Excavation Safety Program

Transcription

1 Excavation Safety Program Excavation, Trenching & Shoring Safety I. Purpose The purpose of this policy is to establish safe operating procedures for any earthwork or underground work that is done on a job site. It is to ensure the safety of personnel who are required to enter/work in excavations and trenches that are 5 0 or deeper, and to maintain compliance with the applicable OSHA regulations. However, these standards should be applied to hazardous locations less than 5 0. II. Special Requirements A. Competent Person All earthwork in excavations and trenches will be overseen by a competent person at all times. OSHA s definition of a competent person is One who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees; and who has authorization to take prompt corrective measures to eliminate them. A competent person within the organization would include, but is not limited to, a designated foreman, and/or executive management. B. Preplanning Prior to beginning any earthwork, the foreman and competent person are required to review the job for the primary hazardous exposures to workers and the public. Exposures include, but are not limited to the following: surface hazards or encumbrances; underground installations; means of access or exit from trenches or excavations; exposure to vehicular traffic; exposure to falling loads; warning system for mobile equipment; hazardous atmospheres; contaminated soil; emergency rescue equipment; water accumulation; stability of adjacent structures; protection from loose rocks or soils; fall protection; support systems; and materials and equipment. C. Underground Installations 1. Prior to beginning any excavation, the Regional Notification Center, Underground Alert, will be called to assist in the location of utility installations. 2. The Regional Notification Center and all owners of underground facilities in the area who are not members of the Notification Center must be advised of the proposed work at least two working days prior to the start of any digging or excavation work, except in the case of emergency repair work. 3. Prior to opening an excavation, efforts shall be made to determine whether underground installations; i.e., sewer, telephone, water, fuel, electrical lines, etc., will be encountered, and if so, where such underground installations are located. Revised: December 2009 Page 1 of 6

2 4. The exact location and depth of these lines will be marked by stakes indicating the type of service. After all underground services have been checked and marked, work may begin at the direction of the competent person. D. Access & Egress 1. Structural Ramps If structural ramps are to be used as a means of access and egress, they must be designed by a competent person and constructed in accordance with the design. 2. Means of Egress A stairway, ladder, ramp, or other safe means of egress will be located in trench excavations that are 4 0 or more in depth, and will be located so as to require no more than 25 0 of lateral travel by employees. E. Vehicular Traffic Employees exposed to vehicular traffic shall be provided with and shall wear a reflectorized highly visible warning vest. F. Exposure to Falling Loads No person shall be permitted under loads handled by lifting or digging equipment including power shovels, derricks, or hoists. Employees will be required to stand away from any vehicle being loaded or unloaded to avoid being struck by any spillage or falling materials. Operators may remain in the cabs of vehicles being loaded or unloaded when the vehicles are equipped to provide adequate protection for the operator during loading and unloading operations. G. Warning System Mobile Equipment When mobile equipment is utilized or allowed adjacent to excavations, substantial stop logs or barricades shall be installed. If possible, the grade should be away from excavation. If it is necessary to place or operate power shovels, trucks, materials, or other heavy objects on a level above and near an excavation, the side of the excavation shall be sheet-piled, shored, or braced as necessary to resist the extra pressure due to such superimposed loads. H. Hazardous Atmospheres 1. Testing and Controls In addition to the requirements set forth in the CAL/OSHA safety orders, for both construction and general industry, the following requirements will apply: Testing for oxygen deficiency (19.5% minimum) or hazardous atmosphere will be performed in any excavation greater than 4 0 in depth, or at any depth where employees are doing hand work or repairs within the walls of any trench, where the above conditions exist or could reasonably be expected to exist, such as in areas of contaminated soils or areas where hazardous substances are stored nearby. 2. Adequate Precautions The following precautions will be taken to prevent employee exposure to hazardous atmospheres: a. Provide proper respiratory protection or ventilation where exposure to atmospheres containing less than 19.5% oxygen and/or other hazardous atmospheres exists; Revised: December 2009 Page 2 of 6

3 b. Provide proper ventilation to prevent exposure to atmospheres containing a concentration of flammable gas in excess of 20% of the lower flammable limit of the gas; c. When any of the above controls are used, periodic retesting of the atmosphere will be conducted as often as necessary to ensure the atmosphere remains safe. I. Emergency Rescue Equipment 1. Emergency rescue equipment, such as, breathing apparatus, a safety harness and lifeline, or a basket stretcher, must be readily available where hazardous atmospheric conditions exist or may reasonably be expected to develop during work in an excavation. 2. Emergency rescue equipment, when required, will be attended when in use by a safety watch. 3. Prior to entry into any deep and confined footing excavations, bell-bottom pier holes, or other similar deep holes, employees are required to wear a harness with a lifeline securely attached to it. The lifeline must be separate from any line used to handle materials, and must be individually attended by a safety watch at all times while an employee is in the excavation with this equipment. J. Water Accumulation 1. Employees are not permitted to work in excavations where there is an accumulation of water or where water is accumulating, unless adequate precautions have been taken to protect the employees against the hazards. Special precautions which can be taken include, but are not limited to, a special support or shield system to protect from cave-ins, water removal to control the level of accumulating water, and use of a safety harness and lifeline. 2. When water removal equipment is used to prevent or control the water from accumulating, the equipment and operations will be monitored by the competent person to ensure proper operation. 3. Diversions, ditches, dikes, or other suitable means will be used to prevent surface water from entering an excavation and to provide adequate drainage of the area adjacent to the excavations. Any excavation subject to runoff from heavy rains will require an inspection by a competent person and compliance with the above (1 & 2). K. Stability of Adjacent Structures 1. If the stability of adjoining buildings or walls is endangered by excavation operations, support systems such as shoring, bracing, or underpinning must be provided as necessary to ensure the stability of such structures for the protection of employees safety. Such shoring, bracing, or underpinning shall be inspected daily or more often, as conditions warrant by a competent person and the protection effectively maintained. 2. Except in hard rock, excavations below the level of the base footing of any foundation or retaining wall is not permitted, unless the wall is provided with a support system such as underpinning to ensure the safety of employees and the stability of the structure. 3. Sidewalks, pavements, and appurtenant structures are not permitted to be undermined unless a support system or another method of protection against collapse is provided for the safety of employees. Revised: December 2009 Page 3 of 6

4 L. Loose Rock or Soils 1. Adequate protection must be provided to protect employees from loose rock or soil that could pose a hazard by falling or rolling from an excavation face. Protection may consist of scaling to remove loose material; installation or protective barricades at intervals as necessary on the face to stop and contain falling material; or other means that provide equivalent protection. 2. Sides of trenches in unstable or soft material, 5 0 or more in depth, shall be shored, sheeted, braced, sloped, or otherwise supported by means of sufficient strength to protect the employees working within them. 3. Excavated or other materials must be placed at least 2 0 from the edge of excavations, or by the use of retaining devices that are sufficient to prevent materials or equipment from rolling into excavations, or a combination of both methods if necessary. M. Inspections 1. At the start of work and as needed throughout the shift; 2. After every rain storm or other hazard increasing occurrence; 3. These inspections are only required when employee exposure can be reasonably anticipated. When there is evidence of a situation that could result in a possible cave-in, indications of a failure in the protective systems, a hazardous atmosphere has developed, or other hazardous conditions are found, all employees must be removed from the hazardous area until the necessary precautions have been taken to safeguard employees. N. Fall Protection Where employees or equipment are required or permitted to cross over excavations, walkways or bridges, standard guardrails must be provided. Adequate barricades providing physical protection shall be provided at all excavations. All wells, pits, shafts, etc., shall be barricaded and covered. Upon completion of operations, temporary wells, pits, shafts, etc., shall be backfilled. O. Barricades Types of excavations and trenches 4 0 or deeper must be shored or sloped back to angle of repose in compliance with OSHA requirements. All open trenches and excavations must be barricaded. 1. Excavations (trenches) requiring wooden barricades constructed with 2 x4 rail at 42 in height and 2 x4 mid-rail, including 2 x4 uprights no further than 3 0 apart are: a. Any excavation to be opened for more than 48 hours; b. Any excavation that cuts an accepted established walkway, sidewalk, or aisle way. 2. Excavations requiring saw horse-type barricades with flashing lights are any excavation in or cutting an accepted established nonpublic roadway or walkway, or temporary roadway where vehicles may travel. 3. All excavations (trenches) not covered by 1 or 2 above must be barricaded with yellow and black barrier tape, erected at approximately 42 high with uprights no further apart than All excavations on public streets require that they be completely covered prior to leaving the site at the end of the work shift. If natural cover is not possible, steel plates anchored to the street with asphalt nosing shall be employed. Revised: December 2009 Page 4 of 6

5 III. Requirements for Protective Systems A. Protection of Employees in Excavations 1. Each employee in an excavation will be protected from cave-ins by an adequate protective system designed in accordance with applicable standards and the Section B below except when: a. Excavations are made entirely in stable rock; b. Excavations are less than 5 0 in depth and examination of the ground by a competent person provides no indication of a potential cave in. 2. Protective systems must have the capacity to resist, without failure, all loads that are intended or could reasonably be expected to be applied or transmitted to the system. B. Design of Sloping and Benching Systems The slopes and configurations of sloping and benching systems are to be selected and constructed in accordance with the requirements of this policy and the appropriate standards as listed below: 1. Excavations are to be sloped at an angle not steeper than one and one-half horizontal to one vertical (34 degrees measured from the horizontal) unless one of the following options are used: a. Option #1: Use Appendices A & B to determine the proper slopes and configurations; b. Option #2: Slopes and configurations are designed using written tabulated data such as tables and charts, to include the identification of the parameters that affect the selection of a sloping or benching system including its limit of use, size and configuration to be safe, and the necessary information to aid in selecting a correct system approved by a Registered Professional Engineer, and a copy of the approved data is maintained at the job site during construction, and a copy made available to the enforcing agency upon request c. Option #3: Design by a Registered Professional Engineer in written form to include calculations, magnitude, and configurations determined to be safe for the project, with a copy to be maintained at the job site, and one made available to the enforcing agency upon request. C. Design of Support Systems, Shield Systems, and other Protective Systems If used, these systems are to be designed in accordance with the requirements of the State and/or Federal Construction Safety standards. D. Materials and Equipment 1. All materials and equipment used for protective systems is to be free from damage or defects that might impair their proper function, and used and maintained according to manufacturer s specifications. 2. When material or equipment is damaged, the company s competent person will examine it for approval, for suitability and continued use. E. Installation and Removal of Support Systems 1. General a. Members of support systems must be securely connected together to prevent sliding, falling, kick-outs, or other predictable failure. Revised: December 2009 Page 5 of 6

6 b. Support systems must be installed and removed in a manner that protects employees from cave-in, structural collapses, or from being struck by members of the support system. c. Individual members of support systems must not be subjected to loads exceeding those which the members were designed to withstand. d. Before temporary removal of individual members begins, additional precautions must be taken to protect employees, such as installing other structural members to carry the loads imposed on the support system. e. Removal must begin at, and progress from, the bottom of the excavation. Members must be released slowly and carefully removed so as to note any indication of possible failure of the remaining members of the structure of possible cave-in of the sides of the excavation. f. Backfilling must progress together with the removal of support systems from excavations. 2. Additional requirements for support systems for trench excavations. a. Excavation of material to a level no greater than 2 0 below the bottom of the members of a support system will be permitted, but only if the system is designed to resist the forces calculated for the full depth of the trench, and there are no indications while the trench is open of a possible loss of soil from behind or below the bottom of the support system; b. Installation of a support system must be closely coordinated with the excavation of trenches. F. Sloping and Benching Systems Employees are not permitted to work on the faces of sloped or benched excavations at levels above other employees except when employees at the lower levels are adequately protected from the hazards of falling, rolling, or sliding material or equipment. G. Shield Systems Should a shield system be used on any job, it must be designed for the job requirements and approved safety procedures followed. IV. Permits Prior to the start of any work which involves substantial risk of injury, a permit may be required from the enforcing agency. CAL/OSHA requires both an annual permit and job permits for certain work. Such is the case for all trenches or excavations which are 5 0 or deeper. Revised: December 2009 Page 6 of 6