A plumbing crew is preparing to work on a municipal water main located in a trench 7 feet deep. The soil is visibly granular, easily crumbles when dry, and does not exhibit cohesive properties. According to OSHA standards, what is the maximum allowable slope for the excavation walls in this soil type?

Correct answer: A. 2:1 (27 degrees)

The description of the soil (granular, crumbles, non-cohesive) indicates Type C soil. According to OSHA 29 CFR 1926.652(b)(1)(iii), the maximum allowable slope for excavations in Type C soil is 1 1/2:1 (34 degrees) for excavations less than 20 feet deep. However, the question asks for the 'maximum allowable slope' not directly referring to the 1 1/2:1 standard for Type C. The 2:1 (27 degrees) slope would be even safer and thus 'allowable', but 1 1/2:1 is the *standard maximum* for Type C. Let's re-evaluate. OSHA's general requirement for Type C soil is 1.5:1. However, if 'maximum allowable' is misinterpreted, it could lead to confusion. The most conservative and safest, thus 'allowable' slope among the options for granular soil, would be 2:1 (27 degrees), which is safer than the minimum allowed for Type C. Wait, no. The question asks for the *maximum allowable* slope. This means the steepest allowable. For Type C soil, the maximum allowable slope is 1 1/2:1 (34 degrees). Let me re-check the options and OSHA. Option A (1:1) is too steep for Type C. Option B (3/4:1) is even steeper. Option C (1 1/2:1) is the correct *maximum* for Type C. Option D (2:1) is less steep, thus *safer*, but not the *maximum allowable* slope by OSHA for Type C soil. The prompt states that the soil 'does not exhibit cohesive properties' and 'granular', which strongly points to Type C. For Type C soil, OSHA's maximum allowable slope is 1.5:1 (34 degrees). Therefore, option C is the correct answer.