Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-155 - Safety standards for construction work › Part N - EXCAVATION, TRENCHING, AND SHORING › Section 296-155-650 - Scope, application, and definitions applicable to this part

Current through Register Vol. 24-14, July 15, 2024
(1)
Scope and
				application.
This part applies to all open excavations made in the
				earth's surface. Excavations are defined to include trenches.
(2)
Definitions applicable to this
				part.
Accepted engineering requirements or practices.
Those requirements which are compatible with standards of practice required by
				  a registered professional engineer.
Aluminum hydraulic shoring.
A preengineered
				  shoring system comprised of aluminum hydraulic cylinders (crossbraces) used in
				  conjunction with vertical rails (uprights) or horizontal rails (walers). Such
				  system is designed, specifically to support the sidewalls of an excavation and
				  prevent cave-ins.
Bell-bottom pier hole.
A type of shaft or
				  footing excavation, the bottom of which is made larger than the cross section
				  above to form a belled shape.
Benching (benching system).
A method of
				  protecting employees from cave-ins by excavating the sides of an excavation to
				  form one or a series of horizontal levels or steps, usually with vertical or
				  near-vertical surfaces between levels.
Cave-in.
The separation of a mass of soil or
				  rock material from the side of an excavation, or loss of soil from under a
				  trench shield or support system, and its sudden movement into the excavation in
				  quantity that it could entrap, bury, injure, or immobilize a person.
Competent person.
One who can identify existing
				  or predictable hazards in the surroundings that are unsanitary, hazardous, or
				  dangerous to employees. Also has authorization or authority by the nature of
				  their position to take prompt corrective measures to eliminate them. The person
				  must be knowledgeable in the requirements of this part.
Cross braces.
The horizontal members of a
				  shoring system installed perpendicular to the sides of the excavation, the ends
				  of which bear against either uprights or wales.
Excavation.
Any person-made cut, cavity, trench,
				  or depression in the earth's surface, formed by earth removal.
Faces or sides.
The vertical or inclined earth
				  surfaces formed as a result of excavation work.
Failure.
The breakage, displacement, or
				  permanent deformation of a structural member or connection so as to reduce its
				  structural integrity and its supportive capabilities.
Hazardous atmosphere.
A atmosphere which by
				  reason of being explosive, flammable, poisonous, corrosive, oxidizing,
				  irritating, oxygen deficient, toxic, or otherwise harmful, may cause death,
				  illness, or injury.
Kickouts.
Accidental release or failure of a
				  cross brace.
Protective system.
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.
Ramp.
An inclined walking or working surface
				  that is used to gain access to one point to another, and is constructed from
				  earth or from structural materials such as steel or wood.
Registered professional engineer.
A person who
				  is registered as a professional engineer in the state of Washington. The
				  registered professional engineer must comply with the Washington state
				  department of licensing requirements,
				  chapter
				  18.43 RCW.
Sheeting.
The members of a shoring system that
				  retain the earth in position and in turn are supported by other members of the
				  shoring system.
Shield (shield system).
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 WAC
				  296-155-657(3)(c) or
				  (d). Shields used in trenches are usually
				  referred to as "trench boxes" or "trench shields."
Shoring (shoring system).
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.
Sides.
See "faces."
Sloping (sloping system).
A method of protecting
				  employees from cave-ins by excavating to form sides of an excavation that are
				  inclined away from the excavation so as to prevent cave-ins. The angle of
				  incline required to prevent a cave-in varies with differences in such factors
				  as the soil type, environmental conditions of exposure, and application of
				  surcharge loads.
Stable rock.
A natural solid mineral material
				  that can be excavated with vertical sides and will remain intact while exposed.
				  Unstable rock is considered to be stable when the rock material on the side or
				  sides of the excavation is secured against caving-in or movement by rock bolts
				  or by another protective system that has been designed by a registered
				  professional engineer.
Structural ramp.
A ramp built of steel or wood,
				  usually used for vehicle access. Ramps made of soil or rock are not considered
				  structural ramps.
Support system.
A structure such as
				  underpinning, bracing or shoring, which provides support to an adjacent
				  structure, underground installation, or the sides of an excavation.
Tabulated data.
Tables and charts approved by a
				  registered professional engineer and used to design and construct a protective
				  system.
Trench (trench excavation).
A narrow excavation
				  in relation to its length made below the surface of the ground. In general, the
				  depth is greater than the width, but the width of a trench (measured at the
				  bottom) is not greater than 15 feet (4.6m). If forms or other structures are
				  installed or constructed in an excavation so as to reduce the dimension
				  measured from the forms or structure to the side of the excavation to 15 feet
				  (4.6 m) or less (measured at the bottom of the excavation), the excavation is
				  also considered to be a trench.
Trench box.
See "shield."
Trench shield.
See "shield."
Uprights.
The vertical members of a trench
				  shoring system placed in contact with the earth and usually positioned so that
				  individual members do not contact each other. Uprights placed so that
				  individual members are closely spaced, in contact with or interconnected to
				  each other, are often called "sheeting."
Wales.
Horizontal members of a shoring system
				  placed parallel to the excavation face whose sides bear against the vertical
				  members of the shoring system or earth.
Statutory Authority: Chapter 49.17 RCW. 94-15-096 (Order
					 94-07), § 296-155-650, filed 7/20/94, effective 9/20/94. Statutory
					 Authority: Chapter 49.17 RCW and
					 RCW
					 49.17.040, [49.17].050 and [49.17].060.
					 92-22-067 (Order 92-06), § 296-155-650, filed 10/30/92, effective 12/8/92.
					 Statutory Authority: Chapter 49.17 RCW. 91-03-044 (Order 90-18), §
					 296-155-650, filed 1/10/91, effective 2/12/91. Statutory Authority:
					 RCW
					 49.17.040 and
					 49.17.050. 86-03-074 (Order
					 86-14), § 296-155-650, filed 1/21/86. Statutory Authority:
					 RCW
					 49.17.040,
					 49.17.050 and
					 49.17.240. 81-13-053 (Order 81-9),
					 § 296-155-650, filed 6/17/81; Order 74-26, § 296-155-650, filed
					 5/7/74, effective 6/6/74.