Excavation Protective Systems

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1. Slide 1

   Protective Systems

   • This material was produced under a grant (SH-31234-SH7) from the Occupational Safety and Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor does the mention of trade names, commercial products, or organization imply endorsement by the U.S. Government.
2. Slide 2

   Objectives:

   • Define Different types of Protective Systems
   • Identify uses and limitations of different protective systems
   • Understand the usage characteristics of different protective systems
   • Understand how to safely implement the protective system
3. Slide 3

   October 2015 through September 2016

   • Standard
   • Citations
   • Inspections
   • Penalty
   • Description
   • Total
   • $2,179,654
   • All Standards cited for Site Preparation Contractors
4. Slide 4

   4 types of Protective Systems

   • Benching- means a method of protecting workers from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near vertical surfaces between levels. Benching cannot be done in Type C soil.
   • Sloping- involves cutting back the trench wall at an angle inclined away from the excavation.
5. Slide 5

   4 types of Protective Systems Continued

   • Shoring- requires installing aluminum hydraulic or other types of supports to prevent soil movement and cave-ins.
   • Shielding- protects workers by using trench boxes or other types of supports to prevent soil cave-ins.
   • Combination- using more than one type of protective system at the same time.
6. Slide 6
   • Benching
7. Slide 7

   How to use Benching

   • Benching can only be used for type A and B soils
   • If it is type C sloping or some other means of protection must be used
   • Benching is cutting into sides of excavations and making stair like shelves into the sides
8. Slide 8

   Benching type a soil

   • All benched excavations 20 feet or less in depth shall have a maximum allowable slope of 3/4 to 1 and maximum bench dimensions as follows
   • MULTIPLE
   • BENCH
   • SIMPLE BENCH
9. Slide 9
   • Sloping
10. Slide 10

    Sloping

    • Sloping or benching for excavations greater than 20 feet deep shall be designed by a registered professional engineer
    • Can be used for every soil type (the slope will vary depending on soil type)
11. Slide 11

    How to determine Sloping

    • SOIL OR ROCK TYPE MAXIMUM ALLOWABLE SLOPES FOR EXCAVATIONS LESS THAN 20 FEET DEEP
    • STABLE ROCK
    • TYPE A (2)
    • TYPE B
    • TYPE C
    • VERTICAL (90⁰)
    • 3/4:1 (53⁰)
    • 1:1 (45⁰)
    • 1 ½:1 (34⁰)
12. Slide 12

    Simple Sloping type a soil

    • simple slope excavations which are open 24 hours or less (short term) and which are 12 feet or less in depth shall have a maximum allowable slope of ½:1.
13. Slide 13
    • Shoring
14. Slide 14

    Timber Shoring

    • Shoring is the provision of a support system for trench faces used to prevent movement of soil, underground utilities, roadways, and foundations.
    • Shoring or shielding is used when the location or depth of the cut makes sloping back to the maximum allowable slope impractical.
    • Shoring systems consist of posts, wales, struts, and sheeting. There are two basic types of shoring, timber and aluminum hydraulic.
15. Slide 15

    Hydraulic Shoring

    • All shoring should be installed from the top down and removed from the bottom up. Hydraulic shoring should be checked at least once per shift for leaking hoses and/or cylinders, broken connections, cracked nipples, bent bases, and any other damaged or defective parts.
16. Slide 16

    Hydraulic Shoring

    • The trend today is toward the use of hydraulic shoring, a prefabricated strut and/or wale system manufactured of aluminum or steel. Hydraulic shoring provides a critical safety advantage over timber shoring because workers do not have to enter the trench to install or remove hydraulic shoring. Other advantages of most hydraulic systems are that they:
    • Are light enough to be installed by one worker;
    • Are gauge-regulated to ensure even distribution of pressure along the trench line;
    • Can have their trench faces "preloaded" to use the soil's natural cohesion to prevent movement; and
    • Can be adapted easily to various trench depths and widths.
17. Slide 17

    Pneumatic Shoring

    • Screw Jacks. Screw jack systems differ from hydraulic and pneumatic
    • systems in that the struts of a screw jack system must be adjusted manually. This creates a hazard because the worker is required to be in the trench in order to adjust the strut. In addition, uniform "preloading" cannot be achieved with screw jacks, and their weight creates handling difficulties.
    • Single-Cylinder Hydraulic Shores. Shores of this type are generally
    • used in a water system, as an assist to timber shoring systems, and in shallow trenches where face stability is required.
    • Underpinning. This process involves stabilizing adjacent structures,
    • foundations, and other intrusions that may have an impact on the excavation. As the term indicates, underpinning is a procedure in which the foundation is physically reinforced. Underpinning should be conducted only under the direction and with the approval of a registered professional engineer.
18. Slide 18

    Pneumatic Shoring continued

    • Installed from the top
    • down, to give the most protection while installing it
    • Made with a series of
    • uprights and horizontals
19. Slide 19

    Sloping and shoring part 1

    • Source: https://www.youtube.com/watch?v=USat6LdENzU
    • This video depicts how to install an shoring system into a trench
20. Slide 20

    Sloping and shoring part 2

    • Source: https://www.youtube.com/watch?v=1Y5lsem9r4U
    • This video depicts how to install an shoring system into a trench
21. Slide 21
    • Shielding
22. Slide 22

    Shielding

    • Trench Boxes are different from shoring because, instead of shoring up or otherwise supporting the trench face, they are intended primarily to protect workers from cave-ins and similar incidents.
    • The excavated area between the outside of the trench box and the face of the trench should be as small as possible.
    • The space between the trench boxes and the excavation side are backfilled to prevent lateral movement of the box.
    • Shields may not be subjected to loads exceeding those which the system was designed to withstand.
23. Slide 23

    How to use Shielding

    • Stacking Trench Boxes
    • Trench box
24. Slide 24

    Use of shielding

    • Top of the trench box
    • needs to be at least 18” above soil level, not the top of the excavation
    • Boxes can be stacked
    • and locked into each other, they need to be compatible to be stacked
    • Ensure no employee is inside trench between a moving object and wall Do not stand under suspended load
25. Slide 25
    • Spoil Piles
26. Slide 26

    Spoil Pile

    • Temporary Spoil
    • Temporary spoil must be placed no closer than 2 ft (0.61 m) from the surface edge of the excavation, measured from the nearest base of the spoil to the cut. This distance should not be measured from the crown of the spoil deposit. This distance requirement ensures that loose rock or soil from the temporary spoil will not fall on employees in the trench.
    • Spoil should be placed so that it channels rainwater and other run-off water away from the excavation. Spoil should be placed so that it cannot accidentally run, slide, or fall back into the excavation
27. Slide 27

    Spoil Pile Continued

    • Permanent Spoil
    • Permanent spoil should be placed at some distance from the excavation. Permanent spoil is often created where underpasses are built or utilities are buried. The improper placement of permanent spoil, i.e. insufficient distance from the working excavation, can cause an excavation to be out of compliance with the horizontal-to-vertical ratio requirement for a particular excavation. This can usually be determined through visual observation. Permanent spoil can change undisturbed soil to disturbed soil and dramatically alter slope requirements.
28. Slide 28

    Improper placement of spoil pile

    • Unsafe placement of spoil pile
    • Unsafe benching
29. Slide 29
    • Hazard identification
30. Slide 30

    Hazard identification 1

    • No safe access or egress
    • No protective system in
    • place
    • Housekeeping in trench
    • Heavy equipment close by
    • No limited access zone
31. Slide 31

    Hazard identification 2

    • No safe access or egress
    • No protective system in
    • place
32. Slide 32

    Hazard identification 3

    • No safe access or egress
    • No protective system in
    • place
    • Housekeeping in trench
    • Heavy equipment close by
    • No limited access zone
33. Slide 33
    • Worker Rights and responsibilities
34. Slide 34

    Employee Rights & Responsibilities Occupational Safety and Health Act of 1970

    • To assure safe and healthful working conditions for working men and women
    • By authorizing enforcement of the standards developed under the Act
    • By assisting and encouraging the States in their efforts to assure safe and healthful working conditions
    • By providing for research, information, education, and training in the field of occupational safety and health…
35. Slide 35

    Employee Rights & Responsibilities

    • You have the right to:
    • A safe and healthful workplace
    • Know about hazardous chemicals
    • Information about injuries and illnesses in your workplace
    • Complain or request hazard correction from employer
36. Slide 36

    Employee Rights & Responsibilities You have the right to:

    • File a confidential complaint with OSHA to have their workplace inspected.
    • Receive information and training about hazards, methods to prevent harm, and the OSHA standards that apply to their workplace. The training must be done in a language and vocabulary workers can understand.
    • Get copies of their workplace medical records and exposure records.
    • Participate in an OSHA inspection and speak in private with the inspector.
37. Slide 37

    Employee Rights &

    • Responsibilities Continued:
    • File a complaint with OSHA if they have been retaliated or discriminated against by their employer as the result of requesting an inspection or using any of their other rights under the OSH Act.
    • File a complaint if punished or discriminated against for acting as a “whistleblower” under the additional 21 federal statutes for which OSHA has jurisdiction.
38. Slide 38

    Whistleblower Protection

    • http://www.whistleblowers.gov/