cave ins and subpart q

7/31/2019 Cave Ins and Subpart Q

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Chapter 10

Subparts P through U and Related

Safety Practices


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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


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Subpart P

Excavations.

Cave-ins.

Other Hazards.It contains the

Following sections:

1926.6501926.651

1926.652


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Excavations and Related Safety Practices

Every year in the United States, about 200construction workers engaged in trenchwork die. The most common hazards of

excavation accidents include cave-ins,contact with energized power sources orconductors, toxic atmospheres, loose

rocks, rising water and the collapse ofnearby structures or equipment.


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Excavations: General Requirements andRelated Safety Practices

An excavation is a man-made cut, cavity ortrench in the ground made by removing earth.

The most common form of excavation in

construction is the trench, which is a narrowexcavation that is deeper than it is wide and isno wider than 15 feet.

Subpart P applies to open excavations exceptsurface mines and certain house foundationexcavations.


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Planning Requirements

Traffic in the vicinity of the excavation.

Proximity of structures or equipment to the excavation.

Soil factors.

Surface and ground water. Weather.


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On-Site Inspections

OSHA requires daily inspection by a competent personto detect possible problems or hazards in excavationsand in the vicinity of excavations.

Inspections must also be made following heavy rains orany man-made activities that might de-stabilize theexcavation.


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Cave-Ins: General Requirements andRelated 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 eachyear.


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Support Systems

OSHA requires that workers in excavations be protectedby 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 excavationand the work area in the excavation.


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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.


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Excavations dug in this configurations are called benched.


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Trench shield can be used toprotect workers from cave-ins.


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Specific Safety Precautions

Construction companies that undertake excavation workare required to provide support systems, such asshoring, bracing, or underpinning, to adequately stabilizestructures in the vicinity of an excavation.

These structures include walls, buildings, towers,sidewalks and pavements.


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Installation and Removal ofProtective Systems

Installing protective systems can be just as dangerousas working in an excavation. Consequently, OSHArequires the following safe practices when installingprotective systems:

Make sure that all structural members of the supportsystem are properly and securely connected.

Make sure that no structural component of a supportsystem is overloaded.

When temporary removal of a structural component ofa support system is necessary, first install another totake its place.

Coordinate the installation of support systems closely

with excavation work.


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Materials and Equipment OSHA has established the following safe practices and

requirements:

Companies must use the materials and equipmentthat are free of defects.

Manufactured materials and equipment must be usedin strict accordance with the manufacturerspecifications.

Immediately remove from service any material orequipment that is deemed to be unsafe by acompetent person.

Materials or equipment removed form service cannotbe returned to service without inspection by aregistered professional engineer.


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Other Hazards: Requirements andRelated Safety Practices

Fall, Load and Equipment Hazards.

Water Accumulation Hazards.

Hazardous or Toxic Atmospheres.

Access and Egress Hazards.


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Fall, Load and Equipment Hazards OSHAs requirements and safe practices with regards to

falls, loads and equipment are as follows:

Construct retaining devices around excavations or keep allequipment 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 benchedexcavation walls at levels above other workers in theexcavation.

Provide warning systems that alert workers andoperators of equipment that they are coming too nearthe edge of the excavation.


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Warning systems should be used to alert workers when they are

approaching an excavation


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Water Accumulation Hazards

Workers should not be allowed to perform their duties inan excavation in which water is accumulating, unless theappropriate precautions have been taken to remove thewater.

These precautions are as follows:

Properly functioning water-removal equipment.

Excavations that are subject to runoff.


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Hazardous or Toxic Atmospheres

Before allowing a worker to enter an excavation that is 4feet or more deep or that could reasonably be expectedto have a hazardous atmosphere, a competent personmust test the atmosphere.

If a hazardous condition is determined to exist, workers

must use the appropriate respiratory protection devicesand ventilation of the excavation must be undertaken.

Emergency rescue equipment must be made readilyavailable 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.


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What's wrong with thispicture?


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What's wrong with thispicture?

He is working alone at the bottom ofalmost 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, andno shielding of the worker.


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CASE STUDY:

"OSHA Proposes $210,000 in PenaltiesFollowing 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 theinvestigation of a fatal accident at a Clay, Ala.,

construction site. OSHA began an inspection at theSteeple Chase subdivision after being notified that aworker was trapped in a collapsed trench. Rescueattempts failed.


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Agency investigators determined that employees had beenworking in an 18-foot-deep trench with excavated soil piled10 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 bucketand then jump into trenches; failing to provide employeeswith adequate means to enter and exit trenches; placing

excavated materials within two feet of trench walls;inadequately shoring and sloping trench walls, and failing toconduct daily inspections and remove employees from thesite when hazardous conditions were observed.

OSHA also issued four serious citations, with proposedpenalties of $14,000, for allowing employees to work undersuspended loads of sewer pipes and for failing to trainemployees and provide them with hard hats, drinking waterand bathroom facilities.


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Subpart Q

Subpart Q covers the requirements andrelated safety practices for concreteconstruction and masonry work.

It contains the following sections: 1926.700 to 1926.706


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General Requirements and RelatedSafety Practices for Concrete Work

OSHA specifies requirements and safe practices thatapply to all types of concrete work. The generalrequirements are:

Before any type of load can be placed on a concretestructure or any concrete portion of a structure anindividual qualified in the field of structural design mustdetermine that the structure or the portion of a structurebeing used can support the load.

Workers involved in tying or placing reinforcing steel at

heights of 6 feet or more above any working surface mustwear the appropriate fall protection devices.

When reinforcing strands are tensioned at the job site,workers should not be allowed behind the jack during thetensioning process.


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Concrete buckets must be equipped with safety latchesto prevent accidental or premature dumping. Workersshould 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.


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Concrete Equipment and Tools

General requirements for the concrete equipment andtools are summarized as:

Equipment such as saws, mixers, screens and pumpsmust be properly locked out and tagged out before

workers are allowed to perform routine maintenanceduties on them.

Concrete mixers with loading skip of 1 cubic yard orlarger 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 thatactivates if the operator releases the handles.


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Concrete pumping systems that use pipes fordischarging the concrete must be equipped with pipesupports that are rated for at least 100 percentoverload.

Workers who use a pneumatic hose to apply cement,sand or water mixture must wear appropriate headand face protection.

Masonry saws must be equipped with a guard over

the blade and a method for retaining blade fragments.

Concrete Equipment and Tools


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Cast-In-Place Concrete: Requirementsand Related Safety Practices

The term cast-in-place meansthat the concrete is poured(cast) at the job site (in place)into forms that are constructedor assembled at the site.

It involves the followingactivities:

1. Building or assemblingforms

2. Placing rebar into theforms.

3. Pouring concrete

4. Treating the surface of theconcrete.


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Requirements and safety practices forcast-in-place concrete

Forms must be designed and built to withstand allvertical and lateral loads that might be applied to them.

Shoring equipment must be inspected before erection toensure that it meets the specifications set forth in the

engineering drawings.

Reinforcing bars for vertical components of the structuremust be properly supported to prevent overturning orcollapse.

Forms and shores must remain in place until it has beendetermined by a standard test approved by the ASTMthat the concrete has cured sufficiently to support its ownweight and that of any superimposed loads


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Pre-Cast Concrete: Requirements andRelated Safety Practices

Pre-cast concrete is poured in forms at a location off theconstruction.


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Pre-Cast Concrete: Requirements andRelated Safety Practices

The most common uses of pre cast concreteconstruction bridges, parking garages, commercialbuildings and multi-story residential building

Pre-cast concrete components must be properly

supported until they are permanently attached to preventoverturning or collapse.

Lifting mechanisms must be capable of supporting atleast five times the anticipated load.

Workers should not be allowed to work under pre-castcomponents that are in the process of being erected.


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Lift-Slab Concrete: Requirements andRelated Safety Practices

Lift-slab concrete operations involve fabricating pre-castconcrete components with lifting hardware embedded inthem.

Jacks and other equipment used to lift the slabs must be

clearly marked to show the manufacturers specificationsfor lift capacity.

Jacking and lifting equipment must be able to support atleast 2 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 allowthe operator to keep the slab level to within prescribed

tolerances.


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Masonry Construction: Requirementsand Related Safety Practices

Masonry involves the use of bricks orblocks as the primary building material.

Stability is an issue with masonryconstruction. Consequently masonry walls

more than 8 feet in height must besupported to prevent collapse.

Bracing used to support a masonry wallunder construction must remain in placeuntil permanent supporting elements of

the structure are in place. In addition tobracing, a limited access zone must beestablished wherever a masonry wall isbeing constructed.


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Subpart R

Subpart R covers the requirements andrelated safety practices for structural steelconstruction and assembly.



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Structural Steel Construction

Steel construction is a specialized field within thebroader field of construction. It has its own uniquehazards, which result in an average of 35 deaths and2300 lost time injuries every year.

The hazards most commonly associated with steelerection work include working under loads; hoisting,landing, and placing decking and steel joists; columnstability; double connections; and falling to lower levels.

-


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, -Plan, and Construction Sequence:Requirements and Related Safety

Practices

Steel erection cannot begin until the concrete used infootings 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 beimposed during erection.

There must also be sufficient room for operation.

There must be adequate roads into and through theconstruction site


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Hoisting and Rigging: Requirementsand Related Safety Practices

Cranes used in steel erection must undergo a thoroughvisual inspection before each shift to ensure that allcontrols and mechanisms are in proper and safe workingorder.

The capacity of must have a safety factor of at least 5:1.


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Column Anchorage: Requirements andRelated Safety Practices

OSHAs SteelErection Standardrequired that allcolumns be

anchored by aminimum of fouranchor bolts.


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Beams and Columns: Requirementsand Related Safety Practices

When beams are being secured to columns, they mustnot be released from the hoisting lines until secured byat least two bolts per connection.

One of the more hazardous tasks for steel erectionworkers is making double connections.


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Falling Object: Requirements andRelated Safety Practices

Objects falling from a higherlevel and injuring employeesworking at a lower level is aconcern in steel erection.

Consequently, the SteelErection Standard requiresthat all materials, equipment,

and tools used by workerswho are aloft be properlysecured against falling.


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Fall Protection: Requirements andRelated Safety Practices

Falls from higher to lower levels represent the greatesthazard in steel erection.

Consequently, OSHA requires fall protection foremployees working at heights greater than 15 feet.


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Training: Requirements and RelatedSafety Practices

OSHA requires that personnel who work in steel erectionhave 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 protectionsystems;

procedures for preventing falls through holes andother openings;

S b t S


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Subpart S Subpart S covers the construction of

underground tunnels, shafts, chambers and

passageways.


Underground Construction:


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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.

Safety Instruction


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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 evacuationplans.

Access and Egress Employers are required to provide safe access and egress to

underground construction sites.

Unauthorized entry must be both prohibited and prevented.


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Check In and Check Out Procedures

Employers must use an appropriate check-in and check-outprocedure to keep track of employees who work

underground.

Gassy Operations

In underground construction work there are potentially gassy

operations and confirmed gassy operations. Safetyprecautions for gassy operations include the following as aminimum:

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.


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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 potentiallyhazardous gasses.

Ventilation

Contractors are required to provide an adequate supply offresh air to all underground sites.

Illumination

Contractors are required to provide proper illumination in allunderground sites. When explosives are to be handledunderground, a distance of 50 feet must be maintainedbetween any heading and the lighting.


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Fire Prevention and Control

Open flames and fires are prohibited in undergroundconstruction sites. Smoking should be discouraged in

underground sites.

Hot Work

When performing hot work in underground,

noncombustible barriers must be installed in or over ashaft.

Emergencies

Rescue teams or services must be provided atconstruction sites in which 25 or more employees workunderground. A designated person must be available tocall for emergency assistance and to maintain an accuratehead count of those working underground.

C i R i d R l d


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Caissons: Requirements and RelatedSafety Practices

A Caisson is an airtight andwatertight structure in whichconstruction work can bedone underground or

underwater. If a caisson is to be

suspended at any time whenwork is being done in it and

the bottom of the excavationis 9 feet or more, a shieldmust be erected to protectemployees.

C ff d R i d


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Cofferdams: Requirements andRelated Safety Practices

A Cofferdam is a watertightenclosure that can be pumpeddry so that constructionactivities can take place.

A means must provide toprevent flooding if overtoppingof the cofferdam by highwaters is possible.

At least two means of rapidexit must be provided withcofferdams.

C d Ai R i t d


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Compressed Air: Requirements andRelated Safety Practices

Any time work is beingdone undercompressed air, theremust be at least one

competent personreadily available who isfamiliar with all aspectsof working in these

conditions.

Fig: Tunneling inCompressed air without

a shield.

S b t T


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Subpart T

Subpart T covers the requirements and related safetypractices for demolition.

It contains the following section: 1926.850 to 1926.860


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Preparatory Operations

A critical first step before undertaking a demolitionoperation is to obtain a comprehensive engineeringsurvey of the structure that is to be demolished. Thissurvey helps to guard against premature or unplannedcollapse of the structure in question.

Once the engineering survey has been completed, allutilities (gas, electricity and other energy sources) aredisconnected 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 thesite.


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Subpart U

It covers the requirements for blasting and the use ofexplosives on construction sites.

It contains the following 1926.900 to 1926.914

Bl ti G l P i i d


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Blasting: General Provisions andRelated Safety Practices

All types of heat and spark producing devices areprohibited near explosives.

Explosives that are not being used must be stored in alocked magazine.

All explosives must be counted for at all times. Blasting operations conducted above ground should be

completed during daylight hours.

Blasting: General Provisions and


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Blasting: General Provisions andRelated Safety Practices

No person is allowed to handle explosives while underthe influence of drugs.

Warning signs should be prominently displayed to warnagainst the use of radio transmitters within 1000 feet ofthe blasting site

Other Req irements in Blasting


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Other Requirements in BlastingOperations

Before beginning the

preparations for blasting,contractors should postwarning signs that explainthe code of blasting

signals around the blastingarea. Initiating devicesmay not be stored in thesame area with otherexplosives.

Other Requirements in Blasting


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Initiating devices may not be stored in the same areawith other explosives.

There is to be no smoking within 50 feet of explosivesand detonators.

Other Requirements in Blasting


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Avoid the use of electric blasting caps in any area whereextraneous electrical charges might be present thatcould cause an unplanned detonation.

Before initiating detonation, the blaster in charge makes

sure that all extra explosives, detonators, and otherextraneous materials have been removed from the blastarea and properly stored.

No attempt can be made to remove an unexploded

charge. It must be re-primed and re-detonated, orwashed out with water.

R f


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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=4DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138

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
http://www.osha.gov/SLTC/etools/construction/images/rebar_1.jpghttp://mattgray.org/trips/2004/weminuche/photos/ore_bucket_sky.jpghttp://www.buildstore.co.uk/materials/images/masonryconstructionheader.jpghttp://www.buildstore.co.uk/materials/images/masonryconstructionheader.jpghttp://www.cdc.gov/eLCOSH/docs/d0500/d000533/3.jpghttp://cache.viewimages.com/xc/3333144.jpg?v=1&c=ViewImages&k=2&d=4DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138http://cache.viewimages.com/xc/3333144.jpg?v=1&c=ViewImages&k=2&d=4DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138http://www.geoconsol.com/photos/DFW%20Tunnel%20&%20Pipe.jpghttp://kshitija.files.wordpress.com/2006/07/entry_fig3.gifhttp://www.funnyphotos.net.au/images/building-demolition1.jpghttp://mining.mosaicprojects.net/images/millward_blasting.gifhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://www.jobsitesupply.com/img/cast-in-place_detail.jpghttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://web.dcp.ufl.edu/hinze/OSHA-Subparts-U-Z.htmhttp://mining.mosaicprojects.net/images/millward_blasting.gifhttp://www.funnyphotos.net.au/images/building-demolition1.jpghttp://www.funnyphotos.net.au/images/building-demolition1.jpghttp://www.funnyphotos.net.au/images/building-demolition1.jpghttp://kshitija.files.wordpress.com/2006/07/entry_fig3.gifhttp://www.geoconsol.com/photos/DFW%20Tunnel%20&%20Pipe.jpghttp://cache.viewimages.com/xc/3333144.jpg?v=1&c=ViewImages&k=2&d=4DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138http://cache.viewimages.com/xc/3333144.jpg?v=1&c=ViewImages&k=2&d=4DAA13B573E1BD2FD9DF0C71D94B64A8A55A1E4F32AD3138http://www.cdc.gov/eLCOSH/docs/d0500/d000533/3.jpghttp://www.buildstore.co.uk/materials/images/masonryconstructionheader.jpghttp://www.buildstore.co.uk/materials/images/masonryconstructionheader.jpghttp://mattgray.org/trips/2004/weminuche/photos/ore_bucket_sky.jpghttp://www.osha.gov/SLTC/etools/construction/images/rebar_1.jpg

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