3304.4.2 Limitation on sloping and benching.
BC § 3304.4.2
Where sloping or benching is utilized to support an excavation, the slope or bench step shall be appropriate for conditions at the site, including but not limited to soil type, environmental conditions, and surcharge loads. In no case shall the maximum slope or bench step for an excavation that is 5 feet (1524 mm) or greater in depth exceed the values specified in Table 3304.4.2. For layered soil conditions, the most restrictive value among the soil types present at the excavation location shall be utilized unless otherwise specified by the registered design professional and indicated on the construction documents required by Section 3304.4.1. Exception: The limitations of Table 3304.4.2 shall not apply to excavations made in Class 1a, 1b, or 1c rock, as classified by Chapter 18, provided the geotechnical report required by Section 1803.6 substantiates the safety of the proposed slope, cut, or bench step, and further provided that the resulting slope, cut, or bench step, as well as any supplemental support of the rock face, is indicated on the construction documents required by Section 3304.4.1. Table 3304.4.2Maximum Allowable Slopes and Steps Soil TypeMaximum Allowable Slopes(Horizontal: Vertical)Maximum AllowableBench StepType A soil1:1 (45º)5 feet (1524 mm)Type B soil1:1 (45º)4 feet (1219 mm)Type C soil1 1/2:1 (34º)Not allowed
