A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
Correct Answer
C) 1:1 (horizontal to vertical)
For Type B soil, OSHA requires a maximum slope of 1:1 (45 degrees) when no protective system is used. This means one foot horizontal for every one foot vertical.
Why This Is the Correct Answer
OSHA 29 CFR 1926.652 specifies that Type B soil requires a maximum slope ratio of 1:1 (horizontal to vertical) when excavated without protective systems. This translates to a 45-degree angle from horizontal. Type B soil has moderate cohesive strength and can stand vertically for short periods, but requires this specific slope for safety in deeper excavations like this 8-foot trench.
Why the Other Options Are Wrong
Option A: 1/2:1 (horizontal to vertical)
A 1/2:1 slope ratio (0.5 horizontal to 1 vertical) would create a steeper angle than allowed, making the trench walls too vertical and unsafe for Type B soil conditions.
Option B: 3/4:1 (horizontal to vertical)
A 3/4:1 slope ratio (0.75 horizontal to 1 vertical) is still too steep for Type B soil and does not meet OSHA's minimum safety requirements for this soil classification.
Option D: 1.5:1 (horizontal to vertical)
While a 1.5:1 slope ratio would be safer than required, it's not the maximum allowable slope - OSHA permits up to 1:1, so this answer doesn't reflect the regulatory standard being tested.
Memory Technique
Type B = 1:1 - Think 'B for Balanced' since 1:1 is a perfectly balanced ratio, and Type B soil is the middle classification between Type A and Type C.
Reference Hint
OSHA 29 CFR 1926.652 - Requirements for protective systems, Table B-1 for maximum allowable slopes
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