NETTCP Drainage & Stormwater Management

Question 1

Which type of culvert pipe material is most resistant to corrosion in acidic soil environments common in New England?

Accepted Answer

High-density polyethylene (HDPE) pipe

Answer

Corrugated metal pipe (CMP)

Answer

Reinforced concrete pipe (RCP)

Answer

Cast iron pipe

Question 2

What is the primary purpose of a catch basin in a highway drainage system?

Accepted Answer

To collect surface runoff and trap sediment before it enters the storm sewer

Answer

To retain stormwater for groundwater recharge

Answer

To measure peak flow rates during storm events

Answer

To distribute flow evenly across multiple outlet pipes

Question 3

Manning's equation is used in drainage design primarily to calculate:

Accepted Answer

Flow velocity and discharge in open channels and pipes

Answer

Soil permeability coefficients

Answer

Groundwater table elevation

Answer

Sediment load in stormwater runoff

Question 4

During a culvert inspection, you observe headwater depth approaching the crown of the inlet. This condition indicates:

Accepted Answer

The culvert barrel is undersized or partially blocked and flow is restricted

Answer

The culvert is operating under inlet control at full capacity

Answer

Normal operating conditions for a properly designed culvert

Answer

The outlet is submerged causing backwater effects

Question 5

What minimum pipe bedding material gradation is typically required beneath drainage pipe to provide uniform support and prevent settlement?

Accepted Answer

Clean crushed stone or gravel free of fines, typically 3/4" to 1-1/2"

Answer

Bank-run gravel with up to 50% fines

Answer

Native soil compacted to 95% density

Answer

Cement-stabilized sand

Question 6

The rational method formula Q = CiA is used to estimate peak stormwater runoff. What does the variable 'C' represent?

Accepted Answer

Runoff coefficient reflecting land use and soil type

Answer

Channel conveyance factor

Answer

Time of concentration in minutes

Answer

Catchment area in acres

Question 7

Under federal NPDES Phase II regulations, which of the following highway construction activities requires a stormwater pollution prevention plan (SWPPP)?

Accepted Answer

Any project disturbing more than 1 acre of land

Answer

Only projects within 200 feet of a waterbody

Answer

Projects with an estimated cost exceeding $500,000

Answer

Only projects on federal-aid highways