ExcAVATIONs

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Shoring and shielding Shoring and shielding systems can prevent cave-ins in excavations with or without sloped or benched faces. The safest way to install and remove them is from outside the excavation. Shores are vertical or horizontal supports that prevent the faces of an excavation from collapsing. Vertical shores are called uprights. They’re easy to install, relatively inexpensive, and often used in stable soil or in shallow excavations that have parallel faces. Vertical shores must be sized for the excavation’s dimensions and soil type. Horizontal shores are called walers. Walers are often used when unstable soil makes sloping or benching impractical and when sheeting is necessary to prevent soil from sliding into the excavation. Shields provide employees a safe work area by protecting them from collapsing soil. Shields don’t prevent cave-ins but “shield” workers if a face does collapse. They are usually placed in the excavation by heavy equipment. Shoring and shielding systems are available from manufacturers in a variety of dimensions, usually aluminum or steel, or they can be custom-built from tabulated data approved by a registered professional engineer. Manufacturers will also provide tabulated data with their systems that includes engineering specifications, depth ratings, special instructions, and system limitations. Only by carefully studying and understanding the manufacturer’s tabulated data can the competent person choose the correct protective system. 16
What do shores and shields look like? Horizontal shore Photo credit: Speed Shore Corp. Trench shield 17 Vertical shore Photo credit: Speed Shore Corp. Photo credit: Speed Shore Corp.
Page 1 and 2: Exca v ations Safe practices for sm
Page 3 and 4: About this document Excavations - S
Page 5 and 6: Introduction A cave-in can trap you
Page 7 and 8: What is a trench? A trench is deepe
Page 9 and 10: The role of the competent person A
Page 11 and 12: Soil and stability Some soils are m
Page 13 and 14: Manual tests Manual testing involve
Page 15: What do benched slopes look like in
Page 19 and 20: Materials and mobile equipment Exca
Page 21 and 22: Water accumulation Water makes soil
Page 23 and 24: Where do I post the warning signs?
Page 25 and 26: • Never use damaged chains or fra
Page 27 and 28: Stability and adjacent structures M
Page 29 and 30: Safe practices checklist All your a
Page 31 and 32: 16. Underground installations are p
Page 33 and 34: 35. Appropriate sloping, shoring, o
Page 35 and 36: Registered professional engineer A
Page 37 and 38: Notes 37
Page 40: 440-2174 (4/09) OR-OSHA

ExcAVATIONs

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