Managing Costs through Partnerships

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1 Safety Guideines for Excavation INTRODUCTION Excavation work can be a very hazardous exposure to empoyees and other contractors on construction job sites. Excavation is one of the most hazardous construction operations. The most feared hazard is excavation cave-in. Most accidents occur in trenches 5-15 feet deep. There is usuay no warning before a cave-in, but there are signs of potentia hazards and contros that can be impemented. In addition to cave-ins, there are other potentiay dangerous exposures such as asphyxiation due to ack of oxygen, inhaation of toxic materias, moving machinery near the edge of an excavation resuting in coapse, water intrusion, and accidenta severing of underground utiity ines. The safety guideines in this buetin are provided to assist safety efforts in identification of hazards, protective systems to be used and safety procedures to be impemented in an effort to protect a construction workers. These guideines are for excavations of ess than 20 feet. Excavation safeguards for excavations of over 20 feet shoud be designed by a registered professiona engineer. SCOPE AND APPLICATION The Occupationa Safety and Heath Administration s (OSHA) rues appy to a open excavations made in the earth s surface, which incudes trenches. According to OSHA (b), a trench is referred to as a narrow excavation (in reation to its ength) made beow the surface of the earth. In genera, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet. GENERAL SAFETY REQUIREMENTS Pre-job panning Many of the job site accidents are a resut of inadequate panning prior to work at the site commencing. Prior to arriva at the job site, key personne shoud review the scope of the work to be competed, as we as identify potentia site specific hazards. Key personne, incuding identified competent persons at each job, shoud be invoved in a panning. The job site panning and evauation shoud incude utiity ines that may run through the site and who wi be responsibe for a utiity ocates to be competed prior to arriva at the job. Evauation and pans shoud be made for both overhead and underground ines. Soi conditions shoud be evauated and pans in pace for specific soi types that may be encountered and where excavation wi be competed. Protective equipment incuding shoring, if required, shoud be identified and provided at the site. Surface and ground water/water tabe shoud be reviewed at the site and pans estabished to dea with potentia hazards. Traffic patterns shoud be evauated, incuding proximity to the excavation site and incude pans for traffic contro both into and out of the site. Managing Costs through Partnerships United Fire Group 118 Second Avenue SE PO Box Cedar Rapids, Iowa unitedfiregroup.com LC-7095 (03-11) PAGE 1OF 5

2 Any structures on the site shoud be reviewed and incude proximity to a excavation areas, as we as their condition. If basting is to be competed, procedures and pans shoud be outined and estabished pre-job and during construction. Empoyee training shoud be provided pre-job for a empoyees who wi be invoved in excavation operations. CONSTRUCTION JOB SITE SAFETY Competent person(s) Competent persons shoud be identified and in pace at the time the job starts. The competent person shoud be responsibe for evauation of soi conditions, potentia hazards and methods to be impemented to contro the hazards. Daiy inspections shoud be competed by competent persons of the excavation site and adjacent areas subject to cave-in, faiures of protective systems and equipment, potentiay hazardous atmospheres, and other hazardous conditions. The competent person shoud be given authority to hat construction unti adequate safeguards can be impemented. Reference 29 CFR (k) Daiy inspections of excavations, the adjacent areas, and protective systems sha be made by a competent person for evidence of a situation that coud resut in possibe cave-ins, indications of faiure of protective systems, hazardous atmospheres, or other hazardous conditions. An inspection sha be conducted by the competent person prior to the start of work and as needed throughout the shift. Inspections sha aso be made after every rainstorm or other hazard increasing occurrence. These inspections are ony required when empoyee exposure can be reasonaby anticipated. Where the competent person finds evidence of a situation that coud resut in a possibe cave-in, indications of faiure of protective systems, hazardous atmospheres, or other hazardous conditions, exposed empoyees sha be removed from the hazardous area unti the necessary precautions have been taken to ensure their safety. PROTECTION OF EMPLOYEES Empoyees shoud be protected from cave-ins by using an adequatey designed protective system. Protective systems must be abe to resist a expected oads to the system. Severa factors come into pay when deveoping a tota protective system. The design of the system itsef, how materias and equipment are handed in and around the excavation, and instaation and remova of protective system components are a part of the tota protective system. Reference CFR (a) Protective system is a method of protecting empoyees from cave-ins, from materia that coud fa or ro from an excavation face or into an excavation, or from the coapse of adjacent structures. Protective systems incude support systems, soping and benching systems, shied systems, and other systems that provide the necessary protection. DESIGN OF PROTECTIVE SYSTEMS The empoyer sha seect and construct sopes and configurations of soping, benching systems, support systems, shied systems, and other protective systems. Soping: Form sides of an excavation that are incined away from the excavation. Shoring: Such as meta hydrauic, mechanica or timber shoring system that supports the sides. Shied: Can be permanent or portabe. Aso known as trench box or trench shied. United Fire Group Loss Contro Services LC-7095 (03-11) PAGE 2 OF 5

3 Reference , (b), (c) Soping/benching are the methods of excavating the sides of a trench to form one or a series of horizonta eves or steps, usuay with vertica or near-vertica surfaces between eves. One method of protective empoyees in excavations is to sope the sides to an ange not steeper than one and one-haf the horizonta to one vertica (34 degrees measured from the horizonta). This maximum aowabe sope is suitabe for a soi types and excavations ess than 20 feet deep. Soi cassifications and maximum aowabe sopes for Stabe Rock, Type A, B and C sois can be found in CFR 1926 Subpart P, Appendix B, Tabe B-1 Maximum Aowabe Sopes. Shoring or shieding is used when the ocation or depth of the cut makes soping back to the maximum aowabe sope impractica. There are two basic types of shoring: timber and auminum hydrauic. Contractors may use a shied or trench box that is either designed or approved by a registered professiona engineer or is based on tabuated data prepared or approved by a registered professiona engineer. Auminum, timber or other suitabe materias may aso be used. Trench boxes (shieding) are different from shoring because instead of supporting the trench face, they are mosty used to protect workers from cave-ins. The excavated area between the outside of the trench box and the face of the trench shoud be as sma as possibe. The space between the trench box and the excavation side may be backfied (or other means may be used) to prevent atera movement of the box. Shieds may not be subjected to oads exceeding those which the system was designed to withstand. Trench boxes may be used in combination with soping and benching. OSHA permits the use of a trench shied as ong as the protection provided is equa to or greater than the protection that woud be provided by the appropriate shoring system. The empoyer is free to choose the protective method they fee is most appropriate for the particuar circumstance. Once the protective method has been chosen, the required performance criteria shoud be met by that system. The standard does not require the instaation and use of protective system when an excavation is made in entirey stabe rock as determined by the competent person or when the excavation is ess than 5 feet deep and the competent person has determined there is no indication of a potentia cave-in. INSTALLATION AND REMOVAL OF PROTECTIVE SYSTEMS The equipment members shoud be securey connected, safey instaed and never overoaded. Excavations under the protective system shoud be 2 feet or ess beow the bottom members of the support or shied system in the trench if the system is designed to resist trench forces to the bottom of the trench and there is no indication of a possibe cave-in beow the bottom of the support system, whie the trench is open. As soon as work is competed, the excavation shoud be backfied as the protective system is removed or dismanted. Once the excavation is ceared, the workers shoud sowy remove the system from the bottom up, taking care to sowy reease a supporting members. United Fire Group Loss Contro Services LC-7095 (03-11) PAGE 3 OF 5

4 MATERIALS AND EQUIPMENT The empoyer is responsibe to ensure that a materia and equipment that is used is free from materia defect that coud ead to a faiure resuting in a trench coapse. Materias and equipment shoud be used foowing a manufacturer s recommendations and specifications. Competent persons shoud inspect a equipment daiy to ensure that it is free of defect and suitabe for continued use. Defective equipment, if identified, shoud be documented/tagged/removed and repaced prior to continuing excavation work. Materias or equipment may not be returned to use uness evauated by a registered professiona engineer. ADDITIONAL HAZARDS Access and egress The empoyee must provide safe access to and from a excavation sites. When empoyees are required to be in a trench greater than 4 feet deep or more, the empoyee shoud be provided with adequate means of exit such as adders, steps, ramps or other safe means of access or egress. Means of access or egress shoud be within 25 feet of atera trave. If ramps are used, they must be designed by a competent person or structura engineer if vehices are used on the ramps. Structura members of ramps used for access or egress shoud be of uniform dimension and connected in manner so that they wi not cause tripping or dispacement. Fas and equipment In addition to cave-in hazards, there are other hazards associated with excavation operations. Hazards incude faing oads/ objects, fas from eevation and mobie equipment on site. The foowing precautions shoud be taken to protect workers from these hazards. Maintain materias or equipment that might fa or ro into an excavation a minimum of 2 feet from the edge of the excavation or have retaining devices or both. This woud incude spoi pies and equipment such as additiona buckets, etc. Warning systems such as hand signas, barricades and stop ogs can be provided to aert operators of the excavation edge. Scaing can be competed to remove oose rock or soi, or insta protective barricades to protect empoyees from faing rock, soi or materias. Empoyees shoud not be aowed to work on faces or sopes of excavations above other workers uness workers at ower eves are adequatey protected from a types of faing materias. Empoyees shoud be prohibited from working under oads handed by digging or ifting equipment. Empoyees shoud be required to stand away from vehices being oaded or unoaded. Water accumuation Empoyees shoud be prohibited from working in excavations where water has accumuated, or is accumuating, uness adequate precautions have been taken. If water remova equipment is used to remove water that has accumuated, or is accumuating, the competent person shoud monitor the operations of the equipment to ensure proper use. United Fire Group Loss Contro Services LC-7095 (03-11) PAGE 4 OF 5

5 Diversion ditches, dikes or other suitabe methods shoud be used to prevent surface water from entering the excavation and to provide adequate drainage of the area adjacent to the excavation. The competent person shoud inspect excavations to runoffs from heavy rains. Hazardous atmospheres A competent person shoud test excavations greater than 4 feet in depth, as we as ones where oxygen deficiency or a hazardous atmosphere exists or coud be reasonaby expected to exist before any empoyee enters the excavation area. If a hazardous atmosphere exists, proper persona protective equipment or ventiation must be provided. Empoyee training of any persona protective equipment shoud be documented. Contros used shoud be reguary evauated by competent persons. If hazardous atmospheres are determined to exist, the empoyer must provide emergency rescue equipment on site to incude, but not imited to: breathing apparatus, safety harness and ine, basket/stretcher, defibriator. Training must be provided to a empoyees who may be designated as an emergency responder. Vehice and mobie equipment traffic Vehice traffic into, around the site and exiting the site shoud be evauated. Signing shoud be provided to indicate access/exit points, aowabe speed imits and traffic patterns desired. Fagmen shoud be provided as determined is necessary to contro the fow of vehices at the site. Safety vests, which are highy visibe, shoud be provided for a empoyees and contractors on site. Predetermined aowabe distances to the edge of a excavations shoud be monitored and enforced. Traffic patterns and signage shoud be evauated each day by competent persons to ensure desired contros remain in pace. SUMMARY There are serious potentia hazards to empoyees who are invoved in trenching and excavation operations. The greatest risk is that of cave-in. Cave-in accidents, once they occur, are more ikey to resut in fataities than other construction reated accidents. By foowing strict rues and guideines estabished by OSHA and your company, the identification of key empoyees and competent persons, as we as documented empoyee training, can hep avoid these incidents. United Fire Group oss contro personne are avaiabe to you with technica assistance as outined in the Loss Contro Guideines and Best Practices. If further assistance is required, pease ca or e-mai us at mwosscontro@unitedfiregroup.com. RELATED REFERENCES CFR 1926 Subpart P Excavations United Fire Group Loss Contro Services The information contained in this service buetin was obtained from reiabe sources. However, United Fire Group accepts no ega responsibiity for the correctness or competeness of this information. LC-7095 (03-11) PAGE 5 OF 5