What is the maximum allowable slope for excavations in type B soil that are less than 20 feet deep?

For excavations in type B soil that are less than 20 feet deep, the maximum allowable slope is indeed 1:1. This means that for every foot of vertical depth, there should be at least one foot of horizontal distance from the edge of the excavation. This slope is designed to ensure stability and reduce the risk of collapse, which is particularly important in type B soils, which are cohesive and can support steeper slopes compared to more granular soils.

Type B soils include materials such as silty clay and sandy clay, and the 1:1 slope is considered safe to provide adequate support. Other options present different slope ratios that do not comply with the standards set for type B soils at these depths, indicating a greater degree of risk which could lead to potential cave-ins or safety hazards. Thus, the 1:1 slope is both practical and essential for maintaining excavation safety in this type of soil.