CPESC BMP Selection 2 — Questions and Answers
Question 1: Which BMP is most appropriate for capturing sediment-laden runoff from a disturbed area before it enters a natural waterway?
- Sediment basin (Correct answer)
- Rock check dam
- Silt fence
- Inlet protection device
Correct answer: Sediment basin
A sediment basin is designed to capture and retain runoff from large disturbed areas, allowing sediment to settle before discharge to a waterway.
Question 2: When selecting a BMP for a steep slope (>15%) with high-velocity concentrated flow, which option is most suitable?
- Silt fence
- Fiber rolls
- Rock-lined channel or slope drain (Correct answer)
- Compost blanket
Correct answer: Rock-lined channel or slope drain
Rock-lined channels or slope drains convey high-velocity concentrated flow safely down steep slopes without causing erosion.
Question 3: A construction site has sandy soils with a permeability rate exceeding 1 inch per hour. Which sediment control BMP would be LEAST effective here?
- Sediment basin with perforated riser
- Silt fence without filter fabric backing (Correct answer)
- Compost sock
- Inlet protection with gravel
Correct answer: Silt fence without filter fabric backing
Silt fence relies on filtration through geotextile fabric, but in highly permeable sandy soils the water bypasses the fence through the ground rather than through the fabric.
Question 4: Which factor is PRIMARY when selecting between a temporary sediment trap and a sediment basin?
- Soil type of the disturbed area
- Drainage area size (Correct answer)
- Proximity to a stream
- Construction timeline
Correct answer: Drainage area size
Drainage area size is the primary determinant; sediment traps are typically used for areas up to 5 acres while sediment basins are required for larger drainage areas.
Question 5: On a linear construction project crossing multiple watersheds, what is the best approach for BMP placement?
- Install one large sediment basin at the lowest point
- Place BMPs at each watershed outlet to prevent cross-watershed discharge (Correct answer)
- Use only temporary seeding throughout
- Install silt fence along the entire project perimeter
Correct answer: Place BMPs at each watershed outlet to prevent cross-watershed discharge
BMPs should be placed at each individual watershed outlet to contain sediment within its source watershed and prevent cross-contamination.
Question 6: Which BMP is specifically designed to slow runoff velocity and promote infiltration on relatively flat slopes (1–5%)?
- Rock check dam
- Diversion dike
- Level spreader (Correct answer)
- Flocculent log
Correct answer: Level spreader
A level spreader converts concentrated flow to sheet flow, reducing velocity and promoting infiltration on low-gradient slopes.
Question 7: When must a Pollution Prevention Plan (PPP) specifically address BMP maintenance schedules?
- Only after a rainfall event exceeds 0.5 inches
- At the time of plan development and updated after each inspection (Correct answer)
- Only when sediment escapes the site boundary
- Quarterly regardless of site conditions
Correct answer: At the time of plan development and updated after each inspection
BMP maintenance schedules must be established in the PPP during plan development and revised following site inspections to reflect current conditions.
CPESC BMP Selection 2
Which BMP is most appropriate for capturing sediment-laden runoff from a disturbed area before it enters a natural waterway?