PIC EPA Stormwater & Erosion Control 3 — Questions and Answers
Question 1: A paving inspector notices that silt fences on a project have been installed parallel to the slope contours but are sagging and not trenched in. What corrective action is required?
- Replace silt fences with sediment basins immediately
- Re-install the silt fences with the fabric trenched and backfilled into the ground (Correct answer)
- Add additional posts every 10 feet to support the sag
- Remove the silt fences since they are installed incorrectly and are ineffective
Correct answer: Re-install the silt fences with the fabric trenched and backfilled into the ground
Silt fence fabric must be trenched into the ground at least 6 inches and backfilled to prevent stormwater from undermining the fence and bypassing the BMP.
Question 2: Which EPA regulation established the framework for the NPDES Construction General Permit that governs stormwater discharges from construction sites?
- Clean Air Act Section 112
- Clean Water Act Section 402 (Correct answer)
- Resource Conservation and Recovery Act Section 3008
- Safe Drinking Water Act Section 1421
Correct answer: Clean Water Act Section 402
Section 402 of the Clean Water Act established the NPDES program, under which the CGP is issued to regulate stormwater discharges from construction activities.
Question 3: What is the maximum slope gradient at which standard silt fence is considered an effective sediment control BMP without additional reinforcement?
- 5%
- 10% (Correct answer)
- 15%
- 20%
Correct answer: 10%
Standard silt fence is generally effective on slopes up to 1:10 (10%) gradient; steeper slopes require reinforced fence or alternative BMPs.
Question 4: During paving operations, a contractor uses a street sweeper daily on an adjacent road. Under stormwater regulations, this practice primarily addresses which type of pollution?
- Concrete washout contamination
- Sediment tracking from vehicles leaving the site (Correct answer)
- Fuel spills from paving equipment
- Dust from aggregate stockpiles
Correct answer: Sediment tracking from vehicles leaving the site
Daily street sweeping removes tracked sediment from public roadways, preventing it from washing into storm drains during rain events.
Question 5: When a construction project's SWPPP is amended to reflect site changes, who is responsible for signing and certifying the updated plan?
- The local municipality's stormwater inspector
- The project engineer of record only
- A responsible party with legal authority, such as the operator or authorized representative (Correct answer)
- The EPA regional administrator
Correct answer: A responsible party with legal authority, such as the operator or authorized representative
SWPPP amendments must be signed and certified by the operator or an authorized representative who has legal responsibility for the project.
Question 6: A sediment basin is required on a construction site when the drainage area to a common point exceeds how many acres of disturbed soil?
- 1 acre
- 5 acres
- 10 acres (Correct answer)
- 25 acres
Correct answer: 10 acres
EPA's CGP and many state standards require a sediment basin when the contributing disturbed drainage area exceeds 10 acres.
Question 7: Which condition allows a construction operator to submit a Notice of Termination (NOT) for a CGP permit?
- When paving of the final lift is complete
- When final stabilization has been achieved and all temporary BMPs removed (Correct answer)
- When the project is 80% complete by cost
- When the rainy season has ended
Correct answer: When final stabilization has been achieved and all temporary BMPs removed
An NOT can be submitted only after final stabilization is achieved — meaning all disturbed areas have been stabilized with permanent vegetation or equivalent cover — and temporary BMPs are removed.
PIC EPA Stormwater & Erosion Control 3
A paving inspector notices that silt fences on a project have been installed parallel to the slope contours but are sagging and not trenched in.
What corrective action is required?