A trench is being excavated in Type B soil. If the trench is 12 feet deep, what is the maximum allowable slope ratio for the sides without additional protective systems?
Correct Answer
A) 1:1 (45 degrees)
For Type B soil, OSHA requires a maximum slope of 1:1 (45 degrees) or flatter when excavations exceed 5 feet in depth.
Why This Is the Correct Answer
OSHA 29 CFR 1926 Subpart P classifies Type B soil as moderately cohesive (e.g., angular gravel, silt, previously disturbed soil). For excavations deeper than 5 feet in Type B soil, the maximum allowable slope is 1:1 (horizontal:vertical), which equals 45 degrees. This gives the soil enough angle to remain stable without shoring or shielding.
Why the Other Options Are Wrong
Option B: 0.75:1 (53 degrees)
A 0.75:1 slope (53 degrees) is the standard for Type A soil — the most stable classification (e.g., intact hard clay). Applying a Type A slope to Type B soil creates a steeper wall that exceeds what Type B can safely support, increasing cave-in risk.
Option C: 2:1 (26.5 degrees)
A 2:1 slope (26.5 degrees) is required for Type C soil — the least stable classification (e.g., gravel, sand, submerged soil). Using Type C requirements in Type B soil means unnecessarily wide excavations; if someone confused the association and applied it as a Type B answer, it would be incorrect because the question asks for the maximum allowable slope (steepest permitted), not the most conservative option.
Option D: 1.5:1 (34 degrees)
A 1.5:1 slope (34 degrees) does not correspond to any OSHA soil classification standard for simple slope excavations. It falls between Type A and Type B requirements and is a distractor with no regulatory basis.
Memory Technique
Use the ABC ladder: **A = Aggressive slope (0.75:1)**, **B = Basic slope (1:1)**, **C = Cautious slope (1.5:1)**. The letter grade matches how cautious you need to be — C soil needs the most caution (flattest slope).
More NASCLA Questions
Which AIA document contains the general conditions that govern the rights and responsibilities of all parties in a construction contract?
A construction company has direct labor costs of $85,000, direct materials of $120,000, and overhead costs of $45,000 for a project. What is the total job cost?
What is the primary purpose of job cost accounting in construction?
A construction company has current assets of $350,000 and current liabilities of $280,000. What is the company's working capital?
In CSI MasterFormat, which division covers earthwork and site preparation?
In a mechanical drawing, what does 'CFM' typically measure?
In CSI MasterFormat Division 08, which of the following would typically be included?
On a mechanical plan, what does the symbol 'RTU' typically indicate?
What is the minimum preheat temperature for welding ASTM A992 steel when the ambient temperature is 15°F?
A general contractor's balance sheet shows total assets of $850,000, current liabilities of $320,000, and long-term debt of $180,000. What is the company's equity?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Project Management
60 questions · 70% to pass
Related Study Resources
Previous Question
A contractor must remit state unemployment tax (SUTA) based on the first $15,000 of each employee's annual wages at a rate of 3.2%. For an employee earning $45,000 annually, what is the SUTA tax liability?
Next Question
A cut and fill operation requires moving 2,500 cubic yards of soil. The soil has a swell factor of 25% and a shrinkage factor of 8%. How many cubic yards must be excavated to achieve 2,500 cubic yards of compacted fill?