Core TradesQuestion 56 of 700

For an excavation made in soft or unstable (Type C) soil, the MAXIMUM allowable slope (horizontal to vertical) is generally:

a.1/2 to 1
b.1-1/2 to 1
c.1/4 to 1
d.3 to 1

Explanation

Type C soil, being the least stable, must be laid back to a maximum slope of 1-1/2 horizontal to 1 vertical (about 34 degrees). Steeper ratios like 1/2:1 or 1/4:1 are unsafe for Type C, and 3:1 is flatter than required.

Law Reference: Cal/OSHA Title 8 (Excavations)

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