CPESC Site Assessment & Planning 3 — Questions and Answers
Question 1: Which element of a Stormwater Pollution Prevention Plan (SWPPP) specifically addresses the sequence of BMPs to be installed before, during, and after construction?
- Site description and location map
- BMP implementation schedule and sequence (Correct answer)
- Inspection and maintenance log
- Post-construction stormwater management section
Correct answer: BMP implementation schedule and sequence
The BMP implementation schedule details the timing and sequencing of erosion and sediment controls relative to construction activities.
Question 2: A slope aspect analysis during site assessment is most valuable for predicting:
- The direction of prevailing winds for dust control planning
- Soil moisture and vegetation recovery rates after disturbance (Correct answer)
- The depth to seasonal high water table
- Runoff volume during peak storm events
Correct answer: Soil moisture and vegetation recovery rates after disturbance
Slope aspect (north vs. south facing) significantly affects solar radiation, moisture retention, and the ability of vegetation to establish after disturbance.
Question 3: When delineating drainage areas for a construction site, which tool provides the most accurate watershed boundary information?
- Aerial photography from Google Earth
- USGS topographic quadrangle maps with 10-foot contour intervals
- LiDAR-derived digital elevation models (DEMs) (Correct answer)
- Field observation during a dry period
Correct answer: LiDAR-derived digital elevation models (DEMs)
LiDAR-derived DEMs provide high-resolution elevation data that enables accurate automated watershed delineation, especially in flat or complex terrain.
Question 4: The 'design storm' used for sizing sediment basins on most construction sites is typically:
- The 2-year, 24-hour storm event
- The 10-year, 24-hour storm event (Correct answer)
- The 25-year, 24-hour storm event
- The 100-year, 24-hour storm event
Correct answer: The 10-year, 24-hour storm event
Most state regulations and guidance documents require sediment basins to be sized for the 10-year, 24-hour storm event to provide adequate protection.
Question 5: Which type of soil map unit description is most useful when planning erosion control BMPs for a construction site?
- Soil series name and taxonomic classification
- Erodibility (K value), slope range, and drainage class (Correct answer)
- Cation exchange capacity and base saturation
- Soil map unit acreage and percentage inclusions
Correct answer: Erodibility (K value), slope range, and drainage class
K values (erodibility), slope range, and drainage class directly inform BMP selection, placement, and sizing decisions for erosion control.
Question 6: During site assessment, evidence of active rills on an existing slope indicates:
- The soil has high infiltration capacity
- Concentrated surface runoff is already occurring and erosion is active (Correct answer)
- The slope is stable and self-draining
- Subsurface drainage is functioning properly
Correct answer: Concentrated surface runoff is already occurring and erosion is active
Rills are small channels formed by concentrated overland flow, indicating that active sheet flow has already concentrated into erosive channels on the slope.
Question 7: A CPESC practitioner identifies hydric soils during site assessment. This finding primarily requires:
- Immediate soil amendment with lime before construction
- Wetland delineation and coordination with regulatory agencies (Correct answer)
- Installation of deeper silt fence posts due to soft soils
- Selection of drought-tolerant seed mixes for revegetation
Correct answer: Wetland delineation and coordination with regulatory agencies
Hydric soils are indicators of potential wetlands, which require delineation and may trigger permits from the Army Corps of Engineers and state agencies.
CPESC Site Assessment & Planning 3
Which element of a Stormwater Pollution Prevention Plan (SWPPP) specifically addresses the sequence of BMPs to be installed before, during, and after construction?