CPII Drainage & Stormwater Management 3

Question 1

What is the primary function of a sediment trap or sediment basin on a construction site?

Accepted Answer

To capture sediment-laden stormwater and allow sediment to settle before discharge

Answer

To store clean water for dust suppression activities on the site

Answer

To collect chemical waste generated during construction operations

Answer

To redirect dewatering discharge away from public roadways

Question 2

During a drainage system inspection, an inspector identifies a pipe with a large void in the surrounding soil visible through a joint opening. What is the MOST immediate concern?

Accepted Answer

Subsurface erosion (piping) that could cause pavement or ground surface failure

Answer

Reduced hydraulic efficiency due to joint misalignment

Answer

Increased maintenance costs from sediment entering the pipe

Answer

Loss of pipe bedding material from freeze-thaw cycles

Question 3

Which type of inlet is generally preferred in areas with high pedestrian or bicycle traffic due to safety considerations?

Accepted Answer

Curb-opening inlets or combination inlets with pedestrian-safe grate designs

Answer

Open-grate inlets with parallel bars oriented with traffic flow

Answer

Drop inlets with large rectangular grate openings

Answer

Slotted drain inlets with wide transverse openings

Question 4

When reviewing drainage as-built plans during an inspection, what does a dashed line typically represent on a storm drain plan sheet?

Accepted Answer

An existing underground pipe or structure not visible from the surface

Answer

A proposed but not yet constructed drainage structure

Answer

A temporary erosion control measure installed during construction

Answer

A property boundary line adjacent to the drainage easement

Question 5

What is the recommended minimum pipe cover depth for storm drain pipes under roadways to prevent crushing from traffic loads?

Accepted Answer

2 to 3 feet (depending on pipe material and loading)

Answer

6 inches

Answer

12 inches

Answer

5 feet

Question 6

An inspector observes that a headwall at a culvert outlet has been undermined and tilted. What is the MOST probable cause?

Accepted Answer

Scour at the outlet caused by uncontrolled high-velocity discharge

Answer

Excessive upstream sediment deposition blocking the culvert inlet

Answer

Frost heave from seasonal freezing and thawing of subgrade soils

Answer

Settlement of the culvert pipe barrel under traffic loading

Question 7

Which of the following is a key indicator that a stormwater retention pond is NOT functioning as designed for water quality treatment?

Accepted Answer

Hydraulic short-circuiting where inflow exits rapidly without mixing throughout the pond

Answer

Presence of aquatic vegetation along the pond shoreline

Answer

Seasonal fluctuation in the permanent pool water level

Answer

Accumulation of sediment in the forebay near the inlet