CLA CLA Grading & Drainage 2 — Questions and Answers
Question 1: Which method is used to calculate the volume of cut and fill earthwork on a grading project?
- Prismoidal formula or average end area (Correct answer)
- Manning's equation
- Rational method
- Darcy's law
Correct answer: Prismoidal formula or average end area
Earthwork volumes are commonly estimated using the average end area method or the more accurate prismoidal formula.
Question 2: A retention pond holds stormwater permanently, while a detention pond:
- Holds water indefinitely with no outlet
- Temporarily stores water and releases it slowly (Correct answer)
- Filters groundwater only
- Prevents all runoff from leaving a site
Correct answer: Temporarily stores water and releases it slowly
A detention pond temporarily detains stormwater and releases it at a controlled rate through an outlet structure.
Question 3: What slope range is typically considered the maximum for mown grass areas accessible to riding mowers?
- 2–5%
- 5–10% (Correct answer)
- 10–15%
- 15–25%
Correct answer: 5–10%
Riding mowers can safely operate on slopes up to about 10%, above which hand mowers or groundcovers are recommended.
Question 4: In grading plans, what does 'FF 101.50' typically indicate?
- Finish floor elevation (Correct answer)
- Flood frequency at 101.50 years
- Fill factor of 101.50 cubic yards
- Foundation footing at 101.50 feet
Correct answer: Finish floor elevation
FF stands for finished floor elevation, which must sit above the surrounding grade to prevent water intrusion.
Question 5: Which bioretention feature is designed to temporarily pond water and allow it to infiltrate through a soil media layer?
- French drain
- Rain garden (Correct answer)
- Dry well
- Riprap channel
Correct answer: Rain garden
Rain gardens are shallow, vegetated depressions filled with engineered media that allow stormwater to infiltrate and be filtered.
Question 6: What is the term for the elevation difference between the inlet and outlet of a culvert expressed as a percentage?
- Hydraulic gradient
- Pipe slope (Correct answer)
- Head loss
- Flow velocity
Correct answer: Pipe slope
Pipe slope is the vertical drop divided by the pipe length × 100, and it governs flow velocity within the culvert.
CLA CLA Grading & Drainage 2
Which method is used to calculate the volume of cut and fill earthwork on a grading project?