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Trench sloping calculator (OSHA)

By Safety PaperworkBuilt from OSHA standards and guidance · How we write and check theseUpdated

Enter the depth, the width at the bottom and the soil type. The calculator applies the maximum allowable slopes in OSHA 29 CFR 1926 Subpart P, Appendix B, for excavations up to 20 feet deep.

What the result means

  • Type A soil: 3/4 horizontal to 1 vertical (53 degrees).
  • Type B soil: 1 to 1 (45 degrees).
  • Type C soil: 1 1/2 to 1 (34 degrees).
  • Trenches 5 feet or deeper need a protective system unless they are in stable rock. Deeper than 20 feet needs a design by a registered professional engineer.
  • A competent person must classify the soil and inspect the trench daily and after rain.

Tell the crew

Run the excavation and trench safety toolbox talk and get it signed on the phone.

Open the toolbox talk

Sources

More help

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