CTQP Earthwork Construction Inspection 2 — Questions and Answers
Question 1: What piece of equipment is commonly used to compact cohesive soils in earthwork operations?
- Smooth drum vibratory roller
- Sheepsfoot or padfoot roller (Correct answer)
- Pneumatic tire roller
- Plate compactor
Correct answer: Sheepsfoot or padfoot roller
Sheepsfoot and padfoot rollers are most effective for compacting cohesive (clay) soils because their feet penetrate and knead the soil.
Question 2: What is the purpose of a subgrade proof roll in earthwork inspection?
- To apply waterproofing to the subgrade surface
- To identify soft or unstable areas in the prepared subgrade (Correct answer)
- To measure the thickness of the subgrade layer
- To compact the top 6 inches of subgrade
Correct answer: To identify soft or unstable areas in the prepared subgrade
A proof roll uses a heavily loaded tandem-axle dump truck driven across the subgrade to identify soft, pumping, or unstable areas that need remediation.
Question 3: What is 'muck excavation' as defined under FDOT pay items?
- Excavation of any material below the water table
- Excavation and removal of organic, unsuitable material (Correct answer)
- Excavation performed with specialized underwater equipment
- Excavation of rock material in wet conditions
Correct answer: Excavation and removal of organic, unsuitable material
Muck excavation is the removal of organic or otherwise unsuitable material from below the ground surface, typically replaced with suitable fill.
Question 4: When inspecting a fill slope, what ratio does '3:1' indicate?
- 3 feet vertical for every 1 foot horizontal
- 1 foot vertical for every 3 feet horizontal (Correct answer)
- 3% grade over 1 mile
- 3 tons of compaction force per 1 square foot
Correct answer: 1 foot vertical for every 3 feet horizontal
A 3:1 slope means 3 feet horizontal for every 1 foot vertical, and is a common slope for embankment side slopes in FDOT projects.
Question 5: Which soil classification system is most commonly referenced in FDOT earthwork specifications?
- USCS (Unified Soil Classification System)
- AASHTO Soil Classification System (Correct answer)
- USDA Textural Classification
- ASTM D 2487
Correct answer: AASHTO Soil Classification System
FDOT references the AASHTO soil classification system, which groups soils A-1 through A-7 based on gradation and Atterberg limits.
Question 6: What document controls the acceptable limits for earthwork on an FDOT project?
- The Standard Specifications for Road and Bridge Construction (Correct answer)
- The geotechnical investigation report only
- The contractor's quality control plan
- The environmental permit
Correct answer: The Standard Specifications for Road and Bridge Construction
FDOT's Standard Specifications for Road and Bridge Construction (and applicable special provisions) govern all earthwork requirements including material acceptance and compaction.