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1 Chapter – 10 Subparts P through U and Related Safety Practices.

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1 1 Chapter – 10 Subparts P through U and Related Safety Practices

2 2 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

3 3 Subpart P  Excavations.  Cave-ins.  Other Hazards. It contains the Following sections:

4 4 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.

5 5 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.

6 6 Planning Requirements  Traffic in the vicinity of the excavation.  Proximity of structures or equipment to the excavation.  Soil factors.  Surface and ground water.  Weather.

7 7 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.

8 8 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.

9 9 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.

10 10 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.

11 11 Excavations dug in this configurations are called benched.

12 12 Trench shield can be used to protect workers from cave-ins.

13 13 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.

14 14 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.

15 15 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.

16 16 Other Hazards: Requirements and Related Safety Practices  Fall, Load and Equipment Hazards.  Water Accumulation Hazards.  Hazardous or Toxic Atmospheres.  Access and Egress Hazards.

17 17 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.

18 18 Warning systems should be used to alert workers when they are approaching an excavation

19 19 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.

20 20 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.

21 21 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.

22 22 What's wrong with this picture?

23 23 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.

24 24 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.

25 25 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.

26 26 Subpart Q  Subpart Q covers the requirements and related safety practices for concrete construction and masonry work.  It contains the following sections: to

27 27 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.

28 28  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.

29 29 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.

30 30 –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. Concrete Equipment and Tools

31 31 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.

32 32 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

33 33 Pre-Cast Concrete: Requirements and Related Safety Practices  Pre-cast concrete is poured in forms at a location off the construction.

34 34 Pre-Cast Concrete: Requirements and Related Safety Practices  The most common uses of pre cast concrete construction bridges, parking garages, commercial buildings and multi- story 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.

35 35 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.

36 36 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.

37 37 Subpart R  Subpart R covers the requirements and related safety practices for structural steel construction and assembly.  It contains the following sections: to

38 38 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.

39 39 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

40 40 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.

41 41 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.

42 42 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.

43 43 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.

44 44 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.

45 45 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;

46 46 Subpart S  Subpart S covers the construction of underground tunnels, shafts, chambers and passageways.  It contains the following sections: to

47 47 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.

48 48  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.

49 49  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.

50 50  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.

51 51  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.

52 52 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.

53 53 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.

54 54 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.

55 55 Subpart T  Subpart T covers the requirements and related safety practices for demolition.  It contains the following section: to

56 56 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.

57 57 Subpart U  It covers the requirements for blasting and the use of explosives on construction sites.  It contains the following to

58 58 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.

59 59 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

60 60 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.

61 61 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.

62 62 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.

63 63 References      DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138 DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138        David L. Geotsch “Construction Safety and Health”


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