CPESC BMP Selection 3 — Questions and Answers
Question 1: Which BMP combination is most effective for a site with clay soils that generate significant turbid runoff?
- Silt fence alone
- Sediment basin with polyacrylamide (PAM) treatment (Correct answer)
- Gravel filter berm
- Fiber rolls and seeding only
Correct answer: Sediment basin with polyacrylamide (PAM) treatment
Clay particles are very fine and slow to settle, so combining a sediment basin with PAM flocculation dramatically improves settling efficiency.
Question 2: A BMP that redirects runoff away from a disturbed slope and discharges it to a stabilized outlet is best described as a:
- Perimeter control
- Diversion BMP (Correct answer)
- Outlet protection structure
- Velocity dissipater
Correct answer: Diversion BMP
Diversion BMPs such as diversion dikes or swales redirect runoff away from disturbed areas and route it to a stable outlet.
Question 3: When selecting inlet protection for a curb-opening storm drain during active construction, which factor most influences BMP type?
- The pipe diameter downstream
- The expected flow rate and ponding tolerance (Correct answer)
- The color of the geotextile fabric
- The depth of the catch basin
Correct answer: The expected flow rate and ponding tolerance
Expected flow rate and ponding tolerance determine whether a gravel-filled bag, filter insert, or other inlet protection is appropriate without causing flooding.
Question 4: Which stabilization BMP is most appropriate for a channel that carries intermittent high-velocity flow and cannot support vegetation immediately?
- Temporary seeding with mulch
- Riprap lining (Correct answer)
- Compost blanket
- Straw wattles
Correct answer: Riprap lining
Riprap provides immediate, durable protection against high-velocity flows in channels where vegetation cannot establish quickly enough.
Question 5: In a semi-arid climate with infrequent but intense rainfall, which BMP characteristic is most critical for effectiveness?
- Low installation cost
- High flow capacity to handle peak runoff (Correct answer)
- Biodegradable materials
- Ease of removal after construction
Correct answer: High flow capacity to handle peak runoff
In semi-arid areas, intense storms generate high peak flows, so BMPs must have sufficient capacity to handle rapid runoff without failure.
Question 6: Which BMP is primarily used to prevent vehicle tracking of sediment onto public roads from a construction site?
- Stabilized construction entrance (Correct answer)
- Perimeter silt fence
- Temporary seeding
- Sediment trap
Correct answer: Stabilized construction entrance
A stabilized construction entrance uses aggregate or other materials to dislodge mud from vehicle tires before they exit the site onto public roads.
Question 7: What is the primary purpose of outlet protection (riprap apron or energy dissipater) at a pipe outlet?
- Filtering sediment from pipe discharge
- Preventing scour from high-velocity discharge (Correct answer)
- Measuring flow volume
- Reducing pipe clogging
Correct answer: Preventing scour from high-velocity discharge
Outlet protection dissipates the kinetic energy of water exiting a pipe at high velocity, preventing scour of the receiving channel or slope.
CPESC BMP Selection 3
Which BMP combination is most effective for a site with clay soils that generate significant turbid runoff?