North Carolina (NC) (H) Grading & Excavating Practice Exam Questions With Correct Answers Verified Instant Download Pdf

1. A contractor is excavating a trench that is 12 feet deep. According to OSHA standards incorporated by NC OSH, what is the single most critical factor that determines the required protective system? A) The width of the trench at the bottom B) The type of excavation equipment being used C) The results of a competent person’s soil classification D) The distance to the nearest property line Correct Answer: C Deep Explanation: OSHA 1926 Subpart P mandates that before any worker enters an excavation 5 feet deep or more, a competent person must classify the soil type (e.g., Type A, B, or C). This classification directly dictates the allowable slope angles, shoring spacing, or shielding requirements. Without correct soil classification, any protective system is invalid. 2. In a trench that is 10 feet deep with Type B soil, what is the maximum allowable slope angle for an unsupported excavation according to federal OSHA standards enforced in NC? A) 1:1 (45 degrees) B) 3/4:1 (53 degrees) C) 1.5:1 (34 degrees)D) 2:1 (63 degrees) Correct Answer: A Deep Explanation: For Type B soil, OSHA 1926.652(b) requires a maximum slope of 1:1 (horizontal to vertical). This means for every foot of depth, the trench wall must be cut back one foot. Type A allows 3/4:1, Type C requires 1.5:1. Slope is measured from the horizontal. 3. You discover water seeping into a 9-foot deep excavation in sandy clay loam. As the competent person, you must immediately: A) Install a pump and continue work if water is removed within 2 hours B) Reclassify the soil as Type C and implement a protective system for Type C C) Ignore the water if it’s less than 2 inches deep D) Install a ladder and proceed with caution Correct Answer: B Deep Explanation: Water seepage automatically reduces soil stability. NC OSH follows OSHA 1926 Subpart P App A, stating that water conditions require reclassification to Type C soil (the least stable). Type C requires a 1.5:1 slope or engineered shoring. Pumping alone does not remove the classification requirement. 4. A 14-foot deep trench is excavated in stable rock. What protective system is required under NC OSH rules? A) Benching at 3/4:1 slope B) Shoring every 4 feet vertically C) No protective system required for stable rock D) Trench box with 12-inch clearance Correct Answer: C Deep Explanation: OSHA 1926.652(b)(2) exempts excavations made entirely in stable rock from sloping or shoring requirements, provided the competent person verifies the rock is stable and will not fracture. However, a ladder must still be provided for egress if depth exceeds 4 feet.5. The NC Department of Transportation (NCDOT) grading permit requires a sediment and erosion control plan. The primary legal document governing this in North Carolina is the: A) Clean Water Act Section 404 permit B) NC Sedimentation Pollution Control Act (SPCA) C) NC Mining Act of 1971 D) NC Stormwater Management Ordinance Correct Answer: B Deep Explanation: The NC Sedimentation Pollution Control Act (G.S. 113A-50 et seq.) is the state law that requires erosion and sediment control plans for land-disturbing activities of 1 acre or more. It is enforced by local delegated programs or NCDEQ. The other options are federal or different state laws. 6. On a grading site, you install a silt fence. The maximum allowable slope length above a silt fence in North Carolina for a moderate erosion potential soil is: A) 50 feet B) 100 feet C) 150 feet D) 200 feet Correct Answer: B Deep Explanation: According to the NC Erosion and Sediment Control Planning and Design Manual, the maximum slope length above a silt fence is generally 100 feet to prevent overtopping and failure. Longer slopes require additional terraces or alternative controls due to increased runoff velocity. 7. A competent person has identified Type A soil in a trench. However, the trench is located within 1.5 feet of a roadway that vibrates from heavy truck traffic. How does this affect the soil classification? A) No change; Type A remains if vibration is minimal B) Reclassify as Type B due to vibration C) Reclassify as Type C automaticallyD) Type A is allowed but must use a trench shield Correct Answer: B Deep Explanation: OSHA 1926 Subpart P App A requires reclassification to Type B when Type A soil is subject to vibration from traffic, pile driving, or similar sources. Vibration reduces soil cohesion. Reclassification triggers less steep slopes or different shoring. 8. What is the maximum allowable spacing for ladders in a trench that is 100 feet long, 8 feet deep, according to NC OSH? A) One ladder within 25 feet of every worker B) Ladders spaced no more than 50 feet apart laterally C) Ladders at each end only D) No ladders required for trenches less than 10 feet deep Correct Answer: A Deep Explanation: OSHA 1926.652(c) requires that ladders, stairways, or ramps be located so that no worker travels more than 25 feet laterally to reach an exit point from the excavation. For a 100-foot trench, at least 2 ladders are needed (spaced ~33-50 ft apart) to satisfy the 25-ft rule. 9. You are calculating the volume of earth to be excavated for a building pad. The site is 200 ft long, 150 ft wide, and cut depth is 3 ft. What is the bank cubic yards (BCY) volume? A) 90,000 BCY B) 3,333 BCY C) 10,000 BCY D) 25,000 BCY Correct Answer: B Deep Explanation: Volume in cubic feet = length × width × depth = 200 × 150 × 3 = 90,000 cu ft. Convert to cubic yards: 90,000 / 27 = 3,333.33 BCY. Bank cubic yards refer to earth in its natural, undisturbed state. This is the baseline for earthwork calculations.10. After excavation, the same 3,333 BCY of clay is placed as fill. If the swell factor for clay is 40%, how many loose cubic yards (LCY) must be hauled? A) 3,333 LCY B) 4,666 LCY C) 2,000 LCY D) 5,500 LCY Correct Answer: B Deep Explanation: Swell factor = 1 + swell percentage. 40% swell = 1.40. Loose volume = bank volume × swell factor = 3,333 × 1.40 = 4,666.2 LCY. This accounts for the expansion of soil particles when disturbed and loaded into trucks. 11. A trench box is used for an 11-foot deep trench. According to NC OSH, which statement about using the trench box is correct? A) The box must extend at least 18 inches above the vertical wall B) Workers may be outside the box if the trench is less than 12 feet deep C) The box must protect workers from cave-ins within the shielded area only D) The box can be dragged horizontally while workers are inside Correct Answer: C Deep Explanation: A trench box (shield) is designed to withstand lateral earth pressure; it protects workers only when they are inside the protected zone. Workers must not be outside the shield at depths greater than 4 feet. The box does not need to extend above the trench wall (that applies to sheeting). 12. In North Carolina, who has the authority to issue a stop-work order for a grading operation that is causing sediment to leave the site? A) Only NCDOT B) Local building inspector C) NC Division of Energy, Mineral, and Land Resources (DEMLR) or delegated local program D) County sheriff Correct Answer: CDeep Explanation: The NC DEMLR (formerly DENR) and its delegated local erosion control programs have enforcement authority under the Sedimentation Pollution Control Act. They can issue notices of violation, stop-work orders, and fines up to $5,000 per day. 13. A backhoe is excavating next to an existing 6-foot deep foundation. The competent person determines the foundation soil is Type A but the excavation will be 8 feet deep. What is the minimum distance the backhoe must stay from the foundation to avoid surcharge loading? A) 4 feet B) 6 feet C) 8 feet D) 12 feet Correct Answer: C Deep Explanation: OSHA 1926.651(k) requires that excavated soil or equipment be kept at least 2 feet from the edge of an excavation. For foundations, the minimum distance from the edge to the top of the foundation’s pressure bulb is often equal to the excavation depth. More precisely, surcharge loads must not exceed the soil’s bearing capacity.