CPESC Construction Site Controls 4 — Questions and Answers
Question 1: A fiber roll (straw wattle) installed on a slope begins to shift and roll downhill after a storm. What was the most likely installation error?
- The fiber roll was too small in diameter
- The fiber roll was not staked securely or installed on the contour (Correct answer)
- The fiber roll material was inappropriate for the slope gradient
- The fiber roll was installed too close to the toe of slope
Correct answer: The fiber roll was not staked securely or installed on the contour
Fiber rolls must be staked firmly into the ground and installed precisely on the contour to prevent displacement by runoff or gravity.
Question 2: Which of the following best describes the 'common plan of development' concept under NPDES stormwater regulations?
- A single building permit covering multiple structures
- A plan where multiple separate construction projects together disturb one or more acres, triggering permit coverage (Correct answer)
- A shared stormwater management plan between adjacent property owners
- A phased grading plan approved by the local municipality
Correct answer: A plan where multiple separate construction projects together disturb one or more acres, triggering permit coverage
A common plan of development means that even small individual lots, if part of a larger planned development, collectively trigger NPDES permit requirements when total disturbance exceeds one acre.
Question 3: What is the correct method for installing silt fence on a hillside to maximize its effectiveness?
- Install parallel to the slope in a straight line downhill
- Install in a 'J-hook' or 'C-shape' configuration along the contour with turned-up ends (Correct answer)
- Install at the downhill property line only
- Install perpendicular to the contour in straight runs
Correct answer: Install in a 'J-hook' or 'C-shape' configuration along the contour with turned-up ends
A J-hook or C-shaped silt fence installation on the contour with upturned ends prevents runoff from flowing around the ends and channels water to a central low point.
Question 4: Which condition would cause a sediment basin to fail to meet its design water quality objectives?
- The basin has a skimmer outlet instead of a riser pipe
- The basin's surface area is undersized, resulting in excessive overflow velocity and inadequate settling time (Correct answer)
- The basin is vegetated along its interior slopes
- The basin receives runoff from a drainage area smaller than the design area
Correct answer: The basin's surface area is undersized, resulting in excessive overflow velocity and inadequate settling time
An undersized basin surface area means water moves through too quickly, preventing clay and fine silt particles from settling before discharge.
Question 5: A construction site manager wants to use concrete washout water for dust control on haul roads. Why is this practice prohibited?
- Concrete washout water is too expensive to transport
- Concrete washout water has a very high pH and can damage aquatic life if it reaches waterways (Correct answer)
- It will damage the surface of compacted haul roads
- Concrete washout water contains too much gravel to be sprayed
Correct answer: Concrete washout water has a very high pH and can damage aquatic life if it reaches waterways
Concrete washout water has a pH often above 12, which is highly caustic and toxic to aquatic organisms if discharged to stormwater systems.
Question 6: Which factor most directly determines the minimum size of a sediment trap?
- The height of the embankment
- The drainage area contributing runoff to the trap (Correct answer)
- The type of soil on the construction site
- The distance to the nearest waterway
Correct answer: The drainage area contributing runoff to the trap
Sediment trap size is primarily determined by the contributing drainage area, as larger areas generate greater runoff volumes requiring more retention capacity.
Question 7: What does 'dewatering' mean in the context of construction site stormwater management?
- The process of removing vegetation to prepare a site for grading
- Pumping or draining accumulated water from excavations or low points, which must be treated before discharge (Correct answer)
- Reducing irrigation on revegetated slopes during dry periods
- Installing subdrainage systems to lower the water table permanently
Correct answer: Pumping or draining accumulated water from excavations or low points, which must be treated before discharge
Construction dewatering involves removing ponded or accumulated water from excavations, and the discharged water must be treated to remove sediment before leaving the site.
CPESC Construction Site Controls 4
A fiber roll (straw wattle) installed on a slope begins to shift and roll downhill after a storm.
What was the most likely installation error?