FDOT Drainage and Stormwater Management 2 — Questions and Answers
Question 1: What is the minimum pipe cover required under FDOT traveled roadways for storm drain pipes?
- 12 inches
- 18 inches (Correct answer)
- 24 inches
- 36 inches
Correct answer: 18 inches
FDOT requires a minimum of 18 inches of cover over storm drain pipes under traveled roadways to protect against traffic loads and prevent crushing.
Question 2: According to FDOT standards, what is the minimum slope required for storm drain laterals to maintain self-cleaning velocity?
- 0.10%
- 0.20%
- 0.30% (Correct answer)
- 0.50%
Correct answer: 0.30%
FDOT requires a minimum slope of 0.30% for storm drain laterals to maintain the minimum self-cleaning velocity of approximately 2 fps.
Question 3: What is the function of a mitered end section (MES) on a culvert pipe?
- Control flow velocity at the outlet
- Transition the pipe end to match the slope of the fill embankment (Correct answer)
- Filter sediment before discharge
- Prevent wildlife from entering the pipe
Correct answer: Transition the pipe end to match the slope of the fill embankment
A mitered end section transitions the pipe end at an angle to match the embankment slope, providing a neat appearance and reducing scour.
Question 4: Under FDOT specifications, what bedding material is typically required for reinforced concrete pipe in Type II bedding?
- Native soil compacted to 95% Proctor
- Coarse sand or granular material (Correct answer)
- Flowable fill
- Crushed stone No. 57
Correct answer: Coarse sand or granular material
FDOT Type II bedding requires coarse sand or approved granular material shaped to provide uniform support along the pipe barrel.
Question 5: What FDOT environmental permit is typically required for stormwater management systems discharging to state waters?
- Environmental Resource Permit (ERP) (Correct answer)
- National Pollutant Discharge Elimination System (NPDES) Permit only
- Coastal Construction Control Line (CCCL) Permit
- U.S. Army Corps Section 404 Permit only
Correct answer: Environmental Resource Permit (ERP)
An Environmental Resource Permit (ERP) from the Florida Department of Environmental Protection or water management district is required for stormwater systems discharging to state waters.
Question 6: What is a 'french drain' as used in FDOT highway drainage design?
- A trench drain with a metal grate
- A perforated pipe in a gravel-filled trench for subsurface drainage (Correct answer)
- An outfall structure draining to a French Creek tributary
- A roadside swale with specific geometry
Correct answer: A perforated pipe in a gravel-filled trench for subsurface drainage
A french drain consists of a perforated pipe surrounded by gravel in a trench, designed to intercept and redirect subsurface groundwater.
FDOT Drainage and Stormwater Management 2
What is the minimum pipe cover required under FDOT traveled roadways for storm drain pipes?