shoring system shall be kept at the job site available for
examination by the commissioner.
(j) The bracing or shoring of trenches shall be continued as the
excavation progresses in length. No person except workmen
fabricating the required sheeting and shoring system shall be
allowed inside such excavation until the required sheeting and
shoring system has been completed.
(k) Backfilling and removal of trench supports shall progress
together from the bottom of the trench. Jacks or braces shall be
released slowly and, in unstable soil, ropes shall be used to remove
the jacks or braces from above after employees have vacated the
trench.
Historical Note
Subpart added, filed May 30, 1972 eff. June 1, 1972.
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