BLArch Bachelor of Landscape Architecture Grading and Drainage 2 — Questions and Answers
Question 1: What is the primary purpose of a 'detention basin' in stormwater management?
- Permanently store water for irrigation
- Temporarily hold stormwater and release it slowly to reduce peak flow (Correct answer)
- Filter pollutants through vegetation
- Provide habitat for aquatic species year-round
Correct answer: Temporarily hold stormwater and release it slowly to reduce peak flow
A detention basin temporarily stores stormwater during a rain event and releases it slowly, reducing downstream peak flow rates.
Question 2: In grading plans, contour lines that are closer together indicate:
- Flatter terrain
- Steeper slopes (Correct answer)
- Wetter soils
- Higher elevations only
Correct answer: Steeper slopes
Closely spaced contour lines represent steeper slopes because the same elevation change occurs over a shorter horizontal distance.
Question 3: What is the ADA-required maximum cross slope for accessible pedestrian paths?
- 1%
- 2% (Correct answer)
- 3%
- 5%
Correct answer: 2%
ADA standards require that accessible paths have a maximum cross slope of 2% (1:50) to prevent wheelchair instability.
Question 4: Which of the following stormwater management strategies reduces impervious surface area?
- Concrete curb and gutter
- Pervious pavement (Correct answer)
- Sloped asphalt parking lots
- Storm sewer pipe expansion
Correct answer: Pervious pavement
Pervious pavement allows water to infiltrate through the surface, reducing runoff volume and mimicking natural hydrology.
Question 5: What is the term for the low point in a grading plan where water collects and must be drained?
- Crown
- Ridge
- Sump or low point (Correct answer)
- High point
Correct answer: Sump or low point
A sump or low point is the lowest elevation on a graded surface; it must have a drain or outlet to prevent ponding.
Question 6: Which instrument is commonly used in the field to verify grading elevations during construction?
- Transit level or auto level (Correct answer)
- GPS rover only
- Surveyor's chain
- Clinometer
Correct answer: Transit level or auto level
A transit level or automatic level is used to verify grading elevations during construction by sighting horizontal datum across the site.
BLArch Bachelor of Landscape Architecture Grading and Drainage 2
What is the primary purpose of a 'detention basin' in stormwater management?