Chapter – 10
Subparts P through U and Related
Safety Practices
1
Major Topics
 Subpart P: Excavations
 Subpart Q: Concrete and Masonry Construction
 Subpart R: Steel Erection
 Subpart S: Tunnels, Shafts, Caissons, Cofferdams
and Compressed Air
 Subpart T: Demolition
 Subpart U: Blasting and Use of Explosives
2
Subpart P
 Excavations.
 Cave-ins.
 Other Hazards.
It contains the
Following sections:
1926.650
1926.651
1926.652
3
Excavations and Related Safety Practices
 Every year in the United States, about 200
construction workers engaged in trench
work die. The most common hazards of
excavation accidents include cave-ins,
contact with energized power sources or
conductors, toxic atmospheres, loose rocks,
rising water and the collapse of nearby
structures or equipment.
4
Excavations: General Requirements and
Related Safety Practices
 An “excavation” is a man-made cut, cavity or
trench in the ground made by removing earth.
 The most common form of excavation in
construction is the trench, which is a narrow
excavation that is deeper than it is wide and is no
wider than 15 feet.
 Subpart P applies to open excavations except
surface mines and certain house foundation
excavations.
5
Planning Requirements
 Traffic in the vicinity of the excavation.
 Proximity of structures or equipment to the excavation.
 Soil factors.
 Surface and ground water.
 Weather.
6
On-Site Inspections
 OSHA requires daily inspection by a competent person to
detect possible problems or hazards in excavations and in
the vicinity of excavations.
 Inspections must also be made following heavy rains or
any man-made activities that might de-stabilize the
excavation.
7
Cave-Ins: General Requirements and
Related Safety Practices
 A cave-in is a collapse of a geologic formation,
mine or structure.
 Excavation cave-ins are a major source of
fatalities within the construction industry each
year.
8
Support Systems
 OSHA requires that workers in excavations be protected
by one of the following methods:
• Sloping and benching the sides of the excavation;
• Supporting the sides of the excavation;
• Placing a shield between the side of the excavation and
the work area in the excavation.
9
Sloping of the sides of an excavation no less than 1.5 (horizontal)
:1 (Vertical) helps to ensure worker safety in excavation up to
20feet deep.
10
Excavations dug in this configurations are called benched.
11
Trench shield can be used to
protect workers from cave-ins.
12
Specific Safety Precautions
 Construction companies that undertake excavation work
are required to provide support systems, such as shoring,
bracing, or underpinning, to adequately stabilize structures
in the vicinity of an excavation.
 These structures include walls, buildings, towers,
sidewalks and pavements.
13
Installation and Removal of
Protective Systems
 Installing protective systems can be just as dangerous as
working in an excavation. Consequently, OSHA requires the
following safe practices when installing protective systems:
– Make sure that all structural members of the support system
are properly and securely connected.
– Make sure that no structural component of a support system
is overloaded.
– When temporary removal of a structural component of a
support system is necessary, first install another to take its
place.
– Coordinate the installation of support systems closely with
excavation work.
14
Materials and Equipment
 OSHA has established the following safe practices and
requirements:
– Companies must use the materials and equipment that are
free of defects.
– Manufactured materials and equipment must be used in
strict accordance with the manufacturer specifications.
– Immediately remove from service any material or
equipment that is deemed to be unsafe by a competent
person.
– Materials or equipment removed form service cannot be
returned to service without inspection by a registered
professional engineer.
15
Other Hazards: Requirements and
Related Safety Practices
 Fall, Load and Equipment Hazards.
 Water Accumulation Hazards.
 Hazardous or Toxic Atmospheres.
 Access and Egress Hazards.
16
Fall, Load and Equipment Hazards
 OSHA’s requirements and safe practices with regards to falls,
loads and equipment are as follows:
– Construct retaining devices around excavations or keep all
equipment and loads back form the edge at least 2 feet.
– Provide protective barricades or other equivalent means to guard
against falling rock, soil or other materials.
– Do not allow people to work on sloped or benched excavation
walls at levels above other workers in the excavation.
– Provide warning systems that alert workers and operators
of equipment that they are coming too near the edge of the
excavation.
17
Warning systems should be used to alert workers when they are
approaching an excavation
18
Water Accumulation Hazards
 Workers should not be allowed to perform their duties in
an excavation in which water is accumulating, unless the
appropriate precautions have been taken to remove the
water.
 These precautions are as follows:
– Properly functioning water-removal equipment.
– Excavations that are subject to runoff.
19
Hazardous or Toxic Atmospheres
 Before allowing a worker to enter an excavation that is 4 feet
or more deep or that could reasonably be expected to have a
hazardous atmosphere, a competent person must test the
atmosphere.
 If a hazardous condition is determined to exist, workers must
use the appropriate respiratory protection devices and
ventilation of the excavation must be undertaken.
 Emergency rescue equipment must be made readily available
if a hazardous atmosphere might exist or develop in the
excavation.
 There must be an observer present at all times when the
worker is in the confined space.
20
Access and Egress Hazards
 For trenches 4 feet or more deep, OSHA
regulations and safe practice require that workers
be provided with appropriate means of access and
egress, such as ladders, steps, ramps or other
equivalent means.
 If ramps are used, they must be designed or
approved by competent person.
21
What's wrong with this
picture?
22
What's wrong with this
picture?
He is working alone at the bottom of
almost a 22 ft. deep vertical trench.
Excavated soil has been stockpiled at the
very edge of the trench, adding to the
pressure on the trench walls.
Neither a ramp nor ladder has been
provided for the worker to escape.
Finally there is nothing to protect him
from a cave-in; no sloping back of the
trench walls, no shoring of the walls, and
no shielding of the worker.
23
CASE STUDY:
 "OSHA Proposes $210,000 in Penalties
Following Trenching Fatality"
 OSHA Regional News (Birmingham, AL )
 February 22, 2006
 OSHA has issued citations against a utility contractor and
proposed penalties totaling $210,000, following the
investigation of a fatal accident at a Clay, Ala.,
construction site. OSHA began an inspection at the Steeple
Chase subdivision after being notified that a worker was
trapped in a collapsed trench. Rescue attempts failed.
24
Agency investigators determined that employees had been working
in an 18-foot-deep trench with excavated soil piled 10 feet high at
the edge of the trench walls. The company received four willful
citations, with proposed penalties of $196,000, for allowing
workers to ride on an excavator bucket and then jump into trenches;
failing to provide employees with adequate means to enter and exit
trenches; placing excavated materials within two feet of trench
walls; inadequately shoring and sloping trench walls, and failing to
conduct daily inspections and remove employees from the site
when hazardous conditions were observed.
OSHA also issued four serious citations, with proposed
penalties of $14,000, for allowing employees to work under
suspended loads of sewer pipes and for failing to train employees
and provide them with hard hats, drinking water and bathroom
facilities.
25
Subpart Q
 Subpart Q covers the requirements and
related safety practices for concrete
construction and masonry work.
 It contains the following sections:
• 1926.700 to 1926.706
26
General Requirements and Related
Safety Practices for Concrete Work
 OSHA specifies requirements and safe practices that apply to
all types of concrete work. The general requirements are:
– Before any type of load can be placed on a concrete structure or
any concrete portion of a structure an individual qualified in the
field of structural design must determine that the structure or the
portion of a structure being used can support the load.
– Workers involved in tying or placing reinforcing steel at heights
of 6 feet or more above any working surface must wear the
appropriate fall protection devices.
– When reinforcing strands are tensioned at the job site, workers
should not be allowed behind the jack during the tensioning
process.
27
 Concrete buckets must be equipped with safety latches to
prevent accidental or premature dumping. Workers should not
be allowed to work underneath concrete buckets when they are
being lifted or elevated.
• Protruding reinforcing bars must be guarded to prevent
impalement if a worker falls on one.
28
Concrete Equipment and Tools
 General requirements for the concrete equipment and tools
are summarized as:
– Equipment such as saws, mixers, screens and pumps
must be properly locked out and tagged out before
workers are allowed to perform routine maintenance
duties on them.
– Concrete mixers with loading skip of 1 cubic yard or
larger must be equipped with a mechanical means of
clearing the skip of material.
– Electrically powered, rotating trowel machines must be
equipped with an automatic shutoff switch that
activates if the operator releases the handles.
29
Concrete Equipment and Tools
– Concrete pumping systems that use pipes for
discharging the concrete must be equipped with pipe
supports that are rated for at least 100 percent overload.
– Workers who use a pneumatic hose to apply cement,
sand or water mixture must wear appropriate head and
face protection.
– Masonry saws must be equipped with a guard over the
blade and a method for retaining blade fragments.
30
Cast-In-Place Concrete: Requirements
and Related Safety Practices
 The term “cast-in-place” means
that the concrete is poured (cast) at
the job site (in place) into forms
that are constructed or assembled
at the site.
 It involves the following activities:
1. Building or assembling forms
2. Placing rebar into the forms.
3. Pouring concrete
4. Treating the surface of the
concrete.
31
Requirements and safety practices for
cast-in-place concrete
 Forms must be designed and built to withstand all vertical
and lateral loads that might be applied to them.
 Shoring equipment must be inspected before erection to
ensure that it meets the specifications set forth in the
engineering drawings.
 Reinforcing bars for vertical components of the structure
must be properly supported to prevent overturning or
collapse.
 Forms and shores must remain in place until it has been
determined by a standard test approved by the ASTM that
the concrete has cured sufficiently to support its own
weight and that of any superimposed loads
32
Pre-Cast Concrete: Requirements and
Related Safety Practices
 Pre-cast concrete is poured in forms at a location off the
construction.
33
Pre-Cast Concrete: Requirements and
Related Safety Practices
 The most common uses of pre cast concrete construction
bridges, parking garages, commercial buildings and multistory residential building
 Pre-cast concrete components must be properly supported
until they are permanently attached to prevent overturning
or collapse.
 Lifting mechanisms must be capable of supporting at least
five times the anticipated load.
 Workers should not be allowed to work under pre-cast
components that are in the process of being erected.
34
Lift-Slab Concrete: Requirements and
Related Safety Practices
 Lift-slab concrete operations involve fabricating pre-cast
concrete components with lifting hardware embedded in
them.
 Jacks and other equipment used to lift the slabs must be
clearly marked to show the manufacturer’s specifications
for lift capacity.
 Jacking and lifting equipment must be able to support at
least 2 ½ times the anticipated load and must not be used
beyond their rated capacity.
 The maximum number of lifting units in a slab is 14, but
the preferred number is the minimum necessary to allow
the operator to keep the slab level to within prescribed
tolerances.
35
Masonry Construction: Requirements
and Related Safety Practices
 Masonry involves the use of bricks or blocks
as the primary building material.
 Stability is an issue with masonry
construction. Consequently masonry walls
more than 8 feet in height must be supported
to prevent collapse.
 Bracing used to support a masonry wall under
construction must remain in place until
permanent supporting elements of the
structure are in place. In addition to bracing, a
limited access zone must be established
wherever a masonry wall is being constructed.
36
Subpart R
 Subpart R covers the requirements and
related safety practices for structural steel
construction and assembly.
 It contains the following sections:
• 1926.750 to 1926.761
37
Structural Steel Construction
 Steel construction is a specialized field within the broader
field of construction. It has its own unique hazards, which
result in an average of 35 deaths and 2300 lost – time
injuries every year.
 The hazards most commonly associated with steel erection
work include working under loads; hoisting, landing, and
placing decking and steel joists; column stability; double
connections; and falling to lower levels.
38
Site Layout, Site- Specific Erection Plan,
and Construction Sequence: Requirements
and Related Safety Practices
 Steel erection cannot begin until the concrete used in
footings has either: a) cured to at least 75% of its intended
minimum compressive design strength; or b) has cured
sufficiently to support the loads that will be imposed
during erection.
 There must also be sufficient room for operation.
 There must be adequate roads into and through the
construction site
39
Hoisting and Rigging: Requirements and
Related Safety Practices
 Cranes used in steel erection must undergo a thorough
visual inspection before each shift to ensure that all
controls and mechanisms are in proper and safe working
order.
 The capacity of must have a safety factor of at least 5:1.
40
Column Anchorage: Requirements and
Related Safety Practices
 OSHA’s Steel
Erection Standard
required that all
columns be
anchored by a
minimum of four
anchor bolts.
41
Beams and Columns: Requirements and
Related Safety Practices
 When beams are being secured to columns, they must not
be released from the hoisting lines until secured by at least
two bolts per connection.
 One of the more hazardous tasks for steel erection workers
is making double connections.
42
Falling Object: Requirements and
Related Safety Practices
 Objects falling from a higher
level and injuring employees
working at a lower level is a
concern in steel erection.
 Consequently, the Steel
Erection Standard requires
that all materials, equipment,
and tools used by workers
who are aloft be properly
secured against falling.
43
Fall Protection: Requirements and Related
Safety Practices
 Falls from higher to lower levels represent the greatest
hazard in steel erection.
 Consequently, OSHA requires fall protection for
employees working at heights greater than 15 feet.
44
Training: Requirements and Related
Safety Practices
 OSHA requires that personnel who work in steel erection
have the necessary training.
– This training must include
• reorganization of fall hazards;
• use and proper operation of fall protection system;
• correct procedures for erecting, maintaining,
disassembling, and inspecting fall protection
systems;
• procedures for preventing falls through holes and
other openings;
45
Subpart S
 Subpart S covers the construction of underground
tunnels, shafts, chambers and passageways.
 It contains the following sections:
• 1926.800 to 1926.804
46
Underground Construction:
Requirements and Related Safety
Practices
 Underground construction has its own set of unique hazard.
 The principal hazards are:
•
•
•
•
•
•
•
•
•
•
•
safety instruction,
access and egress,
check-in and check-out procedures,
hazardous classifications,
gassy operations,
air monitoring,
ventilation,
illumination,
fire control,
hot work, and
emergencies.
47
 Safety Instruction
– Workers who will be involved in underground construction operations
must first receive the proper training.
– Training must focus on
• Air monitoring
• Ventilation
• Communication
• Flood control
• Equipment: mechanical and personal protective
• Explosives: fire prevention, and fire protection
• Emergency procedures: check-in, check-out, and evacuation plans.
• Access and Egress
– Employers are required to provide safe access and egress to underground
construction sites.
– Unauthorized entry must be both prohibited and prevented.
48
 Check –In and Check – Out Procedures
Employers must use an appropriate check-in and check-out
procedure to keep track of employees who work underground.
 Gassy Operations
In underground construction work there are potentially gassy
operations and confirmed gassy operations. Safety precautions
for gassy operations include the following as a minimum:
– Ventilation.
– Prohibiting the use of diesel
equipment
– Prohibiting smoking or other forms
of ignition in or near the work area.
– Maintaining a fire watch if any
hot work is to be performed.
49
 Air Monitoring
– A competent person must be assigned to conduct air-monitoring
courses to ensure that the ventilation available is sufficient and to
record measurements of potentially hazardous gasses.
 Ventilation
– Contractors are required to provide an adequate supply of fresh air to
all underground sites.
 Illumination
– Contractors are required to provide proper illumination in all
underground sites. When explosives are to be handled underground,
a distance of 50 feet must be maintained between any heading and
the lighting.
50
 Fire Prevention and Control
– Open flames and fires are prohibited in underground
construction sites. Smoking should be discouraged in
underground sites.
 Hot Work
– When performing hot work in underground, noncombustible
barriers must be installed in or over a shaft.
 Emergencies
– Rescue teams or services must be provided at construction sites
in which 25 or more employees work underground. A designated
person must be available to call for emergency assistance and to
maintain an accurate head count of those working underground.
51
Caissons: Requirements and Related
Safety Practices
 A Caisson is an airtight and
watertight structure in which
construction work can be done
underground or underwater.
 If a caisson is to be suspended
at any time when work is being
done in it and the bottom of the
excavation is 9 feet or more, a
shield must be erected to protect
employees.
52
Cofferdams: Requirements and Related
Safety Practices
 A Cofferdam is a watertight
enclosure that can be pumped dry
so that construction activities can
take place.
 A means must provide to prevent
flooding if overtopping of the
cofferdam by high waters is
possible.
 At least two means of rapid exit
must be provided with
cofferdams.
53
Compressed Air: Requirements and
Related Safety Practices
 Any time work is being
done under compressed
air, there must be at least
one competent person
readily available who is
familiar with all aspects
of working in these
conditions.
 Fig: Tunneling in
Compressed air without
a shield.
54
Subpart T
 Subpart T covers the requirements and related safety practices
for demolition.
 It contains the following section:
• 1926.850 to 1926.860
55
Preparatory Operations
 A critical first step before undertaking a demolition operation
is to obtain a comprehensive engineering survey of the
structure that is to be demolished. This survey helps to guard
against premature or unplanned collapse of the structure in
question.
 Once the engineering survey has been completed, all utilities
(gas, electricity and other energy sources) are disconnected
and turned off.
 Openings in floors and walls are covered or sealed.
 If combustible materials are present in the structure,
firefighting equipment must be available in nearby to the site.
56
Subpart U
 It covers the requirements for blasting and the use of
explosives on construction sites.
 It contains the following
• 1926.900 to 1926.914
57
Blasting: General Provisions and Related
Safety Practices
 All types of heat and spark producing devices are
prohibited near explosives.
 Explosives that are not being used must be stored in a
locked magazine.
 All explosives must be counted for at all times.
 Blasting operations conducted above ground should be
completed during daylight hours.
58
Blasting: General Provisions and
Related Safety Practices
 No person is allowed to handle explosives while under the
influence of drugs.
 Warning signs should be prominently displayed to warn against
the use of radio transmitters within 1000 feet of the blasting
site
59
Other Requirements in Blasting
Operations
 Before beginning the
preparations for blasting,
contractors should post
warning signs that explain the
code of blasting signals
around the blasting area.
Initiating devices may not be
stored in the same area with
other explosives.
60
Other Requirements in Blasting
Operations
 Initiating devices may not be stored in the same area with
other explosives.
 There is to be no smoking within 50 feet of explosives and
detonators.
61
Other Requirements in Blasting
Operations
 Avoid the use of electric blasting caps in any area where
extraneous electrical charges might be present that could
cause an unplanned detonation.
 Before initiating detonation, the blaster in charge makes
sure that all extra explosives, detonators, and other
extraneous materials have been removed from the blast
area and properly stored.
 No attempt can be made to remove an unexploded charge.
It must be re-primed and re-detonated, or washed out with
water.
62
References
 http://www.osha.gov/SLTC/etools/construction/images/rebar_1.jpg
 http://mattgray.org/trips/2004/weminuche/photos/ore_bucket_sky.jpg
 http://www.buildstore.co.uk/materials/images/masonryconstructionheader.jpg
 http://www.cdc.gov/eLCOSH/docs/d0500/d000533/3.jpg
 http://cache.viewimages.com/xc/3333144.jpg?v=1&c=ViewImages&k=2&d=4

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DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138
http://www.geoconsol.com/photos/DFW%20Tunnel%20&%20Pipe.jpg
http://kshitija.files.wordpress.com/2006/07/entry_fig3.gif
http://www.funnyphotos.net.au/images/building-demolition1.jpg
http://mining.mosaicprojects.net/images/millward_blasting.gif
http://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htm
http://www.jobsitesupply.com/img/cast-in-place_detail.jpg
David L. Geotsch “Construction Safety and Health”
63